ML20247K591

Advises That Plant PRA Considered Fair Evaluation of Most Likely Paths to Core Damage at Plant.W/Stated Exceptions, Review of PRA Did Not Uncover Any Reason Why PRA Could Not Be Used as Aid to Evaluate Plant Mods or for Decisions

ML20247K591
Person / Time
Site:	Crystal River
Issue date:	09/18/1989
From:	Silver H Office of Nuclear Reactor Regulation
To:	Wilgus W FLORIDA POWER CORP.
References
RTR-NUREG-CR-5246 TAC-66713, NUDOCS 8909210208
Download: ML20247K591 (3)

Text

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WASHINGTON, D. C. 20555 g September 18, 1989 Docket No. 50-302 Mr. W. S. Wilgus Vice President, Nuclear Operations Florida Power Corporation ATTN

Manager, Nuclear Operations Licensing P. O. Box 219-NA-21 Crystal River, Florida 32629

SUBJECT:

CRYSTAL RIVER UNIT 3 - PROBABILISTIC RISK ASSESSMENT (PRA) FOR CRYSTAL RIVER UNIT 3 (CR-3) (TAC NO. 66713)

Florica Power Ccr puration (FPC) letter of November 2,1987 provided a copy of the CR-3 PRA. We undertook a limited-scope review of the PRA through the Office of Research, who contracted with Argonne National Laboratory (ANL) to perform the review. That review has been completed and the results documented in NUREG/CR-5245 which was published in January 1989.

The ANL review concluded that the PRA was generally state-of-the-art and well performed. The review cnncluced that within the scope of the PRA's review, the PRA identifica the major failures that contribute the most to estimated core damage frequency.

It is noted that the CR-3 PRA did not include an analysis of:

- the Non-Nuclear Instrumentation System (NN1)

- the Heating, Ventilation, and Air-Conditioning System (HVAC)

- the Integrated Control System (ICS).

In addition, the PRA did not document the results of its investigt. tion of ATWS events, and omitted modeling a significant number of common cause failures and failure combinations involving maintenance unavailabilities of some critica.1 system components. Details of these limitations are discussed in NUREG/CR-5245.

These omissions and limitations should be recognized in using the PRA to evaluate plant modifications and in helping in regulatory or licensing decisions.

It is also recognized that many plant modification are in process or have recently been made which would have an effect on the PRA and on ANL's review.

For example, the review assigned a higher value to the small LOCA-indaced core damage frequency based on not stopping the low pressure injection pumps when they are subject to damage because of low-flow operation. However, logic changes to be made during the next refueling outage (spring 1990) will minimize this concern.

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Mr. W.S. Wilgus September 18, 1989 In conclusion, we find the Crystal River-3 PRA to be a fair evaluation of the most likely paths to core damage at the plant. With the exceptions mentioned above, our review of the PRA has not uncovered any reasons why the PRA could not be used as an aid to evaluate plant modifications and as an input in making regulatory or licensing decisions.

This concludes our efforts on TAC No. 66713.

Sincerely, Original signed by Harley Silver, Project Manager Project Directorate 11-2 Division of Reactor Projects - 1/11 Office of Nuclear Reactor Regulation cc:

See next page DISTRIBUTION Docket File NRC & LPDRs PD22 Rdg File SVarga 14/E/4 Glainas 14/H/3 HBerkow HSilver GWunder DMiller OGC (for info only)

EJordan MNBB-3302 DGrimes ACRS(10)

Document Name: PRA CR3 TAC 66713

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Mr. W. S. Wilgus Crystal River Unit No. 3 Nuclear Florida Power Corporation Generating Plant l- CC:

Mr. A. H. Stephens State Planning and Development Gene'ral Counsel Clearinghouse Florida Power Corporation Office of Planning and Budget MAC - ASD -

. Executive Office of the Governor P. O. Box 14042 The Capitol Building St. Petersburg, Florida 33733 Tallahassee, Florida 32301 Mr. P. F. McKee, Director Chairman Nuclear Plant Operations Board of County Commissioners Florida Power Corporation Citrus County

,.. P. O. Box 219-NA-2C 110 hot th Apopka' Avenue Crystal River, Florida 32629 Inverness Florida 32650 Mr. Robert B. Borsum Mr. Rolf C. Widell, Director Babcock & Wilcox Nuclear Operations Site Support Nuclear Power Generation Division Florida Power Corporation 1700 Rockville Pike, Suite 525 P.O. Box 219-NA-21 Rockville, Maryland 20852 Crystal River, Florida 32629 Senior Resident Inspector Mr. Gary L. Boldt

' Crystal River Unit 3 Vice President, Nuclear Production U.S. Nuclear Regulatory Comission '

Florida Power Corporation 15760 West Powerline Street P. O. Box 219-SA-2C Crystal River, Florida 32629 Crystal River, Florida 32629 Regional Administrator, Region II U.S. Nuclear Regulatory Commission 101 Marietta Street N.W., Suite 2900 Atlanta, Georgia 30323 Mr. Jacob Daniel Nash Office of Radiation Control Department of Health and Rehabilitative Services 1317 Winewood Blvd.

Tallahassee, Florida 32399-0700 Administrator Department of Environmental Regulation Power Plant Siting Section State of Florida 2600 Blair Stone Road Tallahassee, Florida 32301 Attorney General Department of Legal Affairs The Capitol Tallahassee, Florida 32304 1

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