ML17059C283
| ML17059C283 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 10/15/1998 |
| From: | Hood D NRC (Affiliation Not Assigned) |
| To: | Mueller J NIAGARA MOHAWK POWER CORP. |
| Shared Package | |
| ML17059C285 | List: |
| References | |
| TAC-MA2286, NUDOCS 9810200030 | |
| Download: ML17059C283 (8) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20mr4001 October 15, 1998 Mr. John H. Mueller Chief Nuclear Officer Niagara Mohawk Power Corporation Nine Mile Point Nuclear Station Operations Building, Second Floor Lycoming, NY 13093
SUBJECT:
CORE SHROUD INSPECTION AND FLAW EVALUATIONFOR OPERATION AFTER REFUELING OUTAGE 6, NINE MILEPOINT NUCLEAR STATION, UNIT NO. 2 (TAC NO. MA2286)
Dear Mr. Mueller:
By letter dated July 9, 1998, as supplemented September 21, 1998, Niagara Mohawk Power Corporation (NMPC) submitted results of the ultrasonic inspection of core shroud welds during the 1998 refueling outage (RFO6) at Nine Mile Point Nuclear Station, Unit 2 (NMP2), and provided a fiaw evaluation for the continued operation of NMP2 for one operating cycle.
Following the detection of significant cracking (i.e., in excess of 10 percent of the inspected length) in horizontal weld H4, NMPC inspected accessible areas of all horizontal welds in accordance with the Boiling Water Reactor Vessel and Internals Project's (BWRVIP's) "BWR Core Shroud Inspection and Flaw Evaluation Guidelines" (BWRVIP-01), Revision 2. These additional inspections revealed significant cracking in welds H5 and H7; minor cracking in welds H1, H2, H3, and H8; and no cracking in weld H6. NMPC also inspected accessible areas of vertical welds V12, V13, V14, V15, V16, and V17 and found no evidence of cracking.
NMPC's letter of July 9, 1998, included a report by General Electric Nuclear Energy, GENE-B13-01920-63, Revision 2, "The Evaluation Of Nine Mile Point Unit 2 Shroud Cracking For At Least One Fuel Cycle Of Operation Following RFO6," dated June 1998, which describes the observed cracking in the horizontal shroud welds and presents the results of a structural margin evaluation.
The NRC staff has completed its review of your submittals.
In the enclosed safety evaluation, the NRC staff concludes that the flaw evaluation meets the rules of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, "Rules for In-Service Inspection of Nuclear Power Plant Components."
Since the predicted final flaw depth at the end of the operating cycle has a calculated safety factor that exceeds the safety factor required by the ASME Code, the NRC staff concludes that continued operation, without repair or intermediate inspection of the NMP2 core shroud, is acceptable for at least the operating cycle that follows RFO6.
The NRC staff acknowledges that you believe the current analysis, which is based upon the bounding crack growth rate of 5 x 10~ inch/hour specified in BWRVIP-01, is conservative and that you plan to submit a revised analysis in the future that may justify operations for two cycles.
The revised analysis willbe based upon the NRC staffs recent approval of BWRVIP-14, "Evaluation of Crack Growth in BWR Stainless Steel Reactor Pressure Vessel Internals." The NRC staff also acknowledges that NMPC willsubmit its NMP2 core shroud reinspection plan to the NRC staff at least 8 months before the RFO7 reinspection is performed, and willprovide the results of the RFO7 reinspection to the NRC staff within 30 days of its completion.
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J. Mueller This completes our review under TAG No. MA2286. Ifyou have questions regarding this letter or the enclosure, contact me by phone at (301) 415-3049 or by electronic mail at dsh@nrc.gov.
Sincerely, Darl S. Hood, Senior Project Manager Project Directorate l-1 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Docket No. 50-410
Enclosure:
Safety Evaluation ccw/encl: See next page
9: Mueller October 1,S, 1998 This completes our review under TAC No. MA2286. Ifyou have questions regarding this letter or the enclosure, contact me by phone at (301) 492-3049 or by electronic mail at dshonrc.gov.
Sincerely, Original signed by:
Darl S. Hood, Senior Project Manager Project Directorate I-1 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Docket No. 50-410
Enclosure:
Safety Evaluation ccw/encl: See next page Distribution:
/Dockage'[eQ PUBLIC PDI-1 R/F OGC ACRS CCowgill, Rl DHood SBajwa MBanic KWichman CCarpenter JStrosnider RHermann CSheng DOCUMENT NAME: G:>NMP2>NM2A2286.LTR To receive a copy of this document, indicate in the born "C" ~ Copy without enclosures "E" ~ Copy with enclosures "N" ~ No copy OfFICE PM:PDI-1 LA:PDI-1 D:PDI-1'ANE DATE DHood/rsl >s'/9 SL1ttl 10/ V/98 10/I
/98 SBajwa 10/ 5/98 OFFICIALRECORD COPY
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John H. Mueller Niagara Mohawk Power Corporation CC:
Regional Administrator, Region I
U. S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 Resident Inspector Nine Mile Point Nuclear Station P.O. Box 126 Lycoming, NY 13093 Mr. Jim Rettberg NY State Electric 8 Gas Corporation Corporate Drive Kirkwood Industrial Park P.O. Box 5224 Binghamton, NY 13902-5224 Mr. John V. Vinquist, MATS Inc.
P.O. Box 63 Lycoming, NY 13093 Supervisor Town of Scriba Route 8, Box 382 Oswego, NY 13126 Mr. Richard Goldsmith Syracuse University College of Law E.l. White Hall Campus
- Syracuse, NY 12223 Nine Mile Point Nuclear Station Unit No. 2 Charles Donaldson, Esquire Assistant Attorney General New York Department of Law 120 Broadway New York, NY 10271 Mr. Timothy S. Carey Chair and Executive Director State Consumer Protection Board 5 Empire State Plaza, Suite 2101 Albany, NY 12223 Mark J. Wetterhahn, Esquire Winston 8 Strawn 1400 L Street, NW.
Washington, DC 20005-3502 Gary D. Wilson, Esquire Niagara Mohawk Power Corporation 300 Erie Boulevard West
- Syracuse, NY 13202 Mr. F. WilliamValentino, President New York State Energy, Research, and Development Authority Corporate Plaza West 286 Washington Avenue Extension Albany, NY 12203-6399
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