ML20214G523
| ML20214G523 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 11/17/1986 |
| From: | Kemper J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| CON-#486-1651 IEB-86-003, IEB-86-3, OL, NUDOCS 8611260124 | |
| Download: ML20214G523 (6) | |
Text
IN EtlATED CO?IRESPONDENg PHILADEL'PHIA ELECTRIC COMPANY occgtito u91Rc 23O1 M ARKET STREET P O F3OX 8699
'86 NOV 25 All :08 PHILADELPHI A. PA.19101 JOHN S. KEMPER
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' R *e November 17, 1986 9.
OnnVCT NUMBER f t) Q Q d L-
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Docket No. 50-353 C L-Dr. T. E. Murley, Administrator Region I U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406
SUBJECT:
Limerick Generating Station Unit 2 Response to IE Compliance Bulletin 86-03: Potential
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Failure of Multiple ECCS Pumps Due to Single Failure of Air-operated Valves in Minimum Flow Recirculation Line
REFERENCE:
IE Compliance Bulletin 86-03: Potential Failure of Multiple ECCS Pumps Due to Single Failure of Air-operated Valves in Minimum Flow Recirculation Line, dated October 8, 1986 FILE:
GOVT l-1 (URC)
Dear Dr. Murley:
The purpose of this letter is to provide the Philadelphia Electric Company (PECo) response to IE Compliance Bulletin 86-03 for Limerick Generating Station Unit 2.
The bulletin discusses a situation at four operating nuclear power plants in which a single failure occurring under certain accident sequences could result in the loss of multiple Emergency Core Cooling System (ECCS) trains.
The postulated single failure involves the failure of a minimum flow recirculation line shut-off valve causing the valve to go closed and remain closed.
As indicated in the bulletin, this condition could lead to multiple ECCS pumps running dead headed with the potential for pump damage and failure in a few minutes.
Multiple pump failure could disable mere I
than one train of ECCS.
The actions required by the bulletin are restated below followed by our response:
8611260124 861117 PDR ADOCK 05000352 PDR bso3
1.
Promptly determine whether or not your tacility has a single failure vulnerability in the minimum flow recirculation line of any ECCS pumps that could cause a failure cf more than one ECCS train.
2.
If the problem exists: (a) promptly instruct all operating shifts' of the problem and measures to recognize and mitigate the problem; (b) promptly develop and implement corrective actions which bring your facility into compliance with GDC 35.
3.
Within 30 days of receipt of this bulletin, (a) provide a written report to the NRC which identifies whether or not this problem - exists at your facility, (b) if the problem I
exists - (or existed), include in the report the justification for continued operation and identify the short-term mcdifications to plant operating procedures or hardware that have been or are being Jeplemented to ensure safe plant operations.
4.
If the problem exists (o'r existed), provide a written report within 90 days of receipt of thi.s bulletin informing the NRC of the schedule for long-term resolution of this and/or any other significant problems that are identified as a result of thic Lulletin.
RESPONSE
PECo has reviewed the ECCS and RCIC minimum flow recirculation design for Limerick Generating Station Unit 2 and has determined that a single failure vulnerability in the minimum flow recirculation line of any ECCS or RCIC pump that could cause a failure of nore than one ECCS train does not exist at Limerick Generating Station Unit 2.
All of the minimum flow recirculation line shut-off valves for the RHR, Core Spray, HPCI and RCIC pumps are motor operated valves.
The HPCI, RCIC, each of the four trains (loops) of RHR, and each of the two trains (loops) of Core Spray have their own ' dedicated minimum flow return line to the suppression pool with a motor operated shut-off valve in each return line, and a flow sensing instrument loop installed in the discharge line of that train to control the position of the minimum flow recirculation line shut-off valve. Each train of RHR contains one 100% loop flow capacity pump and each train of Core Spray contains two 50% loop flow capacity pumps.
Each train of RHR is assigned to a different electrical safeguard division and as such each train is redundant to, independent of, and separated from the other trains of RER.
Likewise, each train of Core Spray is assigned to two different electrical safeguard divisions, and as such each train is redundant to, independent of, and separated from the other train of l
The HPCI and RCIC systems are dependent on the plant DC pcwer supplies only. The pump, minimum flow recirculation line shut-off valve, and the discharge line flow sensor, for HPCI, RCIC and each train of RHR and Core Spray and the electrical safeguard divisions which they are assigned to are provided in Table 1.
-There is no single failure identified which will result in the failure of an ECCS or RCIC minimum flow recirculation line that will result in the loss of more than one train of ECCS.
However, a single failure that would disable more than one ECCS or RCIC system minimum flow recirculation line would be the loss of one of the AC electrical safeguard diyision motor control centers.
This single failure would disable one RHR and one Core Spray minimum flow recirculation line shut-off valve.
If the disabled valves were closed at the time of the single failure, the associated trains of RHR and Core Spray could be lost.
The HPCI, RCIC, each of the three remaining trains of RHR and the remaining train of Core Spray would not be affected.
The loss of one of the AC electrical safeguard division motor control centers is enveloped by the loss of one diesel generator along with ita associated safeguard bus, i.e.,
the loss of one AC electrical safeguard division. - This event has previously been analyzed as part cf the plant's design basis in FSAR Section 8.3.1.
A single failure vulnerability in the minimum flow recirculation line of any ECCS or PCIC pump that could cause a failure of more than one ECCS train as discussed in IE Compliance Bulletin 86-03 does not exist 'at Limerick Generating Station Unit 2.
There is no identified single failure of one ECCS or RCIC minimum flow recirculation line that will' disable more thar. One train of ECCS or RCIC.
No 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.
Very truly yours, M
RTG/sjf/1148602 Attachment Copy to:
(See attached Service List) e t
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TADLU 1 Ar FLFCfRICAL sal'CGifARD DTV3SION ASSIGN?iFNTS, ECCS MIN. FLOW DISCH. LINE SAFEGUARD TRAIN PUMP RECIRC. VALVE--
FLOW SENSOR DIVISION A RHR 2AP202 HV-51-2F007A PT-51-2N052A Division I B RHR 2BP202 HV-51-2F007B FT-51-2N052B Division II C RiiR 2CP202-EV-51-2F007C FT-51-2N052C Division III
.D RHR 2DP202.
HV-51-2F007D FT-51-2N052D Division IV I
A Core Spray 2AP206 HV-52-2F031A FT-52-2N051A Division I j
2CP206 Division III B Core Spray 2BP206 HV-52-2F031B FT-52-2N051B Division II 2DP20C Division IV DC ELECTRICAL SAFEGUARD DIVISION ASSIGNMENTS ECCS/RCIC MIN. FLOW DISCH. LINE SAFEGUARD TRAIN PUMP RECIRC. VALVE FLOW SENSOR DIVISION f
HPCI 20P204 HV-55-2F012 FT-55-2N051 Division II RCIC 20P203 HV-49-2F019 FT-49-2N051 Division I t-i I
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COUNTY-OF filILADELPHIA J. S. KEMPER, being first duly sworn, deposes and says:
That he is Vice President of the Philadelphia Electric Company; that he has read the foregoing response to I.E.Bulletin 86-03 and knows the contents thereof; and that the statements and matters set forth therein are true and correct to the best of his knowledge, Infonmtion and belief
[W4 Vig President /
E6gineering & Research Subscribed and sworn to before me this [ [ 7 day of p
, 1986
/*
tbtary Public
[
MELANIE R. CAMPANELLA Notary Public, Phtbdelphia. Philadciphia Co.
My Commission bpres FaNusry 12. 1990
cc: Troy B. Conner, Jr., Esq.
t i imi ti !!. Voc1"r, Esq.
- a. ihdeert i.. Antianiy
- 13. '.Liureen ShilIigati Charles W. Elliott, Esq.
Barry M. Ilartman, 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 6 Licensing Appeal Boaro Atomic Safety 6 Licensing Board Panel Docket 6 Service Section E. M. Kelly i
Timothy R. S. Campbell 1
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