ML17321A505
| ML17321A505 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 03/29/1985 |
| From: | Alexich M INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| AEP:NRC:08386, AEP:NRC:8386, AEP:NRC:838G, GL-83-28, NUDOCS 8504030214 | |
| Download: ML17321A505 (8) | |
Text
REOULATOROINFORNATION DISTRISUTION ITEN (RIDS)
ACCESSION NBR ~ 8504030214 DOC ~ DATE 85/03/29 NOTARIZED ~
NO, DOC K E~TA ¹ FACIL;50 315 Donald C ~
Cook Nuclear Pawer Pl anti Un) t li Indiana 8
05000315 50-316 Donald O,
Cook Nucl ear Power Pl anti Uni t 2i Indiana 8
05000316 AUTH ~ NAME AUTHOR Al FILIATION ALEXICHEM,P, Indiana 8 Michigan Electric Co, RECIP ~ NAME>
RECIPIENT AFF IL'IATION DENTONiH.Rs Office) of Nuclear Reactor Regulationi Director 1
SUBJECT:
Responds to 841114 r equest for. addi info.re-Generic Ltf" 83 28iItems 4 ~ 2',1 8 4.2.2;Response.
re I.tern 4,3 <<submitted on 841221.,plantA procedures to be revised to incpr porate'.Rev 0
to 831014 "Maint Program for DB 50 Reactor Trip switchgear>~I'ISTRIBUTION CODE'!
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INDIANA 8 NICHIGAN ELECTRIC CON PAN Y P.O. BOX 16631 COLUMBUS, OHIO 43216 March 29, 1985 AEP:NRC:0838G Donald C. Cook Nuclear Plant Unit Nos.
1 and 2
Docket Nos. 50-315, 50-316 License Nos.
DPR-58, DPR-74 GENERIC LETTER 83-28
RESPONSE
INFORMATION REQUEST ON ITEMS 4.2.1 and 4.2.2 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Mr. Denton:
This letter responds to your staff's November 14, 1984 request for additional information concerning, Generic Letter 83-28, Items 4.2.1 and 4.2.2.
A response concerning Item 4.3 was submitted in letter AEP:NRC:0838E on December 21, 1984.
Item 4.2.1 The Westinghouse Owners Group (WOG) recommended maintenance program titled "Maintenance Program for DB-50 Reactor Trip Switchgear, Rev. 0:
10/14/83,"
(WOG Maintenance Program DB-50) by E. Reed, N. E. Stoyanoff, and E.
Vogeding, has been approved for use at the D. C. Cook Plant with some modifications as explained below.
This modified maintenance program has been transmitted to the plant for incorporation into the plant maintenance procedures.
The plant procedures will be revised accordingly, and the revised procedures will be used during the 1985 Unit 1 refueling outage.
o The WOG Maintenance Program DB-50 has been revised to require all of the maintenance steps to be performed at each refueling outage or after 200 close-trip cycles of the circuit breaker since the last maintenance activity.
In addition, actual voltage acceptance values for the 250-volt shunt trip attachment and the 48-volt undervoltage trip attachment have been provided instead of the percentages used in the WOG 'Maintenance Program DB-50.
o The WOG Maintenance Program DB-50 recommended maintenance interval has been revised from a six months cycle to refueling outages for activities 1 through 17.
These circuit breakers have been maintained at refueling outages using the original Westinghouse instruction books and applicable technical bulletins as updated.
These circuit breakers have never failed to trip when required either for surveillance testing or when actuated by the reactor protection system.
The circuit breakers are subjected to light 85040$ 02i4 850329 PDR ADQCK 05000315 I'
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Mr. Harold R. Denton AEP:NRC:0838G electrical service and are. located in a clean and dry environment.
An evaluation of the lightduty, past history of adequate maintenance and non-hostile surroundings,,together with a past history of no failures to'rip, warrants the 'limitation of the maintenance interval to the refueling outage.
The potential for human error always exists during the removal, teardown, inspection, reassembly, and reinstallation of any component or device.
An error such as the failure'to properly torque certain bolts during the'reassembly process could escape detection during post-maintenance operability tests, but cause a
failure later during an actual demand.
In addition, we believe the wear and tear on the breaker components will be increased by increasing the maintenance frequency.
This wear and tear, because of too frequent, maintenance, could exceed the wear incurred through normal usage and surveillance testing.
In light of these two
- factors, we believe that increasing the maintenance frequency will decrease the strived for reliability and reduce, rather than
- enhance, the safety function of the breakers.
Instead of increasing the maintenance frequency, we propose to trend the response time of the Shunt Trip features when they are tested periodically, in the monthly and startup surveillance test procedures.
The trending analysis will be performed at each surveillance interval in accordance with criteria provided by the cognizant Electrical Engineer.
Unacceptable performance will be reviewed and corrective action taken using the procedure outlined in 4.2.2 below.
o The 15 items listed in the NRC letter will be included in the plant maintenance procedure but will also be revised from a six months cycle to refueling outages.
Items 1, 2, 3, and 5 listed for the refueling outage maintenance interval will be included in the plant maintenance procedure.
The connections which will permit measuring the response time for the undervoltage trip (Item 4) will be installed as part of the shunt trip attachment modification.
The plant specific design for this was submitted to the NRC in letter AEP:NRC:0838E dated December 21,
- 1984, and was approved.
The plant procedures will be revised to include the measurement of the undervoltage trip time.
Item 4.2.2 Recording and trending the undervoltage trip device minimum trip voltage (dropout voltage) is required and is described in the WOG Maintenance Program DB-50.
Trending this parameter will allow compliance with the maintenance program and will use the recommended acceptance and corrective action.
This trending activity will be implemented at the same time the revised procedure is implemented.
Trending will begin with the first refueling outage that the shunt trip attachment modification is installed.
Additional prescribed trending is indicated below.
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4 Mr. Harold R. Denton AEP:NRC:0838G o
The trip force will be measured in accordance with the referenced procedure and will be recorded and trended; the breaker response time for undervoltage trip will be measured, recorded and trended; and the breaker insulation resistance will be measured, recorded and trended.
o The trending analysis will be performed by members of the plant staff using criteria in the WOG Maintenance Program DB-50.
The acceptance criteria will be provided by the Cognizant Electrical Engineer if it is not provided for in the WOG Maintenance Program DB-50.
The trending program analysis will be conducted at each refueling outage coincident, with the breaker maintenance.
The Cognizant Electrical Engineer will evaluate unacceptable variations in parameters, outside the acceptance criteria.
After this evaluation, the Cognizant Electrical Engineer will initiate a review of the maintenance procedure, replacement of the degraded parts, and evaluation of maintenance frequency or other steps as required to restore the circuit, breakers to a condition of continued reliability.
This document has been prepared following Corporate procedures which incorporate a reasonable set of'controls to insure its accuracy and completeness prior to signature by the undersigned.
Very truly yours, M. P. Ale ich Vice President cc:
John E. Dolan W.
G. Smith, Jr. - Bridgman R. C. Callen G. Bruchmann G. Charnoff NRC Resident Inspector - Bridgman
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