ML20045D301

Special Rept 93-002:on 930521,invalid Failure of Sdg 12 Occurred Due to False High Jacket Water Temp Signal, Generated by Faulty Jacket Water Temp Switch.Faulty Switch Replaced

ML20045D301
Person / Time
Site:	Grand Gulf
Issue date:	06/18/1993
From:	Hutchinson C ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
93-002, 93-2, GNRO-93-00075, GNRO-93-75, NUDOCS 9306280195
Download: ML20045D301 (2)

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Entergy operations. Inc. >

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Ftxt Goun MS 39150 j Td 601437 2MO i C. R. Hutchinson j w.e Ped.w i June 18, 1993 a4m u, .

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U.S. Nuclear Regulatory Commission  !

! Mail Statioi. P1-137 Washington, D.C. 20555 l Attention: Document Control Desk-i

Subject:

Grand Gulf Nuclear Station

f. Unit 1  ;

i Docket No. 50-416 l j License No. NPF-29 i Special Report 93-002 ,

{

Invalid Failure of Emergency Diesel Generator 12 Due  !

to False High Jacket Water-Temperature Signal i

• f GNRO-93/00075  !

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Gentlemen:

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! On May 21, 1993 following an outage )f Standby Diesel Generator

• (SDG) 12, a maintenance test was being performed to verify the'  ;

correctness of performed maintenance. SDG 12 was' started-in '

accordance with-plant operating instructions.and reached rated I speed and voltage. However, approximately two minutes-following the start, an automatic shutdown occurred as a result of a Group 2 trip signal. '

i l Subsequent investigations revealed that the trip occurred due to l an erroneous high jacket water temperature signal that was ,

i generated by a faulty jacket water tenperature switch '

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' (1P75N162B). The switch was venting the pneumatic trip system at temperatures below the normal trip setpoint (20013 degrees F) .

1 The. switch was found to be tripping at approximately 137 degrees.

j' The switch was replaced and the trip setpoint of the newly installed switch was determined to te approximately 201 degrees.

I The SDG trip is attributed to the maifunction of equipment that j is not operative in the emergency ope. rating mode. Therefore this occurrer.ce is considered an invalid failure of the SDG unit. ,

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9A007B 9306280195 930618 PDR ADDCK 05000416

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,a June 18, 1993 j GNRO-93/00075

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Yours truly,f  !

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f/ g!/U. f' l 4')f ;& # U

! CRH/RR/

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j_ cc: Mr. R. H. Bernhard 4

Mr. H. W. Keiser 3 Mr. R. '

B. McGehee

Mr. N. S. Reynolds i Mr. H. L. Thomas i

4 s

i Mr. Stewart D. Ebneter j Regional Administrator i U.S. Nuclear Regulatory Commission

Region II '

! 101 Marietta St., N.W., Suite 2900 Atlanta, Georgia 30323 4

j Mr. P. W. O'Connor (w/2)

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

{ Mail Stop 13H3 4

Washington, D.C. 20555 l

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