ML20236H458
| ML20236H458 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 07/31/1987 |
| From: | Gallagher J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Butler W NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM), Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8708050199 | |
| Download: ML20236H458 (5) | |
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PHILADELPHIA ELECTRIC COMPANY i
2301 MARKET STREET P.O. BOX 8699 PHILADELPHIA A. PA.19101 (215) e415ool JOSEPH W.GALLAGHER vic e p.s seDs NT July 31, 1987 v e s... - s......
J Mr. Walter R. Butler, Director Docket No.:
50-352 Project Directorate I-2 Division of Reactor Projects I/II U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
Subject:
Limerick Generating Station, Unit 1 Justification for Continued Operation i
Residual Heat Removal Service Water Process Radiation Monitors (RHRSW PRM)
Reference:
Letter from J. S. Kemper (PECo) to A. Schwencer (NRC), dated September 6, 1984
Attachment:
Limerick Generating Station, Unit 1 Justification for Continued Operation l
Files GOVT l-1 (NRC)
Dear Mr. Butler:
The referenced letter transmitted our Justification for Interim Operation (JIO) for Limerick Unit 1, until the first refueling outage, pendirg confirmation of the dynamic qualification of the residual heat removal service water process radiation monitors (RHRSW PRMs).
Since the submittal of that JIO, however, the manufacturer has concluded that the qualification test records could not be located to satisfy the requirement of the JIO.
As an alternate, therefore, qualified, Class lE, replacement radiation monitors were purchased for installation into the RHRSW system during the first (current) refueling outage.
To date, two of the four existing RHRSW PRMs have been replaced.
However, satisfactory performance has not been demonstrated by either replacement.
Our engineering and technical staffs have worked dili-gently with the manufacturer for several months, but are unable to provide an on-site resolution to the hardware failures, hardware and software deficiencies, and unexplained operating anomalies in time to support the scheduled restart of Limerick Unit 1.
We have evaluated the continued use of the existing RHRSW PRMs, and have concluded that the existing equipment provides the highest degree of protection to the public health and safety.
The attached document, therefore, provides the justification for the continued operation of Limerick 1h ph(h 52 PDR 1
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Mr. Walter R. Butler July 31, 1987 Project Directorate I-2 U.S. Nuclear Regulatory Commission i
Generating Station, Unit'1, using the existing RHRSW PRMs, pending I
satisfactory rework of the replacement radiation monitors by the manu-facturer.
Philadelphia Electric Company will continue to expedite this rework, and will have qualified RHRSW PRMs in-service by the end of the second refueling outage, Limerick Unit 1 is presently scheduled for restart on August.15, l
o 1987.
We therefore respectfully request your expedient review and approval of this justification.
In.accordance with Section 170.12 of 3
the Commissions's regulations, enclosed is Philadelphia Electric Company's check in the amount of $150.00 to cover the filing fee.
Should you require any additional information, please do not hesitate to call us.
Sincerely, do,i $ 6 L RCW:ssh Attachment Enclosure Copy to: Addressee l
Regional Administrator U.S. Nuclear Regulatory i
l Commission, Region I Mr. E. M. Kelly Senior Resident Inspector 1
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i LIMERICK GENERATING STATION, UNIT I JUSTIFICATION FOR CONTINUED OPERATION j
i Limerick Generating Station, Unit 1, has been operating under a j
Justification for Interim Operation (JIO) that was accepted by the Nuclear Regulatory Commission in Supplement No. 3 of NUREG-0991:
Safety Evaluation Report Related to the Operation of Limerick Generating Station, Units 1 and 2 (SSER-3, Section 3.10.1).
This JIO presented justification for operating Licerick Unit 1, until the first refueling i
outage, pending confirmation of the dynamic qualification of the Log Count Rate Meters (LCRMs) associated with the Residual Heat Removal Service Water Process Radiation Monitors (RHRSW PRMs).
Since submittal of the JIO, however, correspondence with the LCRM manufacturer (General Electric Company) has concluded that "...while there is strong evidence that the LCRM was qualified by test (seismic bracing added to the Limerick model LCRM) qualification test records cannot be located..." to satisfy the requirements of the JIO.
As an acceptable solution, therefore, qualified, Class lE, replacement LCRMs were purchased from General Electric Company for installation during the first refueling outage.
To date, however, only two of the four existing LCRMs have been replaced, and satisfactory performance has not been obtained from the replacement LCRMs.
Our engineering and technical staff have been working diligently with the manufacturer for several months, but are unable to satisfactorily resolve on-site hardware failures, hardware and softwcre deficiencies, and unexplained operating anomalies in time to support restart of Limerick Unit 1.
We have evaluated the continued use of the existing RHRSW PRMs, and have concluded that the existing equipment provides the highest degree of protection to the public health and safety.
This document, therefore, provides the justifica-tion for the continued operation of Limerick Generating Station, Urit 1, through the second refueling outage, using the existing RHRSW LCRMs pending satisfactory rework of the replacement LCRMs by General Elec-tric Company.
The RHRSW PRM detects high radiation levels in the cooling water effluent (RHRSW) from the RHR heat exchangers in case of a heat exchanger tube leak of radioactive reactor coolant or suppression pool water to the RHRSW system. The effluent RHRSW is routed to the cooling towers (normal) or the spray pond (accident).
There are redundant RHRSW PRMs on each RHRSW release path.
The RHR heat exchanger discharge is monitored by a RHRSW PRM which isolates the heat exchanger discharge.
In addition, the RHR loop discharge header is monitored by a RHRSW PRM which shuts off the applicable RHRSW pump.
The heat exchanger discharge, and the loop discharge RHRSW PRMs are supplied by different divisions of Class lE power.
Therefore, a single failure of one division of Class lE power will not result in an unmonitored release from RHRSW.
The RHESW PRM consists of a remote sampling station (liquid sample rack / scintillation detector) located in the area of the diesel generators and a log count rate meter (LCRM) located in the auxiliary equipment room, plus alarm and trip instrumentation. Dynamic
LGS, Unit 1
all of this equipment except for the LCRM.
There is strong evidence j
that the LCRM was qualified by test (seismic bracing was added to the I
Limerick model LCRM); however, the qualification test records are not available.
The justification for continued operation of Limerick Unit 1 (essentially identical to the justification for interim operation) is as follows:
1.
Since the RHRSW PRM is not required to be active safety-related (i.e., not required to mitigate the consequences of a resign Basis Accident) the only safety concern is the potential effect of the LCRM failure on either the class 1E power circuits or the operation of the safety-related RHRSW system.
'Jtems 2,
3, and 4 below address the possible effects of a LCRM failure.
2.
All class 1E power circuits are redundant and separated, hence a single LCRM failure that causes a class lE power circuit failure is within the Limerick Design Basis (i. e.
failure of a single, active, safety-related component).
3.
There are two RHR heat exchangers, each with its own RHRSW supply system.
Hence, shutdown and isolation of one RHRSW supply system because of a PRM component failure is within the Limerick Design Basis (i.e., failure of a single safety-related component).
4.
If the shutdown and isolation of one, or both, RHRSW supply systems results from false high radiation 12 Vel PRM trip signals, the operator can manually bypass the signals and reopen the RHRSW isolation valves and restart the RHRSW supply pump (s).
The operator can determine if the trip is due to a false high radiation level trip signal, because there are two PRMs on the RHRSW supply system for each RHR heat exchanger.
5.
Both RHR heat exchangers are seismically qualified, therefore, a safe shutdown earthquake would not cause a heat exchanger tube failure.
Consequently, the RHRSW PRMs would not be required for safety-related service because there would not be any heat exchanger tube leakage into the RHRSW system.
6.
All of the RHRSW PRM components are located in mild environment areas (auxiliary control room and diesel generator areas) where hydrodynamic loads are minor or nonexistent.
All of the components have been qualified, except the LCRM, for which there is-strong evidence of qualification.
Consequently, PRM component failure is not likely.
-LGS, Unit 1
Because of the qualification level of the RHRSW PRM components, the occurrence of multiple failures has a very low probability.
I For. the reasons outlined above, it is believed that the probability of a system. failure associated with the LCRM is low enough to justify the safe continued operation of Limerick Unit 1.
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