Summary of Major Features of ARIES- ST and ARIES-AT Blanket Designs

Transcription

1 Summary of Major Features of ARIES- ST and ARIES-AT Blanket Designs Presented by A. René Raffray University of California, San Diego with the Contribution of the ARIES Team and S. Malang APEX Meeting, SNL, Albuquerque For more information see:

2 Unique Features of ARIES-ST Power Plant Include: Use of water coolant in the power core (for the Cu centerpost) strongly discourages the use of reactive materials such as Li and Be High power cycle η is needed to offset the effect of high recirculating power in the normal-conducting TF system Relatively high power density results from very high plasma beta The absence of space on the inboard side for a breeding blanket places additional constraints on material selection and dimensions The highly elongated plasma together with an integrated outboard TF shell and vacuum vessel led to a vertical maintenance scheme and toroidally integrated blanket

3 ARIES-ST Power Parameters Fusion Power Neutron Power Alpha Power Total Thermal Power 2859 MW 2287 MW 572 MW 3107 MW Ave. FW Surf. Heat Flux 0.46 MW/m 2 Max. FW Surf. Heat 0.6 MW/m 2 Average Wall Load 4.2 MW/m 2 Maximum ØB Wall Load 6.0 MW/m 2

4 ARIES-ST Utilizes a Dual Coolant Approach to Uncouple Structure Temperature from Main Coolant Temperature Breeder Unit Cell He-cooled Ferritic Steel 10 Ferritic steel+pb-17li+he Flow lower temperature He ( C) to cool structure and higher temperature Pb-17Li ( C) for flow through blanket 232 SiC Pb 83 Li Steel He SiC PbLi Total Area (cm 2 ) Volume Fraction (%)

5 ARIES-ST Blanket Configuration

6 Example Analysis of ARIES-ST First Wall Parameters Used in the Analysis First wall thickness 3 mm Second wall thickness 3 mm Web thickness 4 mm First wall channel depth 25 mm Roughness of ribbed surface 45 µm Roughness of smooth surfaces 1.5 µm Coolant pressure 12 MPa Coolant velocity 75 m/s Steel properties: Thermal conductivity 26.2 W/m-K Young s modulus 207 GPa Poisson s ratio 0.3 Thermal expansion coeff. 12x 10-6 /K First Wall Temperature Distribution

7 Thorough Stress Analysis Confirms Stresses are Within Allowable Values Design condition temperature calculated code limit peak value membrane stress (in web) 500 C 68 MPa 183 MPa (S mt ) membrane plus bending 580 C 148 MPa 195 MPa (1.5 S mt ) primary plus secondary 575 C 430 MPa 464 MPa (3 S m ) First Wall Thermal + Pressure Von Mises Stress

8 ARIES-ST Power Core Coolant Routing (Driving a Brayton Power Cycle) Cycle He used to cool divertor and FW High temperature Pb-17Li from blanket used to heat He through IHX Power Core He temp C He pressure 12 MPa Pb-17Li temperature C He flow rate 1444 kg/s Pb-17Li flow rate kg/s He temperature to turbine C Power cycle η > 45% Temperature, C FW Grid plates Divertor IB shield IB FW and W shells PbLi Helium to turbine 400 Helium in power core Helium in HX Percent of Heat Transferre

9 ARIES-AT Blanket Design Objective Develop ARIES-AT Blanket Design 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

10 Brayton Cycle Offers Best Near-Term Possibility of Power Conversion with High Efficiency Maximize potential gain from hightemperature operation with SiC f /SiC Compatible with liquid metal blanket through use of IHX High efficiency translates in lower COE and lower heat load

11 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 intercoolers Turbine efficiency = 0.93 Compressor efficiency = 0.88 Recuperator effectiveness (advanced design) = 0.96 Cycle He fractional ΔP = 0.03 Intermediate Heat Exchanger - Effectiveness = (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," presented at the 14th ANS Topical Meeting on Technology of Fusion Energy, October 15-19, 2000, Park City Utah

12 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 = Cycle He temp. at HX inlet = 604 C Pb-17 Inlet Temp. to Power Core = 650 C

13 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 Factor 0.95 Young's Modulus GPa Poisson's ratio Thermal Expansion Coefficient 4 ppm/ C Thermal Conductivity in Plane 20 W/m-K Thermal Conductivity through Thickness 20 W/m-K Maximum Allowable Combined Stress 190 MPa Maximum Allowable Operating Temperature 1000 C Maximum Allowable SiC/LiPb Interface Temperature 1000 C Maximum Allowable SiC Burnup 3% 4 1 D. Henderson, et al, and the ARIES Team, Activation, Decay Heat, and Waste Disposal Analyses for ARIES-AT Power Plant," 14th TOFE 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

14 ARIES-AT Machine and Power Parameters 1,2 Power and Neutronics Parameters Fusion 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/m 2 Max. FW Surf. Heat 0.34 MW/m 2 Average Wall Load 3.2 MW/m 2 Maximum ØB Wall Load 4.8 MW/m 2 Maximum I/B Wall Load 3.1 MW/m 2 Machine Geometry Major Radius Minor Radius FW Location at ØB Midplane FW Location at Lower ØB I/B FW Location Toroidal Magnetic Field On-axis Magnetic Field Magnetic Field at I/B FW Magnetic Field at ØB FW 5.2 m 1.3 m 6.5 m 4.9 m 3.9 m 5.9 T 7.9 T 4.7 T 1 F. Najmabadi, et al.and the ARIES Team, Impact of Advanced Technologies on Fusion Power Plant Characteristics, 14th ANS Top. Meeting.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

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

16 Coolant Routing Through 5 Circuits Serviced by Annular Ring Header Pb-17Li Coolant Inlet Temperature 653 C Outlet Temperature 1100 C Blanket Inlet Pressure 1 MPa Divertor Inlet Pressure 1.7 MPa Mass Flow Rate 22,700 kg/s 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

17 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)

18 ARIES-AT Outboard Blanket Segment Configuration

19 Multi-Dimensional Neutronics Analysis to Calculate Tritium Breeding Ratio and Heat Generation Profiles 1 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 1 L. A. El-Guebaly and the ARIES Team, Nuclear Performance Assessment for ARIES-AT Power Plant, 14th TOFE

20 Poloidal Distribution of Surface Heat Flux and Neutron Wall Load

21 Moving Coordinate Analysis to Obtain Pb-17Li Temperature Distribution in ARIES-AT First Wall Channel and Inner Channel Assume MHD-flowlaminarization 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 First Wall Channel q'' plasma Poloidal Radial SiC /SiC First Wall v FW q'' back v back Pb-17L Inner Channel q''' LiPb Out SiC /SiC Inner Wall

22 Temperature Distribution in ARIES-AT Blanket Based on Moving Coordinate Analysis Pb-17Li Outlet Temp. = 1100 C Max. SiC/PbLi Interf. Temp. = 994 C Pb-17Li Inlet Temp. = 764 C Pb-17Li Inlet Temp. = 764 C Pb-17Li Outlet Temp. = 1100 C FW Max. CVD and SiC/SiC Temp. = 1009 C and 996 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

23 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: MPa for 5-mm thickness 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)

24 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.

25 3-D Thermal Stress Analysis of Toroidal Half of Module in First Outboard Blanket Region Example case: Effective 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)

26 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 freefloating 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 Butt joint Lap joint Double lap joint Mortise and tenon joint Tapered butt joint Tapered lap joint

27 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.

28 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

29 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 ΔT bulk while maintaining a reasonable ΔP Temp. ( C) Max. LiPb/SiC T int k SiC (W/m-K) Circuit 2: Series Flow through Upper Divertor and One O/B Blanket Region 1 Segment One of 16 Annular Pipes LiPb Mass Flow Rate in Annular Piping = 45.4 k Piping Length = 8 m Outer Radius, o = r SiC/SiC Outer and Inner Wall Thickness = 5 mm LiPb Inlet Temperature = 653 C LiPb Outlet Temperature = 1100 C LiPb!T bulk due to q'' Annular Piping Inner Channel Radius, i (m) r 1 10!P (MPa) LiPb Inlet LiPb Outlet r i r o q'' Annular Piping Inner Channel Radius, i (m) r

30 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 SiC f /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 10 5 First Wall Channel Transverse Ha 4340 MHD Turbulent Transition Re 2.2 x 10 6 First Wall MHD Pressure Drop 0.19 MPa Maximum SiC f /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

31 ARIES-AT Blanket Design - Conclusions The Blanket Design Utilizes High-Temperature Pb-17Li as Breeder and Coolant and SiC f /SiC Composite as Structural Material High performance (Brayton cycle efficiency ~59%) Attractive safety features (low activation SiC f /SiC) Simple design geometry Reasonable design margins as an indication of reliability Credible maintenance and fabrication processes Key R&D Issues Have Been Identified, Including SiC f /SiC fabrication/joining, and material properties at high temperature and under irradiation, in particular: Thermal conductivity, maximum temperature limits, lifetime