ML20085J825

Ro:On 740617,during Surveillance Testing,Containment Cooling Svc Water Pump 3B Failed to Start.Caused by Open Racking Screw Cover on Circuit Breaker.Equipment Operator Closed Cover.Procedure Change Initiated Re Insp of Cover

ML20085J825
Person / Time
Site:	Dresden
Issue date:	07/03/1974
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
References
483-74, NUDOCS 8310190110
Download: ML20085J825 (3)

Text

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~A Ccmm One Firstganalrlth Edis Plata.

Address Reply to: Post Othee Box 767 n Chicago. litinois Q

Chicago, ilhnois 60690 4

, BBS Ltr.f483-74 Dresden Nuclear Power Station R. R. #1 t

Morris, Illinois A [

July 3, 1974 60450 @ @N 'N,

. M h5 Mr. J. F. O' Leary, Director tt N.121974 Directorate of Licensing ( er U

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U. S. Atomic Energy Comission 50-249 \s , j Washington, D. C. 20545 c. ,

SUBJECT:

LICENSE DPR-25. DRESDEN NUCLEAR POWER STATION. UNIT #3, REPORT OF i-UNUSUAL EVENT PER SECTION 6.6.B.2 07 THE TECHNICAL SPECIFICATIONS.

3 FAILURE OF 3B CONTAIhMENT COOLING SERVICE WATER PUMP TO START.

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Reference:

Drawing: P&ID M-368

Dear Mr. O' Leary:

This letter is to report a condition relating to the operation of the unit at about 0400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br /> on June 17, 1974. At this time, a containment cooling pump failed to start during surveillance testing of the pump. This i

malfunction is contrary to section 2.a.l.c of Regulatory Guide 1.16 which >

that "any condition involvin;; 01..;,1 p:::ible fail..:e .f..ier., Ier a system intended to be designed against assumed single failure, could result in a loss of the capability of the system to perform its safety function."

PROBLEM i i With Unit 3 at approximately 632 MWe, preparations were made to 4 take the Unit 3 diesel' generator out of service for its annual inspection.

The Technical Specification (section 3.5.F.1) states in part "when any unit or shared diesel generator is inoperable, continued reactor operation is permissible only during the su:ceeding seven days provided that all of the low pressure core cooling and containment cooling subsystems shall be operable". As part of the station's normal procedure, the LPCI and contain-ment cooling service water pumps were started to demonstrate system operabi-lity. When the equipment attendent. attempted to start the 3B containment cooling service water pump, the pump failed to start. The other three containment cooling service water pumps and the other components of contain--

ment cooling functioned normally. This action brought the status of the CCSW pumps into compliance with the Technical Specification (Section 3.5.B.2) which states: "When it is determined that one containment cooling service water pump is operable, the remaining components of that subsystem and the other containment coeling subsystem shall be demonstrated to be operable immediately and dr.ily thereaf ter." This action was completed by 4:10 a.m.-

on June 17,'1974. The normal function of the containment cooling 1 (,-/ ystem -

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Mr. J. F. O'Lisr0 O' July 3, 1974 is to provide cooling water to the LPCI heat exchanger. The containment cooling service water pumps circulate water from the crib house, through the LPCI heat exchanger and discharge the water to the main service water discharge piping.

INVESTICATION Following the failure of the 3B CCSW pump to start, an equipment operator was sent to check the circuit breaker for this pump. He found that the racking screw cover was not closed all of the way. This cover includes a safety device which prevents the breaker from being electrically charged when the cover is not completely closed. This cover is spring loaded and is supposed to close automatically when the racking screw tool is withdrawn.

In this case, the spring failed to close the cover completely.

1 CORRECTIVE ACTIONS I i

The equipment operator closed the cover completely. The 3B CCSW '

pump was then started without further problems. This work was completed  !

by 4:45 a.m. on June 17, 1974 and the Unit 3 diesel generator was taken out- '

of-service shortly thereafter. A work request has been initiated by shif t personnel to inspect the 3B CCSW pump circuit breaker. This work request 2 is not yet completed. Additionally, a procedure change has been initiated which will require inspection of the racking screw cover operation every rima tha 4xv mir cirem t neaavar. ava in.pected. Peth the br: h:r in:p::ti:r.

and procedure revision should be completed by July 31, 1974.

EVALUATIONS There was no effect on the safety of operation during the period of uncorrected condition. Surveillance revealed that the other three CCSW pumps were operational. Thus, neither the CCSW system nor the subsystem consisting of A and B CCSW pumps was inoperable at any time.

Tlie immediate actions to correct the condition and bring the status into compliance with the Technical Specifications were appropriate.

The Technical Specifications provide for certain actions in event of a ,

CCSW pump failure and these actions were followed. The problem with the '

I pump was investigated and established quickly and the pump was returned to operational status very soon af ter discovery of its failure to start.

Follow-up actions have been appropriate and should minimize the probability of future failures of this type.

A review of station records revealed that no prior occurrances of this nature have been reported. Because of the lack of any previous history of failure of the racking screw cover to close, the continued operation of the unit is justified. The remaining investigations and .

actio:-. involve inspection of the breaker racking screw cover and a pro-cedure change to insure this inspection will be performed during each h.

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Nr. J. F. O'Ler July 3, 1974 maintenance of b similar type of breaker even though, judging by past history,

' this was an isolated failure. In addition, the 4KV breaker checklist associated with the equipment outage check-off list will have a column added to include checking for closure of the racking screw cover when returning 4KV circuit breakers to service.

Sincerely, ^

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f/B. Stephenson f4.<25

./ Superintendent

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