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

Benefits of Radial Build Minimization and Requirements Imposed on ARIES Compact Stellarator Design Benefits of Radial Build Minimization and Requirements Imposed on ARIES Compact Stellarator Design

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

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• 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.

Objectives

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• 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 – Blanket & shield protect VV – Blanket, shield & VV protect magnets

• 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?

Background

Vacuum Vessel Shield FW / Blanket Magnet

Permanent Components

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New Approach for Blanket & Shield Arrangement

WC-Shield

Blanket Magnet Plasma

Dmin

Shield/VV

Xn through nominal blanket & shield Xn at Dmin

(magnet moves closer to plasma)

Plasma Shield/VV Blanket Magnet

3 FP Configuration

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Shield-only Zone Covers ~8% of FW Area

Beginning

• f Field

Period Middle

• f Field

Period

3 FP Configuration

f = 0 f = 60

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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

Breeding Blanket Concepts

_________________________ * With or without SiC inserts.

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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):

Fast n fluence to Nb3Sn (En > 0.1 MeV) 1019 n/cm2 Nuclear heating 5 mW/cm3 Dose to polyimide insulator 1011 rads dpa to Cu stabilizer 6x10-3 dpa

Machine Lifetime

40 FPY

Availability

85%

Radial Builds have been Defined Using Same Design Criteria

___________ * 4.5 MW/m2 for solid breeder concept.

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• 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.

Breeding Performance

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 10 20 30 40 50 60 70 Local TBR FW/Blanket Thickness (cm)

Flibe LiPb/SiC LiPb/FS Li/FS Flibe LiPb/SiC LiPb/FS Li/FS SB SB

Thick blanket; no structure; no multiplier Actual Design

0.8 1.0 1.2 1.4 1.6 1.8 2.0 1.1 1.2 1.3 Tritium Breeding Ratio Neutron Energy Multiplication

Li4SiO4 Li Li2O FLiBe Li2TiO3 Li17Pb83- nat Li2ZrO3 LiAlO2 Li17Pb83- 90%Li6

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Representative Radial Build

(LiPb/FS/He System; Internal VV)

SOL

Vacuum Vessel FS Shield

Gap

Thickness (cm)

FW

Gap + Th. Insulator

Winding Pack

Plasma

5 4.8 2 ≥ 2 32 31 2.2 28

D ≥ 149 cm | |

SOL

Vacuum Vessel

Back Wall Gap

Thickness (cm)

Gap + Th. Insulator Coil Case & Insulator

Winding Pack

Plasma

5 2 2 47 31 2.2 28

| |

Coil Case & Insulator

Dmin = 118 cm Shield Only Zones @ Dmin

Blanket (LiPb/FS/He) 47 11 WC Shield

Blanket & Shield Zones

Back Wall

9 1

G a p FW

4.8

External Structure External Structure

18 18

B l a n k e t

Magnet P l a s m a

Dmin

Shield/VV

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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.

Nominal Radial Standoff Varies Widely with Blanket Concept

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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 – –

Dmin Varies within 20 cm with blanket Concept

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Comparison Between Radial Builds

• 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).

50 100 150 200 Plasma to Mid-coil Distance (cm)

Flibe/FS LiPb/SiC LiPb/FS SB/FS Li/FS Li/V SPPS

SPPS

50 100 150 200 Minimum Plasma to Mid-coil Distance (cm)

Flibe/FS LiPb/SiC LiPb/FS SB/FS Li/FS Li/V SPPS

SPPS

Nominal Blanket/Shield Shield-only Zones

Helium Helium

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• 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.

New Shielding Approach Introduces Design Issues

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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

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Well Optimized Radial Build Contributed to Compactness of ARIES-CS

UWTOR-M 24 m

5 10 15 20 25 2 4 6 8 m

Average Major Radius (m)

ASRA-6C 20 m HSR-G 18 m SPPS 14 m FFHR-J 10 m ARIES-CS ARIES-ST Spherical Torus 3.2 m ARIES-AT Tokamak 5.2 m

Stellarators | |

2 FP 7.5 m 3 FP 8.25 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.

1982 1987 2000 1996 2000 2004

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• 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.

Conclusions

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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

Companion Presentations

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Magnet Design

Plasma/Blanket/Shield/VV

Insulator - 0.2 cm Winding Pack-I - 17 cm Winding Pack-II - 14 cm Insulator - 0.2 cm External Structure - 18 cm Magnet Homogeneous Composition: 45% 316-SS (gray) 50% winding packs (orange/black) 5% GFF polyimide (white) MT Winding Pack-I: 12.7% MgB2 45.5% Cu 15.5% He @ 15 k 17.3% 316-SS 9.0% GFF poly. LT Winding Pack-II: 9.6% NbTi 54.1% Cu 21.8% LHe @ 4 k 5.5% 316-SS 9.0% GFF poly.

MT WP-I @ 15 K LT WP-II @ 4 K

Coil Case - 2 cm

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3 FP Configuration R = 8.25 m a = 1.85 m 2 FP Configuration R = 7.5 m a = 2 m

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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

LiPb/FS/He Composition

_________ # Without SiC inserts. * FS and He contents will be adjusted later.