ML20066D055

Special Rept Spr 90-016:on 901203,fire Protection Officer Questioned Position of CO2 Tank Outlet Valve Because of Relationship of Worm Gear & Sector Gear.Caused by Failure to Return Sys to Operable Status on 901031.Valve Repaired

ML20066D055
Person / Time
Site:	Summer
Issue date:	01/02/1991
From:	Skolds J SOUTH CAROLINA ELECTRIC & GAS CO.
To:	Ebneter S NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
SPR-90-016, SPR-90-16, NUDOCS 9101140091
Download: ML20066D055 (2)

Text

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1. South Carolina Doctrlc & oss Company -- John L Okolds _

1. P,0. Box 88 - Vice Preaicent .  ;

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• Jenkinsville, Sc 29065 ' Nucleat Operanons o .

. (803) 345-4040 (

SCEaG;

,4 N 0 21991  ;

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31'JAN7- Pl! j 6- <

'Mr.LS.10. Ebneter

. Regional Administrator j U. S. Nuclear Regulatory Commission

-Region !!,-Suite 2900-  ;

101 Marietta Street NW l

-Atlanta, GA 30323

Dear Mr. Ebneter:

TUBJECT: VIRGIL:C. SUMMER NUCLEAR STATION

-DOCKET N0b 50/395 OPERATING llCENSE NO. NPF-12 SPECIALREPORT_(SPR90-016)(ONO900119)

On:0ecember.-3,- 1990, during performance of.. Surveillance Test Procedure -(STP)-

1128.007 !'C02 Valve Lineup Verification " the Fire Protection Officer (FP0) iquestioned the posi h on M the:CO2 tank outlet valve (XVG-14072). This

' system _provides-fire supprtasion'to the Relay Room.

The operator for this valve consists of a handwheel which turns a v .m gear mated to a sector gear which, in turn, drives the butterfly valve. Slack in-thisfgear assembly was such that the handwheel could be turned approximately fouriturns-before resistance was. encountered. When the handwheel was x operated to the. point that resistance was encou.ntered,'it was believed that .

the' valve was' open. This sequence of events occurred following maintenance

. 1 and-return:offthe system to an operable status on October-31, 1990.. The alignment was second. checked on that-datc.and again on November. 6,1990. On each occasion, the valve was verified tofbe full. opened when resistance was s

encountered.!:The valve had a: locking device which provided indication of the H Lhandwheel travel and:also provided a method for securing-the' valve in the -l t open rostiion.; This locking. device had-been broken several years ago and 1 therefore was'not,available as a means of: determining valveiposition.

On 0ecember 3,.1990, during a monthly inspection, the FP0-questioned the:

1 valve-position-because-of the relationship of the. worm gear and the sector gear.: The_FP0_ believed that the worm gear would be at the end of'its travel

when::the valveL wasl full open. -After relating-this; concern to the Shift

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Supervisor,: permission was given to remove the locking chain (used to replace

broken locking-device)!and-operate-the valve in order to verify the valve.

position. -At the point-in the-_ valve operation-when resistance was-

. encountered, additional: pressure was applied. A slight " pop" was heard and the' gear-assembly _ operated, freely. Once the valve operator was free-of any b uiing, the initial-problem could not be' repeated. :lt should be noted that M ve travel-fromffull close_to full open is-approximately eight to nine

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Mr. S. D. Ebneter ONO (900119)

Page 2 The cause of the event is attributed to a failure to adequately restore the system to operable status. This tailure was caused by a personnel error in the danger tagging restoration sequence. The CO2 outlet bypass valve (XVT-14073) was not utilized to equalize the pressure across XVG-14072 prior to opening.

In addition, determining the correct valve position was hindered by a broken valve position indicator and the uniqueness of the valve (only valve of this type in the plant).

The safety significance of this event is minimal due to the fact that the C02 system was not needed during the time period when XVG-14072 was closed. In addition, other fire protection activities and equipment would have indicated the need for fire suppression actuation.  :

To preclude rec.crence, the licensee is taking the following actions: (A) a Maintenance Work Request has been submitted to investigate the elimination of

" slack" in the valve, (B) a placard is being placed at the valve assembly noting the need to use the bypass valve to equalize and the number of turns required to fully open the outlet valve, (C) a Maintenance Work Request has been written to replace the locking device on the valve, and (D) a copy of this report will be placed in the Operator's Required Reading.

Items B and D above will be completed by January 31, 1991, and actual repairs to the valve will be accom;,lished af ter parts have been obtained and when plant conditions will allow.

Very truly yours, John L. Skolds RJB:JLS: led c: 0. W. Olxon, Jr. Marsh & McLennan R. R. Mahan bicument Control Desk R. J. White lh00 Records Center General Managers ANI ':brary G. F. Wunder ' NSRC C. A. Price NPCF NRC Resident Inspector RTS (0N0 900119)

J. B. Knotts, Jr. File (818.05 & 818.08) l l

l Nuclear Excellence - A Sumer Tradition! l 1

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