ML20024H343
| ML20024H343 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 05/16/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20024H342 | List: |
| References | |
| NUDOCS 9106030019 | |
| Download: ML20024H343 (4) | |
Text
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UNITED STATES 8
g NUCLEAR REGULATORY COMMISSION o
l WASHINGTON, D, C. 20555
%, *....f ENCLOSURE,
SAFETY EVALVATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RE'!!SION TO THE TEST FREQUENCY FOR THE CABLE MEGGER TESTING NEW-HAMPSHIRE YANKEE r
SEABROOK STATION DOCKET NO. 50-443
1.0 INTRODUCTION
L By letter dated April 17, 1991, New Hampshire Yankee requested a revision to L
the test frequency currently applied to the megger testing of all safety and
'non-safety related cables initiated as part of the electrical cable and raceway separation criteric used at Seabrook Station.
The intent of this cable megger testing w : to detect any cable degradation which potentially could result in
. cable failures.
2.0 EVALVATION
'As part of the electrical and raceway separation criteria used at Seabrook Station, the licensee had committed to a surveillance test program comprising insulation resistance (megger) testing of safety and non-safety related cables.-
The intent of this cable megger testing is to detect any cable degradations which can. eventually result in cable failures. The frequency of= testing for safety and non-safety related cables currently specified at Seabrook, is-given in Attachment _1.
The licensee has' proposed to perform cable megger testing consistent with the testing frequency of the connected load. That is, the cabl.e testing will be performed as part of the connected load maintenance activity at a revised frequency (longer interval) outlined in Attachment-2.
This change leads to a more systematic and coordinated approach and is comen-surate with INPO Good Practice MA-316," Plant Predictive Maintenance."
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The maintenance program as originally envisioned would require approximately 420 loads to be tagged out of service for various electrical maintenance tasks during each refueling outage. Approximately 140 (33%) of these tagouts are required for cable testing only, with no other maintenance required for these particular loads. The licensee believes that such a large number of tagouts increases the probability of equipment unavailability during the outage. Any reduction in the number of unnecessary tagouts will enhance the maintenance program by making it more efficient. Additionally, the megger testing performed by the licensee to date has shown all megger values to be above the acceptance criteria and generally several times higher.
3.0 CONCLUSION
Based on the above, the staff concludes that the revised testing program will continue to provide adequate assurance that cables at the Seabrook Station are capable of performing their design function, tie believe that the new proposed surveillance frequencies are adequate to detect any potential cable degradation without unnecessarily increasing the probability of equipment unavailability ouring the testing period. The proposed schedule for cable testing at Seabroek Station is in agreement with testing frequency recommended by ANSI-flFPA-708, 1977. Therefore, the staff finds tne revised schedule to be acceptable.
i Principal Contributor i
- 0. Chopra
~
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ATTACHMENT 1 CURRENT TEST FREQUEt;CY FOR CABLE MEGGER TESTING MOTORS Feeder cables to all safety and non-safety related icotors 50HP and larger are tested every refueling.
Feeder cables to all safety related motors smaller than 50HP are tested every refueling.
Feeder cables to all non-safety related motors smaller than 50HP are tested every 5th refueling.
l U; LIT SUBSTATIONS Feeder cables to safety and non-safety related unit substations are tested every 3rd refueling.
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MOTOR CONTROL CENTERS Feeder cables to safety related Motor Control Centers (ftCC) are tested i
every 3rd refueling.
I i
Feeder cables to non-safety related Motor Control Centers are tested L
every 5th refueling.
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MISCELLANEOUS I
Feeder cables to miscellaneous loads (except Motor Control Centers) fed from Unit Substations are tested at an interval not to exceed every 5th refueling.
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ATTACHMENT 2
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PROPOSED TEST FREQUEllCY FOR CABLE MEGGER TESTING MOTORS 4.16 KY and 13.8 KV safety and non-safety related motors and their feeder cables:
Every other refuel or every 3 years 480 VAC safety related motors and their feeder cables:
Every other refuel or every 3 years 480 VAC non-safety related motors 50 HP and their feeder cables:
Every other refuel or every 3 years 480 VAC safety reloted motors and their feeder cables:
Every third refuel er every 5 years 125 VDC non-safety related motors and their feeder cables:
Every third refuel or every 5 years MOTOR-0PERATED VALVES s
Safety related MOVs and their feeder cables:
Every other refuel or every 3 years Non-safety related MOVs and their feeder cables:
Every third refuel or every 5 years UNIT SUBSTATIONS Feeder cables to safety and non-safety related unit substation:
Every third refuel or every 5 years l