ML18031B337
| ML18031B337 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 01/20/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18031B336 | List: |
| References | |
| GL-83-28, NUDOCS 8702030488 | |
| Download: ML18031B337 (7) | |
Text
SAFETY EVALUATION REPORT H.
B.
ROBINSON STEAM ELECTRIC PLANT:;UNIT 2 REACTOR TRIP SYSTEM RELIABILITY ITEMS 4.2. 1 AND 4.2.2 OF GENERIC LETTER 83-28
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INTRODUCTION On July 8, 1983, the Nuclear Regulatory Commission (NRC) issued
~C Generic Letter (GL) 83-28, This letter addressed inteipediate-term actions to be taken by licensees and applicants aimed at assuring that a
comprehensive program of preventive maintenance and sur0ei llance testijg 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 recommended by the equipment supplier.
GL, Item 4.2.2 Trending of parameters affecting operation and measured during testing to forecast degradation of operation.
Carolina Power and Light Company, the licensee for H. B. Robinson Unit 2, submitted responses to the Generic Letter on November 4,
- 1983, March 7,
- 1985, and June 13, 1986.
This report presents an evaluation of the adequacy of those responses and of the licensee's preventive maintenance and surveillance programs for RTBs.
8702030488 8701ZO i"
PDR ADOCK 0500026l p
- 2. 1 Periodic Maintenance Pro ram The primary source for periodic maintenance program criteria is Mestin house Maintenance Pro ram for DB-50 Reactor Tri Switch ear, Rev.
0.
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:
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 arc 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
refuelina 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.
'll 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 Trendin 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.
EVAI UATION 3.1 Evaluation of the Licensee Position on Item 4.2.1 The licensee states that his preventative maintenance program has been modified to include each of the items detailed in Section 2.1 of this'SER.
e The licensee has taken exception to the recommended
- mains, nance frequency; Robinson 2 performs those parts of the program recommended for a six month interval on an annual. basis.
THe licensee justifies extension 'of the six month interval to 12 months based on operational usage and experience at Robinson.
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 200 breaker cycles are not exceeded during this interval.
The licensee estimates that 100 RTB trips are typically experienced during the interval.
The staff finds the licensee's position on the maintenance frequency acceptable.
3.2 Evaluation of the Licensee's Position on Item 4.2.2 The licensee has committed to perform trend analysis on all the parameters identified in Section 2.2 of this SER.
The staff finds the licensee parametric trending program adequate, and the licensee's position on Item 4.2.2 acceptable.
4.
CONCLUSIONS Based on the review of the licensee responses, the staff finds the licensee positions on Items 4.2. 1 and 4.2.2 acceptable.