BBenenefitsefits ooff RRadadialial BBuuildild MinMinimimizatioizationn anandd RReqequuirirememenentsts ImImposedposed onon AARRIEIESS CComompapacctt SStetellallararatotorr DDeesigsignn Laila El-Guebaly (UW), R. Raffray (UCSD), S. Malang (Germany), J. Lyon (ORNL), L.P. Ku (PPPL) and the ARIES Team 16th TOFE Meeting September 14 - 16, 2004 Madison, WI Objectives • Define radial builds for proposed blanket concepts. • Propose innovative shielding approach that minimizes radial standoff. • Assess implications of new approach on: – Radial build – Tritium breeding – Machine size – Complexity – Safety – Economics. 2 Background • Minimum radial standoff controls COE, unique feature for stellarators. • Compact radial build means smaller R and lower Bmax fi smaller machine and lower cost. • All components provide shielding function: – Blanket protects shield Magnet Shield FW / Blanket – Blanket & shield protect VV Vessel Vacuum – Blanket, shield & VV protect magnets Permanent Components • Blanket offers less shielding performance than shield. • Could design tolerate shield-only at Dmin (no blanket)? • What would be the impact on T breeding, overall size, and economics? 3 New Approach for Blanket & Shield Arrangement Magnet Shield/VV Shield/VV Blanket Plasma Blanket Plasma 3 FP Configuration WC-Shield Dmin Magnet Xn through nominal Xn at Dmin blanket & shield (magnet moves closer to plasma) 4 Shield-only Zone Covers ~8% of FW Area 3 FP Configuration Beginning of Field Period f = 0 f = 60 Middle of Field Period 5 Breeding Blanket Concepts Breeder Multiplier Structure FW/Blanket Shield VV Coolant Coolant Coolant ARIES-CS: Internal VV: Flibe Be FS Flibe Flibe H2O LiPb – SiC LiPb LiPb H2O * LiPb – FS He/LiPb He H2O Li4SiO4 Be FS He He H2O External VV: * LiPb – FS He/LiPb He or H2O He Li – FS He/Li He He SPPS: External VV: Li – V Li Li He _________________________ * With or without SiC inserts. 6 Radial Builds have been Defined Using Same Design Criteria Peak n Wall Loading 3* MW/m2 Overall TBR 1.1 (for T self-sufficiency) Damage Structure 200 dpa - advanced FS (for structural integrity) 3% burn up - SiC Helium Production @ VV 1 appm (for reweldability of FS) HT S/C Magnet (@ 15 K): 19 2 Fast n fluence to Nb3Sn (En > 0.1 MeV) 10 n/cm Nuclear heating 5 mW/cm3 Dose to polyimide insulator 1011 rads dpa to Cu stabilizer 6x10-3 dpa Machine Lifetime 40 FPY Availability 85% ___________ * 4.5 MW/m2 for solid breeder concept. 7 Breeding Performance Thick blanket; no structure; no multiplier Actual Design 2.0 1.4 1.8 Li 1.2 Li Pb - 90%Li6 Li/FS 17 83 1.0 SB 1.6 LiPb/FS Li Pb - nat 17 83 0.8 Flibe Li O 1.4 2 0.6 FLiBe Breeding Ratio 1.2 Local TBR LiPb/SiC Li TiO 0.4 2 3 Li SiO LiPb/FS 1.0 4 4 Flibe Li ZrO 0.2 Tritium LiAlO 2 3 SB Li/FS 2 LiPb/SiC 0.8 0.0 1.1 1.2 1.3 0 10 20 30 40 50 60 70 Neutron Energy Multiplication FW/Blanket Thickness (cm) • Local TBR approaches 1.25. • Blankets sized to provide 1.1 overall TBR based on 1-D analysis combined with blanket coverage fraction. • 3-D analysis should confirm key parameters. 8 Representative Radial Build (LiPb/FS/He System; Internal VV) 5 1 32 2 28 ≥ 2 2.2 31 18 Thickness 4.8 47 9 (cm) Blanket Insulator Insulator Wall & Shield Structure & & FW /FS/He) Gap Gap SOL Plasma Th. Blanket + FS Shield Zones Back Case Case LiPb Winding Pack Winding ( Vacuum Vessel Vacuum External Gap Coil Coil | D ≥ 149 cm | 5 Thickness 4.8 47 11 2 28 2 2.2 31 18 Magnet (cm) Shield/VV Shield all Blanket Insulator Plasma W Insulator Structure FW & & SOL Only Gap Plasma Th. C Shield Back ase ase Dmin + Zones C W Winding Pack Winding Vacuum Vessel Vacuum oil oil External Gap @ D C min | Dmin = 118 cm | 9 Nominal Radial Standoff Varies Widely with Blanket Concept D (m) ARIES-CS: Internal VV: Blanket/Shield/VV/Gaps Plasma – Mid Coil Flibe/FS/Be 1.07 (min) 1.32 (min) LiPb/SiC 1.15 1.40 LiPb/FS/He 1.24 1.49 Li4SiO4/Be/FS/He 1.30 (max) 1.55 (max) External VV: Blanket/Shield/Gaps LiPb/FS/He/H2O 1.22 1.47 LiPb/FS/He 1.60 1.85 Li/FS/He 1.79 (max) 2.04 (max) SPPS*: External VV: Li/V 1.20 1.96 –––––––––––––––––––––––– * 15 cm SOL, 36 cm half winding pack, 15 cm thick cryostat, and 8 cm wide shield-magnet gap. 10 Dmin Varies within 20 cm with blanket Concept Dmin (m) ARIES-CS: Internal VV: WC-Shield/VV Plasma – Mid Coil Flibe/FS/Be 0.86 (min) 1.11 (min) LiPb/SiC 0.89 1.14 LiPb/FS/He 0.93 1.18 Li4SiO4/Be/FS/He 1.04 (max) 1.29 (max) External VV: WC-Shield LiPb/FS/He/H2O 0.95 1.20 LiPb/FS/He 0.93 1.18 Li/FS/He 0.91 1.16 SPPS: External VV: Li/V – – 11 Comparison Between Radial Builds 200 200 Nominal Blanket/Shield Shield-only Zones SPPS SPPS ) 150 150 id-coil Distance (cm) 100 100 a to Mid-coil Distance (cm 50 50 Plasm inimum Plasma to M M 0 0 Li/V Li/V Flibe/FS LiPb/SiC LiPb/FS SB/FS Li/FS Flibe/FS LiPb/SiC LiPb/FS SB/FS Li/FS SPPS SPPS Helium Helium • Flibe system offers most compact radial build, but Be raises safety and economic concerns. • He coolant occupies 10-30 cm of radial standoff. • Water is effective shielding material for VV fi avoid breeders incompatible with water (such as Li). 12 New Shielding Approach Introduces Design Issues • Benefits: – Compact radial standoff – Small R and low Bmax – Low COE. • Challenges (to be addressed in Phase II of study): – Integration of shield-only zones with surrounding blanket. – Incorporation of decay heat removal loop for WC-shield. – Handling of massive WC-shield during maintenance. 13 Key Parameters for System Analysis Flibe/FS/Be LiPb/SiC LiPb/FS SB/FS/Be Li/FS Dmin 1.11 1.14 1.18 1.29 1.16 Overall TBR 1.1 1.1 1.1 1.1 1.1 Energy Multiplication (Mn) 1.2 1.1 1.15 1.3 1.13 Thermal Efficiency (hth) ~45% 55-60% ~45% ~45% ~45% FW Lifetime (FPY) 6.5 6 5 4.4 7 System Availability ~85% ~85% ~85% ~85% ~85% Integrated system analysis will assess impact of Dmin, Mn, and hth on COE 14 Well Optimized Radial Build Contributed to Compactness of ARIES-CS m ARIES-ST Spherical Torus 8 3.2 m Stellarators 6 | | 2004 2000 1996 2000 1987 1982 4 ARIES-AT ARIES-CS Tokamak 2 FP 3 FP HSR-G ASRA-6C 5.2 m 7.5 m 8.25 m SPPS 2 FFHR-J 18 m 20 m UWTOR-M 10 m 14 m 24 m 0 5 10 15 20 25 Average Major Radius (m) Major radius more than halved by advanced physics and technology, dropping from 24 m for UWTOR-M to 7-8 m for ARIES-CS and approaching R of advanced tokamaks. 15 Conclusions • Innovative shielding approach has been developed for ARIES-CS. • Combination of shield-only zones and non-uniform blanket represents best option for ARIES-CS. • Solutions for challenges facing proposed shielding approach will be developed in Phase-II of study. • Means of dimension control along with advances in physics and technology helped ARIES-CS achieve the compactness that other stellarators had not been able to achieve before. • Positive trends in physics and engineering position compact stellarators for bright future. 16 Companion Presentations Poster on Wednesday @ 1:30 - 3:30 PM: Initial Activation Assessment for ARIES Compact Stellarator Power Plant L. El-Guebaly, P. Wilson, D. Paige and the ARIES Team Oral on Tuesday @ 10:30 - 12 AM: Evolution of Clearance Standards and Implications for Radwaste Management of Fusion Power Plants L. El-Guebaly, P. Wilson, D. Paige and the ARIES Team 17 Magnet Design Plasma/Blanket/Shield/VV Coil Case - 2 cm Insulator - 0.2 cm Winding Pack-I - 17 cm MT WP-I @ 15 K Winding Pack-II - 14 cm LT WP-II @ 4 K Insulator - 0.2 cm External Structure - 18 cm MT Winding Pack-I: LT Winding Pack-II: Magnet Homogeneous Composition: 12.7% MgB 9.6% NbTi 45% 316-SS (gray) 2 45.5% Cu 54.1% Cu 50% winding packs (orange/black) 15.5% He @ 15 k 21.8% LHe @ 4 k 5% GFF polyimide (white) 17.3% 316-SS 5.5% 316-SS 9.0% GFF poly. 9.0% GFF poly. 18 3 FP Configuration 2 FP Configuration R = 8.25 m R = 7.5 m a = 1.85 m a = 2 m 19 LiPb/FS/He Composition Component Composition FW 31% FS Structure 69% He Coolant Blanket# 90% LiPb with 90% enriched Li 3% FS Structure 7% He Coolant Back Wall 80% FS Structure 20% He Coolant WC Shield* 90% WC Filler 3% FS Structure 7% He Coolant FS Shield 15% FS Structure 10% He Coolant 75% Borated Steel Filler VV 28% FS Structure 49% Water 23% Borated Steel Filler _________ # Without SiC inserts. * FS and He contents will be adjusted later. 20.