ML18096A408

Responds to Suppl 4 to Generic Ltr 88-20, Individual Plant Exam of External Events for Severe Accident Vulnerabilities. Seismic Analyses Will Employ Both Lasl & EPRI Hazard Curves

ML18096A408
Person / Time
Site:	Salem, Hope Creek
Issue date:	12/19/1991
From:	Miltenberger S Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-88-20, NLR-91207, NUDOCS 9201060186
Download: ML18096A408 (7)

Text

Public Service Electric and Gas Company Steven E. Miltenberger Public Service Electric and Gas Company P.O. Box 236, Hancocks Bridge, NJ 08038 609-339-1100 Vice President and Chief Nuclear Officer DEC 1 9 1991 NLR-N91207 U. s. Nuclear Regulatory Commission Document Control Desk Washington, D. C. 20555 Gentlemen:

GENERIC LETTER (GL) 88-20, SUPPLEMENT 04 INDIVIDUAL PLANT EXAMINATION OF EXTERNAL EVENTS (IPEEE) ; MILESTONES AND SCHEDULE SALEM AND HOPE CREEK GENERATING STATIONS DOCKET NOS. 50-272, 50-311, AND 50-354 In response to your letter dated June 28, 1991, Public Service Electric and Gas Company (PSE&G) hereby provides a description of its proposed program for completion of an IPEEE for severe accident vulnerabilities as requested by GL 88-20, Supplement 4.

The enclosure to this submittal details the methods and approach as well as the milestones and schedule to accomplish completion of the IPEEE analysis for the Salem units and Hope Creek. We intend to pursue this effort with vigor and involve our staff to the maximum extent possible while utilizing independent peer review by staff members who have not directly participated in the evaluation. PSE&G recognizes that the key outcome of this effort will be the knowledge and appropriate improvements resulting from the examination. Please contact us if you have any question regarding this transmittal.

Sincerely, Enclosure

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Document Control Desk 2 DEC 1 g 1991 NLR-N91207 c Mr. T. Martin, Administrator Region I Mr. T. Johnson Senior Resident Inspector Mr. s. Dembek Project Manager - Hope Creek Mr. J. Stone Project Manager - Salem Mr. K. Tosch, Chief New Jersey Department of Environmental Protection Division of Environmental Quality Bureau of Nuclear Engineering CN 415 Trenton, NJ 08625

REF: NLR-N91207 STATE OF NEW JERSEY SS.

COUNTY OF SALEM S. E. Miltenberger, being duly sworn according to law deposes and says:

I am Vice President and Chief Nuclear Officer of Public Service Electric and Gas Company, and as such, I find the matters set forth in our letter dated DEC 1 g 1991 , concerning the Salem Unit Nos. 1 and 2 and Hope Creek Generating Station are true to the best of my knowledge, information and belief.

Subscribed and Sworn to before me this \qr" day of ])ec..er'l !:.er- , 1991

_Notary-Public of New Jersey My commission expires on \S. \914 UNDA n. VREELAND Notary Public of New Jersey .

My Commission Expires Feb. 15, 1994

ENCLOSURE NLR-N91207 RESPONSE TO NRC GENERIC LETTER 88-20, SUPPLEMENT 4 SALEM UNITS 1 AND 2 AND HOPE CREEK GENERATING STATION DOCKET NOS. 50-272, 50-311, AND 50-354 SCOPE PSE&G intends to investigate the five external hazards identified in Section 3 of Generic Letter 88-20, Supplement 4. The scope of this investigation will subsume USI A-45 to the extent that the IPEEEs will include assessment of the adequacy of the decay heat removal system with respect to the external hazards. The scope will also subsume GI 131 for Salem 1 and 2 through investigation of the potential for instrumentation tube rupture at the seal table indirectly owing to earthquake induced failure of the flux mapping cart. In addition, PSE&G intends to resolve the Eastern U.S. Seismicity issue with respect to Salem and Hope Creek by the performance of the IPEEEs.

METHODS AND APPROACH In order to pursue the full benefits of performing an IPEEE for the future needs of severe accident management and the current needs of plant operation decision making, PSE&G will perform the IPEEE investigations using state-of-the-art Level 1 Probabilistic -

Risk Assessment (PRA) techniques. PSE&G is cognizant of NUREG/CR-5088, "Fire Risk Scoping Study," and will include the issues of control system interaction, seismic induced fires, fire barrier effectiveness, manual fire fighting effectiveness, and the effects of fire suppressants on safety equipment within the fire and seismic walkdowns and evaluations. In addition, containment performance investigation pursuant to NUREG-1407 will be performed.

SEISMIC EVENTS Salem and Hope Creek seismic analyses will employ both the LLNL and EPRI hazard curves. Seismic walkdowns will be coordinated with upcoming plant refueling outages in order to gain access to containment systems and structures and more easily follow the guidance in EPRI NP-6041. Components and structures for fragility analyses will be identified from the internal events IPE analyses which includes containment systems. Passive components and structures that could potentially contribute to earthquake induced core melt sequences will be added to these lists. The potential for liquefaction and its effects, and consideration of soil-structure interactions will be included in the PRAs. Fragility analyses for all identified components and structures will be performed in accordance with PRA practice as described in NUREG/CR-2300.

ENCLOSURE (cont'd)

Earthquake induced initiating events will be identified, and the systems analyses will employ internal events, event tree and fault tree models to assess the effect of concurrent nonseismic component failures and human interactions. Significant scenarios will be identified and core melt frequencies will be calculated.

If necessary, risk reduction strategies will be identified.

The walkdown and evaluation will attempt to identify containment failure modes, such as bypass or isolation events, that are different from those identified in the internal event IPE investigations. The fragility and system analyses will account for the effect of containment system success and failure.

INTERNAL FIRES The Salem and Hope Creek fire PRAs will take advantage of recent developments in the areas of fire database development, fire area screening criteria, and screening methods. The PRAs will include cable initiated fires, panel initiated fires, and transient combustible initiated fires. The concept of successive levels of qualitative and quantitative screening, which was used in several past PRAs, as well as the FIVE methodology, will be employed to identify significant fire areas. The significant fire areas of each plant that cannot be screened out will be evaluated by a PRA to identify significant core melt sequences, core melt frequencies, and , if necessary, risk reduction strategies. Fire induced initiating events will be identified and the internal events, event tree and fault tree models will be used to include non-fire component failures and human interactions.

Identification of fire areas and fire barriers will benefit from the information generated by Fire Hazard Analyses performed for compliance with 10CFR50, Appendix R. Area fire frequencies will be generated using both generic and plant specific databases.

Automatic and manual fire suppression will be included as counterpoint to the potential of fires to spread to more than one

'electrical division. A fire walkdown will'verify information used in the analyses, address the NUREG/CR-5088 issues, and attempt to identify containment failure modes that are different from those identified in the internal event IPE investigations.

ENCLOSURE (cont'd)

HIGH WINDS, TORNADOES, EXTERNAL FLOODS, TRANSPORTATION AND NEARBY FACILITY ACCIDENTS PSE&G finds the progressive levels of screening approach suggested in NUREG-1407 a reasonable way to emphasize effort in those external events that may require risk reduction strategies.

The scope of assessment for other external events will include hazards from high winds and tornadoes, external floods, and transportation and nearby facility accidents.

We currently believe that Hope Creek meets the 1975 Standard Review Plan criteria. Therefore, only confirmatory walkdowns are anticipated at this time. However, if the walkdowns reveal elements of the plant or offsite facilities not included in the design basis, then a progressive screening investigation will be performed.

Salem and Hope Creek share the same site so that hazards posed by transportation and nearby facilities are essentially identical.

External floods and windstorm hazards, however, may pose different risks to the Salem units than to Hope Creek. A screening analysis will be performed for Salem (up to a PRA, if necessary) to assess the risk posed by these two hazards and, if needed, to identify risk reduction strategies.

EVALUATION OF RISK REDUCTION STRATEGIES Because the identification of risk reduction strategies resulting from the IPE, if any, will be made before insights from the IPEEE are available, PSE&G intends to revisit the IPE developed strategies as part of the IPEEE. This will allow us 1) to ensure that the IPE generated risk reduction strategies do not generate vulnerabilities with respect to external events, 2) to ensure that IPEEE generated strategies do not detract from the benefit of IPE generated strategies, and 3) generate and evaluate cost effective strategies that reduce the risk of both internal and external events.

MILESTONES AND SCHEDULE The Salem and Hope Creek IPEEEs will proceed essentially in parallel. The following milestones and schedule were selected to take advantage of the refueling outage schedules. It also provides for involvement of our staff and allows ample time for peer review of the analysis as well as management review of proposed risk reduction strategies. The significant milestones and schedule are as follows:

ENCLOSURE (cont'd)

MILESTONES March 31, 1993 Complete Planning and Vendor Selection Process December 30, 1994 Complete Peer Review, Final Assessments, Proposed Risk Reduction Strategies, and Tier 2 Documentation May 30, 1995 PSE&G Management Approval, Complete Tier 1 Documentation, and submit results to the NRC