ML20148F289

Unusual Event:During ECCS Two Train Pump Flow Review, Accident Analysis Assumptions Not Supported by Data. Operation at or Below 11.6 Kw/Ft Will Maintain All Safety Margins.Westinghouse Investigating Problem

ML20148F289
Person / Time
Site:	Yankee Rowe
Issue date:	12/11/1974
From:	Heider L YANKEE ATOMIC ELECTRIC CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
WYR-74-52, NUDOCS 8011040743
Download: ML20148F289 (3)

Text

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,,,. , n . s , n YAN/WE MOMiG ELECLIC COMPANY h

WYT. 74-52 r__7__'*

20 Turnpske Road Wessborough, Mossochusetts 01581

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Deceinber 11, 1974 E,_- . U '"

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Unitod States Ator.ic Ir. orgy Consnission ~

Directorate of P.egulatory Cperations .

Region I G31 Park Avenue k

King of' Prussia, Pennsylvania 19406

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Attention. James P. o'neilly, Director THIS DOCUMENT CONTAINS neference, ueense so. DPR-3 (Docket No. 50-29)

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In accordance with Section E.2.b, Appendix "A" Technical Speelfications of the Reference License the following Unusual Event is reported. k I

A review of ECCS two train pump flow indicated that the data did not support the assumptions used in the accident analysis. In fact, the flow ((

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for two of the three trains as determined from s;hield tank cavity level change followst and the average flow as measured by the flow instrumentation is as . .

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cavity Level change Ins trurwnta tion I

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Tratna 1 ard 2 2290 vpm 2100 gpm 1-Trains 2 and 3 2278 gpm i Trains 1 and 3 2220 gra -

2271 gpa 2320 gpn hse VCues are consistent with the initial design criteria .

energency core cooling system. However, for the

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Westinghouce in the Eccs analysis was 2400 gpm.theThis two was trainanpump input flow used by error. }

The taxh allovable peak linear heat generation rate calculated for the Yankee Rove core using this erroneous value was 13.06 kv/ft.

When this error was veri.fied, the plant was administratively derated to 90 % o f f ull powe r (a resultant power level of $40 MVt) as a conservative (

wacure pending further investigation. This investigation by Yankee Atomic Eloctric Corpany has concluded that operation at er below 11.6 kv/f t will conservatively r.aintain all safety margins previously indicated in the Et"TS cnalyses.

In-core teeasurnments at the plant verity that the 11.6 kw/f t linear heat generation rate lini,t will not be exceeded by operation at 1004 plant output (600 MWt). Plant output was accordingly increased to icos on December 9,1974.

h Directorate of Licensing was inforr.ed of the i

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United States Atonic Energy Cersnission Deceanber 11, 1974 Attns James P. O'Reilly, Director page Two probica and Yankee Atoetic Electric coespany inmediately began preparation of a cupplerent to our Proposed Change No.117 to account f'or the error.

A review of Core M' operating data confirms that the peak linear heat generation rate did not exceed 11.6 kw/f t durin7 that cycle. During the i period. between Septear.ber 9,1974, and Decociser 6, 1974, the conservative

• I limit of 11.6 kw/f t was exceeded at some points. -It should be recognized E that until the results of a revised ECCS analysis are available, it cannot i be concluded that the operating conditions during that period were such l that the applicable ICCS criteria were, in fact, not met. , l We are currently discussing the problem with Westinghouse and desire to have a revised analysis perforr.ed as soon as possible. The resulta vill be submitted to the Directorate of Licensing as soon as they are -

availcble and we shall keep the Dire ctorate of Licensing inforned as to r.chedule . .

.Very truly yours, .

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YAMKEE ATONIC ELECTRIC ANY -

L. H. Raider Asst. Vice President.

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' ** EC DIST, UTIDN FOR ? ART 50 DOCKET .1kRI AL, (T E T.;F O R A R Y. F O R T.;) l CONTROL NO: 127h3 FILE: m  !

DATE OF COC D ATE R EC'D LTR T'.'lX RPT OTHER FRO?.1: Yankee Atomic Elec. Co.

Westborough, Mass. 01581 X  !

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CLAS$ U ! CLASS 1 50-29 XXX Ltr reporting an Unueual Event ENCLOSURES:

DESCRI?TiO:::

involving ECCS two train pump flow indicated in that the data did not support the assumptions ased in the accident analysis..... n- n ,

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