ML17252A458

Submittal of Licensee Event Report 01X-1 Concerning a Potential Problem Postulated with the Designed Logic System

ML17252A458
Person / Time
Site:	Dresden
Issue date:	08/28/1978
From:	Stephenson B Commonwealth Edison Co
To:	James Keppler NRC/RGN-III
References
LER 01X-1
Download: ML17252A458 (3)

Text

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Commonwea9Edison Dresden Nuclear Power Station R.R. #1 Morris, Illinois 60450 Telephone 815/942-2920

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(fl 01 BBS LTR //78::-1223 James G. Keppler, Regional Director Directorate of Regulatory Operations - RegioneTII U.S. Nuclear Regulatory Conimission 799 Roosevelt Road Glen Ellyn, IL 60137 Reportable Occurrence "Update Report" /178-017 /OlX-1, Docket 11

• being submitted to your office to correct the Cause Code and

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Subcode (Items 12 and 13) used in the original Licensee Event Report 78-017/0lT-0. The report concerned a potential problemwhichhad been postulated with the designed logic system.

Only it.ems (12) & (13) on the or~ginal report form have been reclassified to indica.te a design error. No ot!ier changes have be~n made; This event was reported to you under Dresden Nuclear Power Station Technical Specification 6 .. 6.B. l.. (i), performance of structures, systems, or com-ponents-that requires remedial action or corrective measures to prevent operation in a manner less conservative than .assumed in the a.ccident analyses in the safety analysis report or technical specifications bases; or discovery during plant life of conditions not specifically considered in -the safety analysis report or technical specifications that require remedial action or corrective measures to prevent the existence or development. of an unsafe*'tcondition.

ph n Station Superintendent Dresden Nuclear Power Station BBS/deb Enclosure cc: Director of Inspection & Enforcement Director of Management Information & Program Control Fiie/NRC AUG 31 1978

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*' ' .;e LICENSEE EVENT REPORT U.S. NUCLEAR REGULATORY COMMISS1t1l\I' .

Updl Report Previous**

Rep. Date:. 5/5/7S .* ,.,.

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[]]IJ I During normal Unit 2 operation and routine Unit 3 refueling operations on April 21, *I*

mIJ I 197S. the NRC requested immediate actions be taken to mitigate the potential for a

[Q]I) I spurious closure-of a recircuiation loop suction valve~ This situation has not been L

[I]}]. I previously analyzed and. is reportable. per. section 6. 6 .. B. 1. ( i) of the Technical J

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(J]2J I On April 21, 197S,. to comply with the NRC request a Mod. was initiated for each unit J.

[I]JJ 1which will defeat that portion of the LPCI Loop Select Logic which auto closes the

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This Mod. is presently pending SNED approval.. As an interim* solution I

• .IT]]] I suction valves.

TJJ]J I both recirc .. loop .suction valve circuit breakers will. be taken 0.0.S. in the open 1*

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• ,'t'. ATTACHHENT TO LICENSEE EVENT REPORT 78-017/0lX-l .

COMMONWEALTH EDISON COJ:.-IPANY (CHE)

DRESDEN UNIT-3 (ILDRS-3)

DOCKET !los0-249 During normal Unit 2 operation at 820MWe and routine Unit 3 refueling operations on April 21, 1978, the Nuclear Regulatory Commission (NRC) requested that adequate action be taken immediately to mitigate the po-tential for a spurious closure of a recirculation Loop Suction Valve with a LOCA occurring between the 1,oop discharge and suction valves. This situation, which had not been considered inthe current LOCA analysis, could decrease the reactor water inventory while reactor pressure remained high. Technical Specification 6.6.B.l.(i) requires reporting of performance of structures, systems, or ~omponents that require~ remedial action or corrective measures to prevent operation in a manner less ~onservative than assumed in the accident analyses in the safety analysis report or technical specifications bases; or discovery during plant life of ronditions not specifically considered in the safety analysis report or technical specifications that require remedial action or corrective measures to

• *. prevent the existence or development of an unsafe condition. . ..

On April 21, 1978, to comply with the above NRC request,-~ modification was initiated for each unit. The modification., will. defeat only that portion of the Low Pressure Coolant In.i~*~ttq*p:-__ (LPCI) "Lo-op Select Logic-wh1ch automatically closes the recirculation loop sucti.Cin valves:* The.. Station.****.

Nuclear Engineering Department (SNED) :is currently reviewing the modifi-:-

cation., The Unit 3 modificati~n will not be* completed until a later unit outage of sufficient duration occurs. following SNED approval. As an in-

• terim solution, both recirculation loop suction valve circuit breakers will

. * ....... *be taken out~of-service with the valves in the open position. While in

• • this condition the LPCI System will continue to function as orl.ginally. *

':**; .. analyzed. Operation of the suction valves will be permitted per operating order #27-78 if an operational event occurs which requires the suction

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• valve .to be Cle>sed. In this case both the loop d~scharge valve and discharge

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• bypass valve will also be closed thereby isolating the recirculation . _. . , . < _ :-...

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