ML17056C175
| ML17056C175 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 12/17/1992 |
| From: | Terry C NIAGARA MOHAWK POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML17056C176 | List: |
| References | |
| GL-92-01, GL-92-1, NMP1L-0723, NMP1L-723, TAC-M83486, NUDOCS 9212220263 | |
| Download: ML17056C175 (6) | |
Text
ACCEI.ERAT DOCUMENT DIST UTION SYSTEM REGULAT INFORMATION DISTRIBUTION STEM (RIDS)
ACCESSION NBR:9212220263 DOC.DATE: 92/12/17 NOTARIZED: NO DOCKET FACIL:50-220 Nine Mile Point Nuclear Station, Unit 1, Niagara Powe 05000220 AUTH.NAME AUTHOR AFFILIATION TERRYiC.D.
Niagara Mohawk Power Corp.
RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
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SUBJECT:
Responds to NRC 920812 ltr containing recommendation that I
util perform analysis to demonstrate that two beltline plates have margins of safety against fracture equivalent, per App G of ASME Code,per GL 92-01.Final rept encl.
DISTRIBUTION CODE:
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S TITLE: Generic Letter 92-01 Responses (Reactor Vessel Structural Integrity 1
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PLEASE HELP US TO REDUCE WASTEI CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 504-2065) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!
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NIAGARAMOHAWKPOWER CORPORATION/301 PLAINFIELDROAD, SYRACUSE, N.Y. 13212/TELEPHONE (315) 474-1511 December 17, 1992 NMP1L 0723 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 Re:
Nine Mile Point Unit 1 Docket No. 50-220 DPR-63 TA No. M8 486
SUBJECT:
GENERIC LETTER 92-01, REVISION 1, REACTOR VESSEL STRUCTURAL INTEGRITY, 10CFR50.54(f), ELASTIC-PLASTIC FRACTURE MECHANICS ASSESSMENT Gentlemen:
By letter dated August 12, 1992, the Staff recommended that Niagara Mohawk perform an analysis to demonstrate that two beltline plates with Charpy upper shelf energies (USE) less than 50 ft-lb have margins of safety against fracture equivalent to those required by Appendix G of the ASME Code.
The Staff also recommended that a lower 95 percent confidence value for J, (deformation J-integral) be used to represent conservative material properties for Levels A, B, and C Service Loadings and a mean value for J, be used to represent the best estimate properties for Level D Service Loadings.
Our letter of October 16, 1992 (NMP1L 0707) responded to the Staff's request and provided a report entitled, "Elastic-Plastic Fracture Mechanics Assessment of Nine Mile Point Unit 1 Beltline Plates for Service Level A and B Loadings."
In a subsequent letter of November 13, 1992, the Staff stated that after further evaluation they should have recommended that in determining the conservative material properties for Levels A, B, and C Service Loadings, the mean value for J, should be reduced by two standard deviations.
This change in calculational methodology has required Niagara Mohawk to reassess the two beltline plates for Service Level A and B loadings.
Enclosed is a copy of our revised report, "Elastic-Plastic Fracture Mechanics Assessment of Nine Mile Point Unit 1 Beltline Plates for Service Level A and B Loadings."
This report incorporates the Staff's recommendation that the mean value of J, be reduced by two standard deviations.
Although more conservative J,-Resistance Curves were used in the revised analysis, the minimum USE levels remain unchanged for both the A533B and A302B material models.
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Our letter of October 16, 1992 indicated that separate reports addressing Service Level C and D loading calculations and USE estimates for the beltline welds would be submitted by January 29, 1993.
In accordance with the Staff's recommendation, we willuse the mean value of J, reduced by two standard deviations for the Service Level C loading analysis and the mean value of J, for the Service Level D loading analysis.
Due to the recalculation of Service Level A and B loadings contained herein, these reports willnow be submitted by March 1, 1993.
The Staff has agreed that this date is acceptable.
Very truly yours, C. D. Terry Vice President Nuclear Engineering AER/mls 003442GG Enclosure xc:
Regional Administrator, Region 1
Mr. R. A. Capra, Director, Project Directorate I-l, NRR Mr. D. S. Brinkman, Senior Project Manager, NRR Mr. W. L, Schmidt, Senior Resident Inspector Mr. K. Cozens, NUMARC Records Management
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