ML20076M237

Forwards Util 830603 Deficiency Rept Re Westinghouse Model DS-416 Reactor Trip Breaker,For Info.New & Redesigned Undervoltage Attachments in All DS-416 Switchgear Will Be Installed & Tested Before Fuel Load.Related Correspondence

ML20076M237
Person / Time
Site:	Byron
Issue date:	07/12/1983
From:	Bloom J ISHAM, LINCOLN & BEALE
To:	Callihan A, Cole R, Smith I Atomic Safety and Licensing Board Panel
References
NUDOCS 8307200201
Download: ML20076M237 (5)

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ISHAM, LINCOLN & BEALEQ tCi N COUNSELORS AT uW I k* " 4 THREE FiRST NATONAL PLAZA lG JOL 1g $B3.2 Y CHICAGO stuNorsacte gq@

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• • / i6J m mim July 12, 1983 Ivan W. Smith Dr. Richard F. Cole Administrative Judge,,and Administrative Judge Chairman Atomic Safety and Licensing Atomic Safety and Licensing Board Board U.S. Nuclear Regulatory U.S. Nuclear Regulatory Commission Commission Washington, D.C. 20555 Washington, D.C. 20555 Dr. A. Dixon Callihan Administrative Judge Attomic Safety and Licensing Board c/o Union Carbide Corporation P.O. Box Y Oak Ridge, Tennessee 37830 Re: In the Matter of Commonwealth Edison Company (Byron Nuclear Power Station, Units 1 and 2)

Docket Nos. 50-454 and 50-455 Gentlemen:

In accordance with the disclosure requirements of the McGuire case,* I am enclosing a letter dated June 3, 1983 from E. Dpuglas Swartz, the Nuclear Licensing Administrator for Commonwealth Edison Company to James G. Keppler, the NRC's Region III Regional Administrator. The letter may be relevant to the presentations made at the licensing hearings on April 21, 1983 concerning Byron's automatic reactor scram (trip breaker) system. The purpose of this filing is to j . apprise the Licensin,g Board of additional information, developed after the presentations, involving the DS-416 reactor trip breaker, manufactured by.the Westinghouse Electric Corporation (" Westinghouse").

i Duke Power Company (William B. McGuire Nuclear Station,'

i Units 1 and 2), ALAB-143, 6 AEC 623, 625 (1973).

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?* July 12, 1983

-r- c.. .Ivan W. Smith

-E .55.,_ Dr. Richard F. Cole

.Dr' . A. Dixon Callihan

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2- On May 4,1983, pursuant to 10 CFR 50.55 (e) , the

_ $ff ._ _ -Commonwealth Edison ' Company (" Edison") notified the NRC of a

-i f~ design deficiency in the undervoltage attachment of the DS-

---* = " - 416 switchgear. The deficiency had been identified by

' ?M , Westinghouse during an evaluation of the switchgear conducted A,n - .bh on account of operational failures at other plants. Edison's

. J g=em June 3,1983 letter fulfills 10 CFR 50.55 (e) reporting

.EM1:~ P requirements by providing a description of the deficiency,

Q' an analysis of its safety implications and an explanation of 3 0

the corrective action taken. Because of the corrective M .' . action to be implemented -- the installation and testing, M '~. , _ before fuel load, of new, redesigned undervoltage attach-Af'

• ments in all DS-416 switchgear -- there is no need to change

"pr any testimony already heard in the licensing proceedings.

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, , one First Nabonat Pla:a. Chicago. Illinois Adoress Reply to: Post Omce Box 767 ,

CNeago, lilinois 60690 June 3, 1983 Mr. James G. Keppler, Regional A.d.hinistrator

- Region III

• U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137 l

Subject:

Byron Station Units 1 and 2 Braidwood Station Units 1 and 2 10 CFR 50.55(e) 30 Day Report DS-416 Reactor Trip Switchgear NRC Docket Nos. 50-454/455 and 50-456/457

Dear Mr. Keppler:

On May 4, 1983, the Commonwealth Edison Company Project Engineering Department notified Mr. L. McGregor of your office of a deficiency reportable pursuant to 10 CFR 50.55(e) regarding the DS-416 Reactor Trip Switchgear at our Byron and Braidwood Stations.

For your tracking purposes, this deficiency was assigned Number 83-06 for our Byron Station and Number 83-05 for our Braidwood Station.

requirements Thisof letter 10 CFR fulfills 50.55(e) the thirty (30) day reporting regarding this matter and is considered-to be a final report.

Descriobion o f De ficiency The reactor trip breakers 'and reactor trip bypass b'reakers at Byron /Braidwood Stations are Westinghouse Model DS-416. Due to a s

e discrepancy in design, there is a potential for m'isoperation of the undervoltage (UV) attachment in the breakers. The width of'the retaining ring on the two pivot shaf ts of the UV trip (refer to attachment) is not compatible .with the width of the groove on the pivot shafts that receives the retaining ring. The groove in the shaft receiving the retaining, ring was not increased in width to be l consistant with an earlier (1972) retaining ring design change.

new retaining ring is wider than the original design and does not The seat properly in the existing grooves. This could cause the-i retaining ring to become disengaged from the pivot shaft and allow.

the pivot shaf t to move laterally and come out of its guide hole.

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Analysis of Safety .Imolications The deficiency described above increases.the potential for misoperation of the DS-416 undervoltage attachment, thereby creating a condition wherein the reactor trip switchgear might not open on automatic demand from the reactor protection system. However, the reactor could be tripped manually by energizing the shunt coil of either reactor trip breaker to prevent any adverse safety '

consequences. -

Corrective Action Westinghouse will supply replacement UV attachments for the 05-416 reactor trip switchgear. The new attachments have modified (widened) grooves to accommodate the new retaining rings.

Manufacturing drawings have been revised and quality control procedures modified to assure that critical design dimensions are maintained during manufacture. Furthermore, Westinghouse is developing and will implement a procedure for installation of .the new attachments on DS-416 reactor trip switchgear in the plant.

This field installation procedure will provide for proper alignment and interface of the attachment with the breaker trip shaft. s-Westinghouse will supply the new UV attachments by October, 1983.

The new UV attachments will be installed and tested prior to fuel load.

Please address any questions that you or your staff may have concerning this matter to this of fice.

Very truly yours y-E, Douglas Swar z tuclear Licensing Administrator Attachment cc: RIII Inspector - Byron .

RIII Inspector - Braidwood Director of Insp. and Enf.

• U.S. Nuclear Commission Washington, DC ,

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