1. September 11, 2000 A. R. Raffray, et al., High Performance Blanket for ARIES-AT Power Plant, SOFT 2000 High Performance Blanket for Aries-AT Power Plant A. R. Raffray 1, L. El-Guebaly 2, S. Gordeev 3, S. Malang 3, E. Mogahed 2, F. Najmabadi 1, I. Sviatoslavsky 2, D. K. Sze 4, M. S. Tillack 1, X. Wang 1, and the ARIES Team 1 University of California, San Diego, 460 EBU-II, La Jolla, CA 92093-0417, USA 2 University of Wisconsin, Fusion Technology Institute, 1500 Engineering Drive, Madison, WI 53706-1687, USA 3 Forschungszentrum Karlsruhe, Postfach 3640, D-76021 Karlsruhe, Germany 4 Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA SOFT 2000 Poster Presentation, Madrid, Spain, September 2000

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

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

4. September 11, 2000 A. R. Raffray, et al., High Performance Blanket for ARIES-AT Power Plant, SOFT 2000 Brayton Cycle Offers Best Near-Term Possibility of Power Conversion with High Efficiency Maximize potential gain from high- temperature operation with SiC f /SiC Compatible with liquid metal blanket through use of IHX High efficiency translates in lower COE and lower heat load

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

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

7. September 11, 2000 A. R. Raffray, et al., High Performance Blanket for ARIES-AT Power Plant, SOFT 2000 SiC f /SiC Properties Used for Design Analysis Consistent with Suggestions from International Town Meeting on SiC f /SiC Held at Oak Ridge National Laboratory in January 2000 * Density ≈ 3200 kg/m 3 Density Factor0.95 Young's Modulus ≈ 200-300 GPa Poisson's ratio0.16-0.18 Thermal Expansion Coefficient4 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 SiC f /SiC-Based Fusion Power Cores,” submitted to Fusion Engineering & Design, August 2000 ** From ARIES-I

8. September 11, 2000 A. R. Raffray, et al., High Performance Blanket for ARIES-AT Power Plant, SOFT 2000 ARIES-AT Machine and Power Parameters Power and Neutronics Parameters Fusion Power 1719 MW Neutron Power 1375 MW Alpha Power 344 MW Current Drive Power25 MW Overall Energy Multiplicat.1.1 Total Thermal Power1897 MW Ave. FW Surf. Heat Flux0.26 MW/m 2 Max. FW Surf. Heat 0.34 MW/m 2 Average Wall Load3.2 MW/m 2 Maximum O/B Wall Load 4.8 MW/m 2 Maximum I/B Wall Load 3.1 MW/m 2 Machine Geometry Major Radius5.2 m Minor Radius1.3 m FW Location at O/B Midplane 6.5 m FW Location at Lower O/B 4.9 m I/B FW Location3.9 m Toroidal Magnetic Field On-axis Magnetic Field5.9 T Magnetic Field at I/B FW 7.9 T Magnetic Field at O/B FW 4.7 T

9. September 11, 2000 A. R. Raffray, et al., High Performance Blanket for ARIES-AT Power Plant, SOFT 2000 Cross-Section and Plan View of ARIES-AT Showing Power Core Components

10. September 11, 2000 A. R. Raffray, et al., High Performance Blanket for ARIES-AT Power Plant, SOFT 2000 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 Coolant Inlet Temperature653 °C Outlet Temperature1100 °C Blanket Inlet Pressure 1 MPa Divertor Inlet Pressure1.7 MPa Mass Flow Rate 22,700 kg/s

11. September 11, 2000 A. R. Raffray, et al., High Performance Blanket for ARIES-AT Power Plant, SOFT 2000 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 SiC f /SiC box and second pass to “superheat” Pb-17Li Maintain blanket SiC f /SiC temperature (~1000°C) < Pb-17Li outlet temperature (~1100°C)

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

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

14. September 11, 2000 A. R. Raffray, et al., High Performance Blanket for ARIES-AT Power Plant, SOFT 2000 Poloidal Distribution of Surface Heat Flux and Neutron Wall Load

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

16. September 11, 2000 A. R. Raffray, et al., High Performance Blanket for ARIES-AT Power Plant, SOFT 2000 Temperature Distribution in ARIES-AT Blanket Based on Moving Coordinate Analysis Pb-17Li Inlet Temp. = 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° Pb-17Li Inlet Temp. = 764 °C Pb-17Li Outlet Temp. = 1100 °C From Plasma Side: - CVD SiC Thickness = 1 mm - SiC f /SiC Thickness = 4 mm (SiC f /SiC k = 20 W/m-K) - Pb-17Li Channel Thick. = 4 mm - SiC/SiC Separ. Wall Thick. = 5 mm (SiC f /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

17. September 11, 2000 A. R. Raffray, et al., High Performance Blanket for ARIES-AT Power Plant, SOFT 2000 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 thickness 116 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)

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

19. September 11, 2000 A. R. Raffray, et al., High Performance Blanket for ARIES-AT Power Plant, SOFT 2000 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/m 2 -K Max. thermal stress = 113 MPa Max. thermal stress = 114 MPa Max. combined stress = 174 MPa (within the 190 MPa limit)

20. September 11, 2000 A. R. Raffray, et al., High Performance Blanket for ARIES-AT Power Plant, SOFT 2000 Develop Plausible Fabrication Procedure and Minimize Joints in High Irradiation Region E.g. First Outboard Region Blanket Segment 1.Manufacture separate halves of the SiC f /SiC poloidal module by SiC f weaving and SiC Chemical Vapor Infiltration (CVI) or polymer process; 2. Manufacture curved section of inner shell in one piece by SiC f 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

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

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

23. September 11, 2000 A. R. Raffray, et al., High Performance Blanket for ARIES-AT Power Plant, SOFT 2000 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 T interface at the expense of additional heat transfer from outlet Pb-17Li to inlet Pb-17Li and increase in Pb-17Li T inlet Very difficult to achieve maximum Pb-17Li /SiC T interface < Pb-17Li T outlet However, manifold flow in region with very low or no radiation Set manifold annular dimensions to miminimize  T bulk while maintaining a reasonable  P

24. September 11, 2000 A. R. Raffray, et al., High Performance Blanket for ARIES-AT Power Plant, SOFT 2000 Typical ARIES-AT Blanket Parameters for Design Point E.g. Blanket Outboard Region 1 Number of Segments32 Number of Modules per Segment6 Module Poloidal Dimension6.8 m Average Module Toroidal Dimension0.19 m First Wall SiC f /SiC Thickness 4 mm First Wall CVD SiC Thickness 1 mm First Wall Annular Channel Thickness4 mm Average Pb-17Li Velocity in First Wall 4.2 m/s First Wall Channel Re3.9 x 10 5 First Wall Channel Transverse Ha4340 MHD Turbulent Transition Re2.2 x 10 6 First Wall MHD Pressure Drop 0.19 MPa Maximum SiC f /SiC Temperature996°C Maximum CVD SiC Temperature 1009 °C Maximum Pb-17Li/SiC Interface Temperature994°C Average Pb-17Li Velocity in Inner Channel 0.11 m/s