ML20202G568

Responds to IE Bulletin 86-001, Min Flow Logic Problems That Could Disable RHR Pumps, for Unit 1.RHR Min Flow Logic Problem Does Not Exist at Plant.Related Correspondence

ML20202G568
Person / Time
Site:	Limerick
Issue date:	06/06/1986
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
CON-#386-654 IEB-86-001, IEB-86-1, OL, NUDOCS 8607160004
Download: ML20202G568 (5)

Text

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• June 9, #,s 9%r6/ t, A /' [,

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Docket No. g l,

Dr. T. E. Murley, Administrator ,

- < j Region I U.S. Nuclear Regulatory Commission ,

631 Park Avenue King of Prussia, PA 19406  !

Subject:

Response to IE Bulletin 86-01:

(Minimum Flow Logic Problems that could Disable RHR Pumps), Dated May 23, 1986 Limerick Generating Station Unit 1 Dear Dr. Murleys f

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The purpose of this letter is to provide the Philadelphia Electric Company (PECo) response to IE Bulletin !4 '

86-01 for Limerick Generating Station Unit 1. The bulletin discussed a situation at an operating nuclear power plant in which a single failure occurring under certain accident sequences could result in all Residual Heat Removal (RHR) system minimum flow bypass valves being signaled to close while all other pump discharge valves are also closed. The postulated single failure involves loss of a flow sensing instrument. As indicated in the bulletin, this condition could result in.no flow through the RHR pumps and could lead to the pumps running dead headed with potential for pump damage in a few minutes. The actions required by the bulletin are restated below followed by our response:

1. Promptly determine whether or not your facility has this single failure vulnerability. j

2. If the problem exists, immediately instruct all operating shifts of the problem and measures to  !

recognize and mitigate the problem. (,

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8607160004 860606 PDR O ADOCK 05000352' PDR i J-

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'Dr. T. E. Murley June 9, 1986 Page 2. .i i

3. Within 7 days of receipt of this bulletin, provide '

(a) a written report to the NRC which identifies l whether or not this problem exists at your  !

facility, (b) if the problem exists, identify the short-term modifications to plant operating El procedures or hardware that have been or are being L implemented to assure safe plant operation's.

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4. If the problem exists, provide a written report within 30 days of receipt of this bulletin informing the NRC of the. schedule for long-term resolution of problems'that are identified as a result of this bulletin. t l

Response

PEco has reviewed the RHR minimum flow logic for Limerick Generating Station Unit 1 and has determined that the single failure condition discussed in IE Bulletin 86-01 ,

does not exist at the unit. The RHR system is comprised of -

four independent and redundant electrical safeguard i

divisions. There are four RHR pumps; each pump has an associated flow sensing loop installed in the pump discharge j line~and an associated minimum flow return line to the ,

suppression pool. Each flow sensing loop consists of a flow

!' element, flow transmitter and flow indicating switch. A l normally closed motor operated shutoff valve is provided in i:

each minimum flow return line. Attachment 1 provides a list b of the subject pumps, valves, and flow sensing ,

instrumentation. ..

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When a RHR pump is operating, the associated flow sensing loop installed in the pump discharge line initiates automatic opening of the shutoff valve in the associated ,

minimum flow return line if adequate flow is not sensed in i the pump discharge line. When adequate flow is established,  ;

{ the flow sensing loop initiates automatic closure of the 1 1- shutoff valve. Each flow sensing loop controls only the  ;

j shutoff valve associated with that RHR pump and flow sensing i loop. l i;

! Each RHR pump, associated flow sensing ,

1 instrumentation, and associated minimum flow return line and +

!' shutoff valve is assigned to a separate electrical safeguard h

! division. Consequently, each pump, associated flow sensing >

L inst ~rumentation, and minimum flow return line and shutoff I i valve is independent from, separated from, and redundant to t' i

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Dr. T. E. Murley June 9, 1986 Page 3

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each of the other pumps and associated equipment. The -

single failure of a flow sensing element could result in the loss of only the associated RHR pump. The three remaining RHR pumps will not be affected.

The RHR minimum flow logid problem identified in ,

IE Bulletin 86-01 does not exist at Limerick Generating

' Station Unit 1. No long-term modifications to plant ,

operating procedures or hardware are required.

Should you have any questions, or require  ;

additional information, please do not hesitate to contact us.

f Very truly yours,  !

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Attachment -

cc: E. M. Kelly, Senior Resident Site Inspector i Document Control Desk i,

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ATTACHMENT 1 Bullotin 86-01 Recponse .

\ June 9, 1986 j Docket No. 50-352 .;

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RHR PUMP MINIMUM FLOW PROTECTION LIMERICK GENERATING STATION UNIT 1 RHR Pump Minimum Flow Valve Control Device .

l.AP202 HV-lF007A FM-IN014A FT-1.N052A i

FISL-IN652A ,

i' 1BP202- HV-1F007B FE-1N014B FT-IN052B l FISL-IN652B l ICP202 HV-lF007C FE-1N014C FT-lN052C FISL-IN652C 3 i LOP 202 HV-1F007D FE-lN014D  !

1 FT-lN052D ,

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cc: Troy B. Conner, Jr., Esq.

Ann P. Hodgdon, Esq.

Mr. Frank R. Romano Mr. Robert L. Anthony Ms. Phyllis Zitzer Charles W. Elliott, Esq. s Barry M. Hartman, Esq.

Mr. Thomas Gerusky Director, Penna. Emergency Management Agency Angus Love, Esq.

David Wersan, Esq.

Robert J. Sugarman, Esq.

Kathryn S. Lewis, Esq.

Spence W. Perry, Esq.

Jay M. Gutierrez, Esq.

Atomic Safety & Licensing Appeal Board Atomic Safety & Licensing Board Panel Docket & Service Section (3 Copies) ,

E. M. Kelly Timothy R. S. Campbell February 4, 1986

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