Benefits of Radial Build Benefits of Radial Build Minimization and - PowerPoint PPT Presentation

Benefits of Radial Build Benefits of Radial Build Minimization and Requirements Minimization and Requirements Imposed on ARIES Compact Imposed on ARIES Compact Stellarator Design Stellarator Design Laila El-Guebaly (UW), R. Raffray (UCSD), S. Malang (Germany), J. Lyon (ORNL), L.P. Ku (PPPL) and the ARIES Team 16 th 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 B max fi smaller machine and lower cost. Vacuum Vessel • All components provide shielding function: FW / Blanket Magnet Shield – Blanket protects shield – Blanket & shield protect VV – Blanket, shield & VV protect magnets Permanent Components • Blanket offers less shielding performance than shield. • Could design tolerate shield-only at D min (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 3 FP Plasma Blanket Plasma Configuration D min WC-Shield Magnet Xn at D min Xn through nominal (magnet moves closer to plasma) blanket & shield 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 H 2 O LiPb – SiC LiPb LiPb H 2 O LiPb * – FS He/LiPb He H 2 O Li 4 SiO 4 Be FS He He H 2 O External VV: LiPb * – FS He/LiPb He or H 2 O 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/m 2 Overall TBR 1.1 (for T self-sufficiency) Damage Structure 200 dpa - advanced FS 3% burn up - SiC (for structural integrity) Helium Production @ VV 1 appm (for reweldability of FS) HT S/C Magnet (@ 15 K): 10 19 n/cm 2 Fast n fluence to Nb 3 Sn (E n > 0.1 MeV) mW/cm 3 Nuclear heating 5 Dose to polyimide insulator 10 11 rads 6x10 -3 dpa dpa to Cu stabilizer Machine Lifetime 40 FPY Availability 85% ___________ * 4.5 MW/m 2 for solid breeder concept. 7

Breeding Performance Actual Design Thick blanket; no structure; no multiplier 2.0 1.4 Li 1.2 Tritium Breeding Ratio 1.8 Li/FS Li 17 Pb 83 - 90%Li6 SB 1.0 LiPb/FS 1.6 Local TBR Li 17 Pb 83 - nat 0.8 Flibe 1.4 Li 2 O 0.6 FLiBe 1.2 LiPb/SiC 0.4 Li 2 TiO 3 Li 4 SiO 4 LiPb/FS 1.0 Flibe 0.2 Li 2 ZrO 3 SB Li/FS LiAlO 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

& Shield Blanket Zones D min Shield/VV Magnet P l a s m a B l n a k e t Plasma | SOL 5 4.8 FW Representative Radial Build Plasma Blanket (LiPb/FS/He System; Internal VV) 47 (LiPb/FS/He) | SOL 5 4.8 FW Back Wall 9 1 a p G D ≥ 149 cm 47 WC Shield 9 FS Shield D min = 118 cm 32 11 Back Wall Gap 2 Gap 2 Vacuum Vessel 28 28 Vacuum Vessel ≥ 2 Gap + Th. Insulator Gap + Th. Insulator 2 2.2 2.2 Coil Case & Insulator Coil Case & Insulator 31 31 Winding Pack Winding Pack | | 18 18 External Structure External Structure Thickness @ D min Thickness Shield Zones Only (cm) (cm)

Nominal Radial Standoff Varies Widely with Blanket Concept D (m) ARIES-CS : Blanket/Shield/VV/Gaps Plasma – Mid Coil Internal VV: Flibe/FS/Be 1.07 (min) 1.32 (min) LiPb/SiC 1.15 1.40 LiPb/FS/He 1.24 1.49 Li 4 SiO 4 /Be/FS/He 1.30 (max) 1.55 (max) Blanket/Shield/Gaps External VV: 1.22 LiPb/FS/He/H 2 O 1.47 LiPb/FS/He 1.60 1.85 Li/FS/He 1.79 (max) 2.04 (max) SPPS * : External VV: 1.96 Li/V 1.20 –––––––––––––––––––––––– * 15 cm SOL, 36 cm half winding pack, 15 cm thick cryostat, and 8 cm wide shield-magnet gap. 10

D min Varies within 20 cm with blanket Concept D min (m) ARIES-CS : WC-Shield/VV Plasma – Mid Coil Internal VV: Flibe/FS/Be 0.86 (min) 1.11 (min) LiPb/SiC 0.89 1.14 LiPb/FS/He 0.93 1.18 Li 4 SiO 4 /Be/FS/He 1.04 (max) 1.29 (max) WC-Shield External VV: LiPb/FS/He/H 2 O 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 Minimum Plasma to Mid-coil Distance (cm) SPPS SPPS Plasma to Mid-coil Distance (cm) 150 150 100 100 50 50 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 B max – 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 D min 1.11 1.14 1.18 1.29 1.16 Overall TBR 1.1 1.1 1.1 1.1 1.1 Energy Multiplication (M n ) 1.2 1.1 1.15 1.3 1.13 Thermal Efficiency ( h th ) ~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 D min , M n , and h th 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 2000 1987 1996 1982 4 ARIES-CS ARIES-AT Tokamak 3 FP 2 FP ASRA-6C HSR-G 5.2 m 8.25 m 7.5 m SPPS UWTOR-M 2 20 m FFHR-J 18 m 14 m 24 m 10 m 10 15 20 25 5 0 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 MT WP-I @ 15 K Winding Pack-I - 17 cm LT WP-II @ 4 K Winding Pack-II - 14 cm Insulator - 0.2 cm External Structure - 18 cm MT Winding Pack-I: LT Winding Pack-II: Magnet Homogeneous Composition: 12.7% MgB 2 9.6% NbTi 45% 316-SS (gray) 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

2 FP Configuration 3 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