ML20085K175

Ro:On 731001,following Routine LPCI Sys Surveillance,Valve MO3-1501-20B Failed to Close Causing Breaker to Trip. Cause Not Found.Breaker Reset

ML20085K175
Person / Time
Site:	Dresden
Issue date:	10/18/1973
From:	Worden W COMMONWEALTH EDISON CO.
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
781-73, NUDOCS 8310200251
Download: ML20085K175 (3)

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Mr. A. Giambusso

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SUBJECT:

_LIC:532 DPR-2 5, rysrPN NUCL"*J PO'.;En STATION, UNIT _v3 9

SECTIC' 6.6.C.1 GT 1::C:iNICAL St.:CIFIC\\ TION ;.

LPCI 1 M : L';r. '.qi-1501

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Reference:

Drawing M-29 Dresden Station P & ID

Dear Mr. Giachusso:

L This letter is to report a condition relating to the operation of the unit at about 2200 hours0.0255 days <br />0.611 hours <br />0.00364 weeks <br />8.371e-4 months <br /> on October 1, 1973. At this t ime, valve If03-1501-203 (low pressure core injection flow test valve) failed to close and its breaker trivead.

Thii -alfunction in contrerv t o rect ica 3. 5. A. 3 of the Technical Specifications which requires that the low pressure core

- r injection (LPCI) system be operable when irradiated fuel is in the core.

PROBLEM Following the conclusion of routine LPCI system surveillance testing, the control switch for LPCI system test valve M03-1501-20B was placed in the closed position. When the switch was placed in tha clused position, the supply breaker for the M03-1501-203 valve tripped.

/0, At the time of the occurrence, the unit was in the "Run" mode and thermal power was about 2289 megawatts.

The unit was running steady h

with an electrical load of 760 megawatts.

O' To ir:nediately correct the problem and return the LPCI system to an operatiom i status the breder was reset, end a secend atte pt va:

r.ade to clone the valve.

The second attempt proved to be succcesful, with

,3 the valve operating as desigr.ed.

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Mr. A. Giambusso October 18, 1073 l

INVESTICATION An investigation into the problem failed to determine the cause of the trip since the problem corrected itself once the breaker was reset.

This type of breaker problem has been experienced in the past, and is presently under investigation.

At present, the following have been done in attempting to solve the problem:

1.

This type of breaker was tested at the company Technical Center under various loads and temperatures. The purpose of the test was to determine if the magnetic trip settings of the breakers were shifting.

2.

A modification is in progress to change some of the breaker overload heaters. The heaters to be changed were determined to be slightly over si:cd for their application.

3.

Torque switch, overload, and magnetic trip settir.gs are being collected on all valves in usa on units 2 and 3 ECCS and Primary Containment Systems. The data will be used to determine if differences exist between similar valves.

4.

Three breakers on valves which previously experienced this type of failure were tested on October 6,1973.

The results of these tests are being analyzed now.

Aprecedurehasbeenurittentoidentifythetypeofbreaker) 5.

or valve. failure.

Its purpose is to determine if the corque switch, overloads, or a magnetic trip prevented proper i

operation of the valve.

Hopefully these five steps will produce a solution to the problem.

The investigation will continue until a solution is determined.

CORRECTIVE ACTION The Lamediate corrective action taken was to reset the breaker and attempt operation of the valve a second time. As stated previously, the problem corrected itself af ter the breaker was reset. Also since this failure is still under investigation, future corrective action will be dependent on the findings of the investigation.

EVALUATION During the failure of the LPCI valve M03-1501-20B, the safety of the plant and public was not in jeopardy. Failure of the M03-1501-20B valve would not prevent either LPCI loop from injecting coolant, nor would it prevent correct operation of the torus spray ring header.

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Mr. A. Gintsusso October 18, 1973 The malfunction of this valve degraded the use of one of the two LPCI ficw test lines.

The second valve (3-1501-38B) in this line was operable and would have c1'osed on an initiation signal.

Continued operation of the unit was censidered to be safe because the second valve in the line was operable and the ability of the LPCI system to inject water into the reactor was not degraded.

Sincerely, k.u.h b Olcys (g.,W.P.Worden r Superintendent WFW:do 4

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