ML20084C751

Preliminary AO 50-219/74/46:on 740826,one Torus Drywell Vacuum Breaker Failed to Demonstrate Operability.Caused by Excessive Friction in Valve Hinge Pins.Bushing Difficulty Discussed W/Atwood & Morrill Co,Valve Manufacturer

ML20084C751
Person / Time
Site:	Oyster Creek
Issue date:	08/27/1974
From:	Carroll J JERSEY CENTRAL POWER & LIGHT CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20084C738	List: ML20084C734 ML20084C751
References
AO-50-219-74-46, NUDOCS 8304080198
Download: ML20084C751 (4)

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. Jane Dire O'iteilly

rato of Reguistory Operations-kE k -

Region I 631iPark Avenue ,

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. King of Prussia,, Pennsylvania 19406

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From: Jersey: Central Power 6 Light Company. -

Dyster Creek Nuclear Generating Station Docket #50-219 Forked River, New Jersey 08751 r

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Subject:

Abnormal Occurrence Report No. 50-219/74/46 ,I 4

'the following is a preliminary report being submitted in compliance with.the Technical Specifications, .

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paragraph 6.6.2. ..s s Preliminary Approval: ,,

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. / b 8/27/74'.' .

J. .T4 Carroll,1 Date

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Initial Telephone . g.% ' Date of * -

Report Date: . __ 8/26/74 Occurrence: 8/26/ 74 Initial Written .

h Time of  :

Report Date: . 8/27/74 Occurrence: 1400

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.CYSTER CREEK. NUCLEAR ENERATING STATION PORKED RIVER, NEW JERSEY 08731 Abnormal Occurrence

Report No. 50-219/74/ 46_ ,

IDENTIFICAUIN Failure of one. torus to drywell vacuum breaker to demonstrate OF OCCURRENG: ,

, operability. -

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'This event is considered to be an abnormal occurrence as de-

fined.in. the Technic'ai Specifications, paragraph 1.1SD.

CONDIT1WS PRIOR x Steady State Power Routine Shutdown TO OCCURRENCE: Hot Standby .

Operation

/. Cold Shutdown Load Changes During Refueling Shutdown , Routine Power ~ Operation

. Routine Startup Other (Specify)

Operation

'Ihe major plant parameters at the time of the event were as

. follows:

Power: ~

Core, 1906 FWt

> Electric, 636 FWe .

. Flow: Recirc.,15.4 X 104 gpm Feed. , 7.17 X 106 lb/hr -

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. Stack Gas: 13,175 pCi/sec M DESCRIPTIW On Monday, August 26,1974, 'at approximately 1400, while per-0F OCCURRENG:

" forming surveillance testing on the 14 torus to drywell vacuum breakers, -it was found that one vacuum breaker (V-26-13) failed to demonstrate operability. Excessive force had to be

, applied to effect valve movement when V-26-13 was manually -

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ened and closed.

. und-- ^ho influ:nce of grcvity alons t is noted hsro that V-26-15 was found to be scated prior to testing, as indicated by the recently installed valvo position indicating system.

The valve was setored'in.the closed position soon after t,his ,

problem was identified.

APPARENT CAUSB x Design Procedure OP OCCURRENCB: Manufacture Unusual Service Condition Installation / Inc.. Environmental Construction Component Failure Operator ___ Other (Specify)

It is believed that this failure is attributed to excess friction in the valve hinge pins. .

ANALYSIS OF The-drywell-torus vacuum breaker system is required to prevent OCCURRENCE:

water oscillation in;the downcomers due to low steam flow rates in the downconers and to provido protection against negative pressure conditions in-the containment vessel. The. significance i ,

of this event is minimal in that-the bases of the Technical 3

Specifications state that. one inoperative valve reduces the ..

total vacuum relief' area by.7% and that about 25% of the avail-able vacuum relief capacity ,is;r$ quired Io provide negative pressure protection.

'The drywell-torus vacuum breaker valves are required to be

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( closed during pipe break accidents (particularly small breaks) to-ensure proper steam condensation.and. prevent torus overpres- ,

suring. This valve would have performed this function, if re-quired. p.c ,.y 3:'.

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with Q vacuum breskor valvo tsflengings'at.ssveral fac-111 ties, including Oyster Creek. 'the bushing difficulty has been discussed.with the valve manufacturer (Atwood 4 Norril!

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. Company) and a proposal for a long-term solution is expected Eto be received from ..

the manufacturer. within the next month.

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It:is: noted here that. the bushings.in each torus to drywell

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vacuum breaker valve were inspected and measured'during:.the

,19,74. refueling, outage.. Prior to valve reas'penbly, bushings

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in 11 of the 14 valves, including V-2613, were machined to

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obtain acceptable bushing.I.D. - shaft 0.D.. clearances.. '

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c, _ _ _s. . se FAILURB DATA: ' B.asic valve data are as follows: * ,. ,

m Manufacturer - Atwood.6 Norrill Type - Check Valve-l7' Vent Area.- 1.75 square feet per valve, .,

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Previous abnomal occurrence repo'rts.il involving".;thehejvacuun ,

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Ibreaker valves.are:: '""3..,, ... , m

1. Abnomal,0ccurrence Report No. 73-2. '. s

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2., Abnormal Occurrence Report No. 74-11

,, 3.- Abnormal Occurrence Report No. 74;14.

44.. Abnomal Occurretice Report No.,74L15.,.. .

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