ML102730456
| ML102730456 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 10/08/2010 |
| From: | David M Plant Licensing Branch III |
| To: | Pacilio M Exelon Nuclear |
| David Marshall NRR/DORL/LPL3-2 415-154 | |
| References | |
| TAC ME3510, TAC ME3511, TAC ME3512, TAC ME3513 | |
| Download: ML102730456 (4) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 October 8, 2010 Mr. Michael J. Pacilio President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville,IL 60555
SUBJECT:
BRAIDWOOD STATION, UNITS 1 AND 2, AND BYRON STATION, UNIT NOS. 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION RELATED TO REQUEST FOR RELIEF FROM ASME CODE CASE N-729-1 REQUIREMENTS FOR EXAMINATION OF REACTOR VESSEL HEAD PENETRATION WELDS (TAC NOS. ME3510, ME3511, ME3512, AND ME3513)
Dear Mr. Pacilio:
By letter to the Nuclear Regulatory Commission (NRC) dated March 12, 2010 (Agencywide Documents Access and Management System Accession No. ML100710764), Exelon Generation Company, LLC (the licensee) submitted a relief request (RR) for the third 10-year inservice inspection interval at Braidwood Station, Units 1 and 2, and Byron Station, Unit Nos. 1 and 2. The RR proposed an alternative to the requirements in Title 10 of the Code of Federal Regulations, paragraph 50.55a(g)(6)(ii)(D) for the inservice inspection of the reactor pressure vessel upper heads in accordance with American Society of Mechanical Engineers Boiler and Pressure Vessel Code Case N-729-1, "Alternative Examination Requirements for PWR Reactor Vessel Upper Heads With Nozzles Having Pressure-Retaining Partial-Penetration Welds," with NRC conditions.
The NRC staff is reviewing your submittal and has determined that additional information is required to complete its review. The specific information requested is addressed in the enclosed Request for Additional Information (RAJ). Your staff has agreed to provide a response to the RAI within 60 days after the date of this letter.
M. Pacifio
- 2 The NRC staff considers that timely responses to RAls help ensure sufficient time is available for NRC staff review and contribute toward the NRC's goal of efficient and effective use of its staff resources. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-1547.
Sincerely, u~g- ))(~-
Marshall J. David, Senior Project Manager Plant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. STN-456, STN-457, STN 50-454, and STN 50-455
Enclosure:
Request for Additional Information cc w/encl: Distribution via ListServ
REQUEST FOR ADDITIONAL INFORMATION BRAIDWOOD STATION. UNITS 1 AND 2 AND BYRON STATION. UNIT NOS. 1 AND 2 DOCKET NOS. STN 50-456. STN 50-457.
STN 50-454. AND STN 50-455 By letter to the Nuclear Regulatory Commission (NRC) dated March 12, 2010 (Agencywide Documents Access and Management System Accession No. ML100710764), Exelon Generation Company, LLC (the licensee) submitted a relief request for the third 10-year inservice inspection interval at Braidwood Station, Units 1 and 2, and Byron Station, Unit Nos. 1 and 2. The relief request proposed an alternative to the requirements in Title 10 of the Code of Federal Regulations (10 CFR), paragraph 50.55a(g)(6)(ii)(D) for the inservice inspection of the reactor pressure vessel upper heads in accordance with American Society of Mechanical Engineers Boiler and Pressure Vessel Code Case N-729-1, "Alternative Examination Requirements for PWR Reactor Vessel Upper Heads With Nozzles Having Pressure-Retaining Partial-Penetration Welds," with NRC staff conditions.
The NRC staff has reviewed and evaluated the information provided by the licensee and has determined that the following information is needed in order to complete its review of the relief request.
- 1. The NRC staff requests the licensee's basis for not performing a surface examination of the lower portion of each penetration nozzle necessary to meet the inspection requirements of 10 CFR 50.55a(gX6)(ii)(D). As currently written, the NRC staff finds insufficient basis to grant relief under 10 CFR 50.55a(aX3)(i), as surface examinations could be performed on each penetration nozzle to meet the current inspection requirements.
- 2. The NRC staff notes that the time period of the licensee's basis, in Figure 12 and Section 5.1 of the relief request, 6 effective full power years (EFPY), may not bound the possible period of time between inspections, 8 calendar years or 2.25 reinspection years, whichever is less.
In Figure 12, the licensee's flaw analysis for penetration nozzle number 68 on Byron Station, Unit No.1, shows that a flaw would take 6 EFPY to grow from the uninspected region of the nozzle to the toe of the J-groove weld. As well, in Section 5.1 of the relief request, the licensee states, in part, "Figures 7 through 12 below demonstrate that obtaining at least 0.55" below the J-groove weld is sufficient to allow for a minimum of six effective full power years (EFPY) or four 18-month cycles between examinations." The NRC staff notes that under Item No. B4.20 of Table 1 of ASME Code Case N-729-1, the Extent and Frequency of Examinations reads, in part, "All nozzles, every 8 calendar years or before RIY=2.25, whichever is less." Therefore, the NRC staff requests additional information or clarification to support this difference in time between required inspection frequency and the licensee's basis for continued operation with a reduced inspection area.
ENCLOSURE
M. Pacilio
- 2 The NRC staff considers that timely responses to RAls help ensure sufficient time is available for NRC staff review and contribute toward the NRC's goal of efficient and effective use of its staff resources. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-1547.
Sincerely, IRA by N. DiFrancesco for M. Davidl Marshall J. David, Senior Project Manager Plant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. STN 50-456 and STN 50-457
Enclosure:
Request for Additional Information cc w/encl: Distribution via ListServ DISTRIBUTION:
PUBLIC LPL3-2 RlF RidsNrrDorlLpl3-2 Resource RidsNrrPMBraidwood Resource RidsNrrPMByron Resource RidsNrrLATHarris Resource RidsAcrsAcnw_MailCTR Resource RidsRgn3MailCenter Resource RidsOgcRp Resource NRRRidsNrrDorlDpr Resource RidsNrrDciCpnb Resource JColiins, NRR ADAMS Accession Number* ML102730456
- Date of RAI Memo NRR-088 OFFICE LPL3-2/PM LPL3-2/LA DCI/CPNB/BC LPL3-2/BC LPL3-2/PM NAME MDavid THarris TLupold*
RCarison NDiFrancesco for MDavid DATE 10/5/10 10/1/10 9/23/10 10/7/10 10/8/10 OFFICIAL RECORD COPY