ML20097D878
| ML20097D878 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| 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 9206110177 | |
| Download: ML20097D878 (4) | |
Text
%,
m jo VERMONT YANKEE NUCLEAR-POWER CORPORATION 3
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.. g 3 Ferry Road, Brattleboro, VT 05301-7002
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ENGINE If OFFICE
$80 V A!N STREET BOiTON VA01!at f'
l$ % 7794't1 June 3,1992 BW 92-068 i
United States Nuclear Regulatory Commission Region i Adminit>trator 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 r
Regulation, "Temporarv Walvers of Compliance", dated 2/22/90
Dear S;r:
Subject:
. Request for Temporary Walver of Compliance from Technical Specification LCO Requirements Pertaining to Emergency Diesel Generator.
,.The purpose of this 'etter is to document our request, in accordance with the guidance provided in Reference (b), for a temporary walver of complianc? from Technical Specification LCO requirements for Emergency Diesel Generator operability.
,1,1
. Reaulrements to be Walvedi Vermont Yankee Technica! Specification 3.5.H,$,tates the following:
During any period when one of the standby diesel generators is inoperable, continued reactor operation is permissible only during the succeeding se"en days, provided that all of the Lcw
- Pressure Core Cooling and Containment Cooling Subsystems connecting to the operable diesel generator shall be operable. If this requirement cannot b3 met, an orderly shutdown shall be initiated and the reactor shall be in the cold shutdown condition 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 relief from the 7-day Limiting' Condition for Oper tion of Section 3.5,H,1 for a period of 1 additional day with an emergency diesel genera *or (E 1) inopable.
.The waiver would extend the available time to replace engine components and uoroughly test the unit prior to a reteni 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 noteo with the Jacket coolant system and the EDG was therefore declared. inoperable pending investigation into the cause of the abnormalities Upon disassembly of the diesel engine, the #7 cylinder liner was found to have 9206110177 920603
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VERMONT YANKEE NUCLEAR POWER CORPORATION U.S. Nuclear Regulatory Commission June 3,1992 Page 2 a crack. In addition, further inspection revealed plating damage of the liner and pitting damage of the upper piston in the #3 cylinder. Thes,e indications were in the combustion area and not in the piston wear ring area.
Both liners and the #3 piston will be replaced.
3.
Compensatory Action 3 As required by Technical Specifications, the alternate EDG was satisfactorily tested and all of
- the Low Pressure Core Cooling and Containment Cooling Subsystems connected to this operable EDG we,e verified as operable. Additionally, the Vernon Hydro Station was notified of this situation ar'd 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-line 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 Cperators 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 alternale testing of the "B" EDG and its subsystems was considered, and determined not to be necessary.
4.
Safety Slonificance and Potential Consecuences The proposed one day extension has no impact on the consequences of any previouslr analyzed event if off-site power remains available. The alternate EDG was tested for operabilin prior to re;aesting the one-day extension period. This gives assurance that the available EDG would function, if required. in addition, the Vernon tie-line, which has histnrically demonstrated a very high reflability, is available to supply power to the emergency >.
'he requirements of the Technical Specifications also require that during the one-c v t.ension period, all remaining Low Pressure Core Coohng and Containment Coothg sg
.s connected to the operable EDG will remain operable. The peoposed 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 w'h an accident during this period is not significant.
Probabilistic Risk Analysis has estimated that the impact on the expectec' core damage frequency would be changed by less than 1 percent dL ng the additional one-day extension d
period.
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VERMONT YANKEE NUCLEAR POWER CORPORATION U.S. Nuclear Regulatory Commission June 3,1992 Page 3 5.
Duration of Recuegl The proposed walver of compliance is for one-time approval of reacter operation for up to eight (8) days with the EDG inoperable. The cu cent Vermont Yankee Technical Specifications allow reactor operation for seven (7) days with the EDG inoperable. Vermont Yankee believes that the additional one day will provide sufficient margin to repair and thoroughly test the EDG -
without compromising the continued safe operation of the plant, it should be noted that a significant portion of the extra LCO time would be for 'run-In* of the new components and operability testing. The EDG would be available during this period, but not considered operable.
6.
Stanificant Hazards Consideration Vermont Yankee has concluded that the request does not involve a significant hazards consideration in that the request would not:
(1) -
Involve a significant-Increase in the probability or consequences of en accident previously evaluated. As discussed in section 4, a one (1) day extension to an already existing seven (7) day Limiting Condition for Operation would involve an insignificant increasa In the probability of occurrence and consequences of a design basis accident during the extension period.
Ol) create the possibility of a new or different kind of accident from those previously evaluated. The proposed change 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 the systems powored by the Vernon tie-line.
0 11) involve a significant reduction in the margin of safety. As discussed above, approval of this request involves an insignificant reduction in the margin of safety because of the
~
aval! ability of other plant electrical systems and the shor' duration of the extension penod. The change will have no significant impact on tne consequences of any accident and will have no impact on any protective boundary, in summary, the walver of compliance would provide a non-recurring, one-time approval of l:
reactor operation for Up to an additional day with the "A" EDG inoperable. The waiver of L
compliance would extend the existing Technical Specification LCO through June 5,1992 at j;
1240 pm. The walver of compliance will allow an additional one day to repair components and thoroughly test the EDG prior to returning it to service.
The Vermont Yankee Plant Operations Review Committee (PORC) has reviewed this request for a temporary walver of compilance and concu.s with the determinallons presented.
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VERMONT YANKEE NUCLE AR POWER CORPOR ATION U.S. Nuclear Regulatory Commission
- June 3,1992 Page 4 7.
Environmental Conseouences No environmental consequences will result from approval of this request.
8.
Notification of State 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 Engineer.
It is our understanding that this request for a one-day temporary waiver of compilance has been authorized by telecon on June 3,1992 by James C. Linville (USNRC) to Donald A. Held (VYNPC).
We trust that the information provided adequately supports our request; however should you have any questions regarding this matter, please contact this office.
Vcry truly yours, Vermont Yankee Nuclear Power Corporation W
V*
Warren P, by Senior Vice esident, O r tio s cc:
USNRC Doc 0 ment Contr$1 De$
USNRC Director, NRR USNRC Director, Reactor Projects, NRR USNRC Director, Office of Enforcement USNRC Technical Assistant, Reactor Projects, NRR USNRC Resident inspector (VYNPC)
VT Department of Public Service-
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