Initial Activation Assessment for ARIES Compact Stellarator

Power Plant

L. El-Guebaly, P. Wilson, D. Paige and the ARIES Team

Fusion Technology InstituteUniversity of Wisconsin - Madison

16th TOFE MeetingSeptember 14-16, 2004

Madison, WI

• Perform systematic activation assessment for interim ARIES-CS design.

• Evaluate:– Activity– Decay Heat

• Address waste-related issues:– Waste Disposal Rating– Breakdown of Class A and Class C waste– Any cleared materials?

Objectives

Breeder Multiplier Structure FW/Blanket Shield VVCoolant Coolant Coolant

Internal VV:Flibe Be FS Flibe Flibe H2O

LiPb – SiC LiPb LiPb H2O

LiPb – FS He/LiPb He H2O

External VV:LiPb – FS He/LiPb He/B-H2O He

LiPb – FS He/LiPb He He

Li – FS He/Li He He

SiC- and FS-Based Systems Selected for Initial Activation Analysis

Analysis Performed at Two Radial Cross Sections

Blanket

Magnet

Plasma

Shield/VV

Xn through nominal blanket/shield/VV

Xn through WC-Shield @ min

ARIES Compact Stellarator3 Field Period Configuration

LiPb/SiC Radial Build

SOL

Gap

Vac

uum

Ves

sel

FS S

hiel

d

Ga p

Thickness(cm)

FW /

Bla

n ke t

- I(L

iPb /

SiC

)

Gap

+ T

h. In

sula

tor

Win

ding

Pac

k

Plas

ma

5 1 2 ≥ 237 312.225 25

≥ 140 cm| |

SOL

Gap

Vac

uum

Ves

sel

WC

Shi

eld

Ga p

Thickness(cm)

WC

Shi

eld

Gap

+ T

h. In

sula

tor

Coi

l Cas

e &

Insu

lato

r

Win

ding

Pac

k

Plas

ma

5 1 2 225 312.225 25

| |C

oil C

ase

& In

sula

tor

min = 114 cm

ShieldOnlyZones

Bla

nket

-II

(LiP

b/Si

C)

25

11W

C S

hiel

d

BlanketZones

Ext

erna

l Str

uctu

reE

xter

nal S

truc

ture

18

18

LiPb/FS/He Radial Build

SOL

Vac

uum

Ves

sel

FS S

hiel

d

Ga p

Thickness(cm)

FW

Gap

+ T

h. In

sula

tor

Win

ding

Pac

k

Plas

ma

54.8 2 ≥ 232 202.228

≥ 149 cm| |

SOL

Vac

uum

Ves

sel

Bac

k W

all

Ga p

Thickness(cm)

Gap

+ T

h. In

sula

tor

Coi

l Cas

e &

Insu

lato

r

Win

ding

Pac

k

Plas

ma

52 247 202.228

| |C

oil C

ase

& In

sula

tor

min = 118 cm

ShieldOnlyZones

Bla

nket

(LiP

b/FS

/He)

47

11W

C S

hiel

d

BlanketZones B

ack

Wal

l

9 1

Gap

FW

4.8

Ext

erna

l Str

uctu

reE

xter

nal S

truc

ture

18

18

Average Neutron Wall Loading 2 MW/m2

Replaceable Component Lifetime 6 FPY for SiC5 FPY for FS

Permanent Component Lifetime 40 FPY

System Availability 85%

Key Parameters for Activation Assessment

Activity

• At intermediate time following shutdown (1 d - 10 y), SiC offers 3-4 orders of magnitude lower activity compared to FS.

• WC filler generates highest activity.

10-3

10-1

101

103

105

100 102 104 106 108 1010

Act

ivity

(Ci/m

3 )

Time After Shutdown (s)

1h 1d 1w 1y

VV Shield

Coil Case

WP-IWP-II

ExternalStructure

10-1

101

103

105

107

109

100 102 104 106 108 1010

Act

ivity

(Ci/m

3 )

Time After Shutdown (s)

1h 1d 1w 1y

SiC B-I

FS

WC

SiC B-II

Decay Heat

• SiC decay heat drops sharply after shutdown, a salient feature.• WC-shield generates 10 - 1000 times higher decay heat than FW/blanket

@ 1 d after shutdown.• If temperature during LOCA/LOFA exceeds limit, install special loop to

transport decay heat from WC-shield to surroundings.

10-3

10-1

101

103

100 101 102 103 104 105 106 107

Dec

ay H

eat (

W/m

3 )

Time After Shutdown (s)

1h

1d 1w

Coil CaseWP-I

Shield

VV

WP-II

ExternalStruccture

10-2

100

102

104

106

100 101 102 103 104 105 106 107

Dec

ay H

eat (

W/m

3 )

Time After Shutdown (s)

1h 1d 1w

FS

SiC B-I

WC

SiC B-II

Waste Disposal Rating(for Compacted Waste @ 100 y After Shutdown)

• WDR < 1 Class C Low Level Waste (LLW).• SiC-FW/blanket, VV, and magnet qualify as Class A LLW.

SiC System FS SystemReplaceable Components:

FW/Blanket-I 0.03 0.4WC-Shield 0.8 0.6

Permanent Components:Blanket-II 0.06 ---Shield 0.5 0.7Vacuum Vessel 0.02 0.05Magnet < 0.1 < 0.1

Breakdown of Class A and Class C Low Level Waste

0

500

1000

1500

2000

2500Class A WasteClass C WasteTotal

Low

Lev

el W

aste

Vol

ume

(m3 )

SiC System FS System

63% Class A37% Class C

34% Class A66% Class C

Concrete Building can be Cleared Shortly after Plant Decommissioning

• Steel structure of building can be released after 20 y storage period.

• None of the internal components can be cleared from regulatory control.

10-7

10-5

10-3

10-1

101

103

105

100 102 104 106 108 1010

Bio

shie

ld C

lear

ance

Inde

x

Time After Shutdown (s)

1h 1d 1y

Limit

100y

Concrete

Mild SteelStructure

Conclusions

• No major activation problems identified for SiC and FS systems.

• High decay heat identified for WC-shield Special loop will be installed to transfer decay heat to surroundings if

temperature during accident exceeds limit.

• All radioactive wastes qualify as Class A and Class C LLW.

• None of ARIES-CS components can be cleared from regulatory control except building. Concrete and reinforced steel structure can be released to commercial market after ~0.5 y and ~20 y, respectively.