ML20141K293

Forwards Draft Repts Re Technical Insights Gained from Pras. Repts Contain Discussions of General Insights on Plant Strengths & Weaknesses & Contributions to Core Melt Frequency from Sequences Induced by Events.W/O Encl

ML20141K293
Person / Time
Site:	Calvert Cliffs
Issue date:	01/09/1986
From:	Thadani A Office of Nuclear Reactor Regulation
To:	Tiernan J BALTIMORE GAS & ELECTRIC CO.
References
NUDOCS 8601220433
Download: ML20141K293 (2)

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- January 9,1986 Docket Nos. 50-317 NRC & Local PDR ACRS (10) FMiraglia i and 50-318 STL File JPartlow PKreutzer l BGrimes DJaffe AThadani PWR8 Reading EJordan DocketiFiles Mr. J. A. Tiernan spwame O Vice President - Nuclear Energy Baltimore Gas & Electric Company P. O. Box 1475 Baltimore, Maryland 21203

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 probabilistic risk assessments 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; i and the contribution to measures of risk (core melt frequency and consequences i

of radioactive releases) from systems, components and events.

These reports will be published in their final forms in approximately two months.

These reports are being provided to you, as well as all other licensees, in advance of formal publication for your information. If, after reviewing these reports, you wish to provide comments to the staff, please provide them by February 10, 1986.

Sincerely,

/S/

B601220433 860109 Ashok Thadani, Director PDR ADOCK 05000317 PWR Project Directorate #8 P PDR Division of PWR Licensing - B

Enclosures:

As Stated cc w/o.enclosur,e5 See~next pagd " /

PBD#8 P8Df8

.ebtzer Pfg/q/86 PB DJ e [f AThadani I l / /86 // /86 u -. - .. . . _ . . . . . _. _. ___ _. __

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I Mr. J. A. Tiernan Baltimore Gas & Electric Company Calvert Cliffs Nuclear Power Plant cc:

Mr. William T. Bowen, President Regional Administrator, Region I Calvert County Board of U.S. Nuclear Regulatory Commission

! Commissioners Office of Executive Director l Prince Frederick, Maryland 20768 for Operations 631 Park Avenue

! D. A. Brune, Esq. King of Prussia, Pennysivania 19406 i General Counsel i Baltimore Gas and Electric Company P. O. Box 1475 Baltimore, Maryland 21203 I George F. Trowbridge, Esq.

Shaw, Pittman, Potts and Trowbridge

1800 M Street, NW Mr. W. J. Lippold, Manager i

Washington, DC 20036 Nuclear Engineering Services Calvert Cliffs Nuclear Power Plant i Mr. J. R. Lemons MD Rts 2 & 4, P. O. Box 1535 Manager Nuclear Operations Lusby, Maryland 20657-0073 Baltimore Gas and Electric Company i Calvert Cliffs Mr. M. E. Bowman, General Supervisor Technical Services Engineering MD Rts 2 & 4 Post Office Box 1535 Calvert Cliffs Nuclear Power Plant Lusby, Maryland 20657-0073 MD Rts 2 & 4, P. O. Box 1535 Lusby, Maryland 20657-0073

, Resident Inspector c/o U.S. Nuclear Regulatory Commission Combustion Engineering, Inc.

i P. O. Box 437 ATTN: Mr. R. R. Mills, Manager Lusby, Maryland 20657-0073 Engineering Services

P. O. Box 500 I

Mr. Leon B. Russell Windsor, Connecticut 06095 i

Manager - Nuclear Maintenance Calvert Cliffs Nuclear Power Plant Department of Natural Resources MD Rts 2 and 4, P. O. Box 1535 Energy Administration, Power Plant Lusby, Maryland 20657-0073 Siting Program ATTN: Mr. T. Magette

, Bechtel Power Corporation Tawes State Office Building ATTN: Mr. D. E. Stewart Annapolis, Maryland 21204 Calvert Cliffs Project Engineer 15740 Shady Grove Road Gaithersburg, Maryland 20760

Mr. R. M. Douglass, Manager Quality Assurance & Support Services l Baltimore Gas and Electric Company l Calvert Cliffs Nuclear Power Plant P. O. Box 1535 Lusby, Maryland 20657-0073 i

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