BVY-92-068, Documents Request for Temporary Waiver of Compliance from TS LCO Requirements Re EDG Operability.Waiver of Compliance Will Allow One Addl Day to Repair Components & Thoroughly Test EDG Prior to Returning to Svc

Documents Request for Temporary Waiver of Compliance from TS LCO Requirements Re EDG Operability.Waiver of Compliance Will Allow One Addl Day to Repair Components & Thoroughly Test EDG Prior to Returning to Svc

ML20101F281
Person / Time
Site:	Vermont Yankee
Issue date:	06/03/1992
From:	Murphy W VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
BVY-92-068, BVY-92-68, NUDOCS 9206240359
Download: ML20101F281 (3)

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BRMONT YANKEE NUCLEAR POWER CORPORATION y .

• y% Fetry Road. Brattleboro. VT 05301-7002

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ENG!NE ERWG OFTICE 49

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/ .a a i 11 June 3.1992 DVY 92-068 United States Nuclear Regulatory Commission Reglon 1 Administrator 475 Allendale Road King of Prussia,PA 19406

References:

(a) License No. DPR 28 (Docket No. 50-271)

(b) NRC Memorandum from T.E. Murley, Director, Office of Nuclear Reactor Regulation, " Temporary Walvers of Compliance", dated 2/22/90

Subject:

Request for Temporary Walvor of Compliance from Technical Specification LCO Requirements PortainP.g to Emergency Diesel Generator The purpose of this letter is to document our request,in accordance with the guidance provided in Reference (b), for a temporary walver of compilance from Technical Specification LCO requirements for Emergency Diesel Generator operability.

1, Reauirements to be Walved:

Vermont Yankee Technical Specification 3.5.H.1 states the following:

During any period when one of the standby diesel generators is inoperable, continued reactor operation is permissible only during the succeeding seven days, provided that all of the Low Pressure Core Cooting and Containment Cooling Subsystems connecting to the operable diesel generator shall be operable, if this requirement cannot be met, an orderly shutdown shall be initiated and the reactor shall be in the cold shutdown condit!on within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Vermont Yankee is requesting reflof from the 7 day Limiting Condition for Operation of Section 3.5.H.1 for a period of 1 additional day with an emergency diesel generator (EDG) Inoperable.

The waNet would extend the available time to replace engine components and thoroughly test the un!t prior to a return to operable status.

2, Discussion of Circumstances The 'A' Emergency Diesel Generator was declared inoperable on May 28,1992 at 1240 pm.

, During a routine monthly EDG surveillance, a problem was noted with the jacket coolant system and the EDG was therefore declared inoperable pending investigatio" into the cause of the abnormalities. Upon disassembly of the diesel engine, the #7 cylinde met was found to have l

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+ VERMONT YANKLE NUCLE AR POWER CURPORATION l U.S. Nuclear Regulatory Commission June 3,1992 Page 2 a crack. In addition, furtherinspection revealed plating damage of the liner and pltting damage of the upper piston in the #3 cylinder. These Indications were In the combustion area and not in the piston wear ring area.

Both linors and th9 #3 piston will be replaced.

3. Compensatory Actions As required by Technical Specifications, the alternate EDG was satisfactorily tested and all of Pe Low Pressure Core Cooling and Containment Cooling Subsystems connected to this operable EDG were verifled as operable. Additionally, the Vernon Hydro Station was notified I of this situation and the dedicated tie-line to Vermont Yankee was verified as being available.

The Station Manager concurred with our request not to do anything that would jeopardize the tie.llne availability as well as to notify Vermont Yankee of any change in the tie-line status.

It should be noted that use of the Vernon tie line is addressed in operating procedures and operators are trained in its use.

A thorough review of all planned surveillance activities was conducted and only those determined to be of low risk will be allowed. Based upon the short duration of this request, additional alternate testing of the "B" EDG and its subsystems was considered, and determined not to be necessary.

. 4. Safety Stanificance and Potential Conseauences The proposed one day extension has no impact on the consequences of any previously analyzed event if off site power remains available. The alternate EDG was tested for operability prior to requesting the one-day extension period. This gives asturance that the available EDG would function, if required, in addition, the Vernon tie-line, which has historically demonstrated a very high reliab!'Ity, is available to supply power to the emergency bus. The requirements of the Technical Specifications also require that during the one day extenslo" period, all remaining Low Pressure Core Cooling and Containment Coeling systems connected to the operable EDG will remain operable. The proposed change would allow the "A" EDG to remain Inoperable for one additional day. Any accident which could occur during this one-day period could have occurred in the previous seven-day period also. Therefore, the proposed change does not significantly increase the probability of an accident. Since this is an extension of only one day, the increased risk associated with an accident during this period is not significant.

Probabilistic Risk Analysis has estimated that the impact on the expected core damage frequency would be changed by less than 1 percent during the additional one-day extension period.

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I VERMONT YANKEE NL)CLE AR POWER CORPOR ATION U.S. Nuclear Regulatory Commisalon June 3,1992 -

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5. OplMqo_plReove31 The proposed walvor of compilanco is for one time approval of reactor operation for up to eight (0) days with the EDG Inoperable. The current Vermont Yankee Technical Specifl?ations allow roactor operation for soven (7) days with the EDG Inoperable. Vermont Yankee bel' eves that the add!tional one day will provide eufficient margin to repah and thoroughly test the EDG without compromising the continued safe operation of the plant. It should be noted that a signif! cant portion of the extra LCO time would be for "run-In" of the new components and operability testinn. The EDO would be availablo during this period, but not considered eperable.

6. SlonfficanLHarards Coristderation Vermont Yankoo has concludod that the roryuost does not involve u significant hazards consideration in that the request would not: ,

(1) Involve a significant increase in the probability or consequences of an accltient -

proviously ovaluatod As discussed in section 4, a one (t) day extension to an already existing sovon (7) day Limiting Condhlon for Operation would involve an insignificant incroase in tho probablilty of occurrence and consequences of a design ba918 accident i during tho extension period.

01) creato the poosibliity of a no'v or different kind of accident from those previout,fy l

ovaluatod. The proposed ch; age can have no impact on the possibility of a new or different initiating event. Any previously analyzed event postulated during the one-day extension period can be mitigated by tha systema powered by the Vernon tie Ilne.

l 010 involve a s!gnificant roduction in the margin of safety. As discussed above, approval l of th!s request involves an insignificant reduction in the margin of safety because of the availability of other plant oloctrical system's and the chort duration of the extension period. The change will have no significant impact on the consequences of any accident and will have no impact on any protective boundaty.

l In summary tho walvor of compliance would provide a r.on recurring, one-timo approval of reactor operation fcr up to an additional day with the "A" EDO inoperable. The walver of -

compliance would extend the existing Technical Specification LCO through June 5,1992 at 1240 pm. The walvor of compilance will allow an additional one day to repalt components and thoroughly test the EDG prior to returning it to service.-

• The Vermont Yankee Plant Operations Review Committoo (PORC) has revlowed this request i for a temporary walver of compliance and concurs with the determinations presented.

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M ', VERMONT YANKEE NUCLE AR POWER ' ORPOR ATION g U.S. Nucloat Regulatory Commisolon June 3,1992 Page 4

7. Eryfkonmental Conteouences No environrnental consequences will result from approval of this request.

, 8. Notification of State g

Vermont Yankee has notified the State of Vermont of the content of this request and has forwarded a copy of this document to the Vermont State Nuclear Engineet.

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lt la our understanding that this request for a one-dey temporary walver of compilance has beon authorized by telecon on June 3,1992 by James C. Unville (USNRC) to Donald A. Reid (VYNPC).

We trust that the Information provided adequately supports our request; however should you havn any questions regarding this mattor, please contact this office.

Very truly yours, Vermeat Yankee Nuclear Power Corporation l 4"l N Warren P. Mufphy I" (

' Senior Vice President, O r tio s n,

cc; USNRC Document Control Desk USNRC Director, NRR USNRC Director, Reactor Projects, NRR USNRC Director Office of Enforcement USNRC Technical Assistant, Reactor Projects, NRR

- USNRC Resident inspector (VYNPC)

USNRC Project Manager, NRR VT Dopartment of Public Service I'

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