ML19262A176

Abnormal Occurence 50-289/75-02:on 750103,1B Reactor Bldg Emergency Cooling River Water Pump Failed Start on Actuation Signal.Caused by Loose Electrical Connections & Possible Design Deficiency.Circuit Breaker Replaced

ML19262A176
Person / Time
Site:	Three Mile Island
Issue date:	01/13/1975
From:	Arnold R METROPOLITAN EDISON CO.
To:
References
NUDOCS 7910260502
Download: ML19262A176 (4)

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FILE: INCID m n :c r F RO:.* Metroplitan Edison Co DATE OF COC CATE R EC'3 LTR T'l!X ' RPT OT-i E R Reading, PA 1-13-75 1-16-75 xxx I R.C. Arnold xxxx ORIG CC OTHER SENT AEC PCR TO:

Directorate of Licensing 1-asigned SENT LCCAL PDR _m _

INPU i .,0 CYS REC'D CCCKET . ;C:

CLASS U::CLAES PROP !NFO .

xxxxx 1 50-289 DESCP.l? tic: - ENCLCSURES:

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Ltr reporting abnormal occurrence #75-02 on 1-3-75 concerning failure of the 13 reactor Building Emergency Cooling River Water Pump .

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METROPOLITAN EDISON COMPANY

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Directorate of Licensing ,

U. S . Atomic Energy Cocaission y Washington, D.C. 20545 _ _ _ .; -

Dear Sir:

Operating License DPR-50 Docket #50-289 In accordance with Technical Specifica1 tons for the Three Mile Island Nuclear Station 'Jnit 1, we are reporting the following abnormal occurrence:

(1) Report Number: A0 50-289/75-02 (2a) Report Date: J.S: 1 3 1975 (2b) Occurrence Date : January 3, 1975 (3) Facility : Three Mile Island Nuclear Generating Station Unit 1 (4) Identification of Occurrence:

Title: Failure of the 1B Reactor Building Emergency Cooling River Water Pump (RR-PIB) to Start on an ESAS Signal Type: An abnormal occurrence as defined by the Technical Specifications ,

paragraph 1.8d, in that the failure of the 1B Reactor Building Emergency Cooling River Water Pump to start on an ESAS Signal threatened to cause an Engineered Safety feature or system to be incapable of performing its intended function.

(5) Conditions Prior to Occurrence:

The reactor was at steady state power with major plant parameters as follows:

Power : Co re : 100% ,

a Elec: 862 MW (Gross) . r RC Flow: 140 x 106 lb/hr \

468

RC Pressure : 2155 psig

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• RC Temp.: 579 F PRZR Level: 235 in.

P RZR Temp . : 6500F (6) De scrit tion of Occurrence:

During i High and Low Pressure Injection Logic and Component SurveiJlance Test (1303-5.2), the Reactor Building Emergency Cooling River Water Pump RR-Pl3 ~ ailed to start on an automatic Engineered Safety features test signal. The pump had started successfully on two previous automatic test signals. Investigation revealed that the pump did not start on an ESAS signal because the circuit breaker had failed to close.

The redundant Reactor Building Emergency Cooling River Water Pump RR-P1A was started to verify operability. A spare circuit breaker was tested, used to replace the circuit breaker that f ailed, and the ef fected pump was returned to service .

(7) Designation of Apparent Cause of Occurrence:

A visual inspection of the initial circuit breaker revealed several loose electrical connections resulting in the spring release c)il not being energized when the close signal was applied. As this coil must be energized to close the circuit breaker, the motor circuit breaker did not close and the pump did not start.

It is believed that the apparent cause of the occurrence is manufacture in that the connections most likely were not sufficiently tightened when assembled : however, design has not been ruled out as a possible cause of the occurrence in that if sufficient lock washers had been utilized on the connections , possibly tight connections would not have been able to work their way loose.

(8) Analysis of Occurrence:

It is believed that the failure of the RR-P1B Reactol Building Em :gency Cooling River Water Pump to start did not represent a threat to the health and safety of the public in that only one Reactor Building Emergency Cooling River Water Pump is necessary to supply sufficient emergency cooling water in the event of a loss of coolant accident and it was verified that the RR-PlA pump was available .

(9) Corrective Action:

Immediate correctivc action was taken as described above to return the effected pump to service. In addition, terminations were tightened on the effected breaker that was removed from service, and the breaker tested satisf actorily .

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The Plant Operations Review Committee (PORC) met shortly after the

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occurrence and approved the i= mediate corrective actions. Also, as

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- is noted in our report A0 50-289/75-1, it is presently anticipated that an inspection of all 4 KV ES breakers will be completed within the next two to four weeks; and steps will be taken to contact the manuf acturer and correct any possible design deficiencies that may exist.

(10) Failure Data:

a. Previous Failures:

See Abnormal Occurrence Report 75 -01

b. Equir v at Identification :

Westinghouse Air Circuit Breaker 50 DH-P 350 Style: 25Y4440B1 Amps: 1200 Rated KV: 4.16 Mech: FAB SPRG Sincerely,

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, /Y.w R. C. old Vice President RCA:RSB :tas cc: Directorate of Regulatory Operations, Region 1 U. S . Atomic Energy Commission 631 Park Avenue King of Prussia, PA 19406 File: 20.1.1 7.7.3.5.1

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