1TPL Dismantling Project Review 08/12/06 Bernard Pégourié

TORE SUPRAAssociationEURATOM-CEA

D program:Specific experiments before dismantling

Purpose: find/or not significant D amount in the CFC explain the lacking D in TS particle balance Can we close the particle balance as it is ? or Do we need specific experiments ?

2TPL Dismantling Project Review 08/12/06 Bernard Pégourié

TORE SUPRAAssociationEURATOM-CEA 1-discharge particle balance

These conditions: retained flux : 21020 D/s

Flux

Gas puff

Paroi

Pompes LPT+tore

Plasma

Post-discharge outgassing

1.5

1.0

0.5

0.0

puf

f (P

am3 s-1

)

300250200150100500

Time (s)

# TS_30425 # TS_30067 # TS_30399 # TS_30414 # TS_30448

3TPL Dismantling Project Review 08/12/06 Bernard Pégourié

TORE SUPRAAssociationEURATOM-CEA 1-day particle balance

1200

1000

800

600

400

200

0

Par

ticl

es (

Pam

3 )

15:00 16:00 17:00 18:00 19:00 20:00 21:00Time (h)

Total Injected Pumped by the limiter Outgased between discharges Total exhausted

Tore Supra experiments

4th

December 2003 7 discharges

7 x 200 s ~ 1400 s of plasma

2.5x1023D

350

300

250

200

150

100

50

0

Par

ticle

s (P

am3 )

60x103

50403020100

Time (s)

Total injected Total Exhausted (limiter) Outgasing between discharges Total exhausted

15 x 20 s ~ 300 s of plasma

Short pulses:

particle balance closed with He glows

Long pulses:

significant contribution to wall inventory

6h of He glows : 1.5-2x1022 D recovered

2.5x1022D

4TPL Dismantling Project Review 08/12/06 Bernard Pégourié

TORE SUPRAAssociationEURATOM-CEA global particle balance

WI = period(Qinj–Qexh)- periodQglow - periodQdisrpt - …)

No reliable estimation of the wall inventory probably > 81023 D atoms

Qinj – Qexh ~ 21020 /s for long discharges (LD)

< 1-21019 /s for short discharges (SD)

Qglow 21022 for a night of glows

Qdisrpt ~ 1021-51022 per disruption

End of 2004 : 3104 s of plasma, of which 4.5103 LD WI ~ 81023 ??? D atoms (Tsitrone, IAEA2004)

Now : 2 years, i.e. > 3104 s of plasma later SD ???

5TPL Dismantling Project Review 08/12/06 Bernard Pégourié

TORE SUPRAAssociationEURATOM-CEA

C-layers in the close SOL: [D]/[C] ~ 1-10 %C-layers in the far SOL: [D]/[C] ~ 10-25 %

• surface/thickness of carbon layers difficult to assess• strong assumption on the D concentration profile• complete collection of carbon layers not unrealistic

Deposited C-layers found in different places (Brosset, PSI2006)TPL (upper surface / back of the tiles)neutralisersoutboard movable limiterLH launcherPoloidal inner bumpersWater-cooled copper tube of protection against ripple electrons

Importance of co-deposition

Post-mortem analyses: inventory 1023 DPresent day wall inventory: > 8 x 1023 D

> 7 x 1023 D still missing

6TPL Dismantling Project Review 08/12/06 Bernard Pégourié

TORE SUPRAAssociationEURATOM-CEA Why a dedicated experiment ?

Good indication that deep diffusion plays a roleD-implantation in CFC does not saturate (J. Roth)

[D]/[C] ~ 0.1-1 % up to 10 m in AUG tiles

in Tore Supra PFCs : ~ 1028 C atoms[D]/[C] ~ 0.01 % in the whole PFCs[D]/[C] ~ 1 % 1 mm in the loaded zones of TPL

to account for present WI

But: no accurate value for present wall inventory Impossible to close reliably the particle balance

possibly dominated by LD performed 4 years ago Low [D]/[C] if diluted in large volume

Necessity of dedicated experiment to charge the TPL in Din a controlled way and with accurate particle balance

7TPL Dismantling Project Review 08/12/06 Bernard Pégourié

TORE SUPRAAssociationEURATOM-CEA What do we need ?

Requirement: WI >> estimated present WI 8x1023 D

For good accuracy : WI ~ 4x1024 D (~ 5 x WI)

Retained flux ~ 2x1020 /s -> 2x104 of LD (equivalent to a year of

operation)…rough estimate… 160 LD of 2 min ~ 11 days of operation (15 LD/day)

Routine LD scenario: nl ~ 2x1019 m-2

Ip = 0.6 MA PLH ~ 2.5 MW

8TPL Dismantling Project Review 08/12/06 Bernard Pégourié

TORE SUPRAAssociationEURATOM-CEA Why a better accuracy ?

WI = period(Qinj–Qexh)No He-glows and (hopefully) no disruptions

Characterization of the plasma outflux out and recycling:Langmuir probesH, CII, (CD ?)Time-dependence of Qinj, Qexh, retention, deposits…

(constant or changing with time / discharge n° ?)Incident flux distribution onto the TPL

…size of the reservoir if saturation observed…dependence of retention with fluence ???

(difficult because limited range of out in loaded regionsand presence of deposits in shadowed regions)

Extrapolated [D]/[C] to the TPL ~ period(Qinj–Qexh)

9TPL Dismantling Project Review 08/12/06 Bernard Pégourié

TORE SUPRAAssociationEURATOM-CEA Main arguments

Particle balance during 1 discharge or 1 day is accuratebut we cannot estimate reliably the wall inventory overlong periods (i.e. the total wall inventory).

Significant improvement obtained by charging the wall in a controlled manner, up to values > the estimated totalwall inventory.

This can be done in about two weeks of long-dischargeoperation (well developed scenario).

Extrapolation of D content of analysed tiles can bequantitatively compared to measured integrated retention.

10TPL Dismantling Project Review 08/12/06 Bernard Pégourié

TORE SUPRAAssociationEURATOM-CEA Injection of C13H4 as a tracer

Injection C13H4 Line ‘impurities’: bumpers, outer wall, TPL

Only long distance C-transportHow much C13H4 to be measured ?

Only TPL:No toroidal distributionC(loaded) C(shadowded)

TPL + tiles (bumpers, LPA):Poloidal & toroidal distributions

More interesting but…How many tiles available ???More analysis, activation ???… if possible, needs a more detailed evaluation