ML20128G028

Safety Evaluation Supporting Util Responses to Generic Ltr 83-28 Re Preventive Maint & Surveillance Testing for Reactor Trip Breakers in PWRs

ML20128G028
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	06/20/1985
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20128G017	List: ML20128G013 ML20128G028
References
GL-83-28, NUDOCS 8507090012
Download: ML20128G028 (4)

Text

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SAFETY EVALUATION BY 9P THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO OPERATION OF ZION NUCLEAR POWER STATION UNIT NOS. 1 AND 2 COMMONWEALTH EDISON COMPANY DOCKET NOS. 50-295 AND 50-304 ITEMS 4.2.1 AND 4.2.2 0F GENERIC LETTER 83-28

1. INTRODUCT, ION 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 licensees and applicants aimed at assuring that a comprehensive program of preventive maintenance and surveillance testing is imp.lemented for the reactor trip breakers (RTBs) in pressurized water te 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 4.2.1 A planned program of periodic mSintenance, including

. ,1ubrication, housekeeping, and other items recommended by'the equipment supplier.

GL, Item 4.2.2 Trending of parameters affecting operation and measured during testing to forecast degradation of operation.

Commonwealth Edison, the licensee for Zion 1 and 2, submitted reponses to the Generic Letter on November 5, 1983, February 29, 1984, and March 11, 1985. This report presents an evaluation of the adequacy of those ,

responses and of the licensee's preventive maintenance and surveillance

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programs'for RT8's.

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2. EVALUATION CRITERIA .

2.1 Periodic Maintenance Program -- -

The primary source for periodic maintenance program criteria is f

Westinghouse Maintenance Program for 08-50 Reactor Trip Switchgear, Rev. O. This document is the breaker manufacturer's recommended j maintenance program for the DB-50 breaker and provides specific direction with regard to schedule, inspection and testing, cleaning, lubrication,

corrective maintenance and record keeping. The document was reviewed to' identify those items that contribute to breaker trip reliability consistent i with the generic letter. Those items identified for maintenance at six '

month intervals that should be included in the licensee's RTB maintenance program are: .

I 1. Verification of trip bar freedom -

2. Verification of operating mechanism alignment and freedom

3. Retaining ring verification

4. Verification of nut and bolt tightness i

5. Verification of pole bases physical condition

6. Verificatjon of arcing and main contacts physical condition ,

7. Verification of insulating link's physical condition

8. Verification of wiring insulation and termination physical condition

9. Verification of are chute physical condition

10. Verification of breaker cleanliness

11. Undervoltage Trip Attachment (UVTA) dropout voltage test and lubrication

12. Shunt Trip Attachment (STA) operation verification

13. Verification of operation of auxiliary switches 4

14. Inspection cf positioning lever condition -

j 15. Functional test of the breaker prior to returning it to service.

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- The licensee's RTB periodic maintenance should also include, on a -

refueling interval basis:

16. Verificaticn of cell interlock operation

17. Examination and cleaning of breaker enclosure

18. Measurement of trip force required

19. Functional test of the breaker prior to returning it to service

20. Breaker response time for undervoltage trip.

All of the items listed above are recommended by the manufacturer .

except Item 20. This item is the breaker trip response time measurement which is implied by the IEEE Standard 279-1971. '

2.2 Trending of Parameters Generic Letter Item 4.2.2 specifies that the Licensee'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 attachmentdropoutyoltage,tripforce,andbreakerresponsetimefor undervoltage trip. 'The staff position is that-the above three parameters ~

in addition to the breaker insulation resistance are acceptable and recommended trending parameters to forecast breaker operatio'n 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 may, with justification and NRC approval, elect to remove that parameter from those to be tracked.

3. EVALUATION 3.1 Evaluation of the Licensee Position on Item 4.2.1 The licensee states that his preventative maintenance program for RTB's is being revised and by September 1, 1985, will contain all the elements detailed in Section 2.1 of this SER; however, the licensee 3

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. l performs maintenance on the breakers at refueling . intervals. The licensee -

states that the extended interval is justified based on the maintenance

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history of the breakers and the Zion estimate of 50 breaker actuations per -

fuel cycle. .The staff finds the licensee position on Item 4.2.1 to be acceptable.

3.2 Evaluation of the Licensee's Position on Item 4.2.2 The licensee has committed to performance of trend analysis of trip, force, breaker response time, undervoltage trip dropout voltage and insulation resistance. The licensee has identified the organization which will perform trend analysis, how often it will be performed and how the ~

information derived from the analysis will be used to affect periodic maintenance. The staff finds the licensee position on Item 4.2.2 to be acceptable. .

4. CONCLUSIONS Based on a review of the licensee responses, the staff f'inds the licensee positions on Items 4.2.1 and 4.2.2 of Generic Letter 83-28 to be acceptable. .

Principal Contributor:

N. Romney .

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