ML16341D271
| ML16341D271 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 06/24/1985 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML16341D270 | List: |
| References | |
| GL-83-28, NUDOCS 8507010285 | |
| Download: ML16341D271 (10) | |
Text
SAFETY EVALUATION GENERIC LETTER 83-28, ITEMS 4.2.1 AND 4.2.2 REACTOR TRIP SYSTEM RELIABILITY Enclosure PREVENTIVE MAINTENANCE PROGRAM FOR REACTOR TRIP BREAKERS/
MAINTENANCE AND TRENDING DIABLO CANYON UNITS 1
AND 2 1.
INTRODUCTION On July 8, 1983, the Nuclear Regulatory Conmission (NRC) issued Generic Letter 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 licensees and applicants to submit a description of their preventive maintenance and surveillance program to ensure reliable reactor trip breaker operation.
T'e description of the submitted program was to include the following:
Item 4.2. 1 A planned program of periodic maintenance, including lubrication, housekeeping, and other items recommended by the equipment supplier.
Item 4.2.2 Trending of parameters affecting operation and measured during testing to forecast degradation of operation.
C I'
Pacific Gas and Electric Company (PGRE), the licensee for Diablo Canyon Units 1 and 2, submitted responses to these items on November 7, 1983, December 20,
- 1983, May 24,
- 1984, and February 21, 1985.
This report presents the staff evaluation of the adequacy of those responses and of the licensee's preventive maintenance and surveillance programs for RTBs.
2.
EVALUATION CRITERIA
- 2. 1 Periodic Maintenance Program The primary source for the periodic maintenance program criteria is the "Westinghouse Maintenance Program for DB-50 Reactor Trip Switchgear, Rev. 0,"
dated October 13, 1983.
This document is the maintenance program recommended by the manufacturer 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 Generic Letter 83-28.
Those items identified in the document for maintenance at six month intervals that should be included in the RTB maintenance program of licensees 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
i'ei ification of insulating link physical condition 8.
verification of wiring insulation and termination physical condition 9.
verification nf arc chute physical condition 10.
verification of breaker cleanliness Il.
undervoltage tlip attachment (UVTA) dropout voltage test and lubricatior 12.
shunt trip attachment (STA) operation verification 13 0 verification of operation of auxiliary switches 14.
inspection of positioning lever condition 15.
functional test of the hreaker prior to returning it to service.
The PTP periodic maintenance by the licensees should also include, on a
refueling interval basis:
16.
verification of ce~ 1 interlock operation 17.
examination and cleaning of breaker enclosure 18.
measurement of trip force required 19, functional test of the breaker prior tn returning it to service 20.
breaker response time for undervoltage trip.
All of the items iisted above are recommended by the manufacturer except Item Ã.
This item is the breaker trip response time measurement which is implied by the IEE Standard 279-1971.
t
2.2 Trending of Parameters Generic Letter 83-28, Item 4.2.2, specifies that the preventive maintenance and surveillance programs of the licensees 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, a licensee may, with justification and NRC approval, elect to remove that parameter from those to be tracked.
3.
EVALUATION 3.1 Evaluation of PG&E Position on Item 4.2.1 PGSE has stated that the Diablo Canyon preventive maintenance program for RTB's is being revised and will contain all the elements listed in Section
- 2. 1 above with the maintenance to be performed initially at six-month intervals.
The staff finds the licensee position on Item 4.2.1 to be acceptable.
3.2 Evaluation of the PGSE Position on Item 4.2.2 PGRE has committed to revise the Diablo Canyon trend analysis program for the RTB's to include performance of trend analysis of trip force, breaker response time, undervoltage trip dropout voltage and insulation resistance.
PGSE 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 PG&E position on Item 4.2.2 acceptable.
4.
CONCLUSIONS Based on a review of the PGSE responses, the staff finds the licensee position on Items 4.2. 1 and 4.4.2 of Generic Letter 83-28 acceptable.
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