ML15029A694
| ML15029A694 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 02/24/2015 |
| From: | Robinson L License Renewal Projects Branch 1 |
| To: | Exelon Generation Co |
| Robinson L, DLR/RPB1, 301-415-4115 | |
| References | |
| TAC MF1879, TAC MF1880, TAC MF1881, TAC MF1882 | |
| Download: ML15029A694 (7) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 February 24, 2015 LICENSEE:
Exelon Generation Company, LLC FACILITY:
Byron Station, Units 1 and 2 Braidwood Station, Units 1 and 2
SUBJECT:
SUMMARY
OF TELEPHONE CONFERENCE CALL HELD ON JANUARY 7, 2015, BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION AND EXELON GENERATION COMPANY, LLC CONCERNING DRAFT REQUEST FOR ADDITIONAL INFORMATION, SET 45, PERTAINING TO THE BYRON STATION AND BRAIDWOOD STATION, LICENSE RENEWAL APPLICATION (TAC NOS. MF1879, MF1880, MF1881, MF1882)
The U.S. Nuclear Regulatory Commission (NRC or the staff) and representatives of Exelon Generation Company, LLC (Exelon or the applicant), held a telephone conference call on January 7, 2015, to discuss and clarify the staffs draft request for additional information (DRAI),
Set 45, concerning the Byron Station, Units 1 and 2, and the Braidwood Station, Units 1 and 2, license renewal application. The telephone conference call was useful in clarifying the intent of the staffs DRAIs.
provides a listing of the participants, and Enclosure 2 contains the DRAI discussed with the applicant, including a brief description on the status of the items.
The applicant had an opportunity to comment on this summary.
/RA/ (John Daily for)
Lindsay Robinson, Project Manager Projects Branch 1 Division of License Renewal Office of Nuclear Reactor Regulation Docket Nos. 50-454, 50-455, 50-456, and 50-457
Enclosures:
- 1. List of Participants
- 2. List of Draft Request for Additional Information cc w/encls: Listserv
- John Daily for OFFICE LA:RPB1:DLR PM:RPB1:DLR BC:RPB1:DLR PM:RPB1:DLR NAME YEdmonds LRobinson*
YDiazSanabria LRobinson*
DATE 2/12/15 2/19/15 2 /19/15 2 /24/15
SUBJECT:
SUMMARY
OF TELEPHONE CONFERENCE CALL HELD ON JANUARY 7, 2015, BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION AND EXELON GENERATION COMPANY, LLC CONCERNING DRAFT REQUEST FOR ADDITIONAL INFORMATION, SET 45, PERTAINING TO THE BYRON STATION AND BRAIDWOOD STATION, LICENSE RENEWAL APPLICATION (TAC NOS. MF1879, MF1880, MF1881, MF1882)
DISTRIBUTION EMAIL:
PUBLIC RidsNrrDlr Resource RidsNrrDlrRpb1 Resource RidsNrrDlrRarb Resource RidsNrrDlrRasb Resource RidsOgcMailCenter RidsNrrPMByron Resource RidsNrrPMBraidwood Resource LRobinson DMcIntyre, OPA EDuncan, RIII JBenjamin, RIII AGarmoe, RIII JMcGhee, RIII JRobbins, RIII VMitlyng, RIII PChandrathil, RIII
ENCLOSURE 1 TELEPHONE CONFERENCE CALL BYRON STATION, UNITS 1 AND 2, AND BRAIDWOOD STATION, UNITS 1 AND 2 LICENSE RENEWAL APPLICATION LIST OF PARTICIPANTS January 7, 2015 PARTICIPANTS AFFILIATIONS Lindsay Robinson U.S. Nuclear Regulatory Commission (NRC)
Bart Fu NRC Roger Kalikian NRC John Hufnagel Exelon Generating Company, LLC (Exelon)
Al Fulvio Exelon Don Warfel Exelon Albert Piha Exelon Gary Becknell Exelon Casey Muggleston Exelon Don Brindle Exelon Ralph Wolen Exelon
ENCLOSURE 2 DRAFT REQUEST FOR ADDITIONAL INFORMATION BYRON STATION, UNITS 1 AND 2, AND BRAIDWOOD STATION, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION January 7, 2015 The U.S. Nuclear Regulatory Commission (NRC or the staff) and representatives of Exelon Generation Company, LLC (Exelon or the applicant), held a telephone conference call on January 7, 2015, to discuss and clarify the following draft request for additional information (DRAI), Set 45, concerning the Byron Station, Units 1 and 2, and the Braidwood Station, Units 1 and 2, license renewal application (LRA).
DRAI B.2.1.30-6 Applicability:
Braidwood Station (Braidwood), Units 1 and 2
Background:
By letter dated October 31, 2014, the applicant provided a response to the staffs request for additional information (RAI) B.2.1.24-1a (ADAMS Accession No. ML14304A345). In the response, the applicant described problems encountered during the latest flux thimble tube inspections. Specifically, the applicant failed to obtain any useful data for any most of the tubes it attempted to inspect. The response failed to provide an adequate root cause for the issues encountered during the last outages for Braidwood, Units 1 and 2. In addition, the response failed to provide a technical basis for the adequacy of the program.
By letter dated November 22, 2014, the applicant supplemented its response to RAI B.2.1.24-1a (ADAMS Accession No. ML14330A480). The supplemental response, in part, provided a license renewal commitment to replace flux thimble tubes every three refueling cycles if eddy current data is not obtained in accordance with the Flux Thimble Tube Inspection Program.
Issue:
In the license renewal application (LRA), the applicant stated that the existing Flux Thimble Tube Inspection Program is consistent with Generic Aging Lessons Learned (GALL) Report aging management program (AMP) XI.M37, Flux Thimble Tube Inspection. However, based on the available information, it is apparent that the applicant is currently not able to perform inspections of or obtain usable data from the thimble tubes. Therefore, the applicants program does not meet guidance provided in GALL Report AMP XI.M37. Specifically, in Element 3, parameters monitored or inspected, the applicants program does not provide adequate parameters monitored or inspected; in Element 4, detection of aging effects, the applicants program does not provide adequate detection of aging effect (wear); in Element 5, monitoring and trending, the applicants program does not provide adequate monitoring and trending; and in Element 7, corrective actions, the applicants corrective actions have not identified the causal factors of its inspection problems, and the implemented corrective measures have not mitigated the inspection problems. Therefore, the staff is not certain why the applicant has not identified these as exceptions to the GALL Report AMP XI.M37.
In addition, the staff noted in the applicants RAI response dated June 9, 2014, that one tube installed in spring of 2009 experienced 37 percent wear per cycle during the fall 2010 outage at Unit 1. The tube was removed from service in 2012 after only two cycles of service. The staff also noted in the same response that a tube experienced 35 percent wear per cycle at Unit 2 in spring of 2011 outage. Based on plant-specific operating experience at Braidwood provided by the applicant, it appears that most tubes will last for more than three cycles and still meet the acceptance criteria of 80 percent tube wear. However, the staff is concerned that the outliers, for example, locations that can experienced higher wear of 35 percent or 37 percent per cycle, will not last for three cycles. In addition, there have been instances when a location that had historically experienced low wear for many cycles had unusually higher wear rates in a subsequent cycle. Therefore, the staff is concerned that in these instances, degraded tubes would not be identified without successful inspections and that acceptance criteria may not be met at all times for all locations.
Furthermore, the staff noted that the applicant had prior issues related to obtaining wear data or completing scheduled inspections, which were entered in the applicants corrective action program to prevent recurrence. The applicant speculated possible casual factors in its response dated October 31, 2014, and stated that it may consider several additional corrective actions. However, based on the latest information, it appears the problems associated with successful completion of eddy current examinations (i.e., getting usable wear data) have worsened.
Finally, the staff noted that if movable detector(s) get stuck, the isolation valves would not be able to isolate the affected flux thimble tube(s) in the event of leakage due to wear.
Request:
- 1) Review the current Flux Thimble Tube Inspection Program for Braidwood, and identify all exceptions to GALL Report AMP XI.M37, Flux Thimble Tube Inspection. If necessary, provide a plant-specific AMP, which addresses the higher than usual wear rates, and justify the programs long-term viability based on the possibility of not obtaining any inspection data on wear. Describe the technical basis that tube wear acceptance criteria are met and that the program is adequate.
- 2) Identify all cases of higher wear (27 percent per cycle or more). Justify the adequacy of the program if tube replacement is performed every three cycles with consideration of the operating experience of high wear rates as discussed above. Provide information on all instances when a tube was removed from service after three or less cycles or service.
- 3) Justify why the historical wear rates would be applicable during the period of extended operation if additional examinations are not performed or did not provide usable data, taking into consideration that wear rates can change.
- 4) Provide a root cause analysis which adequately identifies the problems encountered during the recent inspections; discuss corrective measures which will be implemented to address the problems.
- 5) Provide information in regards to instances when detectors became stuck at Braidwood Units 1 and 2. Explain how leakage would be isolated if detectors are stuck when a flux thimble tube develops a leak.
Discussion: The applicant requested clarification of the staffs concerns. The staff made minor edits, as indicated above. New information is depicted with an underline, and deleted information is depicted with a strikethrough.