ML18093B399

Special Rept 88-9:on 881215,non-valid Test Failure of Diesel Generator 2C Occurred.Caused by Equipment Problem.Cmc Switch Repaired & Diesel Generator Tested Satisfactorily. Investigation of Premature Contact Operation Continuing

ML18093B399
Person / Time
Site:	Salem
Issue date:	01/11/1989
From:	Miller L Public Service Enterprise Group
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
88-9, NUDOCS 8901200393
Download: ML18093B399 (3)

Text

--

e PS~G Public Service Electric and Gas Company P-.0. Box E Hancocks Bridge, New Jersey 08038 Salem Generating Station January 11, 1989 U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Dear.Sir:

SALEM GENERATING STATION LICENSE NO. DPR-75 DOCKET NO. 50-311 UNIT NO. 2 SPECIAL REPORT 88-9 This Special Report addresses the circumstances surrounding the No.

2C Diesel Generator non-valid failure 6ccurring on December 15, 1988. This report* is being submitted in accordance with the requirements of Technical Specification Surveillance 4.8.1.1.4. It is being submitted within 30 days as per the surveillance.

Sincerely yours, v1:Wf,_

L. K. Miller General Manager -

Salem Operations MJP:pc Distribution 8901200393 890111 PDR ADOCK 0~000311 S PDC

• .~I~ .2 S_PECIAL REPORT - - 9 PLANT IDENTIFICA':l'ION :_

Salem Generating Station - Unit 2 Public Service Electric & Gas Company Hancock's Bridge, New Jersey 0803~

IDENTIFICATION. OF QCCJJRR~~CE:

Non-valid test failure of 2C Diesel Generator Event Date(s): 12115188 Report Date: 1111189

• This report was initiated by Incident Report No.88-534.

This report addresses a test failure involving No.* 2C Diesel Generator (DIG) on December lSr i988. This report is submitteQ for informational purposes in accordance with Technical Specification Surveillance Requirement 4. 8 .1.1. 4 , .. and contains the information required by Regulatory Guide 1.108, Revision 1, August 197r, Regulatory Position C.3.b.

Technical Specification Surveillance Requirement 4~8.1.1.4 states:

"All diesel generat6r failures, valid or non-valid, shall be reported to the Commission pursuant to Specification 6.9.1.".

CONDIT.IONS PRIOR TO OCCl}RR_~l;:lCE:

Mode s Reactor Power 0% - Unit Load 0 MWe DESCRIPTION OF*OCCl}RRENCE:

On December 15, 1988 routine surveillance testing of 2C DIG was initiated in accordance with Technical Specification Surveillance 4.8.1.1.2. During the surveillance run, the "Generator Loss of PT Secondary Voltage" alarm actuated. The diesel was secured prior to loading. The alarm was manually reset after the D/G_was secured.

APPARENT CAUSE OF OCCl}RR_~J;:li:E :_

The root cause of this event has been attributed to an equipment problem.

In February 1987 one of the two original 2C DIG speed relays failed.

It was replaced with a new style speed relay. ~nvestigation revealed that the new style speed relay contact would sometimes prematurely actuate (upon start of the diesel) and cause the loss of PT secondary voltage* alarm circuit to enable prior to the generator output voltage attaining its design value (i.e., see Analysis of Occurrence}.

When the alarm occurred, the operator would pre~s the alarm reset switch clearing the alarm~ This indicated that the design generator output voltage had been attained. The alarm actuation was investigated. The cause was determined to be due to the new s~yle speed relay. Since the generator output voltage was reaching design value within the required time, this was deemed to not be a safety concern.

UNIT 2 SPECIAL REPORT ~9 Page 2 of 2 APPARENT CAUSE OF OCCURRENCE.~=-~<~c~o~n~t~'-d==-),_

j During this event, the alar~ reset sw~tch was use~, however, it did not clear the alarm. Since the alarm would not clear the operator shut the diesel .down. When the* diesel was shut down the alarm.reset swi tc.h did function. Investigation revealed that the alarm :r:eset switch was found to be defective. It would work intermittently. The PT voltage sensing circuit was found to be operable.

ANALYSIS OF OCCURRENCE:

The "Genera tor Loss *of .PT. Secondary Voltage"* alarm circuit is disabled when the D/G is not running. By approximately 850 rpm,* the generator field should have been flashed to allow the generator to build up generator output voltage to the design value. The alarm circuit is enabled at approximately 850 rpm, by the new style relay, so that the low voltage sensor can operate the ~larm. The operating speed of the diesel is 900 rpm. If sufficient generator output voltage has not been attained, the volta~e sensor will cause the alarm to energize.

With the unit in Mode 5, two D/Gs are required to be operational ~s per Technical Specification 3.8.1.2. During the time period of this.

event 2A D/G and 2B D/G were operable.

This event was classified as a non-valid failure in accordance with Regulatory Guide 1.108. Subsequently, no change in the D/G testing interval is required. This report is being submitted for informational purposes, in accordance with Technical Specification Surveillance Requirement 4.8.1.1.4.

CORRECTIVE - ACTION:--

The CMC switch was repaired and the D/G tested satisfactorily.

Investigation ~f the prematur~ ~ontact operation of the new style speed relay is continuing.

FAILURE DATA:*

New Style Speed Relay: Alarm Reset Switch:

Airpax, P/N 080-300-1147 P/N 911BRA531BC Precision Control Tachometer Microswitch Fort .Lauderdaie Division General Manager -

Salem Operations MJP:pc SORC Mtg.89-003