ML091260242
| ML091260242 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 05/11/2009 |
| From: | David M Plant Licensing Branch III |
| To: | Pardee C Exelon Nuclear |
| david marshall NRR/DORL 415-1547 | |
| References | |
| TAC ME0225, TAC ME0226 | |
| Download: ML091260242 (4) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 May 11, 2009 Mr. Charles G. Pardee President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
BRAIDWOOD STATION, UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION RELATED TO RISK-INFORMED RELIEF REQUEST 13R-01 (TAC NOS. ME0225 AND ME0226)
Dear Mr. Pardee:
By letter to the Nuclear Regulatory Commission (NRC) dated December 10, 2008, (Agencywide Documents Access and Management System Accession No. ML083460590), Exelon Generation Company, LLC (the licensee) submitted relief request 13R-01 to request authorization to use a risk-informed inservice inspection program as an alternative to the examination program of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code,Section XI, 2001 Edition through the 2003 Addenda for examination category B-F, B-J, C-F-1, and C-F-2 pressure retaining piping welds.
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 (RAI). Your staff has agreed to provide a response to this RAI within 60 days after the date of this letter.
The NRC staff considers that timely responses to RAls help ensure sufficient time is available for staff review and contribute toward the NRC's goal of efficient and effective use of staff resources. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-1547.
Sincerely,
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Mar all J. David, Senior Projec Pia 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
REQUEST FOR ADDITIONAL INFORMATION BRAIDWOOD STATION, UNITS 1 AND 2 DOCKET NOS. STN 50-456 AND STN 50-457 By letter to the Nuclear Regulatory Commission (NRC) dated December 10, 2008 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML083460590), Exelon Generation Company, LLC, submitted relief request 13R-01 for the proposed third inspection interval, risk-informed inservice inspection (RI-ISI) program at Braidwood Station, Units 1 and 2.
The December 10, 2008, letter requested authorization to use a RI-ISI program as an alternative to the examination program of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI, 2001 Edition through the 2003 Addenda for examination category B-F, B-J, C-F-1, and C-F-2 pressure retaining piping welds. To complete its review of relief request 13R-01, the NRC staff requests the following additional information.
- 1.
The relief request includes the following paragraph:
"The Risk Impact Assessment completed as part of the original baseline RI-ISI Program was an implementation/transition check on the initial impact of converting from a traditional ASME Section XI program to the new RI-ISI methodology. For the Third Interval lSI update, there is no transition occurring between two different methodologies, but rather, the currently approved RI-ISI methodology and evaluation will be maintained for the new interval."
The NRC staff does not agree with the implication that, if there is no change in methodology, the change in risk assessment is not part of the living process.
Furthermore, the submittal is requesting relief to implement a RI-ISI program instead of an ASME program for the third interval, so there is a change from the methodology that would normally be used (Le., without a relief request). Regulatory Guide 1.178, Standard Review Plan 3.9.8, and Electrical Power Research Institute Topical Report 112657 (Refs.
1, 2, and 3) require an evaluation of the change in risk arising from the proposed change in the lSI program. Please provide an estimate of the potential change in risk between the RI-ISI program proposed for implementation in the third interval and the ASME Section XI requirements, which existed prior to the implementation of the first RI-ISI program.
- 2.
The relief request states:
"As an added measure of assurance, any new systems, portions of systems, or components being included in the RI-ISI program for the Third Inspection Interval will be added to the Risk Impact Assessment performed during the previous interval. These components will be addressed within the evaluation at the start of the new interval to assure that the new Third Inspection Interval RI-ISI element selection provides an acceptable overall change-in-risk 0.0" The evaluations described above should have already been performed and the results of the evaluations incorporated into the analysis that forms the basis of the relief request.
ENCLOSURE
-2 Please provide a brief description of these evaluations and an overview of the results.
- 3.
The relief request states:
"These portions of the RI-ISI Program have been and will continue to be reevaluated and revised as major revisions of the site PRA occur and modifications to plant configurations are made.... The Consequence Evaluation, Degradation Mechanism Assessment, Risk Ranking, and Element Selection steps encompass the complete living program process Please provide the date of the last reevaluation and revision that is described above and a brief description of the results of the reevaluations and revisions undertaken at that date. In addition, please explain how modifications to the units since the date of the last reevaluation and revision may impact the RI-ISI program.
- 4.
Please explain any changes that were made to the highest estimates in the high category and, if applicable, specify medium consequence segments that moved to the high category.
- 5.
Because the RI-ISI program is a living program, please describe substantive changes to the current RI-ISI program from that submitted in the relief request for the second lSI interval, dated October 16, 2000 (ADAMS Accession No. ML003761986), as a result of industry and plant operating experience. Items discussed in Sections 4.0 and 5.0 of of the December 10, 2008, relief request do not need to be reiterated.
- 6.
Table IWB-2500-1 of ASME Code Section XI, 2001 Edition with 2003 Addenda requires volumetric and/or surface examination of all Category B-F or B-J Pressure Retaining Dissimilar Metal Welds greater than NPS 1. Based on findings of primary water stress corrosion cracking in Alloy 82/182 dissimilar metal welds, please provide the following information on inspection plans for these welds.
- a. How many Alloy 82/182 welds are selected for examination?
- b. What examination method(s) are being employed?
- c. What is the frequency of examination?
- d. What is the disposition of limited <<90 percent) examinations?
- 7.
Please provide a list of the specific welds that are selected for examination in the third lSI interval.
- a. If the welds selected for examination are different than those selected for the second lSI interval, please describe the reasons for the selections.
- 8.
Please provide a list of any augmented inspection programs which have been subsumed into the RI-ISI program or added since the second lSI interval RI-ISI program was instituted.
May 11, 2009 Mr. Charles G. Pardee President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
BRAIDWOOD STATION, UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION RELATED TO RISK-INFORMED RELIEF REQUEST 13R-01 (TAC NOS. ME0225 AND ME0226)
Dear Mr. Pardee:
By letter to the Nuclear Regulatory Commission (NRC) dated December 10, 2008, (Agencywide Documents Access and Management System Accession No. ML083460590), Exelon Generation Company, LLC (the licensee) submitted relief request 13R-01 to request authorization to use a risk-informed inservice inspection program as an alternative to the examination program of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code,Section XI, 2001 Edition through the 2003 Addenda for examination category B-F, B-J, C-F-1, and C-F-2 pressure retaining piping welds.
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 (RAI). Your staff has agreed to provide a response to this RAI within 60 days after the date of this letter.
The NRC staff considers that timely responses to RAls help ensure sufficient time is available for staff review and contribute toward the NRC's goal of efficient and effective use of staff resources. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-1547.
Sincerely, IRA!
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:
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.IPatel, NRR NRRRidsNrrDorlDpr Resource RidsOgcRp Resource ADAMS Accession Number* ML091260242
- Date of RAI Memo NRR-088 OFFICE LPL3-2/PM LPL3-2/LA DRAlAPLNBC DCI/CPNB/BC LPL3-2/BC NAME MDavid THarris DHarrison*
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DATE 517109 517109 4/20109 4/24/09 5/11/09 OFFICIAL RECORD COpy