ML20128B438

Safety Evaluation of Util 831108,840316 & 850201 Responses to Items 4.2.1 & 4.2.2 of Generic Ltr 83-28 Re Reactor Trip Sys Reliability.Response Acceptable

ML20128B438
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	07/01/1985
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20128B388	List: ML20128B387 ML20128B438
References
GL-83-28, NUDOCS 8507030228
Download: ML20128B438 (5)

Text

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION HADDAM NECK PLANT  ;

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 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 reliabla 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 the equipment supplier.

GL, Item 4.'2.2 Trending of parameters affecting operation and measured during testing to forecast degradation of operation.

Connecticut Yankee Atomic Power Company, the licensee for the Haddam Neck Plant, submitted responses to the Generic Letter on November 8, 1983, March 16, 1984, and February 1,1985. This report presents an evaluation of the adequacy of those responses and of the licensee's preventive maintenance and surveilla'nce programs for RTBs.

8507030228 850701 PDR ADOCK 05000213 P PDR 1

9 2. EVALUATION CRITERIA

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2.1 Periodic Maintenance Program The primary source for periodic maintenance program criteria is Westinghouse Maintenance Program for 08-50 Reactor Trip Switchgear, Rev. O. This document is the breaker manufacturer's recommended 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 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:

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 conditio.n

8. Verification of wiring insulation and termination physical condition

, , 9. Verification of arc chute physical condition

10. Verification of breaker cleanliness i

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 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 -

attachment dropout voltage, trip force, and breaker response time for 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 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 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 April 26, 1985, will contain all but two of the elements detailed in Section 2.1 of this SER. The two items not 3

I l l included are inspection of the positioning lever condition and verification of cell interlock operation. The licensee justifies omission of inspection of the positioning lever and verification of cell interlock operation on the basis that the Haddam Neck RTBs are bolt-in, rather than rack-out, breakers, and that these items are not applicable to bolt-in breakers. The staff concurs. The fact that the breakers are bolted in also necessitates the use of a functional test procedures which differs from the one described by Westinghouse. The staff finds this acceptable.

The licensee performs those items of maintenance recommended for six month intervals at six month intervals when and if the plant is shut down for 4 other reasons; otherwise, he performs them at refueling intervals. The licensee justifies his variation from the recommended six month interval for the majority of the items in Section 2.1 of this SER on the basis that the Haddam Neck reactor trip system was not designed to permit on-line t'esting, and so does r.ot have bypass breakers. Item 4.5.2 of Generic Letter 83-28 requires the licensee to provide on-line testing capability or to provide justification for its continued omission. The Instrumentation and Control Systems Branch (ICSB) is reviewing the licensee response to item 4.5.2.

Preliminary review by ICSB has indicated that Haddam Neck will not be required to provide on line testing of reactor tr'- breakers. Therefore the maintenance interval is 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. T,he staff finds the licensee position on Item 4.2.2 to be acceptable.

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

Dated: July 1, 1985 O

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