ML17058B043

Discusses Rev to Staff Recommendations for Performing elastic-plastic Fracture Mechanics Analysis,Per Response to GL 92-01,rev 1 Re Reactor Vessel Structural Integrity

ML17058B043
Person / Time
Site:	Nine Mile Point
Issue date:	11/13/1992
From:	Brinkman D Office of Nuclear Reactor Regulation
To:	Sylvia B NIAGARA MOHAWK POWER CORP.
References
GL-92-01, GL-92-1, TAC-M83486, NUDOCS 9211190012
Download: ML17058B043 (8)

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Docket No. 50-220 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON. D.C. 20555 November 13, 1992 Mr. B. Ralph Sylvia Executive Vice President, Nuclear Niagara Mohawk Power Corporation 301 Plainfield Road

Syracuse, New York 13212

SUBJECT:

REVISION TO NRC STAFF RECOMMENDATIONS FOR PERFORMING ELASTIC-PLASTIC FRACTURE MECHANICS ANALYSIS FOR NINE MILE POINT NUCLEAR STATION UNIT NO.

1 REACTOR VESSEL (TAC NO. M83486)

By letter dated August 12,

1992, the NRC staff provided a preliminary response to Niagara Mohawk Power Corporation's (NMPC) response to NRC Generic Letter 92-01, Revision 1,

"Reactor Vessel Structural Integrity, 10 CFR 50.54(f)," for Nine Mile Point Unit No.

1 (NMP-1).

In the second paragraph of our August 12, 1992, letter, we recommended that NMPC perform an elastic-plastic fracture mechanics analysis to demonstrate that plates in the NMP-1 reactor vessel with Charpy upper shelf energies of less than 50 ft lb have margins of safety against fracture equivalent to those required by Appendix G of the ASME Code.

We further recommended that a lower 95 percent confidence value for J be used to represent conservative material properties for Levels A, B, and C $ervice Loadi'ngs and a mean value for J be used to represent the best estimate properties for Level D Service toadings.

Upon further evaluation we have

, determined that we should have recommended that in determining the conservative material properties for Levels A, B, and C Service

Loadings, the mean value for Jd should be reduced by two standard deviations.

We apologize for any inconvenience caused by our change in recommended calculational method.

Preliminary discussions with Mr. Nick Spagnoletti of your staff indicate this change in calculational methodology will delay 9211190012 921113 PDR ADOCK 05000220 P

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Mr. B. Ralph Sylvia November 13, 1992 submittal of the recommended analysis by approximately 30 days.

Although we urge NMPC to complete this analysis as soon as possible, we agree that a delay of up to 30 days may be unavoidable and is acceptable.

Please contact me at (301) 504-1409 if you have any questions regarding this issue.

Sincerely, cc:

See next page Donald S.

Brinkman, Senior Project Manager Project Directorate I-l Division of Reactor Projects I/II Office of Nuclear Reactor Regulation

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Hr. B. Ralph Sylvia Niagara Mohawk Power Corporation Nine Mile Point Nuclear Station Unit No.

1 CC:

Hark J. Wetterhahn, Esquire Winston

& Strawn 1400 L Street, NW Washington, DC 20005-3502 Supervisor Town of Scriba Route 8, Box 382

Oswego, New York 13126 Resident Inspector U.S. Nuclear Regulatory Commission Post Office Box 126

Lycoming, New York 13093 Gary D. Wilson, Esquire Niagara Mohawk Power Corporation 300 Erie Boulevard West

Syracuse, New York 13202 Regional Administrator, Region I

U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, Pennsylvania 19406 I

Ms.

Donna Ross New York State Energy Office 2 Empire State Plaza 16th Floor

Albany, New York 12223 Hr. Kim Dahlberg Unit 1 Station Superintendent Nine Mile Point Nuclear Station Post Office Box 32

Lycoming, New York 13093 Hr. David K. Greene Manager Licensing Niagara Hohawk Power Corporation 301 Plainfield Road

Syracuse, New York 13212 Charles Donaldson, Esquire Assistant Attorney General New York Department of Law 120 Broadway New York, New York 10271 Hr. Paul D.

Eddy State of New York Department of Public Service Power Division, System Operations

'3 Empire State Plaza

Albany, New York 12223

Hr. B. Ralph Sylvia November 13, 1992 submittal of the recommended analysis by approximately 30 days.

Although we urge NHPC to complete this analysis as soon as possible, we agree that a delay of up to 30 days may be unavoidable and is acceptable.

Please contact me at (301) 504-1409 if you have any questions regarding this issue.

Sincerely, Original signed by:

cc:

See next page Donald S.

Brinkman, Senior Project Manager Project Directorate I-l Division of Reactor Projects I/II Office of Nuclear Reactor Regulation Distribution:

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