ML20206H493

Safety Evaluation on Generic Ltr 83-28,Item 4.2.3 & 4.2.4, Preventive Maint Program for Reactor Trip Breakers/Life Testing. Licensee Position Unacceptable

ML20206H493
Person / Time
Site:	Beaver Valley
Issue date:	06/19/1986
From:	NRC
To:
Shared Package
ML20206H497	List: ML20206H493 ML20206K123
References
GL-83-28, NUDOCS 8606260145
Download: ML20206H493 (4)

Text

. . Enclosure DRAFT SAFETY EVALUATION REPORT BEAVER VALLEY, UNIT 1 REACTOR TRIP SYSTEM RELIABILITY .

ITEMS 4.2.3 AND 4.2.4 0F GENERIC LETTER 83-28

1. INTRODUCTION On July 8,1983, the Nuclear Regulatory Conunission (NRC) issued Generic Letter (GL) 83-28. This letter addressed intermediate-term actions to be taken by licensees and applicants aimed at assuring that a comprehensive program of preventive maintenance and surveillance testing is implemented for the reactor trip breakers (RTBs) in pressurized water reactors. In particular, Item 4.2 of the letter required the licensees and applicants to submit a description of their preventive maintenance and surveillance program to ensure reliable reactor trip breaker operation. The description of the submitted program was to include the following:

GL, Item 4.2.3 Life testing of the breakers (including the trip attachments) on an acceptable sample size.

GL, Item 4.2.4 Periodic replacement of breakers or components consistent with demonstrated life cycles.

Duquesne Light, the licensee for Beaver Valley, Unit 1, submitted a response to the Generic Letter on November 4, 1983. This report presents an evaluation of the adequacy of that response and of the licensee's life

, testing and periodic replacement programs for RTBs.

2. EVALUATION CRITERIA 2.1 Life Testing Program The requirement for life testing of the RTBs is specified by Item 4.2.3 of the Generic Letter. The purpose of the life testing is to identify a qualified life for the RTB or any of its replaceable components as required by 10 CFR 50.55a(h). By definition qualified life is the period of time for 8606260145 860619 4 DR ADOCK 0500 j .

which satisfactory perfomance can be demonstrated for a specific set of service conditions. The qualification methods that can be used to determine the qualified life, including the effects of aging, are identified in IEEE Standard 323-1974. IEEE Standard 323-1974 provides guidance on aging based on an awareness that the ability of Class IE equipment to perfom its safety function may be affected by changes due to natural, operational, and environ-mental phenomena over time. The concept of aging was addressed explicitly for the first time in IEEE Standard 323-1974. The aging guidance therein reflects the requirement of IEEE Standard 279, which is the standard specifically mentioned in 16 CFR 50.55a(h). Confomance with IEEE Standard 323-1974 is a method, acceptable to the staff, of meeting the requirements of10CFR50.55a(h).

If it can be demonstrated that the qualified life exceeds the life of the generating station, then the specific qualified life need not be identified.

I In a practical sense, the intent of the life testing requirement of the generic letter would be satisfied by demonstrating that the qualified life of the breaker (for the tripping function) exceeds the expected use projected to the next refueling. Cycle testing by the various Owners Groups, although it does not consider the effects of aging, may provide evidence to support continued use of the RTBs for one additional refueling cycle, provided that the in(ividual breaker has not shown any sign of degradation in the licensee's Parametric Trend Monitoring Program. In this approach the actual qualified Itfe is not specifically identified, but only demonstrated to be adequate.

On-going life testing, as described in IEEE Standard 323-1974, is an acceptable alternative to formal life testing for the purpose of establishing a specific qualified life for RTBs. On-going life testing will demonstrate that the qualified life, though not specifically known, is longer (in terms of cycles and time) than the integrated service that will be accumulated through the next refueling interval. The description of an i

on-going qualification program should include the following:

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1. Definition of the number of demand; per unit of time, to which an RTB must respond, and the basis for the number of demands; i

2. Definition of relevant, end-of-life-related failures. (Note that random failures occurring during the constant hazard rate portion of the " bathtub curve" are not relevant to a life test); and

3. Definition of the action to be taken upon any failure.

2.2 Periodic Replacement Program If the qualified life of any component is less than the qualified life of the RTB, then the component should be replaced on an appropriately shorter time schedule. The criteria developed in support of this item include record keeping for service time and number of cycles for all breakers and short-lived devices or components.

3. EVALUATION 3.1 Evaluation of the Licensee Position on Item 4.2.3 The licensee is participating with the Westinghouse Owners Group on the life testing issue and will evaluate the recommendations issued following completion of the analysis. The licensee believes that trending of breaker j performance, an active maintenance program, and irl situ testing will provide a more realistic, and perhaps superior, representation of breaker operation '

than does life cycle testing and replacement.

The staff finds that the licensee did not connit to a life testing program.

The breakers' qualified life must be established based on actual testing of the breakers or an acceptable sample size. An on-going life testing would be an acceptable alternative to formal life testing, provided that the licensee program includes the three requirements mentioned under the Evaluation Criteria in this report.

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s- l 3.2 Evaluation of the Licensee's Position on Item 4.2.4 The licensee takes exception to replacement of components based strictly on life cycles. He believes that planned program of preventative maintenance and surveillance would be sufficient to detect breaker degradation and provides a high degree of confidence that the reactor trip breakers will perfom their safety function when required.

The staff finds the licensee position on this item unacceptable. The licensee should identify a replacement program for the breaker and breaker components. The program should consider data derived from the on-going life testing as well as the design life. If data from on-going qualification is used, the licensee should consider in-service failures, malfunctions during the periodic maintenance program and indication of degradation or failures from the measurements made for the trending of parameters. In addition, the licensee should specifically define how the on-going qualification results will be used to establish replacement cycles and times.

4. CONCLUSIONS 1 l

l Based on a review of the licensee responses, the staff finds the licensee l position on Item 4.2.3 and 4.2.4 of Generic Letter 83-28 to be unacceptable l

because it does not document the establishment of the qualified life of the 1 RTB and its replaceable components.

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