ML20196K663

Safety Evaluation Supporting Licensee 990520 Position Re Inoperable Snubbers

ML20196K663
Person / Time
Site:	Mcguire, Catawba, McGuire
Issue date:	07/07/1999
From:	NRC (Affiliation Not Assigned)
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ML20196K644	List: ML20196K663
References
NUDOCS 9907090261
Download: ML20196K663 (3)

Text

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e* q , UNITED STAT IS .

g , NUCLEAR REGULATORY COMMISSION 2 - WASHINGTON. D.C. 20525 0001

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION CATAWBA AND MCGUIRE NUCLEAR STATIONS

. ' LICENSEE'S POSITION REGARDING SNUBBERS DOCKET NOS. 50-369. 50-370. 50-413. AND 50-414

1.0 INTRODUCTION

On September 30,1998, the NRC staff issued Amendment Nos.173 and 165 to Catawba Nuclear Station, Unit 1 and 2, respectively. On the same day, the staff issued Amendment Nos.

184 and 166 to McGuire Nuclear Station, Unit 1 and 2, respectively. These amendments converted the Technical Specifications (TS) (Appendix A of the operating license) of Catawba and McGuire, respectively, to the format specified by NUREG-1431, " Standard Technical Specifications - Westinghouse Plants." The amendments were in response to Duke Energy Corporation's (the licensee) applications dated May 27,1997 (one each for Catawba and McGuire), and supplements.

Among the many things accomplished in the conversion was the relocation of TS for snubbers from the TS.

By letter dated May 20,1999, the_ licensee communicated its position conceming inoperable -;

anubbers. The staffs evaluation of the licensee's position follows. [ Note that the licensee used "TS" to represent both the document Technical Specifications, and an individual requirement in the document Technical Specifications. The statYfollows the same practice in this safety

- evaluation since the context in which "TS"is used makes its meaning clear.)

4 2.0 EVALUATION in the May 20,1999, letter the licensee stated that:

LCO [ Limiting Condition of Operation) 3.0.6 only applies to those support systems which have their own TS. For support systems which are not in TS, it is Duke

. Energy Corporation's understanding that when a supported system is made

. inoperable due to a non-TS support system being inoperable, the TS conditions and required actions for the supported system are required to be immediately entered.

? The staff agrees with this interpretation of LCO 3.0.6.

- However, the letter then attempts to justify an exception to the position given above, stating that the position does not apply to snubbers. The only basis the licensee gave to support treating -

snubbers differently is that neither the licensee's amendment requests (May 27,1997, letters i 9907090261.990707 PDR ADOCK 05000369 P- -PDR ,

j

cited above) nor the staff's Safety Evaluation in support of the TS conversion amendments discussed the impact of relocation of the snubber TS.

- The staff does not agree that any exception is warranted. The fact that the impact of a change

-. was not fully discussed or understood is not an adequate basis for creating an exception. The snubber TSs were relocated from the Catawba and McGuire Technical Specifications and thus snubbers are no longer a support system with their own TS. Therefore, should a snubber (s) cause a supported system to be inoperable, consistent with the position stated earlier, the supported system specifications would apply. As a practical matter, the staff does not believe I that the relocation of the snubber TS and subsequent application of LCO 3.0.6 have a significant impact on how snubber operability issues should be handled.

In Generic Letter (GL) 91-18 the staff stated its position as to what constitutes timeliness that is commensurate with the potential safety significance of the issue. In such context, the staff's position would allow up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to replace or restore to operability and evaluate an inoperable snubber. Therefore, to the extent the licensee now uses the relocated specification as guidance as to what constitutes an acceptable maximum evaluation period after which inoperability of the supported system must be declared, the staff sees no problem. However,  ;

. the staff does not necessarily agree with the licensee that "the snubber SLC (Selected Licensee  ;

Commitments] is applicable in the same manner as the snubber TS was.u_gd [ emphasis added]

before ITS implementation." l in the Background section of the subject letter, Duke states that "Under the snubber TS,

. Catawba and McGuire had always taken the position that since snubbers had their own l separate TS, the 72-hour allowed outage time for inoperable snubbers could be utilized before  !

having to declare any supported components or systems inoperable as a result of inoperable snubbers." If this statement is meant to imply that the full 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> could be taken under all  !'

circumstances then it is incorrect. The 72-hour allowed outage time was provided to ensure that overly conservative operability determinations were not made on supported systems where one or a few of many snubbers on a system were found to be inoperable and the effect on the supported system was unclear. However, if the results of the evaluation required by the 1 Functional Test Failure Analysis provisions of the snubber TS (TS 4.79.g of NUREG-0452, Rev. 4) demonstrated prior to the end of the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> that supported components or systems governed _by TS were made inoperable by the inoperable snubbers and those snubbers had yet i to.be restored or replaced, then the supported system TS should have been entered at that time and not at the end of the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Similarly, if the sheer number of snubbers that were inoperable made it apparent, even without completion of the evaluation, that the supported system was inoperable, the supported system LCO should have been entered without delay.

A duration of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> was a reasonable maximum time to restore or replace and evaluate snubbers when the snubbers had their own TS. The principle remains so even though the snubber TS has been relocated. Supported systems have always been required to be declared inoperable at the time when their support systems are determined to have rendered the supported system inoperable. This interpretation is consistent with the longstanding definition o,f Operability, the guidance of GL 91-18, LCO 3.0.6, and the Safety Function Determination Program (see LCO 3.0.6 of the Catawba and McGuire Technical Specifications), as well as with the position taken by Duke Energy Corporation that is cited above. The relocation of snubber

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l TS from the Technical Specifications has not changed the relationship between support and supported systems, and it does not create an exception to TS 3.0.6.

3.0 CONCLUSION

The staff agrees with the licensee's general interpretation of Technical Specification LCO 3.0.6,

'but finds no technical basis or guidance that snubbers could be treated as an exception to the general interpretation. The relocation of snubber TS from the Technical Specifications has not changed the relationship between support and supported systems, and it does not create an l

exception to TS 3.0.6. '

Principal Contributor: James G. Luehman

.o Date: ' JUL 0 7193g I