ML20024B326
| ML20024B326 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 12/11/1978 |
| From: | Rosalyn Jones BABCOCK & WILCOX CO. |
| To: | Cartin L BABCOCK & WILCOX CO. |
| References | |
| TASK-06, TASK-6, TASK-GB GPU-2447, NUDOCS 8307080414 | |
| Download: ML20024B326 (2) | |
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THE BA'SCOCX & WILCOX 'COMPAtlY POWER GENERATI0li GROUP i
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t..R. CARTI!!. I?t ECP.ATIC'ID IO.j r,c.
888 '*3 8 R.C. JC?iES ECCS A'*AI.YSTS C066) wr>we 1
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. Smt.I _BPIAT. A!!AI.YSE3 WIT 11 RC Pt.*?S PC'TE?ID DECT.n ER 11. 1478
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De Presently approved s=sil break analyses have all been perfor=ed assu=ing
'T that offsite power is lost coincident vittr reactor trip. This results in
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tripeing of the RC pu=ps, actuation of auxiliary feedvater, and control 7
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of the liquid level on the secondary side of the SC at high 1cvels.
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Should offsite power remain available during the transient, the RC pu=ps vill remain powered an.1 the ICS will control the. secondary side water level to e.
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,. s approximately 30 inches by throttling the main (or auxiliary) feedvater.
control valve. Because of the i=portance of,the SC vater icvel> to mitigation E.
-g of.small breaks, ECCS recoc= ends an analysis of the RC pu=ps powered case.
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In making this ree:=endatien. ECCS has perfor=ed a ' review to deterr.ine 2
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what previous analyses are available with.tha RC pu=ps povered a=d also has
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a made an engineering assess =ent of ' hat vould, happen under this situation.
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. No previous analyses could be found.. However, it is expected that if.any 8
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were perfor=ed, they were not done at break sizes of interest. With the I
RC pu=ps pevered, it is expected that natural circulatica vould be esin-
[r tained for a longer period of tice and would' aide system depressurization.
Also, r.aintainance of the systen flev vould decrease Thoc after reacter trip 3
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and would res' ult in a lower pressure for systen flashing. to occur. However.
the's'e positive influences vould be offset by the'. decreased ability of the SC P
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to condense stea=, following tha loss of natural circulation, due to the
-t lover SC level' courrel. It'is also expected that, with the RC p. ps running,
.,{, ah 5 a " steam pocket" will not form in the cold legs and lower quality fluid will b,
exit through the break and thus shorten the time for the system to reach the l'
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" boiling pot" mode' of the transient.. An unknown fsetor at this ti=e is p
whethe'r or. not the? steam generated in the. core vill' separate'in the hot leg a
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,,U-bend or be carried down into'the SG'and. condensed. This may be an ima 5
pg.4* &
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portant factor for showing that the RC pumps runn'ing case is better than the.
present assumption of tripping the RC pu=ps.
ECCS proposes that the impset
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of this phenomens be examined in.4 sensitivity study.
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' ~ As illustrated above. it'is iot obv' ously cles'r' that leaving the RC' pumps.
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NM running results in an enhanted ECCS situation. Thus. ECCS recom= ends.sn
- y p'.@l.ij analysis be.perfor=ed to ex:=ine this case.
EC~.3 proposes that this',
r analysis.bo run on the 205 TA plants for the' following reasons
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RC Jones to 1.1 Cartin Page Two N
Subject:
St-all Break Ansivses With RC Pumns Powered tee. 11. 197S
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ne present 205 FA s=all break topical (EAV-10074) assu=es heat re= oval typical of that for the 177 TA plants. nerefore, a ec=parison of the s
pu=ps on case to EAW-1C074 vill provide an assess =ent of the i= pact on
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the 177 TA plants.
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n ere presently exists an FAC model on the 205 TA plants.
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ne nev SC model in C2AT: has been e.xeteised on the 205 FA plants.
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nis modc1 = ore properly accounts for SC perfor=ance during the tran-
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sient for the 205 FA and VEF0o plants. Ceeparison of the pu=ps on c.ise b
b to recent 2C5 TA plant studies vill provide infor=ati:n on the impact for 205 TA and VEPCo plants.
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It is expected that this work cou'Id be scheduled into.the ECOS Unit workload now because of slippage in the NRC s=all break standard proble= and the 205 1
FA s=all break work. It is esti=ated that this work vill require 300 =h f.
and 10 CDC hours and a span time of 3 months'. Niru Shah vill be the con-T i
tact in ECCS for this issue. If any questions arise, please contact him,
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or call se on extension 2066.
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