ML18100A508
| ML18100A508 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 07/30/1993 |
| From: | Labruna S Public Service Enterprise Group |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML18100A509 | List: |
| References | |
| GL-88-20, NLR-N93109, NUDOCS 9308060186 | |
| Download: ML18100A508 (4) | |
Text
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Public Service Electric and Gas Company I
Stanley LaBruna Public Service Electric and Gas/Company P.O. Box 236, Hancocks Bridge, NJ 08038 609-339-1700 Vice President - Nuclear Engineering JUL 3 0 1993 NLR-N93109 United States Nuclear Regulatory Commission Document Control Desk Washington, D.C.
20555 Gentlemen:
GENERIC LETTER 88-20; INDIVIDUAL PLANT EXAMINATION (IPE) REPORT SALEM GENERATING STATION UNIT NOS. 1 AND 2 DOCKET NOS. 50-272 AND 50-311 This letter forwards the Salem Generating Station (SGS) IPE Report as Attachment 1, including final assessments and recommendations.
The SGS IPE yi~lded a Core Damage Frequency (CDF) of 4.5 E-5/yr for Unit 1 and 4.8 E-5/yr for Unit 2.
These values compare favorably with the NUREG-1150 reference plant Zion (3.4 E-5/yr).
The Internal Flooding CDF for each Salem Unit is
- 7. 3 E-6/yr.
No internal event outliers were identified for either Salem Unit.
Two vulnerabilities were identified during the Internal Flooding and Containment Bypass Analyses.
The first involves an internal flooding potential due to eyewash lines in the Relay and Switchgear Rooms.
The SGS IPE recommended a design change to reduce this impact.
Subsequent IPE reviews and field walkdowns have identified existing room floor drains previously unaccounted for in tpe IPE analyses.
These floor drains reduced each unit's Internal Flood initiating event frequency from 1.5 E-5 to 7.3 E-6.
They also decreased the large early direct (Release Category Group I) total frequency from 3.95 E-6 to 3.09 E-6.
The IPE recommended design change is no longer valid.
However, due to the printing time associated with this voluminous report, Public Service Electric and Gas Company (PSE&G) was unable to update the IPE report prior to submittal.
The second vulnerability concerns an apparent procedural weakness for isolating certain Inter-System Loss of Coolant Accidents (ISLOCA).
The SGS Residual Heat Removal (RHR) System contains pressure relief valves that discharge to the Pressurizer Relief Tank (PRT) located inside containment.
A PRT overpressure condition results in rupture disc blowout, with subsequent water release to the containment environment.
An ISLOCA between the Reactor Coolant system and RHR System will result in RHR pressure relief to the PRT, and ultimately the containment.
9308~60186 930730 PDR -ADOCK 05000272 p
i Document Control Desk NLR-N93109 2
JUL 3 o 1993 SGS Emergency Operating Procedures (EOPs) follow the Westinghouse Owners Group (WOG) Emergency Response Guidelines (ERGs), which check for LOCAs inside containment before considering possible outside containment LOCAs.
For plants like Salem where the RHR relief valves direct flow to the PRT, the symptoms will indicate a small LOCA upon PRT rupture disc blowout.
Operators may transition to the LOCA EOPs and never enter the LOCA outside containment EOP.
We investigated the benefit of a procedure change by conservatively assuming that operators make the transition with an error probability of 0.1.
This resulted in a V-Seq discharge frequency reduction from 5.1 E-7 to 5.1 E-8, and a CDF reduction of 1.01%.
The large early direct (Release category Group I) total frequency decreased to 3.79 E-6, which corresponds to a 4%
reduction.
Thus, the impact due to this procedural weakness is not significant.
This generic procedure weakness is common to Westinghouse PWRs.
PSE&G submitted a WOG ERG direct, work request on July 12, 1993, requesting evaluation and ERG revision as appropriate.
Any SGS EOP revisions would be based on updated WOG ERGs.
Should you have any questions on this transmittal, please contact us.
Sincerely, Attachment (1)
Document Control Desk NLR-N93109 3
C Mr. T. T. Martin, Administrator - Region I U. s. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 Mr. J. c. Stone, Licensing Project Manager -
Salem U. s. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Rockville, MD 20852 Mr. T. P. Johnson (S09)
USNRC Senior Resident Inspector Mr. K. Tosch, Manager, IV NJ Department of Environmental Protection Division of Environmental Quality Bureau of Nuclear Engineering CN 415 Trenton, NJ 08625 JUL 301993
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ATTACHMENT 1