ML19210A219

Abnormal Occurrence 50-289/75-12:on 750421,reactor Bldg Emergency Cooling River Water Pump Failed to Start on Automatic Signal.Caused by Component Failure of Intermittent Contact on Control Room Switch

ML19210A219
Person / Time
Site:	Three Mile Island
Issue date:	05/01/1975
From:	Arnold R METROPOLITAN EDISON CO.
To:
Shared Package
ML19210A220	List: ML19210A219 ML19210A223
References
NUDOCS 7910240933
Download: ML19210A219 (4)

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TO: Director, Division of 0:llG CC ' OlliEi; S E ,; i A E C P D '1._ XX _ __ _

SENT l.OCAL PDo XX Reactor Licensin:; 1 signed 1 C t. ASS U:-:CLA5a Pi1 0 P li;l- O ' INPUT NO CYb F.EC'D DOCiOTr:D:

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.D E S C f;iP i: 0 ." Ltr concerns abnor=al occurrence . . _ . - - - _ .U NC LOM'O S -

nu=ber A0 50-289/75-12 en h-21-75, Failure of the 1B Reacter Building Emergency Ccoling  ;'

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gi;;) __O METROPOLITAN EDISON COMPANY  :-  : -x m u _. n .s -

PCST OFFICE tCX 542 R E ACING. PENNSYLVANI A 19603 TELEPHONE 215 - 929-3601 May 1, 1975 cu GQL 1011 / D N $s??n?

Director 5E MAY 91975 > -5 Division of Reactor Licensing U.S. Nuclear Regulatory Commission v.s. ""5"""

Ng'Aj,','c7" g Washington, D.C. 20555 q).

Dear Sir:

D s Operating License No. DPR-50 Docket No. 50-289 In accordance with Technical Specifications for the Three Mile Island Nuclear Station Unit 1 we are reporting the following abnormal occurrence:

(1) Report Number: A0 50-289/75-12 (2a) Report Date: May 1, 1975 (2b) Occurrence Date: April 21, 1975 (3) Facility: Three Mile Island Nuclear Station Unit 1 (TMI-1)

(4) Identification of Occurrence:

Title:

Failure of the 1B Reactor Building Emergency Cooling River Water Pump to Start on an ESAS Signal Type: An abnormal occurrence as defined by the Technical Specifications, paragraph 1.8d, in that 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:

, jN Power: Co re : 99% /sy ._,.,jj. .

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Elec.: 850 W (Gross) $ .

6 RC Flow: 136 x 10 lbs/hr 'T~ ,_s .

5 ', } i-3p6 250 RC Pressure: 2130 psig -> :.. ,,

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RC Temp.: 579 F PRZR Level: 240 in.

PR2R Temp. : 655 F

'6) Description of Occurrence:

During a High and Low Pressure Injection Surveillance Test (1303-5.2),

Reactor Building Emergency Cooling River Water Pump RR-PlB failed to start on an automatic Engineered Safeguards test signal. The pump was then successfully started manually from the control room using the control room switch.

The redundant FR-PlA pump was then tested to verify operability.

Initial investigations detected no problems in the Engineered Safe-guards logic relay and connections in the breaker control circuit were checked and found to be tight. The test was resumed and the pump started successfully on all three logic combinations.

(7) Designation of Apparent Cause of Occurrence:

Further investigation showed that the apparent cause of the occurrence is component failure in that an intermittent contact on the control room switch caused the failure of the pump to start.

(8) Analysis of Occurrence:

It is believed that the failure of the RR-PlB pump did not represent a threat to the health and safety of the public as RR-PlB could be started from the control room, the redundant RR-PlA pump was available, and one reactor building emergency cooling river water pump is sufficient to supply emergency cooling water in the event of a loss of coolant accident.

(9) Corrective Action:

Immediate corrective action was taken as described above to return the pump to service. Further, a Special Operating Procedure was implemented to require that voltage measurements be taken to verify the contact in question is closed after each operation of the RR-PlB control switch.

Also the type contact in question was verified to be closed on other components using the same type control switch (BS-PLA, BS-PlB, DH-PlA, DH-PlB, and RR-PlA).

The Plant Operations Review Committee (PORC) met following the occurrence, reviewed and approved the immediate corrective actions, and in addition recommended as long term preventative actions that:

a. The control switch for RR-PlB be replaced and the cause of the intermittent contact be determined at that time.

b. Should the investigation of the RR-Plh switch determine that a potential problem exists with the five similar switches listed above, appropriate corrective actions will te taken (note: at present, it is not believed that such problev do exist).

1476 251

The Station Superintendent reviewed and approved PORC's findings, and steps have been taken to insure implementation of the long term pre-ventative actions.

(10) Failure Data:

a. Previous Failures:

Abnormal Occurrence Report 50-289/75-02 also dealt with a failure of RR-PlB to start on an automatic ESAS signal. Al-though it was originally thought that the failure to start was due to loose connections in the 4KV breaker, it may actually have been due to the faulty control switch,

b. Equipment Identification:

General Electric Co. SB10 Switch Sincerely, i

R.C.A. ld Vice President-Gen- ration RCA:RSB:tas cc: Office of Inspection and Enforcement, Region 1 U. S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406 File: 20.1.1 / 7.7.3.5.1 1476 252