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NGNP-20-RPT-003 January 2007 Revision 0 NGNP and Hydrogen Production Preconceptual Design Report SPECIAL STUDY 20.3: HIGH TEMPERATURE PROCESS HEAT TRANSFER AND TRANSPORT Revision 0 APPROVALS Function Printed Name and Signature Date Author Scott R. Penfield, Jr., PE Technology Insights 26 Jan 2007 Reviewer Fred A. Silady TechnologInsights 26 Jan 2007 Approval L. D. Mears Technology Insights 26 Jan 2007 Westinghouse Electric Company LLC Nuclear Power Plants Post Office Box 355 Pittsburgh, PA 15230-0355 2007 Westinghouse Electric Company LLC All Rights Reserved

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Page 1: NGNP and Hydrogen Production Preconceptual Design Report Documents... · NGNP and Hydrogen Production Preconceptual Design Report NGNP-20-RPT-003 Special Study 20.3 – High Temperature

NGNP-20-RPT-003 January 2007

Revision 0

NGNP and Hydrogen Production

Preconceptual Design Report

SPECIAL STUDY 20.3: HIGH TEMPERATUREPROCESS HEAT TRANSFER AND TRANSPORT

Revision 0

APPROVALS

Function Printed Name and Signature Date

Author Scott R. Penfield, Jr., PE

Technology Insights

26 Jan 2007

Reviewer Fred A. SiladyTechnologInsights

26 Jan 2007

Approval L. D. Mears

Technology Insights

26 Jan 2007

Westinghouse Electric Company LLC

Nuclear Power PlantsPost Office Box 355

Pittsburgh, PA 15230-0355

2007 Westinghouse Electric Company LLC All Rights Reserved

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NGNP and Hydrogen Production Preconceptual Design Report NGNP-20-RPT-003 Special Study 20.3 – High Temperature Process Heat Transfer and Transport

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LIST OF CONTRIBUTORS

Name and Company Date

Scott Penfield, Dan Allen, George Hayner, Fred Silady, and Dan Mears - Technology Insights

Michael Correia, Renee Greyvenstein - Pebble Bed Modular Reactor (Proprietary) Ltd.

Jan van Ravenswaay - M-Tech Industrial (Pty) Ltd.

25 Jan 2007

BACKGROUND INTELLECTUAL PROPERTY CONTENT

Section Title Description

None None

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REVISION HISTORY

RECORD OF CHANGES

Revision No. Revision Made by Description Date

0 Scott R. Penfield, Jr., PE

Technology Insights Initial Issue

DOCUMENT TRACEABILITY

Created to Support the Following

Document(s)

Document Number Revision

NGNP and Hydrogen Production Preconceptual Design Report

NGNP-01-RPT-001 0

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LIST OF TABLES

Table 1 HTS Evaluation Criteria................................................................................... 15 Table 2 Summary of SHTS Working Fluid Evaluation Results ................................... 19 Table 3 Summary of Design Tradeoffs for Evaluated HX Types................................. 22 Table 20.3.1-1 Key Commercial Application Parameters for Hydrogen Production .............. 31 Table 20.3.1-2 Representative HTS Functions and Requirements........................................... 33 Table 20.3.1-3 Comparison of Generation Plant and H2 Plant Design Duty Cycles ............... 34 Table 20.3.1-4 HTS Screening Criteria .................................................................................... 35 Table 20.3.2-1 Candidate SHTS Coolants ............................................................................... 40 Table 20.3.2-2 Helium and Candidate Liquid Salts ................................................................. 42 Table 20.3.2-3 Heat Exchangers............................................................................................... 45Table 20.3.2-4 Circulators/Pumps ............................................................................................ 47 Table 20.3.2-5 Piping and Insulation ....................................................................................... 47 Table 20.3.2-6 Valves & Seals ................................................................................................. 48Table 20.3.2-7 System Integration ........................................................................................... 50 Table 20.3.2-8 System Operation............................................................................................. 51 Table 20.3.2-9 Availability/Reliability..................................................................................... 51 Table 20.3.2-10 Safety/Licensing............................................................................................... 53Table 20.3.2-11 Economics ........................................................................................................ 53 Table 20.3.2-12 R&D Requirements.......................................................................................... 54 Table 20.3.2-13 Summary of SHTS Working Fluid Evaluation Results ................................... 55 Table 20.3.3-1 Summary of Design Tradeoffs for Evaluated HX Types................................. 71 Table 20.3.3-2 Alloys Considered for NGNP High Temperature Applications ...................... 73 Table 20.3.3-3 Refined Alloy List Based on Listing in ASME Code Section II ..................... 74 Table 20.3.3-4 Selected Properties of Alloys Evaluated .......................................................... 77 Table 20.3.3-5 Selected Properties of Alloys Evaluated .......................................................... 77 Table 20.3.3-6 ASTM Specification Range for Alloys Evaluated ........................................... 80 Table 20.3.3-7 Major Sources of Creep Data for Alloy 617 .................................................... 85 Table 20.3.3-8 Known Creep Data for Alloy 617 at about 950ºC ........................................... 85 Table 20.3.3-9 Subsection NH Materials and Maximum Allowable Times and Temperatures

........................................................................................................................ 104 Table 20.3.4-1 Option 1: Primary Brayton Cycle/GTCC, Series IHX................................... 130 Table 20.3.4-2 Option 2: Primary Brayton Cycle/GTCC, Parallel IHX ................................ 133 Table 20.3.4-3 Option 3: Secondary Brayton Cycle/GTCC, Series PCHX ........................... 134 Table 20.3.4-4 Option 4: Secondary Brayton Cycle/GTCC, Parallel PCHX......................... 136 Table 20.3.4-5 Option 5: Bottoming Steam Cycle, Series IHX ............................................. 138 Table 20.3.4-6 Option 6: Secondary Steam Cycle, Series PCHX.......................................... 140 Table 20.3.4-7 Option 7: PCS Integrated with Process.......................................................... 145 Table 20.3.4-8 Evaluation of HTS Configuration Options .................................................... 148

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LIST OF FIGURES

Figure 1 Reference Direct Brayton Cycle ...................................................................... 16 Figure 2 Reference GTCC.............................................................................................. 17 Figure 3 Representative Rankine Cycle ......................................................................... 17 Figure 4 2-Section IHX Concept .................................................................................... 25 Figure 5 Process Heat/PCS Configuration Hierarchy .................................................... 26 Figure 6 Recommended HTS Configuration.................................................................. 28 Figure 20.3.1-1 PBMR PHP for Hydrogen Production via HyS ............................................... 31 Figure 20.3.1-2 Sources of HTS Functional Requirements....................................................... 33 Figure 20.3.1-3 Reference Direct Brayton Cycle ...................................................................... 36 Figure 20.3.1-4 Reference GTCC.............................................................................................. 37 Figure 20.3.1-5 Representative Rankine Cycle ......................................................................... 37 Figure 20.3.2-1 Reference PBMR PHP for H2 via HyS Process ............................................... 44 Figure 20.3.2-2 Alternate HyS Process Coupling...................................................................... 44 Figure 20.3.3-1 Example of Tube and Shell Heat Exchanger with Straight Tubes ......... 65 Figure 20.3.3-2 Example of Tube and Shell Heat Exchanger with Helical Tubes .......... 66 Figure 20.3.3-3 Compact Heat Exchanger Performance...................................................... 68 Figure 20.3.3-4 Brazed Plate-Fin Recuperator Cross-Section................................................... 68 Figure 20.3.3-5 Plate-Fin Recuperator Assembly...................................................................... 69 Figure 20.3.3-6 Corrugated Foil Pattern for Primary Surface Recuperator............................... 69 Figure 20.3.3-7 Cross-section through Heatric PCHE ......................................................... 70 Figure 20.3.3-8 Flow Path through PCHE ............................................................................. 70 Figure 20.3.3-9 Comparison of Creep Rupture Life to Failure for Alloys Evaluated............... 79 Figure 20.3.3-10 Creep Rupture Data That Compares Alloy 617 and 617CCA ......................... 81 Figure 20.3.3-11 Creep Rupture Data That Compares Alloy 617 and 617CCA ......................... 82 Figure 20.3.3-12 Creep Strain vs. Time for 3 Alloy 617 Heats in Helium at 13.5MPa Stress.... 82 Figure 20.3.3-13 Elongation at Rupture vs. Temperature for 3 Alloy 617 Heats in Air and

Impure Helium ................................................................................................. 83 Figure 20.3.3-14 Recent Alloy 230 High Temperature Creep Rupture Life Data Compared to

Hastelloy XR.................................................................................................... 83 Figure 20.3.3-15 Recent Alloy 230 High-Temperature Creep Rupture Life Data vs. Alloy 617 84 Figure 20.3.3-16 Average Alloy 230 and 617 INCO and Haynes Creep Rupture Data at High

Temperatures for Long Times.......................................................................... 84 Figure 20.3.3-17 Hastelloy X Exposure with Relatively Little Cr Oxide Formation.................. 87 Figure 20.3.3-18 Alloy 800H Exposure with Relatively Greater Cr Oxide and Ti Oxide

Formation and Some Internal Oxidation of Al ................................................ 87 Figure 20.3.3-19 Alloy 617 Exposure with Cr Oxide and Ti Oxide Formation Similar to Alloy

800H and Some Internal Oxidation of Al ........................................................ 88 Figure 20.3.3-20 Summary of French He Test Data at 950ºC and 813 Hours ............................ 88 Figure 20.3.3-21 AGATA Cordierite Plate Type HX ................................................................. 93 Figure 20.3.3-22 GTE Ceramic Recuperator Matrix ................................................................... 94 Figure 20.3.3-23 Representative NHI Ceramic Heat Exchanger Concepts................................. 97 Figure 20.3.3-24 Typical Curves for Sm and St ........................................................................ 106 Figure 20.3.3-25 ASME Figure 20.3.T-1420-2 Creep-Fatigue Damage Envelope................... 109 Figure 20.3.3-26 Current ASME/DOE Project Organization.................................................... 113

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Figure 20.3.3-27 Planned Test Points for Alloy 617 at 850ºC .................................................. 121 Figure 20.3.3-28 Planned Test Points for Alloy 617 at 950ºC .................................................. 121 Figure 20.3.3-29 2-Section IHX Concept .................................................................................. 124 Figure 20.3.4-1 Process Heat/PCS Configuration Hierarchy .................................................. 129 Figure 20.3.4-2 Option 1: Primary Brayton Cycle/GTCC, Series IHX................................... 130 Figure 20.3.4-3 Option 2: Primary Brayton Cycle/GTCC, Parallel IHX ................................ 133 Figure 20.3.4-4 Option 3: Secondary Brayton Cycle/GTCC, Series PCHX ........................... 134 Figure 20.3.4-5 Option 4: Secondary Brayton Cycle/GTCC, Parallel PCHX......................... 136 Figure 20.3.4-6 Option 5: Bottoming Steam Cycle, Series IHX ............................................. 137 Figure 20.3.4-7 Option 6: Secondary Steam Cycle, Series PCHX.......................................... 139 Figure 20.3.4-8 Cycle L: Rankine Cycle Parameters for 0-10 MW H2 Plant Size.................. 141 Figure 20.3.4-9 Cycle L: Rankine Cycle Parameters for 200 MW H2 Plant Size ................... 142 Figure 20.3.4-10 Cycle L: Influence of Hydrogen Plant Size ................................................... 143 Figure 20.3.4-11 Pinch Temperature Allows H2 Plant Sizes Up to ~200 MW ......................... 143 Figure 20.3.4-12 Option 7: PCS Integrated with Process.......................................................... 144 Figure 20.3.4-13 Recommended HTS Configuration: Option 6 ............................................... 147

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ACRONYMS

AGATA European Advanced Gas Turbine for Automobiles ASME American Society of Mechanical Engineers ASTM American Society of Testing and Materials BOP Balance of Plant BNCS ASME Board on Nuclear Codes and Standards C-C Carbon/Carbon Composites CFRC Carbon Fiber Reinforced Carbon CRBRP Clinch River Breeder Reactor Plant CTE Coefficient of Thermal Expansion DDN Design Data Needs DOE US Department of Energy dP Pressure difference between primary and secondary or between the IHX internal

channels and the exterior surfaces of the HX DPP Demonstration Power Plant EOFY End of Fiscal Year ESR Electro-slag Re-melting FEA Finite Element Analysis GA General Atomic GIF Generation IV International Forum GS Grain Size GT Gas Turbine GTCC Gas Turbine Combined Cycle HPU Hydrogen Production Unit HT High Temperature HTE High Temperature Electrolysis HTGR High Temperature Gas-Cooled Reactor HTR High Temperature Reactor (Germany) HTR-10 High Temperature Test Reactor (Chinese) HTS Heat Transport System HTTR High Temperature Test Reactor (Japanese) HX Heat Exchanger HyS Hybrid Sulfur System for Hydrogen Production IHX Intermediate Heat Exchanger INL Idaho National Laboratory ITRG Independent Technology Review Group JAEA Japan Atomic Energy Agency LCF Low Cycle Fatigue MIT Massachusetts Institute of Technology NERAC Nuclear Energy Research Advisory Committee NGNP Next Generation Nuclear Plant ORNL Oak Ridge National Laboratory PBMR Pebble Bed Modular Reactor PCHE Printed Circuit Heat Exchanger

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PCHX Process Coupling Heat Exchanger PCS Power Conversion System PHTS Primary Heat Transport System PPMP Preliminary Project Management Plan for the NGNP PWHT Post Weld Heat Treatment PSR Primary Surface Reaction Type of HX Design R&D Research and Development RBSN Reaction Bonded Silicon Nitride RCC-MR French Design Code RPV Reactor Pressure Vessel SHTS Secondary Heat Transport System S-I Sulfur Iodine System for Hydrogen Production USC Ultra-Supercritical Fossil R&D Boiler Program VHTR Very High Temperature Gas-Cooled Reactor VIM Vacuum Induction Melting

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TABLE OF CONTENTS

Section Title Page

LIST OF TABLES ........................................................................................................................ 4

LIST OF FIGURES ...................................................................................................................... 5

ACRONYMS................................................................................................................................. 7

20.3 HIGH TEMPERATURE PROCESS HEAT TRANSFER AND TRANSPORT ... 13

SUMMARY AND CONCLUSIONS ......................................................................................... 13

STUDY INPUTS AND EVALUATION CRITERIA......................................................................... 13

INPUT OPTIONS....................................................................................................................... 16

Power Conversion System Options ............................................................................... 16 H2 Production Unit Size ................................................................................................ 17 SHTS Working Fluid Options ....................................................................................... 17

IHX READINESS ASSESSMENT ............................................................................................... 20

Assessment Inputs.......................................................................................................... 20 IHX Design Considerations ........................................................................................... 21 Metallic Materials Assessment ...................................................................................... 22 Ceramic Materials Assessment...................................................................................... 23 Codes and Standards Readiness..................................................................................... 23 Design Data Needs and R&D Program ......................................................................... 24 Conclusions and Recommendations .............................................................................. 24

HTS CONFIGURATION OPTIONS............................................................................................ 26

CONCLUSIONS AND RECOMMENDATIONS.............................................................................. 27

INTRODUCTION....................................................................................................................... 29

OBJECTIVE AND SCOPE .......................................................................................................... 29

ORGANIZATION OF REPORT................................................................................................... 29

20.3.1 STUDY INPUTS........................................................................................................... 30

20.3.1.1 COMMERCIAL APPLICATIONS AND PERFORMANCE REQUIREMENTS ............... 30

20.3.1.2 KEY NGNP HTS DEMONSTRATION OBJECTIVES ............................................. 30

20.3.1.2.1 IHX ........................................................................................................ 31 20.3.1.2.2 Hydrogen Production Unit..................................................................... 32 20.3.1.2.3 Licensing................................................................................................ 32 20.3.1.2.4 Other Demonstration Objectives ........................................................... 32

20.3.1.3 KEY HTS FUNCTIONAL REQUIREMENTS ........................................................... 32

20.3.1.4 SCREENING CRITERIA......................................................................................... 34

20.3.1.5 POWER CONVERSION SYSTEM OPTIONS ............................................................ 36

20.3.1.6 H2 PRODUCTION UNIT SIZE ............................................................................... 37

20.3.1.7 REFERENCES FOR SECTION 20.3.1...................................................................... 38

20.3.2 EVALUATION OF SHTS WORKING FLUID OPTIONS ..................................... 39

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20.3.2.1 FUNCTIONS .......................................................................................................... 39

20.3.2.2 INITIAL SCREENING ............................................................................................ 40

20.3.2.3 THERMOPHYSICAL PROPERTIES ........................................................................ 41

20.3.2.4 EVALUATION ....................................................................................................... 41

20.3.2.4.1 Design Compatibility............................................................................. 43 20.3.2.4.2 Influence on Major Components ........................................................... 43

20.3.2.4.2.1 Heat Exchangers...................................................................... 43 20.3.2.4.2.2 Circulators/Pumps ................................................................... 46 20.3.2.4.2.3 Piping and Insulation............................................................... 46 20.3.2.4.2.4 Valves and Seals...................................................................... 46

20.3.2.4.3 System Integration ................................................................................. 49 20.3.2.4.4 System Operation................................................................................... 49 20.3.2.4.5 Availability and Reliability.................................................................... 49 20.3.2.4.6 Safety & Licensing ................................................................................ 52 20.3.2.4.7 Economic Considerations ...................................................................... 52 20.3.2.4.8 R&D Requirements................................................................................ 52

20.3.2.5 EVALUATION AND RECOMMENDATION .............................................................. 55

20.3.2.6 REFERENCES FOR SECTION 20.3.2...................................................................... 57

20.3.3 IHX READINESS ASSESSMENT ............................................................................. 58

20.3.3.1 INTRODUCTION.................................................................................................... 58

20.3.3.1.1 Purpose................................................................................................... 58 20.3.3.1.2 Scope...................................................................................................... 58 20.3.3.1.3 Outline ................................................................................................... 59

20.3.3.2 INDEPENDENT TECHNOLOGY REVIEW GROUP RECOMMENDATIONS

ASSOCIATED WITH THE IHX............................................................................... 59

20.3.3.2.1 Upper Temperature Limit ...................................................................... 59 20.3.3.2.2 Pressure Boundary Time-Dependent Deformation................................ 60 20.3.3.2.3 ASME Codes and Standards.................................................................. 61 20.3.3.2.4 Corrosion and Oxidation........................................................................ 61 20.3.3.2.5 Microstructural Stability ........................................................................ 62 20.3.3.2.6 Advanced Materials Development......................................................... 62 20.3.3.2.7 Summary Observations Regarding ITRG Report.................................. 63

20.3.3.3 DEFINITION OF “HIGH TEMPERATURE” FOR METALLIC MATERIALS ............. 63

20.3.3.4 ASSESSMENT INPUT REQUIREMENTS ................................................................. 64

20.3.3.5 IHX DESIGN CONSIDERATIONS .......................................................................... 64

20.3.3.6 METALLIC MATERIALS ASSESSMENT ................................................................ 71

20.3.3.6.1 Evaluation of Specific High Temperature Alloys.................................. 72 20.3.3.6.1.1 Haynes 556.............................................................................. 72 20.3.3.6.1.2 Haynes 230.............................................................................. 74 20.3.3.6.1.3 Hastelloy X and XR ................................................................ 75 20.3.3.6.1.4 Inconel 617 and 617CCA........................................................ 75 20.3.3.6.1.5 Haynes HR-120 ....................................................................... 75 20.3.3.6.1.6 Haynes RA-330 ....................................................................... 76 20.3.3.6.1.7 Alloy 800H.............................................................................. 76

20.3.3.6.2 Further Evaluation of Alloys ................................................................. 76

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20.3.3.6.3 Other Considerations ............................................................................. 90 20.3.3.6.4 Final Recommendations ........................................................................ 90

20.3.3.7 CERAMICS MATERIALS ASSESSMENT ................................................................ 91

20.3.3.7.1 Historical Background ........................................................................... 91 20.3.3.7.2 Examples of Ceramic Recuperators for Small Turbines ....................... 93 20.3.3.7.3 Materials Selection ................................................................................ 94 20.3.3.7.4 Fabrication Methods .............................................................................. 96 20.3.3.7.5 NHI Ceramic Heat Exchanger Initiatives .............................................. 96 20.3.3.7.6 Ceramic HX Summary........................................................................... 97

20.3.3.8 CODES AND STANDARDS READINESS .................................................................. 99

20.3.3.8.1 Historical Background ........................................................................... 99 20.3.3.8.2 ASME Board on Nuclear Codes and Standards (BNCS) .................... 100 20.3.3.8.3 Basic ASME Code Definitions ............................................................ 101 20.3.3.8.4 Classification of Stresses ..................................................................... 101 20.3.3.8.5 ASME Section III, Subsection NB (Elastic Analysis)......................... 103 20.3.3.8.6 ASME Section III, Subsection NH (Elastic/Inelastic Analysis).......... 104 20.3.3.8.7 ASME Section III, Subsection NH Design Issues............................... 107 20.3.3.8.8 ASME Section VIII Issues................................................................... 109 20.3.3.8.9 DOE Initiative to Address ASME Code Issues ................................... 110

20.3.3.8.9.1 Funded Tasks......................................................................... 110 20.3.3.8.9.2 Unfunded Tasks..................................................................... 113 20.3.3.8.9.3 Project Organization.............................................................. 113

20.3.3.8.10 ASME Draft Code Case for Alloy 617................................................ 114 20.3.3.8.11 Summary and Recommendations ........................................................ 115

20.3.3.9 DESIGN DATA NEEDS AND R&D PROGRAM..................................................... 116

20.3.3.9.1 Introduction.......................................................................................... 116 20.3.3.9.2 Design Data Needs for Materials......................................................... 118

20.3.3.9.2.1 Thermal Physical & Mechanical Properties DDNs............... 118 20.3.3.9.2.2 Weldability DDNs................................................................. 119 20.3.3.9.2.3 Aging of Ni-based Alloys DDNs .......................................... 119 20.3.3.9.2.4 Exposure to Impure He at Elevated Temperatures up to 1000ºC

DDNs............................................................................................ 120 20.3.3.9.2.5 Grain Size Effects DDNs ...................................................... 120

20.3.3.9.3 Design Basis Information DDNs ......................................................... 120 20.3.3.9.4 IHX Performance Verification DDNs ................................................. 122

20.3.3.10 IMPLICATIONS FOR THE NGNP PRE-CONCEPTUAL DESIGN ........................... 122

20.3.3.11 FINAL CONCLUSIONS AND RECOMMENDATIONS ............................................. 123

20.3.3.12 REFERENCES FOR SECTION 20.3.3.................................................................... 126

20.3.4 HTS CONFIGURATION OPTIONS ....................................................................... 129

20.3.4.1 DIRECT CYCLE PCS OPTIONS.......................................................................... 129

20.3.4.1.1 Option 1: Primary Brayton Cycle/GTCC, Series IHX ........................ 129 20.3.4.1.2 Option 2: Primary Brayton Cycle/GTCC, Parallel IHX...................... 132

20.3.4.2 INDIRECT CYCLE PCS OPTIONS....................................................................... 132

20.3.4.2.1 Option 3: Secondary Brayton Cycle/GTCC, Series PCHX................. 132 20.3.4.2.2 Option 4: Secondary Brayton Cycle/GTCC, Parallel PCHX .............. 135

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20.3.4.2.3 Option 5: Bottoming Steam Cycle, Series IHX................................... 135 20.3.4.2.4 Option 6: Secondary Steam Cycle, Series PCHX................................ 138

20.3.4.3 INTEGRATED PCS/PROCESS OPTIONS – OPTION 7 .......................................... 144

20.3.4.4 EVALUATION AND RECOMMENDATION ............................................................ 146

20.3.4.5 REFERENCES FOR SECTION 20.3.4.................................................................... 147

REFERENCES.......................................................................................................................... 149

BIBLIOGRAPHY..................................................................................................................... 149

DEFINITIONS .......................................................................................................................... 149

REQUIREMENTS.................................................................................................................... 149

LIST OF ASSUMPTIONS....................................................................................................... 149

TECHNOLOGY DEVELOPMENT ....................................................................................... 149

APPENDICES........................................................................................................................... 150

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20.3 HIGH TEMPERATURE PROCESS HEAT TRANSFER AND TRANSPORT

SUMMARY AND CONCLUSIONS

This report documents the NGNP Special Study on high temperature process heat transfer and transport. The objective of this study was to select a reference configuration for the NGNP Heat Transport System (HTS). The selection of a reference HTS configuration is, by necessity, accomplished in close coordination with the NGNP special studies addressing the Power Conversion System (PCS) and Hydrogen Production Unit (HPU).

In accomplishing the study objective, the first step was to obtain necessary study inputs. Included in such inputs are commercial applications, along with their respective performance requirements. Support for the development and commercialization of these applications is the ultimate purpose of the NGNP demonstration. Closely related are NGNP demonstration objectives, which derive from the needs of the supported commercial applications. Also related, at a more detail level, are key functional requirements that must be fulfilled by the HTS. Finally, criteria for screening of HTS options and selection of a reference HTS configuration were developed from a consideration of all of the above.

In addition to these external inputs, two key inputs were obtained from companion NGNP special studies. These are the PCS options to be considered in conjunction with the HPU, and the minimum size and range of potential sizes of the HPU itself.

The NGNP Heat Transport System special study includes two important sub-studies that have a significant bearing on HTS configuration options. The first is an evaluation of prospective Secondary Heat Transport System (SHTS) working fluids. The second is a specific evaluation of design and materials readiness for the Intermediate Heat Exchanger (IHX), a key HTS component. Note that the Process Coupling Heat Exchanger (PCHX), which transfers thermal energy to the PCS, is common to all HTS configuration options and, as such, was not directly assessed in this special study.

With the above elements in hand, a number of specific HTS configuration options were evaluated and a recommendation provided.

Study Inputs and Evaluation Criteria

Three hydrogen production options were considered in establishing the commercial performance requirements to be supported by the NGNP. The first is the Hybrid Sulfur (HyS) process, which is the present basis for the Pebble Bed Modular Reactor (PBMR) Process Heat Plant (PHP) for hydrogen production. The other processes, the Sulfur-Iodine (S-I) cycle and High Temperature Electrolysis (HTE), have not yet been specifically optimized for the PBMR PHP. The principal requirements influencing the HTS configuration are process temperature and thermal power. Common to all three applications is a requirement for high temperatures within

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the process, ranging from 900ºC to 925ºC. The corresponding reactor outlet temperature is 950ºC in all cases. In both the HyS and S-I commercial applications, all of the energy produced in the reactor is routed via the IHX to the process and/or power conversion section. In the case of HTE, only a small fraction (~10%) of the total reactor energy is needed as heat in the process.

Electric generation applications of high temperature gas cooled reactors (HTGRs) either have been demonstrated or will be demonstrated through the South African Demonstration Power Plant (DPP). In this context, the principal mission of the NGNP must be to demonstrate and support commercial process heat applications of the HTGR, notably including hydrogen production. If this mission is to be fulfilled, there are three critical corollary objectives that must be attained:

1. Intermediate Heat Exchanger (IHX) - Demonstration of a reliable IHX with acceptable performance and lifetime is viewed as one of the most important technical barriers to commercial high-temperature process heat applications and a critical objective of the NGNP demonstration.

2. Hydrogen Production Unit (HPU) - A critical incremental contribution of the NGNP will be demonstration of the integration of one or more HPUs with a nuclear heat source. This will provide the basis for confirming the design and licensing of future commercial plants. Note that a unique differentiating requirement for the NGNP is providing the flexibility to demonstrate multiple processes.

3. Licensing/Design Certification - Demonstration of the licensing process as it pertains to process heat applications, specifically including hydrogen production, is viewed as being particularly important in support of commercial process heat applications. In all likelihood, such demonstration is a prerequisite for private sector investment in follow-on commercial plants.

For each of these three critical objectives, it is essential that the NGNP provide an adequate basis for the deployment of commercial plants without the need for further demonstration.

Functional requirements provide further inputs. Key HTS functions include:

Transport and transfer of thermal energy from the reactor to the HPU and PCS during normal operation and to alternate heat sinks during other operating modes and transients.

Control of radionuclides (e.g., integrity of pressure boundaries, tritium transport)

Protection of the Nuclear Heat Source (NHS) from process-related hazards

Based on all of the above inputs, evaluation criteria for selection of the NGNP HTS configuration were selected and are summarized in Table 1

The category of Readiness refers to the ability of the selected HTS to support NGNP objectives within the specified schedule which calls for startup within the 2016 to 2018

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timeframe. In addition to the overt criterion relating to the ability to meet the NGNP timeline, which is highly weighted, two additional readiness criteria are identified. The first relates to R&D requirements and their associated costs and risk. Such R&D requirements can be thought of as an indirect measure of the likelihood of attaining NGNP goals in a timely manner. Also related is the ability of the vendor/supplier/regulatory infrastructure to support NGNP

Table 1 HTS Evaluation Criteria

Attribute Importance

Readiness

Ability to meet NGNP timeline (startup: 2016-2018) High

NGNP R&D Requirements/Cost/Risk Med

Vendor/Supplier Infrastructure Development Med

Support of Commercial Applications

Adequately demonstrates commercial process heat

applicationsHigh

NHS commonality with commercial products High

Can serve as process heat prototype for design certification High

Flexibility for demonstrating advanced applications Med

Flexibility for ultimate NGNP conversion to full-scale H2 production

Med

Performance

Ability to meet operational performance goals High

Overall Plant Efficiency Low

Operability Med

Availability Low

Cost

NGNP Capital Cost High

NGNP Operating Cost Low

requirements. To the extent that such infrastructure is not in place, or cannot be put in place in a timely manner, the risk to the NGNP objectives and schedule are increased. Since there is some overlap, the latter two criteria are given a medium weighting.

As stated above, the demonstration of commercial process heat applications is the principal mission of the NGNP. This is reflected in the high importance weighting of the first three criteria in this category. The third criterion, support of commercial process heat plant design certification, is viewed as particularly important.

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In the category of Performance, the ability to meet operational performance goals (e.g., the provision of thermal energy to the process at required temperatures and thermal capacities with high reliability) is considered essential to the mission of the NGNP. Overall plant efficiency and availability are rated low, in recognition that compromises may be required to provide the flexibility for testing of multiple hydrogen production options, and that availability will be impacted by both testing requirements and equipment change out as different HPU options are tested. Operability is rated as medium in importance, recognizing that such operability will be optimized through experience gained with the NGNP.

The capital cost of the NGNP is given a high weighting, recognizing that the difficulty of obtaining public and congressional support for the NGNP Project will increase with capital cost.Operating costs are given a low weighting, again anticipating the expected impacts of testing and equipment change out.

Input Options

Power Conversion System Options

Power conversion system options were evaluated in a separate NGNP special study. Reference configurations were identified for the direct Brayton cycle, GTCC and Rankine cycle options.

The reference direct Brayton cycle is a single shaft recuperated and intercooled configuration, as shown in Figure 1. The reference GTCC incorporates a recuperated Brayton topping cycle with a single stage of compression and a bottoming Rankine cycle, as shown in Figure 2. A representative Rankine cycle was selected, as shown in Figure 3.

RHX

Precooler

Intercooler

PT ~GBLPC HPC

To Reactor

From Reactor

RHX

Precooler

Intercooler

PT ~GBLPC HPC

RHXRHX

Precooler

Intercooler

PT ~GBLPC HPC

Intercooler

PT ~GBLPC HPC PT ~GBLPC HPC

To Reactor

From Reactor

Figure 1 Reference Direct Brayton Cycle

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PT ~GBCOMP

SG

HPT IPT LPT ~

RHX

Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

To Reactor

From Reactor

PT ~GBCOMP

SG

HPT IPT LPT ~

RHX

Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

PT ~GBCOMP PT ~GBCOMP

SGSG

HPT IPT LPT ~

RHXRHX

Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

To Reactor

From Reactor

Figure 2 Reference GTCC

SG

HPT IPT LPT ~

Ble

ed

Flo

wB

lee

d F

low

Condenser

From Heat Source

To Heat Source

SG

HPT IPT LPT ~

Ble

ed

Flo

wB

lee

d F

low

CondenserSGSG

HPT IPT LPT ~

Ble

ed

Flo

wB

lee

d F

low

Condenser

From Heat Source

To Heat Source

Figure 3 Representative Rankine Cycle

H2 Production Unit Size

The range of sizes potentially required for the hydrogen production unit (HPU) was evaluated in a separate NGNP special study. As a result of that study, the minimum size that would allow scale up of the most critical components to commercial size for the applications evaluated was determined to be ~5 MWt. An alternate approach to HPU sizing would be demonstration of a single train of a commercial HPU. For this option, it was determined that approximately 50 MWt would be required. It is further noted that the thermal rating of the high temperature PCHX for the HyS process is approximately 200 MWt.

SHTS Working Fluid Options

Four candidate SHTS working fluids were analyzed and compared as part of the overall NGNP Heat Transport System special study. Fluids evaluated included helium, carbon dioxide

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(CO2), which is used in British gas-cooled reactors, liquid salts and liquid metals. In terms of performance, the key differentiating characteristics among candidate fluids are the fluid state (gas or liquid), volumetric heat capacity and thermal conductivity. Other factors being equal, pumping power requirements will be higher for a gas than for an incompressible liquid. Volumetric heat capacity is a measure of the thermal energy that can be carried per unit volume. Higher volumetric heat capacity implies reduced pumping power requirements and/or smaller pipes or ducts. Thermal conductivity is an important determinant of heat exchanger size.

Beyond these performance characteristics, a major design consideration is the adequacy of obtainable and developed compatible materials. This concern raises issues of economics and of requirements for further development. Other issues related to the fluid selection include operational considerations (implications for duty cycle, availability, reliability & investment protection), economics and regulatory/licensing implications.

As a first step in the selection process, liquid metal was eliminated from further consideration. There are potential liquid metal candidates having melting and boiling temperatures suitable for coupling with high temperature process applications. However, there is no experience with these liquid metals in the temperature range of interest, and input from ORNL suggests that compatibility with materials at high temperatures is problematical. Above 600°C corrosion becomes a major issue.

The remaining candidates, Helium, CO2 and Liquid Salts (LS) were compared on the basis of the attributes summarized in Table 2.

The most significant factors and bases for a tradeoff decision are summarized as follows:

LS has a much higher volumetric heat capacity ( •CP) than helium or CO2, and this

implies reduced piping diameters and lower SHTS pumping power requirements, on the

order of 1/5th that for helium. The volumetric heat capacity of CO2 is about twice that of

helium, with a corresponding reduction in pumping power requirements at equivalent

temperatures and pressures.

LS has a much higher thermal conductivity than helium or CO2, which translates to

higher heat transfer coefficients and reduced log-mean temperature difference (LMTD)

requirements that can be taken advantage of in terms of either lower reactor outlet

temperature for a given process temperature or higher process temperatures for increased

efficiency and smaller heat exchangers. The thermal conductivity of CO2 is only about

1/6 that of helium, implying significantly larger and more expensive heat exchangers

with CO2.

Experience with CO2 and LS heat transport fluids has not extended to the temperature

range of the NGNP SHTS.

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Table 2 Summary of SHTS Working Fluid Evaluation Results

Item Helium CO2 LS

Design Compatibility + - - -

Influence on Major Components

Heat Exchangers + - +/-

Circulators/Pumps - + ++

Piping and Insulation ++ + - -

Valves and Seals - - - +

System Integration + - - -

System Operation + - - -

Availability and Reliability + - - -

Safety & Licensing +/- - +/-

Economic Considerations +/- +/- +

R&D + - - -

There is a requirement for an alternate heat source of undetermined size for startup of a

LS heat transport circuit, and to avoid freeze-up there needs to be a drain, storage and

vent system for LS.

The LS heat transport pressure-retaining pipes will have to operate at LS temperatures,

unless an internal insulating system can be devised - this implies a new piping material.

Therefore, insulation to limit heat loss will be external to the pipe. On the other hand,

heat losses will be reduced with LS, due to the smaller required pipe sizes. With helium

or CO2, internal insulation is possible and the pipe can run nearer to external ambient

temperature. Helium and CO2 working fluids are compatible with an optional

configuration of coaxial Secondary Heat Transport System (SHTS) transport pipes.

LS is not compatible with conventional shell and tube PCHXs that have the process fluid

and catalyst on the inside of the tubes. For a given heat delivery, the flow rate on the LS

side would be much smaller than that on the process side, leading to issues with shell side

flow distribution. With compact heat exchangers, there is a lower limit to the size of flow

passages, below which plugging can be a concern, and this limit is more likely

encountered in the smaller passages of HXs with LS.

With LS as the SHTS working fluid, any detectible leak in the IHX or PCHX will require

immediate shut-down for repairs, while continued operation is feasible with small leaks

in the IHX of an all-helium heat transport system. With CO2, leaks would also require

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immediate shutdown for repair; however, the consequences of leaks are unlikely to be as

severe as those with LS.

R&D will be required for any of the three SHTS working fluid candidates. Of the three,

helium has the fewest R&D requirements. Assuming that metallic heat exchangers are

determined to be feasible, CO2 would have modest incremental R&D needs relative to

helium. The LS alternative will almost certainly require a ceramic/CFRC IHX, and has

unique R&D needs in the areas of piping materials compatibility, piping insulation

design, high-temperature pumps and pump and valve seals. LS R&D requirements are

not compatible with the present schedule for the NGNP.

The conclusion of this evaluation was that helium should be selected as the SHTS working fluid for the NGNP and that the PCHX should be located as close to the IHX as possible. There should be continued following of LS heat transport system development with a view to future distributed process heat applications (e.g., energy parks), where longer distance high-temperature process energy transport is mandatory. As noted in the preceding section addressing study inputs, a differentiating requirement of the NGNP is to provide flexibility for demonstrating various energy utilization options. If future demonstration of LS thermal energy transport in the NGNP environment is desired, an option is to replace the PCHX with a secondary IHX and to add a tertiary LS loop to transport energy to a more distant location.

IHX Readiness Assessment

In the Study Inputs and Evaluation Criteria, summarized above, the IHX was identified as a critical demonstration objective of the NGNP. It was recognized early in the planning process that the technical barriers associated with the IHX also have the potential to drive the NGNP schedule and significantly influence decisions regarding the overall configuration of the HTS.

For these reasons, a supporting assessment was undertaken to evaluate IHX design options and issues, identify and evaluate potential metallic and ceramic IHX fabrication materials and to determine the status of applicable codes and standards. For identified shortcomings of the technology base, Design Data Needs (DDNs) and associated R&D implications for the NGNP were determined and overall conclusions and recommendations were developed regarding the readiness of the materials for the IHX.

Assessment Inputs

High-temperature components, and specifically the IHX, featured prominently in the review by the Independent Technology Review Group (ITRG) in 2004. The ITRG review was undertaken to provide a critical review of the proposed NGNP project and identify areas of R&D that needed attention. The implications of the ITRG review for the IHX are summarized as follows:

The reactor outlet temperature for the NGNP should not exceed 950ºC, based in part on IHX materials considerations.

Non-replaceable metallic components designed for the full plant lifetime (60 years) should be limited to ~900ºC. Metallic components operating at

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temperatures higher than ~900ºC, notably including high-temperature sections of the IHX, are likely to have reduced lifetimes and should be designed for replacement.1

Time-dependent deformation for Class 1 pressure boundary components should be “insignificant”, as defined by the ASME Code.

The IHX should be designed to minimize stresses imposed on the metallic alloy due to the low margin of allowable creep stress associated with available metallic alloys operating in the 900-950ºC temperature range.

Metallic materials should be limited to alloys listed in ASME Section II for Section III or Section VIII service.

Based on the requirements of commercial applications, the ITRG recommendations, above, and input from the separate NGNP Special Study on the HPU, the key assumptions and parameters used in the assessment of IHX designs and materials are as follows:

Nominal 950ºC reactor outlet temperature (ROT)

Nominal 900ºC secondary IHX outlet temperature

He in primary and secondary loops

Primary loop pressure - 9 MPa

Primary to secondary loop delta P - essentially pressure balanced

Order for IHX component by end of fiscal year (EOFY) 2012

Design life for replaceable components greater than or equal to 10 years with a target of 20 years (depending on size, design and other factors)

Target operating capacity - 95%

IHX Design Considerations

Both conventional shell-and-tube and compact heat exchangers were considered in this assessment. The most significant issues with shell-and-tube HXs are their size and weight. A 10MWt prototype IHX for the German process heat program was fabricated in the 1980s, satisfied all specified parameters and operated in excess of 900ºC ; however, the unit weighed about 135 tons. A corresponding unit for an indirect cycle 400-500MWt NGNP would be too large to be considered a viable option. Compact heat exchangers typically provide at least an order of magnitude improvement in surface compactness (m2/m3) and heat transfer compactness (MWt/m3) relative to shell-and-tube heat exchangers.

A summary of design tradeoffs for the evaluated heat exchanger designs is provided in Table 3. Taking into account these tradeoffs, the Printed Circuit Heat Exchanger (PCHE) has been selected on a preliminary basis for the NGNP IHX pre-conceptual design. The shell & tube

1 Based on the present assessment, it is recommended that non-replaceable components be limited to ~850ºC.

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HX was eliminated as not being commercially viable for a large IHX. The PCHE was judged to be more robust than other compact designs with a solid basis of commercial experience, albeit at lower temperatures. Tradeoffs include: (1) More difficult inspection and maintenance, and (2) Need to establish design basis for Code acceptance. Additional discussion regarding materials and code issues is given later.

Table 3 Summary of Design Tradeoffs for Evaluated HX Types

Metric Shell & Tube Plate-Fin & Prime Surface PCHE

Compactness (m

2/m

3 & MW/m

3 )

Poor Best Good

Cost (tons/MWt) Poor: (13.5 tons/MWt) Unlikely to be commercially viable

Best: Most compact, least materials

Good: (0.2 tons/MWt) Estimated to be ~1/68 that of S&T

Experience Base HTTR, German PNP Development

Conventional GT recuperators

PBMR DPP Recuperator, other commercial products

Robustness Best: Simple cylindrical geometry, stress minimized in HT area

Worst: Thin foils; stressed welds in pressure boundary; stress risers in pressure boundary welds; Small material and weld defects more significant

Good: Thicker plates; local debonding does not immediately affect pressure boundary; potential for higher transient thermal stresses vs. P-F

Inspection and Maintenance

Design facilitates inspection and plugging of individual tubes

Inspection and maintenance difficult or impractical below module level

Inspection and maintenance difficult or impractical below module level

HX Integration Headers and HX-vessel integration demonstrated

More difficult HX integration with multiple series/parallel modules

More difficult HX integration with multiple series/parallel modules

Code Basis for Design

Existing Sect VIII Code basis for tubular geometries

No existing Code basis No existing Code basis

Metallic Materials Assessment

A large number of metallic alloys that could be potentially useful for VHTR IHX fabrication were evaluated as a part of the NGNP Materials Program. Most of the alloys evaluated are not ASME Code materials and some are specialty alloys that may not be generally available in multiple forms. Most of the alloys evaluated also had a limited database and are not considered mature (those that have been used in multiple high temperature applications for many years). Some of the alloys evaluated were ASME Code materials, have reasonably large databases and have been used for multiple high temperature applications. Most of the alloys evaluated had no existing database for high temperature impure helium exposure.

From this larger database, the subset of alloys presently included in the ASME Code was selected for further detailed evaluation against the specific requirements of the NGNP IHX. The final conclusion of this evaluation was that if maximum mechanical properties are required at high temperature for the IHX design, Alloy 617 is the best IHX alloy option. There are unverified indications that the more restrictive chemistry of the Alloy 617CCA specification developed through the USC Program may result in improved properties relative to the standard Alloy 617 specification. This should be verified. If slightly less tensile and creep strength could be tolerated at high temperature in the IHX design, Alloy 230 may become the best IHX alloy option on the basis of lower Co content and superior resistance to helium impurities.

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Existing metallic materials can be applied in the temperature regime of the NGNP IHX, albeit with significant limitations:

Will require designs based on very low stresses during normal long-term operation

Transient-related stresses will be more significant in compact IHXs (needs further evaluation)

Likely need to replace IHX core multiple times over 60-year design life of plant

Ceramic Materials Assessment

Present metallic materials are likely not the optimum long-term solution for commercial process heat plants operating in the NGNP temperature range. For this reason, ceramic and composite materials were also evaluated.

The primary issues associated with a ceramic IHX are very high cost (for SiC or Si3N4),lack of standardization, lack of ASME Code acceptance, lack of a design basis, and the scale-up requirements for the NGNP application. For composites, fabrication technology and the establishment of a leak tight pressure boundary are additional concerns. Virtually all experts in this area agree that a ceramic or composite IHX is not a viable option for the timeframe of the NGNP initial deployment.

However, the limitations of metallic materials provide significant incentives for the development of ceramic heat exchangers for the IHX, as well as for the Process Coupling Heat Exchanger (PCHX), which poses additional challenges related to the process environment. It is viable to include this type of HX in a prototype testing program or to include a ceramic prototype in a side helium stream in the NGNP. This would facilitate the development of a specification, procurement for testing purposes and comparative testing with alloy prototype IHX units in a controlled loop. It is recommended that SiC or Si3N4 be used as the base ceramic for this application. While composite materials also appear to have promise, issues associated with fabrication and leakage must be solved before they can be considered viable for this application.

Codes and Standards Readiness

The availability and applicability of industrial codes and standards (e.g., ASME) was assessed as part of the overall assessment of materials readiness. Metal alloys that could potentially be used to construct the IHX are not currently a part of the ASME Nuclear Code, Section III. A significant effort will be required to resolve this issue because a reliable database potentially useful for a code case based on three well-documented heats of material is not available. There is no existing ASME Code basis (Section III or other) for the application of ceramics in pressure boundary applications. There is no existing ASME Section III design basis for either a conventional tube-and-shell IHX or less-conventional plate-type IHX, such as the PCHE. The most expedient approach for the NGNP IHX appears to be development of an application-specific design basis and submittal of a Section III code case associated with Subsection NH. A significant effort will also be required to resolve this issue, because an openly available design basis is not available in a format suitable for a code case. If a plate-type IHX is

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selected, testing of prototype IHX units would be needed to support the code case design basis for the specific IHX design selected.

The IHX for the NGNP should be contained in a Class 1 pressure boundary from an ASME Code consideration and to minimize pressure-induced stresses in the unit, because of the low metallic materials margin at 900-950ºC. A pressure boundary will be needed if a plate type HX is used, which under current rules is not a Code vessel. The pressure boundary size would be greatly reduced if a plate-type HX unit is used for the NGNP IHX. The pressure vessel(s) should be designed using ASME Section III, Subsection NB design rules (no creep) and should be insulated and cooled as required.

Design Data Needs and R&D Program

Based on the above, Design Data Needs (DDNs) were identified for the IHX and associated materials. These DDNs can be generally identified with the following categories:

Material properties data relevant to the selected alloy (presumably either Alloy 617 or 230, depending on the high temperature strength and creep requirements for the IHX design). This data would support the materials part of the directed IHX ASME Section III Code Case

Design methods and design basis information, based on detailed analysis, that would support the design part of the directed Code Case

Verification of IHX performance and structural adequacy. Fulfillment of this DDN is likely to require testing of prototype IHX units that are procured following detailed discussions and a detailed procurement specification for the IHX design selected (presumably a plate-type HX concept).

Conclusions and Recommendations

The reactor outlet temperature for the NGNP should not exceed 950ºC, based in part on IHX materials considerations.

As a result of this assessment, it is concluded that non-replaceable metallic components designed for the full plant lifetime (60 years) should be limited to ~850ºC versus 900ºC, as earlier recommended by the ITRG. Metallic components operating at temperatures higher than ~850ºC, notably including high-temperature sections of the IHX, are likely to have reduced lifetimes and should be designed for replacement.

For large IHXs, such as would be used in indirect cycle architectures, the above suggests consideration of a 2-Section IHX concept (Figure 4) in which the sections operating at the highest temperatures are separated from those operating at lower temperatures.

Time-dependent deformation for Class 1 pressure boundary components should be “insignificant”, as defined by the ASME Code.

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The IHX should be designed to minimize stresses imposed on the metallic alloy due to the low margin of allowable creep stress associated with available metallic alloys operating in the 900-950ºC temperature range

Metallic materials should be limited to alloys listed in ASME Section II for Section III or Section VIII service.

A metallic plate-type HX development program should be pursued for the NGNP IHX in conjunction with an appropriate design and materials development program.

Alloys 617 or 230 are recommended for IHX construction depending on the stress and creep requirements of the design.

NGNP-specific code cases should be developed to provide an ASME design and fabrication material basis for the NGNP IHX.

While ceramic materials hold significant future promise, their selection for the initial NGNP IHX would pose an unacceptable risk to the NGNP schedule. Nevertheless, their potential for resolving the high-temperature issues associated with metals justifies an aggressive parallel development path.

PBMR

Metal

IHX

Metalor

SiCIHX

~950ºC

~850ºC

PBMR

Metal

IHX

Metalor

SiCIHX

Metal

IHX

Metal

IHX

Metalor

SiCIHX

Metalor

SiCIHX

Metalor

SiCIHX

~950ºC

~850ºC~850ºC

Figure 4 2-Section IHX Concept

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HTS Configuration Options

A range of HTS configurations were evaluated as candidates for the NGNP preconceptual design. As shown in Figure 5, the HTS options can be generally categorized in terms of the integration of the PCS relative to the primary coolant circuit and the process coupling.

In direct PCS configuration options, the power conversion turbomachinery is located within the primary helium loop itself. In indirect PCS configuration options, the power conversion turbomachinery is isolated from the primary circuit by an intermediate heat exchanger (IHX). Indirect PCS configuration options are further categorized by whether the PCS is independently coupled to the secondary heat transport system (SHTS) circuit or integrated with the process itself. In the latter, all or part of the PCS coupling is located in the process streams beyond the process coupling heat exchanger (PCHX). This is prototypical of proposed commercial applications, including the PBMR PHP for hydrogen production via the HyS process.

PBMR

Indirect PCSDirect PCS

Brayton Cycle

Series or Parallel IHX

Process Integrated

or No PCS

Steam Cycle

Secondary PCS

Steam Cycle

Gas Turbine

Combined Cycle

Series or Parallel IHX

Brayton Cycle

Series or Parallel IHX

Gas Turbine

Combined Cycle

Series or Parallel IHX

PBMR

Indirect PCSDirect PCS

Brayton Cycle

Series or Parallel IHX

Brayton Cycle

Series or Parallel IHXSeries or Parallel IHX

Process Integrated

or No PCS

Steam CycleSteam Cycle

Secondary PCS

Steam CycleSteam Cycle

Gas Turbine

Combined Cycle

Series or Parallel IHX

Gas Turbine

Combined Cycle

Series or Parallel IHXSeries or Parallel IHX

Brayton Cycle

Series or Parallel IHX

Brayton Cycle

Series or Parallel IHXSeries or Parallel IHX

Gas Turbine

Combined Cycle

Series or Parallel IHX

Gas Turbine

Combined Cycle

Series or Parallel IHXSeries or Parallel IHX

Figure 5 Process Heat/PCS Configuration Hierarchy

The following seven candidate HTS configurations were evaluated against the criteria of Table 1.

Option 1: Primary Brayton Cycle or GTCC, Series IHX Option 2: Primary Brayton Cycle or GTCC, Parallel IHX Option 3: Secondary Brayton Cycle or GTCC, Series PCHX Option 4: Secondary Brayton Cycle or GTCC, Parallel PCHX

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Option 5: Bottoming Steam Cycle, Series IHX Option 6: Secondary Steam Cycle, Series PCHX Option 7: PCS Integrated with Process

In the course of the evaluation, it became evident that the Brayton cycle versus Gas-Turbine Combined Cycle (GTCC) tradeoff was primarily an issue of optimization, based on overall efficiency and cost. On that basis, the Brayton and GTCC alternatives were considered to be sub-options of Options 1-4.

Important differentiating factors in the evaluation are summarized as follows:

The principal demonstration objective of the NGNP has been identified as high-temperature process heat applications, notably hydrogen production. There is an incentive to reduce technical risks not directly associated with this objective. It is further noted that support for commercial electrical generation applications will be provided by the PBMR Demonstration Power Plant in South Africa.

Establishing the technology basis for the IHX is a key NGNP demonstration objective and a prerequisite for leading commercial applications. The indirect cycle architectures of Options 3, 4, 6 and 7 definitively address the IHX issue at commercial scale.

The NGNP must provide an adequate basis for licensing/design certification of follow-on commercial plants. This is also considered a prerequisite for commercial applications. The Nuclear Heat Source of the indirect cycle architectures of Options 3, 4, 6 and 7 is prototypical of proposed commercial applications and would provide an optimum basis for licensing/design certification of follow-on commercial plants. It is not clear that Options 1, 2 or 5 would provide an adequate basis for the licensing of commercial plants.

The Rankine PCS of Options 5, 6 and 7 provides maximum flexibility for demonstrating HPUs of varying size and provides an option for the ultimate conversion of the NGNP to a commercial hydrogen production facility. The characteristics of the Rankine cycle further avoid operational pressure transients that would result from a Brayton or GTCC PCS, whether located in the primary or secondary loop. Such transients may not be compatible with a metallic IHX at the temperatures of interest.

Conclusions and Recommendations

As a result of this evaluation, it is recommended that Option 6, Secondary Steam Cycle Series PCHX (Figure 6), be selected as the initial basis for the NGNP preconceptual design. As noted above, the application of a full-size IHX best represents and supports commercial designs, and provides the optimum basis for licensing/design certification of the nuclear heat source for commercial process heat applications. The Rankine cycle, which is also applied in the corresponding commercial designs, provides maximum flexibility for HPU demonstration and avoids technical risks not associated with the primary NGNP mission.

The IHX should be of a metallic plate-type design, with subdivision of the IHX into two stages by temperature. The lower temperature part would be designed as a lifetime component, while the higher temperature part would be designed for ease of replacement. An aggressive

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parallel ceramic IHX development path is recommended with the objective of replacing the higher temperature part of the IHX, when available.

PBMR

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Metal

IHX

Metalor

SiCIHX

SG

HPT IPT LPT ~

Ble

ed

Flo

wB

lee

d F

low

CondenserSGSG

HPT IPT LPT ~

Ble

ed

Flo

wB

lee

d F

low

CondenserPBMR

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Metal

IHX

Metalor

SiCIHX

Metal

IHX

Metal

IHX

Metalor

SiCIHX

Metalor

SiCIHX

Metalor

SiCIHX

SG

HPT IPT LPT ~

Ble

ed

Flo

wB

lee

d F

low

CondenserSGSG

HPT IPT LPT ~

Ble

ed

Flo

wB

lee

d F

low

Condenser

Figure 6 Recommended HTS Configuration

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INTRODUCTION

This report documents the NGNP Special Study on high temperature process heat transfer and transport.

Objective and Scope

The objective of this study is to select a reference configuration for the NGNP Heat Transport System (HTS). The selection of a reference HTS configuration is, by necessity, accomplished in close coordination with the NGNP special studies addressing the Power Conversion System and Hydrogen Production Unit.

In accomplishing the study objective, the first step was to obtain necessary study inputs. Included in such inputs are commercial applications, along with their respective performance requirements. Support for the development and commercialization of these applications is the ultimate purpose of the NGNP demonstration. Closely related are NGNP demonstration objectives, which derive from the needs of the supported commercial applications. Also related, at a more detail level, are key functional requirements that must be fulfilled by the HTS. Finally, criteria for screening of HTS options and selection of a reference HTS configuration are developed from a consideration of all of the above.

In addition to these external inputs, two key inputs are obtained from companion NGNP special studies. These are the Power Conversion System (PCS) options to be considered in conjunction with the Hydrogen Production Unit (HPU), and the minimum size and range of potential sizes of the HPU itself.

The NGNP Heat Transport System special study includes two important sub-studies that have a significant bearing on HTS configuration options. The first is an evaluation of prospective Secondary Heat Transport System (SHTS) working fluids. The second is a specific evaluation of design and materials readiness for the IHX, a key HTS component. Note that the process coupling heat exchanger (PCHX), which transfers thermal energy to the PCS, is common to all HTS configuration options and, as such, is not directly assessed in this special study.

With the above elements in hand, a number of specific HTS configuration options are evaluated and a recommendation is provided.

Organization of Report

The organization of this report follows the logic of the study that is outlined above.Study inputs, both from external sources and companion special studies, are described in Section 20.3.1. The evaluation of HTS working fluid options is documented in Section 20.3.2. The readiness of designs and materials for the IHX is documented in Section 20.3.3. The evaluation of specific HTS configuration options and the recommended HTS configuration are provided in Section 20.3.4.

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20.3.1 STUDY INPUTS

In this section, external inputs that influence the selection of the HTS configuration are first identified, and evaluated in Section 20.3.1.4, to develop screening criteria. Additional inputs from the parallel NGNP special studies addressing the Power Conversion System and Hydrogen Production Unit are summarized in Sections 20.3.1.5 and 20.3.1.6.

20.3.1.1 Commercial Applications and Performance Requirements

Commercial applications of the PBMR include both electricity production and process heat. The principal product for electricity production is the Multi-Module Power Plant (MMP).The MMP incorporates a direct Brayton cycle, and is the follow-on commercial version of the Demonstration Power Plant (DPP) that is presently in the initial stages of construction in South Africa. Consideration is also being given to gas turbine combined cycle (GTCC) options that are being addressed in a separate NGNP special study for power conversion system options.

A number of process heat applications are being evaluated for process heat plant versions of the PBMR (PBMR PHP). Among such applications are steam-methane reforming, process steam and hydrogen production. For the latter, the leading PBMR candidate is the Hybrid Sulfur (HyS) process, conceptually depicted in Figure 20.3.1-1 [Ref. 20.3.1-1]. Alternative hydrogen production concepts being evaluated by PBMR include the sulfur-iodine (S-I) process [Ref. 20.3.1-2] and high temperature electrolysis (HTE) process [Ref. 20.3.1-3]. Note that the S-I and HTE applications have not yet been specifically optimized for the PBMR PHP.

Key commercial application parameters for the Reactor/IHX and high-temperature Process Coupling Heat Exchanger (PCHX) for the three hydrogen production processes are summarized in Table 20.3.1-1. Common to all three applications is a requirement for high temperatures within the process, ranging from 900ºC to 925ºC. The corresponding reactor outlet temperature is 950ºC in all cases. In both the HyS and S-I applications, all of the energy produced in the reactor is routed via the IHX to the process and/or power conversion section. In the case of HTE, only a small fraction (~10%) of the total reactor energy is needed as heat in the process. For this reason, the configuration of [Ref. 20.3.1-3] comprises a small IHX operating in parallel with a direct Brayton cycle power conversion system.

20.3.1.2 Key NGNP HTS Demonstration Objectives

Electric generation applications of high temperature gas cooled reactors (HTGRs) either have been demonstrated or will be demonstrated through the South African DPP. Rankine cycle applications have been adequately demonstrated in earlier HTGRs, including Peach Bottom, AVR, Fort St. Vrain and THTR. The DPP, under construction in South Africa [Ref. 20.3.1-4], will provide a commercial scale demonstration of the direct Brayton cycle for electricity generation.

In this context, the principal mission of the NGNP must be to demonstrate and support commercial process heat applications of the HTGR, notably including hydrogen production. If

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PBMR IHX

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Fully Integrated PCS

SGSG

HPT LPT ~

Condenser

Preheater

Process Plant Battery Limits

PBMR IHXIHX

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Fully Integrated PCS

SGSG

HPT LPT ~

Condenser

Preheater

Process Plant Battery Limits

Figure 20.3.1-1 PBMR PHP for Hydrogen Production via HyS

Table 20.3.1-1 Key Commercial Application Parameters for Hydrogen Production

High Temp PCHX

Reactor/IHX

917925900IHX Secondary Outlet Temperature, C

950950950Core Outlet Temperature, C

10100100Fraction of Energy via IHX, %

1010036Fraction of Energy via PCHX, %

772900872Process Side Outlet Temp, ºC

57.08.8Process Pressure, MPa

Steam Generator

and Superheater

H2SO4 Vaporizer/

Decomposer

H2SO4

DecomposerHigh Temp PCHX

HTES-IHySApplication

High Temp PCHX

Reactor/IHX

917925900IHX Secondary Outlet Temperature, C

950950950Core Outlet Temperature, C

10100100Fraction of Energy via IHX, %

1010036Fraction of Energy via PCHX, %

772900872Process Side Outlet Temp, ºC

57.08.8Process Pressure, MPa

Steam Generator

and Superheater

H2SO4 Vaporizer/

Decomposer

H2SO4

DecomposerHigh Temp PCHX

HTES-IHySApplication

this mission is to be fulfilled, there are three critical corollary objectives that must be attained. These relate to the IHX, the hydrogen production unit and licensing.

20.3.1.2.1 IHX

With the exception of HTE, the commercial process heat configurations revealed to date require all of the thermal energy produced in the reactor to be routed via the IHX. At the temperatures required in leading hydrogen production processes, available metallic materials are

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marginal at peak IHX temperatures for commercially acceptable lifetimes. If metallic options are found not to be acceptable, ceramic or carbon fiber reinforced carbon (CFRC) materials may offer acceptable options, but would require significant development, and would likely be incompatible with the present NGNP schedule. Further, it is unlikely that conventional shell and tube heat exchangers would be technically or economically acceptable for commercial process heat applications due to their size and weight. The alternative is development of compact heat exchangers, which would provide an order of magnitude improvement in performance. In summary, the demonstration of a reliable IHX with acceptable performance and lifetime is viewed as one of the most important barriers to commercial process heat applications and a critical objective of the NGNP demonstration.

20.3.1.2.2 Hydrogen Production Unit

The hydrogen production unit (HPU), including the process coupling heat exchanger (PHCX) represents a second critical demonstration objective of the NGNP. Candidate HPUs, based on the HyS, S-I and HTE processes are presently being developed through the Nuclear Hydrogen Initiative (NHI). For the HyS and S-I options, the PCHX is also under development.

The critical incremental contribution of the NGNP will be demonstration of the integration of one or more of these HPUs with a nuclear heat source. This will provide the basis for confirming the design and for licensing of future commercial plants. Note that a unique differentiating requirement for the NGNP is providing the flexibility to demonstrate multiple processes.

20.3.1.2.3 Licensing

A third critical contribution of the NGNP will be demonstration of the licensing process as it pertains to process heat applications, specifically including hydrogen production. This objective is viewed as being particularly important in support of commercial process heat applications and, in all likelihood, a prerequisite for private sector investment.

20.3.1.2.4 Other Demonstration Objectives

In addition to the three critical objectives already noted, demonstration via the NGNP will provide additional confidence regarding a number of important process heat related technologies. Examples include piping and insulation, primary and secondary circulators and secondary heat transport system isolation valves, if required.

20.3.1.3 Key HTS Functional Requirements

Heat transport system (HTS) functional requirements provide another input to the HTS configuration selection process. HTS functions and requirements were addressed in a recent study of nuclear hydrogen production applications [Ref. 20.3.1-5]. As depicted in Figure20.3.1-2, functional requirements are imposed on the HTS by both the nuclear reactor and hydrogen production plant, in addition to overall plant requirements, which apply to the plant as a whole. Representative functions and requirements are provided in Table 20.3.1-2 and Table 20.3.1-3.

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NUCLEAR HEAT SOURCE

HYDROGEN

PRODUCTION

PLANT

PRIMARY

HEAT

TRANSPORT

SYSTEM

SECONDARY

HEAT

TRANSPORT

SYSTEM

NUCLEAR

REACTOR

Requirements Requirements

Plant Level

Requirements

HEAT TRANSPORT SYSTEM

NUCLEAR HEAT SOURCE

HYDROGEN

PRODUCTION

PLANT

PRIMARY

HEAT

TRANSPORT

SYSTEM

SECONDARY

HEAT

TRANSPORT

SYSTEM

NUCLEAR

REACTOR

HYDROGEN

PRODUCTION

PLANT

PRIMARY

HEAT

TRANSPORT

SYSTEM

SECONDARY

HEAT

TRANSPORT

SYSTEM

NUCLEAR

REACTOR

Requirements Requirements

Plant Level

Requirements

Plant Level

Requirements

HEAT TRANSPORT SYSTEM

Figure 20.3.1-2 Sources of HTS Functional Requirements

Table 20.3.1-2 Representative HTS Functions and Requirements

During normal operation, transport and transfer thermal energy from the reactor to the process and power conversion system (PCS), as applicable

Requirements:

Application-specific requirements: See Table 20.3.1-1

Design life: 60 years (limited life components to be replaceable)

During other normal (e.g., starting up/shutting down) and off-normal (e.g., loss of process load) operational states, transport and transfer thermal energy from the reactor to an ultimate heat sink

Requirements:

Duty Cycle: See Table 20.3.1-3

Maintain control of radionuclides

Requirements:

IHX leakage requirements

Tritium-related requirements

Protect Nuclear Heat Source from process-related hazards

Requirements:

Distance from IHX to process plant

Mitigating features

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Table 20.3.1-3 Comparison of Generation Plant and H2 Plant Design Duty Cycles

Number of Events Per Power Unit

Events

Generating HTGR Hydrogen Plant

HTGR

Start-up from cold conditions 240 240

Shutdown to cold conditions 240 240

Normal load following cycles(1)

22,000 Not Applicable

Frequency control 800,000 Not Applicable

Load reject to house load 100 [25]

Rapid load ramp 1500 up / 1500 down [500] down

Step load changes 3000(1)

[500] down

(1) Total number, up or down.

Functions that are unique to process heat applications include those related to control of radionuclides in the path to the process via the HTS, and the potential needed to mitigate the consequences of process related hazards on the nuclear heat source. In considering Table 20.3.1-3, it can be seen that the duty cycle for a representative process heat application, such as hydrogen production, is likely to be less demanding than a corresponding electric application, which is governed by electric grid requirements.

20.3.1.4 Screening Criteria

Taking into consideration the inputs of Section 20.3.1.1 through Section 20.3.1.3, screening criteria have been developed for the HTS selection process and are provided in Table 20.3.1-4.

The category of Readiness refers to the ability of the selected HTS to support NGNP objectives within the specified schedule which calls for startup within the 2016 to 2018 timeframe. In addition to the overt criterion relating to the ability to meet the NGNP timeline, which is highly weighted, two additional readiness criteria are identified. The first relates to R&D requirements and their associated costs and risk. Such R&D requirements can be thought of as an indirect measure of the likelihood of attaining NGNP goals in a timely manner. Also related is the ability of the vendor/supplier infrastructure to support NGNP requirements. To the extent that such infrastructure is not in place, or cannot be put in place in a timely manner, the risk to the NGNP objectives and schedule are increased. Since there is some overlap, the latter two criteria are given a medium weighting.

As stated in Section 20.3.1.2, the demonstration of commercial process heat applications is the principal mission of the NGNP. This is reflected in the high importance weighting of the

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Table 20.3.1-4 HTS Screening Criteria

Attribute Importance

Readiness

Ability to meet NGNP timeline (startup: 2016-2018) High

NGNP R&D Requirements/Cost/Risk Med

Vendor/Supplier Infrastructure Development Med

Support of Commercial Applications

Adequately demonstrates commercial process heat

applicationsHigh

NHS commonality with commercial products High

Can serve as process heat prototype for design certification High

Flexibility for demonstrating advanced applications Med

Flexibility for ultimate NGNP conversion to full-scale H2 production

Med

Performance

Ability to meet operational performance goals High

Overall Plant Efficiency Low

Operability Med

Availability Low

Cost

NGNP Capital Cost High

NGNP Operating Cost Low

first three criteria in this category. The third criterion, support of commercial process heat plant design certification, is viewed as particularly important.

In the category of Performance, the ability to meet operational performance goals (e.g., the provision of thermal energy to the process at required temperatures and thermal capacities with high reliability) is considered essential to the mission of the NGNP. Overall plant efficiency and availability are rated low, in recognition that compromises may be required to provide the flexibility for testing of multiple hydrogen production options, and that availability will be impacted by both testing requirements and equipment change out as different HPU options are tested. Operability is rated as medium in importance, recognizing that such operability will be optimized through experience gained with the NGNP.

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The capital cost of the NGNP is given a high weighting, recognizing that the difficulty of obtaining public and congressional support for the NGNP Project will increase with capital cost.Operating costs are given a low weighting, again anticipating the expected impacts of testing and equipment change out.

20.3.1.5 Power Conversion System Options

Power conversion system options were evaluated in a separate NGNP special study (20.4). As a result of this study, reference configurations were identified for the direct Brayton cycle, GTCC and Rankine cycle options.

The reference direct Brayton cycle is a single shaft recuperated and intercooled configuration, as shown in Figure 20.3.1-3. The reference GTCC incorporates a recuperated Brayton topping cycle with a single stage of compression and a bottoming Rankine cycle, as shown in Figure 20.3.1-4. A representative Rankine cycle was selected, as shown in Figure 20.3.1-5.

RHX

Precooler

Intercooler

PT ~GBLPC HPC

To Reactor

From Reactor

RHX

Precooler

Intercooler

PT ~GBLPC HPC

RHXRHX

Precooler

Intercooler

PT ~GBLPC HPC

Intercooler

PT ~GBLPC HPC PT ~GBLPC HPC

To Reactor

From Reactor

Figure 20.3.1-3 Reference Direct Brayton Cycle

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PT ~GBCOMP

SG

HPT IPT LPT ~

RHX

Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

To Reactor

From Reactor

PT ~GBCOMP

SG

HPT IPT LPT ~

RHX

Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

PT ~GBCOMP PT ~GBCOMP

SGSG

HPT IPT LPT ~

RHXRHX

Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

To Reactor

From Reactor

Figure 20.3.1-4 Reference GTCC

SG

HPT IPT LPT ~

Ble

ed

Flo

wB

lee

d F

low

Condenser

From Heat Source

To Heat Source

SG

HPT IPT LPT ~

Ble

ed

Flo

wB

lee

d F

low

CondenserSGSG

HPT IPT LPT ~

Ble

ed

Flo

wB

lee

d F

low

Condenser

From Heat Source

To Heat Source

Figure 20.3.1-5 Representative Rankine Cycle

20.3.1.6 H2 Production Unit Size

The range of sizes potentially required for the hydrogen production unit (HPU) was evaluated in a separate NGNP special study (20.6). As a result of that study, the minimum size that would allow scale up of the most critical components to commercial size for the applications evaluated was determined to be ~5 MWt. An alternate approach to HPU sizing would be demonstration of a single train of a commercial HPU. For this option, it was determined that approximately 50 MWt would be required. It is further noted that the thermal rating of the high temperature PCHX for the HyS process is approximately 200 MWt.

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20.3.1.7 References for Section 20.3.1

20.3.1-1 Lahoda, E.J., et.al., “Estimated Costs for the Improved HyS Flowsheet”, HTR2006, October 2006.

20.3.1-2 H2-MHR Conceptual Design Report: SI-Based Plant (GA-A25401), General Atomics, April 2006.

20.3.1-3 H2-MHR Conceptual Design Report: HTE-Based Plant (GA-A25402), General Atomics, April 2006.

20.3.1-4 “Technical Description of the PBMR Demonstration Power Plant”, Pebble Bed Modular Reactor Pty. Ltd Document 016956, Rev 4, February 14, 2006.

20.3.1-5 “High Temperature Gas-Cooled Reactors for the Production of Hydrogen: Establishment of the Quantified Technical Requirements for Hydrogen Production that will Support the Water-Splitting Processes at Very High Temperatures”, EPRI, Palo Alto, CA: 2004. 1009687.

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20.3.2 EVALUATION OF SHTS WORKING FLUID OPTIONS

The working fluid for the Primary Heat Transport System (PHTS) is defined to be the reactor helium coolant, which for the NGNP is helium. For the Secondary Heat Transport System (SHTS), there is an option to consider alternate heat transport fluids, each having advantages and disadvantages for the NGNP and corresponding commercial process heat plants.Specifically proposed have been carbon dioxide (CO2), which is used in British gas cooled reactors, liquid salts and liquid metals. Candidate SHTS fluids have been analyzed and compared as part of the overall NGNP Heat Transport System special study. A key difference among candidate fluids is a wide variation in volumetric heat capacity, and this significantly affects performance. A major design consideration is adequacy of obtainable and developed compatible materials. This concern raises issues of economics and of requirements for further development. Other design issues related to the fluid selection are operational (implications for duty cycle, availability, reliability & investment protection), component size and parasitic consumption of power for pumping.

20.3.2.1 Functions

PBMR PHP applications require transport of high temperature thermal energy from nuclear heat source to point of use. This reference separation distance is presently 100m for the study of PHP configurations with SMR [Ref. 20.3.2-1].

The functions of the Secondary Heat Transport System (SHTS) are the following:

Principal Functions

During operational modes in which the thermal energy produced in the nuclear

reactor is utilized in the process, transport thermal energy produced in the reactor

from the IHX to the Process Coupling Heat Exchanger (PCHX)

Contain the secondary fluid during all operational modes

Potential Function

For designated events within the duty cycle, transport reactor heat (reduced power

or decay heat) to an alternate heat sink, either in the Secondary Heat Transport

System (SHTS) or the process. [Note: The scope of this function is to be

determined.]

Ancillary Functions

Minimize energy losses (regenerative and to the environment)

Support personnel and investment protection goals

Support reliability and economic goals

Candidates

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NGNP_PCDR_20.3-HTS_R1_1-25-2007.doc January 25, 2007

40 of 150

Table 20.3.2-1 identifies the candidate Secondary Heat Transport System (SHTS) fluids and provides general comments on each.

Table 20.3.2-1 Candidate SHTS Coolants

Helium

NGNP primary coolant

Extensive experience base with HTGRs

Chemically inert

Highest conductivity of candidate gases Smaller heat exchangers

CO2

Experience base with Magnox/Advanced Gas Reactors to 650ºC (British)

Increased volumetric heat capacity Reduced pumping power vs. helium

Liquid Salt (LS)

Prior nuclear experience at high temperatures (to ~700ºC)

• Molten Salt Reactor Experiment/Molten Salt Breeder Reactor (MSRE/MSBR)

• Aircraft Reactor Experiment/Aircraft Reactor Test (ARE/ART)

Industrial experience, but with different compounds in baths vs. loops

Feasibility established

Temperature range of applicability bounded by melting/boiling points

Liquid Metal

No experience in temperature range of interest

Materials compatibility at high temperatures problematical per ORNL

Temperature range of applicability bounded by melting/boiling point

20.3.2.2 Initial Screening

As a first step in comparing Helium, CO2, Liquid Salt (LS) and Liquid Metal coolant options, the choice of liquid metal was eliminated from further consideration. There are possible liquid metal candidates having melting and boiling temperatures useable for coupling with high temperature process applications, these being

Lead

Bismuth

Lithium

Combinations of the above

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NGNP_PCDR_20.3-HTS_R1_1-25-2007.doc January 25, 2007

41 of 150

However, there is no experience with these liquid metals in the temperature range of interest, and ORNL input suggests that compatibility with materials at high temperatures is problematical. Above 600°C corrosion becomes a major issue [Ref. 20.3.2-2].

20.3.2.3 Thermophysical Properties

Table 20.3.2-2 provides relevant thermophysical properties of candidate SHTS working fluids. Of the candidate liquid salts, only three have been characterized to the extent that meaningful comparisons can be made. Two of these three well-characterized salts incorporate beryllium, which is both expensive and toxic. The two beryllium-based salts were developed for primary coolant applications, wherein nuclear properties are an important consideration. By contrast, FLiNaK, which was developed for SHTS applications, is relatively inexpensive and less toxic.

The thermophysical properties of greatest influence in the working fluid selection are the melting point, the volumetric heat capacity and the thermal conductivity. The melting point establishes the lower end of the feasible operating range for the liquid salts. The volumetric heat capacity is a measure of the energy carried in a given volume of fluid. This, in turn, is a key determinant of the required pipe size and the energy required for pumping. The thermal conductivity is a key factor in the sizing of heat exchangers.

In terms of gases, the principal thermophysical tradeoff between helium and CO2 relates to thermal conductivity on one hand and volumetric heat capacity on the other. The higher conductivity of helium implies smaller and less expensive heat exchangers, while the higher volumetric heat capacity of CO2 would be manifested in smaller pipes and reduced pumping power requirements. Relative to these gases, the high volumetric heat capacity and thermal conductivity of the liquid salts imply substantial advantages in terms of reduced heat exchanger and pipe sizes. The high volumetric heat capacity of liquid salts and the fact that they are incompressible fluids would result in low pumping power requirements compared to the gases.

20.3.2.4 Evaluation

Helium, CO2 and Liquid Salts (LS) were compared with respect to the following attributes and considerations. The details of these comparisons are provided in the subsections that follow.

Design Compatibility

Influence on Major Components Heat ExchangersCirculators/Pumps Piping and Insulation Valves and Seals

System Integration

System Operation

Availability and Reliability

Page 42: NGNP and Hydrogen Production Preconceptual Design Report Documents... · NGNP and Hydrogen Production Preconceptual Design Report NGNP-20-RPT-003 Special Study 20.3 – High Temperature

NG

NP

an

d H

yd

rog

en P

rod

uct

ion

Pre

con

cep

tual

Des

ign

Rep

ort

N

GN

P-2

0-R

PT

-00

3

Sp

ecia

l S

tud

y 2

0.3

– H

igh

Tem

per

atu

re P

roce

ss H

eat

Tra

nsf

er a

nd

Tra

nsp

ort

NG

NP

_P

CD

R_

20

.3-H

TS

_R

1_

1-2

5-2

00

7.d

oc

Jan

uar

y 2

5,

20

07

42 o

f 150

Tab

le 2

0.3

.2-2

H

eliu

m a

nd

Can

did

ate

Liq

uid

Salt

s

NIS

T d

ata

not

pro

vided a

bove

800C

0.0

35

(@

500C

)0.0

44

(@

800C

)

0.0

66

(avg

. 500

-800C

)

40.8

@7M

Pa

52.3

@9M

Pa

(avg

. 500

-800C

)

1190 (

@500C

)1

270 (

@800C

)

47.6

/61

.1 (

@50

0C

)34.0

/43

.5 (

@80

0C

)

NA

NA

CO

2

13 (

@500C

)1.7

(@

1000C

)23 (

@5

00C

)2.2

(@

1000C

)0.0

39 (

@5

00C

)0.0

55 (

@1

000C

),

(Pa·s

) x 1

03

Well

ch

ara

cte

rize

d;

Exp

en

siv

e;

To

xic

0.8

7

4270

2230

2010

(@700C

)

340

Na

F·B

eF

2(5

7 –

43)

ZrF

4fa

mily

recom

mende

d

for

consid

era

tion

by

OR

NL.

Indiv

idual

salts

inve

stig

ate

d

by

ON

RL.

Mix

ture

s n

ot

we

ll chara

cte

rize

d.

Melt r

ange is

estim

ate

for

vario

us

mix

ture

s.

380 -

410

KF

-ZrF

4&

Rb

F-Z

rF4

Well

cha

ract

eri

ze

d;

Use

d in

MS

RE

; E

xpe

nsiv

e,

To

xic

1

455

5

238

0

2036 (

@500C

)1

792 (

@1

000C

)

143

0

459

(LiF

) 2·B

eF

2

(FL

iBe

)

Well

cha

ract

eri

zed;

Re

fere

nce

fo

r M

SB

R s

econ

da

ry;

Ine

xpe

nsiv

e

Com

men

ts

4.5

0.3

68

(avg

. 500-1

000C

)k, W

/(m

·K)

3649

17.9

@7M

Pa

23.1

@9M

Pa

Cp, kJ/(

m3·K

)(a

vg.

500

-100

0C

)

1889

5200

Cp, J/(

kg

·K)

207

8 (

@500

C)

1785

(@

100

0C

)4.3

/5.5

(@

500C

)2.6

/3.4

(@

1000C

),

kg/m

3

(7M

Pa/9

MP

a)

Flu

robora

tes

recom

mended

for

co

nsid

era

tion

by

OR

NL.

NaF

-NaB

F4

was r

efe

rence

secondary

coo

lant fo

r M

SB

R

(700C

), b

ut

V.P

to

o h

igh >

700C

.

Mix

ture

s m

ay

be s

uitable

.

NA

Tboil,

C

TB

D455

NA

Tm

elt, C

Alk

ali

Flu

rob

ora

tes

(Mix

Req

’d)

NaF

-KF

-LiF

(11

.5-4

2-4

6.5

)

(FL

iNa

K)

He

liu

mP

rop

ert

y

NIS

T d

ata

not

pro

vided a

bove

800C

0.0

35

(@

500C

)0.0

44

(@

800C

)

0.0

66

(avg

. 500

-800C

)

40.8

@7M

Pa

52.3

@9M

Pa

(avg

. 500

-800C

)

1190 (

@500C

)1

270 (

@800C

)

47.6

/61

.1 (

@50

0C

)34.0

/43

.5 (

@80

0C

)

NA

NA

CO

2

13 (

@500C

)1.7

(@

1000C

)23 (

@5

00C

)2.2

(@

1000C

)0.0

39 (

@5

00C

)0.0

55 (

@1

000C

),

(Pa·s

) x 1

03

Well

ch

ara

cte

rize

d;

Exp

en

siv

e;

To

xic

0.8

7

4270

2230

2010

(@700C

)

340

Na

F·B

eF

2(5

7 –

43)

ZrF

4fa

mily

recom

mende

d

for

consid

era

tion

by

OR

NL.

Indiv

idual

salts

inve

stig

ate

d

by

ON

RL.

Mix

ture

s n

ot

we

ll chara

cte

rize

d.

Melt r

ange is

estim

ate

for

vario

us

mix

ture

s.

380 -

410

KF

-ZrF

4&

Rb

F-Z

rF4

Well

cha

ract

eri

ze

d;

Use

d in

MS

RE

; E

xpe

nsiv

e,

To

xic

1

455

5

238

0

2036 (

@500C

)1

792 (

@1

000C

)

143

0

459

(LiF

) 2·B

eF

2

(FL

iBe

)

Well

cha

ract

eri

zed;

Re

fere

nce

fo

r M

SB

R s

econ

da

ry;

Ine

xpe

nsiv

e

Com

men

ts

4.5

0.3

68

(avg

. 500-1

000C

)k, W

/(m

·K)

3649

17.9

@7M

Pa

23.1

@9M

Pa

Cp, kJ/(

m3·K

)(a

vg.

500

-100

0C

)

1889

5200

Cp, J/(

kg

·K)

207

8 (

@500

C)

1785

(@

100

0C

)4.3

/5.5

(@

500C

)2.6

/3.4

(@

1000C

),

kg/m

3

(7M

Pa/9

MP

a)

Flu

robora

tes

recom

mended

for

co

nsid

era

tion

by

OR

NL.

NaF

-NaB

F4

was r

efe

rence

secondary

coo

lant fo

r M

SB

R

(700C

), b

ut

V.P

to

o h

igh >

700C

.

Mix

ture

s m

ay

be s

uitable

.

NA

Tboil,

C

TB

D455

NA

Tm

elt, C

Alk

ali

Flu

rob

ora

tes

(Mix

Req

’d)

NaF

-KF

-LiF

(11

.5-4

2-4

6.5

)

(FL

iNa

K)

He

liu

mP

rop

ert

y

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NGNP_PCDR_20.3-HTS_R1_1-25-2007.doc January 25, 2007

43 of 150

Safety & Licensing

Economic Considerations

R&D

20.3.2.4.1 Design Compatibility

As suggested earlier, the relatively high melting point of candidate liquid salt working fluids represents a significant constraint on SHTS design options. As an example, the reference PBMR PHP configuration for hydrogen production via the HyS process is shown in Figure20.3.2-1. At a return temperature of 290ºC, this design would be incompatible with the use of liquid salt. Figure 20.3.2-2 depicts an alternate PBMR PHP coupling for the HyS process.While this latter coupling would be compatible with liquid salt SHTS working fluids, the high secondary return temperature would be problematical for helium or CO2 in terms of both pumping power and feasibility issues associated with the gas circulator. Further, integration of the hydrogen production unit and power conversion system for maximum efficiency would be more difficult with separation of the process heat and steam coupling.

20.3.2.4.2 Influence on Major Components

The selection of the SHTS working fluid has significant implications for major components of the heat transport system, including the IHX, PCHX and those components of the SHTS that are in contact with the working fluid. These implications are summarized as follows:

20.3.2.4.2.1 Heat Exchangers

In selecting the SHTS working fluid, there are a number of significant tradeoffs associated with both the IHX and process coupling heat exchanger (PCHX) (Table 20.3.2-3). In the case of helium or CO2, the SHTS must be operated at high-pressure to avoid excessive pumping energy requirements. With liquid salt (LS), the non-compressible nature of the fluid allows flexibility in selecting operating pressure and pressure differences can be staged between the primary loop and the process. However, this assumes that the pressure difference is within the design capability of the heat exchangers.

In the case of helium, a metallic IHX may be feasible, albeit marginal. It is not clear, however, whether a metallic IHX is feasible for CO2. A ceramic or carbon fiber reinforced carbon (CFRC) heat exchanger will almost certainly be required for LS, based on materials compatibility at the operating temperatures in question. A related issue is the transition between metal and ceramic in the manifold region of the heat exchanger.

Assuming that a suitable heat exchanger can be constructed, the very high heat temperature coefficient on the LS side would allow a lower reactor outlet temperature (ROT) for a given process temperature or, alternatively, an increased process temperature for a given ROT. For a given duty, a LS heat exchanger would tend to be smaller, and less expensive. A more subtle difference is illustrated by the inset figure of Table 20.3.2-3. Because the cross-section of the channels within the heat exchanger would be much smaller with liquid salt, the manifold section of the heat exchanger would be much smaller and the heat exchanger would operate more nearly in counter flow than the alternatives with gaseous SHTS working fluids. Another subtle

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NGNP_PCDR_20.3-HTS_R1_1-25-2007.doc January 25, 2007

44 of 150

PBMR IHX

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Fully Integrated PGS

SGSG

HPT LPT ~

Condenser

Preheater

Process Plant Battery Limits

950C

290C

9MPa

350C

900C

9MPa

500MWt

PBMR IHX

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Fully Integrated PGS

SGSG

HPT LPT ~

Condenser

Preheater

Process Plant Battery Limits

PBMR IHXIHX

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Fully Integrated PGS

SGSG

HPT LPT ~

Condenser

Preheater

Process Plant Battery Limits

950C

290C

9MPa

350C

900C

9MPa

500MWt

Figure 20.3.2-1 Reference PBMR PHP for H2 via HyS Process

Core

Inlet

Outlet

Blower / Pump

IHXProcessCouplingHXs

Process heat

Blower

IV

IV

PBMR PHP

Blower / Pump

SteamGenerator

Steam

IV

IV

PBMR PHP

950C

350C

900C

9MPa

674C, 9MPa

186MWt

314MWt

To PGS

724C

500MWt

Core

Inlet

Outlet

Blower / Pump

IHXProcessCouplingHXs

Process heat

Blower

IV

IV

PBMR PHP

Blower / Pump

SteamGenerator

Steam

IV

IV

PBMR PHP

950C

350C

900C

9MPa

674C, 9MPa

186MWt

314MWt

To PGS

724C

500MWt

Figure 20.3.2-2 Alternate HyS Process Coupling

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NG

NP

an

d H

yd

rog

en P

rod

uct

ion

Pre

con

cep

tual

Des

ign

Rep

ort

N

GN

P-2

0-R

PT

-00

3

Sp

ecia

l S

tud

y 2

0.3

– H

igh

Tem

per

atu

re P

roce

ss H

eat

Tra

nsf

er a

nd

Tra

nsp

ort

NG

NP

_P

CD

R_

20

.3-H

TS

_R

1_

1-2

5-2

00

7.d

oc

Jan

uar

y 2

5,

20

07

45 o

f 150

Tab

le 2

0.3

.2-3

H

eat

Exch

an

ger

s

Heliu

mC

O2

Liq

uid

Salt

H

igh

SH

TS

pre

ssure

re

qu

ire

d fo

r e

ffic

ien

t heat tr

ansport

C

onsis

ten

t w

ith IH

X p

ressure

ba

lan

cin

g

Im

plie

s h

igh d

P a

cro

ss P

CH

X

C

om

pa

rable

heat tr

ansport

chara

cte

ristic

s

on b

oth

sid

es o

f IH

X

C

om

patible

with s

hell

& tube P

CH

X

M

anifold

ing m

ore

difficult in c

om

pact H

Xs

(see inset figure

)

M

eta

llic H

Xs feasib

le, alb

eit

marg

inal

H

igh

SH

TS

pre

ssure

re

qu

ire

d fo

r e

ffic

ien

t heat tr

ansport

C

onsis

ten

t w

ith IH

X p

ressure

ba

lan

cin

g

Im

plie

s h

igh d

P a

cro

ss P

CH

X

S

econdary

heat tr

ansfe

r coeffic

ient w

ill

go

ve

rn H

X s

izin

g

H

X w

ill b

e larg

er,

more

expensiv

e

C

om

patible

with s

hell

& tube P

CH

X

M

anifold

ing m

ore

difficult in c

om

pact H

Xs

(see inset figure

)

M

eta

llic H

X feasib

ility

questionable

F

lexib

le o

pera

tin

g p

ressure

, e

sta

blis

hed b

y

co

ve

r ga

s

C

an

sta

ge

pre

ssu

re d

iffe

ren

ces

be

twee

n p

rim

ary

lo

op

and

pro

cess

P

ote

ntia

l to

op

era

te w

ith

low

er

LM

TD

R

edu

ce

RO

T fo

r g

ive

n p

roce

ss

tem

pera

ture

, or

A

llow

in

cre

ase

d p

rocess te

mp

era

ture

fo

r g

ive

n R

OT

M

ism

atc

h in

he

at tr

ansp

ort

ch

ara

cte

ristic

s

H

T c

oeffic

ient, v

olu

metr

ic h

eat capacity

mu

ch

hig

her

on

LS

sid

e

P

rim

ary

heat tr

ansfe

r coeffic

ient w

ill

go

ve

rn H

X s

izin

g

S

implif

ies m

anifold

ing in c

om

pact H

Xs

(see inset figure

)

F

low

are

a n

eeds to b

e m

uch s

malle

r on

LS

sid

e

F

ew

er,

sm

alle

r cha

nne

ls

C

oncern

with

plu

gg

ing

of sm

all

ch

an

ne

ls in

co

mp

act H

X d

esig

ns

Lik

ely

to r

equire c

era

mic

/CF

R H

Xs

M

eta

l to

cera

mic

/CF

RC

inte

rfaces a

n

issu

e

M

ay n

ot be c

om

patible

with tube &

shell

PC

HX

desig

ns

F

low

are

a o

uts

ide o

f tu

bes is

too larg

e

for

LS

W

ou

ld n

eed

ne

w P

CH

X d

esig

n

F

or

giv

en d

uty

, H

X w

ill b

e s

malle

r, m

uch

less e

xp

ensiv

e

Overa

ll:

Advanta

ge for

he

lium

/dis

advanta

ge for

CO

2/L

S w

ith a

vaila

ble

technolo

gy. F

utu

re a

dvanta

ge for

LS

with c

om

pact cera

mic

/CR

FC

HX

s

He

-to

-LS

He

-to

-He

He

liu

m-t

o-L

S I

HX

He

liu

m-t

o-H

eli

um

IH

X

He

-to

-LS

He

-to

-He

He

liu

m-t

o-L

S I

HX

He

liu

m-t

o-H

eli

um

IH

X

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NGNP and Hydrogen Production Preconceptual Design Report NGNP-20-RPT-003 Special Study 20.3 – High Temperature Process Heat Transfer and Transport

NGNP_PCDR_20.3-HTS_R1_1-25-2007.doc January 25, 2007

46 of 150

difference is that the volumetric flow of LS would be much smaller than that of the helium in the primary loop, and possibly the process fluid. In the case of the PCHX, it may be difficult to configure a shell and tube heat exchanger with LS on the outside of the tubes.

Overall, it is concluded that there is an advantage for helium and a modest disadvantage for CO2 with available technology. It is unlikely that heat exchangers can be constructed for a LS working fluid at the temperatures of the NGNP using present materials. When ceramic and/or CFRC heat exchangers become available, LS would have a significant advantage.

20.3.2.4.2.2 Circulators/Pumps

Trade-offs related to circulators and pumps are summarized in Table 20.3.2-4. Circulators have been developed for both helium and CO2 nuclear applications at temperatures up to approximately 350ºC. Above that level, incremental R&D would be required. CO2

pumping power requirements would be on the order of half those of helium for equivalent temperature and pressure, due to its higher volumetric heat capacity ( Cp). This is the principal incentive for its consideration. Pumping power requirements would be far less for LS, on the order of 1/5 that of helium [Ref. 20.3.2-3]. Such pumps have been demonstrated in prior applications, such as the Molten Salt Reactor Experiment (MSRE).

Overall, pumping energy requirements represent an advantage for CO2 vs. helium, and a large advantage for LS.

20.3.2.4.2.3 Piping and Insulation

Trade-offs related to piping and insulation are summarized in Table 20.3.2-5. Piping and insulation for helium applications are well-developed and have been demonstrated in several operating plants. For CO2 applications, piping and insulation have been applied at temperatures up to approximately 650ºC. With CO2, the piping is likely to be somewhat smaller than that with helium.

In concept, a LS working fluid would allow pipes to be reduced to approximately 1/5 of the size required for helium [Ref. 20.3.2-3]. In practice, however, there is no known practical wetted insulation system for LS, and this implies that the SHTS piping would have to operate at or near the LS temperature. At 900ºC, it is unlikely that metallic materials would be adequate and an alternative material, such as CFRC, would have to be selected.

Overall, the availability of established technology is a major advantage for helium, while reduced pipe -size would be a modest advantage for CO2. The lack of an internal insulation system is a feasibility issue for LS.

20.3.2.4.2.4 Valves and Seals

Trade-offs related to valves and seals are summarized in Table 20.3.2-6. In the case of both helium and CO2, SHTS valves would be both very large and would have to operate at high temperature. Experience shows that helium valves and seals are particularly difficult. In this respect, CO2 would have a modest advantage relative to helium.

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NG

NP

an

d H

yd

rog

en P

rod

uct

ion

Pre

con

cep

tual

Des

ign

Rep

ort

N

GN

P-2

0-R

PT

-00

3

Sp

ecia

l S

tud

y 2

0.3

– H

igh

Tem

per

atu

re P

roce

ss H

eat

Tra

nsf

er a

nd

Tra

nsp

ort

NG

NP

_P

CD

R_

20

.3-H

TS

_R

1_

1-2

5-2

00

7.d

oc

Jan

uar

y 2

5,

20

07

47 o

f 150

Ta

ble

20

.3.2

-4

Cir

cula

tors

/Pu

mp

s

Heliu

mC

O2

Liq

uid

Salt

H

ighe

st p

um

pin

g p

ow

er

R

&D

issue

s w

ith

te

mp

era

ture

s a

bo

ve

~

350

C

P

um

pin

g p

ow

er

low

er

than h

eliu

m, but

much g

reate

r th

an L

S

R

&D

issue

s w

ith

te

mp

era

ture

s a

bo

ve

~

350

C

P

um

pin

g p

ow

er

much

less th

an

fo

r g

ases

P

um

ps d

em

onstr

ate

d in e

arlie

r LS

a

pp

lica

tio

ns

Overa

ll:

Advanta

ge for

CO

2 v

s. heliu

m. L

arg

e a

dvanta

ge for

LS

Ta

ble

20

.3.2

-5

Pip

ing

an

d I

nsu

lati

on

Heliu

mC

O2

Liq

uid

Salt

In

tern

al in

sula

tion typic

ally

used to r

educe

pre

ssu

re b

oun

da

ry te

mpe

ratu

re, re

duce

energ

y losses

P

ote

ntia

l to

use

co

axia

l d

ucts

fo

r ho

t/co

ld

leg

s

P

ipin

g s

yste

ms d

em

onstr

ate

d, in

clu

din

g in

nu

cle

ar

ap

plic

atio

ns

S

imila

r syste

ms u

se

d in

PB

MR

DP

P

H

ow

ever,

inte

rnal coolin

g a

pplie

d in D

PP

w

ould

be m

ore

difficult in P

HP

and involv

e

incre

ase

d e

ne

rgy lo

sses

A

s w

ith h

eliu

m e

xcept th

at pip

ing a

nd

va

lve

s m

ay b

e s

om

ew

ha

t sm

alle

r

Pip

e s

ize ~

1/5

that of H

e p

ipe

N

o k

now

n p

ractical LS

wetted insula

tion

syste

m

Im

plie

s p

ressu

re b

ou

nda

ry m

ust

opera

te a

t or

near

LS

tem

pera

ture

E

limin

ate

s o

r m

akes m

ore

difficult

pote

ntial fo

r coaxia

l heat tr

ansport

S

ug

gests

CF

RC

pre

ssu

re b

ou

nd

ary

M

eta

llic m

ate

rials

ma

y n

ot be a

dequate

at 900ºC

E

xte

rnal in

sula

tion w

ill b

e r

equired to

red

uce

en

erg

y lo

sses

Overa

ll:

Esta

blis

hed technolo

gy a

majo

r advanta

ge for

he

lium

, re

duced p

ipe s

ize a

modest advanta

ge for

CO

2. L

ack o

f in

tern

al in

sula

tion

syste

m a

feasib

ility

issue for

LS

.

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NG

NP

an

d H

yd

rog

en P

rod

uct

ion

Pre

con

cep

tual

Des

ign

Rep

ort

N

GN

P-2

0-R

PT

-00

3

Sp

ecia

l S

tud

y 2

0.3

– H

igh

Tem

per

atu

re P

roce

ss H

eat

Tra

nsf

er a

nd

Tra

nsp

ort

NG

NP

_P

CD

R_

20

.3-H

TS

_R

1_

1-2

5-2

00

7.d

oc

Jan

uar

y 2

5,

20

07

48 o

f 150

Ta

ble

20

.3.2

-6

Va

lves

& S

eals

Heliu

mC

O2

Liq

uid

Salt

V

ery

larg

e v

alv

es r

equired

S

ize a

nd p

ote

ntial fo

r le

akage

pro

ble

matic

al f

or

SH

TS

isola

tion v

alv

es,

if r

equired

Leak-t

ight seals

difficult

W

eld

ed s

eals

typic

al fo

r pre

ssure

b

ou

nd

ary

N

on-w

eld

ed

se

als

ha

ve

bee

n

de

mo

nstr

ate

d fo

r in

tern

al c

om

po

ne

nts

L

arg

e v

alv

es r

eq

uired

S

ize a

nd p

ote

ntial fo

r le

akage

pro

ble

matic

al f

or

SH

TS

isola

tion v

alv

es,

if r

equired

P

ipe

dia

me

ters

ma

y b

e r

edu

ced

re

lative

to

heliu

m

Leak-t

ight seals

less d

ifficult than w

ith

heliu

m

S

ma

ll va

lve

s r

eq

uired

M

echanic

al clo

sure

valv

es h

ave n

ot yet

be

en

de

ve

lope

d

In

early a

pplic

ations, LS

tended to

cle

an s

urf

ace to c

onditio

n that

pro

mo

ted

se

lf-w

eld

ing

F

reeze

va

lves w

ere

use

d in

so

me

ea

rly

applic

ations; effective, but slo

w

N

ew

er

ma

terial altern

atives m

ake

feasib

ility

lik

ely

; how

ever

qualif

ication

req

uired

to

90

0ºC

N

o m

ech

an

ica

l se

als

use

d in

pri

or

desig

ns

N

ew

er

ma

terial altern

atives m

ake

feasib

ility

lik

ely

; how

ever

qualif

ication

req

uired

to

90

0ºC

Overa

ll:

Sig

nific

ant R

&D

issue for

heliu

m/C

O2 If S

HT

S isola

tion v

alv

es r

equired. L

S w

ould

require m

uch s

malle

r valv

es/s

eals

.

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NGNP and Hydrogen Production Preconceptual Design Report NGNP-20-RPT-003 Special Study 20.3 – High Temperature Process Heat Transfer and Transport

NGNP_PCDR_20.3-HTS_R1_1-25-2007.doc January 25, 2007

49 of 150

LS valves and seals would be significantly smaller than their gas working fluid counterparts. Regulating valves have been previously demonstrated in MSRE and other experiments. However, at 900ºC, the maximum temperature of the NGNP SHTS is significantly higher than in these earlier applications.

At this time, it is not clear that SHTS isolation valves would be required for the NGNP.If required, such valves would represent a significant R&D issue for helium or CO2.

20.3.2.4.3 System Integration

Trade-offs related to system integration are summarized in Table 20.3.2-7. As previously noted, the freezing point of liquid salts places constraints on SHTS design options. However, the use of LS, in conjunction with ceramic/CFRC or other heat exchangers which are not limited by creep effects, would allow staging of the pressure from the primary loop to the process. For efficient heat transport, both helium and CO2 would need to operate at relatively high-pressure, and most of the pressure drop would have to be taken across the PCHX.

Helium provides the most flexibility with respect to biasing the differential pressure across the IHX. In the case of both CO2 and LS, the IHX pressure differential must be biased toward the SHTS. In the case of the PCHX, it is not clear as to which direction the pressure differential would be biased. There are potentially significant consequences of leakage in either direction.

Overall, helium provides the most flexibility for system integration with available technology. Leakage bias and the consequences of leaks are a disadvantage for CO2 and a feasibility issue for LS.

20.3.2.4.4 System Operation

Trade-offs related to system operation are summarized in Table 20.3.2-8. There is significant operational experience with helium in earlier HTGRs. There is also significant experience with CO2 in British gas-cooled reactors, albeit at lower temperatures. The selection of LS as the SHTS working fluid poses significant operational issues. The LS must be heated to a liquid state prior to introduction to the SHTS during startup. Separate provisions will be required to preheat the SHTS components in contact with the LS, in order to avoid thermal shock. For any event in which the temperature of the LS would drop below the freezing point, provisions must be made to drain the LS from all SHTS components.

Overall, operational experience at high temperature is an advantage for helium. The freezing of LS implies significant operational issues with startup, shut down and response to certain transients.

20.3.2.4.5 Availability and Reliability

Trade-offs related to availability and reliability are summarized in Table 20.3.2-9. The consequences of leaks in either the IHX or PCHX are a distinguishing characteristic. With

Page 50: NGNP and Hydrogen Production Preconceptual Design Report Documents... · NGNP and Hydrogen Production Preconceptual Design Report NGNP-20-RPT-003 Special Study 20.3 – High Temperature

NG

NP

an

d H

yd

rog

en P

rod

uct

ion

Pre

con

cep

tual

Des

ign

Rep

ort

N

GN

P-2

0-R

PT

-00

3

Sp

ecia

l S

tud

y 2

0.3

– H

igh

Tem

per

atu

re P

roce

ss H

eat

Tra

nsf

er a

nd

Tra

nsp

ort

NG

NP

_P

CD

R_

20

.3-H

TS

_R

1_

1-2

5-2

00

7.d

oc

Jan

uar

y 2

5,

20

07

50 o

f 150

Tab

le 2

0.3

.2-7

S

yst

em I

nte

gra

tion

Heliu

mC

O2

Liq

uid

Salt

P

ressure

diffe

rential fr

om

prim

ary

to

pro

cess m

ust la

rge

ly b

e take

n a

cro

ss

PC

HX

Leakage b

iases:

M

ore

fle

xib

le for

IHX

P

CH

X b

iased tow

ard

pro

cess

P

ressure

diffe

rential fr

om

prim

ary

to

pro

cess m

ust la

rge

ly b

e take

n a

cro

ss

PC

HX

Leakage b

iases:

IH

X m

ust be b

iased tow

ard

SH

TS

P

CH

X b

iased tow

ard

pro

cess

F

lexib

ility

to s

tage p

rim

ary

to p

rocess

pre

ssure

diffe

rential

Leakage b

iases:

IH

X leakage m

ust be b

iased tow

ard

LS

sid

e o

f IH

X

P

CH

X le

akage b

ias:

If tow

ard

LS

sid

e, need to e

valu

ate

co

nseq

uen

ces o

f p

rocess g

as

ing

ress

If tow

ard

LS

sid

e, im

plie

s h

igh d

P

acro

ss IH

X

If tow

ard

pro

cess s

ide, m

ust assess

co

nseq

uen

ces o

f sa

lt c

on

tam

ina

tio

n

Overa

ll:

Le

aka

ge

bia

s a

nd

co

nseq

uences a

dis

ad

van

tag

e fo

r C

O2; fe

asib

ility

issue for

LS

.

Page 51: NGNP and Hydrogen Production Preconceptual Design Report Documents... · NGNP and Hydrogen Production Preconceptual Design Report NGNP-20-RPT-003 Special Study 20.3 – High Temperature

NG

NP

an

d H

yd

rog

en P

rod

uct

ion

Pre

con

cep

tual

Des

ign

Rep

ort

N

GN

P-2

0-R

PT

-00

3

Sp

ecia

l S

tud

y 2

0.3

– H

igh

Tem

per

atu

re P

roce

ss H

eat

Tra

nsf

er a

nd

Tra

nsp

ort

NG

NP

_P

CD

R_

20

.3-H

TS

_R

1_

1-2

5-2

00

7.d

oc

Jan

uar

y 2

5,

20

07

51 o

f 150

Ta

ble

20

.3.2

-8

Sy

stem

Op

era

tio

n

Heliu

mC

O2

Liq

uid

Salt

S

ign

ific

an

t o

pe

ratio

na

l e

xpe

rie

nce

with

h

eliu

m h

ea

t tr

an

sp

ort

; n

o m

ajo

r is

sue

s

S

ign

ific

an

t o

pe

ratio

na

l e

xpe

rie

nce

with

C

O2 h

eat tr

ansport

at lo

wer

tem

pera

ture

s;

no

ma

jor

issue

s

S

tart

up/S

hutd

ow

n

S

alt m

ust be h

eate

d to liq

uid

sta

te a

nd

intr

oduced to S

HT

S a

s p

art

of sta

rtup

LS

must be d

rain

ed for

cold

shutd

ow

n

T

em

pera

ture

mu

st b

e m

ain

tain

ed

above m

inim

um

level fo

r hot sta

ndby

A

lte

rna

te h

eat so

urc

e r

eq

uire

d fo

r a

bo

ve

S

teady S

tate

/Tra

nsie

nts

N

o u

nu

su

al is

su

es a

ntic

ipa

ted

with

ste

ady s

tate

opera

tion

T

ransie

nts

resu

ltin

g in

sh

utd

ow

n

ad

dre

ssed

abo

ve

Overa

ll:

Fre

ezin

g o

f LS

im

plie

s s

ignific

an

t opera

tional i

ssues w

ith s

tart

up, shutd

ow

n a

nd r

esponse to c

ert

ain

tra

nsie

nts

. O

pera

tional exp

eri

ence

w

ith h

eliu

m a

t hig

h tem

pera

ture

s a

n a

dvanta

ge.

Tab

le 2

0.3

.2-9

A

vail

ab

ilit

y/R

elia

bil

ity

Heliu

mC

O2

Liq

uid

Salt

C

ontinued o

pera

tion w

ith s

mall

HX

leaks

ma

y b

e p

ossib

le

D

ifficu

lty in

lo

ca

tin

g/r

ep

airin

g le

aks a

pro

ble

m w

ith c

om

pact H

Xs

M

ust be s

hut dow

n w

hen a

ny leak is

dete

cte

d

D

ifficu

lty in

lo

ca

tin

g/r

ep

airin

g le

aks a

pro

ble

m w

ith c

om

pact H

Xs

M

ust be s

hut dow

n w

hen a

ny leak is

dete

cte

d

D

ifficu

lty in

lo

ca

tin

g/r

ep

airin

g le

aks a

pro

ble

m w

ith c

om

pact H

Xs

Ove

rall: C

on

se

qu

ences o

f le

aks a

dis

adva

nta

ge

of C

O2, m

ajo

r dis

advanta

ge o

f LS

.

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NGNP and Hydrogen Production Preconceptual Design Report NGNP-20-RPT-003 Special Study 20.3 – High Temperature Process Heat Transfer and Transport

NGNP_PCDR_20.3-HTS_R1_1-25-2007.doc January 25, 2007

52 of 150

helium, continued operation may be possible with small leaks that are within technical specification limits. With CO2 or LS, the plant must be shut down for repairs upon detection of any leaks.

Overall, the consequences of leaks represent a disadvantage for CO2, and a major disadvantage for LS.

20.3.2.4.6 Safety & Licensing

Trade-offs related to safety and licensing are summarized in Table 20.3.2-10. As with availability and reliability, the consequences of leaks are a distinguishing characteristic among the candidate working fluids. An advantage of LS is the flexibility to move the process to a greater distance from the reactor.

20.3.2.4.7 Economic Considerations

Trade-offs related to economic considerations are summarized in Table 20.3.2-11. Relative to helium, it is not clear whether the reduced pumping energy requirements potentially obtained with CO2 offset the larger and more expensive heat exchangers that would be required.With LS, the IHX, PCHX and other main SHTS components would tend to be smaller and less expensive. These reductions would be offset by additional auxiliary systems required for LS melting, injection, withdrawal and temperature control. Overall there may be a capital cost advantage for LS, and such advantage would increase with the distance between the IHX and PCHX. Operating costs may be higher or lower for LS, with key tradeoffs being associated with lower pumping energy vs. higher maintenance costs.

20.3.2.4.8 R&D Requirements

Trade-offs related to R&D requirements are summarized in Table 20.3.2-12. Of the SHTS working fluid options, helium would require the least R&D support. Incremental R&D for CO2 largely relates to materials compatibility at the high temperatures of the NGNP. In particular, the feasibility of a metallic IHX needs to be verified. With LS, an advanced material will almost certainly be required for the IHX. For any of the options incorporating ceramic/CFRC heat exchangers, R&D would be required to develop the ceramic to metal transitions at the interfaces between the heat exchangers and the ducts.

As earlier noted, piping and insulation is a key LS issue that would have to be resolved through R&D. Overall, R&D requirements for CO2 would be somewhat greater than for helium if metallic heat exchangers are feasible. The application of LS would require several major R&D initiatives.

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NG

NP

an

d H

yd

rog

en P

rod

uct

ion

Pre

con

cep

tual

Des

ign

Rep

ort

N

GN

P-2

0-R

PT

-00

3

Sp

ecia

l S

tud

y 2

0.3

– H

igh

Tem

per

atu

re P

roce

ss H

eat

Tra

nsf

er a

nd

Tra

nsp

ort

NG

NP

_P

CD

R_

20

.3-H

TS

_R

1_

1-2

5-2

00

7.d

oc

Jan

uar

y 2

5,

20

07

53 o

f 150

Tab

le 2

0.3

.2-1

0

Safe

ty/L

icen

sin

g

Heliu

mC

O2

Liq

uid

Salt

R

equires p

rocess to b

e c

lose to r

eacto

r

Re

quires p

rocess to b

e c

lose to r

eacto

r

C

onseq

ue

nce

s o

f C

O2 ingre

ss into

prim

ary

lo

op m

ay h

ave

to b

e a

ddre

ssed

F

lexib

ility

for

movin

g p

rocess fart

her

from

re

acto

r

C

onsequences o

f salt ingre

ss into

prim

ary

lo

op m

ay h

ave

to b

e a

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adeoffs u

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.

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NG

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Tab

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R&

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re feasib

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equires m

ajo

r R

&D

initia

tive.

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Table 20.3.2-13 Summary of SHTS Working Fluid Evaluation Results

Item Helium CO2 LS

Design Compatibility + - - -

Influence on Major Components

Heat Exchangers + - +/-

Circulators/Pumps - + ++

Piping and Insulation ++ + - -

Valves and Seals - - - +

System Integration + - - -

System Operation + - - -

Availability and Reliability + - - -

Safety & Licensing +/- - +/-

Economic Considerations +/- +/- +

R&D + - - -

20.3.2.5 Evaluation and Recommendation

A qualitative summary of the SHTS working fluid evaluation results is provided in Table 20.3.2-13. The most significant factors and bases for a tradeoff decision are summarized as follows:

LS has a much higher volumetric heat capacity ( •CP) than helium or CO2, and this

implies reduced piping diameters and lower SHTS pumping power requirements, on the

order of 1/5th that for helium. The volumetric heat capacity of CO2 is about twice that of

helium, with a corresponding reduction in pumping power requirements at equivalent

temperatures and pressures.

LS has a much higher thermal conductivity than helium or CO2, which translates to

higher heat transfer coefficients and reduced log-mean temperature difference (LMTD)

requirements that can be taken advantage of in terms of either lower reactor outlet

temperature for a given process temperature or higher process temperatures for increased

efficiency and smaller heat exchangers. The thermal conductivity of CO2 is only about

1/6 that of helium, implying significantly larger and more expensive heat exchangers

with CO2.

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Experience with CO2 and LS heat transport fluids has not extended to the temperature

range of the NGNP SHTS.

There is a requirement for an alternate heat source of undetermined size for startup of a

LS heat transport circuit, and to avoid freeze-up there needs to be a drain, storage and

vent system for LS.

The LS heat transport pressure-retaining pipes will have to operate at LS temperatures,

unless an internal insulating system can be devised - this implies a new piping material.

Therefore, insulation to limit heat loss will be external to the pipe. On the other hand,

heat losses will be reduced with LS, due to the smaller required pipe sizes. With helium

or CO2, internal insulation is possible and the pipe can run nearer to external ambient

temperature. Helium and CO2 working fluids are compatible with an optional

configuration of coaxial Secondary Heat Transport System (SHTS) transport pipes.

LS is not compatible with conventional shell and tube PCHXs that have the process fluid

and catalyst on the inside of the tubes. For a given heat delivery, the flow rate on the LS

side would be much smaller than that on the process side, leading to issues with shell side

flow distribution. With compact heat exchangers, there is a lower limit to the size of flow

passages, below which plugging can be a concern, and this limit is more likely

encountered in the smaller passages of HXs with LS.

With LS as the SHTS working fluid, any detectible leak in the IHX or PCHX will require

immediate shut-down for repairs, while continued operation is feasible with small leaks

in the IHX of an all-helium heat transport system. With CO2, leaks would also require

immediate shutdown for repair; however, the consequences of leaks are unlikely to be as

severe as those with LS.

R&D will be required for any of the three SHTS working fluid candidates. Of the three,

helium has the fewest R&D requirements. Assuming that metallic heat exchangers are

determined to be feasible, CO2 would have modest incremental R&D needs relative to

helium. The LS alternative will almost certainly require a ceramic/CFRC IHX, and has

unique R&D needs in the areas of piping materials compatibility, piping insulation

design, high-temperature pumps and pump and valve seals. LS R&D requirements are

not compatible with the present schedule for the NGNP.

The conclusion of this evaluation is that helium should be selected as the SHTS working fluid for the NGNP and that the PCHX should be located as close to the IHX as possible. There should be continued following of LS heat transport system development with a view to future distributed process heat applications (e.g., energy parks), where longer distance high-temperature process energy transport is mandatory. As noted in Section 20.3.1.2.2, a differentiating requirement of the NGNP is to provide flexibility for demonstrating various energy utilization options. If future demonstration of LS thermal energy transport in the NGNP environment is desired, an option is to replace the PCHX with a secondary IHX and to add a tertiary LS loop to transport energy to a more distant location.

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20.3.2.6 References for Section 20.3.2

20.3.2-1 Smith, C., Beck, S. and Galyean, B., “An Engineering Analysis for Separation Requirements of a Hydrogen Production Plant and High-Temperature Nuclear Reactor”, INL/EXT-05-00137 Rev 0, INL, March 2005.

20.3.2-2 “Liquid Salt for Secondary Heat Transport Applications”, Record of Meeting at ORNL, November 8, 2005 Technology Insights, 21 Nov 2005.

20.3.2-3 du Toit, B. and van Ravenswaay, J., “The Impact of Separation Distance between Reactor and Process on the Choice of Secondary Heat Transport Coolant for High Temperature Process Heat Applications” (I00000153), Proceedings HTR2006, Johannesburg, South Africa, October 1-4, 2006.

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20.3.3 IHX READINESS ASSESSMENT

20.3.3.1 Introduction

The NGNP reference concepts are helium-cooled, graphite-moderated, thermal neutron spectrum reactors with a design goal outlet helium temperature of 950°C (see Section 20.3.3.4, Assessment Input Requirements). The NGNP is expected to produce both electricity and hydrogen. Depending upon the selected Heat Transport System architecture, the thermal energy for hydrogen production and, potentially, electrical production will be transferred by an intermediate heat exchanger (IHX).

The basic technology for the NGNP was established in earlier high temperature gas-cooled reactor (HTGR) demonstration plants (DRAGON, Peach Bottom, AVR, Fort St. Vrain, and THTR). Presently, a prototype commercial HTGR for electricity generation, the Pebble Bed Modular Reactor (PBMR) Demonstration Power Plant (DPP), is being deployed in South Africa. Furthermore, the Japanese High Temperature Test Reactor (HTTR) and Chinese HTR-10 test reactors are demonstrating the feasibility of some of the planned components and materials.

The proposed high operating temperatures in the NGNP place significant constraints on the choice of materials selected for the IHX. The main focus of this section is the materials readiness issues associated with the IHX.

20.3.3.1.1 Purpose

The purpose of this section is to document the results of an IHX materials assessment performed to support a pre-conceptual design study for the NGNP. This assessment includes an evaluation of IHX design issues, potential metallic and ceramic IHX fabrication materials, applicable codes and standards, Design Data Needs (DDNs) and associated R&D implications for the NGNP and, finally, appropriate conclusions and recommendations.

20.3.3.1.2 Scope

The scope of this assessment includes evaluation of the following issues associated with the IHX:

The likelihood of achieving a He/He IHX design with an inlet temperature up to 950ºC for procurement by 2012, using available mature metallic alloys at high operating capacity factor (>95%)

Projected lifetimes under various conditions

IHX designs (tube and shell vs. compact)

The pros and cons regarding application to the NGNP

The candidate metallic materials for the IHX with respect to applicability and adequacy for the proposed service

Significant gaps in the knowledge base for the application of these materials

The availability and/or applicability of codes and standards that could be used for IHX materials procurement, design, fabrication and testing

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Significant gaps in materials property databases, design methods and codes and standards

An approach to resolution where codes and standards are found to be unavailable or inadequate (identified in terms of DDNs)

Required R&D programs to address gaps and needs

The design options for routing reactor thermal energy to the IHX

Alternate IHX materials (e.g., composites, ceramics) and associated pros and cons

Implications for the NGNP pre-conceptual design

Conclusions and recommendations

20.3.3.1.3 Outline

The outline for the remainder of this assessment is as follows:

ITRG Recommendations

Definition of “High Temperature” for Metallic Materials

Assessment Input Requirements

IHX Design Considerations

Metallic Materials Assessment

Ceramic Materials Assessment

Codes and Standards Readiness

Design Data Needs and R&D

Implications for NGNP Preconceptual Design

Final Conclusions and Recommendations

References

20.3.3.2 Independent Technology Review Group Recommendations Associated with the IHX

The Independent Technology Review Group (ITRG) performed their review from November 2003 through April 2004. The purpose of the ITRG review was to provide a critical review of the proposed NGNP project and identify areas of R&D that needed attention. As stated in the report, the ITRG observations and recommendations focus on overall design features and important technology uncertainties of a very-high-temperature nuclear system concept for the NGNP.

The ITRG report entitled Design Features and Technology Uncertainties for the Next

Generation Nuclear Plant was issued on June 30, 2004 by the INL [Ref. 20.3.3-1]. An analysis of the materials-related risk issues noted in this report and comments associated with these risk issues are given below. The NGNP Program response was originally stated in Revision 3 of the NGNP Materials Program Plan, Section 20.3.1.4 [Ref. 20.3.3-2].

20.3.3.2.1 Upper Temperature Limit

Technical Observation: The originally specified NGNP gas outlet temperature of 1000°C is beyond the current capability of metallic materials. The requirement of a gas outlet temperature

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of 1000°C will result in operating temperatures for metallic core components (core barrel, upper shroud, control rod drive assemblies), and IHX components that will approach 1200°C in some cases. Metallic materials that are capable of withstanding this temperature for the anticipated plant life will not be available on the NGNP schedule, if they can be developed at all.Nonmetallic materials capable of this temperature will require a development program that cannot support the NGNP schedule.

Associated Risk: The requirement for a gas outlet temperature of 1000°C represents a significant risk that ITRG judges cannot be resolved consistent with the schedule for the NGNP.

Recommendation: It is recommended that the required gas outlet temperature be reduced such that metallic components are not exposed to more than 900°C for the base NGNP design. Raising the gas outlet temperature to 950°C may be considered but at the potential expense of a reduced life (<60 year) for key components (e.g., the IHX).

NGNP Materials Program Response: This recommendation was implemented and the NGNP materials program now focuses on a reactor outlet temperature for the NGNP of 950°C maximum.

20.3.3.2.2 Pressure Boundary Time-Dependent Deformation

Technical Observation: Several of the NGNP concepts that were reviewed require many of the irreplaceable Class I boundary components (pressure vessel, piping, etc.) to operate at temperature and stress combinations that will result in significant time-dependent deformation (creep) during the component life. While there is allowance (ASME Code Case) for the inclusion of time-dependent deformation in pressure vessel designs, this has not been a part of commercial nuclear pressure vessel and piping systems in the past and represents a very significant departure from current practice. Moreover, it is likely that creep as well as fatigue-related time-dependent deformation will be present. Creep-fatigue interaction represents the most complex form of high temperature behavior, often requiring component-specific design rules. In addition, the regulatory infrastructure does not have experience with including significant time-dependent deformation in the licensing and safety evaluation process.

Associated Risk: The allowance of time-dependent deformation in the non-replaceable Class I boundary represents an unacceptable risk for the NGNP program.

Recommendation: The ITRG recommends that time-dependent deformation be limited to “insignificant,” as defined by the ASME Code, during the life of non-replaceable (60-year life) components for the NGNP. Time-dependent deformation for replaceable Class I components (portions of the IHX, interface heat exchanger for the hydrogen system, etc.) can be allowed, but only with the addition of significant additional levels of inspection and monitoring. However, the fraction of the Class I boundary that experiences significant creep deformation must be limited as much as possible.

NGNP Materials Program Response: The program agrees with this recommendation and this philosophy is currently reflected in materials design approaches.

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20.3.3.2.3 ASME Codes and Standards

Technical Observation: Several of the NGNP concepts require either that existing materials be qualified for Section III service or that entirely new materials be developed. In addition, some of the NGNP designs allow for creep deformation in the Class I boundary.

Associated Risk: The risk is associated with the time that will be necessary for the qualification of existing or new materials for use in the Class I boundary. In addition, there will be risk associated with the allowance of creep deformation as a part of the Class I boundary design, both technical and regulatory. It is the judgment of the ITRG that the development and qualification of new materials for Section III, Class I service cannot be achieved in the time frame for the NGNP. Further, it is our judgment that the qualification of existing materials for Class I service where creep deformation is allowed represents an unacceptable risk for the program.

Recommendation: The ITRG recommends that the NGNP non-replaceable Class I boundary components be constructed using materials that are currently qualified for Class I service or that can be qualified without an appreciable data gathering program. The ITRG further recommends that qualification of new materials be limited to those that are either currently listed in Section II for Section VIII service or for which a database currently exists.

NGNP Materials Program Response: The materials development program agrees with these recommendations assuming that an aggressive schedule for plant construction is an overriding consideration; however, as noted in the discussion above, the use of SA-508/533 LWR RPV steel for the NGNP RPV will cause limitations on the design of the plant which will need to be addressed. The other important issue involves a Nuclear Energy Research Advisory Committee (NERAC) recommendation to design a prototype VHTR plant with lesser initial capabilities but with the ability to upgrade the capabilities of the plant over time. This could be more easily accomplished if the Class I boundaries were fabricated with a more advanced alloy because the Class I boundary components are not easily replaceable and the materials used for these components establish long term limitations on possible higher power, higher temperature plant operation that may represent a desirable modification in the future. While the higher alloy content steel 9Cr- 1MoV is included in ASME Section III, Subsection NH for Class I service, it is not necessarily adequately qualified for the full ranges of time and temperature of service that the plants may require. It may be possible to address these issues with design changes over time but this approach represents a tradeoff of reduced initial risk versus potential additional long term risk associated with possible long term plant upgrades.

20.3.3.2.4 Corrosion and Oxidation

Technical Observation: High-temperature operation of metallic components for times up to 60 years will result in the possibility of corrosion damage. This damage will most likely be associated with coolant contamination within the primary system or air oxidation on external surfaces. In addition, the development of oxidized surfaces may affect the overall thermal resistance of the system as a result of changes in emissivity.

Associated Risk: The risk is associated with potential changes in material properties as a result of corrosion-induced embrittlement.

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Recommendation: This risk is judged to be minimal, assuming that adequate coolant contaminant control is exercised.

NGNP Materials Program Response: The materials development program does not consider this risk to be minimal because it is currently unclear how effective coolant contamination control measures will be. Therefore, the program is planning to perform adequate testing to characterize changes that take place from corrosion induced embrittlement. However, it is now clear, based on a subsequent literature review, that this issue has not been a significant problem with VHTR plants that have operated in the past. These plants may not be representative of the NGNP design; however, the results noted from the review are encouraging. The program also believes that continued R&D in this area will be useful during licensing discussions with the NRC if questions arise concerning this issue. The new issue of particular concern for NGNP is the impact of impure helium corrosion on the very thin sections that may be required within compact heat exchangers, if they are used to minimize system cost.

20.3.3.2.5 Microstructural Stability

Technical Observation: The exposure of metallic materials to high temperature for long periods of time may result in microstructural changes in pressure boundary materials that result in a degradation of material properties.

Associated Risk: The risk is associated with embrittlement of materials. However, with an adequate monitoring and inspection program, this risk is judged to be acceptable.

Recommendation: The ITRG recommends that the development program conducted for the NGNP include tests to identify thermal aging issues. Special consideration should be given to welds and heat-affected zones.

NGNP Materials Program Response: The materials development program agrees with this recommendation and investigation of these issues have been integrated into the program.

20.3.3.2.6 Advanced Materials Development

Technical Observation: Operation at a gas outlet temperature of 1000°C will require use of nonmetallic materials in core structural applications and will require development of new materials for heat exchanger designs.

Associated Risk: The risk is associated with the time it will take for the development and qualification of new materials. It is judged that sufficient new material development and qualification cannot be achieved in time to support the NGNP construction permit application (2009).

Recommendation: The ITRG recommends that NGNP materials be limited to those currently qualified or that can be qualified with minimal effort. As discussed in earlier sections, this will require that the gas outlet temperature be reduced.

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NGNP Materials Program Response: The materials development program agrees with this recommendation. This is the reason that the program has selected only the most mature high temperature metallic alloys, RPV materials, and non-metallic materials for qualification within the NGNP. No inherently new materials are being developed, though small variations to existing materials are being evaluated, including graphites from currently available coke sources, controlled chemistry variations of high temperature alloys, like Alloy 617, and minor architecture and processing variations of C-C composite already developed for other applications.

20.3.3.2.7 Summary Observations Regarding ITRG Report

The recommendations and discussion noted above have the following implications with regard to the IHX:

The reactor outlet temperature for the NGNP should not exceed 950ºC, based in part on IHX materials considerations.

Non-replaceable metallic components designed for the full plant lifetime (60 years) should be limited to ~900ºC. Metallic components operating at temperatures higher than ~900ºC, notably including high-temperature sections of the IHX, are likely to have reduced lifetimes and should be designed for replacement.2

Time-dependent deformation for Class 1 pressure boundary components should be “insignificant”, as defined by the ASME Code.

The IHX should be designed to minimize stresses imposed on the metallic alloy due to the low margin of allowable creep stress associated with available metallic alloys operating in the 900-950ºC temperature range.

Metallic materials should be limited to alloys listed in ASME Section II for Section III or Section VIII service.

20.3.3.3 Definition of “High Temperature” for Metallic Materials

For the purposes of this assessment, a “high temperature” for metallic materials is defined as that which would necessitate the design to account for creep effects.

Creep is plastic deformation in a material that occurs over a period of time at a stress below the elastic limit

Creep normally occurs in three stages called Stage 1, 2 and 3 creep

Stage 3 creep is also called tertiary creep

Stage 2 creep is normally linear and Stages 1 and 3 are normally defined by various non-linear functions depending on the material and creep model used

Design basis is given in ASME Section III, Subsection NH; and Section VIII, Div. 1 and 2

2 Based on the present assessment, it is recommended that non-replaceable components be limited to ~850ºC.

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For ferritic alloys, creep effects normally start about 400-500C

For Ni-base alloys, creep effects normally start about 500-700C

20.3.3.4 Assessment Input Requirements

Assessment requirements for this evaluation are given below:

Nominal 950ºC reactor outlet temperature (ROT)/ 350ºC reactor inlet temperature (RIT)

Nominal 900ºC secondary IHX outlet temperature

Maximum 300ºC secondary inlet temperature for indirect cycle with all reactor heat output to IHX

Maximum 450ºC (likely but TBD) secondary inlet temperature for other designs

He in primary and secondary loops

Primary loop pressure - 9 MPa

Primary to secondary loop delta P - essentially pressure balanced with slight positive pressure on secondary side

Order for IHX component by end of fiscal year (EOFY) 2012

Design life greater than or equal to 10 years with a target of 20 years (depending on size, design and other factors)

Target operating capacity - 95%

20.3.3.5 IHX Design Considerations

Several different potential plant design configurations for the NGNP with either direct or indirect power conversion cycles and integrated IHX designs were proposed and evaluated by [Ref. 20.3.3-3]. These configurations included IHX designs in parallel or in series with the NGNP power conversion system. In the serial designs, the total primary system flow from the reactor outlet passes through the IHX where approximately 50 MWt is transferred to the intermediate loop to drive the hydrogen production process. In these designs, heat is extracted from the primary fluid at the highest possible temperature (the reactor outlet temperature) for delivery to the hydrogen production process, while the power conversion system receives a slightly lower temperature fluid. In the parallel flow designs, the flow from the reactor outlet is split with a small fraction of the flow (approximately 10%) going to the IHX to drive the hydrogen production process, while the majority of the flow is delivered to the power conversion system for electrical power production. In these designs, both the hydrogen production process and the power conversion system receive the highest possible temperature fluid. Harvego [Ref. 20.3.3-4] has discussed the possible configurations for the design of an IHX for the NGNP and established the pros and cons of each configuration. Based on the design, he also established the flow rates, temperature distributions through the loops, and other IHX requirements.

The purpose of the IHX in the NGNP is to transfer heat from the nuclear reactor to the process heat facilities and, in some arrangements, to the electrical plant. One of the process heat facilities being considered is a hydrogen production plant. Due to safety concerns, the hydrogen production facility cannot be integrated into the nuclear power production plant and the heat generated in the reactor may need to be transported over significant distances to the hydrogen

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production plant [Ref. 20.3.3-5]. The IHX must be robust enough to effectively transfer the heat from the reactor outlet helium at 950°C to the secondary system. The hydrogen production facility requires a minimum temperature of 800°C for the thermo-chemical production of hydrogen (e.g., HyS or S-I cycles) and about 700°C for high temperature electrolysis of water [Ref. 20.3.3-1]. Therefore, the components of the heat transport system will be subjected to elevated temperatures for long times where adequate and reliable performance of materials is critical. This section addresses several of the key issues relating to IHX materials readiness, codes and standards readiness, design data needs, further research and development on materials and implications on the NGNP preconceptual design

Both conventional shell-and-tube and compact heat exchangers are considered in this assessment. Shell and tube exchangers are generally built of cylindrical tubes (in either straight or helical configurations) in a cylindrical shell with the tube bundle axis parallel to that of the shell. One fluid flows inside the tubes and the other flows across and/or along the outsides of the tubes in a counterflow arrangement for maximum effectiveness. The major components of this exchanger are the tubes, shell, front-end head, rear-end head, baffles and tube-sheets. Shell and tube heat exchangers can be very efficient heat transfer devices; however, the most significant issues with this type of HX are their size and weight. A 10MWt prototype IHX for the German process heat program was fabricated in the 1980s, satisfied all specified parameters and operated in excess of 900ºC ; however, the unit weighed about 135 tons. A corresponding unit for an indirect cycle 400-500MWt NGNP would be too large to be considered a viable option. Design rules for shell and tube HXs and associated pressure vessels are given in ASME Section VIII, Division 1, Part UHX. Alternative rules that permit higher design stresses are given in Section VIII, Division 2. Examples of shell and tube HXs are given in Figure 20.3.3-1 and Figure20.3.3-2 [Ref. 20.3.3-6].

SupportBrackets

Tubes

ShellBaffles

End Bonnet

Tubesheet

SupportBrackets

Tubes

ShellBaffles

End Bonnet

Tubesheet

(Photo From API Heat Transfer)

Straight-Tube HX

SupportBrackets

Tubes

ShellBaffles

End Bonnet

Tubesheet

SupportBrackets

Tubes

ShellBaffles

End Bonnet

Tubesheet

(Photo From API Heat Transfer)

Straight-Tube HX

Figure 20.3.3-1 Example of Tube and Shell Heat Exchanger with Straight Tubes

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Secondary helium(to SPWC)

Secondary helium(from SPWC)

Primary helium(from reactor)

Primary helium(to reactor)

Primary helium(to HGC)

Primary helium(from HGC)

: Primaryhelium

Secondary HeInlet nozzle

Manhole

Tube supportassembly

Central hotgas duct(Center pipe)

Hot header

Helically-coiledheat transfer tube

Thermalinsulation

Outer shell

Inner shell

Cold header

Secondary helium double nozzle

: Secondaryhelium

Key IHX Parameters

Vertical, helically coiled, counter flow

Type

Helium / HeliumPrimary / Secondary coolant

Hastelloy XRTubes

Hastelloy XRHot header

31.8mmO. D.

2 1/4Cr-1Mo steel

11.0m

2.0m

Hastelloy XR

3.5mm

96

(Inlet) 300oC

(Outlet) 775 860 C *

(Inlet) 850 950 C*

(Outlet) 390oC

14t/h 12t/h*

15t/h 12t/h*

10MW

Secondary

Shell

Material

Total height

Shell outer diameter

Material

Thickness

Number

Heat transfer

tubes

Secondary

PrimaryCoolant temperature

PrimaryCoolant mass flow rate

Thermal Rating

* Rated operation High temperature test operation

Figure 20.3.3-2 Example of Tube and Shell Heat Exchanger with Helical Tubes

More recently, compact heat exchangers have been developed that provide for increased performance relative to their weight and volume. Compact heat exchangers typically provide at least an order of magnitude improvement in surface compactness (m2/m3) and heat transfer compactness (MWt/m3) relative to shell and tube heat exchangers (Figure 20.3.3-3) [Ref. 20.3.3-7]. A common design feature to achieve such compactness is small channel size.

Included among compact heat exchangers are plate-fin (Figure 20.3.3-4 [Ref. 20.3.3-8] and Figure 20.3.3-5), primary surface (Figure 20.3.3-6 [Ref. 20.3.3-9]) and etched-plate (Figure 20.3.3-7, Figure 20.3.3-8) designs. In plate-fin heat exchangers, the primary and secondary fluids are separated by plates that are seal welded at the edges (Figure 20.3.3-4).Thin corrugated sections comprising fins are typically incorporated between the plates and brazed to the plates on one or both sides. The plate-fin assemblies are stacked to form the complete heat exchanger (Figure 20.3.3-5).

Primary surface heat exchangers are distinguished from plate-fin designs in that the corrugated fins themselves separate the primary and secondary fluids (Figure 20.3.3-6).

The most advanced example of etched plate heat exchangers is the Printed Circuit Heat Exchanger (PCHE) developed by the Heatric Division of Meggitt (UK) Ltd [Ref. 20.3.3-10, Ref. 20.3.3-11, Ref. 20.3.3-12]. The PCHE consists of metal plates on the surface of which

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millimeter-size semicircular channels are chemically etched. Subsequently, the plates are diffusion bonded together to fabricate an HX core. Flow distributors are integrated into the plates or welded outside the core, depending on the design. Several PCHE concepts have been developed by Heatric and a plate-type configuration, illustrated in Figure 20.3.3-7 and Figure20.3.3-8, has been selected for present analysis. In this configuration, flow distributors are integrated within the plates. Between the inlet and outlet flow distribution regions, the flow is purely counter-flow.

The internal configuration of a PCHE is information proprietary to Heatric. Each PCHE is a custom built heat exchanger in that the PCHE technology allows variation of configuration parameters (channel diameter, plate thickness, channel angles, and so on) to fit the specified task. The PCHE unit size is limited to about 60 MWt/unit [Ref. 20.3.3-12]. This unit size actually represents several sub-units of about 1.5 m x 0.6 m (maximum) on plate dimension and 0.6 m (maximum) on stack height that have been connected by headers [Ref. 20.3.3-13]. The weight/MWt for the tube and shell HX and the PCHE is about 13.5 tons/MWt and 0.2 tons/MWt, respectively [Ref. 20.3.3-12]. This represents a factor of about 68X for weight, a factor estimated to be about 100X for volume compared to a tube and shell HX/PCHE.Assuming approximately equal primary and secondary pressures, a pressure vessel used with a

plate type HX could, if properly designed, act to reduce P and, hence, steady state stress to near zero by enclosing the HX in a pressurized environment. Another factor that favors the PCHE is that the size of leaks that are likely to occur between the primary and secondary sides would be about 2 orders of magnitude less for the PCHE compared to the tube and shell. This results because the most likely leak from a PCHE would be from a semicircular passage with a radius of 0.6 mm versus a round tube with a diameter of about 15mm [Ref. 20.3.3-12]. Disadvantages of this design are (1) the susceptibility to very high thermally induced stresses during transients, particularly at the semi-circular channel corners, (2) inspection, (3) repair and (4) the lack of an ASME design basis.

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Figure 20.3.3-3 Compact Heat Exchanger Performance

Figure 20.3.3-4 Brazed Plate-Fin Recuperator Cross-Section

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Figure 20.3.3-5 Plate-Fin Recuperator Assembly

Figure 20.3.3-6 Corrugated Foil Pattern for Primary Surface Recuperator

(Courtesy Ingersoll-Rand)

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Figure 20.3.3-7 Cross-section through Heatric PCHE

Figure 20.3.3-8 Flow Path through PCHE

(Courtesy Heatric)

(Courtesy Heatric)

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Table 20.3.3-1 Summary of Design Tradeoffs for Evaluated HX Types

Metric Shell & Tube Plate-Fin & Prime Surface PCHE

Compactness (m

2/m

3 & MW/m

3 )

Poor Best Good

Cost (tons/MWt) Poor: (13.5 tons/MWt) Unlikely to be commercially viable

Best: Most compact, least materials

Good: (0.2 tons/MWt) Estimated to be ~1/68 that of S&T

Experience Base HTTR, German PNP Development

Conventional GT recuperators

PBMR DPP Recuperator, other commercial products

Robustness Best: Simple cylindrical geometry, stress minimized in HT area

Worst: Thin foils; stressed welds in pressure boundary; stress risers in pressure boundary welds; Small material and weld defects more significant

Good: Thicker plates; local debonding does not immediately affect pressure boundary; potential for higher transient thermal stresses vs. P-F

Inspection and Maintenance

Design facilitates inspection and plugging of individual tubes

Inspection and maintenance difficult or impractical below module level

Inspection and maintenance difficult or impractical below module level

HX Integration Headers and HX-vessel integration demonstrated

More difficult HX integration with multiple series/parallel modules

More difficult HX integration with multiple series/parallel modules

Code Basis for Design

Existing Sect VIII Code basis for tubular geometries

No existing Code basis No existing Code basis

A summary of design tradeoffs related to the heat exchangers discussed above is provided in Table 20.3.3-1 . Taking into account these tradeoffs, the PCHE has been selected on a preliminary basis for the NGNP IHX pre-conceptual design. The shell & tube HX was eliminated as not being commercially viable for a large IHX. The PCHE was judged to be more robust than other compact designs with a solid basis of commercial experience, albeit at lower temperatures. Tradeoffs include: (1) More difficult inspection and maintenance, and (2) Need to establish design basis for Code acceptance. Additional discussion regarding materials and code issues is given in other sections.

20.3.3.6 Metallic Materials Assessment

The following factors have the most impact on the selection of metallic alloys for application to the IHX:

ASME Code acceptance (Section III preferably or Section VIII)

Adequate data base for the temperature region of the IHX

The data base must include mechanical properties of small grain size samples and diffusion bonds if a plate type heat exchanger (HX) is selected

Must be able to be easily welded and/or diffusion bonded (plate type HX)

Must be able to be formed, machined or etched if a plate type HX is selected

Adequate creep rupture and mechanical properties in the region of 850-950C

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Must be commercially available in large quantities at reasonable cost

Must be available in multiple forms such as plate, tubing, forgings, etc.

Must be able to fabricate into thin sheets if a plate type HX is used

Must have reasonably stable properties during exposure to high temperatures for long time periods (thermal ageing)

Must be able to resist the corrosion effects of an impure He environment at high temperature

Must have reasonably stable and predictable mechanical and corrosion properties and microstructure over multiple heats within the ASTM/ASME chemical specification range for the alloy

Should be a part of an ASME Code basis for the design of the HX

20.3.3.6.1 Evaluation of Specific High Temperature Alloys

A large number of alloys that could be potentially useful for VHTR IHX fabrication are shown in Table 20.3.3-2 and were originally evaluated as a part of the NGNP Materials Program [Ref. 20.3.3-13]. Most of the alloys noted are not ASME Code materials and some are specialty alloys and may not generally be available in multiple forms. Most of the alloys noted also have a limited database and are not considered mature alloys (those that have been used in multiple high temperature applications for many years). Some of the alloys noted are ASME Code materials, have reasonably large databases and have been used for multiple high temperature applications. Most of the alloys have no database for high temperature impure Helium exposure. Selected mechanical properties of several alloys from these tables that are listed in the ASME Code are given in Table 20.3.3-3.

Haynes 214 is not discussed in this report because it is not an ASME Code material; however, this alloy has a stress rupture strength at 980ºC for 10,000 hours slightly less than Hastelloy X and has the highest resistance to oxidation compared to all other metallic alloys due to the formation of an adherent Al2O3 surface film. Only Alloy 617 (among the alloys evaluated) forms this type of oxide film at high temperatures, but it is less adherent than the film formed on Haynes 214. The other alloys discussed form films that are primarily Cr2O3, which are less stable at high temperature in air but have adequate resistance in high temperature exposure to impure helium.

Other cobalt based alloys such as Haynes 188 were not considered even though they have excellent high temperature mechanical properties for reasons that will be discussed later.

20.3.3.6.1.1 Haynes 556

Haynes 556 alloy is an iron-nickel-chromium-cobalt alloy that has excellent high temperature mechanical properties and resistance to sulfidizing, carburizing and chlorine bearing environments. This alloy has excellent forming and welding characteristics and, due to good ductility, can also be formed by cold working. This alloy is furnished in the solution heat treated condition and is a solid solution high temperature alloy that contains about 31% iron and about

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Table 20.3.3-2 Alloys Considered for NGNP High Temperature Applications

Nominal UNS Common Existing Data Helium

Composition Number Name Max Temp ( C) Experience

21Ni-30Fe-22Cr-

18Co-3Mo-3W

18Cr-8Ni S30409 304H SS 870 Yes

16Cr-12Ni-2Mo S31609 316H SS 870 Yes

16Cr-12Ni-2Mo 316FR 700

18Cr-10Ni-Cb S34709 347H SS 870

18Cr-10Ni-Cb 347HFG 760

18Cr-9Ni-3Cu-Cb-

N

Super 304 1000

15Cr-15Ni-6MnCb-

Mo-V

S21500 Esshete 1250 900

20Cr-25Ni-Cb NF 709 1000

23Cr-11.5Ni-N-B-

Ce

NAR-AH-4 1000

Ni-20Cr-Al-Ti-Y2O3 NO7754 Inconel MA

754

1093

Ni-30Cr-Al-Ti-Y2O3 Inconel MA

754

1093

Fe-20Cr-4.5Al-

Y2O3

S67956 Incoloy MA956 1100

R30556 Haynes 556 Section VIII,

Div 1-899

Nominal UNS Common Existing Data Helium

Composition Number Name Max Temp ( C) Experience

Ni-16Cr-3Fe-4.5Al-

Y

Haynes 214 1040

63Ni-25Cr-9.5Fe-

2.1Al

N06025 VDM 602CA 1200

Ni-25Cr-20Co-Cb-

Ti-Al

Inconel 740 815

60Ni-22Cr-9Mo-

3.5Cb

N06625 Inconel 625

53Ni-22Cr-14W-

Co-Fe-Mo

N06230 Haynes 230 Section VIII,

Div 1-982

Ni-22Cr-9Mo-18Fe N06002 Hastelloy X Section VIII,

Div1-899

Yes

Ni-22Cr-9Mo-18Fe Hastelloy XR 1000 Yes

46Ni-27Cr-23Fe-

2.75Si

N06095 Nicrofer 45

45Ni-22Cr-12Co-

9Mo

N06617 Inconel 617 Section VIII,

Div 1-982

Yes

Ni-23Cr-6W Inconel 618E 1000

Ni-33Fe-25Cr N08120 HR-120 Section VIII,

Div 1-899

35Ni-19Cr-1 1/4Si N08330 RA330 Section VIII,

Div 1-899

33Ni-42Fe-21Cr N08810 Incoloy 800H Section III, Div

1-760

Yes

33Ni-42Fe-21Cr N08811 800HT Section VIII,

Div 1-899

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Table 20.3.3-3 Refined Alloy List Based on Listing in ASME Code Section II

Alloys UNS No

Max

Allowable

Code Stress

at 899C

(MPa)

Max Code

Allowable

Temperature

(C)

Ultimate

Tensile

Strength at

870C (Mpa)

Yield

Strength at

870C (Mpa)

10000 hour

rupture

strength at

870C (Mpa)

10000 hour

rupture

strength at

980C (Mpa)

Stress for

1% Creep

in 10000

hours at

980C

Stress

Rupture

Life

(Hours),

980C at

14MPa

Haynes

556 R30556 12 899 330 195 34 13 11 7500

Haynes

230 N06230 10.4 982 385 225 39 7.6 NA 5000

Hastelloy

X N06002 8.3 899 255 180 27 10 7 2100

Inconel

617 N06617 12.4 982 275 205 36 15 10 10000

HR-120 N08120 9.7 899 325 185 40 13 8 10000

RA-330 N08330 3.3 899 NA 110 12 4 1 130

Incoloy

800H N08810 5.9 899 110 110 24 NA NA 920

Incoloy

800HT N08811 6.3 899 110 110 24 8 NA NA

20% nickel. Haynes 556 is available in a wide variety of product forms and specifications and is covered by ASME Section VIII, Division 1 up to 900ºC. This alloy has a very high resistance to gas carburizing environments but has not been tested for resistance to an impure helium environment at high temperatures. This alloy is less mature compared to Alloys 617, 230, X and 800H.

20.3.3.6.1.2 Haynes 230

Haynes 230 alloy is a nickel-chromium-tungsten alloy that has excellent high temperature mechanical properties and outstanding oxidization resistance. This alloy has excellent forming and welding characteristics and, due to good ductility, can also be formed by cold working. This alloy is furnished in the solution heat treated condition and is a solid solution high temperature alloy that contains about 57% nickel, about 22% chromium and about 14% tungsten. This alloy has excellent stability and resistance to grain coarsening following long time exposure at high temperatures and has a very low thermal expansion coefficient. This alloy does not precipitate embrittling second phases during high temperature exposure. Haynes 230is available in a wide variety of product forms and specifications and is covered by ASME Section VIII, Division 1 up to 982ºC. This alloy is very mature compared to Alloys 556, HR-120 and RA-330, and is slightly less mature compared to Alloys 617 and 800H. The French are currently performing an extensive evaluation of this alloy for application to the ANTARES VHTR IHX design.

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20.3.3.6.1.3 Hastelloy X and XR

Alloy X is a nickel-chromium-iron-molybdenum alloy that has moderately good high temperature mechanical properties and outstanding oxidization resistance. This alloy has excellent forming and welding characteristics and, due to good ductility, can also be formed by cold working. This alloy is furnished in the solution heat treated condition and is a solid solution high temperature alloy that contains about 47% nickel, about 22% chromium, about 18% iron and about 9% molybdenum.. This alloy can precipitate embrittling second phases during high temperature exposure above 700ºC. Alloy X is available in a wide variety of product forms and specifications and is covered by ASME Section VIII, Division 1 up to 900ºC . This alloy is very mature compared to Alloys 556, HR-120 and RA-330 and is slightly less mature compared to Alloys 617 and 800H. The Japanese conducted an extensive evaluation of Alloy X for application to the IHX of the HTTR demonstration that was subsequently constructed in Japan.In doing so, they developed an XR compositional variant of this alloy specifically designed to resist the oxidizing and carburizing effects of impure helium at high temperatures.

20.3.3.6.1.4 Inconel 617 and 617CCA

Alloy 617 is a nickel-chromium-cobalt-molybdenum alloy that has the highest high-temperature mechanical properties (compared to the other alloys evaluated) and outstanding oxidization resistance. This alloy was originally developed to optimize resistance to high temperature creep. This alloy has excellent forming and welding characteristics and, due to good ductility, can also be formed by cold working. This alloy is furnished in the solution heat treated condition and is a solid solution high temperature alloy that contains about 44% nickel, about 22% chromium, about 13% cobalt and about 9% molybdenum. This alloy has excellent stability and resistance to grain coarsening following long time exposure at high temperatures and has a low thermal expansion coefficient. This alloy does not precipitate embrittling second phases during high temperature exposure; however, the alloy does show some loss of fracture toughness as a function of aging time at high temperatures. Alloy 617 is available in a wide variety of product forms and specifications and is covered by ASME Section VIII, Division 1 up to 982ºC.This alloy is the most mature of the alloys evaluated, with the exception of Alloy 800H, which has comparable maturity. The French are currently performing an extensive evaluation of this alloy for application to the ANTARES VHTR IHX design. Variability in high temperature mechanical properties for different heats of this alloy has been an issue in the past. This is due in part to the long history of this alloy, significant changes that have taken place over the years in melting practice and the relatively wide chemical specification range for this alloy. This variability has been extensively addressed by the Ultrasupercritical (USC) Fossil Boiler R&D Program funded by the DOE. The USC program has developed a compositional variant to this alloy (Alloy 617 CCA) that produces more consistent mechanical properties at high temperature.An attempt to develop an alternate compositional variant (Alloy 617C) of this alloy for VHTR applications was made by the NGNP Materials Program; however, this alternate specification has not proven to be viable to date.

20.3.3.6.1.5 Haynes HR-120

Haynes HR-120 is an iron-nickel-chromium alloy that has excellent high temperature mechanical properties and resistance to sulfidizing, carburizing and oxidizing environments.

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This alloy has excellent forming and welding characteristics and, due to good ductility, can also be formed by cold working. This alloy is furnished in the solution heat treated condition and is a solid solution high temperature alloy that contains about 33% iron, about 37% nickel and about 25% chromium. HR-120 is available in a wide variety of product forms and specifications and is covered by ASME Section VIII, Division 1 up to 900ºC . This alloy has a good resistance to gas carburizing environments but has not been tested for resistance to an impure helium environment at high temperatures. This alloy is less mature compared to Alloys 617, 230, X and 800H.

20.3.3.6.1.6 Haynes RA-330

Haynes RA-330 is an iron-nickel-chromium alloy that has poor high temperature mechanical properties and fair resistance to sulfidizing, carburizing and oxidizing environments. This alloy has excellent forming and welding characteristics and, due to good ductility, can also be formed by cold working. This alloy is furnished in the solution heat treated condition and is a solid solution high temperature alloy that contains about 48% iron, about 35% nickel and about 18% chromium. RA-330 is available in a wide variety of product forms and specifications and is covered by ASME Section VIII, Division 1 up to 900ºC . This alloy has not been tested for resistance to an impure helium environment at high temperatures. This alloy is less mature than Alloys 617, 230, X and 800H.

20.3.3.6.1.7 Alloy 800H

Alloy 800H is an iron-nickel-chromium alloy that has fair high temperature mechanical properties and fair resistance to sulfidizing, carburizing and oxidizing environments. This alloy has excellent forming and welding characteristics and, due to good ductility, can also be formed by cold working. This alloy is furnished in the solution heat treated condition and must be solution annealed at about 1093ºC in order to obtain a stable austenitic structure. This alloy is a solid solution high temperature alloy that contains about 43% iron, about 33% nickel and about 22% chromium. 800H is available in a wide variety of product forms and specifications and is covered by ASME Section VIII, Division 1 up to 982ºC. It is the only alloy in the group that is listed for use in ASME Section III, Subsection NH for a maximum temperature up to 760ºC. This alloy has been tested for resistance to an impure helium environment at high temperatures. This alloy is the most mature of the alloys evaluated, with the exception of Alloy 617, which has comparable maturity.

20.3.3.6.2 Further Evaluation of Alloys

Further evaluation of the properties of these alloys was made. The results of this evaluation are given in Table 20.3.3-4 and Table 20.3.3-5.

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Table 20.3.3-4 Selected Properties of Alloys Evaluated

Alloys UNS No

Max

Allowable Code Stress at 899C (MPa)

Max Code Allowable Temperature (C)

Ultimate

Tensile Strength at 870C (Mpa)

Yield Strength at 870C (Mpa)

10000 hour rupture strength at 870C (Mpa)

10000 hour

rupture strength at 980C (Mpa)

Stress for 1% Creep in 10000 hours at 980C

Stress Rupture Life (Hours), 980C at 14MPa

Haynes 556 R30556 12 899 330 195 34 13 11 7500

Haynes 230 N06230 10.4 982 385 225 39 7.6 NA 5000

Hastelloy X N06002 8.3 899 255 180 27 10 7 2100

Inconel 617 N06617 12.4 982 275 205 36 15 10 10000

HR-120 N08120 9.7 899 325 185 40 13 8 10000

RA-330 N08330 3.3 899 NA 110 12 4 1 130

Incoloy 800H N08810 5.9 899 110 110 24 NA NA 920

Incoloy 800HT N08811 6.3 899 110 110 24 8 NA NA

Table 20.3.3-5 Selected Properties of Alloys Evaluated

Alloys

Incipient Melting

Point

Thermal

Conductivity at 900C

(W/m)xK

He Corrosion

Data Base Welding

Typical

ASTM Grain

Size

Relative Cost-

$Alloy/$304SS Available

% of RT

Tensile Strength

following Aging at 982C

for 1000 hours

Mils of

Penetration after 55 Hours in Ar-

5%H2-1% CH4

Haynes 556 1329 27.2 No

Readily

Weldable 5-6 8.5

Sheet, Plate,

Round Bar

32 (16000

hours) NA

Haynes 230 1302 26.4 Yes

Readily

Weldable 5-6 NA All 37 (b) NA

Hastelloy X 1260 27.2 Yes

Some Welding

Problems 5-6 4.8-5.6

Sheet, Plate,

Round Bar 12 (a) NA

Inconel 617 1332 26.7 Yes

Readily

Weldable 1-4 NA All 39 © NA

HR-120 1302 26.2 No

Readily

Weldable 3-6 3.5

Sheet, Plate,

Round Bar 99 25RA-330 1343 NA No NA 4-6 2.6-3.0 NA NA 35

Incoloy 800H 1302 NA YesReadily Weldable 2-4 2.6-3.0 All NA 30

Incoloy 800HT 1302 NA Yes

Readily Weldable 2-4 2.6-3.0 All NA NA

(a) % of Impact Strength Retained (compared to RT) following aging for 16000 hours at 871C

(b) 32 % elongation retained following 8000 hour exposure at 982C and 36% impact strength after 16000 hours at 982Cc 39% of impact strength following 12000 exposure at 760C

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Alloys 230 and 617 have the highest ASME Code temperature rating (982ºC). The four alloys with the highest maximum allowable Code stress at 900ºC are Alloys 617, 556, 230 and HR-120 (12.4, 12, 10.4 and 9.7 MPa, respectively). The two alloys Code-rated for service at 982ºC (Alloys 617 and 230) have Code allowable stresses of only 5 and 3.1 MPa, respectively.Therefore there is little design margin at this temperature. The four alloys with the highest maximum allowable Code stress at 900ºC (Alloys 617, 556, 230 and HR-120) also have the highest 10,000 hour rupture strength at 980ºC (15, 13, 7.6 and 13 MPa, respectively). The ranking of these alloys by stress rupture life (hours) at 14 MPa at 980ºC are Alloys 617/HR-120 (Rank 1), Alloy 556 (Rank 2) and Alloy 230 (Rank 3) The incipient melting point and thermal conductivities of these alloys are similar. Hastelloy X precipitates detrimental second phases following long term high temperature exposure; the other alloys have good long term stability except HR-120 which may also be susceptible under some conditions. All of these alloys are readily available in multiple forms. Therefore, based on these criteria, the alloys would rank overall: Alloy 617, HR-120, Alloy 556, Alloy 230 and Hastelloy X. Alloys RA-330 and Alloy 800H are not considered viable for the IHX due to somewhat inferior high temperature strength.

The Japanese selected Hastelloy XR for fabrication of the heat transfer tubes and hot headers for use in a helical tube and shell IHX for the HTTR. Hastelloy XR is a refined chemistry specification of Hastelloy X that was developed over several years, primarily to resist the corrosion effects of high temperature impure helium used in the HTTR. In this application, Hastelloy XR has a design temperature rating of about 950ºC (1000ºC maximum allowable temperature) and a design pressure rating of 0.29MPa (absolute). Total weight of Hastelloy XR used for the 10MWt IHX of the HTTR was about 20 tons (20,000kg) with the weight of each ingot about 3 tons. The Japanese evaluated other alloys, including Alloy 617, prior to the development of Hastelloy XR. The HTTR represents the most recent actual application of resources for the design, materials and fabrication of an IHX for a VHTR and, therefore, needs to be seriously considered. The creep rupture life to failure for Alloys 617, 230, 800H and Hastelloy X is compared in Figure 20.3.3-9.

Alloys 617 and 556 have the highest Co content among the four alloys. The high Co content is undesirable for the IHX application because surface layers (oxides) that form on the IHX surface in the primary loop could become dislodged and form Co-60 by neutron activation following circulation in the reactor. This could result in a maintenance problem for equipment that became contaminated. The high W content in Alloy 230 is also undesirable for the same reasons. Iron, nickel and chromium also could potentially become activated; however, these activation products would produce fewer problems. In general, Alloy 617 is the most resistant of the alloys to surface oxidation. HR-120 and Alloy 556 contain significant quantities of iron; Hastelloy X also contains significant iron. The corrosion of alloys with significant iron content has not been investigated (except Hastelloy X and XR) for the effects of impure helium corrosion.

The ASTM standard specification range for these alloys and their compositional variants are given in Table 20.3.3-6.

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Creep Rupture at 10000 hours

0.0

50.0

100.0

150.0

200.0

250.0

300.0

500.0 600.0 700.0 800.0 900.0 1000.0 1100.0

Temperature C

Str

ess M

Pa

800 H

Alloy 556

Alloy 230

Hastelloy X

Alloy 617

Alloy 214

HR-120

Figure 20.3.3-9 Comparison of Creep Rupture Life to Failure for Alloys Evaluated

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Table 20.3.3-6 ASTM Specification Range for Alloys Evaluated

Heat Ni Cr Co Mo Fe Mn Al C Cu Si S Ti B N P W Ta La Zr Cb Y

617 min 44.5 20 10 8 0 0 0.8 0.1 0 0 0 0 0 0 0 0 0 0 0 0 0

617 max Bal 24 15 10 3 1 1.5 0.2 0.5 1 0 0.6 0 0 0 0 0 0 0 0 0

617C min 44.5 22 13 9 0 0 1.2 0.1 0 0 0 0.4 0 0 0 0 0 0 0 0 0

617C max Bal 24 15 10 1 1 1.4 0.1 0.2 0.3 0 0.6 0 0 0 0 0 0 0 0 0

Haynes 230

(nomimal)

57* 22 5* 2 3* 0.5 0.3 0.1 0 0.4 0 0 .015* 0 0 14 0 0.02 0 0 0

HX min Bal 20.5 0.5 8 17 0 0 0.1 0 0 0 0 0 0 0 0.2 0 0 0 0 0

HX max Bal 23 2.5 10 20 1 0 0.2 0 1 0 0 0 0 0 1 0 0 0 0 0

XR min Bal 20.5 0 8 17 0.8 0 0.1 0 0.3 - 0 0 0 0 0.2 0 0 0 0 0

XR max Bal 23 2.5 10 20 1 0.1 0.2 0.5 0.5 0 0 0 0 0 1 0 0 0 0 0

800H min 30 19 0 0 Bal - 0.2 0.1 0 0 0 0.2 0 0 0 0 0 0 0 0 0

800H max 35 23 0 0 Bal 0.2 0.6 0.1 0.8 1 0 0.6 0 0 0 0 0 0 0 0 0

617 CCA Min Bal 21 11 8 0 0 0.8 0.1 0 0 0 0.3 0 0 0 0 0 0 0 0 0

617 CCA Max Bal 23 13 10 1.5 0.3 1.3 0.1 0.1 0.3 0 0.5 0 0.1 0 0 0 0 0 0 0

Alloy 556

(nominal)

20 22 18 3 Bal 1 0.2 0.1 0 0.4 0 0 0 0.2 0 2.5 0.6 0.02 0.02 0 0

HR-120

(nominal)

37 25 3* 2.5* Bal 0.7 0.1 0.05 0 0.6 0 0 0.004 0.2 0 2.5* 0 0 0 0.7 0

Haynes 214

(nominal)

Bal 16 0 0 3 0.5 4.5 0.05 0 .2* 0 0 .01* 0 0 0 0 0 .1* 0 0.01

*=Maximum

As previously noted, Alloy 617 contains the widest specification range for the primary elements. The wide specification range has resulted in heats of Alloy 617 being produced that did not have uniform properties, and this is considered undesirable for the IHX application.

The Alloy 617C controlled material specification [Ref. 20.3.3-15] was developed for VHTR materials applications, based on the analysis of mechanical properties and chemical compositions of historical data from various heats. The intent of the controlled specification was to tighten the ASTM specification to produce a more predictable material for testing, as opposed to optimizing the corrosion properties of Alloy 617 in high temperature impure helium. The current recommended melting practice (solution anneal at a minimum temperature of 11500C for a time commensurate with section size followed by water quench; melting practice is VIM+ESR and heat analysis should be checked after ESR) was not uniformly followed in older Alloy 617 heats. It is not clear at this point if the Alloy 617C material can be reliably formed into plates, due to various issues with hot working revealed in the small laboratory heats produced to date.

Given this result, the Alloy 617CCA specification developed previously as a part of the USC program for high temperature applications for fossil power is currently being investigated. It is known that this material can be hot formed. Alloy 617 CCA is being extensively examined

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by the USC Program and, to date, the results are favorable. Creep rupture data for Alloy 617 compared to Alloy 617CCA is given in Figure 20.3.3-10 and Figure 20.3.3-11. (Note that in Figure 20.3.3-10 the arrows indicate samples that were removed from testing without failure.)

The effects of heat to heat variation and environmental effects on Alloy 617 produced and tested in 1984 are given in Figure 20.3.3-12 and Figure 20.3.3-13. High temperature creep data obtained for Alloy 230 compared to Hastelloy X and Alloy 617 is given in Figure20.3.3-14 and Figure 20.3.3-15 [Ref. 20.3.3-16] (red stars indicate French Alloy 230 data; other data are from INCO and Haynes). A comparison of average creep-to-rupture data for Alloys 617 and 230 is plotted in Figure 20.3.3-16. Major sources of creep data for Alloy 617 are summarized in Table 20.3.3-7 and Table 20.3.3-8 [Ref. 20.3.3-17].

60

70

80

90100

200

300

400

500

21,000 22,000 23,000 24,000 25,000 26,000

600 650 700 750

Temperature (oC) for Rupture in100,000 hours

Larson Miller Parameter (LMP) = Temp(K) x (log tr+ 20)

Str

ess (

MP

a)

Line = Std. 617

Points = 617 CCA

60

70

80

90100

200

300

400

500

21,000 22,000 23,000 24,000 25,000 26,000

600 650 700 750

Temperature (oC) for Rupture in100,000 hours

Larson Miller Parameter (LMP) = Temp(K) x (log tr+ 20)

Str

ess (

MP

a)

60

70

80

90100

200

300

400

500

21,000 22,000 23,000 24,000 25,000 26,000

600 650 700 750

Temperature (oC) for Rupture in100,000 hours

Larson Miller Parameter (LMP) = Temp(K) x (log tr+ 20)

Str

ess (

MP

a)

Line = Std. 617

Points = 617 CCA

Figure 20.3.3-10 Creep Rupture Data That Compares Alloy 617 and 617CCA

The Alloy 617 CCA has slightly higher creep rupture properties compared to standard Alloy 617.

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0

1

2

3

4

5

6

7

8

0 200 400 600 800 1000

cre

ep (%

)

time (h)

std 617

617CCA

800 C100 MPa

0

1

2

3

4

5

6

7

8

0 200 400 600 800 1000

cre

ep (%

)

time (h)

std 617

617CCA

800 C100 MPa

Figure 20.3.3-11 Creep Rupture Data That Compares Alloy 617 and 617CCA

The Alloy 617 CCA has slightly higher creep rupture properties compared to standard Alloy 617.

0

2

4

6

8

10

0 5000 1000 0 15000 2000 0 25000

H eat 1

H eat 2

H eat 3

CR

EE

P S

TR

AIN

, (%

)

T IM E , (h )

A lloy617 Enn is84S pe cif ica tionO R N L / W .R en

S tres s: 13 .5 M P a

E nviro n m e nt: H e lium

Figure 20.3.3-12 Creep Strain vs. Time for 3 Alloy 617 Heats in Helium at 13.5MPa Stress

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Note the heat to heat variation in the creep properties. Heat 3 has the most favorable creep properties and had a high Al content of 1.35% [Ref. 20.3.3-18].

Figure 20.3.3-13 Elongation at Rupture vs. Temperature for 3 Alloy 617 Heats in Air and Impure Helium

Specimens tested in air show more favorable properties and specimens tested in impure helium show effects of corrosion [Ref. 20.3.3-19].

Figure 20.3.3-14 Recent Alloy 230 High Temperature Creep Rupture Life Data Compared to Hastelloy XR

Haynes 230

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There is no significant difference in properties for times and temperatures tested [Ref. 20.3.3-16]

Figure 20.3.3-15 Recent Alloy 230 High-Temperature Creep Rupture Life Data vs. Alloy 617

There is no significant difference in properties for times and temperatures tested [Ref. 20.3.3-16]

Figure 20.3.3-16 Average Alloy 230 and 617 INCO and Haynes Creep Rupture Data at High Temperatures for Long Times

Haynes 230

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Alloy 230 creep properties are similar to Alloy 617 except at high temperatures and long times where Alloy 617 shows superior properties.

Table 20.3.3-7 Major Sources of Creep Data for Alloy 617

Source # of Tests Temp. Range Max Duration Min Stress

ORNL-HTGR 51 593 - 871°C 34,231 h 21 MPa

GE-HTGR 36 750 - 1100°C 28,920 h 9.6 MPa

Huntington Alloy 249 593 – 1093°C 40,126 h 6.2 MPa

German HTGR 294 800 – 1000°C ~20,000 h 8.2 MPa

Table 20.3.3-8 Known Creep Data for Alloy 617 at about 950ºC

Source # Tests # Tests> 500

Hours

Max Duration

Hours

Min

Stress

MPa

Min Creep

Rate (%/Hr)

Kihara 8 0 2115 24.5 1.70E-03

Baldwin 13 3 28920 20.7 4.50E-05

Huntington

Alloy

35 0 4788 13.8 1.50E-05

Schubert 62 6 ~20000 13.9 1.00E-04

Schneider 22 ?? ?? 30.6 2.00E-04

Osthoff 18 0 1000 8.2 4.00E-05

Ennis 19 6 ~20000 12.7 ??

Cook 9 2 6116 19.8 1.70E-03

Total Total Max Min Min

186 17 28920 8.2 1.50E-05

The next area that needs to be examined is the influence of helium coolant on the chemical compatibility of structural materials that are planned for use in the NGNP. Helium, because of its chemical inertness and attractive thermal properties, is used as a primary coolant in VHTRs. However, the primary coolant in an operating VHTR is expected to be contaminated by small amounts of gaseous impurities such as H2, H2O, CH4, CO, CO2 and O2 from a variety of sources, such as reactions of ingressed water and oil with core graphite, and outgassing of reactor materials. These impurities are projected to be at ppm levels in the helium coolant, but the upper bound would strongly depend on the level of purification used for the helium supply and the leak tightness of the reactor system.

Corrosion of structural alloys by these gaseous impurities at elevated temperatures can be significant. Past studies have shown that the corrosion of heat resistant materials such as austenitic stainless steels, Alloy 800H and Alloy 617 may involve oxidation, carburization, and decarburization, depending on the exposure temperature, carbon activity in the gas phase, and the alloy composition. Further, the corrosion process is dynamic in the sense that it is dictated by

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the exposure time, gas chemistry variations, integrity of the corrosion product scales, and presence of particulates in the gas phase.

The helium coolant in an operating VHTR makes a complete circuit from the graphite core to the heat exchangers or gas turbines and back to the core in several seconds. It is reported that the gas components in the coolant, via reaction with the graphite in the core and, to a limited extent, with themselves, will reach a steady state under this dynamic flow condition and may approach an equilibrium state with respect to the core [Ref. 20.3.3-20]. Equilibrium between the surfaces of metallic components and the gaseous impurities in the primary coolant helium is not expected to occur under these very fast flow conditions. Therefore, the carbon activity and oxygen partial pressure in the helium coolant, under such non-equilibrium conditions, will be determined by individual reactions that predominate in the gas mixture.

Although the gaseous impurities in a primary coolant environment may not be in equilibrium with themselves or with surfaces of metallic components, driving forces will exist for gas-metal interactions to occur. The extent to which these interactions will occur will be kinetically controlled, dictated by time, temperature, alloy chemistry and surface condition of the alloy. In such non-equilibrium conditions, potentials for gas-metal corrosion reactions may be determined through equilibrium thermodynamics by considering each individual chemical reaction that is possible between the metal and individual gaseous impurities.

From the structural materials standpoint, we are interested in reactions that can affect the corrosion loss and/or influence the mechanical integrity; reactions that can lead to processes such as oxidation, carburization, and decarburization are of interest. Carburization and decarburization processes are determined by the carbon activity in the gas mixture relative to that in the exposed metal surface. Similarly, the oxidation process is determined by the oxygen partial pressure in the environment relative to the stability of oxides of the constitutive elements that are present on the exposed metal surface. A detailed discussion on reactions between various gas species in helium and its influence on the thermodynamic activity of carbon and oxygen has been documented elsewhere [Ref. 20.3.3-13]. In summary form, the corrosion behavior is determined by comparing the potentials of oxygen and carbon in the gas with the stability of oxides and carbides in the alloy. The following gas reactions establish the oxygen partial pressure:

H2O H2 + 1/2O2

CO + H2 C + H2O

Carbon and oxygen partial pressures are coupled by the reaction:

CO C + 1/2O2

There is a critical value of partial pressure of CO (p*CO) that represents CO pressure in equilibrium with metal, oxide and carbide. Several photomicrographs that show the effects of impure helium exposure for 813 hours at 950ºC on Hastelloy X, Alloy 800H and Alloy 617 are

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shown in Figure 20.3.3-17, Figure 20.3.3-18 and Figure 20.3.3-19. These results are shown in summary form in Figure 20.3.3-20.

Figure 20.3.3-17 Hastelloy X Exposure with Relatively Little Cr Oxide Formation

Cr2O3 /Cr-Mn spinel is the layer between the alloy (white) and the mounting (dark grey), [10µm], [Ref. 20.3.3-21].

Figure 20.3.3-18 Alloy 800H Exposure with Relatively Greater Cr Oxide and Ti Oxide Formation and Some Internal Oxidation of Al

Oxide is the layer between the alloy (white) and the mounting (dark grey), [10µm], [Ref. 20.3.3-21].

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Figure 20.3.3-19 Alloy 617 Exposure with Cr Oxide and Ti Oxide Formation Similar to Alloy 800H and Some Internal Oxidation of Al

Oxide is the layer between the alloy (white) and the mounting (dark grey), [10µm], [Ref. 20.3.3-21].

Figure 20.3.3-20 Summary of French He Test Data at 950ºC and 813 Hours

In summary, the internal oxidation of Alloys 617 and 230 are related to the Ti and Al contents. As shown in Figure 20.3.3-20 [Ref. 20.3.3-21], Alloy 230 is more corrosion resistant than Alloy 617. Hastelloy XR revealed stable corrosion characteristics relative to the

conventional Hastelloy X even at 1000 C up to 20,000h in stimulated HTGR helium. This is

-80

-70

-60

-50

-40

-30

-20

-10

0

10

Th

ick

ne

ss

/de

pth

m)

Internal affected zone

Internal oxidation

Loose oxide

Compact oxide scale

A8

00

H

massive

internal

oxidation

IN6

17 H

ay

ne

s2

30

Ha

ste

llo

yX

PM

10

00

0

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due to the improvement of the stability of surface oxide film which consists of MnCr2O4 and Cr2O3 layers.

Detailed discussions of high temperature mechanical property regarding Alloys 617, 230, X and XR is given in [Ref. 20.3.3-22].

Initial conclusions regarding the refined list of alloys are given below:

Alloy 617 has more retained strength and creep resistance at the temperatures of interest

Hastelloy X and XR are the more resistant alloys to impure He corrosion at high temperatures

Alloy 556 has the highest resistance to gas carburization of any of the alloys evaluated

Alloy 230 has slightly less strength and creep resistance (compared to Alloy 617 at long times and high temperatures) but it shows (based on French testing) more resistance to impure He corrosion at high temperatures

Alloys HR-120 and Alloy 556 have very high retained strength and creep resistance at high temperatures, but they are 1/3 Fe and no one has studied these materials in high temperature impure He. However, they have several similarities to Hastelloy X (31-33% Fe versus 20-23% for Hastelloy, low or no Al and Ti) and therefore may perform well in impure He. These materials are the most immature of the four alloys and this would result in a longer R&D program

Hastelloy X has considerably less retained strength and creep resistance at high temperature

Incoloy 800H and 800HT creep properties are inferior to the other alloys in the IHX temperatures of interest; however, 800H is the only current ASME Section III alloy in the group

All of the other alloys that have been seriously evaluated are currently ASME Section VIII usage only, which is limited to non-nuclear applications

This indicates that there is a serious problem with the lack of usable ASME Section III alloys for the IHX application. This will be discussed in detail in the next section.

It is therefore concluded that if a new ASME Section III Code Case will need to be written for this application (discussed later), Alloys 617 and 230 should be considered the best available metallic alloys for this application if high retained strength and creep resistance at high temperature is a major factor and a relatively shorter R&D Program is a major consideration.

If the IHX design selected could tolerate a lower high temperature strength and creep resistance, then Hastelloy X or XR should be considered.

Hastelloy XR would require the transfer of the Japanese data base to be seriously considered (an agreement with the ASME for data base transfer has now been established but the extent of the information transfer would require further investigation).

If the length of the R&D Program is not a major factor, Alloy 556 should be seriously considered.

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20.3.3.6.3 Other Considerations

Low cycle fatigue properties need to be considered to assess the influence of thermal cycling during startup, shutdown and power changes. Thermal expansion associated with constraint (plate type HX design) will translate into thermal stress and therefore limit the fatigue life of the IHX. If a PCHE is selected, the alloy sheets would need to be capable of channel etching and diffusion bonding. It is known that this process can be performed for Alloy 617 and is being developed for Alloy 230 by Heatric. It is currently unknown whether HR-120, Alloy 556 and Hastelloy X could be processed in this manner. The development of Alloy 617 centered on the desire for maximum creep strength at elevated temperatures. Solution anneal temperatures were normally selected to obtain coarse grain material which optimizes creep strength. Smith and Yates [Ref. 20.3.3-23] performed a development program to optimize both low cycle fatigue (LCF) properties and creep properties on Alloy 617. It was shown that by using closely controlled thermo-mechanical processing a fine grain size (GS) alloy can be produced that possesses very good fatigue resistance with no loss in creep resistance. The best LCF properties were for Alloy 617 with a GS of 9.5. A peak alternating stress of 80MPa resulted in failure at 980ºC following 100,000 cycles. There is no equivalent LCF data available for Alloy 556. HR-120 has poor LCF properties at high temperature. Alloy 230 has excellent LCF strength. Hastelloy X and XR have inferior LCF properties compared to Alloy 230. A detailed discussion of LCF for Alloys 617, 230 and X is given in Natesan et al, 2006.

The mean coefficient of thermal expansion for the alloys noted below between room temperature and 1000ºC is given below in mm/(m·ºC):

Alloy 617: 11.6 (100ºC) - 16.3 (1000ºC)

Hastelloy X: 13.8 (100ºC) - 16.6 (1000ºC)

Alloy 230: 11.8 (100ºC) - 16.1 (1000ºC)

HR-120: 14.3 (100ºC) - 17.8 (1000ºC)

Alloy 556: 14.3 (100ºC) - 17.1 (1000ºC)

20.3.3.6.4 Final Recommendations

The final conclusion of this evaluation is that if maximum mechanical properties are required at high temperature for the IHX design, Alloy 617 is the best IHX alloy option. There are unverified indications that the more restrictive chemistry of the Alloy 617CCA specification developed through the USC Program may result in improved properties relative to the standard Alloy 617 specification. This should be verified. If slightly less tensile and creep strength could be tolerated at high temperature in the IHX design, Alloy 230 may become the best IHX alloy option on the basis of lower Co content and superior resistance to helium impurities.

Existing metallic materials can be applied in the temperature regime of the NGNP IHX, albeit with significant limitations:

Will require designs based on very low stresses during normal long-term operation

Transient-related stresses will be more significant in compact IHXs (needs further evaluation)

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Likely need to replace IHX core multiple times over 60-year design life of plant

Present metallic materials are likely not the optimum long-term solution for commercial process heat plants operating in the NGNP temperature range.

20.3.3.7 Ceramics Materials Assessment

Structural ceramics such as silicon carbide (SiC) and silicon nitride (Si3N4) have outstanding high temperature strength, plus they have higher thermal conductivity and lower thermal expansion than metals. These attributes make them attractive candidates for the NGNP IHX operating in the range 850 -1000ºC. Recuperators and heat exchangers made of ceramics are being developed for turbine, automotive, and fuel cell applications. OxyCube™ is a ceramic heat exchanger design developed at ORNL based on gel technology that does not require the joining of ceramic layers during fabrication. . Heat exchanger units have been fabricated from a monolithic sodium zirconium phosphate ceramic in collaboration with industry for fuel cell applications and can withstand temperatures up to 1200ºC [Ref. 20.3.3-24]. ORNL also has developed a ceramic regenerator made of cordierite, a magnesium aluminum silicate (2MgO·2Al2O3·5SiO2) to capture exhaust heat for automotive applications [Ref. 20.3.3-24]. The cordierite material is also expected to withstand temperatures up to 1200ºC. Monolithic SiC, Si3N4 and SiC/SiC composites are being considered for gas turbine applications at temperatures beyond the capability of nickel based superalloys (alloys discussed above). However, the technical barriers to achieving high performance and large scale use of structural ceramics include inherently low fracture toughness, poor impact resistance and water vapor corrosion at high temperatures and pressures. Use of ceramics for the NGNP IHX would require an extensive, long term material qualification effort in terms of defining heat exchanger designs, characterizing mechanical properties and aging effects, evaluating environmental behavior and standardization of the material used. All of the above would be necessary to codify the material for use in the NGNP IHX design. Based on the available literature and the timeframe for construction of the NGNP, it is unlikely that ceramic materials could be used in the initial IHX of the NGNP. However, testing of prototype ceramic heat exchanger components could be performed in conjunction with the NGNP for potential application in the future and/or replacement of NGNP IHX components, when required.

20.3.3.7.1 Historical Background

The interest in ceramic components for recuperators developed in the early 1970s, when ceramics were being considered for components in engines and turbochargers. The oil crisis had driven up the cost of petroleum-based fuels, and it was thought that the prices would continue to rise. Therefore, the aluminum, steel, and glass industries considered coal as an alternative energy source because it was relatively cheap and abundant. At the same time, they investigated methods for capturing waste heat and returning it to the high-temperature process streams. Researchers found that the waste energy was difficult to recover because the streams (at temperatures up to 1650ºC) fouled surfaces with particulate buildup, and, at the high preheat temperatures (>1100ºC), they were corrosive to metal alloys. Ceramics were investigated because, unlike metal alloys, ceramics have sufficient high-temperature strength and oxidation

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resistance to preheat air up to 1100ºC. However, because the cost of oil dropped in the 1980s, research into ceramic recuperators gradually ceased [Ref. 20.3.3-25].

The early research for the development of ceramics for large, industrial recuperators provides information for the current assessment of ceramic recuperators for microturbines and other applications such as the NGNP IHX. Some of the results of those early investigations are summarized in [Ref. 20.3.3-26]. The materials used and the flow configurations were given, as indicated in the following examples:

GTE used cordierite in a finned-plate design, in which the fins and plates were staked and bonded. The result is a crossflow matrix, although the system becomes counterflow when staged.

Midland-Ross used cordierite in a heat wheel with a segmented-matrix configuration.

Garrett-Air Research (formerly AlliedSignal, now Honeywell) used reaction-bonded Si3N4 (RBSN) and SiC in a tube-in-shell exchanger that is crossflow as a single unit but counterflow when staged.

Solar Turbines, Inc. used sintered SiC for its tube-in-shell design with an axial counterflow configuration. Other materials used were phosphate-bonded SiC, alumina chromia, and magnesia chromia.

The following reports summarize the early high-temperature ceramics research:

Ceramic Heat Recuperators for Industrial Heat Recovery [Ref. 20.3.3-27], which states that cordierite was selected for its “ease of fabrication, relatively low thermal expansion, good thermal shock resistance and good corrosion resistance”

Technology Assessment of Ceramic Joining Applicable to Heat Exchangers [Ref. 20.3.3-28], which investigates joining of ceramics

Economic Application, Design Analysis, and Material Availability for Ceramic Heat Exchangers [Ref. 20.3.3-29], which states that demonstration of performance and durability of ceramic heat exchangers must be shown before they can be considered for industrial production furnaces

Ceramic Heat Exchanger Technology Development [Ref. 20.3.3-30], which describes the use of siliconized SiC materials

Ceramic Heat Exchanger Design Methodology [Ref. 20.3.3-31], which lists the available materials and their vendors (sintered -SiC from Carborundum; reaction-bonded SiC from Carborundum, Coors, Norton, and Refel; sintered SiC and sintered Si3N4 from Kyocera; and nitride-bonded SiC, reaction-bonded Si3N4, and hot-pressed Si3N4 from Norton)

Design Methodology Needs for Fiber-Reinforced Ceramic Heat Exchangers [Ref.3-32], which distinguishes between design of the ceramic material and design with the ceramic material.

It should be noted that most of the companies that investigated these large-size ceramic recuperators are no longer in the field, and several of the companies that manufactured the ceramic materials have also left the business. In both cases, even though new companies replaced the old ones, there are fewer companies in this area now than there were in the 1970s

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and 80s. Because there are fewer companies and because many of the investigators have retired, the availability of experienced researchers who could work on ceramic HXs will be affected.

20.3.3.7.2 Examples of Ceramic Recuperators for Small Turbines

A plate-fin ceramic recuperator for a 60-kW turbogenerator was fabricated as part of the European Advanced Gas Turbine for Automobiles (AGATA) program to develop a gas turbine hybrid vehicle [Ref. 20.3.3-33]. The authors claim that the plate-fin design is flexible and that the fin height and geometry can be varied. Cordierite and SiC were investigated extensively.Cordierite was chosen because its safety coefficient (ratio of the mechanical strength to the induced stress) was higher. Although the mechanical strength of SiC is much higher, the induced thermal stress for cordierite is very low because its Young’s modulus and coefficient of thermal expansion are lower. This recuperator is shown in Figure 20.3.3-21 [Ref. 20.3.3-34].

Figure 20.3.3-21 AGATA Cordierite Plate Type HX

The GTE industrial ceramic recuperator is a product that has survived the period of intensive development and continues to be used today. GTE developed modular crossflow ceramic recuperators (see Figure 20.3.3-22) in three sizes: 10 in (cube), 12-in (cube) and 12x12x18 in, rated at up to 0.4 MWt, respectively, for industrial applications. These recuperators used exhaust gas at ~1320ºC to heat incoming air to 705ºC. The best longevity of the recuperator was obtained when the exhaust gas temperature was less than 1100ºC. Although individual units are crossflow, they can be arranged to simulate counterflow, which would increase their effectiveness. Two points about the GTE recuperators should be noted. The first is that the material of construction is cordierite. The second is that many of these recuperators are still in operation. Based on practical experience, the following observations have theoretical validity [Ref. 20.3.3-25]:

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Conductivity of the material is not important for heat transfer

Pressure drops must be small

Leaks should be constant so they can be designed for

The design for metallic recuperators cannot be translated to ceramic materials

Manifolding to attain counterflow for high effectiveness is difficult

Thermal shock and creep resistance are the determinant properties.

Figure 20.3.3-22 GTE Ceramic Recuperator Matrix

20.3.3.7.3 Materials Selection

In order to fabricate ceramic recuperators, two critical decisions must be made. The first is the selection of the ceramic material and the second is the selection of the construction method. A review of the activities in ceramic recuperation shows that no one material has been used consistently. This is not unexpected, because no one material meets all of the required specifications, which include the following [Ref. 20.3.3-25]:

Low thermal expansion,

High thermal-shock resistance,

Good corrosion and oxidation resistance,

High thermal strength,

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Good creep resistance,

Ease of fabrication, and

Low cost.

During the most active periods of research into ceramic recuperators, the following materials were used: cordierite, Si3N4, and SiC (both reaction-bonded and sintered), nitride-bonded SiC, phosphate-bonded SiC, alumina chromia, and magnesia chromia. Some of these materials are no longer considered for high-temperature operations. Of these materials, silicon nitride and cordierite are likely candidates for further development, but both have their drawbacks. In addition, new materials, such as low-thermal-expansion materials or high-thermal-conductivity carbon foam, developed recently at ORNL, should be evaluated.

Silicon Nitride: Silicon nitride has been investigated most extensively (for at least two decades) and has been found suitable for use at high temperatures. Si3N4 has excellent creep resistance: its creep lifetimes at stresses and temperatures typical of operating conditions have exceeded 10,000 hours, which is superior to those of nickel-based superalloys. However, it is difficult to fabricate and is very expensive. DOE, through the Ceramic Technology Project, has funded several studies to develop Si3N4 with desirable properties for high-temperature structural ceramic applications. Norton produced NT164 Si3N4, Kyocera produced SN282, and AlliedSignal Ceramic Components produced AS800. The material properties of AS800 are typical:

Maximum operating temperature: 1400ºC,

Room-temperature flexural strength: 715 MPa,

Weibull modulus: 20-30,

Fracture toughness: 8 MPa·m1/2,

Thermal conductivity: 65 W/(m·K),

Density: 3.3 g/cm3,

Elastic modulus: 310 GPa, and

The mean coefficient of thermal expansion (CTE) (20-1000ºC): 3.9X10-6/ºC.

Although Si3N4 has excellent material properties, it is very expensive; the powder alone costs nearly $40/lb and its processing is complex. A less-expensive form is reaction-bonded silicon nitride (RBSN), made from cheap Si powder.

Silicon Carbide: Silicon carbide has been investigated most extensively and has been found suitable for use at high temperatures. It has extraordinary resistance to very corrosive environments and is one of a small group of materials that shows little or no effects from exposure to all portions of the S-I cycle. Hot pressed high purity SiC is a very expensive material; however, siliconized SiC is less expensive. The material properties are given below:

Maximum operating temperature: 1650ºC

Room-temperature flexural strength: 446-459 MPa (442MPa at 1000ºC)

Weibull modulus: 12.3

Fracture toughness: 4.6 MPa·m1/2,(Room Temperature); 6.4 MPa·m1/2 (1000ºC)

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Thermal conductivity: 490 W/mK (high purity); 82-90 W/mK (sintered)

Density: 3.14-3.18 g/cm3

Elastic modulus: 406 GPa; 378 GPa (1000ºC)

Mean coefficient of thermal expansion (CTE) (20-1000ºC): 4-4.73X10-6/ºC

Tensile strength (5000C) 280MPa; 240MPa (1000ºC)

Cordierite: Cordierite (2MgO·2Al2O3·5SiO2) was the material used in many of the earlier ceramic recuperators for microturbines (Coors and AGATA). It is the material used in the compact GTE recuperator, which is the only one in industrial application for more than a decade. It is used now as the support for the catalytic combustors in automobiles. Its CTE is low, similar to that of Si3N4, and it has excellent oxidation resistance and low density. Its major benefits are its low cost and relative ease of fabrication. However, it may not be applicable at temperatures beyond 900oC (near its glass transition temperature), although the GTE recuperators apparently operate at higher temperatures. The latter point is a strong argument for investigating this material to find its maximum operating temperature. The properties of this material are quite variable depending on processing and composition.

20.3.3.7.4 Fabrication Methods

Materials selection and fabricability are closely related. Two heat exchanger designs that have been used in the fabrication of compact recuperators for microturbines are the fin-plate and the primary surface types. These are similar in concept to their metallic counterparts, discussed earlier in Section 20.3.3.5. As with metallic heat exchangers, the tube-and-shell method would be unsuitable because the surface area would be excessive. Theoretically, the prime surface approach may seem a better method, because of the poor conductivity of the ceramic fins in the plate-fin approach. However, the plate-fin design may be easier to fabricate and less costly with ceramic materials. [Ref. 20.3.3-25]

The fabrication method has to be amenable to high-volume production. An extrusion process, which is typically difficult in ceramic processing, may have to be developed. However, a continuous-batch operation would suffice. Scale up to high-volume production will follow later.

Honeywell Composites, Inc. (HCI), formerly Lanxide, has been investigating the fabrication of thin-sheet ceramic recuperators based on paper-making technology. The thin-sheet recuperator is made from alumina (Al2O3) particulates in an Al2O3 matrix and is designed for counterflow operation. A prototype recuperator has been fabricated and is being tested. Like cordierite, there is concern about permeability of the material in thin sections.

20.3.3.7.5 NHI Ceramic Heat Exchanger Initiatives

Ceramic heat exchangers are currently being developed through the DOE Nuclear Hydrogen Initiative (NHI) that is being coordinated through the University of Nevada, Las Vegas. The present focus is on process coupling heat exchangers, rather than IHXs.

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Unit cell of offset-finLiquid Si Injectedcomposite plate HX(UC Berkley)

SiC HX Concept(Ceramatec)

Figure 20.3.3-23 Representative NHI Ceramic Heat Exchanger Concepts

Two representative NHI design concepts are illustrated in Figure 20.3.3-23. The SiC heat exchanger concept being developed by Ceramatec comprises a plate-fin architecture that is built up from tape-cast ceramic layers. The liquid silicon injected (LSI) composite plate concept, being developed by the University of California-Berkeley, is created by first producing a carbon fiber reinforced carbon (CFRC) structure and then injecting liquid silicon into the matrix to make the heat exchanger gas tight.

The ongoing NHI heat exchanger development activities will represent a key resource for the evaluation and development of ceramic heat exchangers for the NGNP and commercial applications in the future. It is intended that this program be closely followed.

20.3.3.7.6 Ceramic HX Summary

Currently there are no ceramic or composite materials listed in the ASME Code. The INL and ORNL preformed a study in 2006 to determine a time table for inclusion of these materials in the ASME Code with appropriate ASTM standards. It was determined that, except for nuclear grade graphite, there was inadequate information to determine a timetable for codification of ceramic or composite materials. This issue is currently the subject of discussion in relevant ASME subcommittees on a quarterly basis. Therefore, it is very unlikely that any ceramic or composites (except nuclear graphite) will become a Code material in the foreseeable future. The primary reasons for this are given below:

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Ceramics and composites are custom designed in most cases for specific applications and there are many categories with one ceramic or composite family

The subcategories include multiple ways of powder manufacture, powder consolidation, fiber manufacture, ceramic processing, fabrication of finished components, etc.; there has been little standardization in this area to date

Much of the work being performed is secret or proprietary; this has not facilitated standardization

The structural or critical materials used in a nuclear reactor or an associated critical system has in the past been fabricated from ASME Code materials with standardized validation testing, design procedures and manufacturing methods. Currently, this does not describe ceramics or composites. Significant progress has been made to produce more reliable ceramics and composites with useful mechanical properties; however, the engineering properties of any of the high temperature alloys discussed are far superior to any ceramic or composite in the temperature region of interest. Ceramics and composites are of interest because their mechanical properties remain essentially constant in the temperature regime from 900ºC to 1000ºC or above.These materials are only being considered for the nuclear industry for higher temperatures and extraordinary conditions of corrosion where there are no or few alternative materials and virtually all components that have been fabricated are prototypes or developmental.

It is possible to design a one-of-a-kind system, including heat exchangers, such as the Sulfur Iodine (S-I) hydrogen production process being developed through the Nuclear Hydrogen Initiative (NHI). However, there is little similarity between this program and what would be required to design and manufacture a ceramic IHX as a licensed nuclear component within the NGNP schedule requirements.

The primary issues associated with a ceramic IHX are very high cost (for SiC or Si3N4),lack of standardization, lack of ASME Code acceptance, lack of a design basis, and the scale-up requirements for this application. Therefore, virtually all experts in this area agree that a ceramic or composite IHX is not a viable option for the timeframe of the NGNP initial deployment.

However, the limitations of metallic materials provide significant incentives for the development of ceramic heat exchangers for the IHX, as well as for the Process Coupling Heat Exchanger (PCHX), which poses additional challenges related to the process environment. It is viable to include this type of HX in a prototype testing program that will be discussed later, or to include a ceramic prototype in a side helium stream in the NGNP. This would facilitate the development of a specification, procurement for testing purposes and comparative testing with alloy prototype IHX units in a controlled loop. It is recommended that SiC or Si3N4 be used as the base ceramic for this application. There is a large experience base with Cordierite and this material is relatively inexpensive; however, the material is inferior to SiC or Si3N4 in the area of high temperature properties and, therefore, it may not be worth the long term developmental investment for this application. Si3N4 probably has the best overall properties for this application; however, for combined corrosion resistance and mechanical properties, SiC is superior. While composite materials also appear to have promise, issues associated with fabrication and leakage must be solved before they can be considered viable for this application.

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Based on a private communication with Dave Stinton, ORNL, he believes that it is possible to fabricate a prototype ceramic HX from any of the three ceramics noted using the OxyCube™ process. He also believes that the HX could be fabricated in a scaled up size that would be useful for testing using facilities at ORNL.

20.3.3.8 Codes and Standards Readiness

20.3.3.8.1 Historical Background

Prior to World War II, the design of pressure vessels was based on selecting the thickness such that the maximum design pressure-induced stress in simple geometries was less than one-fifth the ultimate tensile strength. As a war emergency measure, this nominal factor of safety of five was reduced to four. Based on the success of this step, the codes were revised to adopt this lower factor of safety and questions arose as to the practicality of reducing the safety factor further. However, as the design technology including material behavior advanced, concerns were raised as to the need to include additional failure modes in the design of some vessels. These two aspects led to the development of Section III in 1963 and Section VIII Division 2 in 1968. The major conceptual change in these documents was in design, a change so significant that it was termed "Design by Analysis" to distinguish it from the approach previously followed, "Design by Rules." By and large, the safety factors used in Design by Analysis were less conservative than those used in Design by Rules. In summary:

The approach taken by Sections III and VIII Div. 2 is referred to as: Design by Analysis, indicating that it relies on explicit structural analysis to evaluate stress/strain states for design.

The alternative approach of Section I and VIII Div. 1 uses simplified rules and is, therefore, referred to as Design by Rule.

The Design-by-Analysis procedure, as outlined in the Code has the appearance of a linear elastic analysis. In fact the foundation of the methodology is Limit Load Analysis.

The basic intent of the code was to address the requirements for new construction while providing reasonable assurance of reliable operation. Therefore, the requirements were primarily addressed to the manufacturer, although an important role was assigned to the owner/user with respect to defining the operational conditions to be considered by the manufacturer. The means by which the owner/user fulfilled this assigned responsibility was the preparation of a design specification.

A significant ground rule for the Design-by-Analysis procedures was to permit the application of elastic stress analysis techniques, even though practically all of the criteria were developed based on consideration of elastic-plastic failure modes (plastic collapse and necking, fatigue, ratcheting, etc.), because material selection requirements were intended to assure ductile behavior. Although it was intended that the gross behavior of the structure remain elastic, it was recognized that localized plastic deformation was not necessarily harmful. Since most of the failure criteria addressed by the code are for plastic failure, the elastic analysis criteria are usually much more conservative than the elastic-plastic analysis criteria. The objective is to

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provide the designer with the option of satisfying less stringent rules at the expense of more detailed and rigorous analysis. Note that Section III has served as the model for almost all of the nuclear design codes developed in other countries.

With the prospect of the construction of liquid metal fast breeder reactors and high temperature gas-cooled reactors in the U.S. in the late 1960s and early 1970s, a need arose for the development of new Code rules applicable at "high temperatures," where ductile materials undergo thermal creep deformation that can lead to a new set of failure modes (creep rupture, creep-fatigue, creep ratcheting, etc.) not experienced at the low temperatures for which the Section III rules were originally developed. The high-temperature design rules were initially developed as a series of code cases (e.g., Code Case 1331, Code Case 1592, and Code Case N47), which ultimately culminated in Subsection NH of Section III. Subsection NH (Code Case N47) has served as a template for several other code cases for elevated temperature service. Code Case N-499 was developed to address the use of SA-533 Grade B, Class 1 plate and SA-508 Class 3 forgings and their weldments for limited elevated temperature service. Code Case N-201 was developed for core support structures in elevated temperature service. A draft code case for Alloy 617 was in the process of being developed by the Task Group on Very-High Temperature Design before the activity was terminated. The draft Code Case employs a unified constitutive model that does not differentiate between plastic and creep deformation at high temperature (>650°C).

20.3.3.8.2 ASME Board on Nuclear Codes and Standards (BNCS)

Basic information regarding the ASME BNCS and related Code activities is given below:

Charter: To manage all ASME activities related to codes, standards, and accreditation programs directly applicable to nuclear facilities and technology.

Code - A standard which has been adopted by governmental bodies, local, state, or federal, or which is cited in a contractual agreement, and which has the force of law.

Code Case - Documents that clarify the intent of existing Code requirements or provide alternative requirements.

Standard - A set of technical definitions and guidelines developed so that items can be manufactured uniformly and provide for safety and interchangeability.

Guide - A suggested practice, process or method that is not mandatory and may be used as a whole or in part.

The BNCS provides procedural oversight of all nuclear codes and standards activities.The BNCS is composed of:

Standards committees that establish consensus on technical issues

Subcommittees that provide recommendations on technical issues in particular areas such as nuclear components to the standards committee

Subgroups develop proposals in a particular area of specialty such as design. The Subgroups work with various other Working Groups, Technical Groups, and Project Task Groups to develop proposals

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20.3.3.8.3 Basic ASME Code Definitions

Nuclear vessels and piping design criteria are governed by a combination of ASME Code and Nuclear Regulatory Commission (NRC) requirements. The main difference between low-and high-temperature requirements is not so much the effect of temperature, but the effect of time dependency that it introduces. In all other respects, the general design process is identical, and many of the notations used for low-temperature design are carried over to high-temperature applications.

The following six loading categories are defined in the ASME Code (ASME 2004).

Design Loadings: The specified design parameters for the Design Loadings category equal or exceed those of the most severe combination of coincident pressure, temperature and applied loads specified under events that cause Service Level A loadings.

Service Level A Loadings (Normal operation): These are loadings arising from system startup, operation in the design power range, hot standby, and system shutdown.

Service Level B Loadings (Upset conditions): These are deviations from Service Level A loadings that are anticipated to occur at moderate frequency. The events that cause Service Level B loadings include transients which result from any single operator error or control malfunction, transients caused by a fault in a system component requiring its isolation from the system, and transients due to loss of load or power. These events include any abnormal incidents not resulting in a forced outage.

Service Level C Loadings (Emergency conditions): These are deviations from Service Level A loadings that have a low probability of occurrence and would require shutdown for correction of the loadings or repair of damage in the system. The total number of postulated occurrences for such events may not exceed 25.

Level D Loadings (Faulted conditions): These are the combinations of loadings associated with extremely low probability, namely, postulated events whose consequences are such that the integrity and operability of the nuclear energy system may be impaired to the extent that only consideration of public health and safety are involved.

Test Loadings: Pressure loadings that occur during hydrostatic, pneumatic or leak testing. Other types of tests are classified as Service Level A or B loadings.

Safety factors are highest for Level A, followed in decreasing order by Levels B, C, and D.

20.3.3.8.4 Classification of Stresses

The basic premise behind classifying the stresses is that all stresses acting on a component made of ductile materials are not equal as far as the consequences of their presence are concerned. The stresses are characterized in the following three categories: primary stress, secondary stress, and peak stress [Ref. 20.3.3-35]:

Primary stress (Pm, PL, and Pb) is any normal stress or a shear stress developed by an imposed loading which is necessary to satisfy the laws of equilibrium of external and

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internal forces and moments. The basic characteristic of a primary stress is that it is not self-limiting, cannot be relieved by localized plastic deformation, and if not limited, can lead to excessive plastic deformation of the structure. Primary stress is an algebraic sum of general or local primary membrane stress (Pm or PL) and primary bending stress (Pb). Note that local primary membrane stress, PL, includes the general primary membrane stress, Pm. The primary stresses are generally based on linear elastic theory.

Secondary stress (Q) is a normal or a shear stress developed by the constraint of adjacent material or by self-constraint of the structure. The basic characteristic of a secondary stress is that it is self-limiting, because it can be relieved by small-localized plastic deformation that cannot cause large distortion of the structure. Failure from one application of a secondary stress is not expected. Not all deformation-controlled stress can be categorized as secondary stress. The code requires all deformation-controlled stress with high elastic follow-up to be treated as primary stress. Often, membrane components of thermal stresses are categorized as primary.

Peak stress (F) is due to local discontinuities or local thermal stress including the effects of stress concentration. This stress is additive to the primary plus secondary stress. The basic characteristic of a peak stress is that it does not cause any noticeable distortion.The peak stress is objectionable only as a possible source of a fatigue crack or a brittle failure.

In summary:

Primary stresses are intended to represent a sufficient condition to avoid structural failure. According to the bounding theorems of plasticity, ANY stress state, in equilibrium with the load, and not exceeding the yield stress, represents a lower bound on collapse and is therefore safe.

A linear elastic analysis which does not exceed yield satisfies this criterion and, in an age when limit analysis was difficult to implement, a modified elastic route was adopted, based on an initial linear elastic analysis, followed by a procedure referred to as stress “linearization”. These issues are no longer limiting factors today and very powerful analysis techniques are currently available.

The ASME stress classification system is basically sound.

The method of classification provided in the Code may be excessively conservative and, on occasions, wrong and misleading.

A method with less conservatism is needed in order to enter more severe operating environments, as will be expected in future high-temperature applications.

One such method, the Reference Stress technique, already exists and, with some adaptation, could be the basis for an alternative approach to very high temperature design.

This approach is used in the UK and in other parts of Europe, but has not yet been incorporated into the ASME Code

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20.3.3.8.5 ASME Section III, Subsection NB (Elastic Analysis)

In the ASME Code, structural integrity of a component below the creep range is assured by providing design margins against the following failure modes:

Failure by plastic instability or necking,

General structural collapse under a single application of limit load,

Time-independent buckling,

Incremental collapse or ratcheting under cyclic loading,

Fatigue under cyclic loading, and

Fast fracture.

The first two failure modes challenge the ability of the component to resist permanent distortion and/or plastic instability under a single application of the maximum anticipated load; the third failure mode is buckling of a slender component due to compressive loading; the next two failure modes challenge the ability of the component to survive a succession of the same and/or different loads; and the final failure mode challenges the defect tolerance of the component. Rules are given in the code to protect against these failure modes using either elastic or plastic analysis techniques.

The ASME Code requires that for normal operation and upset conditions (Service Level A and B loadings):

Pm Sm, where Sm is the minimum criterion among time independent stress components; Sm = minimum {1/3 Su or 2/3 Sy} where Su and Sy are the ultimate tensile and yield strengths, respectively at a given temperature

For upset conditions (Level B loading), the value of Sm, above, may be increased by 10%. For emergency conditions (Service Level C loading), the allowable general primary membrane stress intensity is:

Pm max 1.2 Sm or Sy

For faulted conditions (Service Level D loading), the allowable general primary membrane stress intensity is:

Pm 0.7 Su or 2.4 Sm

The ASME Code requires that for normal operation and upset conditions (Service Levels A and B loadings):

PL + Pb KSm where K 1.5 and represents the ratio between the loads to cause fully plastic section and initial yielding in the extreme fiber of the section. For shells and solid sections, K = 1.5.

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For upset conditions (Level B loadings), the value of Sm may be increased by 10%. For emergency conditions (Service Level C loading), the allowable local primary membrane plus bending stress intensity is:

PL + Pb KSy or 1.2KSm

For faulted conditions (Service Level D loading), the allowable local primary membrane plus bending stress intensity is:

PL + Pb <1.05Su or 3.6 Sm

A more comprehensive review of these issues is given in [Ref. 20.3.3-35].

20.3.3.8.6 ASME Section III, Subsection NH (Elastic/Inelastic Analysis)

Subsection NH of ASME B&PV Code, Section III, provides high-temperature design rules for construction of Class 1 components having metal temperatures exceeding those covered by the rules and stress limits of Subsection NB and Tables 2A, 2B, and 4 of Section II, Part D, Subpart 1. Table 20.3.3-9 lists the materials included in Subsection NH along with the maximum temperatures permitted.

Table 20.3.3-9 Subsection NH Materials and Maximum Allowable Times and

Temperatures

Temperature (°C)a,c

MaterialPrimary Stress Limits and Ratcheting Rules

Fatigue Curves

304 stainless steel 816 704

316 stainless steel 816 704

2 1/4 Cr – 1 Mo steel 593b 593

Alloy 800 H 760 760

Modified 9 Cr – 1Mo steel (Grade 91)

593b 538

a. Allowable stresses extend to 300,000 h (34 years) unless otherwise noted.

b. Temperatures up to 649 °C are allowed for not more than 1000 h.

c. Alloy 718 is allowed up to a maximum temperature of 550 °C.

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The first step in design for elevated temperature is to design the component for low-temperature operation. The first few steps in the design process are, therefore, identical with those used in low-temperature applications. Operation at elevated temperature introduces time-dependent failure modes. Thus, in addition to the six time-independent failure modes addressed previously, the following six time-dependent failure modes are considered in the high-temperature design:

Creep rupture under sustained primary loading,

Excessive creep deformation under sustained primary loading,

Cyclic creep ratcheting due to steady primary and cyclic secondary loading,

Creep-fatigue due to cyclic primary, secondary, and peak stresses,

Creep crack growth and non-ductile fracture, and

Creep buckling.

Rules are given in Subsection NH to protect against these failure modes using elastic and, in some cases, either elastic or elastic-plastic analysis techniques. To carry out high-temperature design, the following mechanical properties as functions of temperature are needed, from which the design allowables are derived after applying appropriate safety factors:

Modulus of elasticity and Poisson's ratio (average),

Yield strength Sy (average and minimum),

Ultimate tensile strength Su (average and minimum),

Stress-strain curves (average and minimum),

Stress vs. creep rupture time for base metals and their weldments (average and minimum),

Stress vs. time to 1% total strain (average),

Stress vs. time to onset of tertiary creep (minimum),

Constitutive equations for conducting time- and temperature-dependent stress-strain analysis (average),

Isochronous stress-strain curves (average),

Continuously cycling fatigue life as a function of strain range at a fast strain rate (average), and

Creep-fatigue cyclic life involving cycles with various strain ranges and hold times (average).

Any loss or change in mechanical properties caused by thermal aging, decarburization, etc., with long-term high-temperature exposure in an environment should also be included in the database. The stress-strain curves and constitutive equations, included above, are needed for conducting inelastic stress-strain analyses. The rest of the items listed above are required for satisfying elastic as well as inelastic analysis limits.

In addition to the time-independent Sm, the code introduces a temperature and time-dependent quantity St to account for creep effects. For each specific time t and temperature T, St for the base metal is defined as the lesser of the following three stresses:

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100% of the average stress required to obtain a total (elastic, plastic, primary creep, and secondary creep) strain of 1%;

80% of the minimum stress to cause initiation of tertiary creep; and

67% of the minimum stress to cause rupture.

A basic primary stress limit for high temperatures is Smt, which is the lesser of Sm and St, and is a function of both time and temperature. Note that the definition of St assumes that the material has a classical creep curve. However, some nickel alloys exhibit a non-classical creep curve with no clear primary creep or secondary creep regime. The above definition of St has to be revised for these materials. St and Sm curves are needed as a function of temperature for the determination of Smt. As shown in Figure 20.3.3-24, St is the time dependent stress intensity (1 hour to 300,000 hours), plotted versus temperature; Sm is the time independent stress intensity; Smt is the allowable stress intensity which is the lesser value of St or Sm for a specific temperature; therefore Smt is time dependent. Tensile and creep data are required to produce Sm and St Curves.

0

25

50

75

100

125

150

400 500 600 700 800 900 1000

ST

RE

SS

, M

Pa

TEMPERATURE, C

Sts&TSmt040825NGNPTestPlanORNL / W.Ren

1 h

10 h

30 h

100 h

300 h

3 x 105 h

105 h

3 x 104 h

104 h

3 x 103 h

103 h

Sm

Figure 20.3.3-24 Typical Curves for Sm and St

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20.3.3.8.7 ASME Section III, Subsection NH Design Issues

ASME Section III, Subsection NH applies above the temperature limits for Subsection NB allowable stresses [Ref. 20.3.3-36]. Subsection NB applies above temperature limits if creep effects are demonstrated to be not significant. As noted above, only 304 & 316 stainless steels, Alloy 800H, 2-1/4Cr-1Mo alloy pressure vessel steel and, recently, 9Cr-1Mo-V alloy pressure vessel steel are approved pressure boundary materials under NH. Alloy 718 is approved for bolting.

The ASME Subsection NH design condition evaluation is the same as for ASME Section VIII, Div 1, and with the same allowables. The ASME Subsection NH service condition allowable stress criteria are the same as ASME Subsection NB for time-independent Sm, but different and more conservative than ASME Section VIII, Div 1 for the time-dependent allowable, St. Evaluation of design conditions and all service conditions except Level D are based on a linear elastic material model. Time fraction summations are used to evaluate different stress, time and temperature conditions with time fractions summed over all service conditions.Time fraction is time in a specific condition divided by allowable time at that condition. Weld strength reduction factors are provided for permitted weld metal and properties, with the analysis based on parent metal properties. Strain limits and creep-fatigue damage rules can be satisfied using either elastic or inelastic analysis methods. Elastic analysis rules, originally envisioned as a simpler, more conservative and less costly screening method to satisfy strain limits and creep-fatigue, are actually considerably more complex than analogous ‘low” temperature rules in Subsection NB. Inelastic rules envisioned as a more costly and time consuming “gold standard” are conceptually simple but require sophisticated modeling of material behavior in the creep regime. Requirements for material modeling are only addressed in general terms. Strain limits, creep-fatigue and weld criteria are summarized below:

Strain Limits

Accumulated averaged membrane strain, 1%; membrane plus linearized bending strain, 2%; total strain, 5% Based on collective judgment and numerous rationale; no rigorous, failure-related basis

Strain Limits Using Elastic Analysis

Based on elastic section of Bree Diagram; Simplest to use but most conservativeASME T-1324, Test No. A-3 provides criteria for negligible creep with time fraction summation of creep damage less than 0.1, based on sustained stress 1.5 times minimum Sy and accumulated strain less than 0.2% based on sustained stress 1.25 times minimum Sy. This requires maximum primary stress over component lifetime to be considered with maximum secondary stress range over component lifetime.

Strain Limits Using Simplified Inelastic Analysis

Based on extension of Bree analysis by O’Donnell & Porowski and, later, Sartory Key is elastic core stress limit and subsequent deformation Requires pressure induced membrane and bending and thermal induced membrane stresses to be classified as primary stresses

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Requires maximum primary stress over lifetime be considered with maximum secondary stress range over whole life More complex than analogous Subsection NB primary plus secondary stress limits

Creep-Fatigue (see Figure 20.3.3-25)-Major source of conservatism in NH

Criteria: (n/Nd) + ( t/Td) D where n is the number of cycles of a given strain range; Nd is the allowable number of cycles at that strain range; t is time at a stress level calculated from average properties; Td is the allowable time at the calculated stress level divided by a factor, K’ = 0.67, as determined from plot of minimum stress to rupture versus time to rupture and D is a damage factor to account for combined effects of creep and fatigue. The limits of D for selected materials are given in Figure 20.3.3-25.Rationale for conservatisms: K’ = 0.67 is based on Eddystone piping failure and component test results; D for 9Cr-Mo-V due in part to environmental effects and in part to evaluation methodology and expectation that this would be revisited if material was used in practice. Result: Wall thickness may be limited by creep-fatigue rather than load

controlled stress criteria

Welds

Weld strength reduction factors Strain limits half that of parent material Creep-fatigue limits: Nd, allowable number of cycles reduced by factor of two and Minimum parent metal creep rupture strength reduced by weld strength reduction factorWeld geometry: Worst case weld geometry is used in the analysis; geometry must be confirmed by inspection

ASME Section III, Subsection NH issues are summarized below:

Currently Subsection NH includes a very limited set of materials

Subsection NH has never been used for design of a Section III structure

Subsection NH rules are very conservative and difficult to use

Subsection NH is only applicable at temperatures up to 760ºC

Subsection NH has never been accepted by the NRC; the NRC has taken a neutral position until there is an applicable nuclear application

ASME Section III, Subsection NB is easier to use and it is better to maintain the Class 1 boundary below the creep range, if possible

Subsection NH is currently not useful for design of the IHX structures

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Figure 20.3.3-25 ASME Figure 20.3.T-1420-2 Creep-Fatigue Damage Envelope

20.3.3.8.8 ASME Section VIII Issues

ASME Section VIII Div 1 allows potentially useful materials for construction of the IHX (Alloy 800H-982ºC, maximum; Alloy 617- 982ºC, maximum; Hastelloy X- 898ºC, maximum and Alloy 230- 982ºC, maximum); however, Section VIII, Div 2 does not allow the use of these materials. Section VIII, Div 1 and Div 2 design rules are relatively easy to apply for tube and shell HXs and associated pressure vessels but not easy to apply for a plate type IHX. Basic design equations for plate type HXs are contained in Compact Heat Exchangers [Ref. 20.3.3-37] and Fundamentals of Heat Exchanger Design [Ref. 20.3.3-38]. ASME Section VIII does not contain specific design rules directly applicable to plate type HXs. It is not clear what design rules are currently being used to design Heatric plate type PCHE units, but the rules do not appear to be ASME-based.

Fatigue, environmental and aging issues are not currently addressed adequately in the ASME Code. The alloys listed and the maximum design temperatures in Section VIII are potentially useful for VHTR IHX applications; however, it is unlikely that the NRC would support IHX design and fabrication using Section VIII. Therefore, because metallic alloys that

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could potentially be used to construct the IHX are not currently a part of the ASME Nuclear Code, Section III, it is envisioned that a significant effort will be required to resolve this issue because a reliable database potentially useful for a code case based on three well-documented heats of material is not available.

Also, there is no existing ASME Section III design basis for either a conventional tube and shell IHX or less-conventional plate-type IHX. The most expedient approach for the NGNP IHX appears to be development of an application-specific design basis and submittal of a Section III code case associated with Subsection NH. A significant effort will also be required to resolve this issue because an openly available design basis is not available in a format suitable for a code case. Therefore, if a plate-type IHX is selected, testing of prototype IHX units would be needed to support the code case design basis for the specific IHX design selected.

20.3.3.8.9 DOE Initiative to Address ASME Code Issues

20.3.3.8.9.1 Funded Tasks

A three-year collaboration has been established between DOE and ASME that proposes to address twelve topics in support of an industrial stakeholder’s application for licensing of the NGNP [Ref. 20.3.3-2]. Efforts to address the first five tasks are currently underway. The majority of these tasks are relevant to action items within ASME Section III, Subsection NH. The nature of the topics inherently includes significant overlap and, in some cases, parallel activities on the same issue. These tasks are summarized below.

Task 1: Verification of Allowable Stresses

Stress allowables for Alloy 800H include data for Alloy 800, and differences exist for stress allowables found in Subsection NH and RCC-MR for Grade 91. There are also discrepancies between material properties as implemented in allowable stress values in Subsection NH and Section II, Part D which should be in agreement. The review of stress allowables for base metal and weldments of Alloy 800H and extension of time-dependent allowables to 900°C (which would require data at least 25°C above the temperature at which allowables are set in order to achieve more reliable extrapolation to longer times) are desired, if possible. Similarly, review of stress allowables for Grade 91 Steel is desired.

The task will require formal access to and use rights of the various materials databases. The original database needs to be assembled and reviewed, including methods used to set the time-dependent allowables. Comparison of European and Japanese databases and the methods and procedures used by these sources to set allowable stresses are needed to provide guidance and comparison on how to set allowable stresses for ASME Section III, Subsection NH. For Alloy 800H, the U.S. database needs to include existing data produced up to 925°C, including both creep and stress rupture data. An updated compilation of the creep and rupture data for Grade 91 needs to be assembled, especially for up to 300 mm thick plate, forgings, and heavy wall piping. Consideration of post-weld heat-treatment (PWHT) effects needs to be made. Assessment of alternate procedures for describing creep and stress-rupture for conditions of concern to the NGNP, namely 60 year plant life, is also required; procedures developed by the

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Pressure Vessel Research Council need to be considered as well. The current allowables need to be compared to the results of the reassessment, and a recommended course of action made with respect to ASME Section II-Part D and III-NH.

Task 2: Regulatory Safety Issues in Structural Design Criteria for ASME Section III,

Subsection NH

The NRC licensing review of the Clinch River Breeder Reactor Plant (CRBRP) in the 1970’s and 1980’s identified a number of concerns, including but not limited to weldment safety evaluation, notch weakening and creep-fatigue evaluation. The major fundamental regulatory safety need was improvement of the criteria to prevent creep cracking. The need to build confidence in the regulatory community that the resulting designs will have adequate safety margins is critical. Compilation and storage of reports describing confirmatory program plans that were jointly developed by the NRC and the CRBRP are needed. A review of all the safety issues relevant to Subsection NH is required, including the generation of a historical record that includes a detailed description of how Subsection NH currently addresses these issues or not; further, identification of additional safety concerns within NH for application to very high temperature service is needed. The review will serve as a foundation to initiate communications with the NRC on these issues, and facilitate future consultation with the NRC in improving, developing, and confirming design and fabrication procedures, strain limits and material design curves.

Task 3: Improvement of ASME Section III, Subsection NH Rules for Negligible Creep and

Creep-Fatigue of Grade 91 Steel

Significant differences in prediction of creep strain under monotonic loading exist between Subsection NH and RCC-MR. These differences are critical in satisfying the insignificant creep criteria and are likely due to extrapolation of data from 500-600ºC to lower temperatures applicable to the NGNP RPV, 370-450ºC. The current approaches available to define negligible creep need to be reviewed and their applicability verified for use with Grade 91 steel. Material data available in France and the U.S are needed. The methodology, data and additional tests required to support the definition of negligible creep conditions for Grade 91 steel need to be identified.

The damage envelopes for creep-fatigue are significantly different for Grade 91 steel in Subsection NH and RCC-MR codes. The differences have yet to be explained by scatter in data, variation between heats, whether the damage envelope is procedure dependent (e.g., definition of stress and creep damage during hold times), material softening, or other yet unidentified causes.Hence, a critical comparison of ASME Section III, Subsection NH and RCC-MR creep-fatigue procedures is needed.

Comparisons are desired on the basis of experimental test results available from Japan, France and the U.S.; particular attention is required in the definition of safety factors and creep-fatigue damage envelope procedures. Assessment of whether or not the material data presently available in nuclear codes are thought to be sufficient and valid is required, including

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recommended improvements to existing procedures and definition of a test program to validate the improved procedures.

Task 4: Updating of ASME Nuclear Code Case N-201

The scope of Code Case N-201 needs to be expanded to include materials with higher allowable temperatures, extend the temperature limits of current materials if possible, and to confirm whether the design methodology used is acceptable for design of core support structure components at the appropriate elevated temperatures. The maximum operating temperatures required for High-Temperature Gas-Cooled Reactor (HTGR) metallic core support structures must be identified in a review of data made available by AREVA, GA, PBMR, DOE and other available sources. Operating parameters including but not limited to temperature, pressure, time and environment need to be defined. Candidate materials need to be identified and prioritized for use as metallic core support structures within the defined operating parameters. The design methodology used, which is primarily based on ASME Section III, Subsection NH, needs to be critically reviewed for application to Generation IV reactors, specifically the NGNP.Recommendations for inclusion of new materials or extension of times and temperatures for current materials are required. If necessary, recommended changes and/or additions to design methodologies should be made. Note that Task 7 (not funded) closely parallels this portion of Task 4 - namely the evaluation of Subsection NH and Simplified Methods. Gap analysis on material data needs is required; including the definition of supplemental testing required to support determination of material design curves (e.g., creep rupture, creep-fatigue, etc.).

Task 5: Creep-Fatigue Procedures for Grade 91 Steel and Hastelloy XR

Tasks 3 and 7 include intentional parallel activity in evaluation of creep-fatigue procedures for Grade 91 (Task 3) and Alloys 617 and 230 (Task 7). The intent in this task is to compare procedures used on two different classes of alloys, and to develop modified or new procedures for application to universal creep-fatigue modeling and alloy specific procedures.The task will require that formal access to and use rights of the various materials databases be secured, followed by an evaluation of the state of existing data to determine if more data are necessary. Candidate database sources include Grade 91 steel data generated for the Japanese demonstration fast breeder reactor and Hastelloy XR used in the HTTR. Recently, agreement has been obtained between the ASME and JAEA to transfer the Hastelloy XR database.

Creep-fatigue criteria need to be summarized based on existing international nuclear codes, e.g. Subsection NH, RCC-MR, and Monju Design Codes. A comparison of creep-fatigue damage evaluation procedures is required, including assessment methods of strain range, initial stress and relaxation behavior, formulation of creep damage, strain rate and hold time effects, methods used in partitioning plastic, elastic, and creep strain, environment effects, and wave shape effects. A recommended testing program to generate required supplemental data needs and model verification are needed.

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20.3.3.8.9.2 Unfunded Tasks

The seven task areas noted below are currently unfunded:

Graphite and ceramic code development (Task 6)

NH evaluation and simplified methods development (Task 7)

Identification of testing needed to validate elevated temperature Section III, Subsection NH design procedures in support of the NGNP (Task 8)

Address the lack of environmental and neutron fluence effects associated with ASME Section III (Task 9)

ASME Code rules for the IHX (Task 10)

Flaw assessment and leak before break ASME Section III rules in support of the NGNP (Task 11)

Improved NDE methods (Task 12)

20.3.3.8.9.3 Project Organization

The current project organization is given in Figure 20.3.3-26.

Gen IV Materials Project Organization

ASMECode Committees

(C&S Connect)

Technical AdvisorsSubcontracted Code Experts

Task InvestigatorsSubcontracted Subject Matter Experts

Project ManagerJames Ramirez - ASME Staff

DOEProject Officer

John Yankeelov

Steering CommitteeASME C&S

VHTR Vendors, UtilitiesDOE, NRC

Figure 20.3.3-26 Current ASME/DOE Project Organization

The primary affiliated organizations for each of the funded tasks are given below:

Task 1: University of Dayton Research Institute

Task 2- O’Donnell Engineering

Task 3- AREVA-Framatome ANP

Task 4- Westinghouse Electric

Task 5- Japan Atomic Energy Agency

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The primary tasks that are of interest to the Code issues associated with the NGNP IHX are: Tasks 1, 2, 4 and 5 (funded tasks) and Tasks 7, 8, 9 and 10 (unfunded tasks).

20.3.3.8.10 ASME Draft Code Case for Alloy 617

A request to the ASME to establish high temperature design rules was made in the 1980s from the DOE and one of its contractors [Ref. 20.3.3-35]. Materials of potential interest included Alloys 800H, Hastelloy X and Alloy 617. An ad hoc task force of the ASME was established in 1983 to address the design of reactors operating at very high temperatures. The task force was organized under the Subgroup on Elevated Temperature Design of the Subcommittee on Design. The task group completed the draft code case in 1989 and submitted it to the subgroup which later approved the code case. No further work was done on the code case due to a lack of interest from the DOE and its contractor. The code case was patterned after Code Case N-47 and was limited to Alloy 617. The draft code case focused on this alloy because it was a leading materials candidate for high temperature designers and a significant high temperature data base was available with this alloy.

The code case focused on the failure modes addressed in Section III, Subsections NB and NH including non-ductile fracture. Non-ductile fracture was included because it was known that Alloy 617 showed a significant loss of fracture toughness after long term exposure to high temperatures (aging). Some of the design rules given in the draft code case were different from those given in Subsections NB and NH, and included somewhat unique behavior characteristics including: (1) a lack of a clear distinction between time dependent and time independent behavior, (2) high dependence of flow stress on strain rate, (3) softening as a function of time, temperature and strain. The draft code case specified that inelastic analysis above 649ºC must be based on unified constitutive equations which do not distinguish between time independent plasticity and time dependent creep. The draft code case prohibits cold worked material because Alloy 617 recrystallizes following high temperature exposure if it is in the cold worked condition.

Alloy 617 bolting is excluded from the draft code case, due to the loss of fracture toughness following aging.

The draft code case is based on a limited data base and minimal service experience. It was also determined following the publication of Shah, et al, 2003 that the draft code case for Alloy 617 had other deficiencies that were not easily resolved. These deficiencies included [Ref. 20.3.3-17]:

Lack of test data that approach the low stresses and long durations required for the NGNP. The current data base was obtained by the application of higher stresses and these data would require significant extrapolation for an IHX-type component for the NGNP

The existing database primarily uses power law creep as the deformation mechanism. There is uncertainty about whether this mechanism remains dominant at the significantly lower stresses and very long times envisioned for the IHX

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If a different deformation mechanism dominates at lower stresses, extrapolation of power law creep data to lower stresses could predict non-conservative (lower) creep rates by several orders of magnitude

The existing data base was obtained primarily on relatively coarse grain material because this type of material favors greater creep resistance; however, if a compact plate type IHX is used for the NGNP a smaller grain size will be required because of fabrication using very thin sheets formed in a stack

Therefore, the basis of much of the draft code case data (isochronous stress-strain curves) will need to be reevaluated using small grain material. Testing should also include creep fatigue testing of weldments (including diffusion bond joints) and environmental effects. The grain size (GS) issue applies to the PCHE. Input from Heatric to MIT regarding a proposed experimental Alloy 617 heat exchanger provides some insights in this regard. For a plate thickness of 0.9mm, Heatric recommended a GS of ASTM 8 or finer. ASTM 8 has an average GS of 0.0254 mm which equals an average of 35 grains across the 0.9 mm thickness.

The current reference for Alloy 617 plate is ASTM GS 0 (0.405 mm) to ASTM GS 3 (0.143 mm). The range of grain size in the known Alloy 617 data base is 0.1 mm to 1 mm, based on references that actually reported the GS. It is a matter of opinion how large the GS should be for 0.9mm thick material but ASTM 6 (0.051mm) with 18 grains across the thickness or finer should probably be specified in order to mitigate crack propagation across the section. The Heatric guideline may be a little conservative, but it is indicative of their opinion on this issue.

20.3.3.8.11 Summary and Recommendations

Metal alloys that could potentially be used to construct the IHX (except for Alloy 800H) are not currently a part of the ASME Nuclear Code, Section III. A significant effort will be required to resolve this issue because a reliable database potentially useful for a code case based on three well-documented heats of material is not available. There is no existing ASME Code basis (Section III or other) for the application of ceramics in pressure boundary applications. There is no existing ASME Section III design basis for either a conventional tube-and-shell IHX or less-conventional plate-type IHX. The most expedient approach for the NGNP IHX appears to be development of an application-specific design basis and submittal of a Section III code case associated with Subsection NH. A significant effort will also be required to resolve this issue, because an openly available design basis is not available in a format suitable for a code case. If a plate-type IHX is selected, testing of prototype IHX units would be needed to support the code case design basis for the specific IHX design selected.

The IHX for the NGNP should be contained in a Class 1 pressure boundary from an ASME Code consideration and to minimize pressure-induced stresses in the unit, because of the low metallic materials margin at 900-950ºC. A pressure boundary will be needed if a plate type HX is used, which under current rules is not a Code vessel. The pressure boundary size would be greatly reduced if a plate-type HX unit is used for the NGNP IHX. The pressure vessel(s) should probably be designed using ASME Section III, Subsection NB design rules (no creep) and should be insulated and cooled as required.

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The following recommendations are made:

It is recommended that a plate-type HX development program be pursued for the NGNP IHX in conjunction with an appropriate design and materials development program, which will be discussed later in this report.

It is recommended that revision of Subsection NH be a longer-term target; however, it is recognized that submittal of a code case of the type envisioned would have a significant impact on Subsection NH.

It is recommended that a shorter-term target be focused on a code case specifically designed to provide an ASME design and fabrication material basis for the NGNP IHX.

It is recommended that an R&D program be performed to obtain adequate test data to support the code case for the IHX alloy selected

It is recommended that the Alloy 617 draft code case submitted in 1992 not be revised and updated

It is recommended that one or more small (100-200kw) prototype plate-type HX units, including a ceramic unit, be procured and tested at an appropriate testing facility. A potential testing program is contained in Kesseli et al, 2006.

It is recommended that detailed finite element analysis be performed on a plate-type HX grid for use as a design and evaluation tool. Some work in this area has been performed in the past; however, it is either not comprehensive or is proprietary (Heatric; Velocys; Brayton Engineering)

20.3.3.9 Design Data Needs and R&D Program

20.3.3.9.1 Introduction

Design Data Needs (DDNs) for the IHX and associated materials can be generally identified with the following categories:

Material properties data relevant to the selected alloy (presumably either Alloy 617CCA or 230, depending on the high temperature strength and creep requirements for the IHX design). This data would support the materials part of the directed IHX ASME Section III Code Case

Design methods and design basis information, based on detailed analysis, that would support the design part of the directed Code Case

Verification of IHX performance and structural adequacy. Fulfillment of this DDN is likely to require testing of prototype IHX units that are procured following detailed discussions and a detailed procurement specification for the IHX design selected (presumably a plate-type HX concept)

IHX/materials DDNs and the R&D efforts to resolve them will be overviewed in this section of the report, based on the assumption that the prior recommendations are implemented and that Alloy 617 CCA or Alloy 230 is selected as the IHX fabrication material. Only a

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summary plan will be presented because a refined plan is dependent on several factors that will be discussed. A refined R&D plan can only be established following meetings with selected ASME Code experts. If a conventional tube and shell design is selected for the IHX, a design basis in ASME Section VIII, Div 1 has been established. However, ASME Code experts would need to evaluate the applicability of the Section VIII alloys and the specific design basis for the NGNP IHX.

If a plate-type IHX design is selected for the IHX, then the ASME experts would need to recommend the best approach that could used to implement a new design basis that is not currently a part of the ASME Code and recommend laboratory testing that would be needed to support the IHX alloy selected. These steps would only be partially effective until a final decision on IHX design and alloy is made. These decisions are needed before detailed Code planning and laboratory testing can be finalized.

The intent of Task 10 of the DOE/ASME initiative is to initiate these discussions; however, the implementation of Task 10 has been delayed due to funding issues. Prior to the selection of the reactor design and primary component suppliers, the intent of Task 10 is to:

Determine how and where within ASME codes and standards the IHX and similar components should be addressed

Address many technical questions to determine how the function of these components affects the plant from an engineering and safety perspective

Consider all aspects of the potential IHX designs that could be used including materials, design fabrication, examination, testing, overpressure protection and in-service inspections that would be a part of the design or operation of the IHX

Consider the design and location of the pressure boundary

Discuss design criteria, including methods for evaluation of cyclic life, construction codes of record and designated pressure boundaries, qualification of materials and fabrication techniques for the intended service and environmental effects

Following the selection of the reactor design and primary component suppliers, the intent of Task 10 is to:

Perform an evaluation of IHX design approaches with respect to past experience, including scoping analysis to identify critical design configurations and loading conditions

Recommend changes or additions to current construction codes including ASME Section III, Subsection NB, NC, ND and NH, including their supporting code cases and Section VIII, Div 1 and 2

Therefore, there are two approaches that could be used to address the issues noted:

Option 1- Jumpstart the process by establishing a study group to perform at least some of the activities noted above in a directed manner based on the actual design and materials decisions that have been made for the IHX and related containment systems

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Option 2 - Fund Task 10 based on ASME cost requirements and proceed down the path with the Task 10 study group, noted above

A primary issue for determining the path to follow is the time requirements for the initiation of final procurement of the IHX and related hardware, which is established as the end of fiscal year 2012. This allows about 6 years for completing this work, submitting a new code case and obtaining ASME approval of the code case. It is estimated that drafting and approval of the code case would take about 3 years after all decisions, additional data generation and analyses have been completed. This leaves about 3 years to finish the study group activities.This seems like a lot of time; however, considering the scope of the activities to be considered, three years is considered marginal. The following recommendations are made:

It is recommended that Option 1 be implemented with appropriate ASME Code Committee representation and funded by the NGNP conceptual design contractors

It is recommended that initial discussions in support of Option 1 be held with Bob Jetter ([email protected]), Chairman, ASME Section III, Subsection NH and Jim Ramirez ([email protected]), ASME Task Group Manager. The purpose of these initial discussions would be to discuss more directed planning of the IHX issue to reduce the time required for the study group, draft a revised statement of intent for the study group and discuss potential Code experts that could be contracted to staff the study group.Based on a personal communication with Jim Ramirez, this appears to be an appropriate path forward.

20.3.3.9.2 Design Data Needs for Materials

Materials-related DDNs comprise those required to support a directed code case for the NGNP IHX material. All relevant Alloy 617 or Alloy 230 (assuming one of these alloys is selected) data should be collected or obtained from sources world-wide and evaluated. The evaluation should center on the quality of the data and whether the data is available in raw form. The data collected should include tensile test data, isochronous test data, low cycle fatigue test data, creep test data, environmental test data in impure He and aging data at various temperatures and times of interest to the IHX. It is recommended that the format established by ORNL for the Generation IV Materials Handbook [Ref. 20.3.3-39] be used. After the data has been collected and analyzed, a detailed R&D program can be established to obtain the missing information for a code case. In general, the R&D program is expected to include some or all of the following elements. For ASME code acceptance the following should be obtained from each of three heats of material.

20.3.3.9.2.1 Thermal Physical & Mechanical Properties DDNs

Thermal Physical Properties Thermal conductivity Coefficient of thermal expansion Chemical composition

Mechanical Properties Elastic constants (E, G, )

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Tensile stress-strain-time curves in strain control; temperature ranges to be determined per grade/alloy; various strain rates to be determined Yield & Ultimate Strength vs. temperature & strain rate; generation of Sy and Su at various temperature up to 1000ºC Uniform and total elongation vs. temperature & strain Fatigue Strength; Strain control, constant strain rate; LCF, various temperatures; Stress-strain-time history record of tests for cycles; Strain rate effect Creep Strength (some tests will continue for up to 100,000 hours and these results will not be a part of the original code case); Constant load or stress; Time to rupture; Strain at rupture; Stress-strain-time data, including behavior upon loading, primary, secondary, and tertiary deformation; generation of St, Sm, Smt at various times and temperatures up to 1000ºC Creep-Fatigue Strength; Strain controlled; Constant strain rate (except hold portion); Variation of hold-time effect; Variation of strain rate effect, effect of tensile vs.compressive vs. tension-compression hold; Stress-strain-time history record of tests for cycles at various temperatures up to 1000ºCFracture Toughness at various temperatures up to 1000ºC Creep Crack Growth at various temperatures up to 1000ºC Fatigue Crack Growth at various temperatures up to 1000ºC

20.3.3.9.2.2 Weldability DDNs

The ability to weld Alloys 617 and 230 without unacceptable loss of strength and corrosion resistance needs to be developed and demonstrated. Adjust and select several weld filler materials to match strength with base metal.

Fusion weld plate material

Diffusion bond sheet material

Conduct short term mechanical properties testing (tensile, creep, Charpy impact) at various temperatures up to 1000ºC on:

As-welded material Aged in air (1,000 and 10,000 hours)Aged in impure He (1,000 and 10,000 hours)

Conduct optical, SEM, and TEM examination of material to evaluate microstructure, strength, and failure modes

Evaluate effect of grain size on above

20.3.3.9.2.3 Aging of Ni-based Alloys DDNs

Aging effects on the short and long term properties at various temperatures up to 1000ºC Short term properties: tensile, Charpy impact, hardness Long term properties: fatigue, creep, creep-fatigueMicrostructural stability & evaluation

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20.3.3.9.2.4 Exposure to Impure He at Elevated Temperatures up to 1000ºC DDNs

Corrosion effects on the short and long term properties

Short term properties: tensile, Charpy impact

Long term properties: fatigue, creep, creep-fatigue

Microstructural stability & evaluation

20.3.3.9.2.5 Grain Size Effects DDNs

It is important to identify the creep deformation mechanism that dominates at the low stress levels and long lifetimes of the IHX. An initial testing plan would involve a series of applied stresses that are likely to produce creep strains in each of the deformation mechanism regimes noted in Figure 20.3.3-27 and Figure 20.3.3-28 [Ref. 20.3.3-17].

These figures show possible test points for Alloy 617 at 850ºC and 950ºC; tests on Alloy 230 would be similar. In each case, three stresses are selected on each side of the mechanism transition point for material with a nominal grain size of 100 microns (solid squares). The lower stresses will likely produce creep rates consistent with Nabarro Herring creep while the higher stresses will be dominated by power law creep. By plotting the measured creep rates on a log-log scale (as seen in the figures) it is expected that the transition point will be easily identified as a change in slope between the two regimes. Tests at 900ºC would also be needed. By plotting lines of constant stress as a function of times and temperature, it will be possible to derive parameters for common creep extrapolation techniques. Separate parameters will be derived for each deformation mechanism, giving a physical basis for the extrapolation that is related to the material microstructure. These procedures may need to be varied to produce the desired results.

20.3.3.9.3 Design Basis Information DDNs

The data obtained from laboratory testing or prior data generation will be used to generate specific code-related information. It is assumed that a detailed finite element analysis (FEA) of the IHX will be required to obtain a portion of the design basis information. Further development of analysis methods may be required to support such an analysis. The remaining information for the code case will be obtained from existing design equations and models developed for the plate type IHX (if selected). If a tube and shell IHX is selected, it is assumed that only minimal design basis information (except that derived from lab testing on the alloy selected) will be required because of the existing design basis contained in ASME Section VIII; however, without further discussions (as noted previously) it is not totally clear if this design basis will be directly applicable for an ASME Section III code case.

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Figure 20.3.3-27 Planned Test Points for Alloy 617 at 850ºC

Figure 20.3.3-28 Planned Test Points for Alloy 617 at 950ºC

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20.3.3.9.4 IHX Performance Verification DDNs

The development of directed materials and design code cases for the IHX is expected to require the verification of both performance and structural adequacy. Assuming selection of the recommended plate-type IHX, the required verification is expected to require experimental testing under various conditions expected in the NGNP. The objectives of the tests would be to validate models that are developed, to thoroughly understand the performance characteristics of these units under operational conditions and to establish models that will produce a reasonable estimate of unit life.

Tests could be performed in any facility suitable for this purpose; a preliminary test plan has been developed [Ref. 20.3.3-40]. The proposed IHX tests are based on the procedures and methodologies employed for military gas turbine recuperators, such as the advanced WR-21 engine developed by the U.S. and UK navies, and include stress and life model validation, durability testing, performance validation and materials testing. Four principal test objective categories are given below:

IHX stress and life prediction model validation tests - accurate predictions of thermal profile throughout the core and structure, assures accuracy of the FEA stress maps

IHX durability testing - the simulation of anticipated NGNP maneuvers, faults and failure modes

IHX performance testing - steady state validation of thermal effectiveness and pressure loss

Materials studies - evaluate long term exposure issues associated with He exposure, corrosion, velocity effects, erosion

20.3.3.10 Implications for the NGNP Pre-conceptual Design

The IHX is a key component for the NGNP, particularly if an indirect cycle configuration is used. Potential alloys that could be used to construct the IHX are not currently a part of the ASME Section III (nuclear code). A great deal of effort will be required to resolve this issue, because a reliable database potentially useful for a code case based on three well documented heats of material is not currently available for the alloys of interest. There is no existing ASME Section III design basis for either a conventional tube-and-shell or less-conventional plate type IHX. The approach to resolve this issue for the conventional IHX will not be clear until this issue is debated within the ASME. The resolution of utilizing a less conventional IHX design (which appears to have significant advantages for this application) appears to be the development of a formal design basis and submittal of a Section III code case associated with Subsection NH. A significant amount of effort will also be required to resolve this issue, because an openly available design basis is not currently available in a format suitable for a code case. Testing of prototype IHX units, if a plate type IHX is selected, is a prudent action that needs to be performed in support of the code case design basis for the specific IHX design selected. Testing should be performed on prototype units fabricated from both the metallic alloy selected and one or more ceramics that may have long term application for the IHX.

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20.3.3.11 Final Conclusions and Recommendations

The following IHX-related recommendations, which are derived from the ITRG review of the NGNP, have been confirmed by the present assessment, except as noted:

The reactor outlet temperature for the NGNP should not exceed 950ºC, based in part on IHX materials considerations.

As a result of this assessment, it is concluded that non-replaceable metallic components designed for the full plant lifetime (60 years) should be limited to ~850ºC versus 900ºC, as recommended by the ITRG. Metallic components operating at temperatures higher than ~850ºC, notably including high-temperature sections of the IHX, are likely to have reduced lifetimes and should be designed for replacement.

Time-dependent deformation for Class 1 pressure boundary components should be “insignificant”, as defined by the ASME Code.

The IHX should be designed to minimize stresses imposed on the metallic alloy due to the low margin of allowable creep stress associated with available metallic alloys operating in the 900-950ºC temperature range

Metallic materials should be limited to alloys listed in ASME Section II for Section III or Section VIII service.

Tube-and-shell IHXs are evaluated to be economically infeasible for commercial HTGR process heat applications, due to their size and cost. On this basis, the NGNP IHX should be a compact design. Among the compact heat exchangers, plate-type HXs, such as the Heatric Printed Circuit Heat Exchanger (PCHE), are evaluated to be more robust than plate-fin and/or primary surface concepts. It is, therefore, recommended that a plate-type HX development program should be pursued for the NGNP IHX in conjunction with an appropriate design and materials development program. Creep will need to be carefully considered for any IHX design (not previously a part of nuclear construction in the US). In this regard, the IHX should be enclosed within a Class 1 pressure boundary that operates at temperatures below which creep becomes significant.

While ceramic materials hold significant future promise, their selection for the initial NGNP IHX would pose an unacceptable risk to the NGNP schedule. Nevertheless, their potential for resolving the high-temperature issues associated with metals justifies an aggressive parallel development path. The primary issues associated with a ceramic IHX are very high cost, lack of standardization, lack of ASME Code acceptance, lack of a design basis, lack of availability within existing industry and the scale-up requirements for the NGNP application.

A variety of Heat Transport System (HTS) configurations are possible, based around direct or indirect cycle architectures. The procurement cost for the IHX would be much greater for an indirect cycle compared to a direct cycle system. Note that a plate-type IHX would consist of multiple modules connected in series and/or parallel. For large IHXs, such as would be used in indirect cycle architectures, this suggests consideration of a 2-Section IHX concept

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(Figure 20.3.3-29) in which the sections operating at the highest temperatures are separated from those operating at lower temperatures. The lower temperature sections would be designed as lifetime components, whereas the higher temperature sections would be designed to be replaceable, perhaps with a ceramic heat exchanger, when available. The impact of transients would have to be assessed for such designs.

PBMR

Metal

IHX

Metalor

SiCIHX

~950ºC

~850ºC

PBMR

Metal

IHX

Metalor

SiCIHX

Metal

IHX

Metal

IHX

Metalor

SiCIHX

Metalor

SiCIHX

Metalor

SiCIHX

~950ºC

~850ºC~850ºC

Figure 20.3.3-29 2-Section IHX Concept

The primary factors that have the most impact on the selection of metallic alloys for construction of the IHX include the following:

ASME Code acceptance (Section III preferably or alternatively Section VIII)

Adequate data base for the temperature region of the IHX

The data base must include mechanical properties of small grain size samples and diffusion bonds if a plate type heat exchanger (HX) is selected

The metallic alloy selected must be able to be easily welded and diffusion bonded (plate type HX)

The metallic alloy selected must be formable, machinable or etchable if a plate type HX is selected

The metallic alloy selected must have adequate creep rupture and mechanical properties in the region of 850-950C

The metallic alloy selected must be commercially available in large quantities

The metallic alloy selected must be available in multiple forms such as plate, tubing, forgings, etc

The metallic alloy selected must be fabricable into thin sheets if a plate type HX is used

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The metallic alloy selected must have reasonably stable properties during exposure to high temperatures for long time periods (thermal ageing)

The metallic alloy selected must be able to resist the corrosion effects of an impure He environment at high temperature

The metallic alloy selected must have reasonably stable and predictable mechanical and corrosion properties and microstructure over multiple heats within the ASTM/ASME chemical specification range (or for a modified specification) for the alloy

The metallic alloy selected should be a part of an ASME Code basis for the design of the HX

The Japanese used a conventional tube and shell IHX constructed of Hastelloy XR for the HTTR IHX. This is the most recent actual experience for a VHTR IHX. There are potentially a large number of very high temperature alloys that could be used for IHX construction; however, most are not ASME code materials or mature materials that have been used for multiple applications over many years. Alloys 617 or 230 are recommended for IHX construction depending on the stress and creep requirements of the design. Alloy 617 has been shown to have significant heat to heat variations in properties in the past and the specification for the alloy has been refined in the USC program to mitigate this issue. Ageing, particularly in the 700-750ºC range, can reduce some mechanical properties of either alloy. Long term exposure to impure He can cause corrosion to either alloy; however, it is believed that this can be controlled by an appropriate use of a He purification system. Grain size of these materials can affect high temperature properties and needs to be carefully considered.

Subsection NH is fundamentally sound, very conservative in several areas, has not been either accepted or rejected by the NRC, does not contain a good high temperature creep model for alloys such as 617, contains very limited materials not useful for the IHX and limits temperature to 760ºC. It is unclear how a new IHX code case would affect Subsection NH. It is recommended that the draft Alloy 617 code case submitted in 1992 not be revised. A new Section III code case should be submitted that is specific for the NGNP IHX.

ASME Section VIII contains materials useful for the design of the IHX, has a design basis for a tube and shell IHX and allows exposure temperatures up to 980ºC; however, this code is only applicable for non-nuclear applications. The approach that will be taken in the future by ASME to deal with the IHX issue is currently somewhat unclear. There is currently an initiative to address ASME issues regarding the NGNP; however, the IHX issue has not been addressed to date due to funding constraints.

The following additional recommendations are made:

It is recommended that an R&D program be performed to obtain adequate test data to support the code case for the IHX alloy selected

It is recommended that one or more small (100-200kW) prototype plate type HX units be procured for testing

It is recommended that detailed finite element analysis be performed on a plate type HX grid for use as a design and evaluation tool

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It is recommended that an alternate approach (separate from DOE/ASME Task 10) be implemented with appropriate ASME Code Committee representation and funded by the NGNP conceptual design contractors

It is recommended that initial discussions in support of the alternate approach be held with Bob Jetter ([email protected]), Chairman, ASME Section III, Subsection NH and Jim Ramirez ([email protected]), ASME Task Group Manager and other experts as appropriate

20.3.3.12 References for Section 20.3.3

20.3.3-1 ITRG, Design Features and Technology Uncertainties for the Next Generation Nuclear Plant, INEEL/EXT-04-01816, June 30, 2004.

20.3.3-2 Hayner et al, Next Generation Nuclear Plant Materials Research and Development Program Plan, INL/EXT-06-11701, Revision 3, August 2006.

20.3.3-3 Davis et al, Thermal-Hydraulic Analyses of Heat Transfer Fluid Requirements and Characteristics for Coupling a Hydrogen Production Plant to a High Temperature Nuclear Reactor, INL/EXT-05-00453, June 2005.

20.3.3-4 Harvego, Evaluation of Next Generation Nuclear Power Plant (NGNP) Intermediate Heat Exchanger (IHX) Operation Conditions, INL/EXT-06-11109, April 2006.

20.3.3-5 Lillo et al, Engineering Analysis of Intermediate Loop and Process Heat Exchanger Requirements to Include Configuration Analysis and Materials Needs, INL/EXT-05-00690, September 2005.

20.3.3-6 Tachibana, Development and Procurement of Hastelloy XR for the HTTR) Paper presented at Gen IV VHTR Materials and Components Project Management Board, Paris, September 2005.

20.3.3-7 McDonald, C.F., 1994. 20.3.3-8 Ward, M. E., “Primary Surface Recuperator Durability and Applications,”

Turbomachinery Technology Seminar, TTS006/395, Solar Turbines, Inc., San Diego, CA, 1995.

20.3.3-9 Maziasz, P. J., et. al., “Stainless Steel Foil with Improved Creep-Resistance for Use in Primary Surface Recuperators for Gas Turbine Engines,” in Gas Turbine Materials Technology, editors P. J, Maziasz, I. G. Wright, W. J. Brindley, J. Stringer and C. O’Brien, ASM International, Materials Park, OH, 1999, pp. 70-78.

20.3.3-10 Heatric, Heatric Web Site, www.heatric.com, 2006. 20.3.3-11 Li et al, Heat Exchangers for the Next Generation Nuclear Reactors, Paper 6105,

ICAPP 2006. 20.3.3-12 Dewson, The Development of High Efficiency Heat Exchangers for Helium Gas

Cooled Reactors), Paper 3213, ICAPP 03, 2003. 20.3.3-13 Natesan et al, “Materials Behavior in HTGR Environments,” NUREG/CR-6824

(ANL -02/37), Argonne National Laboratory, IL, 2003 20.3.3-14 Hayner et al, Next Generation Nuclear Plant Materials Research and Development

Program Plan, INL/EXT-05-00758, Revision 2, September 2005 20.3.3-15 Ren et al, Development of a Controlled Materials Specification for Alloy 617 for

Nuclear Applications, ORNL/TM-2005/504, May 30, 2005.

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20.3.3-16 AREVA, Review of Existing Data Base and R&D in Support of Codes and Standards Development) presented at Gen IV VHTR Materials and Components Project Management Board, ORNL, April 2005.

20.3.3-17 Duty and McGreevy, Impact of Deformation Mechanism Transition on Creep Behavior of Alloy 617, ORNL/GEN4/LTR-060-017, July 2006.

20.3.3-18 Ennis et al, Effect of Carburizing Service Environments on the Mechanical Properties of High Temperature Alloys, Nuclear Technology, 66, 363-368, January 31, 1984.

20.3.3-19 Cook, Creep Properties of Inconel 617 in Air and Helium at 800-1000C), Nuclear Technology 66, 283-288, August 1984.

20.3.3-20 Johnson, W. R. and G. Y. Lai, “Interaction of Metals with Primary Coolant Impurities: Comparison of Steam -Cycle and Advanced HTGRs,” in Specialist Meeting on High Temperature Metallic Materials for Application in Gas Cooled Reactors, Paper J1, 1981.

20.3.3-21 Burlet et. al., French VHTR Near Term High Temperature Alloy Development Program, GIF Materials and Components Project Management Board, Paris, September 2005.

20.3.3-22 Natesan, Preliminary Issues Associated with the NGNP IHX Design (external release pending), ANL/EXT-06-46, 2006.

20.3.3-23 Smith and Yates, Optimization of the Fatigue Properties of Inconel 617, Paper 91-GT-161, ASME International Gas Turbine and Aeroengine Congress and Exhibition, Orlando, Fl, 1991.

20.3.3-24 Stinton, D. P., Private Communication, 2006. 20.3.3-25 Omatete, O. O., et. al., Assessment of Recuperator Materials for Microturbines,

ORNL/TM-2000/304, 2000. 20.3.3-26 Bliem, C, et al, EG&G Idaho Falls, ID & J. I. Federer, ORNL, Oak Ridge, TN ,

Ceramic Heat Exchanger Concepts and Materials Technology, Noyes Publications, Park Ridge, NJ 1985.

20.3.3-27 Cleveland J.J. et al, Ceramic Heat Recuperators for Industrial Heat Recovery, Final Report for Contract EX-76-C-01-2 161 1980.

20.3.3-28 Brassell G.W. et al, Technology Assessment of Ceramic Joining Applicable to Heat Exchangers, EPRI AS-1586, TPS 77-748, 1980.

20.3.3-29 Tennery, V.J., Economic Application, Design Analysis, and Material Availability for Ceramic Heat Exchangers, ORNL/TM-7580, 1981.

20.3.3-30 Ward M.E et al, Ceramic Heat Exchanger Technology Development, final report from Solar Turbines, Inc. to DOE Contract No. DEACOI-80ETB712, DE-4898-F, 1982.

20.3.3-31 Smith, K.O., Ceramic Heat Exchanger Design Methodology, ANL/FE-84-6, 1984. 20.3.3-32 Blass J.J. et al, Design Methodology Needs for Fiber-Reinforced Heat Exchangers,

ORNL/TM 11012, 1990. 20.3.3-33 R. Lundberg R. et al, Ceramic Component Development for AGATA, ASME Paper

No. 99-GT-392, Indianapolis, IN, 1999. 20.3.3-34 McDonald, C.F., “Heat Recovery Exchanger Technology for Very Small Gas

Turbines,” International Journal of Turbo and Jet Engines, 13, 239-261, London, 1966.

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20.3.3-35 Shah V N.et al, Review and Assessment of Codes and Procedures for HTGR Components, NUREG/CR-6816, ANL-02/36, June 2003.

20.3.3-36 Jetter, Subsection NH Critical Issues and Concerns for Implementation, GIF, Materials and Component Project Management Board, ORNL, April 2005.

20.3.3-37 Kays, W.M. and London, A.L., Compact Heat Exchangers, Krieger Publishing Company, 1984.

20.3.3-38 Shah, R.K., Fundamentals of Heat Exchanger Design, Wiley, 2003. 20.3.3-39 Ren, Development of the GEN IV Materials Handbook, Weiju Ren, GIF PMB

Meeting, ORNL, April 2005. 20.3.3-40 Kesseli, et al, Conceptual Design for a High Temperature Gas Loop Test Facility,

INL/EXT-06-11648, August 2006

Additional References

Kihara, S, et al., “Morphological Changes of Carbides During Creep and Their Effects on the Creep Properties of Inconel 617 at 1000°C,” Metallurgical Transactions, 11A, p 1019, June 1980.

Generation IV 2002, Generation IV International Forum, A Technology Roadmap for Generation IV Nuclear Energy Systems, FIF-002-00, 2002

German-HTGR, Draft of “Part 2: Design, Construction, and Analysis,” German Code for Design of Very-High-Temperature Gas Cooled Reactor Components, KTA 3222.2, 1992.

Schneider K, et al, “Creep Behavior of Materials for High Temperature Reactor Application,” Nuclear Technology, 66, p 289, 1984.

Schubert, F et al., “Creep Rupture Behavior of Candidate Materials for Nuclear Process Heat Applications,” Nuclear Technology, 66, p 227, 1984.

ORNL-HTGR, H. McCoy, et al, “Mechanical Properties of Inconel 617 and 618,” Oak Ridge National Laboratory, ORNL/TM-9337, 1985.

Osthoff W, et al, “Creep and Relaxation Behavior of Inconel 617,” Nuclear Technology, 66, p 296, 1984.

Baldwin, D, O. Kimball, and R. Williams, “Design Data for Reference Alloys: Inconel 617 and Alloy 800H,” General Electric Company, DOE/HTGR-86-041, April 1986.

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20.3.4 HTS CONFIGURATION OPTIONS

In this section, the Heat Transport System (HTS) configurations that were evaluated as candidates for the NGNP preconceptual design are identified and described. As shown in Figure 20.3.4-1, the HTS options can be generally categorized in terms of the integration of the Power Conversion System (PCS) relative to the primary coolant circuit and the process coupling.

In the direct PCS configuration options, the power conversion turbomachinery is located directly within the primary helium loop. In the indirect PCS configuration options, the power conversion turbomachinery is isolated from the primary circuit by an intermediate heat exchanger (IHX). Indirect PCS configuration options are further categorized by whether the PCS is independently coupled to the secondary heat transport system (SHTS) circuit or integrated with the process itself. In the latter, all or part of the PCS coupling is located in the process streams beyond the process coupling heat exchanger (PCHX).

PBMR

Indirect PCSDirect PCS

Brayton Cycle

Series or Parallel IHX

Process Integrated

or No PCS

Steam Cycle

Secondary PCS

Steam Cycle

Gas Turbine

Combined Cycle

Series or Parallel IHX

Brayton Cycle

Series or Parallel IHX

Gas Turbine

Combined Cycle

Series or Parallel IHX

PBMR

Indirect PCSDirect PCS

Brayton Cycle

Series or Parallel IHX

Brayton Cycle

Series or Parallel IHXSeries or Parallel IHX

Process Integrated

or No PCS

Steam CycleSteam Cycle

Secondary PCS

Steam CycleSteam Cycle

Gas Turbine

Combined Cycle

Series or Parallel IHX

Gas Turbine

Combined Cycle

Series or Parallel IHXSeries or Parallel IHX

Brayton Cycle

Series or Parallel IHX

Brayton Cycle

Series or Parallel IHXSeries or Parallel IHX

Gas Turbine

Combined Cycle

Series or Parallel IHX

Gas Turbine

Combined Cycle

Series or Parallel IHXSeries or Parallel IHX

Figure 20.3.4-1 Process Heat/PCS Configuration Hierarchy

20.3.4.1 Direct Cycle PCS Options

In these direct cycle options, the PCS turbomachinery is located directly within the primary helium circuit. Helium circulation is provided by the gas turbine compressor.

20.3.4.1.1 Option 1: Primary Brayton Cycle/GTCC, Series IHX

In Option 1 (Figure 20.3.4-2, Table 20.3.4-1), thermal energy produced in the reactor is transferred to the SHTS and thence transported to the Hydrogen Production Unit (HPU) via a relatively small IHX that serves as a topping process to a direct Brayton cycle or, alternatively, to a Gas

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PBMR

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

RHX

Precooler

Intercooler

PT ~GBLPC HPC

RHXRHX

Precooler

Intercooler

PT ~GBLPC HPC

Intercooler

PT ~GBLPC HPC PT ~GBLPC HPC

OR*

PT ~GBCOMP

SG

HPT IPT LPT ~

RHX

Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

PT ~GBCOMP PT ~GBCOMP

SGSG

HPT IPT LPT ~

RHXRHX

Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

Metalor

SiCIHX

Note:

HyS shown as representative

H2 production process, could

also be S-I

PBMR

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

RHX

Precooler

Intercooler

PT ~GBLPC HPC

RHXRHX

Precooler

Intercooler

PT ~GBLPC HPC

Intercooler

PT ~GBLPC HPC PT ~GBLPC HPC

OR*OR*

PT ~GBCOMP

SG

HPT IPT LPT ~

RHX

Condenser

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Precooler-2

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Preheat Flow

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SGSG

HPT IPT LPT ~

RHXRHX

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Precooler-2

Ble

ed

Flo

w

Preheat Flow

Metalor

SiCIHX

Metalor

SiCIHX

Metalor

SiCIHX

Note:

HyS shown as representative

H2 production process, could

also be S-I

Figure 20.3.4-2 Option 1: Primary Brayton Cycle/GTCC, Series IHX

Table 20.3.4-1 Option 1: Primary Brayton Cycle/GTCC, Series IHX

Key Features

Small ( ~80MWt) topping IHX

Designed for easy replacement, but more difficult than parallel (Option 2)

Option to use liquid salt SHTS working fluid

Option to operate without IHX

Direct Brayton or GTCC bottoming cycle

Option to use 900ºC DPP PCS Readiness

Brayton cycle/GTCC based on DPP

No R&D at 900ºC or modest R&D to 950ºC

Option to operate PCS without IHX installed

Significant primary/ secondary flow mismatch

Primary side of IHX must be designed for full flow (potential issues with bypass/hot streaks)

SHTS circulator temperature an issue Support of Commercial Applications

Low NHS commonality with commercial PHP

May be inadequate as prototype for design certification of PHP commercial plants

GTCC variant supports deployment of AEP

Performance

Single PHTS flow path avoids operational issues with remixing of separate flows (Option 2)

PCS provides alternate heat sink (coolers) for off-normal events

Pressure transients associated with Brayton cycle transients must be considered

Cost

Capital

Along with Options 2 and 5, among lowest capital cost options

Small IHX implies modest replacement capital cost

Operating

Potential for good efficiency, high availability to maximize cost offsets via electric sales

PCS maintenance higher with direct cycle

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Turbine Combined Cycle (GTCC). The choice of a direct Brayton cycle or GTCC is a matter for further optimization, if required. The specific selection would be based on trade-offs between performance and cost, so as to optimize overall economics.

With Option 1, the size of the IHX would be limited by the performance characteristics of the Brayton cycle, which is very sensitive to turbine inlet temperature (TIT) (for details, see the PCS special study [Ref. 20.3.4-1]). At an IHX rating of 42 MW, the TIT would be close to that of the PBMR Demonstration Power Plant (DPP) (900ºC). At an IHX rating of 50 MW, the TIT would drop to ~890ºC.

With this configuration, the IHX may be designed for relatively easy removal and replacement. Operation without the IHX being installed is also a possibility. Note that, if the IHX is not installed, or the HPU is not in operation, the TIT would increase if the reactor is operated full capacity. For TITs above 900ºC, some turbine-related R&D may be required.

Since, in this configuration, all of the primary helium flow would be directed through the primary side of the IHX, there would be a significant primary/secondary flow mismatch. This factor leads to potential issues with bypass and/or hot streaks and tends to reduce commonality between the NGNP IHX and the corresponding commercial unit. Unless separate provisions for cooling are provided, the temperature of the helium returning to the IHX on the SHTS side would be relatively high. This would be a potential issue for the secondary circulator.

Option 1 would have relatively low commonality with commercial PBMR PHP applications, in which all of the thermal energy from the reactor is transferred via the IHX to the SHTS. While the anticipated modular nature of the IHX (assumed to be a compact heat exchanger) may allow technical extrapolations, it is questionable whether Option 1 would be sufficiently prototypical to support design certification of PBMR PHP commercial plants.

In terms of performance, the single primary system flow path avoids operational concerns with remixing of separate flows, an issue that will be seen with Option 2. The coolers which are located within the PCS can provide a heat sink for decay heat removal in the event of off-normal events. A significant issue with Brayton cycles is the pressure variations that would occur within the primary system during normal power maneuvering (inventory control) and upon collapse of the pressure ratio when the turbo-compressor unit is tripped. These events would impose significant pressure differentials relative to the SHTS, and represent an additional issue for metallic IHXs, for which pressure balanced operation will almost certainly be required.

Option 1, as well as Option 2, incorporate the least amount of PCS equipment and would, therefore, be among the lowest capital cost options. The relatively high efficiency of the direct Brayton cycle, along with the low parts count, which should be reflected in increased availability, are expected to maximize cost offsets via electric sales. Due to the potential for radionuclide contamination, PCS maintenance costs are expected to be higher.

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20.3.4.1.2 Option 2: Primary Brayton Cycle/GTCC, Parallel IHX

Option 2 (Figure 20.3.4-3, Table 20.3.4-2) is similar to Option 1, except that the IHX is placed in parallel with the PCS. As with Option 1, the IHX will be relatively small. In this case, the size of the IHX is limited by process temperature requirements and the effects of reduced volumetric flow in the Brayton cycle, rather than by reduced TIT. Due both to its small size and parallel architecture, removal and replacement of the IHX should be relatively easy with this configuration.

In this parallel arrangement, the direct Brayton cycle will, by necessity, operate at 950ºC. This increased TIT will require a modest R&D effort in support of the turbomachinery, relative to the DPP. Branching of the reactor outlet helium flow introduces additional design requirements on the gas ducting and liner systems. Also with the parallel flow arrangement, provisions will be needed to remix the parallel streams that are potentially at different temperatures. A trim heat exchanger is conceptually shown in Figure 20.3.4-3 for that purpose.

Option 2 adds a primary helium circulator. Flow control between the two parallel branches requires integrated control of the turbine-generator and the circulator.

As is the case with Option 1, lack of commonality with commercial PBMR PHP designs raises concerns with respect to support of licensing and design certification of commercial applications.

Other characteristics of Option 2 are similar to Option 1.

20.3.4.2 Indirect Cycle PCS Options

In these indirect cycle PCS options, the PCS is independent of the process and is either located within or coupled to a secondary circuit. Primary helium circulation is provided by a motor driven gas circulator. In the case of the Brayton and GTCC options, the Brayton section of the PCS turbomachinery operates within the SHTS. In the case of Rankine cycles, the steam generator is placed either within the primary helium or SHTS circuit.

20.3.4.2.1 Option 3: Secondary Brayton Cycle/GTCC, Series PCHX

In Option 3 (Figure 20.3.4-4, Table 20.3.4-3), all of the thermal energy produced in the reactor is transferred to the SHTS via the IHX. Within the SHTS, the PCHX and PCS are placed in a series arrangement, and are likely to become located to minimize the extent of high temperature piping. As with Option 1, the size of the IHX is limited by efficiency impacts on the PCS that are associated with reduced TIT. In this case, the impacts are more significant, since the maximum temperature available within the SHTS is 900ºC. This tends to make selection of the GTCC alternative more likely to improve efficiency.

In this and similar configurations, the IHX represents the most significant challenge to readiness in terms of meeting the NGNP objectives within the reference schedule. On the other hand, this and similar indirect cycle configurations provide maximum commonality with

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PBMR

Trim

HX

Mixer

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

PowerRHX

Precooler

Intercooler

PT ~GBLPC HPC

RHXRHX

Precooler

Intercooler

PT ~GBLPC HPC

Intercooler

PT ~GBLPC HPC PT ~GBLPC HPC

OR*

* To be selected in PCS Special

Study 20.4, if required

Metalor

SiCIHX

PT ~GBCOMP

SG

HPT IPT LPT ~

RHX

Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

PT ~GBCOMP PT ~GBCOMP

SGSG

HPT IPT LPT ~

RHXRHX

Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

PBMR

Trim

HX

Trim

HX

Mixer

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

PowerRHX

Precooler

Intercooler

PT ~GBLPC HPC

RHXRHX

Precooler

Intercooler

PT ~GBLPC HPC

Intercooler

PT ~GBLPC HPC PT ~GBLPC HPC

OR*

* To be selected in PCS Special

Study 20.4, if required

Metalor

SiCIHX

Metalor

SiCIHX

Metalor

SiCIHX

PT ~GBCOMP

SG

HPT IPT LPT ~

RHX

Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

PT ~GBCOMP PT ~GBCOMP

SGSG

HPT IPT LPT ~

RHXRHX

Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

Figure 20.3.4-3 Option 2: Primary Brayton Cycle/GTCC, Parallel IHX

Table 20.3.4-2 Option 2: Primary Brayton Cycle/GTCC, Parallel IHX

Key Features

Small ( ~50MWt) parallel IHX

Designed for easy replacement (easiest)

Option to operate without IHX

Direct Brayton cycle or GTCC

Requires 950ºC design basis Readiness

Brayton cycle/GTCC extrapolated from DPP

Modest R&D at 950ºC

Option to operate PCS without IHX installed

Facilitated by smaller, parallel PHTS piping

Requires provisions to control parallel flows, remix parallel streams that are potentially at different temperatures

Support of Commercial Applications

Low NHS commonality with commercial PHP

May be inadequate as prototype for design certification of PHP commercial plants

GTCC variant supports deployment of AEP

Performance

Parallel PHTS flow paths imply operational issues with remixing

PCS provides alternate heat sink (coolers) for off-normal events

Pressure transients associated with Brayton cycle transients must be considered

Cost

Capital

Along with Options 1 and 5, among lowest capital cost options

Small IHX implies modest replacement capital cost

Operating

Potential for good efficiency, good availability to maximize cost offsets via electric sales

PCS maintenance higher with direct cycle

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PBMR

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

RHX

Precooler

Intercooler

PT ~GBLPC HPC

RHXRHX

Precooler

Intercooler

PT ~GBLPC HPC

Intercooler

PT ~GBLPC HPC PT ~GBLPC HPC

OR*

* To be selected in PCS Special

Study 20.4, if required

Metal

IHX

Metalor

SiCIHX

PT ~GBCOMP

SG

HPT IPT LPT ~

RHX

Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

PT ~GBCOMP PT ~GBCOMP

SGSG

HPT IPT LPT ~

RHXRHX

Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

PBMR

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

RHX

Precooler

Intercooler

PT ~GBLPC HPC

RHXRHX

Precooler

Intercooler

PT ~GBLPC HPC

Intercooler

PT ~GBLPC HPC PT ~GBLPC HPC

OR*

* To be selected in PCS Special

Study 20.4, if required

Metal

IHX

Metalor

SiCIHX

Metal

IHX

Metal

IHX

Metalor

SiCIHX

Metalor

SiCIHX

Metalor

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PT ~GBCOMP

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HPT IPT LPT ~

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Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

Figure 20.3.4-4 Option 3: Secondary Brayton Cycle/GTCC, Series PCHX

Table 20.3.4-3 Option 3: Secondary Brayton Cycle/GTCC, Series PCHX

Key Features

Full-size IHX transfers all reactor heat to SHTS

Small ( ~50MWt) PCHX as topping cycle

Brayton cycle or GTCC bottoming cycle

850ºC PCS design basis

PCHX/PCS likely need to be co-located

Readiness

Brayton cycle/GTCC extrapolated from DPP

No R&D to 900ºC

Option to operate PCS without PCHX installed

Large IHX poses greatest challenge to readiness

Support of Commercial Applications

High NHS commonality with commercial PHP

If successful, resolves IHX issue for commercial plants

Adequate prototype for design certification of PHP commercial plants

GTCC variant supports deployment of AEP

Performance

PCS provides alternate heat sink (coolers) for off-normal events

Requires operational PHTS

Pressure transients associated with Brayton cycle transients must be considered

Significant availability risk associated with potential for IHX leaks

Cost

Capital

High capital cost relative to direct PCS options

Large IHX implies potential for high replacement capital costs

May be mitigated by selection of ceramic material and/or split section design

Operating

Lower efficiency, availability risk may reduce cost offsets via electric sales

Maintenance costs involve tradeoff of IHX/circulator vs. PCS

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commercial PBMR PHP plants, and will provide an ideal basis for resolving both technical and licensing barriers to their deployment. In particular, Option 3, and similar options, will provide an adequate basis for design certification of PBMR PHP commercial plants.

As suggested in the IHX/materials readiness assessment (Section 20.3.3), it is proposed that the IHX be structured within two major sections. The highest temperature section would be designed for ease of replacement, while the lower temperature section, defined as being within the capability of current metallic materials, would be a plant lifetime component. In concept, the high temperature section could be replaced with a ceramic IHX section when available.

Analogous to Option 1, the entirety of the SHTS flow is routed through the PCHX to the PCS. This will result in a mismatch of flow between the SHTS and process sides of the PCHX.

In terms of performance, the PCS coolers provide a heat sink for removal of decay heat when the normal combined HPU and PCS heat transport paths are unavailable. However in indirect cycle configurations, such as Option 3, operation of the primary heat transport system (PHTS) is required. With the Brayton cycle located in the SHTS, pressure transients associated with both normal and off normal operations must be taken into account in the design of the IHX.Since the IHX must be installed and functional to operate the plant, the IHX represents a significant risk to overall plant availability. In concept, this risk can be mitigated somewhat by the potential to remove the high temperature IHX section and operate the plant at lower reactor outlet temperature.

Both initial capital and replacement costs are expected to be higher with the indirect cycle architecture. Moving the PCS to the SHTS will also impact efficiency, and thus reduce cost offsets via electric sales. Maintenance costs would involve a trade-off between the IHX and circulator of the indirect cycles vs. the PCS of the direct cycles.

20.3.4.2.2 Option 4: Secondary Brayton Cycle/GTCC, Parallel PCHX

In Option 4 (Figure 20.3.4-5, Table 20.3.4-4), the PCHX is placed in parallel with the Brayton section of the PCS within the SHTS. Since the PCS operates at higher temperature, its efficiency would be improved relative to Option 3. As with Option 2, the size of the IHX is limited by process temperature requirements and volumetric flow influences on the parallel Brayton cycle. With the parallel arrangement, the flow rates through the SHTS and process sides of the PCHX can be matched at the module level, allowing the PCHX to be more nearly representative of commercial PBMR PHP applications.

Other attributes of Option 4 are similar to those of Option 3.

20.3.4.2.3 Option 5: Bottoming Steam Cycle, Series IHX

In Option 5 (Figure 20.3.4-6, Table 20.3.4-5), thermal energy from the reactor is routed to a small-to medium-size IHX, which serves as a topping process to a bottoming steam generator, both located within the primary helium circuit. Helium circulation in the PHTS is provided by a gas circulator. As in Options 1 and 2, the design of the IHX is intended to

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PBMROxygen Recovery

Hydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

PowerRHX

Precooler

Intercooler

PT ~GBLPC HPC

RHXRHX

Precooler

Intercooler

PT ~GBLPC HPC

Intercooler

PT ~GBLPC HPC PT ~GBLPC HPC

OR*

* To be selected in PCS Special

Study 20.4, if required

Metal

IHX

Metalor

SiCIHX

PT ~GBCOMP

SG

HPT IPT LPT ~

RHX

Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

PT ~GBCOMP PT ~GBCOMP

SGSG

HPT IPT LPT ~

RHXRHX

Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

PBMROxygen Recovery

Hydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

PowerRHX

Precooler

Intercooler

PT ~GBLPC HPC

RHXRHX

Precooler

Intercooler

PT ~GBLPC HPC

Intercooler

PT ~GBLPC HPC PT ~GBLPC HPC

OR*

* To be selected in PCS Special

Study 20.4, if required

Metal

IHX

Metalor

SiCIHX

Metal

IHX

Metal

IHX

Metalor

SiCIHX

Metalor

SiCIHX

Metalor

SiCIHX

PT ~GBCOMP

SG

HPT IPT LPT ~

RHX

Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

PT ~GBCOMP PT ~GBCOMP

SGSG

HPT IPT LPT ~

RHXRHX

Condenser

Precooler-1

Precooler-2

Ble

ed

Flo

w

Preheat Flow

Figure 20.3.4-5 Option 4: Secondary Brayton Cycle/GTCC, Parallel PCHX

Table 20.3.4-4 Option 4: Secondary Brayton Cycle/GTCC, Parallel PCHX

Key Features

Full-size IHX transfers all reactor heat to SHTS

Small ( ~50MWt) parallel PCHX

Brayton or GTCC cycle

Requires 900ºC design basis

PCHX/PCS likely to be co-located

Readiness

Brayton cycle/GTCC extrapolated from DPP

No R&D at 900ºC

Option to operate PCS without PCHX installed

Large IHX poses greatest challenge to readiness

Requires provisions to control parallel flows, remix parallel streams that are potentially at different temperatures

Support of Commercial Applications

High NHS commonality with commercial PHP

If successful, resolves IHX issue for commercial plants

Adequate prototype for design certification of PHP commercial plants

GTCC variant supports deployment of AEP

Performance

PCS provides alternate heat sink (coolers) for off-normal events

Requires operational PHTS

Parallel PHTS flow paths imply operational issues with remixing

Significant availability risk associated with potential for IHX leaks

Pressure transients associated with Brayton cycle transients must be considered

Cost

Capital

Higher capital cost relative to direct PCS options

Large IHX implies potential for high replacement capital costs

May be mitigated by selection of ceramic material and/or split section design

Operating

Lower efficiency, availability risk may reduce cost offsets via electric sales

Maintenance costs involve tradeoff of IHX/circulator vs. PCS

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PBMR

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Metalor

SiCIHX

SG

HPT IPT LPT ~

Ble

ed

Flo

wB

leed

Flo

w

CondenserSGSG

HPT IPT LPT ~

Ble

ed

Flo

wB

leed

Flo

w

Condenser

PBMR

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Metalor

SiCIHX

Metalor

SiCIHX

Metalor

SiCIHX

SG

HPT IPT LPT ~

Ble

ed

Flo

wB

leed

Flo

w

CondenserSGSG

HPT IPT LPT ~

Ble

ed

Flo

wB

leed

Flo

w

Condenser

Figure 20.3.4-6 Option 5: Bottoming Steam Cycle, Series IHX

facilitate easy replacement and the potential to operate the PCS without the IHX in place. Since all of the primary helium flow is routed through the IHX, there is, as with Option 1, a mismatch in flow relative to the secondary side of the IHX.

A key advantage of the bottoming Rankine cycle is the flexibility to apply a larger fraction of the reactor thermal output to the HPU (up to ~200 MW), without significantly impacting the efficiency of the PCS (this advantage is further elaborated in the discussion related to Option 6). In prior HTGR applications, steam generators have been operated for extensive periods with reactor outlet temperatures up to 950ºC.

While there is a potential to demonstrate the HPU at larger scale than is possible with other options already described, there is low commonality with the commercial PBMR PHP nuclear heat source. For this reason, Option 5 is unlikely to represent an adequate prototype for licensing and design certification of commercial PBMR PHP plants.

In terms of performance, steam provided to the PCS is at temperatures and pressures consistent with modern steam plants, with efficiencies projected to exceed 40%. As already noted, the Rankine cycle is less sensitive to thermal inputs than the corresponding Brayton cycles. The condenser of the steam cycle can serve as an alternate heat sink for decay heat removal, provided that the PHTS is functional. With the steam generator located in the primary loop, the potential for water ingress must be considered as part of the design and licensing process. There are no SHTS pressure transients associated with the Rankine cycle.

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Table 20.3.4-5 Option 5: Bottoming Steam Cycle, Series IHX

Key Features

Small to medium (Up to ~200MWt) topping IHX

Option to use liquid salt SHTS working fluid

Option to operate without IHX

Bottoming steam generator

700ºC-950ºC design basis, nominal depends on IHX rating

Readiness

Conventional steam cycle, with steam generator based on earlier HTGRs no R&D

Option to operate steam cycle without IHX installed

Significant mismatch between primary/ secondary flows

Primary side of IHX must be designed for full flow (potential issues with bypass/hot streaks)

Mismatch decreases as IHX power increases

SHTS circulator temperature an issue

Support of Commercial Applications

Larger engineering scale demonstrations of HyS/S-I feasible (up to ~100+ MWt)

Possibly even larger with reductions of SC efficiency. Low NHS commonality with commercial HyS/SI

Low NHS commonality with commercial PHP

May be inadequate as prototype for design certification of PHP commercial plants

Performance

PCS temperatures consistent with modern steam conditions

Steam cycle not as sensitive to thermal rating as GT cycles

Steam cycle provides alternate heat sink (coolers) for off-normal events

Requires operational PHTS

Potential for water ingress must be considered

Cost

Capital

Along with Options 1 and 2, among the lowest capital cost options

Small IHX implies modest replacement capital cost

Operating

Potential for reasonable efficiency, high availability to maximize cost offsets via electric sales

PCS maintenance conventional

Option 5, along with Options 1 and 2, is among the lowest capital costs options. It offers reasonably good efficiency and the prospect for high availability, in enhancing the potential for cost offsets via electric sales. PCS maintenance would be conventional. As further discussed in conjunction with Option 6, there is also a potential for long-term conversion of the NGNP to commercial hydrogen production, after its demonstration mission has been completed.

20.3.4.2.4 Option 6: Secondary Steam Cycle, Series PCHX

In Option 6 (Figure 20.3.4-7, Table 20.3.4-6), all of the reactor thermal energy is transferred to the SHTS via the IHX. Within the SHTS, high temperature helium is first directed to the PCHX and, thence, to a bottoming steam cycle. Helium is circulated within the PHTS by a gas circulator. As with Options 3 and 4, it is proposed that the IHX be structured within two sections, a high-temperature section designed for easy replacement and a lower temperature section designed as a lifetime component. There is a potential to operate the plant at lower reactor outlet temperatures without the high temperature section of the IHX being installed.

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PBMR

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Metal

IHX

Metalor

SiCIHX

SG

HPT IPT LPT ~

Ble

ed

Flo

wB

leed

Flo

w

CondenserSGSG

HPT IPT LPT ~

Ble

ed

Flo

wB

leed

Flo

w

CondenserPBMR

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Metal

IHX

Metalor

SiCIHX

Metal

IHX

Metal

IHX

Metalor

SiCIHX

Metalor

SiCIHX

Metalor

SiCIHX

SG

HPT IPT LPT ~

Ble

ed

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wB

leed

Flo

w

CondenserSGSG

HPT IPT LPT ~

Ble

ed

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wB

leed

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w

Condenser

Figure 20.3.4-7 Option 6: Secondary Steam Cycle, Series PCHX

As with Options 3 and 4, the IHX represents the most significant challenge to readiness, in terms of meeting the reference NGNP schedule. As with those other options, the indirect configuration also most closely represents the commercial PBMR PHP nuclear heat source. If successful, it will resolve the IHX issue for commercial plants and provide an adequate basis in support of licensing and design certification of commercial plants.

As previously noted with Option 5, the Rankine bottoming cycle provides a great deal of flexibility with respect to the amount of thermal energy that can be routed to the HPU. A preliminary assessment was made, based upon Option 6, to illustrate this point. Figure 20.3.4-8details the operating parameters for the plant when the HPU is not in operation. These parameters would be generally representative of HPU thermal power levels between 0 and 10 MW. Figure 20.3.4-9 illustrates the same Rankine cycle, operating at off-design conditions, with 200 MW directed to the HPU. Note that, while the helium temperature to the steam generator drops from 900ºC to 660ºC, the efficiency of the Rankine cycle decreases by only 6 percent. As further illustrated in Figure 20.3.4-11, the limit of the thermal power that can be withdrawn by the HPU, while still operating the Rankine cycle at high efficiency, is set by the pinch temperature within the steam generator. While 200 MW exceeds the levels contemplated for demonstration of the various hydrogen production processes, it does suggest that, after the NGNP completes its demonstration mission, there is a potential for converting the NGNP to commercial hydrogen production. While not specifically identified as an objective of the NGNP, such an option is consistent with the 60 year design life specified for the plant. This flexibility for longer term conversion of the NGNP to commercial production is also a potential with

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Table 20.3.4-6 Option 6: Secondary Steam Cycle, Series PCHX

Key Features

Full-size IHX transfers all reactor heat to SHTS

Small to Medium PCHX as topping cycle

Up to ~200MWt

Steam generator as bottoming cycle

700ºC-900ºC design basis, nominal depends on PCHX rating

PCHX/PCS likely to be co-located

Readiness

Conventional steam cycle, with steam generator based on earlier HTGRs no R&D

Option to operate PCS without PCHX installed

Large IHX poses greatest challenge to readiness

Support of Commercial Applications

Larger engineering scale demonstrations of HyS/S-I feasible (up to ~100MWt)

Possibly even larger with reductions of SC efficiency

High NHS commonality with commercial PHP

If successful, resolves IHX issue for commercial plants

Adequate prototype for design certification of PHP commercial plants

Performance

PCS temperatures consistent with modern steam conditions

Steam cycle not as sensitive to thermal rating as GT cycles

Steam cycle provides alternate heat sink for off-normal events

Requires operational PHTS and SHTS

Significant availability risk associated with potential for IHX leaks

Cost

Capital

Large IHX implies potential for high replacement capital costs

May be mitigated by selection of ceramic material and/or split section design

Operating

Lower efficiency, availability risk may reduce cost offsets via electric sales

Tradeoff of IHX/circulator vs. PCS maintenance costs

Option 5 and, with that option, an even greater thermal power level could be absorbed by the HPU.

The condenser section of the steam cycle can provide a continuous path for decay heat removal; however, with the steam generator being located in the SHTS, both the PHTS and SHTS must be operational.

As with Options 3 and 4, higher capital and operating costs and reduced efficiency are consequences of routing all of the thermal energy through the IHX. As noted above, however the efficiency impacts are modest over a wide range of HPU thermal power levels. These factors must be weighed against the ability of these indirect cycle options to better support commercial plant designs, in terms of risk mitigation and licensing/design certification.

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35

36

37

38

39

40

41

42

43

0 40 80 120 160 200 240

Hydrogen Plant Size (MWt)

Ran

kin

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ycle

Eff

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%]

Rankine Cycle Efficiency

Figure 20.3.4-10 Cycle L: Influence of Hydrogen Plant Size

H2 - 200 MW (Rankine 325 MW)SG Pinch Temperature of 25 C

H2 - 250 MW (Rankine 275 MW) SG Pinch Temperature of 7 C

H2 - 200 MW (Rankine 325 MW)SG Pinch Temperature of 25 C

H2 - 250 MW (Rankine 275 MW) SG Pinch Temperature of 7 C

Figure 20.3.4-11 Pinch Temperature Allows H2 Plant Sizes Up to ~200 MW

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20.3.4.3 Integrated PCS/Process Options – Option 7

This final category includes those options for which there is no identified PCS or in which all or part of the PCS is coupled directly to the process.

Option 7, which is the reference PBMR PHP commercial process for hydrogen production via HyS (Figure 20.3.4-12, Table 20.3.4-7) is an example of such coupling.

In this particular configuration, all of the reactor thermal energy is transferred to the SHTS, where it is first routed to the PCHX. Approximately 200 MW is transferred to the PCHX.Thereafter, the remaining thermal energy is extracted in the bottoming steam generator before the SHTS helium returns to the IHX. There is additional coupling between the process and the steam cycle to enhance overall thermal efficiency. A large fraction of the electricity generated in the PCS is utilized in the electrolysis section of the HyS process.

The technical difficulties associated with the indirect coupling of Option 7 are generally in common with Options 3, 4 and 6. Obviously, Option 7 ideally represents and supports the commercial PBMR PHP HyS application. However, it is incompatible with the stated mission of the NGNP to demonstrate multiple options. If, however, a single reference hydrogen production process could be selected, full-scale demonstration, followed by long-term commercial operation of the NGNP may provide the most cost-effective path to commercialization.

PBMR

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Fully Integrated PCS

SGSG

HPT LPT ~

Condenser

Preheater

Process Plant Battery Limits

Metal

IHX

Metalor

SiCIHX

PBMR

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

Preheating

H2

O2

H2O

Power

Fully Integrated PCS

SGSG

HPT LPT ~

Condenser

Preheater

Process Plant Battery Limits

Metal

IHX

Metalor

SiCIHX

Metal

IHX

Metal

IHX

Metalor

SiCIHX

Metalor

SiCIHX

Metalor

SiCIHX

Figure 20.3.4-12 Option 7: PCS Integrated with Process

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Table 20.3.4-7 Option 7: PCS Integrated with Process

Key Features

Full-size IHX transfers all reactor heat to SHTS

Full-size PCHX transfers all thermal energy to process

Steam cycle-based PCS integrated with process

Size/configuration is process dependent

Readiness

Large IHX poses greatest challenge to readiness

Requires process availability for operation

Minimum flexibility for demonstration of multiple applications

Requires reconfiguration of both process and PCS for individual applications

Support of Commercial Applications

Not consistent with HTE architecture

Up to full-scale demonstrations of PHP

High NHS commonality with commercial PHP

If successful, resolves IHX issue for commercial plants

Best prototype for design certification of PHP commercial plants

Performance

Prototypical of commercial applications

Provisions for alternate heat sink in SHTS or process are process dependent

Requires operational PHTS

Significant availability risk associated with potential for IHX leaks, process-related outages

Cost

Capital

Added cost for multiple demonstrations

Large IHX implies potential for high replacement capital costs

May be mitigated by selection of ceramic material and/or split section design

Operating

Low efficiency, availability likely to minimize cost offsets via electric sales

PCS maintenance costs moved to process

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20.3.4.4 Evaluation and Recommendation

The Heat Transport System (HTS) configuration options described in Sections 4.1 through 4.3 were evaluated against the criteria identified in Section 20.3.1.4. The result of the evaluation is summarized in Table 20.3.4-8. As earlier described in Section 20.3.1.4, each attribute was assigned an importance rating of low, medium or high. In the semi-quantitative process of Table 20.3.4-8, these importance factors were associated with weighting factors of 1, 2 and 3, respectively. Each option was evaluated against each attribute on the basis of 1 to 10.For each attribute, the HTS configuration option which best met that criterion was assigned an evaluation value of 10. The option which least well met the evaluation criteria was assigned a score of 1. Other HTS configurations were assigned relative values between 1 and 10. The evaluation values were multiplied by the weighting factors to obtain a score for each attribute. These were added to obtain the total score for the respective configurations.

In considering Table 20.3.4-8, it can be seen that Options 1, 2 and 5 scored relatively high in the categories of readiness, performance and cost. This is consistent with the relative simplicity of those configurations in comparison with their indirect cycle counterparts, which incorporate a full-size IHX. On the other hand, Options 1 and 2 score relatively low in terms of support for the design and licensing of commercial PBMR PHP applications and ability to meet operational performance goals. These latter attributes are highly weighted, since they are the essence of the NGNP mission to serve as a launching pad for commercial nuclear hydrogen production and related process heat applications. It is worthy to note that the relatively higher score of Option 5 principally relates to the flexibility of the bottoming Rankine cycle to accommodate a wide range of hydrogen production unit (HPU) thermal ratings.

The scores of Options 3, 4 and 6 are relatively high in terms of support for commercial applications and the ability to meet operational performance goals. They are also highly rated in terms of their serving as a basis for supplier infrastructure development. Lower ratings are found in the areas of readiness and cost, which relate to the incorporation of a full-size IHX that would serve as a prototype for follow-on commercial applications. The higher score of Option 6, relative to Options 3 and 4, again relates to the flexibility provided by the Rankine cycle to accommodate a range of HPU sizes. The latter also provides near-optimum opportunity for ultimate conversion of the NGNP to a commercial production status.

The ratings of Option 7, which is essentially a commercial hydrogen production prototype, are at the extremes of the range. Obviously, if successful, such an option would be an ideal basis for launching a commercial industry. On the other hand, risk is maximized and flexibility is minimized with such an option. Only if a single optimum hydrogen production process can be selected in the near term would it be worthwhile considering this option further.

On balance, it is recommended that Option 6 (Figure 20.3.4-13) be selected as the basis for the NGNP preconceptual design. Consistent with the evaluation, it is concluded that the incorporation of a full-size IHX best represents and supports commercial designs, and provides the optimum basis for licensing/design certification of the nuclear heat source for commercial process heat applications.

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Recognizing that direct Brayton cycle and related GTCC commercial applications will be adequately supported by the Demonstration Power Plant (DPP) in South Africa, Option 6 minimizes R&D and risk that is not directly associated with process heat and hydrogen production, the principal objectives of the NGNP. A specific example of the latter are pressure transients that would be imposed on the IHX by the Brayton cycle with Options 1 through 4.

Finally, the bottoming Rankine cycle provides the greatest flexibility for balancing the needs of the HPU demonstration and PCS. It also provides a clear path for conversion of the NGNP to commercial operation upon completion of its demonstration mission.

PBMR

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

PreheatingH

2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

PreheatingH

2

O2

H2O

Power

Metal

IHX

Metalor

SiCIHX

SG

HPT IPT LPT ~

Ble

ed

Flo

wB

leed

Flo

w

CondenserSGSG

HPT IPT LPT ~

Ble

ed

Flo

wB

leed

Flo

w

CondenserPBMR

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

PreheatingH

2

O2

H2O

Power

Oxygen RecoveryHydrogen Generation

Electrolyzer

Sulfuric Acid

DecompositionSulfuric Acid

PreheatingH

2

O2

H2O

Power

Metal

IHX

Metalor

SiCIHX

Metal

IHX

Metal

IHX

Metalor

SiCIHX

Metalor

SiCIHX

Metalor

SiCIHX

SG

HPT IPT LPT ~

Ble

ed

Flo

wB

leed

Flo

w

CondenserSGSG

HPT IPT LPT ~

Ble

ed

Flo

wB

leed

Flo

w

Condenser

Figure 20.3.4-13 Recommended HTS Configuration: Option 6

20.3.4.5 References for Section 20.3.4

20.3.4-1 NGNP Special Study: Power Conversion System, Revision C – Draft, M-Tech Industrial (Pty) Ltd., 20 December 2006. [to be updated]

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NG

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REFERENCES

References are identified in individual sections.

BIBLIOGRAPHY

Bibliography items are identified in individual sections.

DEFINITIONS

None.

REQUIREMENTS

Requirements are addressed in Section 20.3.1.

LIST OF ASSUMPTIONS

Section 20.3.1: Study Inputs

1. The requirements for Sulfur-Iodine and High-Temperature Electrolysis inferred from sources referenced in Section 20.3.1.1 are representative of actual requirements.

Section 20.3.3: IHX Materials Readiness Assessment

1. Plate-type heat exchangers can be manufactured from high temperature alloys and associated manufacturing processes will not degrade materials properties to an unacceptable level.

2. An acceptable metallic alloy can be procured and qualified for the range of 900-950ºC with properties that are acceptable for plate-type heat exchangers (e.g., grain size, as-bonded characteristics).

3. Relevant ASME Code Cases can be developed for the NGNP-specific design and materials in a timeframe consistent with the NGNP schedule.

4. A metallic IHX with adequate life can be developed for the temperature range of 900-950ºC.

TECHNOLOGY DEVELOPMENT

Technology development requirements identified through this HTS Special Study were limited to those related to the IHX. The Design Data Needs for the IHX are presented in Section 20.3.3.9.

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APPENDICES

The following appendices comprise the materials presented to BEA at the December 6-7, 2006 meetings in Stoughton, MA.

Appendix 20.3.1: Part 1 – Inputs and Criteria

Appendix 20.3.1: Part 2 – Power Conversion System Options

Appendix 20.3.1: Part 3 – HPU, IHX/Materials, SHTS Working Fluid

Appendix 20.3.1: Part 4 – Heat Transport System Options

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APPENDIX 20.3.1: SPECIAL STUDY 20.3.1 SLIDES

PART 1 – INPUTS AND CRITERIA

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/20.4

: P

art

1-

R1

-12/1

8/2

006

1

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ce

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er

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06

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6,

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06

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: P

art

1-

R1

-12/1

8/2

006

2

Ou

tlin

eO

utl

ine

•O

bje

cti

ve a

nd

Sco

pe

•S

tud

y In

pu

tsC

om

merc

ial applic

ations a

nd p

erf

orm

ance r

equirem

ents

Key N

GN

P H

TS

dem

onstr

ation o

bje

ctives

Key H

TS

functional re

quirem

ents

•S

cre

en

ing

Cri

teri

a

•H

2P

rod

ucti

on

Un

it S

ize (

20.7

)

•P

ow

er

Co

nvers

ion

Syste

m O

pti

on

s (

20.4

)

•IH

X/H

igh

-Tem

pera

ture

Mate

rials

•S

eco

nd

ary

Wo

rkin

g F

luid

•H

TS

Co

nfi

gu

rati

on

Op

tio

ns

•R

eco

mm

en

ded

HT

S C

on

fig

ura

tio

n

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art

1-

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-12/1

8/2

006

3

Ob

jec

tiv

eO

bje

cti

ve

Sele

ct

refe

ren

ce c

on

fig

ura

tio

ns f

or

the H

eat

Tra

nsp

ort

Syste

m (

HT

S)

an

d P

ow

er

Co

nvers

ion

Syste

m

(PC

S)

for

the N

GN

P P

reco

ncep

tual

Desig

n

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: P

art

1-

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-12/1

8/2

006

4

HT

S C

on

fig

ura

tio

n S

tud

y (

20

.3)

HT

S C

on

fig

ura

tio

n S

tud

y (

20

.3)

Sco

pe

Sco

pe

•Id

en

tify

an

d e

va

lua

te i

np

ut

req

uir

em

en

ts a

nd

/or

cri

teri

a t

ha

t w

ou

ld i

nfl

ue

nc

e

the H

TS

co

nfi

gu

rati

on

Fro

m P

BM

R P

HP

com

merc

ial develo

pm

ent activitie

s

Fro

m N

GN

P S

pecia

l S

tudie

s

–20.4

PC

S C

onfigura

tion O

ptions

–20.7

H2 p

lant siz

e

Fro

m I

NL/N

GN

P

•S

tep

1:

(th

e f

oll

ow

ing

in

pa

rall

el)

Identify

candid

ate

HT

S a

nd P

CS

configura

tions a

nd c

onduct in

itia

l scre

enin

g

Evalu

ate

SH

TS

work

ing flu

id o

ptions a

nd s

ele

ct re

fere

nce

Readin

ess e

valu

ation o

f IH

X/h

igh-t

em

pera

ture

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rials

: sele

ct

refe

rence

technolo

gy a

nd m

ate

rials

Develo

p c

rite

ria for

evalu

ation a

nd s

ele

ction

•S

tep

2:

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ate

an

d s

ele

ct

refe

ren

ce H

TS

co

ncep

t

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/20.4

: P

art

1-

R1

-12/1

8/2

006

5

Ou

tlin

eO

utl

ine

•O

bje

cti

ve a

nd

Sco

pe

•S

tud

y In

pu

tsC

om

merc

ial applic

ations a

nd p

erf

orm

ance r

equirem

ents

Key N

GN

P H

TS

dem

onstr

ation o

bje

ctives

Key H

TS

functional re

quirem

ents

•S

cre

en

ing

Cri

teri

a

•P

ow

er

Co

nvers

ion

Syste

m O

pti

on

s (

20.4

)

•H

2P

rod

ucti

on

Un

it S

ize (

20.7

)

•IH

X/H

igh

-Tem

pera

ture

Mate

rials

•S

eco

nd

ary

Wo

rkin

g F

luid

•H

TS

Co

nfi

gu

rati

on

Op

tio

ns

•R

eco

mm

en

ded

HT

S C

on

fig

ura

tio

n

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-12/1

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6

Pro

sp

ecti

ve C

om

merc

ial A

pp

licati

on

sP

rosp

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ve C

om

merc

ial A

pp

licati

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s

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lectr

ic P

lan

t A

pp

licati

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Multi-M

odule

Pow

er

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nt

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–B

rayto

n C

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merc

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llow

-on to D

em

onstr

ation P

ow

er

Pla

nt (D

PP

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Ad

va

nce

d E

lectr

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ow

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P)

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as-t

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om

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TC

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from

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s H

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t A

pp

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ia S

team

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ane R

efo

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R)

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rid

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lfu

r (H

yS

) P

roce

ss (R

ef.

1)

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via

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Iodin

e (

S-I

) P

rocess (R

ef.

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via

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h T

em

pe

ratu

re E

lectr

oly

sis

(H

TE

) (R

ef. 3

)

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art

1-

R1

-12/1

8/2

006

7

HH22

via

Hyb

rid

Su

lfu

r (H

yS

) C

ycle

via

Hyb

rid

Su

lfu

r (H

yS

) C

ycle

Co

mm

erc

ial P

lan

t C

on

fig

ura

tio

nC

om

merc

ial P

lan

t C

on

fig

ura

tio

n

(See

Ref.

1)

PB

MR

IHX

Ox

yg

en

Re

co

ve

ryH

yd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

Deco

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

Ox

yg

en

Re

co

ve

ryH

yd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

Deco

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

Fu

lly I

nte

gra

ted

PC

S

SG

SG

HP

TL

PT

~ Co

nd

en

se

r

Pre

heate

r

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cess P

lan

t B

att

ery

Lim

its

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/20.4

: P

art

1-

R1

-12/1

8/2

006

8

HH22

via

Su

lfu

rvia

Su

lfu

r --Io

din

e C

ycle

Iod

ine C

ycle

(So

urc

e:

Ref.

2)

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/20.4

: P

art

1-

R1

-12/1

8/2

006

9

HH22

via

Hig

h T

em

pera

ture

Ele

ctr

oly

sis

via

Hig

h T

em

pera

ture

Ele

ctr

oly

sis

(So

urc

e:

Ref.

3)

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: P

art

1-

R1

-12/1

8/2

006

10

Key C

om

merc

ial

Ap

plica

tio

n P

ara

mete

rsK

ey C

om

merc

ial

Ap

plica

tio

n P

ara

mete

rs

Hig

h T

em

p P

CH

X

Reacto

r/IH

X

917

925

900

IHX

Seco

nd

ary

Ou

tlet

Tem

pera

ture

, C

950

950

950

Co

re O

utl

et

Te

mp

era

ture

, C

10

100

100

Fra

cti

on

of

En

erg

y v

ia I

HX

, %

10

100

36

Fra

cti

on

of

En

erg

y v

ia P

CH

X,

%

772

900

872

Pro

ce

ss

Sid

e O

utl

et

Te

mp

, ºC

57

.08

.8P

rocess P

ressu

re, M

Pa

Ste

am

Gen

era

tor

an

dS

up

erh

eate

r

H2S

O4

Va

po

rize

r/

Deco

mp

oser

H2S

O4

Deco

mp

oser

Hig

h T

em

p P

CH

X

HT

ES

-IH

yS

Ap

pli

ca

tio

n

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11

Ou

tlin

eO

utl

ine

•O

bje

cti

ve a

nd

Sco

pe

•S

tud

y In

pu

tsC

om

merc

ial applic

ations a

nd p

erf

orm

ance r

equirem

ents

Key N

GN

P H

TS

dem

onstr

ation o

bje

ctives

Key H

TS

functional re

quirem

ents

•S

cre

en

ing

Cri

teri

a

•P

ow

er

Co

nvers

ion

Syste

m O

pti

on

s (

20.4

)

•H

2P

rod

ucti

on

Un

it S

ize (

20.7

)

•IH

X/H

igh

-Tem

pera

ture

Mate

rials

•S

eco

nd

ary

Wo

rkin

g F

luid

•H

TS

Co

nfi

gu

rati

on

Op

tio

ns

•R

eco

mm

en

ded

HT

S C

on

fig

ura

tio

n

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12

Ke

y H

TS

De

mo

ns

tra

tio

n O

bje

cti

ve

s:

Ke

y H

TS

De

mo

ns

tra

tio

n O

bje

cti

ve

s:

IHX

IHX

•T

he IH

X, w

hic

h t

ran

sfe

rs t

herm

al en

erg

y f

rom

th

e p

rim

ary

heat

tran

sp

ort

syste

m (

PH

TS

) to

th

e s

eco

nd

ary

heat

tran

sp

ort

syste

m

(SH

TS

), is a

co

mm

on

featu

re o

f co

mm

erc

ial ap

plicati

on

s r

eveale

d

to d

ate W

ith the e

xception o

f H

TE

, com

merc

ial configura

tions r

eveale

d to

date

depic

t all

of th

e r

eacto

r th

erm

al energ

y b

ein

g r

oute

d v

ia the

IHX

HT

E a

pplic

ation r

equires a

rela

tively

sm

all

fraction o

f th

erm

al

energ

y, w

ith the b

ala

nce b

ein

g p

rovid

ed a

s e

lectr

icity

•A

vailab

le m

eta

llic

mate

rials

are

marg

inal at

peak IH

X t

em

pera

ture

s

for

co

mm

erc

ially a

ccep

tab

le lif

eti

mes

Cera

mic

or

com

posite m

ate

rials

may o

ffer

accepta

ble

options, but

require s

ignific

ant develo

pm

ent

•T

he d

em

on

str

ati

on

of

an

accep

tab

le IH

X s

olu

tio

n is c

on

sid

ere

d a

nk

ey N

GN

P d

em

on

str

ati

on

ob

jecti

ve

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-12/1

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13

Ke

y H

TS

De

mo

ns

tra

tio

n O

bje

cti

ve

s:

Ke

y H

TS

De

mo

ns

tra

tio

n O

bje

cti

ve

s:

HH22

Pro

ce

ss

Pro

ce

ss

•In

teg

rate

d d

em

on

str

ati

on

of

ca

nd

ida

te H

2p

rod

uc

tio

n

pro

ce

ss

es

(in

clu

din

g t

he

pro

ce

ss

co

up

lin

g h

ea

t e

xc

ha

ng

er

-

PC

HX

) is

an

im

po

rta

nt

NG

NP

ob

jec

tiv

e

Therm

al re

quirem

ents

of

the H

TE

pro

cess a

re m

odest

The r

ecom

mended s

cale

for

dem

onstr

ating t

he H

yS

and S

-I

pro

cesses is a

ddre

ssed b

y a

separa

te s

tudy (

20.7

)

•A

dif

fere

nti

ati

ng

req

uir

em

en

t o

f th

e N

GN

P v

ers

us

co

mm

erc

ial ap

plicati

on

s is p

rovid

ing

th

e f

lexib

ilit

y t

o

dem

on

str

ate

mu

ltip

le p

rocesses

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14

Ke

y H

TS

De

mo

ns

tra

tio

n O

bje

cti

ve

s:

Ke

y H

TS

De

mo

ns

tra

tio

n O

bje

cti

ve

s:

Lic

en

sin

gL

icen

sin

g

•B

asis

fo

r licen

sin

g/c

ert

ific

ati

on

of

co

mm

erc

ial p

lan

ts

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15

Ke

y H

TS

De

mo

ns

tra

tio

n O

bje

cti

ve

s:

Ke

y H

TS

De

mo

ns

tra

tio

n O

bje

cti

ve

s:

Oth

er

HT

S C

om

po

nen

ts

Oth

er

HT

S C

om

po

nen

ts

•P

ipin

g a

nd

in

su

lati

on

De

sig

ns d

eve

lop

ed

an

d q

ua

lifie

d f

or

he

lium

to

95

0ºC

th

rough p

rior

HT

GR

pro

gra

ms +

PB

MR

DP

P

•C

ircu

lato

rs

Prio

r H

TG

R e

xp

erie

nce

su

pp

ort

s o

pe

ratio

n t

o ~

35

0ºC

PB

MR

DP

P is d

eve

lop

ing

po

ten

tia

lly a

pp

lica

ble

te

ch

no

log

ies

–M

agnetic b

earings for

Core

Conditio

nin

g S

yste

m c

ircula

tor

–D

ry G

as S

eals

for

Turb

om

achin

ery

•S

HT

S I

so

lati

on

Valv

es (

SIV

)

Need f

or

SIV

sto

be a

ssessed,

based o

n f

unctions a

nd

requirem

ents

of IH

X h

eat tr

ansfe

r surf

ace (

separa

tes

PH

TS

/SH

TS

) a

nd

SH

TS

pre

ssu

re b

ou

nd

ary

, p

lus lic

en

sin

g

co

nsid

era

tio

ns

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16

Ou

tlin

eO

utl

ine

•O

bje

cti

ve a

nd

Sco

pe

•S

tud

y In

pu

tsC

om

merc

ial applic

ations a

nd p

erf

orm

ance r

equirem

ents

Key N

GN

P H

TS

dem

onstr

ation o

bje

ctives

Key H

TS

functional re

quirem

ents

•S

cre

en

ing

Cri

teri

a

•P

ow

er

Co

nvers

ion

Syste

m O

pti

on

s (

20.4

)

•H

2P

rod

ucti

on

Un

it S

ize (

20.7

)

•IH

X/H

igh

-Tem

pera

ture

Mate

rials

•S

eco

nd

ary

Wo

rkin

g F

luid

•H

TS

Co

nfi

gu

rati

on

Op

tio

ns

•R

eco

mm

en

ded

HT

S C

on

fig

ura

tio

n

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17

So

urc

es o

f H

TS

Fu

ncti

on

al R

eq

uir

em

en

tsS

ou

rces o

f H

TS

Fu

ncti

on

al R

eq

uir

em

en

ts

NU

CL

EA

R H

EA

T S

OU

RC

E

HY

DR

OG

EN

PR

OD

UC

TIO

N

PL

AN

T

PR

IMA

RY

HE

AT

TR

AN

SP

OR

T

SY

ST

EM

SE

CO

ND

AR

Y

HE

AT

TR

AN

SP

OR

T

SY

ST

EM

NU

CL

EA

R

RE

AC

TO

R

Req

uir

em

en

tsR

eq

uir

em

en

ts

Pla

nt

Le

ve

l

Req

uir

em

en

ts

HE

AT

TR

AN

SP

OR

T S

YS

TE

M

(So

urc

e:

Ref.

5)

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18

Re

pre

se

nta

tiv

e H

TS

Re

pre

se

nta

tiv

e H

TS

Fu

ncti

on

s &

Req

uir

em

en

tsF

un

cti

on

s &

Req

uir

em

en

ts

•D

uri

ng

no

rmal o

pe

rati

on

, tr

an

sp

ort

an

d t

ran

sfe

r th

erm

al en

erg

y f

rom

th

e r

eacto

r to

th

e p

rocess a

nd

po

wer

co

nvers

ion

syste

m (

PC

S),

as a

pp

licab

le

Req

uir

em

en

ts:

Applic

ation-s

pecific

requirem

ents

: S

ee e

arlie

r ta

ble

Desig

n life: 60 y

ears

(lim

ited life c

om

ponents

to b

e r

epla

ceable

)

•D

uri

ng

oth

er

no

rmal (e

.g., s

tart

ing

up

/sh

utt

ing

do

wn

) an

d o

ff-n

orm

al (e

.g., lo

ss o

f p

rocess lo

ad

) o

pera

tio

nal sta

tes, tr

an

sp

ort

an

d t

ran

sfe

r th

erm

al

en

erg

y f

rom

th

e

reacto

r to

an

ult

imate

heat

sin

k

Req

uir

em

en

ts:

Duty

Cycle

: S

ee table

that

follo

ws

•M

ain

tain

co

ntr

ol

of

rad

ion

uclid

es

Req

uir

em

en

ts:

IHX

leakage r

equirem

ents

Tritium

-rela

ted r

equirem

ents

•P

rote

ct

Nu

cle

ar

Heat

So

urc

e f

rom

pro

cess-r

ela

ted

hazard

s

Req

uir

em

en

ts:

Dis

tance fro

m IH

X to p

rocess p

lant

Mitig

ating featu

res

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19

Re

pre

se

nta

tiv

e P

lan

t D

uty

Cy

cle

Re

pre

se

nta

tiv

e P

lan

t D

uty

Cy

cle

(So

urc

e:

Ref.

5)

C

om

pari

so

n o

f G

en

era

tin

g P

lan

t an

d H

yd

rog

en

Pro

du

cti

on

Pla

nt

Desig

n D

uty

Cycle

s

Nu

mb

er

of

Even

ts P

er

Po

wer

Un

it

Even

ts

Gen

era

tin

g H

TG

R

Hyd

rog

en

Pla

nt

HT

GR

Sta

rt-u

p f

rom

co

ld c

on

dit

ion

s

240

240

Sh

utd

ow

n t

o c

old

co

nd

itio

ns

240

240

No

rmal

load

fo

llo

win

g c

ycle

s(1

) 22,0

00

No

t A

pp

licab

le

Fre

qu

en

cy c

on

tro

l 800,0

00

No

t A

pp

licab

le

Lo

ad

reje

ct

to h

ou

se lo

ad

100

[25]

Rap

id lo

ad

ram

p

1500 u

p / 1

500 d

ow

n

[500]

do

wn

Ste

p lo

ad

ch

an

ges

3000

(1)

[500]

do

wn

(1) T

ota

l num

ber,

up o

r dow

n.

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1-

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-12/1

8/2

006

20

Ou

tlin

eO

utl

ine

•O

bje

cti

ve a

nd

Sco

pe

•S

tud

y In

pu

tsC

om

merc

ial applic

ations a

nd p

erf

orm

ance r

equirem

ents

Key N

GN

P H

TS

dem

onstr

ation o

bje

ctives

Key H

TS

functional re

quirem

ents

•S

cre

en

ing

Cri

teri

a

•P

ow

er

Co

nvers

ion

Syste

m O

pti

on

s (

20.4

)

•H

2P

rod

ucti

on

Un

it S

ize (

20.7

)

•IH

X/H

igh

-Tem

pera

ture

Mate

rials

•S

eco

nd

ary

Wo

rkin

g F

luid

•H

TS

Co

nfi

gu

rati

on

Op

tio

ns

•R

eco

mm

en

ded

HT

S C

on

fig

ura

tio

n

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-12/1

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21

Scre

en

ing

Cri

teri

aS

cre

en

ing

Cri

teri

a

Att

rib

ute

Imp

ort

an

ce

•R

ead

iness

Ab

ilit

y t

o m

ee

t N

GN

P t

ime

lin

e (

sta

rtu

p:

20

16

-201

8)

Hig

h

NG

NP

R&

D R

equirem

ents

/Cost/R

isk

Med

Vendor/

Supplie

rIn

frastr

uctu

re D

evelo

pm

ent

Med

•S

up

po

rt o

f C

om

merc

ial

Ap

pli

ca

tio

ns

Ad

eq

uate

ly d

em

on

str

ate

s c

om

merc

ial

pro

cess h

eat

Hig

ha

pp

lic

ati

on

s

NH

S c

om

mo

na

lity

wit

h c

om

merc

ial

pro

du

cts

Hig

h

Can

serv

e a

s p

rocess h

eat

pro

toty

pe f

or

desig

n c

ert

ific

ati

on

Hig

h

Fle

xib

ility

for

dem

onstr

ating a

dvanced a

pplic

ations

Med

Fle

xib

ility

for

ultim

ate

NG

NP

convers

ion t

o f

ull-

scale

H2 p

roduction

Med

•P

erf

orm

an

ce

Ab

ilit

y t

o m

ee

t o

pe

rati

on

al

pe

rfo

rma

nc

e g

oa

lsH

igh

Overa

ll P

lant

Effic

iency

Low

Opera

bili

tyM

ed

Availa

bili

tyLow

•C

ost

NG

NP

Ca

pit

al

Co

st

Hig

h

NG

NP

Opera

ting C

ost

Low

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22

Pa

rt 1

Re

fere

nc

es

Pa

rt 1

Re

fere

nc

es

1.

La

ho

da

, E

.J.,

et.

al.

, “E

sti

ma

ted

Co

sts

fo

r th

e I

mp

rov

ed

HyS

Flo

ws

heet”

, H

TR

20

06

, O

cto

be

r 2006.

2.

H2-M

HR

Co

ncep

tual

Desig

n R

ep

ort

: S

I-B

ased

Pla

nt

(GA

-A25401),

Gen

era

l A

tom

ics,

Ap

ril

2006.

3.

H2-M

HR

Co

ncep

tual

Desig

n R

ep

ort

: H

TE

-Based

Pla

nt

(GA

-A25402),

Gen

era

l A

tom

ics,

Ap

ril

2006.

4.

Pro

cess H

eat

Pla

nt-

5:

Ste

am

Meth

an

e R

efo

rmin

g P

rocess F

low

Dia

gra

m (

Pre

lim

), S

haw

Decem

ber

2005.

5.

“H

igh

Te

mp

era

ture

Ga

s-C

oo

led

Re

acto

rs f

or

the

Pro

du

cti

on

of

Hyd

rog

en

: E

sta

bli

sh

me

nt

of

the

Qu

an

tifi

ed

Te

ch

nic

al

Re

qu

irem

en

ts f

or

Hyd

rog

en

Pro

du

cti

on

th

at

wil

l S

up

po

rt t

he

Wa

ter-

Sp

litt

ing

Pro

cesses a

t V

ery

Hig

h T

em

pera

ture

s”,

EP

RI, P

alo

Alt

o,

CA

: 2

004.

1009687.

6.

Te

ch

no

-eco

no

mic

Co

mp

ari

so

n o

f P

CU

'sfo

r th

e N

GN

P,

PB

MR

, S

ep

tem

be

r 2

005.

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1-

R1

-12/1

8/2

006

23

Ou

tlin

eO

utl

ine

•O

bje

cti

ve a

nd

Sco

pe

•S

tud

y In

pu

tsC

om

merc

ial applic

ations a

nd p

erf

orm

ance r

equirem

ents

Key N

GN

P H

TS

dem

onstr

ation o

bje

ctives

Key H

TS

functional re

quirem

ents

•S

cre

en

ing

Cri

teri

a

•P

ow

er

Co

nvers

ion

Syste

m O

pti

on

s (

20.4

)

•H

2P

rod

ucti

on

Un

it S

ize (

20.7

)

•IH

X/H

igh

-Tem

pera

ture

Mate

rials

•S

eco

nd

ary

Wo

rkin

g F

luid

•H

TS

Co

nfi

gu

rati

on

Op

tio

ns

•R

eco

mm

en

ded

HT

S C

on

fig

ura

tio

n

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APPENDIX 20.3.1: SPECIAL STUDY 20.3.1 SLIDES

PART 2 – POWER CONVERSION SYSTEM OPTIONS

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1

SP

EC

IAL

ST

UD

IES

:S

PE

CIA

L S

TU

DIE

S:

20

.32

0.3

--H

EA

T T

RA

NS

PO

RT

SY

ST

EM

H

EA

T T

RA

NS

PO

RT

SY

ST

EM

20

.42

0.4

--P

OW

ER

CO

NV

ER

SIO

N S

YS

TE

M

PO

WE

R C

ON

VE

RS

ION

SY

ST

EM

Pa

rt 2

P

art

2 ––

Po

wer

Co

nvers

ion

Syste

m O

pti

on

sP

ow

er

Co

nvers

ion

Syste

m O

pti

on

s

De

ce

mb

er

6,

20

06

De

ce

mb

er

6,

20

06

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2

Ba

ck

gro

un

dB

ac

kg

rou

nd

•T

he c

ho

ice o

f P

ow

er

Co

nvers

ion

Syste

m (

PC

S)

is a

vit

al

ste

p i

n t

he

Pre

co

nc

ep

tua

l D

es

ign

of

the

NG

NP

•T

he P

CS

dir

ectl

y i

nfl

uen

ces

Pla

nt

ne

t e

ffic

ien

cy

Pra

cticalit

y o

f th

e c

om

ponent

desig

ns

Pla

nt fle

xib

ility

Pla

nt

co

st

Po

ten

tia

l te

ch

no

log

y g

row

th

•Id

en

tify

ing

th

e o

pti

mu

m P

CS

is a

co

mp

lex p

rob

lem

wh

ich

is in

flu

en

ce

d b

y a

la

rge

nu

mb

er

of

inte

rde

pe

nd

en

t

vari

ab

les

pra

ctical

effic

ient

$$

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3

Ob

jec

tiv

eO

bje

cti

ve

•A

na

lyze

an

d c

om

pa

re t

he

pe

rfo

rma

nc

e o

f

thre

e P

CS

fa

mil

ies

be

ing

co

ns

ide

red

in

co

nju

nc

tio

n w

ith

He

at

Tra

ns

po

rt S

ys

tem

(HT

S)

op

tio

ns

Ga

s T

urb

ine

(B

rayto

n)

Cycle

s

Ga

s T

urb

ine

Co

mb

ine

d C

ycle

s (

CC

GT

)

Ra

nkin

eC

ycle

s

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4

PC

S O

pti

on

s In

ve

sti

ga

ted

PC

S O

pti

on

s In

ve

sti

ga

ted

PB

MR

Ind

irect

PC

SD

ire

ct

PC

S

Bra

yto

n C

yc

leP

rocess I

nte

gra

ted

or

No

PC

S

Ste

am

Cyc

le

Seco

nd

ary

PC

S

Ste

am

Cyc

leG

as T

urb

ine

Co

mb

ine

d C

yc

leB

rayto

n C

yc

le

Gas T

urb

ine

Co

mb

ine

d C

yc

le

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5

Part

2 O

utl

ine

Part

2 O

utl

ine

•In

tro

du

cti

on

•A

na

lys

is M

eth

od

olo

gy

•E

va

lua

tio

n

Bra

yto

n C

ycle

s

GT

CC

Ra

nkin

e C

ycle

s

•C

ycle

Tra

de-o

ffs

•S

um

ma

ry

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6

An

aly

sis

Me

tho

do

log

y

An

aly

sis

Me

tho

do

log

y

•In

teg

rate

d a

na

lys

is a

pp

roa

ch

•S

yste

mati

cally c

om

pare

s

vari

ou

s c

ycle

co

nfi

gu

rati

on

s

ba

se

d o

n t

he

sa

me

in

pu

t

pa

ram

ete

rs

•E

valu

ate

th

e e

ffic

ien

cy a

s a

fun

cti

on

of

vari

ou

s d

esig

n

pa

ram

ete

rs

Cy

cle

Cycle

an

aly

sis

Co

mp

on

en

t M

od

el

Resu

lts

Sam

e input

variable

s pre

ssure

s

tem

pera

ture

s

mass f

low

s

cycle

effic

iency

perf

orm

conceptu

al

com

ponent desig

n

(desig

ned t

o level of

deta

il re

quired b

y

siz

ing f

orm

ula

)

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7

Infl

ue

nc

e o

f H

Infl

ue

nc

e o

f H

22P

rod

ucti

on

Un

itP

rod

ucti

on

Un

it

•T

he s

ize o

f th

e H

2P

rod

ucti

on

Un

it (

HP

U)

will b

e r

ela

tively

sm

all ~5 -

50M

Wt per

20.7

•It

is, th

ere

fore

, assu

med

th

at

the s

ize o

f th

e H

PU

will n

ot

sig

nif

ican

tly i

nfl

uen

ce t

he c

ho

ice o

f th

e b

est

cycle

co

nfi

gu

rati

on

wit

hin

a g

iven

fam

ily

(Bra

yto

n, G

TC

C,

Ra

nk

ine

)

There

fore

, w

hen c

om

paring c

ycle

variations w

ithin

these

thre

e in

div

idu

al g

rou

ps,

the

HP

U s

ize

is n

ot

dire

ctly

co

nsid

ere

d

•F

or

the o

pti

mu

m c

ycle

wit

hin

each

fam

ily, th

e in

flu

en

ce o

f

HP

U s

ize is s

ub

seq

uen

tly e

valu

ate

d

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8

Cy

cle

An

aly

sis

Cy

cle

An

aly

sis

•In

pu

t vari

ab

les t

og

eth

er

wit

h b

asic

th

erm

od

yn

am

ic r

ela

tio

ns, are

used

to

calc

ula

te t

he t

em

pera

ture

s a

nd

pre

ssu

res a

t each

c

om

po

ne

nt’

s i

nle

t a

nd

ou

tle

t

•B

rayto

n c

ycle

Fix

ed h

eat exchanger

effic

iencie

s

Fix

ed p

ressure

dro

p p

erc

enta

ges for

pip

ing a

nd h

eat exchangers

Fix

ed r

eacto

r desig

n

Fix

ed c

om

pre

ssor

and turb

ine e

ffic

iencie

s

•R

an

kin

e c

ycle

Maxim

um

ste

am

pre

ssure

is fix

ed

Upper

limit is s

et fo

r m

axim

um

ste

am

tem

pe

ratu

re

Turb

ine a

nd p

um

p e

ffic

iencie

s a

re fix

ed

Fix

ed p

ressure

dro

p p

erc

enta

ges thro

ugh S

G a

nd r

e-h

eate

r

Optim

ize R

IT for

maxim

um

GT

CC

effic

iency

Lim

it low

pre

ssure

turb

ine o

utlet qualit

y to m

ore

than 8

8%

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9

Cy

cle

Op

tim

iza

tio

n

Cy

cle

Op

tim

iza

tio

n

•G

as

Tu

rbo

Un

its

Com

bin

ation o

f speed, bla

de s

afe

ty facto

r, e

tc. w

as

optim

ized to e

nsure

the m

inim

um

capital cost (s

malle

st

machin

e)

at every

opera

ting p

oin

t

•G

TC

C

Rankin

eC

ycle

was c

usto

m-d

esig

ned to e

xactly fit the

Bra

yto

n c

ycle

at

every

consid

ere

d o

pera

ting p

oin

t

Bra

yto

ncycle

and R

ankin

ecycle

were

optim

ized t

o e

nsure

th

e m

axim

um

com

bin

ed e

ffic

iency a

t every

opera

ting p

oin

t

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10

Inp

ut

Pa

ram

ete

rs

Inp

ut

Pa

ram

ete

rs

•R

an

kin

e C

ycle

in

pu

ts

Maxim

um

ste

am

pre

ssu

re =

180 b

ar

Co

nd

en

ser

tem

pera

ture

= 3

5°C

Tu

rbin

e e

xh

au

st

qu

ali

ty =

~0

.88

turb

ine

= 8

9%

; p

um

ps

= 7

2%

SG

an

d r

e-h

ea

ter

pre

ss

ure

dro

p =

3%

of

inle

t

pre

ssu

re

Pip

ing

pre

ssu

re d

rop

ig

no

red

HL

Ran

kin

e=

0.9

915*P

ow

er R

an

kin

e

Pin

ch

Tem

pera

ture

= 3

0°C

•R

an

kin

e C

ycle

co

nstr

ain

ts

Max s

team

tem

pera

ture

540°C

•G

TC

C i

np

uts

(G)(

J)

HL

CC

= 0

.8*H

LB

rayto

n+

0.9

915*P

ow

er R

an

kin

e

(H)(

I) H

LC

C=

0.6

*HL

Bra

yto

n+

0.9

915*P

ow

er R

an

kin

e

•G

en

eri

c i

np

uts

PB

R p

ow

er

= 5

00 M

Wth

DP

P R

eacto

r d

esig

n

Pri

ma

ry a

nd

se

co

nd

ary

flu

id =

He

liu

m

•B

rayto

n C

yc

le i

np

uts

Tu

rbin

e i

nle

t te

mp

era

ture

= 9

00°C

(assu

med

fo

r 20.4

)

Min

he

liu

m c

oo

lan

t te

mp

= 2

2.5°C

(as

su

me

d f

or

20.4

)

co

mp

res

so

r=

89

%;

turb

ine

= 9

1%

; b

low

er=

80

%

Co

mp

resso

r o

utl

et

axia

l velo

cit

y =

135 m

/s

recu

pera

tor=

97

%

IHX

pre

ssu

re d

rop

= 0

.5%

of

inle

t p

res

su

re

Pip

ing

pre

ss

ure

dro

p =

0.2

% o

f in

let

pre

ss

ure

Bra

yto

n h

ou

se

loa

d (

HL

) =

6.5

MW

e

Pri

mary

cir

cu

it m

axim

um

pre

ssu

re =

9 M

Pa

IHX

ap

pro

ach

tem

pera

ture

= 5

0°C

(in

dir

ect

cycle

s)

Seco

nd

ary

cir

cu

it p

ressu

re =

8.8

MP

a

•R

eacto

r an

d B

rayto

n C

ycle

co

nstr

ain

ts

Maxim

um

RIT

= 5

00°C

(C

ore

Barr

el

< 4

27°C

)

Maxim

um

mass f

low

= 2

00 k

g/s

(V

< 1

00m

/s)

Ma

xim

um

Tu

rbo

Un

it p

res

su

re r

ati

o =

3.5

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11

Part

2 O

utl

ine

Part

2 O

utl

ine

•In

tro

du

cti

on

•A

na

lys

is M

eth

od

olo

gy

•E

va

lua

tio

n

Bra

yto

n C

ycle

s

GT

CC

Ra

nkin

e C

ycle

s

•C

ycle

Tra

de-o

ffs

•S

um

ma

ry

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12

Bra

yto

n C

yc

le C

on

fig

ura

tio

ns

Bra

yto

n C

yc

le C

on

fig

ura

tio

ns

•(A

) S

ing

le-s

haft

•(B

) S

ing

le-s

haft

wit

h in

ter-

co

olin

g

•(C

) T

wo

-sh

aft

wit

h in

ter-

co

olin

g

•(D

) T

hre

e-s

haft

wit

h i

nte

r-co

olin

g

•(E

)* T

hre

e-s

haft

wit

h t

wo

-ste

p in

ter-

co

olin

g

*In

dir

ec

t C

yc

le F

to

fo

llo

w l

ate

r

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13

Bra

yto

n C

yc

le O

pti

on

sB

ray

ton

Cy

cle

Op

tio

ns

A, B

, C

A, B

, C

(A)

Sin

gle

-sh

aft

(B)

Sin

gle

-sh

aft

wit

h

inte

r-co

olin

g

(C)

Tw

o-s

ha

ft w

ith

inte

r-co

oli

ng

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14

Bra

yto

n C

yc

le O

pti

on

sB

ray

ton

Cy

cle

Op

tio

ns

D,

ED

, E

(D)

Th

ree

-sh

aft

wit

h

inte

r-co

olin

g

(E)

Th

ree-s

haft

wit

h t

wo

-

ste

p in

ter-

co

olin

g

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15

0.3

5

0.3

6

0.3

7

0.3

8

0.3

9

0.4

0

0.4

1

0.4

2

0.4

3

0.4

4

0.4

5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

To

tal

Bra

yto

n P

ress

ure

Ra

tio

Efficiency [%]

Cycle

AC

ycle

BC

ycle

CC

ycle

DC

ycle

E

Bra

yto

n C

yc

les

Bra

yto

n C

yc

les

Net

Cycle

Eff

icie

ncy

Net

Cycle

Eff

icie

ncy

•B

est

eff

icie

ncy –

Cycle

B:

Sin

gle

sh

aft

Bra

yto

n c

ycle

wit

h i

nte

rco

ole

r

Net

eff

icie

ncy v

s. P

ressu

re r

ati

o

(A)1

-Sh

aft

(B)1

-Sh

aft

IC

(C)2

-Sh

aft

IC

(D)3

-Sh

aft

IC

(E)3-S

haft

IC

x2

Turb

ine

inle

t te

mp

era

ture

of

90

0°C

Pow

er

turb

ine

sp

ee

d o

f 1

00 r

ev/s

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16

250

300

350

400

450

500

550

600

650

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

To

tal

Bra

yto

n P

ressu

re R

ati

o

RIT [C]

Cycle

AC

ycle

BC

ycle

CC

ycle

DC

ycle

E

Bra

yto

n C

yc

les

Bra

yto

n C

yc

les

RIT

RIT

•M

ax

imu

m R

IT o

f 5

00°C

; to

en

ab

le C

ore

Barr

el to

op

era

te b

elo

w 4

27°C

All

cycle

s to o

pera

te a

bove 3

.1 p

ressure

ratio to e

nable

RIT

< 5

00°C

RIT

vs. P

ressu

re r

ati

o

(A)1

-Sh

aft

(B)1

-Sh

aft

IC

(C)2

-Sh

aft

IC

(D)3

-Sh

aft

IC

(E)3-S

haft

IC

x2

Turb

ine

inle

t te

mp

era

ture

of

90

0°C

Pow

er

turb

ine

sp

ee

d o

f 1

00 r

ev/s

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17

150

170

190

210

230

250

270

290

310

330

350

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

To

tal

Bra

yto

n P

ress

ure

Ra

tio

Massflow Rate [kg/s]

Cycle

AC

ycle

BC

ycle

CC

ycle

DC

ycle

E

Bra

yto

n C

yc

les

Bra

yto

n C

yc

les

Mass F

low

Rate

Mass F

low

Rate

•M

ax

imu

m m

as

s f

low

of

~2

00

kg

/s;

to l

imit

re

ac

tor

co

re v

elo

cit

y

Bra

yto

n c

ycle

s u

nable

to o

pera

te a

t th

eir m

axim

um

cycle

effic

iency w

ithin

reacto

r desig

n e

nvelo

pe a

t 500 M

W

Mass f

low

rate

vs. P

ressu

re r

ati

o

(A)1

-Sh

aft

(B)1

-Sh

aft

IC

(C)2

-Sh

aft

IC

(D)3

-Sh

aft

IC

(E)3-S

haft

IC

x2

Turb

ine

inle

t te

mp

era

ture

of

90

0°C

Pow

er

turb

ine

sp

ee

d o

f 1

00 r

ev/s

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18

0.7

5

0.8

5

0.9

5

1.0

5

1.1

5

1.2

5

1.3

5

1.4

5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

To

tal

Bra

yto

n P

ress

ure

Ra

tio

Relative Turbo Unit Sizes

Cycle

AC

ycle

BC

ycle

CC

ycle

DC

ycle

E

Bra

yto

n C

yc

les

Bra

yto

n C

yc

les

Rela

tive T

urb

o U

nit

Siz

eR

ela

tive T

urb

o U

nit

Siz

e

•S

ing

le-s

haft

desig

ns h

ave h

igh

est

gra

die

nts

(fi

xed

ro

tati

on

al sp

eed

)

•T

hre

e-s

haft

desig

ns h

ave l

ow

est

gra

die

nt

(on

ly t

hir

d s

ha

ft h

as

a f

ixe

dro

tati

on

al

sp

ee

d)

–fr

ee

sh

aft

s r

ota

tio

na

l s

pe

ed

op

tim

ize

d

Rela

tive t

urb

o u

nit

siz

e v

s. P

ressu

re r

ati

o

(A)1

-Sh

aft

(B)1

-Sh

aft

IC

(C)2

-Sh

aft

IC

(D)3

-Sh

aft

IC

(E)3-S

haft

IC

x2

Siz

e is a

function o

f tip r

adiu

s

(rt) a

nd

nu

mb

er

of

sta

ge

s (

z)

F()

= k

1r t

2(k

2z +

k3)

(*S

ee

ap

pe

nd

ix f

or

eff

ect

of

rota

tio

na

l s

pe

ed

an

d R

OT

)

*

Turb

ine

inle

t te

mp

era

ture

of

90

0°C

Pow

er

turb

ine

sp

ee

d o

f 1

00 r

ev/s

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19

Ch

oic

e o

f B

ray

ton

Cy

cle

Ch

oic

e o

f B

ray

ton

Cy

cle

•C

rite

ria

Perf

orm

ance

(M

ED

IUM

)

–E

ffic

iency

Cycle

B h

ighest

Com

ponent S

ize

(LO

W)

–T

urb

o U

nits

Cycle

B low

est

Desig

n E

nve

lope

(HIG

H)

–m

ass f

low

ra

te<

20

0 k

g/s

; 2

80

<R

IT<

50

0;

pre

ssu

re r

atio

<3

.5

–A

ll B

rayto

n c

ycle

s e

xceed t

he m

ass f

low

rate

lim

itation a

t 500 M

Wt

•C

on

clu

sio

n

Cycle

B p

refe

rre

d B

rayto

n C

ycle

How

ever,

Cycle

B e

xceeds the m

ass flo

w r

ate

lim

itation (

at

500M

W)

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20

GT

CC

Co

nfi

gu

rati

on

sG

TC

C C

on

fig

ura

tio

ns

•(G

) S

ing

le-s

haft

recu

pera

tive B

rayto

n w

ith

in

ter-

co

olin

g

•(H

)* S

ing

le-s

haft

Bra

yto

n w

ith

ou

t in

ter-

co

olin

g

•(J

) S

ing

le-s

haft

recu

pera

tive B

rayto

n w

ith

ou

t in

ter-

co

olin

g

*In

dir

ec

t C

yc

le I

to

fo

llo

w l

ate

r

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21

GT

CC

Co

nfi

gu

rati

on

sG

TC

C C

on

fig

ura

tio

ns

G,

HG

, H

G:

Sin

gle

-sh

aft

recu

pera

tive B

rayto

n

wit

h i

nte

r-co

olin

g

H:

Sin

gle

-sh

aft

Bra

yto

n

wit

ho

ut

inte

r-co

oli

ng

IHX

Co

nd

en

ser

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22

GT

CC

Co

nfi

gu

rati

on

sG

TC

C C

on

fig

ura

tio

ns JJ

J:

Sin

gle

-sh

aft

recu

pera

tive B

rayto

n

wit

ho

ut

inte

r-co

oli

ng

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23

Bra

yto

n/R

an

kin

eB

ray

ton

/Ra

nk

ine

Cy

cle

Po

we

r T

rad

eo

ffC

yc

le P

ow

er

Tra

de

off

SG

SG

PB

MR

PB

MR

LP

C

LP

C

PT

PT

RE

CR

EC

pre

heat

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24

0.3

7

0.3

8

0.3

9

0.4

0

0.4

1

0.4

2

0.4

3

0.4

4

0.4

5

0.4

6

0.4

7

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

To

tal

Bra

yto

n P

ress

ure

Ra

tio

Efficiency [%]

Cycle

GC

ycle

HC

ycle

J

GT

CC

GT

CC

Net

Cycle

Eff

icie

ncy

Net

Cycle

Eff

icie

ncy

•C

ycle

H h

as h

igh

est

net

cycle

eff

icie

ncy, h

ow

ever

on

ly a

sm

all d

iffe

ren

ce e

xis

ts

betw

een

GT

CC

eff

icie

ncie

s

Resultin

g f

rom

optim

ization a

nd p

reheat

at

(G)

and (

J)

Net

eff

icie

ncy v

s. P

ressu

re r

ati

o

(G)1

-Sh

aft

RX

,IC

(H)1

-Sh

aft

(J)

1-S

ha

ft R

X

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25

250

300

350

400

450

500

550

600

650

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

To

tal

Bra

yto

n P

ress

ure

Ra

tio

RIT [C]

Cycle

GC

ycle

HC

ycle

J

GT

CC

GT

CC

RIT

RIT

•M

ax

imu

m R

IT o

f 5

00°C

; to

en

ab

le C

ore

Barr

el to

op

era

te b

elo

w 4

27°C

All

GT

CC

sare

able

to o

pera

te a

t its m

axim

um

effic

iencie

s w

ithin

the e

nvelo

pe

Reacto

r in

let

tem

pera

ture

vs. P

ressu

re r

ati

o

(G)1

-Sh

aft

RX

,IC

(H)1

-Sh

aft

(J)

1-S

ha

ft R

X

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26

120

140

160

180

200

220

240

260

280

300

320

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

To

tal

Bra

yto

n P

ress

ure

Ra

tio

Massflow Rate [kg/s]

Cycle

GC

ycle

HC

ycle

J

GT

CC

GT

CC

Mass F

low

Rate

Mass F

low

Rate

•M

ax

imu

m m

as

s f

low

of

~2

00

kg

/s;

to l

imit

re

ac

tor

co

re v

elo

cit

y

All

the G

TC

Cs

are

able

to o

pera

te a

t its m

axim

um

effic

iencie

s w

ithin

the e

nvelo

pe

Mass f

low

rate

vs. P

ressu

re r

ati

o

(G)1

-Sh

aft

RX

,IC

(H)1

-Sh

aft

(J)

1-S

ha

ft R

X

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27

50

70

90

110

130

150

170

190

210

230

250

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

To

tal

Bra

yto

n P

ress

ure

Ra

tio

Power Output [MW]G

TC

CG

TC

CW

ork

Sp

lit

Wo

rk S

pli

t

•C

ycle

H:

~80%

Ran

kin

e a

nd

20%

Bra

yto

n (

larg

e R

an

kin

e)

•C

ycle

J:

~50%

Ran

kin

e a

nd

50%

Bra

yto

n (

eq

ual sp

lit)

Fra

cti

on

of

Ran

kin

evs. T

ota

l o

utp

ut

(G)1

-Sh

aft

RX

,IC

(H)1

-Sh

aft

(J)

1-S

ha

ft R

X

Tota

l

Rankin

e-S

ection o

f (H

)

Rankin

e-S

ection o

f (

G)(

J)

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28

Ch

oic

e o

f G

TC

CC

ho

ice

of

GT

CC

•C

rite

ria

Perf

orm

ance

(ME

DIU

M)

–N

et C

ycle

Effic

iency –

•C

ycle

H –

45

.8%

,

•C

ycle

J –

45.1

%

Desig

n E

nvelo

pe

(HIG

H)

–A

ll G

TC

Cs

within

envelo

pe

Readin

ess

(HIG

H)

–C

ycle

H -

•C

om

pre

ssor

inle

t te

mpera

ture

~200°C

–n

ew

turb

o m

achin

e

desig

n (

PB

MR

DP

P 2

3°C

)

•C

oolin

g flo

w r

equired

–C

ycle

J:

•B

uild

s o

n c

urr

ent P

BM

R D

PP

Bra

yto

n d

esig

n (

layout)

•U

tiliz

es P

BM

R D

PP

heliu

m turb

o m

achin

ery

(opera

ting c

onditio

ns

sim

ilar

to D

PP

)

•C

on

clu

sio

n

Cycle

J a

nd H

both

good c

hoic

es, how

ever,

Cycle

J is p

erc

eiv

ed a

s low

est

risk d

ue to k

now

n B

rayto

n turb

o m

achin

ery

Cycle

J s

ele

cte

d a

s r

efe

rence G

TC

C

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29

Ch

oic

e o

f R

an

kin

eC

ho

ice

of

Ra

nk

ine

•E

valu

ate

d a

sin

gle

“re

pre

sen

tati

ve”

Ran

kin

e c

ycle

an

d h

en

ce

Cycle

K c

ho

sen

by d

efa

ult

Effic

iency =

42%

Prim

ary

sid

e m

ass flo

w =

160 k

g/s

(w

ithin

reacto

r desig

n

envelo

pe)

RIT

= 3

00°C

(w

ithin

reacto

r desig

n e

nvelo

pe)

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30

Part

2 O

utl

ine

Part

2 O

utl

ine

•In

tro

du

cti

on

•A

na

lys

is M

eth

od

olo

gy

•E

va

lua

tio

n

Bra

yto

n C

ycle

s

GT

CC

Ra

nkin

e C

ycle

s

•C

ycle

Tra

de-o

ffs

•S

um

ma

ry

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31

Ne

t C

yc

le E

ffic

ien

cie

sN

et

Cy

cle

Eff

icie

nc

ies

Dir

ect

Cycle

s A

, B

, C

, D

, E

, G

, H

, J, K

Dir

ect

Cycle

s A

, B

, C

, D

, E

, G

, H

, J, K

0.3

7

0.3

8

0.3

9

0.4

0

0.4

1

0.4

2

0.4

3

0.4

4

0.4

5

0.4

6

0.4

7

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

To

tal

Bra

yto

n P

ress

ure

Ra

tio

Efficiency [%]

Cycle

AC

ycle

BC

ycle

CC

ycle

DC

ycle

EC

ycle

G

Cycle

HC

ycle

JC

ycle

K

GT

CC

Rankin

e C

ycle

Bra

yto

n C

ycle

s

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32

Dir

ec

tD

ire

ct --

vs

. In

dir

ec

t C

yc

les

vs

. In

dir

ec

t C

yc

les

(F)

Ind

ire

ct

sin

gle

-sh

aft

wit

h i

nte

r-c

oo

lin

g

(In

dir

ect

vers

ion

of

Cycle

B)

(I)

Ind

ire

ct

sin

gle

-sh

aft

Bra

yto

n

(In

dir

ect

vers

ion

of

Cycle

H)

Co

nd

en

ser

(L)

Ind

irect

seco

nd

ary

ste

am

cycle

(In

dir

ect

vers

ion

of

Cycle

K)

Ind

irect

Bra

yto

nIn

dir

ect

Bra

yto

n

Ind

irect

GT

CC

Ind

irect

GT

CC

Ind

irect

Ran

kin

eIn

dir

ect

Ran

kin

e

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33

0.3

7

0.3

8

0.3

9

0.4

0

0.4

1

0.4

2

0.4

3

0.4

4

0.4

5

0.4

6

0.4

7

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

To

tal

Bra

yto

n P

ress

ure

Ra

tio

Efficiency [%]

Cycle

BC

ycle

FC

ycle

HC

ycle

IC

ycle

KC

ycle

L

Ind

ire

ct

Cy

cle

sIn

dir

ec

t C

yc

les

Net

Cycle

Eff

icie

ncy

Net

Cycle

Eff

icie

ncy

•In

dir

ect

Cycle

s r

ed

uces t

he n

et

cycle

eff

icie

ncy b

y:

Bra

yto

n C

ycle

~4%

, G

TC

C ~

2%

, R

ankin

e C

ycle

~2%

Net

cycle

eff

icie

ncy v

s. P

ressu

re r

ati

o

GT

CC

Ra

nkin

e C

ycle

s

Bra

yto

n C

ycle

s

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34H2

Series

H2

Pa

rall

el

0.3

50

0.3

60

0.3

70

0.3

80

0.3

90

0.4

00

0.4

10

0.4

20

0.4

30

0.4

40

0.4

50

050

100

150

200

Hyd

rog

en

Pla

nt

Siz

e [

MW

t]

PCS Cycle Efficiency [%]

Cycle

B -

Para

llel

Cycle

B -

Series

Co

nfi

gu

rati

on

Tra

de

Co

nfi

gu

rati

on

Tra

de

-- off

so

ffs

Bra

yto

nB

ray

ton

Seri

es v

s.

Para

llel

Seri

es v

s.

Para

llel

•E

ffect

of

H2

pla

nt

siz

e a

nd

co

nfi

gu

rati

on

on

Dir

ect

Bra

yto

n

Cycle

(B

) th

erm

al eff

icie

ncy

Ple

ase n

ote

: p

ara

llel blo

wer

house load n

ot in

clu

ded; p

ara

llelm

ixin

g n

ot in

clu

ded

Para

llel

Series

Re-o

pti

miz

ed

Pla

nts

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35

0.3

50

0.3

60

0.3

70

0.3

80

0.3

90

0.4

00

0.4

10

0.4

20

0.4

30

0.4

40

0.4

50

050

100

150

200

Hyd

rog

en

Pla

nt

Siz

e [

MW

t]

PCS Cycle Efficiency [%]

Cycle

B -

Series

Cycle

L -

Series

Co

nfi

gu

rati

on

Tra

de

Co

nfi

gu

rati

on

Tra

de

-- off

so

ffs

Infl

ue

nc

e o

f H

yd

rog

en

pla

nt

siz

eIn

flu

en

ce

of

Hy

dro

ge

n p

lan

t s

ize

•E

ffect

of

H2

pla

nt

siz

e c

ou

ple

d in

seri

es o

n t

he t

herm

al

eff

icie

ncy o

f a D

irect

Bra

yto

n C

ycle

(B

) vs.

Ran

kin

e C

ycle

(L)

Rankin

e c

ycle

effic

iency >

Bra

yto

n c

ycle

effic

iency a

bove

100 M

W h

ydro

gen p

lant

Rankin

e

Bra

yto

n

Re-o

pti

miz

ed

Pla

nts

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36

Part

2 O

utl

ine

Part

2 O

utl

ine

•In

tro

du

cti

on

•A

na

lys

is M

eth

od

olo

gy

•E

va

lua

tio

n

Bra

yto

n C

ycle

s

GT

CC

Ra

nkin

e C

ycle

s

•C

ycle

Tra

de-o

ffs

•S

um

ma

ry

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37

Su

mm

ary

Su

mm

ary

•C

ycle

B c

ho

sen

as r

efe

ren

ce B

rayto

n C

ycle

PC

S Best effic

ien

cy

Turb

o m

ach

ine g

row

th p

ath

•C

ycle

J c

ho

sen

as r

efe

ren

ce G

TC

C P

CS

Build

s o

n c

urr

ent P

BM

R D

PP

Bra

yto

n d

esig

n

•C

on

ven

tio

nal R

an

kin

e C

ycle

ch

osen

fo

r

refe

ren

ce R

an

kin

e C

ycle

PC

S

Ran

kin

e C

ycle

Ran

kin

e C

ycle

GT

CC

Cycle

GT

CC

Cycle

Bra

yto

n C

ycle

Bra

yto

n C

ycle

(B)

(J)

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APPENDIX 20.3.1: SPECIAL STUDY 20.3.1 SLIDES

PART 3 – HPU, IHX/MATERIALS, SHTS WORKING FLUID

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1

SP

EC

IAL

ST

UD

IES

:S

PE

CIA

L S

TU

DIE

S:

20

.32

0.3

--H

EA

T T

RA

NS

PO

RT

SY

ST

EM

H

EA

T T

RA

NS

PO

RT

SY

ST

EM

20

.42

0.4

--P

OW

ER

CO

NV

ER

SIO

N S

YS

TE

M

PO

WE

R C

ON

VE

RS

ION

SY

ST

EM

Pa

rt 3

P

art

3 ––

HP

U, IH

X/M

ate

rials

, S

HT

S W

ork

ing

Flu

idH

PU

, IH

X/M

ate

rials

, S

HT

S W

ork

ing

Flu

id

De

ce

mb

er

6,

20

06

De

ce

mb

er

6,

20

06

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2

Ou

tlin

eO

utl

ine

•O

bje

cti

ve a

nd

Sco

pe

•S

tud

y In

pu

tsC

om

merc

ial applic

ations a

nd p

erf

orm

ance r

equirem

ents

Key N

GN

P H

TS

dem

onstr

ation o

bje

ctives

Key H

TS

functional re

quirem

ents

•S

cre

en

ing

Cri

teri

a

•P

ow

er

Co

nvers

ion

Syste

m O

pti

on

s (

20.4

)

•H

2P

rod

ucti

on

Un

it S

ize (

20.7

)

•IH

X/H

igh

-Tem

pera

ture

Mate

rials

•S

eco

nd

ary

Wo

rkin

g F

luid

•H

TS

Co

nfi

gu

rati

on

Op

tio

ns

•R

eco

mm

en

ded

HT

S C

on

fig

ura

tio

n

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3

HH22

Pro

du

cti

on

Un

it (

HP

U)

Siz

e:

Pro

du

cti

on

Un

it (

HP

U)

Siz

e:

Inp

ut

fro

m S

pecia

l S

tud

y 2

0.7

Inp

ut

fro

m S

pecia

l S

tud

y 2

0.7

•M

inim

um

siz

e t

hat

wo

uld

allo

w s

cale

-up

of

mo

st

cri

tical

co

mp

on

en

t to

co

mm

erc

ial

siz

e

~5M

Wt

•S

cale

of

sin

gle

tra

in o

f co

mm

erc

ial

HP

U

~50M

Wt

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006

4

Ou

tlin

eO

utl

ine

•O

bje

cti

ve a

nd

Sco

pe

•S

tud

y In

pu

tsC

om

merc

ial applic

ations a

nd p

erf

orm

ance r

equirem

ents

Key N

GN

P H

TS

dem

onstr

ation o

bje

ctives

Key H

TS

functional re

quirem

ents

•S

cre

en

ing

Cri

teri

a

•P

ow

er

Co

nvers

ion

Syste

m O

pti

on

s (

20.4

)

•H

2P

rod

ucti

on

Un

it S

ize (

20.7

)

•IH

X/H

igh

-Tem

pera

ture

Mate

rials

•S

eco

nd

ary

Wo

rkin

g F

luid

•H

TS

Co

nfi

gu

rati

on

Op

tio

ns

•R

eco

mm

en

ded

HT

S C

on

fig

ura

tio

n

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5

Intr

od

uc

tio

nIn

tro

du

cti

on

•T

he I

HX

rep

resen

ts o

ne o

f th

e m

ost

sig

nif

ican

t

de

ve

lop

me

nt

ch

all

en

ge

s a

ss

oc

iate

d w

ith

th

e N

GN

P a

nd

rela

ted

co

mm

erc

ial

pro

cess h

eat

pla

nts

•A

s e

arl

ier

no

ted

, th

e I

HX

is a

key d

em

on

str

ati

on

ob

jecti

ve

of

the

NG

NP

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3-R

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6

Ou

tlin

eO

utl

ine

IHX

/Hig

hIH

X/H

igh

-- Tem

pe

ratu

re M

ate

rials

T

em

pera

ture

Mate

rials

•In

tro

du

cti

on

•IH

X F

un

cti

on

s a

nd

Req

uir

em

en

ts

•IH

X D

esig

n O

pti

on

s

•R

ead

iness o

f C

an

did

ate

Mate

rials

•C

od

es a

nd

Sta

nd

ard

s R

ead

iness

•C

on

clu

sio

ns

an

d R

ec

om

me

nd

ati

on

s f

or

NG

NP

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7

IHX

Fu

ncti

on

sIH

X F

un

cti

on

s

•T

ran

sfe

r th

erm

al

en

erg

y p

rod

uced

in

th

e r

eacto

r fr

om

th

e

heliu

m p

rim

ary

co

ola

nt

to t

he s

eco

nd

ary

heat

tran

sp

ort

syste

m (

SH

TS

) fl

uid

Du

rin

g n

orm

al o

pe

ratio

na

l m

od

es in

wh

ich

th

e t

he

rma

l energ

y is u

tiliz

ed in t

he p

rocess

For

desig

nate

d e

vents

within

the d

uty

cycle

, w

here

in

reacto

r heat (r

educed p

ow

er

or

decay h

eat)

is to b

e

transport

ed t

o a

n a

ltern

ate

heat

sin

k,

either

in t

he S

HT

S o

r th

e p

rocess

•C

on

tain

th

e h

eli

um

pri

ma

ry c

oo

lan

t a

nd

th

e S

HT

S w

ork

ing

flu

id

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8

Key P

BM

R N

GN

P IH

X R

eq

uir

em

en

tsK

ey P

BM

R N

GN

P IH

X R

eq

uir

em

en

ts

5 –

50

Fro

m S

pe

cia

l S

tud

y 2

0.7

510

Th

erm

al

Rati

ng

, M

Wt

9.0

9.0

PH

TS

Pre

ssu

re,

MP

a

Ap

pli

ca

tio

n S

pe

cif

ic290

Se

co

nd

ary

In

let

Te

mp

, ºC

900-9

25

900-9

25

Seco

nd

ary

Ou

tlet

Tem

p,

ºC

950

950

Pri

mary

Ou

tle

t T

em

p,

ºC

Based

on

th

erm

al

rati

ng

[938 -

710]

340

Pri

mary

In

let

Te

mp

, ºC

He

liu

m*

He

liu

m*

SH

TS

Wo

rkin

g F

luid

9.0

9.0

SH

TS

Pre

ssu

re,

MP

a

HP

U O

nly

HP

U a

nd

PG

S+

Co

nfi

gu

rati

on

+ E

ssentially

equiv

ale

nt to

com

merc

ial pla

nt IH

X

*P

relim

inary

sele

ction, based o

n p

rior

work

-to

be c

onfirm

ed

Additio

nal R

equirem

ents

for

Co

mm

erc

ial P

lants

(P

relim

inary

):[R

ef. 4

]

Desig

n L

ife (

Min

imum

):20yrs

Forc

ed O

uta

ge A

llocation:

~<

1%

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9

Te

st

Pla

teT

es

t P

late

-- Fin

HX

at

10

00

CF

in H

X a

t 1

00

0C

(Cou

rtesy C

.F. M

cD

ona

ld)

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10

Ou

tlin

eO

utl

ine

IHX

/Hig

hIH

X/H

igh

-- Te

mp

era

ture

Ma

teri

als

Te

mp

era

ture

Ma

teri

als

•In

tro

du

cti

on

•IH

X F

un

cti

on

s a

nd

Req

uir

em

en

ts

•IH

X D

esig

n O

pti

on

s

•R

ead

iness o

f C

an

did

ate

Mate

rials

•C

od

es a

nd

Sta

nd

ard

s R

ead

iness

•C

on

clu

sio

ns

an

d R

ec

om

me

nd

ati

on

s f

or

NG

NP

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11

Tu

be a

nd

Sh

ell

Tu

be a

nd

Sh

ell H

Xs

HX

s

Se

con

da

ry h

eliu

m

(to

SP

WC

)

Se

con

da

ry h

eliu

m

(fro

m S

PW

C)

Prim

ary

he

lium

(fro

m r

ea

cto

r)

Prim

ary

he

lium

(to

re

acto

r)

Prim

ary

he

lium

(to

HG

C)

Prim

ary

he

lium

(fro

m H

GC

)

: P

rim

ary

he

lium

Se

con

da

ry H

e

Inle

t n

ozzle

Ma

nh

ole

Tu

be s

up

po

rt

asse

mb

ly

Ce

ntr

al ho

t

ga

s d

uct

(Ce

nte

r p

ipe

)

Ho

t h

ea

de

r

He

lica

lly-c

oile

d

he

at tr

an

sfe

r tu

be

Th

erm

al

insu

lation

Oute

r sh

ell

Inn

er

sh

ell

Co

ld h

ead

er

Se

con

da

ry h

eliu

m

do

ub

le n

ozzle

: S

econ

da

ry

he

lium

Se

con

da

ry h

eliu

m

(to

SP

WC

)

Se

con

da

ry h

eliu

m

(fro

m S

PW

C)

Prim

ary

he

lium

(fro

m r

ea

cto

r)

Prim

ary

he

lium

(to

re

acto

r)

Prim

ary

he

lium

(to

HG

C)

Prim

ary

he

lium

(fro

m H

GC

)

: P

rim

ary

he

lium

: P

rim

ary

he

lium

Se

con

da

ry H

e

Inle

t n

ozzle

Ma

nh

ole

Tu

be s

up

po

rt

asse

mb

ly

Ce

ntr

al ho

t

ga

s d

uct

(Ce

nte

r p

ipe

)

Ho

t h

ea

de

r

He

lica

lly-c

oile

d

he

at tr

an

sfe

r tu

be

Th

erm

al

insu

lation

Oute

r sh

ell

Inn

er

sh

ell

Co

ld h

ead

er

Se

con

da

ry h

eliu

m

do

ub

le n

ozzle

: S

econ

da

ry

he

lium

: S

econ

da

ry

he

lium

HT

TR

Helical C

oil IH

X

Suppo

rt

Bra

ckets

Tubes

Sh

ell

Baff

les

End B

onne

t

Tubesheet

Suppo

rt

Bra

ckets

Tubes

Sh

ell

Baff

les

End B

onne

t

Tubesheet

(Pho

to F

rom

AP

I H

ea

t T

ransfe

r)

Str

aig

ht-

Tu

be H

X

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12

Pla

teP

late

-- Fin

HX

Fin

HX

(In

gers

oll R

an

d E

nerg

y S

yste

ms)

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13

Pri

nte

d C

irc

uit

He

at

Ex

ch

an

ge

r P

rin

ted

Cir

cu

it H

ea

t E

xc

ha

ng

er

(PC

HE

)(P

CH

E)

(Heatr

ic)

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14

He

at

Ex

ch

an

ge

r M

etr

ics

He

at

Ex

ch

an

ge

r M

etr

ics

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15

De

sig

n T

rad

eo

ffs

De

sig

n T

rad

eo

ffs

Mo

re d

iffi

cu

lt H

X in

teg

rati

on

wit

h m

ult

iple

seri

es/p

ara

lle

l

mo

du

les

Mo

re d

iffi

cu

lt H

X in

teg

rati

on

wit

h m

ult

iple

seri

es/p

ara

lle

l

mo

du

les

Head

ers

an

d H

X-v

essel

inte

gra

tio

n d

em

on

str

ate

dH

X I

nte

gra

tio

n

No

ex

isti

ng

Co

de b

asis

No

ex

isti

ng

Co

de b

asis

Ex

isti

ng

Sect

VIII C

od

e b

asis

for

tub

ula

r g

eo

metr

ies

Co

de B

asis

fo

r D

esig

n

Insp

ecti

on

an

d m

ain

ten

an

ce

dif

ficu

lt o

r im

pra

cti

cal b

elo

w

mo

du

le le

ve

l

Insp

ecti

on

an

d m

ain

ten

an

ce

dif

ficu

lt o

r im

pra

cti

cal b

elo

w

mo

du

le le

ve

l

Desig

n f

acilit

ate

s in

sp

ec

tio

n

an

d p

lug

gin

g o

f in

div

idu

al

tub

es

Ins

pe

cti

on

an

d

Ma

inte

na

nc

e

* R

efe

ren

ce 5

Go

od

: T

hic

ker

pla

tes;

local

de

bo

nd

ing

do

es n

ot

imm

ed

iate

ly a

ffect

pre

ssu

re

bo

un

da

ry;

po

ten

tia

l fo

r

hig

her

tra

nsie

nt

therm

al

str

esses v

s. P

-F

Wo

rst:

Th

in f

oil

s;

str

essed

weld

s in

pre

ssu

re b

ou

nd

ary

;

str

ess r

isers

in

pre

ssu

re

bo

un

dary

we

lds;

Sm

all

ma

teri

al a

nd

weld

de

fects

mo

re s

ign

ific

an

t

Best:

Sim

ple

cylin

dri

ca

l

geo

metr

y, str

ess m

inim

ized

in H

T a

rea

Ro

bu

stn

es

s

PB

MR

DP

P R

ecu

pera

tor,

oth

er

co

mm

erc

ial p

rod

ucts

Co

nven

tio

nal G

T

rec

up

era

tors

HT

TR

, G

erm

an

PN

P

De

ve

lop

me

nt

Exp

eri

en

ce B

ase

Go

od

: (0

.2 t

on

s/M

Wt)

*

Es

tim

ate

d t

o b

e ~

1/6

8 t

hat

of

S&

T

Best:

Mo

st

co

mp

ac

t, least

mate

rials

Po

or:

(13.5

to

ns/M

Wt)

*

Un

likely

to

be

co

mm

erc

ially

via

ble

Co

st

(t/M

Wt)

Go

od

Best

Po

or

Co

mp

actn

ess

(m2/m

3&

MW

/m3)

PC

HE

Pla

te-F

in &

Pri

me

Su

rfa

ce

Sh

ell &

Tu

be

Metr

ic

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Pre

lim

ina

ry D

es

ign

Se

lec

tio

nP

reli

min

ary

De

sig

n S

ele

cti

on

PC

HE

sele

cte

d a

s p

relim

inary

basis

fo

r N

GN

P IH

X:

•S

hell &

tu

be (

S&

T)

elim

inate

d a

s n

ot

co

mm

erc

ially v

iab

le

for

larg

e IH

X

•P

CH

E j

ud

ge

d t

o b

e m

ore

ro

bu

st

tha

n o

the

r c

om

pa

ct

de

sig

ns

So

lid b

asis

of

co

mm

erc

ial e

xp

erie

nce

, a

lbe

it a

t lo

we

r te

mpera

ture

s

•T

rad

eo

ffs

vs

. S

&T

in

clu

de

:

More

difficult inspection a

nd m

ain

tenance

Ne

ed

to

esta

blis

h d

esig

n b

asis

fo

r C

od

e a

cce

pta

nce

(a

dd

itio

na

l d

iscu

ssio

n f

ollo

ws)

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17

Ou

tlin

eO

utl

ine

IHX

/Hig

hIH

X/H

igh

-- Te

mp

era

ture

Ma

teri

als

Te

mp

era

ture

Ma

teri

als

•In

tro

du

cti

on

•IH

X F

un

cti

on

s a

nd

Req

uir

em

en

ts

•IH

X D

esig

n O

pti

on

s

•R

ead

iness o

f C

an

did

ate

Mate

rials

•C

od

es a

nd

Sta

nd

ard

s R

ead

iness

•C

on

clu

sio

ns

an

d R

ec

om

me

nd

ati

on

s f

or

NG

NP

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18

Lead

ing

Can

did

ate

Meta

llic

Mate

rials

fo

r IH

X

Lead

ing

Can

did

ate

Meta

llic

Mate

rials

fo

r IH

X

•C

an

did

ate

me

tall

ic m

ate

ria

ls (

~3

0)

ide

nti

fie

d i

n N

GN

P M

ate

ria

ls R

&D

P

rog

ram

Pla

n [R

ef.

6]

•F

urt

her

evalu

ati

on

has i

den

tifi

ed

fo

ur

lead

ing

can

did

ate

s t

hat

sh

ou

ld b

e

giv

en

fu

rth

er

co

nsid

era

tio

n:

Inconel617C

CA

*

Haynes 2

30 (

a m

ain

focus o

f E

U H

TG

R m

ate

rials

develo

pm

ent)

Haynes 5

56

HR

-120

•O

the

r a

dv

an

ced

me

tall

ic m

ate

ria

ls (

e.g

., O

xid

e D

isp

ers

ion

Str

en

gth

en

ed

[O

DS

]) p

ote

nti

ally h

ave h

igh

er

tem

pera

ture

cap

ab

ilit

y, b

ut

are

no

t p

racti

cal

alt

ern

ati

ve

s i

n t

ime

fra

me

of

NG

NP

For

OD

S, no p

ractical m

anufa

ctu

ring t

echnolo

gie

s e

xis

t th

at do n

ot degra

de

mate

rial pro

pert

ies

*M

ore

tig

htl

y c

on

tro

lle

d I

-61

7 s

pe

cif

ica

tio

n d

ev

elo

pe

d w

ith

in t

he

U

ltra

su

perc

riti

cal

Fo

ssil P

rog

ram

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19

Me

tall

ic M

ate

ria

ls O

ve

rvie

wM

eta

llic

Ma

teri

als

Ov

erv

iew

Allo

wa

ble

Str

es

s In

ten

sit

y (

Sm

t) IH

X M

ate

ria

ls

0

50

10

0

15

0

20

0

25

0 50

06

00

70

08

00

90

01

00

01

10

0

Te

mp

era

ture

(C

)

Stress Intensity (MPa)

Allo

yX

I-6

17

80

0H

H-2

30

H-5

56

HR

-12

0

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20

Marg

inal d

esig

n p

rop

ert

ies a

t h

igh

est

tem

pera

ture

s o

f

inte

res

t.

No

te f

all

-off

of

Ha

yn

es

23

0 a

t h

igh

es

t te

mp

era

ture

s

Cre

ep

da

ta f

or

I-6

17

& H

-23

0(D

ata

fro

m IN

CO

& H

ay

ne

s)

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21

Pro

s a

nd

Co

ns o

f P

ros a

nd

Co

ns o

f

Meta

llic

Mate

rials

Can

did

ate

sM

eta

llic

Mate

rials

Can

did

ate

s

•In

co

nel

617

Pro

s:

Best H

T m

echanic

al pro

pert

ies; sig

nific

ant heliu

m d

ata

base in G

erm

any

(bu

t a

cce

ss t

o G

erm

an

da

ta u

nce

rta

in)

Cons:H

igh C

o; gre

ate

r susceptibili

ty to inte

rnal oxid

ation; w

ide s

pecific

ation

range leads to inconsis

tent pro

pert

ies

•H

ayn

es 2

30

Pro

s:

Low

Co;

more

corr

osio

n r

esis

tant

than I

-617;

focus o

f E

U d

evelo

pm

ent

Cons:H

igh W

, m

echanic

al pro

pert

ies fall

off in h

ighest te

mpera

ture

regio

ns

•H

ayn

es 5

56

Pro

s:

Second b

est H

T m

echanic

al pro

pert

ies; hig

hest carb

urization

resis

tance

Cons:H

igh C

o; no e

xperience in h

eliu

m, im

plie

s incre

ased R

&D

needs

•H

R-1

20

Pro

s:

Lo

w C

o

Cons:Less s

tabili

ty a

t hig

h t

em

pera

ture

; no e

xperience in h

eliu

m,

implie

sin

cre

ased R

&D

needs

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Me

tall

ic M

ate

ria

ls S

um

ma

ryM

eta

llic

Ma

teri

als

Su

mm

ary

•E

xis

tin

g m

eta

llic

mate

rials

can

be a

pp

lied

in

tem

pera

ture

reg

ime o

f N

GN

P IH

X, alb

eit

wit

h s

ign

ific

an

t lim

itati

on

s:

Will

re

qu

ire

de

sig

ns b

ase

d o

n v

ery

lo

w s

tre

sse

s d

urin

g

norm

al lo

ng-t

erm

opera

tion

Tra

nsie

nt-

rela

ted

str

esse

s w

ill b

e m

ore

sig

nific

an

t in

com

pact IH

Xs (

needs furt

her

evalu

ation)

Lik

ely

ne

ed

to

re

pla

ce

IH

X c

ore

mu

ltip

le tim

es o

ve

r

60-y

ear

desig

n life o

f pla

nt

•P

resen

t m

eta

llic

mate

rials

are

lik

ely

no

t th

e o

pti

mu

m

lon

g-t

erm

so

luti

on

fo

r co

mm

erc

ial

pro

cess h

eat

pla

nts

op

era

tin

g in

th

e N

GN

P t

em

pera

ture

ran

ge

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Ce

ram

ic H

X C

on

ce

pts

Ce

ram

ic H

X C

on

ce

pts

Un

it c

ell o

f o

ffset-

fin

Liq

uid

Si

Inje

cte

dco

mp

osit

e p

late

HX

(UC

Berk

ley)

SiC

HX

Co

ncep

t(C

era

mate

c)

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24

Ce

ram

ic M

ate

ria

ls S

um

ma

ryC

era

mic

Ma

teri

als

Su

mm

ary

•C

era

mic

mate

rials

pre

sen

tly b

ein

g e

valu

ate

d a

re:

Monolit

hic

SiC

Com

posites, such a

s c

arb

on fib

er

rein

forc

ed c

om

posites w

ith liq

uid

Si

inje

ction

•C

hallen

gin

g d

evelo

pm

en

t is

su

es

Develo

pm

ent of re

liable

, cost effective H

X d

esig

n a

nd a

ssocia

ted

fabrication t

echnolo

gie

s

Cera

mic

-meta

llic inte

rfaces m

ust als

o b

e a

ddre

ssed

No C

ode b

asis

exis

ts fo

r th

e u

se o

f cera

mic

mate

rials

in p

ressure

boundary

applic

ations

•C

era

mic

IH

Xs a

re u

nlikely

to

be a

vailab

le i

n a

tim

efr

am

e t

ha

t w

ou

ld

su

pp

ort

in

itia

l N

GN

P d

ep

loym

en

t

But, h

igh incentives f

or

ultim

ate

dem

onstr

ation o

f a I

HX

based o

n c

era

mic

s

(or

oth

er

advanced m

ate

rial)

Giv

en their im

port

ance, cera

mic

HX

develo

pm

ent deserv

es a

ccele

rate

d

effort

in p

ara

llel w

ith m

eta

llic o

ptions

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25

Ou

tlin

eO

utl

ine

IHX

/Hig

hIH

X/H

igh

-- Te

mp

era

ture

Ma

teri

als

Te

mp

era

ture

Ma

teri

als

•In

tro

du

cti

on

•IH

X F

un

cti

on

s a

nd

Req

uir

em

en

ts

•IH

X D

esig

n O

pti

on

s

•R

ead

iness o

f C

an

did

ate

Mate

rials

•C

od

es a

nd

Sta

nd

ard

s R

ead

iness

•C

on

clu

sio

ns

an

d R

ec

om

me

nd

ati

on

s f

or

NG

NP

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26

Co

de

s a

nd

Sta

nd

ard

s R

ea

din

es

sC

od

es

an

d S

tan

da

rds

Re

ad

ine

ss

•M

eta

l a

llo

ys

th

at

co

uld

po

ten

tia

lly

be

us

ed

to

co

ns

tru

ct

the

IH

Xare

no

t c

urr

en

tly

a p

art

of

the

AS

ME

Nu

cle

ar

Co

de

, S

ec

tio

n I

II

A s

ignific

ant effort

will

be r

equired to r

esolv

e this

issue b

ecause a

relia

ble

data

base p

ote

ntially

usefu

l fo

r a c

ode c

ase b

ased o

n thre

e w

ell-

docum

ente

d h

eats

of m

ate

rial is

not availa

ble

•T

he

re i

s n

o e

xis

tin

g A

SM

E C

od

e b

as

is (

Se

cti

on

III

or

oth

er)

fo

r th

e

ap

plicati

on

of

cera

mic

s in

pre

ssu

re b

ou

nd

ary

ap

plicati

on

s

•T

here

is n

o e

xis

tin

g A

SM

E S

ecti

on

III d

esig

n b

asis

fo

r eit

her

a

co

nven

tio

nal

tub

e a

nd

sh

ell I

HX

or

less c

on

ven

tio

nal

pla

te-t

yp

e I

HX

•T

he m

ost

exp

ed

ien

t ap

pro

ach

fo

r th

e N

GN

P I

HX

ap

pears

to

be

develo

pm

en

t o

f an

ap

plicati

on

-sp

ecif

ic d

esig

n b

asis

an

d s

ub

mit

tal o

f a

Secti

on

III c

od

e c

ase a

sso

cia

ted

wit

h S

ub

secti

on

NH

A s

ignific

ant effort

will

als

o b

e r

equired to r

esolv

e this

issue

because a

n

openly

availa

ble

desig

n b

asis

is n

ot availa

ble

in a

form

at suitable

for

a

code c

ase

•If

a p

late

-ty

pe

IH

X i

s s

ele

cte

d,

tes

tin

g o

f p

roto

typ

e I

HX

un

its

wo

uld

be

n

eed

ed

to

su

pp

ort

th

e c

od

e c

ase d

esig

n b

asis

fo

r th

e s

pecif

ic I

HX

desig

n

sele

cte

d

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Ou

tlin

eO

utl

ine

IHX

/Hig

hIH

X/H

igh

-- Te

mp

era

ture

Ma

teri

als

Te

mp

era

ture

Ma

teri

als

•In

tro

du

cti

on

•IH

X F

un

cti

on

s a

nd

Req

uir

em

en

ts

•IH

X D

esig

n O

pti

on

s

•R

ead

iness o

f C

an

did

ate

Mate

rials

•C

od

es a

nd

Sta

nd

ard

s R

ead

iness

•C

on

clu

sio

ns

an

d R

ec

om

me

nd

ati

on

s f

or

NG

NP

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28

Reco

mm

en

dati

on

s f

or

NG

NP

Reco

mm

en

dati

on

s f

or

NG

NP

IHX

De

sig

nIH

X D

es

ign

•T

he r

efe

ren

ce IH

X f

or

NG

NP

pre

co

ncep

tual d

esig

n s

ho

uld

be a

PC

HE

uti

lizin

g o

ne o

f th

e f

ou

r earl

ier

iden

tifi

ed

meta

llic

all

oys

I-617 a

nd H

aynes 2

30 a

re leadin

g c

andid

ate

s, based o

n r

educed

R&

D n

eeds

•If

a larg

e IH

X is

ap

plied

, it

th

e H

X s

ho

uld

be d

esig

ned

to

all

ow

rep

lacem

en

t o

f th

e h

igh

est

tem

pera

ture

secti

on

, in

dep

en

den

t o

f

the r

em

ain

der

of

the IH

X (

see f

ollo

win

g f

igu

re)

•T

he IH

X c

ore

sh

ou

ld b

e c

on

tain

ed

wit

hin

a p

ressu

re v

essel(

s)

that

is d

esig

ned

to

AS

ME

Secti

on

III, S

ub

secti

on

NB

(n

o c

reep

) an

d

sh

ou

ld b

e in

su

late

d a

nd

co

ole

d a

s r

eq

uir

ed

•T

he f

un

cti

on

s a

nd

req

uir

em

en

ts o

f th

e IH

X h

eat

tran

sfe

r su

rface

wit

h r

esp

ect

to c

on

tro

l o

f ra

dio

nu

clid

e r

ele

ase s

ho

uld

be f

urt

her

evalu

ate

d

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29

La

rge

, 2

La

rge

, 2

-- Se

cti

on

IH

XS

ec

tio

n IH

X

A t

wo

-se

cti

on

IH

X,

wh

ich

ap

pli

es

d

iffe

ren

t m

ate

ria

ls i

n e

ac

h s

ec

tio

n

may p

rovid

e a

n a

ccep

tab

le

so

luti

on

2-S

ection IH

X a

pplie

s c

era

mic

or

com

posite m

ate

rials

in h

igh-

tem

pera

ture

section,

meta

l in

lo

wer

tem

pera

ture

are

as

Pote

ntial to

sta

rt w

ith m

eta

l in

hig

h-t

em

pera

ture

section (

short

lif

etim

e)

and t

hen r

epla

ce w

ith

cera

mic

/com

posite w

hen r

eady

Pote

ntial to

opera

te a

t ~

850ºC

without

hig

h t

em

pera

ture

section

and then a

dd late

r

Imp

acts

of

tra

nsie

nt

eve

nts

ne

ed

to

be a

ssessed

PB

MR

Meta

l

IHX

Meta

lo

rS

iCIH

X

~950ºC~

850ºC

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30

Reco

mm

en

dati

on

s f

or

NG

NP

Reco

mm

en

dati

on

s f

or

NG

NP

Develo

pm

en

tD

evelo

pm

en

t

•A

n a

pp

rop

riate

desig

n a

nd

mate

rials

develo

pm

en

t p

rog

ram

sh

ou

ld b

e p

urs

ue

d f

or

the

IH

X

Th

e d

eve

lop

me

nt

pro

gra

m s

ho

uld

in

clu

de

fa

brica

tio

n a

nd

testing o

f re

pre

senta

tive IH

X m

odule

s in a

heat tr

ansfe

r te

st

facili

ty (

mo

difie

d P

BM

R H

eliu

m T

est

Fa

cili

ty p

ote

ntia

l option)

•B

ased

on

th

e a

bo

ve,

a s

ho

rter

term

targ

et

sh

ou

ld b

e

de

ve

lop

me

nt

of

on

e o

r m

ore

co

de

ca

se

s t

ha

t p

rov

ide

an

AS

ME

basis

fo

r th

e m

ate

rials

, d

esig

n a

nd

fab

ricati

on

of

the

NG

NP

IH

X

•A

lo

ng

er

term

targ

et

sh

ou

ld b

e r

evis

ion

of

Su

bsecti

on

NH

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31

IHX

/Ma

teri

als

Re

fere

nc

es

IHX

/Ma

teri

als

Re

fere

nc

es

1.

Lah

od

a, E

.J., e

t.al., “E

sti

mate

d C

osts

fo

r th

e Im

pro

ved

HyS

Flo

wsh

eet”

, H

TR

2006,

Octo

ber

2006.

2.

H2-M

HR

Co

ncep

tual D

esig

n R

ep

ort

: S

I-B

ased

Pla

nt

(GA

-A25401),

Gen

era

l A

tom

ics,

Ap

ril

2006.

3.

H2-M

HR

Co

ncep

tual D

esig

n R

ep

ort

: H

TE

-Based

Pla

nt

(GA

-A25402),

Gen

era

l A

tom

ics,

Ap

ril

2006.

4.

IHX

In

form

ati

on

Need

s,

PB

MR

, D

ecem

ber

2005.

5.

Dew

so

n, 2003, (T

he D

evelo

pm

en

t o

f H

igh

Eff

icie

ncy H

eat

Exch

an

gers

fo

r H

eliu

m

Gas C

oo

led

Reacto

rs),

Pap

er

3213,

ICA

PP

.

6.

Ha

yn

er

et

al, 2

006 (

NG

NP

Mate

rials

R&

D P

rog

ram

Pla

n),

IN

L/E

XT

-06-1

1701, A

ug

ust

2006.

7.

K.

Nate

san

, A

. M

ois

seyts

ev,

S.

Maju

md

ar

an

d P

. S

. S

han

kar,

“P

relim

inary

Issu

es

Asso

cia

ted

wit

h t

he N

GN

P I

HX

Desig

n”,

AN

L/E

XT

-06-4

6,

Sep

tem

ber

2006.

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32

Ou

tlin

eO

utl

ine

•O

bje

cti

ve a

nd

Sco

pe

•S

tud

y In

pu

tsC

om

merc

ial applic

ations a

nd p

erf

orm

ance r

equirem

ents

Key N

GN

P H

TS

dem

onstr

ation o

bje

ctives

Key H

TS

functional re

quirem

ents

•S

cre

en

ing

Cri

teri

a

•P

ow

er

Co

nvers

ion

Syste

m O

pti

on

s (

20.4

)

•H

2P

rod

ucti

on

Un

it S

ize (

20.7

)

•IH

X/H

igh

-Tem

pera

ture

Mate

rials

•S

eco

nd

ary

Wo

rkin

g F

luid

•H

TS

Co

nfi

gu

rati

on

Op

tio

ns

•R

eco

mm

en

ded

HT

S C

on

fig

ura

tio

n

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33

Ou

tlin

eO

utl

ine

Seco

nd

ary

Wo

rkin

g F

luid

Seco

nd

ary

Wo

rkin

g F

luid

•In

tro

du

cti

on

•K

ey F

un

cti

on

s &

Req

uir

em

en

ts

•O

ve

rvie

w o

f C

oo

lan

t P

rop

ert

ies

•C

om

pari

so

n o

f O

pti

on

s

•S

um

mary

& R

eco

mm

en

dati

on

s

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34

Intr

od

uc

tio

nIn

tro

du

cti

on

•C

om

merc

ial P

HP

ap

plicati

on

s a

nd

th

e N

GN

P r

eq

uir

e t

ran

sp

ort

of

hig

h t

em

pera

ture

th

erm

al en

erg

y f

rom

th

e n

ucle

ar

heat

so

urc

e t

o

the

po

int

of

us

e

Pre

sently 1

00m

for

HyS

for

nom

inal re

fere

nce [R

ef.1]

•P

rio

r S

HT

S w

ork

ing

flu

id e

valu

ati

on

resu

lted

in

sele

cti

on

of

he

liu

m f

or

PB

MR

PH

P

•F

or

the N

GN

P, th

e s

eco

nd

ary

heat

tran

sp

ort

syste

m (

SH

TS

)

wo

rkin

g f

luid

sele

cti

on

will

infl

uen

ce b

oth

th

e c

on

fig

ura

tio

n a

nd

Hyd

rog

en

Pro

du

cti

on

Un

it (

HP

U)

desig

ns

Key c

om

ponents

: IH

X,

Pro

cess C

ouplin

g H

eat

Exchanger

(PC

HX

)

Candid

ate

flu

ids inclu

de h

eliu

m,

CO

2, liq

uid

salts a

nd liq

uid

meta

ls

Ref.1:

Sm

ith,

C., S

. B

eck,

and B

. G

aly

ean, 2005,

“An E

ngin

eering A

naly

sis

for

Separa

tion

Requirem

ents

of

a H

ydro

gen P

roduction P

lant

and H

igh-T

em

pera

ture

Nucle

ar

Reacto

r”,

INL/E

XT

-05-0

0137 R

ev 0

, M

arc

h 2

005.

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Se

co

nd

ary

Co

ola

nt

Op

tio

ns

Se

co

nd

ary

Co

ola

nt

Op

tio

ns

•H

eliu

m Experience b

ase w

ith H

TG

Rs

Chem

ically

inert

Hig

hest

conductivity o

f candid

ate

gases

sm

alle

r heat exchangers

•C

O2

Experience b

ase w

ith M

agnox/A

GR

s

Pote

ntially

reduces p

um

pin

g p

ow

er

requirem

ents

, cost re

lative to

heliu

m

•L

iqu

id S

alt

(L

S)

Prior

nucle

ar

experience a

t hig

h t

em

pera

ture

s (

MS

RE

, A

TR

)

–M

olten

Sa

lt R

eacto

r E

xpe

rim

en

t/M

olten S

alt B

reeder

Reacto

r (M

SR

E/M

SB

R)

–A

ircra

ft R

eacto

r E

xperim

ent/A

ircra

ft R

eacto

r T

est (A

RE

/AR

T)

Industr

ial experience, but w

ith d

iffe

rent com

pounds in b

ath

s v

s.

loops

Feasib

ility

esta

blis

hed

Tem

pera

ture

range o

f applic

abili

ty b

ounded b

y m

eltin

g/b

oili

ng p

oin

ts

•L

iqu

id M

eta

l

No e

xperience in t

em

pera

ture

range o

f in

tere

st

Mate

rials

com

patibili

ty a

t hig

h t

em

pera

ture

s p

roble

matical per

OR

NL

Tem

pera

ture

range o

f applic

abili

ty b

ounded b

y m

eltin

g/b

oili

ng p

oin

t

•T

his

NG

NP

ev

alu

ati

on

fo

cu

se

d o

n h

eli

um

, C

O2

an

d L

S

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36

Ov

erv

iew

of

Tra

de

off

sO

ve

rvie

w o

f T

rad

eo

ffs

•P

erf

orm

an

ce

Volu

metr

ic h

eat

capacity (

Cp

) a

nd

vis

cosity (

) in

fluence p

um

pin

g p

ow

er

Therm

al conductivity (

k)

influences h

eat exchanger

siz

e

•C

om

po

nen

ts

Desig

n c

onsid

era

tions

Mate

rials

adequacy a

nd c

om

patibili

ty

•O

pera

tio

nal

Implic

ations f

or

duty

cycle

•A

va

ila

bil

ity

, R

eli

ab

ilit

y &

In

ve

stm

en

t P

rote

cti

on

Pro

babili

ty o

f fa

ilure

s

Failu

re m

odes a

nd e

ffects

•R

&D

Req

uir

em

en

ts

•E

co

no

mic

s

Siz

e a

nd c

ost

Pum

pin

g p

ow

er

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37

Ou

tlin

eO

utl

ine

Seco

nd

ary

Wo

rkin

g F

luid

Seco

nd

ary

Wo

rkin

g F

luid

•In

tro

du

cti

on

•K

ey F

un

cti

on

s &

Req

uir

em

en

ts

•O

ve

rvie

w o

f C

oo

lan

t P

rop

ert

ies

•C

om

pari

so

n o

f O

pti

on

s

•S

um

mary

& R

eco

mm

en

dati

on

s

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38

SH

TS

Fu

ncti

on

sS

HT

S F

un

cti

on

s

•P

rin

cip

al F

un

cti

on

s

During o

pera

tional m

odes in w

hic

h the therm

al energ

y p

roduced in

the n

ucle

ar

reacto

r

is u

tiliz

ed in the p

rocess, tr

ansport

therm

al energ

y p

roduced in

the r

eacto

r fr

om

the

IHX

to the p

rocess c

ouplin

g h

eat exchanger

(PC

HX

)

Conta

in the s

econdary

flu

id d

uring a

ll opera

tional m

odes

•P

ote

nti

al F

un

cti

on

For

desig

nate

d e

vents

within

the d

uty

cycle

, tr

ansport

reacto

r heat (r

educed p

ow

er

or

decay h

eat)

to a

n a

ltern

ate

heat sin

k, either

in the S

HT

S o

r th

epro

cess. [N

ote

: T

he

scope o

f th

is function is T

BD

.]

•A

ncilla

ry F

un

cti

on

s

Min

imiz

e e

nerg

y losses (

regenera

tive a

nd to the e

nvironm

ent)

Support

pers

onnel and in

vestm

ent pro

tection g

oals

Support

relia

bili

ty a

nd e

conom

ic g

oals

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Ou

tlin

eO

utl

ine

Seco

nd

ary

Wo

rkin

g F

luid

Seco

nd

ary

Wo

rkin

g F

luid

•In

tro

du

cti

on

•K

ey F

un

cti

on

s &

Req

uir

em

en

ts

•O

ve

rvie

w o

f C

oo

lan

t P

rop

ert

ies

•C

om

pari

so

n o

f O

pti

on

s

•S

um

mary

& R

eco

mm

en

dati

on

s

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Pro

pe

rtie

s o

f C

an

did

ate

SH

TS

Flu

ids

Pro

pe

rtie

s o

f C

an

did

ate

SH

TS

Flu

ids

NIS

T d

ata

not

pro

vid

ed a

bove

800C

0.0

35 (

@500C

)

0.0

44 (

@800C

)

0.0

66

(avg

. 500-8

00C

)

40.8

@7

MP

a

52.3

@9

MP

a

(avg

. 500-8

00C

)

1190 (

@500C

)

1270 (

@800C

)

47.6

/61.1

(@

500C

)

34.0

/43.5

(@

800C

)

NA

NA

CO

2

13 (

@500C

)

1.7

(@

1000C

)

23 (

@500C

)

2.2

(@

1000C

)

0.0

39 (

@500C

)

0.0

55 (

@1000

C)

, (P

a·s

) x 1

03

Well

chara

cte

rized;

Exp

ensiv

e;

Toxic

0.8

7

4270

2230

2010

(@700C

)

340

NaF

·BeF

2(5

7 –

43)

ZrF

4fa

mily

recom

mended

for

consid

era

tion

by O

RN

L.

Indiv

idual

salts

investigate

d

by O

NR

L.

Mix

ture

s n

ot

we

llchara

cte

rized.

Melt r

ange is

estim

ate

fo

r

various

mix

ture

s.

380 -

410

KF

-ZrF

4&

Rb

F-Z

rF4

Well

chara

cte

rized;

Used in M

SR

E;

Exp

ensiv

e,

Toxic

1

4555

2380

2036 (

@500C

)

1792 (

@1000C

)

1430

459

(LiF

) 2·B

eF

2

(FL

iBe)

Well

chara

cte

rized;

Refe

rence f

or

MS

BR

second

ary

; In

expensiv

e

Com

ments

4.5

0.3

68

(avg

. 500-1

000

C)

k, W

/(m

·K)

3649

17.9

@7

MP

a

23.1

@9

MP

aC

p, kJ/(

m3·K

)(a

vg.

500-1

000

C)

1889

5200

Cp, J/(

kg·K

)

2078 (

@500C

)

1785 (

@1000C

)

4.3

/5.5

(@

500

C)

2.6

/3.4

(@

1000C

)

, kg/m

3

(7M

Pa/9

MP

a)

Flu

robo

rate

s

recom

mended

for

consid

era

tion

by O

RN

L.

NaF

-NaB

F4

was r

efe

rence

secondary

coola

nt fo

r

MS

BR

(700C

), b

ut

V.P

too h

igh >

700C

.

Mix

ture

s m

ay

be s

uitable

.

NA

Tboil,

C

TB

D455

NA

Tm

elt, C

Alk

ali

Flu

rob

ora

tes

(Mix

Re

q’d

)

Na

F-K

F-L

iF(1

1.5

-42-4

6.5

)

(FL

iNaK

)

Heliu

mP

rop

ert

y

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Imp

licati

on

s o

f D

iffe

ren

ces in

Im

plicati

on

s o

f D

iffe

ren

ces in

Th

erm

op

hysic

al P

rop

ert

ies

Th

erm

op

hysic

al P

rop

ert

ies

•C

O2

has h

igh

er

vo

lum

etr

ic t

herm

al cap

acit

y (

Cp

) th

an

he

liu

m

Reduced p

um

pin

g p

ow

er

•H

eliu

m h

as h

igh

er

therm

al co

nd

ucti

vit

y (

k)

than

CO

2

Sm

alle

r hea

t exchangers

(IH

X a

nd P

CH

X)

•L

iqu

id s

alt

has a

mu

ch

hig

her

vo

lum

etr

ic t

herm

al cap

acit

y (

Cp

)th

an

heliu

m

Pip

ing d

iam

ete

r 1/5

th

Pum

pin

g p

ow

er

1/2

0th

or

low

er

•L

iqu

id s

alt

has m

uch

hig

her

heat

tran

sfe

r co

eff

icie

nts

Reduced L

MT

D r

equirem

ents

lo

wer

reacto

r outlet te

mpera

ture

fo

r giv

en p

rocess tem

pera

ture

or

hig

her

pro

cess tem

ps for

incre

ased e

ffic

iency

Sm

alle

r H

Xs

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Ou

tlin

eO

utl

ine

Seco

nd

ary

Wo

rkin

g F

luid

Seco

nd

ary

Wo

rkin

g F

luid

•In

tro

du

cti

on

•K

ey F

un

cti

on

s &

Req

uir

em

en

ts

•O

ve

rvie

w o

f C

oo

lan

t P

rop

ert

ies

•C

om

pari

so

n o

f O

pti

on

s

•S

um

mary

& R

eco

mm

en

dati

on

s

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Co

mp

ari

so

n o

f O

pti

on

sC

om

pari

so

n o

f O

pti

on

s

Ite

mH

eli

um

CO

2L

S

•D

esig

n C

om

pati

bilit

y+

-

--

•In

flu

en

ce o

n M

ajo

r C

om

po

nen

ts

He

at

Exch

an

ge

rs

+

-

+/-

Cir

cula

tors

/Pu

mp

s

-

+

++

Pip

ing a

nd Insula

tion

++

+

--

Va

lve

s a

nd

Se

als

-

--

+

•S

ys

tem

In

teg

rati

on

+

--

-

•S

yste

m O

pera

tio

n+

-

--

•A

va

ila

bil

ity

an

d R

eli

ab

ilit

y+

--

-

•S

afe

ty &

Lic

en

sin

g

+/-

-+

/-

•E

co

no

mic

Co

ns

ide

rati

on

s

+

/-+

/-+

•R

&D

+

-

--

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HH22

via

Hyb

rid

Su

lfu

r (H

yS

) C

ycle

via

Hyb

rid

Su

lfu

r (H

yS

) C

ycle

Refe

ren

ce C

om

merc

ial

Refe

ren

ce C

om

merc

ial

Pla

nt

Co

nfi

gu

rati

on

Pla

nt

Co

nfi

gu

rati

on

(So

urc

e:

Ref.

1)

PB

MR

IHX

Ox

yg

en

Re

co

ve

ryH

yd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

Deco

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

Ox

yg

en

Re

co

ve

ryH

yd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

Deco

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

Fu

lly I

nte

gra

ted

PG

S

SG

SG

HP

TL

PT

~ Co

nd

en

se

r

Pre

heate

r

Pro

cess P

lan

t B

att

ery

Lim

its

950C

290C

9M

Pa

350C

900C

9M

Pa

500M

Wt

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De

sig

n C

om

pa

tib

ilit

yD

es

ign

Co

mp

ati

bil

ity

•R

efe

ren

ce P

BM

R P

HP

co

nfi

gu

rati

on

fo

r H

yS

is c

om

pati

ble

wit

h h

eliu

m,

CO

2a

s S

HT

S f

luid

Co

mp

atib

ility

of

CO

2at hig

h tem

pera

ture

s a

n issue

•T

em

pera

ture

s in

SG

, re

turn

pip

ing

to

IH

X a

re in

co

mp

ati

ble

wit

h L

S w

ork

ing

flu

id d

ue t

o f

reezin

g p

oin

t o

f can

did

ate

salt

s

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Alt

ern

ate

NH

S C

ou

plin

g f

or

LS

SH

TS

Alt

ern

ate

NH

S C

ou

plin

g f

or

LS

SH

TS

950C

350C

900C

9M

Pa

674C

, 9M

Pa

186M

Wt

314M

Wt

To

PG

S

724C

500M

Wt

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De

sig

n C

om

pa

tib

ilit

yD

es

ign

Co

mp

ati

bil

ity

•S

ep

ara

tio

n o

f p

rocess h

eat,

SG

co

up

lin

g r

esu

lts in

incre

ased

seco

nd

ary

lo

op

retu

rn t

em

pera

ture

to

IH

X

Co

mp

atib

le w

ith

LS

fre

ezin

g p

oin

t

•F

or

SH

TS

wit

h g

as w

ork

ing

flu

id:

Incre

ased r

etu

rn tem

pera

ture

s p

oses feasib

ility

issues for

ga

s c

ircu

lato

r

Incre

ase

d S

HT

S r

etu

rn t

em

pe

ratu

re im

plie

s in

cre

ase

d

pum

pin

g p

ow

er,

but

offset

by d

ecre

ased v

olu

metr

ic f

low

rate

•H

PU

/PC

S i

nte

gra

tio

n m

ore

dif

ficu

lt w

ith

sep

ara

tio

n o

f

pro

ce

ss

he

at/

SG

co

up

lin

g

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48

He

at

Ex

ch

an

ge

rsH

ea

t E

xc

ha

ng

ers

He

lium

SH

TS

•H

igh

SH

TS

pre

ssu

re r

eq

uir

ed

fo

r eff

icie

nt

heat

tran

sp

ort

Consis

tent

with I

HX

pre

ssure

bala

ncin

g

Implie

s h

igh d

Pacro

ss P

CH

X

•C

om

para

ble

heat

tran

sp

ort

ch

ara

cte

risti

cs o

n

bo

th s

ide

s o

f IH

X

•M

eta

llic

HX

sfe

as

ible

, a

lbe

it m

arg

ina

l

CO

2S

HT

S

•H

igh

SH

TS

pre

ssu

re r

eq

uir

ed

fo

r eff

icie

nt

heat

tran

sp

ort

Consis

tent

with I

HX

pre

ssure

bala

ncin

g

Implie

s h

igh d

Pacro

ss P

CH

X

•S

ec

on

da

ry h

ea

t tr

an

sfe

r c

oe

ffic

ien

t w

ill

go

vern

H

X s

izin

g

For

giv

en d

uty

, H

X w

ill b

e larg

er,

more

expensiv

e

•M

eta

llic

HX

fe

as

ibil

ity q

ue

sti

on

ab

le

LS

SH

TS

•F

lex

ible

op

era

tin

g p

ress

ure

, esta

bli

sh

ed

by

co

ver

gas

Can s

tage p

ressure

diffe

rences b

etw

een

prim

ary

loop a

nd p

rocess

•P

ote

nti

al to

op

era

te w

ith

lo

wer

LM

TD

Reduce R

OT

for

giv

en p

rocess t

em

pera

ture

, or

Allo

w incre

ased p

rocess t

em

pera

ture

for

giv

en

RO

T

•M

ism

atc

h i

n h

eat

tran

sp

ort

ch

ara

cte

risti

cs

HT

co

eff

icie

nt,

vo

lum

etr

ic h

ea

t capacity m

uch

hig

her

on L

S s

ide

Prim

ary

heat tr

ansfe

r coeffic

ient w

ill g

overn

HX

siz

ing

Sim

plif

ies m

anifold

ing

in c

om

pact H

Xs

(see n

ext

slid

e)

Flo

w a

rea n

eeds to b

e m

uch s

malle

r on L

S s

ide

–F

ew

er,

sm

alle

r channels

–C

oncern

with

plu

gg

ing o

f sm

all

channels

in

co

mpact

HX

desig

ns

•L

ikely

to

req

uir

e c

era

mic

/CF

RH

Xs

Meta

l to

cera

mic

/CF

RC

inte

rfaces a

n issue

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Inle

t/O

utl

et

Man

ifo

lds in

In

let/

Ou

tlet

Man

ifo

lds in

He

He

-- He v

s. H

eH

e v

s. H

e-- L

SL

SH

Xs

HX

s

•A

dvan

tag

es i

n d

esig

n o

f in

let/

ou

tlet

man

ifo

lds w

ith

LS

HX

s

Gre

ate

r volu

metr

ic h

eat capacity r

esults in d

esig

ns w

ith s

malle

rpassages, lo

w p

ressure

lo

sses o

n L

S s

ide

Allo

ws s

malle

r H

Xs

and/o

r re

duced p

ressure

losses H

e-t

o-L

SH

e-t

o-H

e

Heli

um

-to

-LS

IH

XH

eli

um

-to

-Heli

um

IH

X

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He

at

Ex

ch

an

ge

rs (

Co

nt

He

at

Ex

ch

an

ge

rs (

Co

nt ’’

d)

d)

Heliu

m S

HT

S

•C

om

pati

ble

wit

h p

resen

t tu

be &

sh

ell

co

nvecti

ve r

efo

rmer

desig

ns

CO

2S

HT

S

•C

om

pati

ble

wit

h p

resen

t tu

be &

sh

ell

co

nvecti

ve r

efo

rmer

desig

ns

•F

or

giv

en

du

ty,

HX

wil

l b

e l

arg

er,

mo

re

ex

pe

ns

ive

LS

SH

TS

•N

ot

co

mp

ati

ble

wit

h t

ub

e &

sh

ell P

CH

X

desig

ns

Flo

w a

rea o

uts

ide o

f tu

bes is too larg

e for

LS

Would

need n

ew

PC

HX

desig

n

•F

or

giv

en

du

ty, H

X w

ill b

e s

maller,

mu

ch

less e

xp

en

siv

e

Advanta

ge f

or

heliu

m/d

isadvanta

ge f

or

CO

2/L

S w

ith

availa

ble

technolo

gy. F

utu

re a

dvanta

ge for

LS

with

com

pact cera

mic

/CR

FC

HX

s

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Cir

cu

lato

rs/P

um

ps

Cir

cu

lato

rs/P

um

ps

He

lium

SH

TS

•H

igh

est

pu

mp

ing

po

wer

•R

&D

issu

es w

ith

tem

pera

ture

s

ab

ov

e ~

35

0C

CO

2S

HT

S

•P

um

pin

g p

ow

er

low

er

tha

n

heliu

m, b

ut

>>

th

an

LS

•R

&D

issu

es w

ith

tem

pera

ture

s

ab

ov

e ~

35

0C

LS

SH

TS

•P

um

pin

g p

ow

er

<<

th

an

fo

r

gases

•P

um

ps d

em

on

str

ate

d in

earl

ier

LS

ap

plica

tio

ns

Advanta

ge f

or

CO

2vs.

he

lium

.

Larg

e a

dvanta

ge for

LS

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Pip

ing

an

d I

nsu

lati

on

Pip

ing

an

d I

nsu

lati

on

Heliu

m S

HT

S

•In

tern

al in

su

lati

on

typ

ically u

sed

to

re

du

ce p

ressu

re b

ou

nd

ary

tem

pera

ture

, re

du

ce e

nerg

y lo

sses

•P

ote

nti

al to

use c

oaxia

l d

ucts

fo

r h

ot/

co

ld leg

s

•P

ipin

g s

yste

ms d

em

on

str

ate

d, in

clu

din

g

in n

uc

lear

ap

plicati

on

s

•S

imil

ar

sys

tem

s u

se

d i

n P

BM

R D

PP

How

ever,

inte

rnal coolin

g a

pplie

d in

DP

P w

ould

be m

ore

difficult in P

HP

and

involv

e incre

ased e

nerg

y losses

CO

2S

HT

S

•A

s w

ith

heliu

m e

xcep

t th

at

pip

ing

an

d

valv

es m

ay b

e s

om

ew

hat

sm

aller

LS

SH

TS

•P

ipe s

ize ~

1/5

th

at

of

He p

ipe

•N

o k

no

wn

pra

cti

cal L

S w

ett

ed

in

su

lati

on

s

ys

tem

Implie

s p

ressure

boundary

must

opera

te a

t or

ne

ar

LS

tem

pera

ture

Elim

inate

s o

r m

akes m

ore

difficult

pote

ntial fo

r coaxia

l heat tr

ansport

•S

ug

gests

CF

RC

pre

ssu

re b

ou

nd

ary

Meta

llic m

ate

rials

may n

ot be a

dequate

at

900ºC

•E

xte

rnal in

su

lati

on

will b

e r

eq

uir

ed

to

re

du

ce e

nerg

y lo

sses

Esta

blis

hed technolo

gy a

majo

r advanta

ge for

heliu

m, re

duced

pip

e s

ize a

modest advanta

ge for

CO

2. L

ack o

f in

tern

al in

sula

tion

syste

m a

feasib

ility

issue for

LS

.

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Va

lve

s &

Se

als

Va

lve

s &

Se

als

Heliu

m S

HT

S

•V

ery

la

rge

va

lve

s r

eq

uir

ed

Siz

e a

nd p

ote

ntial fo

r le

akage p

roble

matical

for

SH

TS

isola

tion v

alv

es,

if r

equired

•L

eak-t

igh

t seals

dif

ficu

lt

Weld

ed s

eals

typic

al fo

r pre

ssure

boundary

Non-w

eld

ed s

eals

ha

ve b

een d

em

onstr

ate

d

for

inte

rnal com

ponents

CO

2S

HT

S

•L

arg

e v

alv

es r

eq

uir

ed

Siz

e a

nd p

ote

ntial fo

r le

akage p

roble

matical

for

SH

TS

isola

tion v

alv

es,

if r

equired

Pip

e d

iam

ete

rs m

ay b

e r

educed r

ela

tive t

o

heliu

m

•L

eak-t

igh

t seals

less d

iffi

cu

lt t

han

wit

h

heliu

m

LS

SH

TS

•S

mall v

alv

es r

eq

uir

ed

•M

ech

an

ical clo

su

re v

alv

es h

ave n

ot

yet

been

develo

ped

In e

arly a

pplic

ations,

LS

tended t

o c

lean

surf

ace t

o c

onditio

n t

hat

pro

mote

d s

elf-

weld

ing

Fre

eze v

alv

es w

ere

used in s

om

e e

arly

applic

ations;

effective,

but

slo

w

New

er

mate

rial altern

atives m

ake f

easib

ility

lik

ely

•N

o m

ech

an

ical seals

used

in

pri

or

desig

ns

New

er

mate

rial altern

atives m

ake f

easib

ility

lik

ely

Sig

nific

ant R

&D

issue for

heliu

m/C

O2

If S

HT

S

isola

tion v

alv

es r

equired. L

S w

ould

require

much s

malle

r valv

es/s

eals

.

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Sy

ste

m In

teg

rati

on

Sy

ste

m In

teg

rati

on

Heliu

m S

HT

S

•P

res

su

re d

iffe

ren

tia

l fr

om

pri

ma

ry t

o

pro

cess m

ust

larg

ely

be t

aken

acro

ss

PC

HX

•L

eakag

e b

iases:

More

fle

xib

le for

IHX

PC

HX

bia

sed tow

ard

pro

cess

CO

2S

HT

S

•P

res

su

re d

iffe

ren

tia

l fr

om

pri

ma

ry t

o

pro

cess m

ust

larg

ely

be t

aken

acro

ss

PC

HX

•L

eakag

e b

iases

:

IHX

must be b

iased tow

ard

SH

TS

PC

HX

bia

sed tow

ard

pro

cess

LS

SH

TS

•F

lexib

ilit

y t

o s

tag

e p

rim

ary

to

pro

cess

pre

ssu

re d

iffe

ren

tial

•L

eakag

eb

iases

:

IHX

leakage m

ust be b

iased tow

ard

LS

sid

e o

f IH

X

PC

HX

le

aka

ge

bia

s:

–If t

ow

ard

LS

sid

e,

need t

o e

valu

ate

consequences o

f pro

cess g

as ingre

ss

–If

to

wa

rd L

S s

ide

, im

plie

s h

igh d

Pa

cro

ss

IHX

–If t

ow

ard

pro

cess s

ide,

must

assess

consequences o

f salt c

onta

min

ation

Leakage b

ias a

nd c

onsequences a

dis

advanta

ge f

or

CO

2; fe

asib

ility

issue for

LS

.

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Sy

ste

m O

pe

rati

on

Sy

ste

m O

pe

rati

on

Heliu

m S

HT

S

•S

ign

ific

an

t o

pera

tio

nal exp

eri

en

ce w

ith

heliu

m h

eat

tran

sp

ort

; n

o m

ajo

r is

su

es

CO

2S

HT

S

•S

ign

ific

an

t o

pera

tio

nal exp

eri

en

ce w

ith

CO

2h

eat

tran

sp

ort

at

low

er

tem

pera

ture

s;

no

majo

r is

su

es

LS

SH

TS

•S

tart

up

/Sh

utd

ow

n

Sa

lt m

ust

be h

ea

ted

to liq

uid

sta

te a

nd

in

troduced

to

SH

TS

as p

art

of

sta

rtu

p

LS

must

be d

rain

ed f

or

cold

shutd

ow

n

Tem

pera

ture

must be m

ain

tain

ed a

bove

min

imum

level fo

r hot sta

ndby

Altern

ate

heat

sourc

e r

equired f

or

above

•S

tead

y S

tate

/Tra

nsie

nts

No u

nusual is

sues a

nticip

ate

d w

ith s

teady

sta

te o

pera

tion

Tra

nsie

nts

resultin

g in s

hutd

ow

n a

ddre

ssed

above

Fre

ezin

g o

f L

S im

plies s

ign

ific

an

t

op

era

tio

nal is

su

es w

ith

sta

rtu

p, sh

utd

ow

n

an

d r

esp

on

se t

o c

ert

ain

tra

nsie

nts

.

Op

era

tio

nal exp

eri

en

ce w

ith

heliu

m a

t h

igh

tem

pera

ture

s a

n a

dvan

tag

e.

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Av

ail

ab

ilit

y/R

eli

ab

ilit

yA

va

ila

bil

ity

/Re

lia

bil

ity

Heliu

m S

HT

S

•C

on

tin

ued

op

era

tio

n w

ith

sm

all H

X

leaks m

ay b

e p

ossib

le

•D

iffi

cu

lty in

lo

cati

ng

/rep

air

ing

leaks a

pro

ble

m w

ith

co

mp

act

HX

s

CO

2S

HT

S

•M

ust

be s

hu

t d

ow

n w

hen

an

y leak is

dete

cte

d

•D

iffi

cu

lty in

lo

cati

ng

/rep

air

ing

leaks a

pro

ble

m w

ith

co

mp

act

HX

s

LS

SH

TS

•M

ust

be s

hu

t d

ow

n w

hen

an

y leak is

dete

cte

d

•D

iffi

cu

lty in

lo

cati

ng

/rep

air

ing

leaks a

pro

ble

m w

ith

co

mp

act

HX

s

Consequences o

f le

aks a

dis

advanta

ge

of C

O2, m

ajo

r dis

advanta

ge o

f LS

.

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Sa

fety

/Lic

en

sin

gS

afe

ty/L

ice

ns

ing

He

lium

SH

TS

•R

eq

uir

es p

rocess t

o b

e c

lose t

o

reacto

r

CO

2S

HT

S

•R

eq

uir

es p

rocess t

o b

e c

lose t

o

reacto

r

•C

on

seq

uen

ces o

f C

O2

ing

ress in

to

pri

mary

lo

op

may h

ave t

o b

e

ad

dre

ssed

LS

SH

TS

•F

lex

ibil

ity

fo

r m

ov

ing

pro

ce

ss

fart

he

r fr

om

re

ac

tor

•C

on

seq

uen

ces o

f salt

in

gre

ss in

to

pri

mary

lo

op

may h

ave t

o b

e

ad

dre

ssed

Pote

ntial fo

r S

HT

S leaks into

prim

ary

syste

m a

dis

advanta

ge f

or

CO

2, p

ote

ntia

lly a

ma

jor

issu

e fo

r L

S. L

S

would

allo

w g

reate

r dis

tance b

etw

een r

eacto

r and p

rocess.

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Eco

no

mic

sE

co

no

mic

s

Heliu

m S

HT

S

•B

ase f

or

co

mp

ari

so

n

CO

2S

HT

S

•T

rad

eo

ff o

f la

rger

heat

exch

an

gers

(IH

X,

PC

HX

) vs. re

du

ced

pu

mp

ing

co

sts

Furt

her

evalu

ation r

equired to

dete

rmin

e n

et im

pact

LS

SH

TS

•C

ap

ital co

st

likely

to

be lo

wer

IHX

, P

HC

E,

ma

in S

HT

S c

om

po

ne

nts

w

ill b

e s

malle

r, less e

xpensiv

e

How

ever,

an o

ffset w

ill b

e a

dditio

nal

au

xili

ary

syste

ms r

eq

uire

d fo

r m

eltin

g,

LS

tem

pera

ture

contr

ol

Capital cost advanta

ge w

ill incre

ase

with d

ista

nce b

etw

een IH

X a

n P

CH

X

•O

pera

tin

g c

osts

ma

y b

e h

igh

er

or

low

er

Low

er

pum

pin

g c

osts

(dis

tance a

key

para

mete

r)

Hig

her

main

tenance c

osts

Pote

ntially

sig

nific

ant capital cost advanta

ge for

LS

, b

ut

op

era

tin

g c

ost

tra

de

off

s u

nce

rta

in.

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R&

D R

eq

uir

em

en

tsR

&D

Re

qu

ire

me

nts

Heliu

m S

HT

S

•IH

X

•IH

X c

ore

to

meta

l tr

an

sit

ion

s

Applie

s t

o c

era

mic

/CF

RC

IH

X

•Is

ola

tio

n v

alv

es

•P

CH

X

CO

2S

HT

S

•IH

X

Mate

rial co

mp

ati

bilit

y a

t is

su

e f

or

meta

llic

HX

s

•IH

X c

ore

to

meta

l tr

an

sit

ion

s

Applie

s t

o c

era

mic

/CF

RC

IH

X

•Is

ola

tio

n v

alv

es

•P

CH

X

LS

SH

TS

•IH

X

Will alm

ost

cert

ain

ly r

eq

uir

e

ce

ram

ic/C

FR

C I

HX

•IH

X c

ore

to

meta

l tr

an

sit

ion

s

Applie

s t

o c

era

mic

/CF

RC

IH

X

•Is

ola

tio

n v

alv

es

•S

HT

S p

ipin

g a

nd

in

su

lati

on

•P

CH

X

•P

um

p a

nd

seals

R&

D s

om

ew

ha

t g

rea

ter

for

CO

2if m

eta

llic H

Xs

are

feasib

le.

LS

requires m

ajo

r R

&D

initia

tive.

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60

Ou

tlin

eO

utl

ine

Seco

nd

ary

Wo

rkin

g F

luid

Seco

nd

ary

Wo

rkin

g F

luid

•In

tro

du

cti

on

•K

ey F

un

cti

on

s &

Req

uir

em

en

ts

•O

ve

rvie

w o

f C

oo

lan

t P

rop

ert

ies

•C

om

pari

so

n o

f O

pti

on

s

Influence o

n M

ajo

r C

om

ponents

Syste

m I

nte

gra

tion a

nd O

pera

tion

Availa

bili

ty a

nd R

elia

bili

ty

Safe

ty &

Lic

ensin

g

Econom

ic C

onsid

era

tions

R&

D

•S

um

mary

& R

eco

mm

en

dati

on

s

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Co

nc

lus

ion

s a

nd

Re

co

mm

en

da

tio

ns

Co

nc

lus

ion

s a

nd

Re

co

mm

en

da

tio

ns

•W

ith

rela

tively

lo

w r

etu

rn t

em

pera

ture

of

co

mm

erc

ial P

BM

R P

HP

fo

r H

yS

, in

ce

nti

ve

s f

or

CO

2vs. h

eliu

m a

re lik

ely

to

be m

od

est,

if

at

all

Mate

rials

com

patibili

ty issues m

ay b

e s

ignific

ant

•D

esig

n a

nd

op

era

tio

nal is

su

es m

ake L

S p

rob

lem

ati

cal at

cu

rren

t sta

ge o

f d

evelo

pm

en

t

Incentives a

re incre

ased w

ith g

reate

r dis

tance b

etw

een h

eat

sourc

e a

nd p

rocess p

lant

•N

GN

P p

reco

ncep

tual d

esig

n s

ho

uld

be b

ased

on

heli

um

SH

TS

w

ith

PC

HX

lo

cate

d a

t a r

ela

tively

sh

ort

dis

tan

ce (

e.g

., 1

00m

) fr

om

th

e r

eacto

r th

at

is r

ep

resen

tati

ve o

f co

mm

erc

ial ap

plicati

on

s

•C

on

tin

ue d

evelo

pm

en

t o

f L

S H

TS

–lo

ng

er

term

en

han

cin

g

tech

no

log

y

Tert

iary

loop

on N

GN

P c

ould

be p

ote

ntial ba

sis

for

futu

re

dem

onstr

atio

n

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APPENDIX 20.3.1: SPECIAL STUDY 20.3.1 SLIDES

PART 4 – HEAT TRANSPORT SYSTEM OPTIONS

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1

SP

EC

IAL

ST

UD

IES

:S

PE

CIA

L S

TU

DIE

S:

20

.32

0.3

--H

EA

T T

RA

NS

PO

RT

SY

ST

EM

H

EA

T T

RA

NS

PO

RT

SY

ST

EM

20

.42

0.4

--P

OW

ER

CO

NV

ER

SIO

N S

YS

TE

M

PO

WE

R C

ON

VE

RS

ION

SY

ST

EM

Pa

rt 4

P

art

4 ––

He

at

Tra

ns

po

rt S

ys

tem

Op

tio

ns

He

at

Tra

ns

po

rt S

ys

tem

Op

tio

ns

De

ce

mb

er

6,

20

06

De

ce

mb

er

6,

20

06

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2

Ou

tlin

eO

utl

ine

•O

bje

cti

ve a

nd

Sco

pe

•S

tud

y In

pu

tsC

om

merc

ial applic

ations a

nd p

erf

orm

ance r

equirem

ents

Key N

GN

P H

TS

dem

onstr

ation o

bje

ctives

Key H

TS

functional re

quirem

ents

Oth

er

input re

quirem

ents

and d

ata

•S

cre

en

ing

Cri

teri

a

•P

ow

er

Co

nvers

ion

Syste

m O

pti

on

s (

20.4

)

•H

2P

rod

ucti

on

Un

it S

ize (

20.7

)

•IH

X/H

igh

-Tem

pera

ture

Mate

rials

•S

eco

nd

ary

Wo

rkin

g F

luid

•H

TS

Co

nfi

gu

rati

on

Op

tio

ns

•R

eco

mm

en

ded

HT

S C

on

fig

ura

tio

n

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3

Pro

ce

ss

He

at/

PC

S

Pro

ce

ss

He

at/

PC

S

Co

nfi

gu

rati

on

Hie

rarc

hy

Co

nfi

gu

rati

on

Hie

rarc

hy

PB

MR

Ind

irect

PC

SD

ire

ct

PC

S

Bra

yto

n C

yc

le

Seri

es o

r P

ara

llel

IHX

Pro

cess I

nte

gra

ted

or

No

PC

S

Ste

am

Cyc

le

Seco

nd

ary

PC

S

Ste

am

Cyc

le

Gas T

urb

ine

Co

mb

ine

d C

yc

le

Seri

es o

r P

ara

llel

IHX

Bra

yto

n C

yc

le

Seri

es o

r P

ara

llel

IHX

Gas T

urb

ine

Co

mb

ine

d C

yc

le

Seri

es o

r P

ara

llel

IHX

Pri

mary

/Seco

nd

ary

SG

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20.3

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art

4 -

12/6

/2006

4

Scre

en

ing

Cri

teri

aS

cre

en

ing

Cri

teri

a

Att

rib

ute

Imp

ort

an

ce

•R

ead

iness

Ab

ilit

y t

o m

ee

t N

GN

P t

ime

lin

e (

sta

rtu

p:

20

16

-201

8)

Hig

h

NG

NP

R&

D R

equirem

ents

/Cost/R

isk

Med

Vendor/

Supplie

r/R

egula

tory

Infr

astr

uctu

re D

evelo

pm

ent

Med

•S

up

po

rt o

f C

om

merc

ial

Ap

pli

ca

tio

ns

Ad

eq

uate

ly d

em

on

str

ate

s c

om

merc

ial

pro

cess h

eat

Hig

ha

pp

lic

ati

on

s

NH

S c

om

mo

na

lity

wit

h c

om

merc

ial

pro

du

cts

Hig

h

Can

serv

e a

s p

rocess h

eat

pro

toty

pe f

or

desig

n c

ert

ific

ati

on

Hig

h

Fle

xib

ility

for

dem

onstr

ating a

dvanced a

pplic

ations

Med

Fle

xib

ility

for

ultim

ate

NG

NP

convers

ion t

o f

ull-

scale

H2 p

roduction

Med

•P

erf

orm

an

ce

Ab

ilit

y t

o m

ee

t o

pe

rati

on

al

pe

rfo

rma

nc

e g

oa

lsH

igh

Overa

ll P

lant

Effic

iency

Low

Opera

bili

tyM

ed

Availa

bili

tyLow

•C

ost

NG

NP

Ca

pit

al

Co

st

Hig

h

NG

NP

Opera

ting C

ost

Low

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20.3

/20.4

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art

4 -

12/6

/2006

5

Pro

ce

ss

He

at/

PC

SP

roc

es

s H

ea

t/P

CS

Co

nfi

gu

rati

on

Hie

rarc

hy

Co

nfi

gu

rati

on

Hie

rarc

hy

PB

MR

Ind

irect

PC

SD

ire

ct

PC

S

Bra

yto

n C

yc

le

Seri

es o

r P

ara

llel

IHX

Pro

cess I

nte

gra

ted

or

No

PC

S

Ste

am

Cyc

le

Seco

nd

ary

PC

S

Ste

am

Cyc

le

Gas T

urb

ine

Co

mb

ine

d C

yc

le

Seri

es o

r P

ara

llel

IHX

Bra

yto

n C

yc

le

Seri

es o

r P

ara

llel

IHX

Gas T

urb

ine

Co

mb

ine

d C

yc

le

Seri

es o

r P

ara

llel

IHX

Pri

mary

/Seco

nd

ary

SG

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20.3

/20.4

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art

4 -

12/6

/2006

6

Op

tio

n 1

:O

pti

on

1:

Pri

mary

Bra

yto

n C

ycle

/GT

CC

, S

eri

es IH

XP

rim

ary

Bra

yto

n C

ycle

/GT

CC

, S

eri

es IH

X

PB

MR

Ox

yg

en

Re

co

ve

ryH

yd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

Deco

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

Ox

yg

en

Re

co

ve

ryH

yd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

Deco

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

RH

X

Pre

co

ole

r

Inte

rco

ole

r

PT

~G

BL

PC

HP

C

RH

XR

HX

Pre

co

ole

r

Inte

rco

ole

r

PT

~G

BL

PC

HP

C

Inte

rco

ole

r

PT

~G

BL

PC

HP

CP

T~

GB

LP

CH

PC

OR

*

* T

o b

e s

ele

cte

d in

PC

S S

pecia

l

Stu

dy 2

0.4

, if

re

qu

ired

PT

~G

BC

OM

P

SG

HP

TIP

TL

PT

~

RH

X

Co

nd

en

se

r

Pre

co

ole

r-1

Pre

co

ole

r-2

Bleed Flow

Pre

hea

t F

low

PT

~G

BC

OM

PP

T~

GB

CO

MP

SG

SG

HP

TIP

TL

PT

~

RH

XR

HX

Co

nd

en

se

r

Pre

co

ole

r-1

Pre

co

ole

r-2

Bleed Flow

Pre

hea

t F

low

Meta

lo

rS

iCIH

X

No

te:

HyS

sh

ow

n a

s r

ep

resen

tati

ve

H2 p

rod

uc

tio

n p

rocess, c

ou

ld

als

o b

e S

-I

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20.3

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art

4 -

12/6

/2006

7

Op

tio

n 1

:O

pti

on

1:

Pri

mary

Bra

yto

n C

ycle

/GT

CC

, S

eri

es IH

XP

rim

ary

Bra

yto

n C

ycle

/GT

CC

, S

eri

es IH

X

Key F

eatu

res

•S

ma

ll (

~5

0M

Wt)

to

pp

ing

IH

X

Desig

ned f

or

easy r

epla

cem

ent, b

ut

more

difficult t

han p

ara

llel (O

ption 2

)

Option t

o u

se liq

uid

salt S

HT

S w

ork

ing f

luid

Option t

o o

pera

te w

ithout

IHX

•D

irect

Bra

yto

n o

r G

TC

C b

ott

om

ing

cycle

Option t

o u

se 9

00ºC

DP

P P

CS

Read

iness

•B

rayto

n c

ycle

/GT

CC

based

on

DP

PN

o R

&D

at

900ºC

or

modest

R&

D t

o 9

50ºC

•O

pti

on

to

op

era

te P

CS

wit

ho

ut

IHX

in

sta

lle

d

•S

ign

ific

an

t p

rim

ary

/ s

ec

on

da

ry f

low

mis

ma

tch

Prim

ary

sid

e o

f IH

X m

ust

be d

esig

ned f

or

full

flow

(pote

ntial is

sues w

ith b

ypass/h

ot

str

eaks)

SH

TS

circula

tor

tem

pera

ture

an issue

Su

pp

ort

of

Co

mm

erc

ial

Ap

pli

ca

tio

ns

•L

ow

NH

S c

om

mo

nality

wit

h c

om

merc

ial P

HP

May b

e inadequate

as p

roto

type for

desig

n

cert

ific

ation o

f P

HP

com

merc

ial pla

nts

•G

TC

C v

ari

an

t s

up

po

rts

de

plo

ym

en

t o

f A

EP

Perf

orm

an

ce

•S

ing

le P

HT

S f

low

pa

th a

vo

ids

op

era

tio

na

l is

su

es w

ith

rem

ixin

g o

f sep

ara

te f

low

s

(Op

tio

n 2

)

•P

CS

pro

vid

e a

ltern

ate

heat

sin

k (

co

ole

rs)

for

off

-no

rma

l e

ve

nts

•P

ressu

re t

ran

sie

nts

asso

cia

ted

wit

h B

rayto

n

cycle

tra

nsie

nts

mu

st

be c

on

sid

ere

d

Co

st

•C

ap

ital

Alo

ng w

ith O

ptions 2

and 5

, am

ong low

est

capital cost

options

Sm

all

IHX

im

plie

s m

odest

repla

cem

ent

capital

cost

•O

pe

rati

ng

Pote

ntial fo

r good e

ffic

iency, hig

h a

vaila

bili

ty

to m

axim

ize c

ost

offsets

via

ele

ctr

ic s

ale

s

PC

S m

ain

tenance h

igher

with d

irect

cycle

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20.3

/20.4

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art

4 -

12/6

/2006

8

Op

tio

n 2

:O

pti

on

2:

Pri

mary

Bra

yto

n C

ycle

/GT

CC

, P

ara

llel IH

XP

rim

ary

Bra

yto

n C

ycle

/GT

CC

, P

ara

llel IH

X

PB

MR

Tri

m

HX

Mix

er

Ox

yg

en

Re

co

ve

ryH

yd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

Deco

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

Ox

yg

en

Re

co

ve

ryH

yd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

Deco

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

RH

X

Pre

co

ole

r

Inte

rco

ole

r

PT

~G

BL

PC

HP

C

RH

XR

HX

Pre

co

ole

r

Inte

rco

ole

r

PT

~G

BL

PC

HP

C

Inte

rco

ole

r

PT

~G

BL

PC

HP

CP

T~

GB

LP

CH

PC

OR*

* T

o b

e s

ele

cte

d in

PC

S S

pecia

l

Stu

dy 2

0.4

, if

re

qu

ired

Meta

lo

rS

iCIH

X

PT

~G

BC

OM

P

SG

HP

TIP

TL

PT

~

RH

X

Co

nd

en

se

r

Pre

co

ole

r-1

Pre

co

ole

r-2

Bleed Flow

Pre

he

at

Flo

w

PT

~G

BC

OM

PP

T~

GB

CO

MP

SG

SG

HP

TIP

TL

PT

~

RH

XR

HX

Co

nd

en

se

r

Pre

co

ole

r-1

Pre

co

ole

r-2

Bleed Flow

Pre

he

at

Flo

w

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20.3

/20.4

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art

4 -

12/6

/2006

9

Op

tio

n 2

:O

pti

on

2:

Pri

mary

Bra

yto

n C

ycle

/GT

CC

, P

ara

llel IH

XP

rim

ary

Bra

yto

n C

ycle

/GT

CC

, P

ara

llel IH

X

Key F

eatu

res

•S

ma

ll (

~5

0M

Wt)

pa

rall

el

IHX

Desig

ned f

or

easy r

epla

cem

ent

(easie

st)

Option t

o o

pera

te w

ithout

IHX

•D

irect

Bra

yto

n c

ycle

or

GT

CC

Requires 9

50ºC

desig

n b

asis

Read

iness

•B

rayto

n c

ycle

/GT

CC

extr

ap

ola

ted

fro

m D

PP

Modest

R&

D a

t 950ºC

•O

pti

on

to

op

era

te P

CS

wit

ho

ut

IHX

in

sta

lle

dF

acili

tate

d b

y s

malle

r, p

ara

llel P

HT

S p

ipin

g

•R

eq

uir

es

pro

vis

ion

s t

o c

on

tro

l p

ara

lle

l fl

ow

s,

rem

ix p

ara

llel

str

eam

s t

hat

are

po

ten

tiall

y a

t d

iffe

ren

t te

mp

era

ture

s

Su

pp

ort

of

Co

mm

erc

ial

Ap

pli

ca

tio

ns

•L

ow

NH

S c

om

mo

nality

wit

h c

om

merc

ial P

HP

May b

e inadequate

as p

roto

type for

desig

n

cert

ific

ation o

f P

HP

com

merc

ial pla

nts

•G

TC

C v

ari

an

t s

up

po

rts

de

plo

ym

en

t o

f A

EP

Perf

orm

an

ce

•P

ara

lle

l P

HT

S f

low

path

s i

mp

ly o

pe

rati

on

al

issu

es w

ith

rem

ixin

g

•P

CS

pro

vid

es a

ltern

ate

heat

sin

k (

co

ole

rs)

for

off

-no

rma

l e

ve

nts

•P

ressu

re t

ran

sie

nts

asso

cia

ted

wit

h B

rayto

n

cycle

tra

nsie

nts

mu

st

be c

on

sid

ere

d

Co

st

•C

ap

ital

Alo

ng w

ith O

ptions 1

and 5

, am

ong low

est

capital cost

options

Sm

all

IHX

im

plie

s m

odest

repla

cem

ent

capital

cost

•O

pe

rati

ng

Pote

ntial fo

r good e

ffic

iency, good a

vaila

bili

ty

to m

axim

ize c

ost

offsets

via

ele

ctr

ic s

ale

s

PC

S m

ain

tenance h

igher

with d

irect

cycle

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20.3

/20.4

: P

art

4 -

12/6

/2006

10

Pro

ce

ss

He

at/

PC

SP

roc

es

s H

ea

t/P

CS

Co

nfi

gu

rati

on

Hie

rarc

hy

Co

nfi

gu

rati

on

Hie

rarc

hy

PB

MR

Ind

irect

PC

SD

ire

ct

PC

S

Bra

yto

n C

yc

le

Seri

es o

r P

ara

llel

IHX

Pro

cess I

nte

gra

ted

or

No

PC

S

Ste

am

Cyc

le

Seco

nd

ary

PC

S

Ste

am

Cyc

le

Gas T

urb

ine

Co

mb

ine

d C

yc

le

Seri

es o

r P

ara

llel

IHX

Bra

yto

n C

yc

le

Seri

es o

r P

ara

llel

IHX

Gas T

urb

ine

Co

mb

ine

d C

yc

le

Seri

es o

r P

ara

llel

IHX

Pri

mary

/Seco

nd

ary

SG

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20.3

/20.4

: P

art

4 -

12/6

/2006

11

Op

tio

n 3

:O

pti

on

3:

Se

co

nd

ary

Bra

yto

n C

yc

le/G

TC

C,

Se

rie

s P

CH

XS

ec

on

da

ry B

ray

ton

Cy

cle

/GT

CC

, S

eri

es

PC

HX

PB

MR

Ox

yg

en

Re

co

ve

ryH

yd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

Deco

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

Ox

yg

en

Re

co

ve

ryH

yd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

Deco

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

RH

X

Pre

co

ole

r

Inte

rco

ole

r

PT

~G

BL

PC

HP

C

RH

XR

HX

Pre

co

ole

r

Inte

rco

ole

r

PT

~G

BL

PC

HP

C

Inte

rco

ole

r

PT

~G

BL

PC

HP

CP

T~

GB

LP

CH

PC

OR

*

* T

o b

e s

ele

cte

d in

PC

S S

pecia

l

Stu

dy 2

0.4

, if

re

qu

ired

Meta

l

IHX

Meta

lo

rS

iCIH

X

PT

~G

BC

OM

P

SG

HP

TIP

TL

PT

~

RH

X

Co

nd

en

ser

Pre

co

ole

r-1

Pre

co

ole

r-2

Bleed Flow

Pre

he

at

Flo

w

PT

~G

BC

OM

PP

T~

GB

CO

MP

SG

SG

HP

TIP

TL

PT

~

RH

XR

HX

Co

nd

en

ser

Pre

co

ole

r-1

Pre

co

ole

r-2

Bleed Flow

Pre

he

at

Flo

w

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20.3

/20.4

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art

4 -

12/6

/2006

12

Op

tio

n 3

:O

pti

on

3:

Se

co

nd

ary

Bra

yto

n C

yc

le/G

TC

C,

Se

rie

s P

CH

XS

ec

on

da

ry B

ray

ton

Cy

cle

/GT

CC

, S

eri

es

PC

HX

Key F

eatu

res

•F

ull-s

ize I

HX

tra

nsfe

rs a

ll r

eacto

r h

eat

to S

HT

S

•S

ma

ll (

~50M

Wt)

PC

HX

as t

op

pin

g c

ycle

•B

rayto

n c

yc

le o

r G

TC

C b

ott

om

ing

cyc

le850ºC

PC

S d

esig

n b

asis

•P

CH

X/P

CS

lik

ely

need

to

be c

o-l

ocate

d

Read

iness

•B

rayto

n c

ycle

/GT

CC

extr

ap

ola

ted

fro

m D

PP

No R

&D

to 9

00ºC

•O

pti

on

to

op

era

te P

CS

wit

ho

ut

PC

HX

in

sta

lle

d

•L

arg

e I

HX

po

ses g

reate

st

ch

allen

ge t

o

read

iness

Su

pp

ort

of

Co

mm

erc

ial

Ap

pli

ca

tio

ns

•H

igh

NH

S c

om

mo

nality

wit

h c

om

merc

ial

PH

P

If s

uccessfu

l, r

esolv

es I

HX

issue f

or

com

merc

ial pla

nts

Adequate

pro

toty

pe f

or

desig

n c

ert

ific

ation o

f P

HP

com

merc

ial pla

nts

•G

TC

C v

ari

an

t s

up

po

rts

de

plo

ym

en

t o

f A

EP

Perf

orm

an

ce

•P

CS

pro

vid

es

alt

ern

ate

he

at

sin

k (

co

ole

rs)

for

off

-no

rma

l e

ve

nts

Requires o

pera

tional P

HT

S

•P

ressu

re t

ran

sie

nts

asso

cia

ted

wit

h B

rayto

n

cycle

tra

nsie

nts

mu

st

be c

on

sid

ere

d

•S

ign

ific

an

t a

va

ila

bil

ity r

isk

as

so

cia

ted

wit

h

po

ten

tia

l fo

r IH

X l

ea

ks

Co

st

•C

ap

ital

Hig

h c

apital cost

rela

tive t

o d

irect

PC

S o

ptions

Larg

e I

HX

im

plie

s p

ote

ntial fo

r hig

h

repla

cem

ent

capital costs

–M

ay b

e m

itig

ate

d b

y s

ele

ction o

f cera

mic

m

ate

rial and/o

r split

section d

esig

n

•O

pe

rati

ng

Low

er

effic

iency, availa

bili

ty r

isk m

ay r

educe

cost

offsets

via

ele

ctr

ic s

ale

s

Main

tenance c

osts

involv

e t

radeoff o

f IH

X/c

ircula

tor

vs.

PC

S

Page 288: NGNP and Hydrogen Production Preconceptual Design Report Documents... · NGNP and Hydrogen Production Preconceptual Design Report NGNP-20-RPT-003 Special Study 20.3 – High Temperature

20.3

/20.4

: P

art

4 -

12/6

/2006

13

Op

tio

n 4

:O

pti

on

4:

Se

co

nd

ary

Bra

yto

n C

yc

le/G

TC

C,

Pa

rall

el P

CH

XS

ec

on

da

ry B

ray

ton

Cy

cle

/GT

CC

, P

ara

lle

l P

CH

X

PB

MR

Ox

yg

en

Re

co

ve

ryH

yd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

Deco

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

Ox

yg

en

Re

co

ve

ryH

yd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

Deco

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

RH

X

Pre

co

ole

r

Inte

rco

ole

r

PT

~G

BL

PC

HP

C

RH

XR

HX

Pre

co

ole

r

Inte

rco

ole

r

PT

~G

BL

PC

HP

C

Inte

rco

ole

r

PT

~G

BL

PC

HP

CP

T~

GB

LP

CH

PC

OR

*

* T

o b

e s

ele

cte

d in

PC

S S

pecia

l

Stu

dy 2

0.4

, if

re

qu

ired

Meta

l

IHX

Meta

lo

rS

iCIH

X

PT

~G

BC

OM

P

SG

HP

TIP

TL

PT

~

RH

X

Co

nd

en

ser

Pre

co

ole

r-1

Pre

co

ole

r-2

Bleed Flow

Pre

hea

t F

low

PT

~G

BC

OM

PP

T~

GB

CO

MP

SG

SG

HP

TIP

TL

PT

~

RH

XR

HX

Co

nd

en

ser

Pre

co

ole

r-1

Pre

co

ole

r-2

Bleed Flow

Pre

hea

t F

low

Page 289: NGNP and Hydrogen Production Preconceptual Design Report Documents... · NGNP and Hydrogen Production Preconceptual Design Report NGNP-20-RPT-003 Special Study 20.3 – High Temperature

20.3

/20.4

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art

4 -

12/6

/2006

14

Op

tio

n 4

:O

pti

on

4:

Se

co

nd

ary

Bra

yto

n C

yc

le/G

TC

C,

Pa

rall

el P

CH

XS

ec

on

da

ry B

ray

ton

Cy

cle

/GT

CC

, P

ara

lle

l P

CH

X

Key F

eatu

res

•F

ull-s

ize I

HX

tra

nsfe

rs a

ll r

eacto

r h

eat

to S

HT

S

•S

ma

ll (

~50M

Wt)

para

llel

PC

HX

•B

rayto

n o

r G

TC

C c

yc

leR

equires 9

00ºC

desig

n b

asis

•P

CH

X/P

CS

lik

ely

to

be c

o-l

ocate

d

Read

iness

•B

rayto

n c

ycle

/GT

CC

extr

ap

ola

ted

fro

m D

PP

No R

&D

at 900ºC

•O

pti

on

to

op

era

te P

CS

wit

ho

ut

PC

HX

in

sta

lle

d

•L

arg

e I

HX

po

ses g

reate

st

ch

allen

ge t

o

read

iness

•R

eq

uir

es

pro

vis

ion

s t

o c

on

tro

l p

ara

lle

l fl

ow

s,

rem

ix p

ara

llel

str

eam

s t

hat

are

po

ten

tiall

y a

t d

iffe

ren

t te

mp

era

ture

s

Su

pp

ort

of

Co

mm

erc

ial

Ap

pli

ca

tio

ns

•H

igh

NH

S c

om

mo

nality

wit

h c

om

merc

ial

PH

P

If s

uccessfu

l, r

esolv

es I

HX

issue f

or

com

merc

ial pla

nts

Adequate

pro

toty

pe f

or

desig

n c

ert

ific

ation o

fP

HP

com

merc

ial pla

nts

•G

TC

C v

ari

an

t s

up

po

rts

de

plo

ym

en

t o

f A

EP

Perf

orm

an

ce

•P

CS

pro

vid

es a

ltern

ate

heat

sin

k (

co

ole

rs)

for

off

-no

rma

l e

ve

nts

Requires o

pera

tional P

HT

S

•P

ara

llel

PH

TS

flo

w p

ath

s i

mp

ly o

pera

tio

nal

issu

es w

ith

rem

ixin

g

•S

ign

ific

an

t a

va

ila

bil

ity r

isk

as

so

cia

ted

wit

h

po

ten

tia

l fo

r IH

X l

ea

ks

•P

ressu

re t

ran

sie

nts

asso

cia

ted

wit

h B

rayto

n

cycle

tra

nsie

nts

mu

st

be c

on

sid

ere

d

Co

st

•C

ap

ital

Hig

her

capital cost

rela

tive t

o d

irect

PC

S

options

Larg

e I

HX

im

plie

s p

ote

ntial fo

r hig

h

repla

cem

ent

capital costs

–M

ay b

e m

itig

ate

d b

y s

ele

ction o

f cera

mic

m

ate

rial and/o

r split

section d

esig

n

•O

pe

rati

ng

Low

er

effic

iency, availa

bili

ty r

isk m

ay r

educe

cost

offsets

via

ele

ctr

ic s

ale

s

Main

tenance

costs

involv

e t

radeoff o

f IH

X/c

ircula

tor

vs.

PC

S

Page 290: NGNP and Hydrogen Production Preconceptual Design Report Documents... · NGNP and Hydrogen Production Preconceptual Design Report NGNP-20-RPT-003 Special Study 20.3 – High Temperature

20.3

/20.4

: P

art

4 -

12/6

/2006

15

Op

tio

n 5

:O

pti

on

5:

Bo

tto

min

g S

team

Cycle

, S

eri

es IH

XB

ott

om

ing

Ste

am

Cycle

, S

eri

es IH

X

PB

MR

Ox

yg

en

Re

co

ve

ryH

yd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

Deco

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

Ox

yg

en

Re

co

ve

ryH

yd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

Deco

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

Meta

lo

rS

iCIH

X

SG

HP

TIP

TL

PT

~

Bleed Flow Bleed Flow

Co

nd

en

ser

SG

SG

HP

TIP

TL

PT

~

Bleed Flow Bleed Flow

Co

nd

en

ser

Page 291: NGNP and Hydrogen Production Preconceptual Design Report Documents... · NGNP and Hydrogen Production Preconceptual Design Report NGNP-20-RPT-003 Special Study 20.3 – High Temperature

20.3

/20.4

: P

art

4 -

12/6

/2006

16

Op

tio

n 5

:O

pti

on

5:

Bo

tto

min

g S

team

Cycle

, S

eri

es IH

XB

ott

om

ing

Ste

am

Cycle

, S

eri

es IH

X

Key F

eatu

res

•S

ma

ll t

o m

ed

ium

(U

p t

o ~

20

0M

Wt)

to

pp

ing

IH

XO

ption t

o u

se liq

uid

salt S

HT

S w

ork

ing f

luid

Option t

o o

pera

te w

ithout

IHX

•B

ott

om

ing

ste

am

ge

ne

rato

r

700ºC

-950ºC

desig

n b

asis

, nom

inal depends

on I

HX

rating

Read

iness

•C

on

ve

nti

on

al

ste

am

cyc

le,

wit

h s

tea

m

gen

era

tor

based

on

earl

ier

HT

GR

sn

o R

&D

•O

pti

on

to

op

era

te s

tea

m c

yc

le w

ith

ou

t IH

X

ins

tall

ed

•S

ign

ific

an

t m

ism

atc

h b

etw

een

pri

mary

/ seco

nd

ary

flo

ws

Prim

ary

sid

e o

f IH

X m

ust

be d

esig

ned f

or

full

flow

(pote

ntial is

sues w

ith b

ypass/h

ot

str

eaks)

Mis

matc

h d

ecre

ases a

s I

HX

pow

er

incre

ases

SH

TS

circula

tor

tem

pera

ture

an issue

Su

pp

ort

of

Co

mm

erc

ial

Ap

pli

ca

tio

ns

•L

arg

er

en

gin

eeri

ng

scale

dem

on

str

ati

on

s o

f H

yS

/S-I

fe

as

ible

(u

p t

o ~

10

0+

MW

t)

Possib

ly e

ven larg

er

with r

eductions o

f S

C

effic

iency

•L

ow

NH

S c

om

mo

nality

wit

h c

om

merc

ial P

HP

May b

e inadequate

as p

roto

type for

desig

n

cert

ific

ation o

f P

HP

com

merc

ial pla

nts

Perf

orm

an

ce

•P

CS

tem

pera

ture

s c

on

sis

ten

t w

ith

mo

dern

ste

am

co

nd

itio

ns

Ste

am

cycle

not

as s

ensitiv

e t

o t

herm

al ra

ting

as G

T c

ycle

s

•S

team

cycle

pro

vid

es a

ltern

ate

heat

sin

k

(co

ole

rs)

for

off

-no

rma

l e

ve

nts

Requires o

pera

tional P

HT

S

•P

ote

nti

al

for

wa

ter

ing

ress

mu

st

be

co

ns

ide

red

Co

st

•C

ap

ital

Alo

ng w

ith O

ptions 1

and 2

, am

ong the low

est

capital cost

options

Sm

all

IHX

im

plie

s m

odest

repla

cem

ent

capital

cost

•O

pe

rati

ng

Pote

ntial fo

r re

asonable

effic

iency,

hig

h

availa

bili

ty t

o m

axim

ize c

ost

offsets

via

ele

ctr

ic

sale

s

PC

S m

ain

tenance c

onventional

Page 292: NGNP and Hydrogen Production Preconceptual Design Report Documents... · NGNP and Hydrogen Production Preconceptual Design Report NGNP-20-RPT-003 Special Study 20.3 – High Temperature

20.3

/20.4

: P

art

4 -

12/6

/2006

17

Op

tio

n 6

:O

pti

on

6:

Seco

nd

ary

Ste

am

Cycle

, S

eri

es P

CH

XS

eco

nd

ary

Ste

am

Cyc

le, S

eri

es P

CH

X

PB

MR

Ox

yg

en

Re

co

ve

ryH

yd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

Deco

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

Ox

yg

en

Re

co

ve

ryH

yd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

Deco

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

Meta

l

IHX

Meta

lo

rS

iCIH

X

SG

HP

TIP

TL

PT

~

Bleed Flow Bleed Flow

Co

nd

en

ser

SG

SG

HP

TIP

TL

PT

~

Bleed Flow Bleed Flow

Co

nd

en

ser

Page 293: NGNP and Hydrogen Production Preconceptual Design Report Documents... · NGNP and Hydrogen Production Preconceptual Design Report NGNP-20-RPT-003 Special Study 20.3 – High Temperature

20.3

/20.4

: P

art

4 -

12/6

/2006

18

Op

tio

n 6

:O

pti

on

6:

Seco

nd

ary

Ste

am

Gen

era

tor,

Seri

es P

CH

XS

ec

on

dary

Ste

am

Gen

era

tor,

Seri

es P

CH

X

Key F

eatu

res

•F

ull-s

ize I

HX

tra

nsfe

rs a

ll r

eacto

r h

eat

to

SH

TS

•S

ma

ll t

o M

ed

ium

PC

HX

as

to

pp

ing

cyc

leU

p t

o ~

200M

Wt

•S

team

gen

era

tor

as b

ott

om

ing

cycle

700ºC

-900ºC

desig

n b

asis

, nom

inal depends

on P

CH

X r

ating

•P

CH

X/P

CS

lik

ely

to

be c

o-l

ocate

d

Read

iness

•C

on

ve

nti

on

al

ste

am

cyc

le,

wit

h s

tea

m

gen

era

tor

based

on

earl

ier

HT

GR

sn

o R

&D

•O

pti

on

to

op

era

te P

CS

wit

ho

ut

PC

HX

in

sta

lle

d

•L

arg

e I

HX

po

ses g

reate

st

ch

allen

ge t

o

read

iness

Su

pp

ort

of

Co

mm

erc

ial

Ap

pli

ca

tio

ns

•L

arg

er

en

gin

eeri

ng

scale

dem

on

str

ati

on

s o

f H

yS

/S-I

fe

as

ible

(u

p t

o ~

10

0M

Wt)

Possib

ly e

ven larg

er

with r

eductions o

f S

C

effic

iency

•H

igh

NH

S c

om

mo

nality

wit

h c

om

merc

ial

PH

P

If s

uccessfu

l, r

esolv

es I

HX

issue f

or

com

merc

ial pla

nts

Adequate

pro

toty

pe f

or

desig

n c

ert

ific

ation o

f P

HP

com

merc

ial pla

nts

Perf

orm

an

ce

•P

CS

tem

pera

ture

s c

on

sis

ten

t w

ith

mo

dern

ste

am

co

nd

itio

ns

Ste

am

cycle

not

as s

ensitiv

e t

o t

herm

al ra

ting

as G

T c

ycle

s

•S

team

cycle

pro

vid

es a

ltern

ate

heat

sin

k f

or

off

-no

rma

l e

ve

nts

Requires o

pera

tional P

HT

S a

nd S

HT

S

•S

ign

ific

an

t a

va

ila

bil

ity r

isk

as

so

cia

ted

wit

h

po

ten

tia

l fo

r IH

X l

ea

ks

Co

st

•C

ap

ital

Larg

e I

HX

im

plie

s p

ote

ntial fo

r hig

h

repla

cem

ent

capital costs

–M

ay b

e m

itig

ate

d b

y s

ele

ction o

f cera

mic

m

ate

rial and/o

r split

section d

esig

n

•O

pe

rati

ng

Low

er

effic

iency, availa

bili

ty r

isk m

ay r

educe

cost

offsets

via

ele

ctr

ic s

ale

s

Tra

deoff o

f IH

X/c

ircula

tor

vs.

PC

S

ma

inte

nance

co

sts

Page 294: NGNP and Hydrogen Production Preconceptual Design Report Documents... · NGNP and Hydrogen Production Preconceptual Design Report NGNP-20-RPT-003 Special Study 20.3 – High Temperature

20.3

/20.4

: P

art

4 -

12/6

/2006

19

Cy

cle

L

Cy

cle

L ––

Ra

nk

ine

Cy

cle

Pa

ram

ete

rs

Ra

nk

ine

Cy

cle

Pa

ram

ete

rs

00-- 1

0 M

W H

10 M

W H

22P

lan

t S

ize

Pla

nt

Siz

e

•R

an

kin

e p

lan

t siz

ed

fo

r 526 M

W (

Ran

kin

e C

ycle

Desig

n p

oin

t)

•S

team

Tu

rbin

e e

ffic

ien

cie

s -

89

%

•R

an

kin

e c

ycle

eff

icie

nc

y -

43

%

Page 295: NGNP and Hydrogen Production Preconceptual Design Report Documents... · NGNP and Hydrogen Production Preconceptual Design Report NGNP-20-RPT-003 Special Study 20.3 – High Temperature

20.3

/20.4

: P

art

4 -

12/6

/2006

20

Cy

cle

L

Cy

cle

L ––

Ra

nk

ine

Cy

cle

Pa

ram

ete

rs

Ra

nk

ine

Cy

cle

Pa

ram

ete

rs

200 M

W H

200 M

W H

22P

lan

t S

ize

Pla

nt

Siz

e

•R

an

kin

e p

ow

er

level -

326 M

W (

Ran

kin

e C

ycle

Off

-desig

n p

oin

t)

•S

team

Tu

rbin

e e

ffic

ien

cie

s -

75

% (

Off

-desig

n)

•R

an

kin

e c

ycle

eff

icie

ncy 3

7%

(A

ssu

me a

6%

Ran

kin

e C

ycle

eff

icie

ncy d

ecre

ase a

t 326 M

W)

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21

Cy

cle

LC

yc

le L

Infl

ue

nc

e o

f H

yd

rog

en

Pla

nt

Siz

eIn

flu

en

ce

of

Hy

dro

ge

n P

lan

t S

ize

•S

en

sit

ivit

y o

f R

an

kin

e C

ycle

eff

icie

ncy t

o a

ch

an

ge i

n t

he H

yd

rog

en

pla

nt

siz

e (

Ra

nk

ine

cy

cle

de

sig

n p

oin

t =

0 M

Wt

H2)

35

36

37

38

39

40

41

42

43

040

80

120

160

200

240

Hyd

rog

en

Pla

nt

Siz

e (

MW

t)

Rankine Cycle Efficiency [%]

Rankin

e C

ycle

Effi

cie

ncy

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22

Cy

cle

K

Cy

cle

K ––

Ra

nk

ine

Cy

cle

R

an

kin

e C

yc

le

SG

Pin

ch

Te

mp

era

ture

S

G P

inc

h T

em

pe

ratu

re (

20.3

)(2

0.3

)

H2

-2

00 M

W (

Ran

kin

e 3

25 M

W)

SG

Pin

ch

Tem

p o

f 25°C

H2

-2

50 M

W (

Ran

kin

e 2

75 M

W)

SG

Pin

ch

Tem

p o

f 7°C

•S

G P

inch

Tem

pera

ture

: 93°C

(0

MW

), 2

5°C

(2

00

MW

), 7°C

(250 M

W)

•R

an

kin

e p

lan

t s

ize

d f

or

52

6 M

W (

0-1

0 M

W H

2p

lan

t)

•M

axim

um

H2

pla

nt

po

wer

level ~

200 M

W

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23

Pro

ce

ss

He

at/

PC

SP

roc

es

s H

ea

t/P

CS

Co

nfi

gu

rati

on

Hie

rarc

hy

Co

nfi

gu

rati

on

Hie

rarc

hy

PB

MR

Ind

irect

PC

SD

ire

ct

PC

S

Bra

yto

n C

yc

le

Seri

es o

r P

ara

llel

IHX

Pro

cess I

nte

gra

ted

or

No

PC

S

Ste

am

Cyc

le

Seco

nd

ary

PC

S

Ste

am

Cyc

le

Gas T

urb

ine

Co

mb

ine

d C

yc

le

Seri

es o

r P

ara

llel

IHX

Bra

yto

n C

yc

le

Seri

es o

r P

ara

llel

IHX

Gas T

urb

ine

Co

mb

ine

d C

yc

le

Seri

es o

r P

ara

llel

IHX

Pri

mary

/Seco

nd

ary

SG

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24

Op

tio

n 7

:O

pti

on

7:

PC

S In

teg

rate

d w

ith

Pro

cess

PC

S In

teg

rate

d w

ith

Pro

cess

PB

MR

Ox

yg

en

Re

co

ve

ryH

yd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

Deco

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

Ox

yg

en

Re

co

ve

ryH

yd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

Deco

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

Fu

lly I

nte

gra

ted

PC

S

SG

SG

HP

TL

PT

~ Co

nd

en

se

r

Pre

heate

r

Pro

cess P

lan

t B

att

ery

Lim

its

Meta

l

IHX

Meta

lo

rS

iCIH

X

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25

Op

tio

n 7

:O

pti

on

7:

PC

S In

teg

rate

d w

ith

Pro

cess

PC

S In

teg

rate

d w

ith

Pro

cess

Key F

eatu

res

•F

ull-s

ize I

HX

tra

nsfe

rs a

ll r

eacto

r h

eat

to

SH

TS

•F

ull

-siz

e P

CH

X t

ran

sfe

rs a

ll t

he

rma

l e

nerg

y t

o

pro

cess

•S

team

cycle

-based

PC

S i

nte

gra

ted

wit

h

pro

cess

Siz

e/c

onfigura

tion is p

rocess d

ependent

Read

iness

•L

arg

e I

HX

po

ses g

reate

st

ch

allen

ge t

o

read

iness

•R

eq

uir

es

pro

ce

ss

av

ail

ab

ilit

y f

or

op

era

tio

n

•M

inim

um

fle

xib

ilit

y f

or

de

mo

ns

tra

tio

n o

f m

ult

iple

ap

pli

ca

tio

ns

Requires r

econfigura

tion o

f both

pro

cess a

nd

PC

S for

indiv

idual applic

ations

Su

pp

ort

of

Co

mm

erc

ial

Ap

pli

ca

tio

ns

•N

ot

co

nsis

ten

t w

ith

HT

E a

rch

itectu

re

•U

p t

o f

ull

-sca

le d

em

on

str

ati

on

s o

f P

HP

•H

igh

NH

S c

om

mo

nality

wit

h c

om

merc

ial

PH

P

If s

uccessfu

l, r

esolv

es I

HX

issue f

or

com

merc

ial pla

nts

Best

pro

toty

pe f

or

desig

n c

ert

ific

ation o

f P

HP

com

merc

ial pla

nts

Perf

orm

an

ce

•P

roto

typ

ica

l o

f c

om

merc

ial

ap

pli

ca

tio

ns

•P

rov

isio

ns

fo

r a

ltern

ate

he

at

sin

k i

n S

HT

S o

r p

rocess a

re p

rocess d

ep

en

den

tR

equires o

pera

tional P

HT

S

•S

ign

ific

an

t a

va

ila

bil

ity r

isk

as

so

cia

ted

wit

h

po

ten

tial

for

IHX

leaks,

pro

cess-r

ela

ted

o

uta

ge

s

Co

st

•C

ap

ital

Added c

ost

for

multip

le d

em

onstr

ations

Larg

e I

HX

im

plie

s p

ote

ntial fo

r hig

h

repla

cem

ent

capital costs

–M

ay b

e m

itig

ate

d b

y s

ele

ction o

f cera

mic

m

ate

rial and/o

r split

section d

esig

n

•O

pe

rati

ng

Low

effic

iency, availa

bili

ty lik

ely

to m

inim

ize

cost

offsets

via

ele

ctr

ic s

ale

s

PC

S m

ain

tenance c

osts

moved t

o p

rocess

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26

Ou

tlin

eO

utl

ine

•O

bje

cti

ve a

nd

Sco

pe

•S

tud

y In

pu

tsC

om

merc

ial applic

ations a

nd p

erf

orm

ance r

equirem

ents

Key N

GN

P H

TS

dem

onstr

ation o

bje

ctives

Key H

TS

functional re

quirem

ents

Oth

er

input re

quirem

ents

and d

ata

•S

cre

en

ing

Cri

teri

a

•P

ow

er

Co

nvers

ion

Syste

m O

pti

on

s (

20.4

)

•H

2P

rod

ucti

on

Un

it S

ize (

20.7

)

•IH

X/H

igh

-Tem

pera

ture

Mate

rials

•S

eco

nd

ary

Wo

rkin

g F

luid

•H

TS

Co

nfi

gu

rati

on

Op

tio

ns

•R

eco

mm

en

ded

HT

S C

on

fig

ura

tio

n

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27

Re

co

mm

en

da

tio

nR

ec

om

me

nd

ati

on

Th

e r

eco

mm

en

ded

HT

S is O

pti

on

6:

•F

ull-s

ize I

HX

best

rep

resen

ts

co

mm

erc

ial ap

plicati

on

s a

nd

pro

vid

es

op

tim

um

ba

sis

fo

r d

es

ign

ce

rtif

ica

tio

n

of

pro

cess h

eat

ap

plicati

on

s

•G

T/G

TC

C c

om

merc

ial

ap

plicati

on

s

ad

eq

uate

ly s

up

po

rted

by D

PP

in

So

uth

A

fric

a

•S

tea

m c

yc

le p

rov

ide

s g

rea

ter

fle

xib

ilit

y

for

bala

ncin

g n

eed

s o

f d

em

on

str

ati

on

lo

op

an

d P

CS

Wid

e r

ange o

f energ

y a

llocation to

PC

HX

vs. P

CS

(0 –

200M

Wt)

Best

pro

tects

IH

X a

gain

st

transie

nt

eve

nts

(te

mp

era

ture

, p

ressu

re)

•M

inim

ize

s R

&D

an

d r

isk

no

t d

ire

ctl

y

asso

cia

ted

wit

h p

rocess h

eat

ob

jecti

ves

Op

tio

n 6

: S

eco

nd

ary

Ste

am

Cycle

, S

eri

es P

CH

XO

pti

on

6:

Seco

nd

ary

Ste

am

Cycle

, S

eri

es P

CH

X

PB

MR

Ox

yg

en

Rec

overy

Hyd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

De

co

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

Ox

yg

en

Rec

overy

Hyd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

De

co

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

Meta

l

IHX

Meta

lo

rS

iCIH

X

SG

HP

TIP

TL

PT

~

Bleed Flow Bleed Flow

Co

nd

en

ser

SG

SG

HP

TIP

TL

PT

~

Bleed Flow Bleed Flow

Co

nd

en

ser

PB

MR

Ox

yg

en

Rec

overy

Hyd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

De

co

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

Ox

yg

en

Rec

overy

Hyd

rog

en

Ge

nera

tio

n

Ele

ctr

oly

ze

r

Su

lfu

ric

Acid

De

co

mp

osit

ion

Su

lfu

ric

Ac

id

Pre

he

ati

ngH2

O2

H2O

Po

wer

Meta

l

IHX

Meta

lo

rS

iCIH

X

Meta

l

IHX

Meta

l

IHX

Meta

lo

rS

iCIH

X

Meta

lo

rS

iCIH

X

Meta

lo

rS

iCIH

X

SG

HP

TIP

TL

PT

~

Bleed Flow Bleed Flow

Co

nd

en

ser

SG

SG

HP

TIP

TL

PT

~

Bleed Flow Bleed Flow

Co

nd

en

ser

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28

Op

tio

n 6

Evalu

ati

on

Op

tio

n 6

Evalu

ati

on

Att

rib

ute

Imp

ort

an

ce

Assessm

en

t

•R

ead

iness

Ab

ilit

y t

o m

ee

t N

GN

P t

ime

lin

e (

sta

rtu

p:

20

16

-201

8)

Hig

h7

-8

NG

NP

R&

D R

equirem

ents

/Cost/R

isk

Med

5

Supplie

r In

frastr

uctu

re D

evelo

pm

ent

Low

10

•S

up

po

rt o

f C

om

merc

ial

Ap

pli

ca

tio

ns

Ad

eq

uate

ly d

em

on

str

ate

s c

om

merc

ial

pro

cess h

eat

Hig

h10

ap

pli

ca

tio

ns

NH

S c

om

mo

na

lity

wit

h c

om

merc

ial

pro

du

cts

Hig

h8

Ca

n s

erv

e a

s p

roc

ess h

ea

t p

roto

typ

e f

or

de

sig

n c

ert

ific

ati

on

Hig

h1

0

Fle

xib

ility

for

dem

onstr

ating m

ultip

le a

pplic

ations

Med

Fle

xib

ility

for

ultim

ate

convers

ion to full-

scale

H2 p

roduction

Med

10

•P

erf

orm

an

ce

Ab

ilit

y t

o m

ee

t o

pe

rati

on

al

pe

rfo

rma

nc

e g

oa

lsH

igh

8-9

Effic

iency

Low

7

Opera

bili

tyM

ed

9-1

0

Availa

bili

tyLow

6

•C

ost

NG

NP

Ca

pit

al

Co

st

Hig

h7

NG

NP

Opera

ting C

ost

Low

8