september 11, 2000 a. r. raffray, et al., high performance blanket for aries-at power plant, soft...

September 11, 2000A. R. Raffray, et al., High Performance Blanket for ARIES-AT Power Plant, SOFT 2000

High Performance Blanket for Aries-AT Power Plant

A. R. Raffray1, L. El-Guebaly2, S. Gordeev3, S. Malang3,

E. Mogahed2, F. Najmabadi1, I. Sviatoslavsky2, D. K. Sze4,

M. S. Tillack1, X. Wang1, and the ARIES Team

1University of California, San Diego, 460 EBU-II, La Jolla, CA 92093-0417, USA2University of Wisconsin, Fusion Technology Institute, 1500 Engineering Drive,

Madison, WI 53706-1687, USA3Forschungszentrum Karlsruhe, Postfach 3640, D-76021 Karlsruhe, Germany

4Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA

SOFT 2000 Poster Presentation, Madrid, Spain, September 2000


Abstract

The ARIES-AT blanket has been developed with the overall objective of achieving high performance while maintaining attractive safety features, simple design geometry, credible maintenance and fabrication processes, and reasonable design margins as an indication of reliability. The design is based on Pb-17Li as breeder and coolant and SiCf/SiC composite as structural material. This paper describes the results of the design study of this blanket including a discussion of the major SiC composite parameters and properties influencing the design, and a description of the design configuration, analysis results and reference operating parameters.


Blanket Metrics for an Attractive Power Plant as Basis for ARIES-AT Blanket Design

Metrics(not in ranking order)

• High performance

• Tritium self-sufficiency

• Safety

• Waste minimization

• Reliability

• Fabrication

• Maintenance

• Cost

Blanket Design Measures and Parameters• High temperature operation

• Heat load accommodation

• Reasonable pressure drop/pumping power

• Configuration and material choice yielding acceptable TBR

• Low activation material with no serious consequences on blanket and VV from LOFA and LOCA

• Radial segmentation: replaceable regions and lifetime region

• Design simplicity/Minimization of number of components

• Minimization of pressure joints in high irradiation area

• Stress limit margin as reliability measure

• Conservative analysis assumptions

• Develop plausible and reasonable-cost fabrication scheme in parallel with design evolution

• Maintenance scheme compatible with replacement of non-lifetime components


Brayton Cycle Offers Best Near-Term Possibility of Power Conversion with High Efficiency

• Maximize potential gain from high-temperature operation with SiCf/SiC

• Compatible with liquid metal blanket through use of IHX

• High efficiency translates in lower COE and lower heat load

RecuperatorIntercooler 1Intercooler 2

Compressor 1

Compressor 2Compressor 3

HeatRejection

HX

Wnet

Turbine

IntermediateHX

5'

1

22'

38

9

4

7'9'

10

6

T

S

1

2

3

4

5 6 7 8

9 10

PbLi Divertor +Blanket Coolant


Advanced Brayton Cycle Parameters Based on Present or Near Term Technology Evolved with Expert Input

from General Atomics*

• Min. He Temp. in cycle (heat sink) = 35°C

• 3-stage compression with 2 inter-coolers

• Turbine efficiency = 0.93

• Compressor efficiency = 0.88

• Recuperator effectiveness (advanced design) = 0.96

• Cycle He fractional P = 0.03• Intermediate Heat Exchanger

- Effectiveness = 0.9

- (mCp)He/(mCp)Pb-17Li = 1

* R. Schleicher, A. R. Raffray, C. P. Wong, "An Assessment of the Brayton Cycle for High Performance Power Plant," to be presented at the 14th ANS Topical Meeting on Technology of Fusion Energy, October 15-19, 2000, Park City Utah


Compression Ratio is Set for Optimum Efficiency and Reasonable IHX He Inlet Temperature

• IHX He inlet temperature dictates Pb-17Li inlet temperature to power core

Example Design Point:

• Max. Cycle He Temperature

= 1050°C

• Total compression ratio = 3

• Cycle efficiency = 0.585

• Cycle He temp. at HX inlet

= 604°C

• Pb-17 Inlet Temp. to Power

Core = 650°C


SiCf/SiC Properties Used for Design Analysis Consistent with Suggestions from International Town Meeting on SiCf/SiC Held at Oak Ridge National Laboratory in January 2000*

• Density ≈ 3200 kg/m3

• Density Factor 0.95

• Young's Modulus ≈ 200-300 GPa

• Poisson's ratio 0.16-0.18

• Thermal Expansion Coefficient 4 ppm/°C

• Thermal Conductivity in Plane ≈ 20 W/m-K

• Therm. Conductivity through Thickness ≈ 20 W/m-K

• Maximum Allowable Combined Stress ≈ 190 MPa

• Maximum Allowable Operating Temperature ≈ 1000 °C

• Max. Allowable SiC/LiPb Interface Temperature ≈ 1000°C

• Maximum Allowable SiC Burnup ≈ 3%**

* See: http://aries.ucsd.edu/PUBLIC/SiCSiC/, also A. R. Raffray, et al., “Design Material Issues for SiCf/SiC-Based Fusion Power Cores,” submitted to Fusion Engineering & Design, August 2000** From ARIES-I


ARIES-AT Machine and Power Parameters

Power and Neutronics ParametersFusion Power 1719 MW

Neutron Power 1375 MW

Alpha Power 344 MW

Current Drive Power 25 MW

Overall Energy Multiplicat. 1.1

Total Thermal Power 1897 MW

Ave. FW Surf. Heat Flux 0.26 MW/m2

Max. FW Surf. Heat 0.34 MW/m2

Average Wall Load 3.2 MW/m2

Maximum O/B Wall Load 4.8 MW/m2

Maximum I/B Wall Load 3.1 MW/m2

Machine GeometryMajor Radius 5.2 m

Minor Radius 1.3 m

FW Location at O/B Midplane 6.5 m

FW Location at Lower O/B 4.9 m

I/B FW Location 3.9 m

Toroidal Magnetic FieldOn-axis Magnetic Field 5.9 T

Magnetic Field at I/B FW 7.9 T

Magnetic Field at O/B FW 4.7 T


Cross-Section and Plan View of ARIES-AT Showing Power Core Components


Coolant Routing Through 5 Circuits Serviced by Annular Ring Header

Circuit Thermal Power Mass Flow Rate

1. Lower Divertor + Inboard Blanket Region 501 MW 6100 kg/s

2. Upper Divertor +1/2 Outboard Blanket Region I 598 MW 7270 kg/s

3. 1/2 Outboard Blanket Region I 450 MW 5470 kg/s

4. Inboard Hot Shield + 1/2 Outboard Blanket II 182 MW 4270 kg/s

5. Outboard Hot Shield + 1/2 Outboard Blanket II 140 MW 1700 kg/s

Pb-17Li CoolantInlet Temperature 653 °COutlet Temperature 1100 °C Blanket Inlet Pressure 1 MPa Divertor Inlet Pressure 1.7 MPa Mass Flow Rate 22,700 kg/s


ARIES-AT Utilizes a 2-Pass Coolant Approach to Uncouple Structure Temperature from Outlet

Coolant Temperature

• ARIES-AT: 2-pass Pb-17Li flow, first pass to cool SiCf/SiC box and second pass to “superheat” Pb-17Li

• Maintain blanket SiCf/SiC temperature (~1000°C) < Pb-17Li outlet temperature (~1100°C)


ARIES-AT Outboard Blanket Segment Configuration


Multi-Dimensional Neutronics Analysis to Calculate Tritium Breeding Ratio and Heat Generation Profiles

• Latest data and code

• 3-D tritium breeding > 1.1 to account for uncertainties

• Blanket configuration and zone thicknesses adjusted accordingly

• Blanket volumetric heat generation profiles used for thermal-hydraulic analyses


Poloidal Distribution of Surface Heat Flux and Neutron Wall Load

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Poloidal Distance from Lower Outboard (m)

Assuming 10% divertortransport power re-radiation

Assuming no radiationfrom divertor

OUTBOARD INBOARD

DIV.

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

5.50

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Poloidal Distance from Lower Outboard (m)

OUTBOARD INBOARD

DIV.

Average Neutron Wall Load = 3.19 MW/m2


Moving Coordinate Analysis to Obtain Pb-17Li Temperature Distribution in ARIES-AT First Wall

Channel and Inner Channel

• Assume MHD-flow-laminarization effect

• Use plasma heat flux poloidal profile

• Use volumetric heat generation poloidal and radial profiles

• Iterate for consistent boundary conditions for heat flux between Pb-17Li inner channel zone and first wall zone

• Calibration with ANSYS 2-D results

q''plasma

Pb-17Li

q'''LiPb

Out

q''back

vback

vFW

Poloidal

Radial

InnerChannel

First WallChannel

SiC/SiCFirst Wall SiC/SiC Inner Wall


Temperature Distribution in ARIES-AT Blanket Based on Moving Coordinate Analysis

Pb-17Li InletTemp. = 764 °C

Pb-17Li Outlet Temp. = 1100 °C

Max. SiC/PbLi Interf. Temp. = 994 °C

FW Max. CVD and SiC/SiC Temp. = 1009°C° and 996°C°

700

800

900

1000

1100

1200800

900

1000

1100

1200

1

2

3

4

5

6

00.020.040.060.080.1

00.020.040.060.080.1

Radial distance (m)

Poloidaldistance(m)

SiC/SiC

Pb-17Li

• Pb-17Li Inlet Temp. = 764 °C• Pb-17Li Outlet Temp. = 1100 °C

• From Plasma Side: - CVD SiC Thickness = 1 mm - SiCf/SiC Thickness = 4 mm (SiCf/SiC k = 20 W/m-K) - Pb-17Li Channel Thick. = 4 mm - SiC/SiC Separ. Wall Thick. = 5 mm (SiCf/SiC k = 6 W/m-K)

• Pb-17Li Vel. in FW Channel= 4.2 m/s• Pb-17Li Vel. in Inner Chan. = 0.1 m/s

• Plasma heat flux profile assuming no radiation from divertor


Pressure Stress Analysis of Inner Shell of Blanket Module

• Differential pressure stress on blanket module inner shell varies poloidally from ~ 0.25 MPa at the bottom to ~ 0 MPa at the top

• Maximum pressure stress for 0.25 MPa Case:

218 MPa for 5-mm thickness116 MPa for 8-mm thickness

• Use tapered thickness from 7 mm at bottom to ≈ 3 mm at top to maintain comfortable combined stress margin (<< 190 MPa)


Pressure Stress Analysis of Outer Shell of Blanket Module at Segment End of First Outboard Region

• 6 modules per outboard segment • Side walls of all inner modules are pressure

balanced• Side walls of outer modules must be

reinforced to accommodate the Pb-17Li pressure (1 MPa)

• For a 2-cm thick outer module side wall, the maximum pressure stress = 85 MPa

• The side wall can be tapered radially by tailoring the thickness to maintain a uniform stress. This would reduce the SiC volume fraction and benefit tritium breeding.

• The thermal stress at this location is small and the sum of the pressure and thermal stresses is well within the 190 MPa limit.

• The maximum pressure stress at the first

wall is quite low, ~60 MPa.


3-D Thermal Stress Analysis of Toroidal Half of Module in First Outboard Blanket Region

Example case:

• Eff. h in Pb-17Li channel = 15 kW/m2-K

• Max. thermal stress = 113 MPa

• Max. thermal stress = 114 MPa

• Max. combined stress = 174 MPa (within the 190 MPa limit)


Develop Plausible Fabrication Procedure and Minimize Joints in High Irradiation Region

E.g. First Outboard Region Blanket Segment

1. Manufacture separate halves of the SiCf/SiC poloidal module by SiCf weaving and SiC Chemical Vapor Infiltration (CVI) or polymer process;

2. Manufacture curved section of inner shell in one piece by SiCf weaving and SiC Chemical Vapor Infiltration (CVI) or polymer process;

3. Slide each outer shell half over the free-floating inner shell;

4. Braze the two half outer shells together at the midplane;

5. Insert short straight sections of inner shell at each end;

Brazing procedure selected for reliable joint contact area


ARIES-AT First Outboard Region Blanket Segment Fabrication Procedure (cont.)

6. Form a segment by brazing six modules together (this is a bond which is not in contact with the coolant; and

7. Braze caps at upper end and annular manifold connections at lower end of the segment.


Maintenance Methods Allow for End-of-Life Replacement of Individual Components*

* L. M. Waganer, “Comparing Maintenance Approaches for Tokamak Fusion Power Plants,” 14th ANS Topical Meeting on Technology of Fusion Energy, October 15-19, 2000, Park City Utah


Annular Manifold Configuration with Low Temp. Inlet Pb-17Li in Outer Channel and High Temp. Outlet Pb-17Li in Inner Channel

(e.g manifold between ring header and outboard blanket I )

• Reduction in Tinterface at the expense of additional heat transfer from outlet Pb-17Li to inlet Pb-17Li and increase in Pb-17Li Tinlet • Very difficult to achieve maximum Pb-17Li /SiC Tinterface < Pb-17Li Toutlet

• However, manifold flow in region with very low or no radiation• Set manifold annular dimensions to miminimize Tbulk while maintaining a reasonable P


Typical ARIES-AT Blanket Parameters for Design Point

E.g. Blanket Outboard Region 1

• Number of Segments 32

• Number of Modules per Segment 6

• Module Poloidal Dimension 6.8 m

• Average Module Toroidal Dimension 0.19 m

• First Wall SiCf/SiC Thickness 4 mm

• First Wall CVD SiC Thickness 1 mm

• First Wall Annular Channel Thickness 4 mm

• Average Pb-17Li Velocity in First Wall 4.2 m/s

• First Wall Channel Re 3.9 x 105

• First Wall Channel Transverse Ha 4340

• MHD Turbulent Transition Re 2.2 x 106

• First Wall MHD Pressure Drop 0.19 MPa

• Maximum SiCf/SiC Temperature 996°C

• Maximum CVD SiC Temperature 1009 °C

• Maximum Pb-17Li/SiC Interface Temperature 994°C

• Average Pb-17Li Velocity in Inner Channel 0.11 m/s

september 11, 2000 a. r. raffray, et al., high performance blanket for aries-at power plant, soft...

Documents

high performance blanket

blanket design metrics

blanket metrics

design configuration

attractive power plant

high temperature operation

design study

liquid metal blanket