ML19343C351

AO 50-219/74/32:on 740521,relay 16K114D in Sys 2 Core Spray Booster Pump Initiation Logic Found in Energized Position. Caused by Failed Core Spray Booster Pressure Switch RV40D. Relay Placed in de-energized Position by Valving Out Switch

ML19343C351
Person / Time
Site:	Oyster Creek
Issue date:	05/31/1974
From:	JERSEY CENTRAL POWER & LIGHT CO.
To:
References
AO-50-219-74-32, NUDOCS 8103110849
Download: ML19343C351 (2)

Text

.

OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 Abnormal Occurrence Report No. 50-219/74/32 Report Date May 31, 1974 Occurrence Date May 21, 1974 Identification of Occurrence Failure of RV40D core spray booster pump pressure switch in the permissive position. This created a condition whereby had core spray booster pump NZO3B failed to start or failed to establish a discharge pressure, its associated redundant booster pump, NZO3D, would not have started automatically. This event is considered to be an abnormal occurrence as defined in the Technical Specifications, paragraph 1.15D.

Conditions Prior to Occurrence The plant was shut down for refueling. The reactor mode switch was in the

" Refuel" position and the reactor cavity was flooded.

Description of Occurrence While performing the annual surveillance test of the auto-depressurization initiation logic with System I core spray system disabled, it was observed that relay 16K114D in the System II core spray booster pump initiation logic was in the energized position. An investigation indicated that the System II core spray booster pump discharge pressure switch, RV40D, which actuates this relay, was in the closed position. The switch normally closes when the booster pump discharge pressure comes up to approximately 230 psig, thereby energizing the 16K114D relay. Normally closed contacts from the 16K114D relay act in conjunction with the 16K114B relay and pressure switch RV40B to trip the NZO3B booster pump and start the redundant NZO3D booster pump if proper discharge pressure is not established within five seconds. Failure of the RV40D pressure switch in the closed position created a condition whereby NZO3B would not have tripped if it failed to establish sufficient discharge pressure, and pump NZ03D would not have started since the logic was failed in the " satisfied" position.

P/q3N#fVf

. -. t Abnormal Occurrence No. 50-219/74/32 Page 2 Apparent Cause of Occurrence The cause of this occurrence has been traced to the failure of RV40D pressure switch. The failed switch is presently being tested in an attempt to determine the cause of the failure. The remaining RV40 switches in this syster. have been calibrated and found to operate satisfactorily under test.

Analysis of Occurrence The safety significance of this event is considered to be minimal since the reactor was in the shutdown condition with the cavity flooded.

Corrective Action The immediate action was to place the 16K114D relay in the deenergized position by valving out RV40D, which is the tripped condition. In this configuration, RV40B would have acted to : sense improper booster pump discharge pressure and started the redundant pump. The defective RV40D pressure switchins since been replaced and the replacement switch has been satisfactorily tested.

In the future, the RV40 pressure switches will be calibrated every three months rather than the present semi-annual interval. Also, similar switches in safety systems will be included on the three-month periodic calibration _ check.

Failure Data MERCOID Pressure Switch Type: DAh*43-156 R21E