05000416/LER-1983-188, Updated LER 83-188/03X-1:on 831201,reactor Protection Sys Bus B & Shutdown Cooling Lost When Power Supply Breaker Tripped.Caused by Isolation Valve on Suction of Pump Closing.Time Delay Setting Increased to 3.5 s.W/840321 Ltr

Updated LER 83-188/03X-1:on 831201,reactor Protection Sys Bus B & Shutdown Cooling Lost When Power Supply Breaker Tripped.Caused by Isolation Valve on Suction of Pump Closing.Time Delay Setting Increased to 3.5 s.W/840321 Ltr

ML20087M626
Person / Time
Site:	Grand Gulf
Issue date:	03/21/1984
From:	Byrd R, Dale L MISSISSIPPI POWER & LIGHT CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
AECM-84-0171, AECM-84-171, LER-83-188-03X, LER-83-188-3X, NUDOCS 8403300117
Download: ML20087M626 (3)

LER-2083-188, Updated LER 83-188/03X-1:on 831201,reactor Protection Sys Bus B & Shutdown Cooling Lost When Power Supply Breaker Tripped.Caused by Isolation Valve on Suction of Pump Closing.Time Delay Setting Increased to 3.5 s.W/840321 Ltr

Event date:
Report date:
4162083188R00 - NRC Website

text

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EVENT DESCRIPTION afeD Wm E CONSEQUENCES h

.. W ion December 1. 1983. a loss of RPS Bus "B" and shutdown coolina occurredt o 3 [when the alternate power supply breaker tripped. The loss of shutdown j io l41 koolina was caused by an isolation valve on the suction of the pump i g iclosing. Part of the valve's isolation logic is powered from the RPS l

@ lkus . Power was transferred to the RPS motor generator set and shutdown i

@ (coolina was restored within one hour as required by T.S.3.4.9.2. This  !

@ li s submitted pursuant to T.S.6.9.1.13.b as a final report. I t ee so C ODE "' aran 8 CE.eose TCODE e b Q s l ElBl h W h W h IC]Kl TlBl RIKe h A@

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j d6] (Voltage transients on the RPS bus have caused several RPS breaker trips l Q] f (See LER 83-137 & LER 84-002) . To prevent trips on short transients, thel

, , 2 gtime delay settings for the breakers have been increased from O.1 sec- 3

, 3 jonds to 3.5 seconds. Additional enhancements being performed such as an l g [ increased range for trip setpoints are discussed in LER 84-002. j

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E MISSISSIPPI POWER & LIGHT COMPANY Helping Build Mississippi P. O. B OX 164 0. J A C K S O N. MI S SIS SIP PI 3 9 2 0 5 AfD ' 19 34 MAR 20March Zl,1984 NUCLE AR PRODUCTION DEPARTMENT U.S. Nucicar Regulatory Commission Region II 101 Marietta St., N.W., Suite 2900 Atlanta, Georgia 30303 Attention: Mr. J. P. O'Reilly, Regional Administrator near Mr. O'Reilly:

SUBJECT:

Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License No. NPF-13 File: 0260/L-835.0 Update Report - Loss of RPS Bus "B" and Shutdown Cooling LER 83-188/03 X-1 ~

AECM-84/0171 This letter submits an update to a previous report submitted on December 30, 1983. The event for which the report was submitted occurred on December 1, 1983, when a loss of RPS Bus "B" and shutdown cooling occurred when the alternate power supply breaker tripped. Power was transferred to the RPS motor generator set and shutdown cooling was restored within one hour as required by Technical Specification 3.4.9.2. This was reported pursuant to Technical Specification 6.9.1.13.b.

Our investigation into the cause of the event is complete. Corrective action to prevent RPS breaker trips on short voltage transients has been implemented. Additional enhancements being performed are discussed in LER 84-002. Attached is LER 83-188/03 X-1 which is a final report.

Yours truly, L. F. Dale Manager of Nuclear Services EBS/SHH:rg Attachment cc: See next page OFFICIALCOPY 5,5Z T_

l Member Middle South Utilities System 1 (

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AECM-84/0171 MISSISSIPPI POWER Q Ll2HT COMPANY i

cc: Mr. J. B. Richard (w/a)

Mr. R. B. McGehee (w/o)

Mr. T. B. Conner (w/o)

Mr. G. B. Taylor (w/o)

Mr. Richard C. DeYoung Director (w/a)

< Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission

Washington, D. C. 20555 Document Control Desk (w/a) i U. S. Nuclear Regulatory Commission ,

Washington, D. C. 20555 I

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