ML20195J089

Safety Evaluation Accepting Program for Plant in Response to Items 4.2.1 & 4.2.2 of Generic Ltr 83-28 Re Reactor Trip Sys Reliability

ML20195J089
Person / Time
Site:	Sequoyah
Issue date:	11/28/1988
From:	NRC OFFICE OF SPECIAL PROJECTS
To:
Shared Package
ML20195J086	List: ML20195J082 ML20195J089
References
GL-83-28, NUDOCS 8812010245
Download: ML20195J089 (5)

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SAFETY EVALUATION REPORT SEQUOYAH NUCLEAR PLANT. UNIT 5 1 AND 2  !

REACTOR TRIP 5YSTEM RELIABILITY l ITEMS 4.2.1 AND 4.2.2 0F GEhERIC LETTER 03-28 [

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!NTRODUCTION

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On July 8,1983, the Nuclear Regulatory Comission (NRC) issued Generic letter f (GL) 83 28. This letter addressed interrediate-tern actions to be taken by  :

licensees and applicants air.ec at assuring that a comprehensive program of pre. I ventive maintenance and surveillance testing is implemented for the reactor trip  !

I breakers (RTBs) in pressuri:ed water reactors, In particular. Item 4.2 of the i letter required the licensees and applicants to submit a description of their j preventive maintenance and surveillance program to ensure reliable reactor trip breaker operation. The description of the submitted program was to include the  !

4 following:

GL, Item 4.2.1 A planned program of periodic maintenance, including lubrication, housekeeping, and other items recomended j by the equipment supplier.

GL, :en 4.2.2 Trending of parameters affecting cperation and reasured j during testing to forecast degradation of operation. {

t Ter.nessee Valley Autacrity, the licensee for Sequoyah 1 and 2 submitted a response {

to the Generic Letter or October 19, IN8. This was followed by a Telecen j response on November 2. 1988. This repert presents an evaluation of the adequacy {

rf tho'e responses and of the licensee's preventive traintenance and serveil. lance l t

orc; rams for RTBs.

EVALUATION CRITERIA Periodic Maintenance Prograg The prirary source reviewed by the NRC staff for deveicring the per' odic mainte-cance progran criteria was L'estinghuuse Mairter.ance Pregrara #cr Oh-F0 Feactor J

trip Switchgear. Pev. O. This decurent was the .5reaker manuf acturer's recc t erded

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s maintenance program for the 08-50 breaker and provided specific direction with regard to schedule, inspection and testing, cleaning, lubrication, corrective maintenance and rec +J kecting. The document was reviewed to identify those itams that contributi ' .iker trip reliability consistent with the generic letter. Those items ide. J for maintenan..e at six month intervals to be included in the licenset .8 maintenance program aret j

1. Verification of trip bar freedom

2. Verification of operating mechanism alignment and freedom

3. Retaining ring verification

4. Verificetion of nut and bolt tightness

5. Verification of pole bases physical conditita

6. Verificatinn 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 'reaker o cleanliness

11. Underioltage Tr'p Attachment (UVTA) dropout voltage test and lubrication.

. Shunt Trip Attachment (aTA) 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 The items identified for maintenance on a refueling interval basis are:

16. Verification of cell interlock operation

17. Examination and cleaning of breaker enclosure

18. l'easurerrent of trip force required

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

20. Breaker response tire for undervoltage trip

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': All of the items listed above were reconrended by the manufacturer except Item 20. This item is the breaker trip response time measurement which is implied by the IEEE Standard 279-1971.

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, 6nd 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 *' .ove that parameter from those to be tracked.

EVALUATION The licensee noted in their October 10, 1988 submittal that performance of maintenance at 6 conth intervals was based on a Westinghouse mainten3nce pro-gram manual dated October 14, 1983. Subsequently, Westinghouse issued a revised <

maintenance program manual MPM-WOGRTSDB50-01 for Westinghouse type 08-50 reactor trip breakers (RTBs) which specifies a maintenance period not to exceed 18 months.

We have found the 18 month perind to be acceptable for other licensees provided that the breakers are not cycled more than 200 times during the 18 month period.

By telecon of November 2,1988, the lice ce estimated that the number of PTB cycles during the 10 mnnth period woul less than 50. Based on this informa-tion, we find that the 18 month intervai + maintenance cycles is acceptable.

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P The licensee states that the 20 RTB maintenante items listed above are included in their naintenance procedures MI-10.9.1 and MI-10.9.2 for the RTBs and bypass ,

tripbreaker(BTBs),respectively. In addition, provisions are included to re-place the undervoltage trip attachment (UVTA) and shunt trip attachment (STA) if either has been in service for 60 months or more (at the time of maintenarce) or if the test data obtained during maintenance cannot be brought within the acceptance criterie, for either the UVTA or STA. Based on these provisions, ar.d the fact that the RTBs would normally be cycled less than 200 times between maintenance pericds, we find the licensee's progran for periodic maintenance of the RTBs to be acceptable.

F Turning now to the trending program for the RTBs, the licensee states that the following items are recorded during maintenance and used in the trending program.

1. STA installation date (replace if installation timed 50 months)

2. UVTA installation date (replace if installation time l 60 months)

3. UVTA dropout voltage (before lubrication and after lubrication)

4. Trip bar trip force

5. UVTA coil resistance

6. UVTA insulatior resistance

7. Breaker actuation response time ('for undervoltage trip)*

C. Breaker insulation resistance (phase-to-phase and phase-to-frame) tiote. RTBs only, not BTBs The above data is reviewed by the Electric &1 Maintenance Group engineer, and if an unacceptable trend develops, action is taken to resolve tha problem and obtain acceptable results to ensure proper breaker operation. Based on the above program, we find the licensee's data recording and trending progran for the RTBs to be acceptable.

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SUMMARY

AND CONCLUSION The licensee has committed to a comprehensive program for periodic maintenance, testing and data tren;ing for the RTBs at the Sequoyah Nuclear Plant. We find this program consistent with the NRC staff's position of item 4.2 (Parts 1  ; .

and 2) of Generic letter 83-28 and therefore to be acceptable.

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