July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 1 ARIES-AT Blanket and Divertor Design Presented by A. R. Raffray 1 Contributors: 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 Meeting on Fusion Blanket Designs using SiC f /SiC as Structural Material SNECMA, Bordeaux July 4, 2001

A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 2 Presentation Highlights How Design Was Developed to Meet Overall Objective Outline Power Cycle Material ARIES-AT Reactor Coolant Routing Blanket Design and Analysis Divertor Design and Analysis Fabrication Maintenance Manifolding Analysis 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

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 3 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 Advanced Brayton Cycle Parameters Based on Present or Near Term Technology Evolved with Expert Input from General Atomics * 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 * 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

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 4 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 Design Point: Max. cycle He temp. = 1050°C Total compression ratio = 3 Cycle efficiency = Cycle He temp. at HX inlet = 604°C Pb-17 Inlet temp. to power core = 650°C

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 5 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,” to appear in Fusion Engineering & Design, 2001 * From ARIES-I

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 6 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

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 7 Cross-Section and Plan View (1/6 sector) of ARIES-AT Showing Power Core Components

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 8 Coolant Routing Through 5 Circuits Serviced by Annular Ring Header (I) LiPb Coolant Inlet Temperature654°C Outlet Temperature1100°C Blanket Inlet Pressure 1 MPa Divertor Inlet Pressure1.8 MPa Mass Flow Rate 22,700 kg/s Circuit 1 - Lower Divertor + IB Blkt Region Thermal Power and Mass Flow Rate: 501 MW and 6100 kg/s Circuit 2 - Upper Divertor + 1/2 OB Blanket I 598 MW and 7270 kg/s Circuit 3 - 1/2 OB Blanket I 450 MW and 5470 kg/s Circuit 4 - IB Hot Shield + 1/2 OB Blanket II 182 MW and 4270 kg/s Circuit 5 - OB Hot Shield + 1/2 OB Blanket II 140 MW and 1700 kg/s Circuit 1: Lower Divertor + IB Blanket

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 9 Coolant Routing Through 5 Circuits Serviced by Annular Ring Header (II) Circuit 2: Upper Divertor + 1/2 OB Blanket ICircuit 3: 1/2 OB Blanket I

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 10 Coolant Routing Through 5 Circuits Serviced by Annular Ring Header (III) Circuit 4: IB Hot Shield + 1/2 OB Blanket II Circuit 5: OB Hot Shield + 1/2 OB Blanket II

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 11 ARIES-AT Blanket Utilizes a 2-Pass Coolant Approach to Uncouple Structure Temperature from Outlet Coolant Temperature Maintain blanket SiC f /SiC temperature (~1000°C) < Pb-17Li outlet temperature (~1100°C) ARIES-AT Outboard Blanket Segment Configuration

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 12 Poloidal Distribution of Surface Heat Flux and Neutron Wall Load

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 13 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

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 14 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

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 15 Pressure Stress Analysis of Outer Shell of Blanket Module (Max.  = 85 MPa) Thermal Stress Distribution in Toroidal Half of Outboard Blanket Module (Max.  = 113 MPa) Detailed Stress Analysis of Blanket Module to Maintain Conservative Margins as Reliability Measure: Stress Analysis of Outboard Module 6 modules per outboard segment Side walls of all inner modules are pressure balanced except for outermodules 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 limit The maximum pressure stress + thermal stress at the first wall ~ MPa.

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 16 Pressure Stress Analysis of Inner Shell Shows Comfortable Stress Limit Margin The inner wall is designed to withstand the difference between blanket inlet and outlet pressures (~0.25 MPa). The thickness of the upper and lower wall is 5 mm. The maximum stress is 116 MPa for a side-wall thickness of 8 mm (<<190 MPa limit) In addition, the maximum pressure differential of ~0.25 MPa occurs at the lower poloidal location. The inner wall thickness could be tapered down to ~5 mm at the upper poloidal location if needed to minimize the SiC volume fraction.

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 17 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) Outboard Divertor Plate Outlet Pb-17LiManifold Inlet Pb-17LiManifold Tungsten Armor SiC f /SiC Poloidal Channels

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 18 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

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 19 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

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 20 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

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 21 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; Develop Plausible Fabrication Procedures and Minimize Joints in High Irradiation Region Brazing procedure selected for reliable joint contact area

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 22 ARIES-AT First Outboard Region Blanket: Proposed 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.

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 23 Proposed Fabrication Procedure of ARIES-AT Divertor Plate 1.Manufacture individual rectangular divertor tubes by SiC f weaving and SiC Chemical Vapor Infiltration (CVI) or polymer process, including grooves for inner”T” coolant guide; 2.Manufacture inner”T” coolant guide by SiC f weaving and SiC Chemical Vapor Infiltration (CVI) or polymer process (leave inlet feeding holes or machine them afterwards) 3.Slide inner”T” flow separator in each channel along grooves; 4.Braze the all channels together forming divertor plate;

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 24 Proposed Fabrication Procedure of ARIES-AT Divertor Plate (cont.) 5.Braze end caps and manifolds at each end of divertor; 6.Coat 3-mm W layer on plasma facing side (e.g. by vapor deposition followed by brazing) Outlet Pb-17LiManifold Inlet Pb-17LiManifold Tungsten Armor SiC f /SiC Poloidal Channels

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 25 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 All Lifetime Components Except for: Divertor, IB Blanket, and OB Blanket I

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 26 Manifolding Analysis Annular manifold configuration with low temperature inlet Pb-17Li in outer channel and high temperature outlet Pb-17Li in inner channel Pb-17Li Inlet Pb-17Li Outlet r i r o q'' Can the manifold be designed to maintain Pb-17Li /SiC T interface < Pb-17Li T outlet while maintaining reasonable  P? Use manifold between ring header and outboard blanket I as example

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 27 Pb-17Li/SiC T interface, Pb-17Li  T Bulk due to Heat Transfer in SiC f /SiC Annular Piping, and  P as a Function of Inner Channel Radius 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 minimize  T bulk while maintaining a reasonable  P

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 28 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 ~30+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

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 29 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 (void swelling and Pb-17Li compatibility), lifetime – MHD effects in particular for the divertor – Pb-17Li properties at high temperature

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 30 For More Information and Documentation on ARIES-AT and Other ARIES Studies Please see the ARIES web site:

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 31 Alternative Option for Fabricating and Brazing ARIES-AT Blanket Segment E.g. First Outboard Region Blanket Segment 1.Manufacture separate poloidal 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.Insert free-floating inner shell between two outer shell halves; 4.Braze the two half outer shells together with the braze junction toward the back of the segment to minimize neutron fluence effects; 5.As before…. If it is not possible to fabricate SiC f /SiC in tubular form: AA Section A-A