ML18219D840

Reporting Electrical Design Problem, Identified When Attempting to Restart Containment Spray Pumps with Unit 2. Concluded No Significant Safety Problem

ML18219D840
Person / Time
Site:	Cook
Issue date:	01/30/1978
From:	Shaller D Indiana Michigan Power Co, (Formerly Indiana & Michigan Power Co), American Electric Power Service Corp, American Electric Power Company
To:	James Keppler NRC/RGN-III
References
Download: ML18219D840 (5)

Text

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0ESCRIPTION ENCLOSURE Informing of condition discovered at Units 1 & 2 during the Unit No 2 preope ational test program concerning elec design probl when attempting to restart containment spr pumps following the switchover of the Pump I suction from the refueling water storage t nk to the containment recirculation sump~

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Dhmekoan G~rii" MN < ~<CKBILIX DONALD C. COOK NUCLEAR PLANT P.O. Box 458, Bridgman, Michigan 49106 January 30, 1978 Donald C. Cook Nuclear Plant Units 1 8 2 Docket Nos. 50-315 and 50-316 DPR Nos. 58 5 74 Mr. J. G. Keppler, Regional Director Office of Inspection and Enforcement United States Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137

Dear Mr. Keppler:

.j This letter is to inform you of a,condition at the Donald C. Cook Nuclear Plant Units l,,and 2 that was di'scovered during the Unit No. 2 preoperational test program while performing the emergency power system train independence test. An electrical design problem was identified when attempting to restart the containment spray pumps following the switchover of the pumps'uction from the refueling water storage tank to the containment recirculation sump as follows:

When the pump control switch was removed from the "pull to lock-out" position the pump breaker closed due to the standing start signal from the containment Hi-Hi pressure signal. The control switch then v(as moved through, the "trip" position which reopened the breaker. The circuit design is such that the "standing closed" position is superseded by the "anti-pumping" protection feature of the breaker which prevents the breaker from closing when placed in the "run" position.

During the testing the pump was restarted within fifteen seconds. The standing start (closed) signal can be removed by resetting the containment spray signal. How-ever, the reset push buttons are spring loaded to the non-reset position.

As a result of these findi ngs all applicable operating procedures have been revised to read as follows:

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January 30, 1978 Page 2

1. Push and hold both spray actuation reset buttons 4 'dlllEI

2. Start the affected containment spray pump

3. Release spray actuation reset button A design change has already been incorporated on Unit 2 such that the lockout feature will not reclose the pump breaker until the control switch is returned to the neutral position. The same design change will be instituted on Unit 1 during the next refueling outage.

A safety evaluation was performed to establish the consequences of the above problem in the unlikely event of a loss of coolant accident.

Results of this evaluation indicate that the consequences are consistent with the plant design basis. Therefore, the above cited incident does not consti-tute either an unreviewed safety question or an adverse affect on the health and safety of the public.

Since the occurrence does not prevent the Plant from performing its intended design safety functions and steps required to circumvent the switch operation problem have already been instituted into existing pro-cedures, we conclude that no significant safety problem did exist or exists today on either Unit 1 or Uni t 2.

Very truly yours, D. V. Shaller Plant Manager DVS:pk cc: J. E. Dolan R. W. Jurgensen G. E. Lien R. Kilburn R. J. Vollen BPI K. R. Baker RO:III R. C. Callen MPSC P. W. Steketee, Esq.

R. Walsh, Esq.

G. Charnoff, Esq.

G. Olson J. M. Hennigan PNSRC J. F. Sti etzel

RECElg EO 00CUHP.H l CO'lT lO~OESl(

U,S. HRC DlSTRlBUTIOH SERVlCES BRAHCH