ML20042E160

LER 90-002-00:on 900318,inadvertent ESF Actuation Occurred When Emergency Start Signal Reset.Caused by Procedure Inadequacy When Emergency Start Signal Still Present on Train B.Sys Operating Procedure revised.W/900411 Ltr

ML20042E160
Person / Time
Site:	Summer
Issue date:	04/11/1990
From:	Bradham O, Higgins W SOUTH CAROLINA ELECTRIC & GAS CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-002, LER-90-2, NUDOCS 9004200303
Download: ML20042E160 (4)

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' 1 10CFR50.73; .

e' SIuth Cer: lina Electele & Gas Company" - ollb $. bradham -

• - P.O. Box 68 - . . Vic) Presid nt J:nkin2ville, SC 29035 '~ Nucbir Operations '

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April 11, 1990 a

1 Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555

SUBJECT:

Virgil C.-Summer Nuclear Station N Docket No. 50/395 Operating License No. NPF-12 ,

LER 90-002 '

Gentlemen:

l Attached is Licensee Event Report No.90-002 for'the Virgil C. Summer Nuclear- .,

Station. This report is submitted pursuant to the requirements of '

10CFR50.73(a)(2)(iv).

Should there be any questions, please call us at:your convenience. d Very truly yours, O. S. Bradham-DCH/0SB: led Attachment c c: D. A. Nauman/0. W. Dixon, Jr./T. C. Nichols, Jr.

E. C. Roberts- .

R. V. Tanner J. C.-Snelson S. D. Ebneter R. L. Prevatte J. J. Hayes, Jr. J. B. Knotts, Jr. '

General Managers INP0 Records Center C. A. Price ANI Library G. J. Taylor Marsh & McLennan '

J.-R. Proper NPCF R. B. Clary NSRC F. H. Zander. RTS (ONO900019)

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On March 18, 1990, at approximately 0230, hours during performance of Surveillance Test Procedure (STP) 170.015, an emergency start signal was present on the "B" train diesel generator and, per the procedure, the operator attempted to reset the emergency start signal. The diesel was disabled by placing the mode selector switch to the maintenance mode; however, when the diesel generator mode selector switch was returned to the operational mode, the diesel started. This start constitutes an inadvertent ESF actuation.

The diesel generator was monitored and verified to achieve proper speed and voltage as required from an emergency start signal. Also, all support systems were verified to function properly.

The "B" diesel generator circuitry is designed such that when the mode selector is in the maintenance mode the emergency start override push button in the main control room is disabled but the local override push button is operable. The procedure specifically referred to the emergency start override push button in the main control room to be used to reset the diesel even though the mode selector was in the maintenance mode. Thus, when the mode selector switch was taken out of the maintenance position, the diesel generator started because the emergency start signal was still present.

The diesel generator was then shut down and placed in standby per the applicable System Operating Procedure and a change to the procedure to require the emergency l

start to be reset locally was init Mted.

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i' l PLANT IDENTIFICATION' Westinghouse - Pressurized Water Reactor EQUIPMENT IDENTIFICATION:  ;

Emergency Diesel Generator EIIS-0G JOENTIFICATIONOFEVENT:

An inadequate procedure caused the inadvertent start of "B" train Emergency Diesel l Generator. i i

EVENT TIME AND DATE:

March-18, 1990 at 0200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br />.

REPORT DATE: l April 11, 1990 This report was initiated by Off-Normal Occurrence Report 90-019.

CONDITIONS PRIOR TO EVENT:

Mode 1,'100% power. 5 DESCRIPTION OF EVENT:

Surveillance Test Procedure (STP) 170.015. " Fire Switch Functional Test.For l d XPP-0043C, CHG/SI Pump.C," verifies the fire switch capability to isolate the "C" Train Charging (CHG)/ Safety Injection-(SI) pump from it-s control circuitry in the control' room. Part of the test involves actuating a relay that would emergency.

start the "C" CHG/SI pump as well as the "B" diesel generator. Because the-scope of this procedure does-not involve starting the diesel generator. the_ procedure directs the ditsel generator mode selector switch to be placed in the maintenance j mode (thispreventsthedieselfromstarting).

On March 18, 1990, at approximately 0230, hours during performance of STP-170.015,

, an operator reset the emergency start signal as described in the procedure; however, when the diesel generator mode selector switch'was taken out of the.

maintenance position, the diesel started.- This start constitutes an inadvertent ESF actuation.

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The diesel generator was monitored and verified to achieve proper speed and voltage 'l as required from an auto start. Also, all support systems were verified to i function properly. .j.

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A review was done of STP-170.015 and the control circuitry for the "B" diesel-generator. This review indicated that the_ procedural step that reset-the emergency start signal specifically_ referred to the emergency start override push _ button in the main control room. The review also indicated'.that the "B" diesel generator.

circuitry is designed such that when the mode selector is in the maintenance mode =

the emergency start override push button in the main control room is disabled, but.

the local emergency start override push' button is operable. Therefore, even though-the procedure recognized that-the emergency start signal needed to be reset, the direction given to accomplish this was incorrect.- Thus, when the mode selector 7 switch was taken out of the maintenance position, the diesel generator started .

because the emergency start signal was still present.

ANALYSIS OF EVENT:

The diesel generator was aligned to stand-by conditions with the exception'of the mode selector switch and all support systems were operable. When the mode selector was taken out of the maintenance position, the diesel as well-as all required support systems started normally. With the diesel' generator running, the reliability of the 1E Bus is increased; therefore, no safety consequences occurred as a result of this event.

IMMEDI ATE CORRECTIVE ACTI.0._t!:

The diesel generator was'immediately monitored to verify proper operation.

The diesel gene,ator was then shut down and placed in standby per the applicable System Operating Procedure.

• An immediate change to the procedure to require the emergency! start signal to be reset locally (this will reset the emergency' start signal at all: times) was '

initiated. Also, an additional procedure, which performs a similar test on the "B" charging pump, was revised accordingly.

ADDITIONAL CORRECTIVE ACTION:

A meeting of the Management Review Board was held on April 3, 1990, to review this event. The purpose of the meeting was to assure that management level attention is given to the event such that plant performance is enhanced. The Board recognized that the procedure change process could have possibly identified the procedural deficiency; therefore, as a result, a review for enhancement of the procedure change process will be performed.

l u PRIOR OCCURRENCES:

l l- None.

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