ML20211P932

Safety Evaluation Supporting Util Preventive Maint Program for Reactor Trip Breakers in Response to Generic Ltr 83-28 Items 4.1,4.2.1 & 4.2.2

ML20211P932
Person / Time
Site:	Wolf Creek
Issue date:	07/21/1986
From:	NRC
To:
Shared Package
ML20211P925	List: ML20211P919 ML20211P932
References
GL-83-28, TAC-57380, NUDOCS 8607230443
Download: ML20211P932 (6)

Text

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SAFETY EVALUATION REPORT T

WOLF CREEK GENERATING STATION REACTOR TRIP SYSTEM RELIABILITY ITEMS 4.1, 4.2.1 AND 4.2.2 0F GENERIC LETTER 83-28

1.

Introduction:

On July 8, 1983, the Nuclear Regulatory Comission (NRC) issued Generic Letter (G'

• 1-28. This letter addressed intermediate-term actions to be taken bl .... sees and applicants aimed at assuring that a comprehensive program or preventive maintenance and surveillance testing is implemented for the reactor trip breakers (RTBs) in pressurized water reactors. In particular, Item 4.1 of the letter required licensees and applicants to verify that all venoor recommended reactor trip breaker modifications have been implemented.

Item 4 2 required them 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 4.1 Review of all vendor-recommended reactor trip breaker modifications to verify that either: each modification has, in fact, been implemented, or a written evaluation of the technical reasons for not implementing a modification exists.

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

GL, Item 4.2.2 Trending of parameters affecting operation and measured during testing to forecast degradation of operation.

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i Kansas Gas and Electric Company, the licensee for Wolf Creek, responded to the Generic Letter on November 15, 1983, February 29, 1984 and July 17, 1985. This report presents an evaluation of the adequacy of the licensee's responses and of his preventive maintenance and surveillance 2

programs for RTBs.

r i 2. Evaluation Criteria j

2.1 Periodic Maintenance Program l

The primary source for periodic maintenance program criteria is Westing-house Maintenance Program Manual for DS-416 Reactor Trip Circuit Breakers,

! Rev. O. This document was prepared for the Westinghouse Owners Group and is the breaker manufacturer's recommended maintenance program for the DS-416 breaker. It provides specific direction with regard to schedule, inspection l and testing, cleaning, lubrication, corrective maintenance and record keeping, j 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 (or when 500 breaker operations have

been counted, whichever comes first) that should be included in the i licensee's RTB maintenance program are

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1. General inspection to include checking of breaker's cleanliness, all bolts and nuts, pole bases, arc chutes, insulating link, wiring and auxiliary switches; j 2. Retaining rings inspection, including those on the undervoltage trip attachment (UVTA);

3. Arcing and main contacts inspection as specified by the Westing- ,

house Maintenance Manual; i

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4. UVTA check as specified by the Westinghouse Maintenance Manual, including replacement of UVTA if dropout voltage is greater than 60% or less than 30% of rated UVTA coil voltage;

5. Shunt Trip Attachment (STA) check as specified by the Westinghouse Maintenance Manual;

6. Lubrication as specified by the Westinghouse Maintenance Manual; I 7. Functional check of the breaker's operation prior to returning it to service.

The licensee's RTB periodic maintenance should also include, on a refueling interval basis:

1. Pre-cleaning insulation resistance measurement and recording;

2. RTB dusting and cleaning;

3. Post-cleaning insulation resistance measurement and recording, as specified by the Westinghouse Maintenance Manual;

4. Inspection of main and secondary disconnecting contacts, bolt tightness, secondary wiring, mechanical parts, cell switches, instruments, relays and other panei mounted devices;

5. UVTA trip force and breaker load check as specified by the Westing-house Maintenance Manual; f

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6. Measurement and recording of RTB response time for the undervoltage trip;

7. Functional test of the breaker prior to returning to service as specified by the Westinghouse Maintenance Manual.

2.2 Trending of Parameters Generic Letter Item 4.2.2 specifies that the licensee's preventative l maintenance and surveillance program is to include trending of parameters affecting operation 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, response time for undervoltage trip and breaker insulation resistance. The staff position is that the above parameters are acceptable 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. Evaluation:

3.1 Evaluation of the Licensea's Position on Item 4.1 The licensee has confirmed that all vendor-recommended modifications have been completed. The staff finds the licensee position on Item 4.1 to be acceptable.

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t 3.2 Evaluation of the Licensee's~ Position on Item 4.2.1 i The licensee has confirmed that its periodic maintenance program will 7 include those items listed in Section 2.1 of this SER at the specified

! frequency. However, after several inspection periods, and if experience 3

warrants, the licensee plans to perfom all preventative maintenance during each refueling outage or after 500 RTR operations, whichever occurs first.

, The staff finds the licensee position on Item 4.2.1 to be acceptable.

Acceptance of the licensee's extended maintenance interval is based on the vendor recomendation that maintenance on RTBs located in mild environments ,

i should be perfomed at refueling intervals. The vendor recomendation that o* 'ocated in harsh environments or experiencing severe load conditions be l maintained more frequently is not applicable to these RTBs because of their location in a mild environment and reduced service duty at Wolf Creek (less than 200 RTB cycles annually).

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3.3 Evaluation of the Licensee's Position on Item 4.2.2 1

The licensee has stated that Wolf Creek will perform trend analysis on UVTA dropout voltage and breaker response time, and will record trip force and breaker insulation resistance. The applicant has identified the organization which will perform trend analysis, how often it will be

perfomed and how the information derived from the analysis will be used to I affect periodic maintenance. The staff finds the licensee position on Item 4.2.2 to be acceptable.

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' 4.

Conclusions:

i Based on a review of the licensee responses, the staff finds the licensee's position on Items 4.1, 4.2.1 and 4.2.2 of Generic Letter 83-28 to be I acceptable.

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g Mr. Glenn L. Koester Kansas Gas and Electric Company Wolf Creek Generating Station Unit No. 1 CC*

Mr. Nicholas A. Petrick Executive Director, SNUPPS Mr. Gary L. Haden. Director 5 Choke Cherry Road Research & Energy Analysis Rockville, Maryland 20850 Kansas Corporation Commission 4th Floor - State Office Building Topeka, Kansas Jay Silberg, Esq. 66612-1571 Shaw, Pittman, Potts & Trowbridge 1800 M Street, NW Regional Administrator, Region IV Washington, D.C. 20036 U.S. Nuclear Regulatory Comission Office of Executive Director for Operations Mr. Donald T. McPhee Vice President - Production 611 Ryan Plaza Drive, Suite 1000 Kansas City Power & Light Company Arlington, Texas 76011 1330 Baltimore Avenue Kansas City, Missouri 64141 Mr. Allan Mee Project Coordinator Chris R. Rogers, P.E. Kansas Electric Power Cooperative,Inc.

Manager Electric Department P. O. Box 4877 Public Service Comission Gage Center Station P. O. Box 360 Topeka, Kansas 66604 Jefferson City, Missouri 65102 Resident Inspector / Wolf Creek NPS Regional Administrator, Region III c/o U.S. Nuclear Regulatory Comission

' U.S. Nuclear Regulatory Commission P. O. Box 311 799 Roosevelt Road Burlington, Kansas 66893 Glen Ellyn, Illinois 60137 Mr. Brian Moline Brian P. Cassidy Regional Counsel Chief Legal Counsel Kansas Corporation Comission Region I Emergency, Management Agency Federal 4th Floor - State Office Building i t

J. W. McCormack P0CH Topeka, Kansas 66612-1571 Boston, Massachusetts 02109

- Senior Resident Inspector / Wolf Creek NPS y Mr. Robert Elliot, Chief Engineer c/o U.S. Nuclear Regulatory Comission Utilities Division P. O. Box 311 Kansas Corporation Comission Burlington, Kansas 66839 4th Floor - State Office Building Topeka, Kansas 66612-1571 Mr. Gerald Allen Public Health Physicist "

Bureau of Air Quality & Radiation Control Division of Environment Kansas Department of llealth and Environment Forbes Field Building 321 a Topeka, Kansas 66620 ,

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