October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE ARIES-AT Blanket and Divertor A. R. Raffray 1, L. El-Guebaly 2, S. Malang 3, I. Sviatoslavsky 2, M. S. Tillack 1, X. Wang 1, and the ARIES Team 1 University of California, San Diego, 460 EBU-II, La Jolla, CA , USA 2 University of Wisconsin, Fusion Technology Institute, 1500 Engineering Drive, Madison, WI , USA 3 Forschungszentrum Karlsruhe, Postfach 3640, D Karlsruhe, Germany Presented at the 14th ANS Topical Meeting on the Technology of Fusion Energy Park City, Utah October 16-19, 2000

A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE Presentation Highlights How Design Was Developed to Meet Overall Objective Outline Power Cycle Material ARIES-AT Reactor Blanket Design and Analysis Divertor Design and Analysis Fabrication Conclusions Overall Objective Develop ARIES-AT Blanket and Divertor Designs to Achieve High Performance while Maintaining: Attractive safety features Simple design geometry Reasonable design margins as an indication of reliability Credible maintenance and fabrication processes Design Utilizes High-Temperature Pb-17Li as Breeder and Coolant and SiC f /SiC Composite as Structural Material

October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE 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 Min. He Temp. in cycle = 35°C 3-stage compression with 2 inter-coolers Turbine efficiency = 0.93 Compressor efficiency = 0.88 Recuperator effectiveness = 0.96 Cycle He fractional  P = 0.03 Max. Cycle He Temperature = 1050°C Cycle efficiency = * R. Schleicher, A. R. Raffray, C. P. Wong, "An Assessment of the Brayton Cycle for High Performance Power Plant," 14th ANS Top. Meet. On TOFE

October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE SiC f /SiC Enables High Temperature Operation and its Low Decay Heat Helps Accommodate LOCA and LOFA Events W/O Serious Consequences on In-Reactor Structure 1,2 Properties Used for Design Analysis Consistent with Suggestions from International Town Meeting on SiC f /SiC Held at Oak Ridge National Laboratory in Jan Density ≈ 3200 kg/m 3 Density Factor0.95 Young's Modulus ≈ GPa Poisson's ratio 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% * 1 D. Henderson, et al, and the ARIES Team, ”Activation, Decay Heat, and Waste Disposal Analyses for ARIES-AT Power Plant," 2 E. Mogahed, et al, and the ARIES Team, ”Loss of Coolant and Loss of Flow Analyses for ARIES-AT Power Plant," 14th ANS T. M. On TOFE 3 See: 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

October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE ARIES-AT Machine and Power Parameters 1,2 Power and Neutronics 3 Parameters Fusion Power 1719 MW Neutron Power 1375 MW Alpha Power 344 MW Current Drive Power25 MW Overall Energy Multiplicat.1.1 Tritium Breeding Ratio1.1 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 1 F. Najmabadi, et al.and the ARIES Team, “Impact of Advanced Technologies on Fusion Power Plant Characteristics,” 14th ANS Top. M.on TOFE 2 R. L. Miller and the ARIES Team, “Systems Context of the ARIES-AT Conceptual Fusion Power Plant,” 14th ANS Top. Meet. On TOFE 3 L. A. El-Guebaly and the ARIES Team, “Nuclear Performance Assessment for ARIES-AT Power Plant,” 14th ANS Top. Meet. On TOFE

October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE Cross-Section and Plan View of ARIES-AT Showing Power Core Components

October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE ARIES-AT Blanket Utilizes a 2-Pass Coolant Approach to Uncouple Structure Temperature from Outlet Coolant Temperature ARIES-AT Outboard Blanket Segment Configuration Maintain blanket SiC f /SiC temperature (~1000°C) < Pb-17Li outlet temperature (~1100°C)

October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE Poloidal Distribution of Surface Heat Flux and Neutron Wall Load

October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE 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

October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE 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

October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE Detailed Stress Analysis of Blanket Module to Maintain Conservative Margins as Reliability Measure e.g. Stress Analysis of Outboard Module 6 modules per outboard segment Side walls of all inner modules are pressure balanced except for outer modules which 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 to reduce the SiC volume fraction and benefit tritium breeding while maintaining a uniform stress The thermal stress at this location is small and the sum of the pressure and thermal stresses is << 190 MPa The maximum pressure stress + thermal stress at the first wall ~ MPa.

October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE Reference Divertor Design Utilizes Pb-17Li as Coolant Single power core cooling system Low pressure and pumping power Analysis indicates that proposed configuration can accommodate a maximum heat flux of ~5-6 MW/m 2 Alternate Options -He-Cooled Tungsten Porous Heat Exchanger (ARIES-ST) -Liquid Wall (Sn-Li) Outlet Pb-17LiManifold Inlet Pb-17LiManifold Tungsten Armor SiC f /SiC Poloidal Channels Outboard Divertor Plate

October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE ARIES-AT Divertor Configuration and Pb-17Li Cooling Scheme Accommodating MHD Effects: Minimize Interaction Parameter (<1) (Strong Inertial Effects) Flow in High Heat Flux Region Parallel to Magnetic Field (Toroidal) Minimize Flow Length and Residence Time Heat Transfer Analysis Based on MHD-Laminarized Flow

October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE Temperature Distribution in Outer Divertor PFC Channel Assuming MHD-Laminarized LiPb Flow 2-D Moving Coordinate Analysis Inlet temperature = 653°C W thickness = 3 mm SiC f / SiC Thickness = 0.5 mm Pb-17Li Channel Thickness = 2 mm SiC f /SiC Inner Wall Thick. = 0.5 mm LiPb Velocity = 0.35 m/s Surface Heat Flux = 5 MW/m 2 Max. W Temp. = 1150°C Max. SiC f / SiC Temp. = 970°C

October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE Divertor Channel Geometry Optimized for Acceptable Stress and Pressure Drop 2-cm toroidal dimension and 2.5 mm minimum W thickness selected (+ 1mm sacrificial layer) SiC f /SiC thermal pressure stress ~ MPa  P minimized to ~0.55/0.7 MPa for lower/upper divertor Pressure Stress Thermal Stress

October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE Develop Plausible Fabrication Procedures 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

October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE 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.

October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE 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 TOFE

October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE Typical Blanket and Divertor Parameters for Design Point Blanket Outboard Region 1 No. of Segments32 No. of Modules per Segment6 Module Poloidal Dimension6.8 m Avg. Module Toroidal Dimen.0.19 m FW SiC/SiC Thickness 4 mm FW CVD SiC Thickness 1 mm FW Annular Channel Thickness4 mm Avg. LiPb Velocity in FW 4.2 m/s FW Channel Re3.9 x 10 5 FW Channel Transverse Ha4340 MHD Turbulent Transition Re2.2 x 10 6 FW MHD Pressure Drop 0.19 MPa Maximum SiC/SiC Temp.996°C Maximum CVD SiC Temp. (°C)1009 °C Max. LiPb/SiC Interface Temp. 994°C Avg. LiPb Vel. in Inner Channel 0.11 m/s Divertor Poloidal Dimension (Outer/Inner)1.5/1.0 m Divertor Channel Toroidal Pitch2.1 cm Divertor Channel Radial Dimension3.2 cm No. of Divertor Channels (Outer/Inner) 1316/1167 SiC/Si Plasma-Side Thickness 0.5 mm W Thickness 3.5 mm PFC Channel Thickness 2 mm Number of Toroidal Passes2 Outer Div. PFC Channel V (Lower/Upper) 0.35/0.42 m/s LiPb Inlet Temperature (Outer/Inner) 653/719 °C Pressure Drop (Lower/Upper) 0.55/0.7 MPa Max. SiC/SiC Temp. (Lower/Upper) 970/950°C Maximum W Temp. (Lower/Upper) 1145/1125°C W Pressure + Thermal Stress ~35+50 MPa SiC/SiC Pressure + Thermal Stress ~ MPa Toroidal Dimension of Inlet and Outlet Slot1 mm Vel. in Inlet & Outlet Slot to PFC Channel m/s Interaction Parameter in Inlet/Outlet Slot

October 16-19, 2000 A. R. Raffray, et al., ARIES-AT Blanket and Divertor, ANS Top. Meet. On TOFE Conclusions ARIES-AT Blanket and Divertor Design Based on High-Temperature Pb-17Li as Breeder and Coolant and SiC f /SiC Composite as Structural Material –High performance –Attractive safety features –Simple design geometry –Reasonable design margins as an indication of reliability –Credible maintenance and fabrication processes Key R&D Issues –SiC f /SiC fabrication/joining, and material properties at high temperature and under irradiation including: Thermal conductivity, maximum temperature, lifetime – MHD effects in particular for the divertor