ML20134N002

Safety Evaluation Re Util 831105,850118 & 0719 Responses to Generic Ltr 83-28,Items 4.2.1 & 4.2.2 Concerning Reactor Trip Sys Reliability.Licensee Positions Acceptable

ML20134N002
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	08/27/1985
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20134M987	List: ML20134M984 ML20134N002
References
GL-83-28, TAC-53159, NUDOCS 8509040372
Download: ML20134N002 (4)

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g UNITED STATES NUCLEAR REGULATORY COMMISSION G j WASHINGTON. D C. 20555

%,o..,*j SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION PORTLAND GENERAL ELECTRIC COMPANY TROJAN NUCLEAR PLANT DOCKET NO. 50-344 REACTOR TRIP SY5ftM RELIABILITY ITEMS 4.2.1 AND 4.2.2 0F GENERIC LtiltR 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 i h

,to be taken by licensees and applicants aimed at assur ng t at 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 4.2.1 A planned program of periodic maintenance, including lubrication, housekeeping, and other items recommendeo by the equipment supplier.

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

Portland General Electric Company, the licensee for Trojan, submitted responses to the Generic Letter on November 5,1983, January 18,1985, and July 19, 1985. This report represents an evaluation of the adequacy of those responses and of the licensee's preventative maintenance and surveillance programs for RTBs.

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2. EVALUATION CRITERIA 2.1 Periodic Maintenance program

- The primary source for periodic maintenance program criteria is Westinghouse Maintenance Program for 08-50 Reactor Trio Switchgear, Rev. O. This document is the breaker manufacturer's recommended caintenance program for the 08-50 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 with the generic letter. Those items identified for maintenance at 6 conth intervals that should be included in the licensee's RTB maintenance program are:

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

5. Verification of pole bases physical condition

6. Verification 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

14. Inspection of positioning lever condition

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. Verification of cell interlock operation  ;

17. Examination and cleanini of breaker enclosure

18. Measurement of trip force required

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

20. Breaker response time for undervoltage trip.

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4 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.

4 i 2.2 Trending of parameters j

l Generic Letter Item 4.2.2 specifies that the licensee's preventative j 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 l attachment dropout voltage, trip force, and breaker response time for undervoltage trip. The staff position is that the above three parameters j j j in addition to the breaker insulation resistance are acceptable and .

j recommended trending parameters to forecast ' breaker operation degradation o

or failure. If subsequent experience indicates that any of these .

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parameters is not useful as a tool to anticipate failures or degradation, i

the licensee may, with justification and NRC approval, elect to remove that parameter from those to be tracked. ,

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! 3. ~ EVALUATION l 3.1 ' Evaluation of the Licensee Position on Item 4.2.1 J

! The licensee states that his revised preventative maintenance program '-

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for RTB's contains all the elements detailed in Section 2.1 of this SE l ,

however, the licensee performs maintenance'on the breakers at annual l

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intervals. The licensee states that Trojan has yet to experience any difficulties with the DB-50 reactor trip breakers and that the improvements in maintenance provided by their recently revised procedure is expected to maintain their reliable operation. The referenced Westinghouse maintenance program states that the semi-annual activities might be extended to a maximum of 12 months if experience shows This to be sufficient, provided that 20'0 breaker cycles are not exceeded during this interval. By letter dated July 19, 1985, the licensee provided infonnation concerning the expected number of breaker cycles per reactor trip breaker per year. Because the expected number of cycles, 77, is within the recorrmended Westinghouse limit,  ;

the ' staff finds the licensee's position on the mafntenance frequency 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 iderytified 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 upon the review of the licensee responses, the staff finds the licensee positions on Item 4.2.1 and Item 4.2.2 acceptable.

Principal Contributor:  ?

N. Romney, DE ,

Date: August 27, 1985

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