ML20205C083

Forwards Request for Addl Info Re Tech Spec for Svc Water Sys Limiting Condition for Operation.Request Based on audit-type Review for Both Fault Trees & Resultant Minimal Cutsets.Response Requested within 2 Wks.W/O Encl

ML20205C083
Person / Time
Site:	North Anna
Issue date:	08/09/1985
From:	Butcher E Office of Nuclear Reactor Regulation
To:	Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
References
NUDOCS 8509200080
Download: ML20205C083 (2)

Text

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'- Docket Nos. 50-338 August 9,1985 and 50-339 Mr. W. L. Stewart Vice President - Nuclear Operations Virginia Electric and Power Company Post Office Box 26666 Richmond, Virginia 23261

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION REGARDING TECHNICAL SPECIFICATION i

TS) FOR SERVICE WATER SYSTEM (SWS) LIMITING CONDITION FOR OPERATION LCO) - NORTH ANNA POWER STATION, UNITS NO. 1 & NO. 2 (NA-182)

By letters dated March 29, 1985 and July 1,1985, you proposed a change to the NA-182 TS which would extend the LCO for one SWS header from 72 to 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br />. Specifically, the proposed change would extend the allowable time that one of the redundant SW hedders can be inoperable beyond 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> up to 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br /> provided three out of four SW pumps and one out of two auxiliary SW pumps are operable during the LCO.

Your safety evaluation justifying the extended LC0 was based on a probabilistic risk analysis which concluded that the probability of failure of the SWS to provide adequate flow during the extended LC0 would be reduced below the failure probability for the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> LC0 allowed by the current NA-182 TS.

In order to validate your safety evaluation, we require additional information so that we can fully understand the details of the NA-182 SWS probabilistic risk analysis. The request for additional information is provided in the enclosure to this letter. The request for information is based on the staff's audit-type of review for both the fault trees and resultant minimal cutsets.

It is noted that the additional information provided must adequately address our concerns; otherwise, we will not be able to arrive at a conclusion, based on a probabilistic assessment, as to the acceptability of extending the SWS  !

header LC0 to 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br />.

We have already discussed the need for additional information with your staff by telephone. In addition, in order to expedite the NA-1&2 SWS TS change, we' l have discussed a suitable turnaround time for your response. Based upon these conversations with'your staff, we therefore request that your response be provided within 2 weeks of your receipt of this letter.

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. This request for information affects fewer than 10 respondents; therefore, OMB clearance is not required under P.L.96-511.

Sincerely,

/S/

Edward J. Butcher, Acting Chief Operating Reactors Branch No. 3 Division of Licensing

Enclosure:

As stated cc w/ enclosure:

See next page Distribution:

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