ML20154J580

Forwards Draft Repts Re Technical Insights Gained from Pra. Repts Include Info on Plant Strengths & Weaknesses,Core Melt Frequency,Measures of Risk & Procedural/Hardware Mods in Response to PRA Problems

ML20154J580
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	03/03/1986
From:	Varga S Office of Nuclear Reactor Regulation
To:	Farrar D COMMONWEALTH EDISON CO.
References
NUDOCS 8603100671
Download: ML20154J580 (2)

Text

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March 3, 1986 Docket Nos. 50-295 DISTRISBUTION w/o encl.

and 50-304 EcketFile NRC PDR PAD-3 Rdg H. Thompson L PDR Gray File Mr. D. L. Farrar OELD J. Norris Director of Nuclear Licensing C. Vogan E. Jordan Commonwealth Edison Company B. Grimes J. Partlow Post Office Box 767 ACRS 10 Chicago, Illinois 60690

SUBJECT:

REPORTS ON PRA INSIGHTS Enclosed are two draft reports concerning technical insights gained from Probabilistic Risk Assessments (PRAs). These reports are the outcome of an ongoing effort to make available and utilize in numerous technical and managerial activities the information in PRAs regarding the factors which dominate the risk associated with nuclear power plants. This effort includes identification of the features of design or operational practices which have been found to be important to safety in the types of plants which have been subjected to risk assessments. In addition, the section on insights into PRA methodologies focuses on areas which are sensitive to the results and the overall perception of plant weaknesses and vulnerabilities.

In particular, these reports contain discussions of: general insights on plant strengths and weaknesses gained from PRAs; the contribution to core melt frequency from classes of sequences induced by various initiating events; modifications, both hardware and procedural, which have been implemented to address problems identified in the conduct or as a result of PRAs; insights into PRA methodologies; and the contribution to measures of risk (core melt frequency and consequences of radioactive releases) from systems, components and events.

These reports are being provided to you, as well as all other licensees, in advance of formal publication for your information. Your connents and suggestions are welcome on these reports.

Sincerely,

/s/JNorris for Steven A. Varga, Director PWR Project Directorate #3 Division of PWR Licensing-A

Enclosures:

As stated cc:

See next page

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9 Mr. D. L. Farrar Comonwealth Edison Company Zion Station cc:

Rabert J. Vollen, Esquire Mr. Michael C. Parker, Chief 109 North Dearborn Street Division of Engineering Chicago, Illinois 60602 Illinois Department of Nuclear Safety Dr. Cecil Lue-Hing 1035 Outer Park Drive, 5th Floor Director of Research and Development Springfield, Illinois 62704 Metropolitan Sanitary District of Greater Chicago 100 East Erie Street Chicago, Illinois 60611 Mr. Phillip P. Steptoe Isham, Lincoln and Beale i Counselors at Law T Three First National Plaza

{ Sist Floor Chicago, Illinois 60602

[

Susan N. Sekuler Esquire lr Assistant Attorney General Environmental Control Division 188 West Randolph Street, Suite 2315 Chicago, Illinois 60601 ,

Mayor of Zion Zion, Illinois 60099 F Illinois Department of Nuclear Safety r ATTN: Manager, Nuclear Facility Safety 1035 Outer Park Drive, 5th Floor l Springfield, Illinois 62704 U.S. Nuclear Regulatory Commission Resident Inspectors Office 105 Shiloh Blvd.

Zion, Illinois 60099 Regional Administrator, Region III U.S. Nuclear Regulatory Comission 799 Roosevelt Road Glen Ellyn, Illinois 60137

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