ML20154C557

Forwards PRA Insp Repts 50-373/88-16 & 50-374/88-15 on 880627-0722 & Notice of Violation.Addl Concern Re Unreliability of Air Compressors at Station Noted,Per 880831 Problems W/Unit 2 Drywell Pneumatic Sys Leading to Shutdown

ML20154C557
Person / Time
Site:	LaSalle
Issue date:	09/09/1988
From:	Miller H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:	Reed C COMMONWEALTH EDISON CO.
Shared Package
ML20154C561	List: IR 05000373/1988016 ML20154C557 ML20154C569
References
NUDOCS 8809140409
Download: ML20154C557 (2)

See also: IR 05000373/1988016

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Docket No. 50-373

Docket No. 50-374

Commonwealth Edison Company

ATTN: Mr. Cordell Reed

Senior Vice President

Post Office Box 767

Chicago, IL 60690

Gentlemen:

This letter forwards the results and conclusions of the PRA inspection of

the LaSalle County Station conducted between June 27 and July 22, 1988. The

purpose of this inspection was to assess the adequacy of activities affecting

items identified by the LaSalle Unit 2, Prcbabilistic Risk Assessment (PRA)

as contributing most to plant risk. While this PRA is not complete, no

significant change in the dominant contributors to plant risk is anticipated.

Two violations were identified during this inspection as described in the

enclosed Notice. A written response is required. One of these was of special

concern since it involved the failure to take prompt action to correct a

potential common mode failure of the station emergency diesel generator output

breaker closing circuits. The station had been informed in 1984 by your

Station Nuclear Engineering Department of industry problems with certain

relays used in the closing circuits of emergency diesel generators at LaSalle..

The station failed to take any corrective action until three failures of these

relays occurred at LaSalle in 1987. Corrective action is still not complete.

We request that you take prompt action in determining if the station staff is

adequately trained to recognize and respond to significant safety issues.

Your response should describe those actions you plan to take to ensure that

significant safety issues are promptly addressed and corrective action completed

within a responsible period of time.

Another safety concern identified during the inspection was the unreliability

of the air compressors at the station. Specifically, the instrument air,

drywell pneumatic, and diesel generator air start system compressors all

exhibited poor reliability. This concern was underscored subsequent to the

inspection by problems with the Unit 2 drywell pneumatic system on August 31,

1988 leading to a plant shutdown. All of these systems are identified by the

PRA as dominant contributors to plant risk. Your response should address your

plans for increasing the reliability of these systems.

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Commonwealth Edison Company 2

In accordance with 10 CFR 2.790 of the Commission's regulations, a copy

of this letter, the enclosures, and your response to this letter will be

placed in the NRC Public Document Room.

The responses directed by this letter and the accompanying Notice are not

subject to the clearance procedures of the Office of Management and Budget

as required by the Paperwork Reduction Act of 1980, PL 96-511.

We will gladly discuss any questions you have concerning this inspection.

Sincerely,

DihGl% SiGNEQ B.( fitJslar J. I,IlLLER

Hubert J. Miller, Director

Division of Reactor Safety

Enclosures:

1. Notice of Violation

2. Inspection Reports

No. 50-373/88016(DRS);

No. 50-374/88015(ORS)

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cc w/ enclosures:

H. Bliss, Nuclear

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Licensing Manager

G. J. Diederich, Station

Manager

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Licensing Fee Management Branch

l Resident Inspector, RIII

Richard Hubbard

J. W. McCaffrey, Chief, Public

Utilities Division

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David Rosenblatt, Governor's

i Office of Consumer Services

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