ML19317D883

Abnormal Occurrence AO-269/74-17:on 741012,room Containing Low Pressure Injection Pumps 1B & 2B Flooded.Caused by Open Drain Valves.Evaluation of Sump Pump Reliability to Be Performed.Sump Pump Monitoring Alarm to Be Installed

ML19317D883
Person / Time
Site:	Oconee
Issue date:	10/25/1974
From:	DUKE POWER CO.
To:
Shared Package
ML19317D876	List: ML19317D874 ML19317D883
References
NUDOCS 7912100593
Download: ML19317D883 (2)

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• DUKE POWER COMPANY OCONEE UNIT 1 Report No.: A0-269/74-17 49 3; port Date: October 25, 1974 Occurrence Date: October 12, 1974 Facility:_ Oconee Unit 1, Seneca, South Carolina i Low pressure injection pump room flooding l Identification of Occurrence:

Unit 1 at various power levels, Unit 2 in Conditions Prior to occurrence:

cold shutdown

_ Description of Occurrence:  !

On October 12, 1974, a utility operator at the Oconee Nuclear Station dis- .

covered three feet of standing water in a pu=p room which contains low l

?? essure injection pucps 1B and 2B and reactor building spray pumps 1B and '

Zo. Electrical power was isolated to these pumps and operation of the '

redundant low pressure injection pumps 1A and 2A and reactor building spray Samples of the water were taken, and the pumps LA and 2A were verified.

results of chemical and gnnmn spectrum analysis indicated a radioactivity ,

level aol boron concentration consistent with water from the Low Pressure Injectica Systen.

A submersible pump and hose were used to pump the water to the low activity waste tank. Electrical and functional checks of the low pressure injection and reactor building spray pumps were performed to verify operability.

Designation of Apparent Cause of Occurrence:

On October 9, 1974, the Oconee Unit 2 d.ecay heat cooler 2B was isolated in The cooler was drained to the preparation for inspection of valve 2LP-14. Drain valves 2 LWD-12, 2 LWD-272, 2 LWD-hfgh activity waste tank.

20WD-373 were ('ened to drain the piping header between the cooler and the This water drains to the pump room floor 2B low pressure rajection pu=p.

sump pumps.

and then is pumped to the high activity waste tank with auto the B low pressure injection header had been completed by the control room operator by closing remotely operated valves 2LP-34, 2LP-13, and 2LP-18; however, he did not visually verify that the valves were closed.

The water drained frem theThe header to the automatic floor cycling drains sump at apparently pumps the base of 2B low pressure injection pump.

tripped due to a pu=p overload and the water draining to the pump room collected. The utility operator c'id not closeItthe header drain valve could not be determined because he thought the header was isolated.

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.whether the header had been isolated; however, leakage from the header allowed the pump room to te flooded to a depth of three fest.

Analysis of Occurrence:

The two low pressure injection pumps are mounted on high bases aad the water in the pu=p room did not rise sufficiently to affect them. The motors for the 13 and 23 reactor building spray pu=ps were partially submerged and thus one train of Reactor Building spray was re=oved from service for both Units 1 and 2. The redundant Reactor Building spray pu=ps, located in another pump room, were unaffected by this incident and were tested to verify operability as soon as this condition was identified. Technical Specification 3.3.5 permits maintenance on one string of low pressure injection and Reactor Building spray for a period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The basis of this acceptability is the small probability of failure within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> following a demonstration.

The draining of the pump room and subsequent verification testing of the affected components was completed 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> after initial discovery. It is concluded that the health and safety of the public was not affected.

Corrective Action:

In order to prevent similar occurrences, an evaluation of sump pump reliability will be perfor=ed. A modification will be made to install a sump pump moni-toring alarm so that early pump failure may be detected. A meeting was held on October 15, 1974 with the station Manager and all supervisore which stressed the necessity for attention to detail and completeness in any station operation.

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