ML20198G225

Discusses Util 850117 Request for Fatigue Cumulative Usage Factor Limit Relaxation.No Basis Exists for Deviation from SRP 3.6.2 Criteria.Request Unacceptable

ML20198G225
Person / Time
Site:	Columbia
Issue date:	11/18/1985
From:	Bosnak R Office of Nuclear Reactor Regulation
To:	Novak T Office of Nuclear Reactor Regulation
References
CON-WNP-0843, CON-WNP-843 NUDOCS 8511210563
Download: ML20198G225 (2)

Text

,s i ,F N O V 1 E t. g MEMORANDUM FOR: Thomas M. Novak, Assistant Director for Licensing Division of Engineering FROM: Robert J. Bosnak, Acting Assistant Director for Components and Structures Engineering Division of Engineering

SUBJECT:

WNP-2 REQUEST FOR FATIGUE USAGE LIMIT RELAXATION

Reference:

Letter from G. C. Sorenson to A. Schwencer, " Nuclear Plant No. 2 Request for Fatigue Usage Limit Relaxation" dated January 17, 1985 To conform with Standard Review Plan 3.6.2, " Determination of Rupture Locations and Dynamic Effects Associated With the Postulated Rupture of Piping," a break must be postulated in any ASME Class 1 high energy piping system in which the fatigue cumulative usage factor exceeds a value of 0.1.

In the referenced letter, the applicant has requested that this usage factor limit be relaxed from 0.1 to 0.4 for those portions of the WNP-2 Reactor Feedwater (RFW) Piping located between the containment isolation valves.

The applicant's basis for this request is that to preclude exceeding the 0.1 limit, use of the RRl has been restricted, which places unnecessary dependence upon safety system: for maintenance of core coverage. The applicant has further stated, however, that the 0.1 usage factor limit may only be marginally exceeded in its ongoing RRl re-analysis. The staff assumes that this re-analysis includes transients applicable to the 40 year lifetime of the plant.

The staff's position relative to this plant-specific request is as follows:

1. There is no basis at this time for the staff to deviate from the Standard Review Plan 3.6.2 criteria. Therefore the requested increase in usage factor from .1 to .4 is not acceptable.

2. The staff does not agree that the licensee should continue to operate its plant in an undesirable manner just to avoid exceeding the .1 limit.

The licensee should operate its plant in the safest possible manner keeping a record of the accumulated usage factor at critical locations.

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3. If, after some period of operation, the .1 usage factor limit appears to be imminent at any location, the licensee should notify the staff and a decision will be made on a case by case basis whether to allow an increase in the limit. It is the staff's understanding that it will be a number of years before the .1 limit will be exceeded in the RFW.

CONTACT: Y. Li, DE:MEB 49-24417 l

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Thomas M. Novak .

2 It should be noted that ANSI /ANS-58.2, "American National Standard Design Basis for Protection of Nuclear Power Plants Against Effects of Postulated Pipe Rupture" is currently being revised to address this specific issue and that the staff is participating in this effort. The staff anticipates that this work will result in a relaxation of the .1 limit.

Please transmit this response to the licensee at your earliest convenience.

Robert J. Bosnak, Acting Assistant Director for Components and Structures Engineering Division of Engineering cc: J. Knight, DE W. Butler, DL F. Cherny, DE B. Sheron, DSI W. Hodges, DSI S. Hou, DE J. Bradfute, DL D. Terao, DL H. Brammer, DE R. Li, DE e

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