ML20211C558

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Forwards 840621 Memo Re Facility PRA Review & Site Visit. Objective of Site Visit & Type of Util Personnel to Discuss Specific Questions W/ Requested by 840817
ML20211C558
Person / Time
Site: Seabrook  NextEra Energy icon.png
Issue date: 08/16/1984
From: Davis S
Office of Nuclear Reactor Regulation
To: Nilesh Chokshi, Pichumani R, Sobel P
Office of Nuclear Reactor Regulation
Shared Package
ML20209C800 List:
References
FOIA-87-6 NUDOCS 8702200131
Download: ML20211C558 (2)
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l b AUG 161984 i NOTE T0: Those on Attached List FROM: Sarah M. Davis Reliability and Risk Assessment Branch, DST

SUBJECT:

. SEABROOK PRA REVIEW AND SITE VISIT Enclosed is the June 21, 1984 memo regarding the Seabrook PRA review, in case you did not receive a copy, as a reminder of the constraints and control which must accompany this limited review. Due to the circumstances surrounding the financial status of Public Service of New Hampshire and their voluntary submittal of a PRA, it is imperative to keep the scope of review in mind and the coordination required when formulating questions, providing the scope of work to contractors in some cases, and assessing the need for a site visit.

All questions and comments should be submitted to me, and in cooperation with the DL Project Manager, we will arrange for the transmittal of significant questions to the applicant. If you have any comments regarding areas being revieved by our contractor, LLNL, which you would like to make them aware of before receiving a draft review document, these comments should be sent to me and so noted.

Most importantly, regarding the site visit, each reviewer should provide, along with their questions, the objective of their site visit and the areas f they would like to see or the type of utility personnel with whom they would like to discuss specific questions by August 17, 1984. The DL Project Manager and I will then try to arrange a visit which will be the most beneficial to all parties concerned.

Please contact me (X27546) if you have any further questions.

r Sarah M. Davis i

Reliability and Risk Assessment Branch, DST l

Enclosure:

l Memorandum for Division Directors, /~C.I8 - N~#l -

dated June 21, 1984 Distribution RRAB Rdg Bl15'.

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P. Sobel, GSB, P-514 ,

N. Chokshi, SGEB, P-214 R. Pichumani, SGEB, P-214 A. Masciantonio, EQB, P-234 C. Ferrell, SAB, 242 J. Stang, CHEB, P-302 R. Jachowski, EHEB, P-314 J. Fairobent, METB, P-730 R. Anand, ASB, P-1022 J. Schiffgens, MTEB, P-328 W. Lyon, RSB, P-1132 K. Campe, SAB, 242 6 3 a . ~ . ~~

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ENCLOSURE AUG 161984

't JUN.211934 MEMORANDUM FOR: D. Eisenhut, Director, DL .

R. Vollmer, Director, DE R. Mattson, Director, DSI

. , , H. Thompson, Director, DHFS FROM: Themis P. Speis, Director Division of Safety Technology

SUBJECT:

REVIEW OF THE SEABROOK STATION PROBABILISTIC SAFETY ASSESSMENT A Probabilistic Safety Assessment (PSA) for the Seabrook Station Nuclear Power Plant was voluntarily performed and submitted to NRC by Public Service Company of New Hampshire, an OL applicant. The Reliability and Risk Assessment Branch (RRAB), Division of Safety Technolo_gy, has the responsibility for the overall coordination of the review ef, fort With the support of ,

Lawrence Livermore National Laboratory contracted to review the front-end (accident initiation through plant damage state) pgrtion of the PSA. _ ----

In view of the circumstances under which this PSA was submitted and the -

current status of the licensing of the Seabrook Station, the purpose.,and focus of this review will vary in some ways from ongoing and previous reviews of probabilistic safety assessments. To elaborate, due to the voluntary nature of the decision to perform and submit a PSA for Seabrook, a strictly narrow focus of verifying the accuracy of the numbers presented by extensive requantification or phenomenological analyses would not be an appropriate use of review resources. . .

Primary. foci, as in other reviews, would. remain ,to be the identification of significant vulnerabilities or weaknesses in design and proposed operation that may not have been considered in deterministic analyses, the identification

.of significant safety issues that may have generic implications, and the identification of any major problems that would be expected to significantly affect the results of the analysis and the safety of the plant. These conclusions will then be dealt with in accordance with NRR Office Letters l No. 40, No. 39, and No. 16, Revision 1.

In addition, the Seabrook PSA represents one of the latest PSAs which has incorporated lessons learned from past studies and advancements in the state-of-the-art of probabilistic safety analyses. An emphasis of the review should be to glean any new information that may be useful or affect the reviews of specific safety issues or other programs, i

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AUG 161984 The possibility of the pSA being used in the Phase 11 hearings for the Seabrook Station should be kept in mind. The hearings are expected to take place in late CY 1984/early 1985. The issue of emergency planning is . _ ,

expected to be a prominent part of these hearings which is a likely area where there may be use of risk assessment results.

The schedule for this review calls for prelimincry findings being submitted to RRAB by October 15, 1984. Enclosed with this memo is a delineation of portions of the PSA to be reviewed by the designated divisions (s) with guidance as to the type of review being requested. We nould like to have any questions on significant areas for transmittal to LLNL for consideration in their' review, or if needed, to be discussed with the applicant, by August 1,1984 so that resolution and incorporation in the preliminary report from LLNL will take place as early as possible in order to expedite the finalization of the review document. In consideration of the circumstances and nature of this review, we are planning on only one site visit. The date of this visit must be coordinated with all necessary participants, (i.e., contractors, subcontractors and reviewers).so as to minimize the burden of time and resources expended on this review by the utility. We would also like to emphasize that there be close coordination between the front-End and back-end reviewers in DST and DSI and respective contractors so that the ~

final review will be a cohesive, integrated assess. ment of the Seabrook Stadoa.

The Division of Engineering will support RRAB in overseeing the review effort -

by LLNL on external events. . , _-

The final product of the review will be in the form of a NUREG/CR. "Trrere remains the possibility of SERs or testimony being required in s'upport of the licensing of Seabrook.

SarahM. Davis,ofRRABisthecoordinatorfortheSeab.rookPSkReview.

Ms. Davis can- be contacted on X27546.

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i ORIGIt;AL SIG!:ED BY Themis P. Speis, Director Division of Safety Technology l

Enclosure:

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AUG 161984 Proposed Schedule LLNL - Review through plant damage state __

Identification of major errors or inconsistencies. Estimation of impact on dominant accident sequences and revised estimates where,.

appropriate. Summary of results, review conclusions, and major insights gained.

10/15/84 Oraft Report '

Internal NRC Review OST - Review to core damage state, Generic Safety Issues (medium and high priority), potential new GSis, and over,all coordination.

DSI - Critique of the containment failure analysis. identifying strengths and weaknesses of containment design and critique of release category assignment. Provide major insights in this area and any significant variations in the conditional failure -

probabilities and release fractions.- A, brief review of .,--

consequence analysis should als'o be perTormed. Based on-the -

~7esults of the consequencs rev.iew, containeent failure conditional ____

probabilities, and release fractions, limited con' sequence analysis

. may be needed.

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10/15/84 Draf t Report (Critique and Conclusions)

DE - Support in overseeing-the contractor review of external events.

Please provide a critique of the external events analyses (e.g.,

seismic," fire, etc.) contained in the Seabrook PRA with the -

8 appropriate 'upport s from other Branches / Divisions (e.g., ASB, METB, etc.). Any questions or comments to be transmitted to the contractor should be formulated and submitted to RRAB by August 1, 1954 10/15/84 Draft Report (Critique and Conclusions)

Other - Upon receipt of the contractor report (10/15/84), we will request Support review support and limited calculations where appropriate from other Divisions and Branches in areas of their expertise, especially for those areas where reestimates were made which affect the set of dominant sequences and overall results of the PRA. Designation of specific sections to be reviewed will be l transmitted to each Branch / Division at that time.

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t BNL NEEDS DURING SEABROOK PLANT TOUR

1. Vessel cavity and annulus surrounding vessel, including all con-necting volumes and associated structure. The interest is flow paths for gaseous or suspended material leaving the vessel, in-cluding core melt material that is swept along by high steam and gaseous flow, during accident conditions via breach of any portion of the vessel or connections to the vessel and observation of anything that intercepts or otherwise interacts with the flow. Of

- particular interest are the path leading to the seal table and beyond, from the vessel cavity up the side of the vessel into the upper containment, and any flow paths around ,the steam generators

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from the lower portion of containment to the upper containment.

2. Water or core melt collection locations and flow paths for liquid.

The interest is any low points or volumes in containment where liquid can collect prior to flowing to the sump and the vessel cayity, including the flow paths.

3. The entire ECC system. This includes all piping, valves, heat exchangers, pumps, interconnections with other systems, controls, and associated building structure, including building isolation, venting, ventilation, and cooling provisions. potential flow paths for movement of material from the ECC system to the surroundings such as would occur in the "V" sequence (uncontrolled LOCA oltside of co'ntainment) are of interest.
4. Flow paths other than the ECC system which may provide a conduit for release of material from the RCS pressure boundary to the surroudings involving bypass of containment. This includes the steam lines, steam generator feed lines, steam generator code valves, and various let-down lines.
5. The containment system in general. This includes the overall containment, as well as detail pertinent to containment penetra-tions (electrical lead-throughs, piping, purge and vent lines and i valves), atmosphere control within containment (coolers and sprays, including the systems that support these), and the annular space between the containment walls, including the systems used for control and ventilation of the annular space.
6. Containment basemat information, including type of concrete (compo-sition if readily available), construction detail, including sump configuration, thickness, reinforcement, and interconnections of sump with other equipment.

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