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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
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
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 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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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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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
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
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
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
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
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
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
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.
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
.
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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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
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
.
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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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.
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
ddre
ssed
Ove
rall
: P
ote
ntial fo
r S
HT
S leaks into
pri
mary
sys
tem
a d
isadvanta
ge for
CO
2, pote
ntially
a m
ajo
r is
sue for
LS
. L
S w
ould
allo
w g
rea
ter
dis
tance
be
twee
n r
ea
cto
r a
nd
pro
cess.
Ta
ble
20
.3.2
-11
E
con
om
ics
Heliu
mC
O2
Liq
uid
Salt
B
ase
fo
r co
mp
ariso
n
Tra
deoff o
f la
rger
heat exchangers
(IH
X,
PC
HX
) vs
. re
du
ce
d p
um
pin
g c
osts
F
urt
her
eva
lua
tio
n r
equ
ire
d to
dete
rmin
e n
et im
pact
C
ap
ita
l cost lik
ely
to
be
lo
we
r
IH
X, P
CH
X, m
ain
SH
TS
com
ponents
w
ill b
e s
malle
r, less e
xpensiv
e
H
ow
ever,
an o
ffset w
ill b
e a
dditio
nal
auxili
ary
syste
ms r
equired for
meltin
g,
LS
te
mp
era
ture
con
tro
l
C
ap
ita
l cost a
dva
nta
ge
will
in
cre
ase
w
ith d
ista
nce b
etw
een IH
X a
nd P
CH
X
O
pera
ting c
osts
may b
e h
igher
or
low
er
L
ow
er
pum
pin
g c
osts
(d
ista
nce
a k
ey
pa
ram
ete
r)
H
ighe
r m
ain
ten
ance
costs
Ove
rall
: P
ote
ntially
sig
nific
ant capital c
ost advanta
ge for
LS
, but opera
ting c
ost tr
adeoffs u
ncert
ain
.
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
54 o
f 150
Tab
le 2
0.3
.2-1
2
R&
D R
equ
irem
ents
Heliu
mC
O2
Liq
uid
Salt
IH
X
P
ote
ntial exis
ts to u
se a
me
talli
c IH
X
IH
X c
ore
to m
eta
l tr
ansitio
ns
A
pplie
s to c
era
mic
/CF
RC
IH
X
Is
ola
tio
n v
alv
es
P
CH
X
IH
X
M
ate
ria
l co
mp
atib
ility
an
issu
e fo
r m
eta
llic H
Xs
IH
X c
ore
to m
eta
l tr
ansitio
ns
A
pplie
s to c
era
mic
/CF
RC
IH
X
Is
ola
tio
n v
alv
es
P
CH
X
IH
X
W
ill a
lmost cert
ain
ly r
equire
cera
mic
/CF
RC
IH
X
IH
X c
ore
to m
eta
l tr
ansitio
ns
A
pplie
s to c
era
mic
/CF
RC
IH
X
Is
ola
tio
n v
alv
es
S
HT
S p
ipin
g a
nd
insu
lation
P
CH
X
P
um
p a
nd
sea
ls
Overa
ll:
R&
D s
om
ew
ha
t gre
ate
r fo
r C
O2 if m
eta
llic H
Xs a
re feasib
le. L
S r
equires m
ajo
r R
&D
initia
tive.
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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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.
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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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
(µ
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
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
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
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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PBMR
Oxygen RecoveryHydrogen Generation
Electrolyzer
Sulfuric Acid
DecompositionSulfuric Acid
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H2
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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
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PT ~GBCOMP PT ~GBCOMP
SGSG
HPT IPT LPT ~
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Precooler-1
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Oxygen RecoveryHydrogen Generation
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DecompositionSulfuric Acid
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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
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Metalor
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PT ~GBCOMP
SG
HPT IPT LPT ~
RHX
Condenser
Precooler-1
Precooler-2
Ble
ed
Flo
w
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PT ~GBCOMP PT ~GBCOMP
SGSG
HPT IPT LPT ~
RHXRHX
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
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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PBMROxygen Recovery
Hydrogen Generation
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Oxygen RecoveryHydrogen Generation
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Sulfuric Acid
DecompositionSulfuric Acid
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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
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PT ~GBCOMP PT ~GBCOMP
SGSG
HPT IPT LPT ~
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PBMROxygen Recovery
Hydrogen Generation
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Sulfuric Acid
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H2
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Oxygen RecoveryHydrogen Generation
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H2
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PowerRHX
Precooler
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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
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PT ~GBCOMP
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HPT IPT LPT ~
RHX
Condenser
Precooler-1
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Ble
ed
Flo
w
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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
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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PBMR
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Metalor
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SG
HPT IPT LPT ~
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HPT IPT LPT ~
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leed
Flo
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Condenser
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Oxygen RecoveryHydrogen Generation
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Power
Oxygen RecoveryHydrogen Generation
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H2
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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
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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.
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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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.
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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Metalor
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HPT IPT LPT ~
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HPT IPT LPT ~
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Oxygen RecoveryHydrogen Generation
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SiCIHX
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IHX
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IHX
Metalor
SiCIHX
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SiCIHX
Metalor
SiCIHX
SG
HPT IPT LPT ~
Ble
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Flo
wB
leed
Flo
w
CondenserSGSG
HPT IPT LPT ~
Ble
ed
Flo
wB
leed
Flo
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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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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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35
36
37
38
39
40
41
42
43
0 40 80 120 160 200 240
Hydrogen Plant Size (MWt)
Ran
kin
e C
ycle
Eff
icie
ncy [
%]
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
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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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.
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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
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
146 of 150
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.
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
147 of 150
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]
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
148 o
f 150
Ta
ble
20
.3.4
-8
Ev
alu
ati
on
of
HT
S C
on
fig
ura
tio
n O
pti
on
s
Ev
al
Sc
ore
Ev
al
Sco
reE
val
Sc
ore
Ev
al
Sc
ore
Ev
al
Sc
ore
Ev
al
Sc
ore
Ev
al
Sc
ore
Re
ad
ine
ss
Ab
ility
to m
ee
t N
GN
P t
ime
line
(sta
rtu
p: 2
016
-
20
18)
Hig
h8
24
82
45
15
51
51
03
07
21
13
NG
NP
R&
D R
equ
irem
en
ts/C
ost/
Ris
kM
ed
612
61
25
10
51
01
02
07
14
12
Su
pp
lier
Infr
astr
uctu
re D
evelo
pm
en
tL
ow
33
33
99
99
11
77
10
10
Su
pp
ort
of
Co
mm
erc
ial
Ap
pli
ca
tio
ns
Ad
eq
uate
ly d
em
on
str
ate
s c
om
merc
ial pro
ce
ss
he
at
Hig
h1
31
36
18
61
83
98
24
10
30
NH
S c
om
mon
alit
y w
ith
co
mm
erc
ial pro
du
cts
Hig
h2
62
68
24
82
41
37
21
10
30
Ca
n s
erv
e a
s p
roce
ss h
ea
t pro
toty
pe
fo
r d
esig
n
cert
ific
atio
nH
igh
13
13
61
86
18
39
82
410
30
Fle
xib
ility
fo
r d
em
on
str
atin
g m
ultip
le a
pplic
atio
ns
Me
d5
10
51
04
84
87
14
91
81
2
Fle
xib
ility
fo
r u
ltim
ate
co
nve
rsio
n to
fu
ll-sca
le H
2
pro
du
ctio
nM
ed
12
12
61
26
12
71
49
18
10
20
Pe
rfo
rma
nce
Ab
ility
to m
ee
t o
pera
tion
al p
erf
orm
an
ce
go
als
Hig
h4
12
39
72
18
24
72
11
03
01
3
Eff
icie
ncy
Low
77
88
55
66
88
11
10
10
Op
era
bili
tyM
ed
816
12
24
36
10
20
91
81
2
Ava
ilab
ility
Low
88
88
55
66
10
10
77
11
Co
st
NG
NP
Ca
pita
l C
ost
Hig
h8
24
92
76
18
61
81
03
07
21
13
NG
NP
Op
era
ting
Co
st
Low
88
99
66
77
10
10
88
11
To
tals
13
81
26
173
18
119
92
32
14
7
Att
rib
ute
Imp
ort
an
ce
As
ses
sm
en
t o
f O
pti
on
s
Op
tio
n 1
Op
tio
n 2
Op
tio
n 3
Op
tio
n 4
Op
tio
n 5
Op
tio
n 6
Op
tio
n 7
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
149 of 150
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.
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
150 of 150
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
APPENDIX 20.3.1: SPECIAL STUDY 20.3.1 SLIDES
PART 1 – INPUTS AND CRITERIA
20.3
/20.4
: P
art
1-
R1
-12/1
8/2
006
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 1
P
art
1 ––
Inp
uts
an
d C
rite
ria
Inp
uts
an
d C
rite
ria
De
ce
mb
er
6,
20
06
De
ce
mb
er
6,
20
06
20.3
/20.4
: 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
20.3
/20.4
: P
art
1-
R1
-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
20.3
/20.4
: P
art
1-
R1
-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
mate
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:
Evalu
ate
an
d s
ele
ct
refe
ren
ce H
TS
co
ncep
t
20.3
/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
20.3
/20.4
: P
art
1-
R1
-12/1
8/2
006
6
Pro
sp
ecti
ve C
om
merc
ial A
pp
licati
on
sP
rosp
ecti
ve C
om
merc
ial A
pp
licati
on
s
•P
BM
R E
lectr
ic P
lan
t A
pp
licati
on
s
Multi-M
odule
Pow
er
Pla
nt
(MM
P)
–B
rayto
n C
ycle
–C
om
merc
ial fo
llow
-on to D
em
onstr
ation P
ow
er
Pla
nt (D
PP
)
Ad
va
nce
d E
lectr
ic P
ow
er
Pla
nt
(AE
P)
–G
as-t
urb
ine c
om
bin
ed c
ycle
pow
er
pla
nt (G
TC
C)
from
20.4
•P
roc
es
s H
ea
t A
pp
lic
ati
on
s
H2/S
yngas v
ia S
team
-Meth
ane R
efo
rmin
g (
SM
R)
H2
via
Hyb
rid
Su
lfu
r (H
yS
) P
roce
ss (R
ef.
1)
H2
via
Sulfur-
Iodin
e (
S-I
) P
rocess (R
ef.
2)
H2
via
Hig
h T
em
pe
ratu
re E
lectr
oly
sis
(H
TE
) (R
ef. 3
)
20.3
/20.4
: P
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
Pro
cess P
lan
t B
att
ery
Lim
its
20.3
/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)
20.3
/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)
20.3
/20.4
: 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
20.3
/20.4
: P
art
1-
R1
-12/1
8/2
006
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
20.3
/20.4
: P
art
1-
R1
-12/1
8/2
006
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
20.3
/20.4
: P
art
1-
R1
-12/1
8/2
006
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
20.3
/20.4
: P
art
1-
R1
-12/1
8/2
006
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
20.3
/20.4
: P
art
1-
R1
-12/1
8/2
006
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
20.3
/20.4
: P
art
1-
R1
-12/1
8/2
006
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
20.3
/20.4
: P
art
1-
R1
-12/1
8/2
006
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)
20.3
/20.4
: P
art
1-
R1
-12/1
8/2
006
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
20.3
/20.4
: P
art
1-
R1
-12/1
8/2
006
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.
20.3
/20.4
: P
art
1-
R1
-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
20.3
/20.4
: P
art
1-
R1
-12/1
8/2
006
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
20.3
/20.4
: P
art
1-
R1
-12/1
8/2
006
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.
20.3
/20.4
: P
art
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
APPENDIX 20.3.1: SPECIAL STUDY 20.3.1 SLIDES
PART 2 – POWER CONVERSION SYSTEM OPTIONS
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
$$
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
)
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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%
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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)
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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)
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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)
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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
20.3
/20.4
: P
art
2 -
12/6
/2006
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)
APPENDIX 20.3.1: SPECIAL STUDY 20.3.1 SLIDES
PART 3 – HPU, IHX/MATERIALS, SHTS WORKING FLUID
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
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
•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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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%
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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)
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
12
Pla
teP
late
-- Fin
HX
Fin
HX
(In
gers
oll R
an
d E
nerg
y S
yste
ms)
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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)
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
14
He
at
Ex
ch
an
ge
r M
etr
ics
He
at
Ex
ch
an
ge
r M
etr
ics
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
16
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)
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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)
20.3
/20.4
: P
art
3-R
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12/1
6/2
006
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
20.3
/20.4
: P
art
3-R
1 -
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6/2
006
22
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
20.3
/20.4
: P
art
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006
23
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)
20.3
/20.4
: P
art
3-R
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6/2
006
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
20.3
/20.4
: P
art
3-R
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12/1
6/2
006
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
27
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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
20.3
/20.4
: P
art
3-R
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6/2
006
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.
20.3
/20.4
: P
art
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006
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
20.3
/20.4
: P
art
3-R
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006
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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.
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
35
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
20.3
/20.4
: P
art
3-R
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6/2
006
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
20.3
/20.4
: P
art
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6/2
006
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
20.3
/20.4
: P
art
3-R
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6/2
006
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
20.3
/20.4
: P
art
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6/2
006
39
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
20.3
/20.4
: P
art
3-R
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6/2
006
40
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
20.3
/20.4
: P
art
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6/2
006
41
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
20.3
/20.4
: P
art
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006
42
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
43
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
+
-
--
20.3
/20.4
: P
art
3-R
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006
44
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
20.3
/20.4
: P
art
3-R
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006
45
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
20.3
/20.4
: P
art
3-R
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12/1
6/2
006
46
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
20.3
/20.4
: P
art
3-R
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12/1
6/2
006
47
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
20.3
/20.4
: P
art
3-R
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6/2
006
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
20.3
/20.4
: P
art
3-R
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6/2
006
49
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
20.3
/20.4
: P
art
3-R
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6/2
006
50
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
20.3
/20.4
: P
art
3-R
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6/2
006
51
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
20.3
/20.4
: P
art
3-R
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6/2
006
52
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
.
20.3
/20.4
: P
art
3-R
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6/2
006
53
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
.
20.3
/20.4
: P
art
3-R
1 -
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6/2
006
54
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
.
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
55
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.
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
56
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
.
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
57
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.
20.3
/20.4
: P
art
3-R
1 -
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6/2
006
58
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.
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
59
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.
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
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
20.3
/20.4
: P
art
3-R
1 -
12/1
6/2
006
61
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
APPENDIX 20.3.1: SPECIAL STUDY 20.3.1 SLIDES
PART 4 – HEAT TRANSPORT SYSTEM OPTIONS
20.3
/20.4
: P
art
4 -
12/6
/2006
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
20.3
/20.4
: P
art
4 -
12/6
/2006
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
20.3
/20.4
: P
art
4 -
12/6
/2006
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
20.3
/20.4
: P
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
20.3
/20.4
: P
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
20.3
/20.4
: P
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
20.3
/20.4
: P
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
20.3
/20.4
: P
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
20.3
/20.4
: P
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
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
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
20.3
/20.4
: P
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
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
20.3
/20.4
: P
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
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
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
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
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
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
%
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)
20.3
/20.4
: P
art
4 -
12/6
/2006
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
20.3
/20.4
: P
art
4 -
12/6
/2006
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
20.3
/20.4
: P
art
4 -
12/6
/2006
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
20.3
/20.4
: P
art
4 -
12/6
/2006
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
20.3
/20.4
: P
art
4 -
12/6
/2006
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
20.3
/20.4
: P
art
4 -
12/6
/2006
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
20.3
/20.4
: P
art
4 -
12/6
/2006
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
20.3
/20.4
: P
art
4 -
12/6
/2006
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