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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