ML20086E139

RO 95-002:on 950605,invalid Failure of Division 13,HPCS EDG Occurred.Surveillance Procedures Used for ECCS Testing Will Be Evaluated to Provide Alternate Method for Initiating Trip Signals,Thereby Eliminating Need for Finger Relays

ML20086E139
Person / Time
Site:	Grand Gulf
Issue date:	06/30/1995
From:	Hutchinson C ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GNRO-95-00077, GNRO-95-77, NUDOCS 9507110244
Download: ML20086E139 (2)

Text

i I.. e' ENTERGY: l"!!M""*" '"* *

, Pott Gbson. MS 39150 Tel 601437 2M)0 C. R. Hutchinson ,

ve e Resavn June 30, 1995 acam ow waw san U.S. Nuclear Regulatory Commission i Mail Station P1-137 4 Washington, D.C. 20555 Attention: Document Control Desk ,

Subject:

Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License No. NPF-29 Special Report 95-002 invalid Failure of Emergency Diesel Generator 13 Due to Trip on Loss of Excitation GNRO-95/00077 ,

Gentlemen:

i On June 05,1995, an invalid failure of Division 13, High Pressure Core Spray, (HPCS) Emergency  !

Diesel Generator (EDG) occurred. The failure occurred while attempting to close the EDG output breaker during a routine monthly surveillance. Upon closure of the output breaker, the engine tripped on loss of excitation.

On a refueling outage frequency, tests are performed to verify that certain EDG trips are bypassed in an emergency. During this emergency core cooling system (ECCS) testing, the EDG is given a loss of coolant accident (LOCA) signal. While the LOCA signalis present, various EDG trip signals are initiated. The process for making up contacts necessary to generate these trip signals required use of the electrician's finger (finger the relay). While making up the contact for loss of excitation, excessive force was used and the contact apparently was bent. The loss of excitation trip was the last part of the ECCS testing to be performed before the engine was shut down and declared operable. The loss of excitation trip remained in until the monthly surveillance was run thirty days later and caused the June 05 trip.

The standard practice during ECCS testing had been to finger relays. This method had been used l with no adverse results until the June 05 event. However, the June 05 event brought to light the need to determine a better method for initiating trip signals. As a result, the surveillance procedures used for ECCS testing will be evaluated to provide an alternate method for initiating trip signals, thereby eliminating the need to finger relays. 1 The loss of excitation trip is bypassed during a LOCA. However, this trip is not bypassed during a loss of offsitegfgP]. The loss of excitation trip did not present an increased risk to the 9507110244 950630 t I p PDR ADOCK 05000416 S PDR

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( general public due to the fact that (1) the trip is bypassed in a LOCA, (2) the June 05 event

! occurred while the plant was shut down for a refueling outage with the reactor depressurized, and l (3) both division 11 and 12 EDGs were available to power safe shut down and decay heat removal systems.

l The justification provided in the previous paragraphs support the conclusion that the June 05,1995 l

trip of the Division 13 EDG was an invalid failure. Therefore, in accordance with Regulatory Guide 1.108, this report is being made pursuant to GGNS Surveillance Requirement 4.8.1.1.3.

l Yours Truly, CRH/JEO CC: Mr. J. E. Tedrow Mr. H. W. Keiser Mr. R. B. McGehee Mr. N. S. Reynolds Mr. H. L. Thomas Mr. Stewart D. Ebneter Regional Administrator U.S. Nuclear Regulatory Commission Region ll 101 Marietta St., N.W., Suite 2900 Atlanta, GA 30323 Mr. P. W. O'Connor (w/2)  !

Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission ,

Mail Stop 13H3 l Washington, D.C. 20555 l l

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