ML20203N533

SER Finding Util 831105 & 850806 Responses to Generic Ltr 83-28,Items 4.2.1 & 4.2.2 Re Reactor Trip Sys Reliability Acceptable

ML20203N533
Person / Time
Site:	Byron
Issue date:	04/28/1986
From:	NRC
To:
Shared Package
ML20203N525	List: ML20203N523 ML20203N533
References
GL-83-28, NUDOCS 8605050473
Download: ML20203N533 (6)

Text

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'O SAFETY EVALUATION REPORT BYRON STATION, UNITS 1 AND 2 REACTOR TRIP SYSTEM RELIABILITY ITEMS 4.2.1 AND 4.2.2 0F GENERIC LETTER 83-28

1. INTRODUCTION .

On July 8, 1983, the Nuclear Regulatory Commission (NRC) issued Generic letter (GL) 83-28). This letter addressed intermediate-term actions to be taken by licensee and applicants aimed at assuring that a comprehensive program of preventive maintenance and surveillance testing is implemented for the reactor trip breakers (RT8s) in pressurized water reactors. Item 4.2 required them 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 4.2.1 A planned program of periodic maintenance, including lubrication, housekeeping, and other items recommended by equipment supplier.

GL, Item 4.2.2 Trending of parameter acting operation and measured during testing to forecast degradation of operation.

8605050473 860428 PDR ADOCK05000gg4 P

7 Commonwealth Edison, the applicant for the Byron Station Units 1 and 2, submitted responses to the Generic letter on November 5,1983, and August 6, 1985. This report presents an evaluation of the adequacy of the applicant's rcsponses and its preventive maintenance and surveillance programs for RTBs.

2. EVALUATION CRITERIA 2.1 Periodic Maintenance Program The primary source for periodic maintenance program criteria is Westinghouse Maintenance Program Manual for DS-416 Reactor Trip Circuit Breakers, Rev. O. This document was prepared for the Westinghous Owners Group and is the breaker manufacturer's recommended maintenance program for the DS-416 breaker. It provides specific direction with regard to schedule, inspection and testing, cleaning, lubrication, corrective maintenance and recordkeeping. The document was reviewed to identify those items that contribut to breaker trip reliability consistent with the generic letter.

Those items identified for maintenance at six months intervals (or when 500 breaker operations have been counted, whichever comes first) that should be included in the applicant's RTB maintenance program are:

1. General inspection to include checking of breaker's cleanliness, all bolts and nuts, pole bases, arc chutes, insulating link, wiring and auxiliary switches;

2. Retaining rings inspection, including those on the undervoltage trip attachment (UVTA);

3. Arcing and main contacts inspection as specified by the Westinghouse Maintenance Manual;

4. UVTA check as specified by the Westinghouse Maintenance Marual, including replacement of UVTA if dropout voltage is greater than 60%

or less than 30% of rated UVTA coil voltage;

5. Shunt Trip Attachment (STA) check as specified by the Westinghouse Maintenance Manual;

6. l.ubrication as specified by the Westinghouse Maintenance Manual;

7. Functional check of the breaker's operation prior to returning it to service.

The applicant's RTB periodic maintenance should also include, on a refueling interval basis:

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1. Precleaning insulation resistance measurement and recording; l

2. RTB dusting and cleaning:

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3. Post-cleaning insulation resistance measurement and recording, as specified by the Westinghouse Maintenance Manual;

4. Inspection of main and secondary disconnecting contacts, bolt tightness, secondary wiring, mechanical parts, cell switches, instruments, relays and other panel mounted devices;

5. UVTA trip force and breaker load check as specified by the Westinghouse Maintenance Manual;

6. Measurement and recording of RTB response time for the undervoltage trip;

7. Functional test of the breaker prior to returning to service as specified by the Westinghouse Maintenance Manual.

2.2 Trending of Parameters Generic letter Item 4.2.2 specifies that the applicant's preventative maintenance and surveillance program is to include trending of parameters affecting operation and measured during testing to forecast degradation of operation. The parameters measured during the maintenance program described above which are applicable for trending are undervoltage trip attachment dropout voltage, trip force, response time for undervoltage trip and breaker

O insulation resistance. The staff position is that the above parameters are acceptable and recommended trending parameters to forecast breaker operation degradation or failure. If subsequent experience indicates that any of these parameters is not useful as a tool to anticipate failures or degradation, the licensee or applicant may, with justification and NRC approval, elect to remove that parameter from those to be tracked.

3. EVALUATION 3.1 Evaluation of the Applicant's Position on Item 4.2.1 The applicant states that its periodic maintenance program for RTB's includes thos items listed in Section 2.1 of this SER, but that all periodic maintenance is performed on a refueling outage basis, or 500 breaker operations, whichever comes first. The applicant follows the staff approved maintenance program outlined in the Westinghouse Manual for the 05-416 Reactor Trip Breaker, Revision 0, October 1984. The staff finds the applicant position on Item 4.2.1 to be acceptable.

3.2 Evaluation of the Applicant's Position on Item 4.2.2 The applicant has stated that it will perform a trend analysis on the four parameters listed in Section 2.2 of this SER. The applicant has identified the organization which will perform the trend analysis, how often

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e it will be performed and how the information derived from the analysis will be used to affect periodic maintenance. The staff finds the applicant position on Item 4.2.2 to be acceptable.

4. CONCI.USIONS Based on a review of the applicant responses, the staff finds the applicant's position in Items 4.2.1 and 4.2.2 of Generic l.etter 83-28 to be acceptable.

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