ML15140A192

Summary of Telephone Conference Call Held on May 13, 2015, Between the U.S. Nuclear Regulatory Commission and Exelon Generation Co., LLC, Concerning Requests for Additional Information, Set 2 Pertaining to the Lasalle County Station License

ML15140A192
Person / Time
Site:	LaSalle
Issue date:	06/08/2015
From:	Jeffrey Mitchell License Renewal Projects Branch 1
To:	Office of Nuclear Reactor Regulation
Mitchell J, NRR/DLR, 415-3019
References
DLR-15-0273, TAC MF5346, TAC MF5347
Download: ML15140A192 (9)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 June 8, 2015 LICENSEE: Exelon Generation Co., LLC FACILITY: LaSalle County Station, Units 1 and 2

SUMMARY

OF TELEPHONE CONFERENCE CALL HELD ON MAY 13, 2015, BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION AND EXELON GENERATION CO., LLC, CONCERNING REQUESTS FOR ADDITIONAL INFORMATION, SET 2 PERTAINING TO THE LASALLE COUNTY STATION LICENSE RENEWAL APPLICATION (TAC NOS. MF5347 AND MF5346)

The U.S. Nuclear Regulatory Commission (NRC or the staff) and representatives of Exelon Generation Co., LLC (Exelon or the applicant) held a telephone conference call on May 13, 2015, to discuss and clarify the staffs draft requests for additional information (DRAIs) provided in Enclosure 2 concerning the LaSalle County 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 DRAIs discussed with the applicant, including a brief description on the status of the items.

The applicant had an opportunity to comment on this summary.

Sincerely,

/RA/

Jeffrey S. Mitchell, Project Manager Projects Branch 1 Division of License Renewal Office of Nuclear Reactor Regulation Docket Nos. 50-373 and 50-374

Enclosures:

1. List of Participants

2. Summary of Telephone Conference Call cc: Listserv

ML15140A192 *Concurred via e-mail OFFICE LA:DLR PM:RPB1:DLR PM:RPB1:DLR BC:RPB1:DLR PM:RPB1:DLR NAME YEdmonds JMitchell RPlasse YDiaz-Sanabria JMitchell DATE 6/ 4 /15 6/ 4 /15 6/ 4 /15 6/ 5 /15 6/ 8 /15

SUMMARY

OF TELEPHONE CONFERENCE CALL HELD ON MAY 13, 2015, BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION AND EXELON GENERATION CO., LLC, CONCERNING REQUESTS FOR ADDITIONAL INFORMATION, SET 2 PERTAINING TO THE LASALLE COUNTY STATION LICENSE RENEWAL APPLICATION (TAC NOS. MF5347 AND MF5346)

DISTRIBUTION:

E-MAIL:

PUBLIC RidsNrrDlr Resource RidsNrrDlrRpb1 Resource RidsNrrDlrRpb2 Resource RidsNrrDlrRerb Resource RidsNrrDlrRarb Resource RidsNrrDlrRasb Resource RidsNrrDlrRsrg Resource RidsNrrPMLaSalle Resource J. Mitchell R. Plasse D. Drucker B. Wittick J. Wachutka, OGC D. McIntyre, OPA M. Kunowski, RIII V. Mitlyng, RIII P. Chandrathil, RIII H. Logaras, RIII C. Lipa, RIII S. Sheldon, RIII R. Ruiz, RIII J. Robbins, RIII

TELEPHONE CONFERENCE CALL LASALLE COUNTY STATION, UNITS 1 AND 2 LICENSE RENEWAL APPLICATION LIST OF PARTICIPANTS MAY 13, 2015 PARTICIPANTS AFFILIATION Jeffrey Mitchell U.S. Nuclear Regulatory Commission (NRC)

Seung Min NRC Bill Holston NRC Chris Wilson Exelon Generation Co., LLC (Exelon)

John Hufnagel Exelon Shannon Rafferty-Czincila Exelon Pete Tamburro Exelon Mark Miller Exelon Jim Jordan Exelon Paul Weyhmuller Exelon ENCLOSURE 1

SUMMARY

OF TELEPHONE CONFERENCE CALL LASALLE COUNTY STATION, UNITS 1 AND 2 LICENSE RENEWAL APPLICATION MAY 13, 2015 The U.S. Nuclear Regulatory Commission (NRC or the staff) and representatives of Exelon Generation Co., LLC (Exelon or the applicant) held a telephone conference call on May 13, 2015, to discuss and clarify the following draft requests for additional information (DRAIs) concerning the LaSalle County Station (LSCS), Units 1 and 2 license renewal application (LRA).

DRAI B.2.1.7-1

Background:

Generic Aging Lessons Learned (GALL) Report aging management program (AMP) XI.M7, BWR Stress Corrosion Cracking, states that the program to manage intergranular stress corrosion cracking (IGSCC) in BWR coolant pressure boundary piping is delineated in NUREG-0313, Revision 2 and NRC Generic Letter (GL) 88-01 with its Supplement 1. The detection of aging effects program element of GALL Report AMP XI.M7 also states that modifications of the extent and schedule of inspection in NRC GL 88-01 are allowed in accordance with the inspection guidance in staff-approved BWRVIP-75-A.

LRA Section B.2.1.7 states that the BWR Stress Corrosion Cracking AMP is consistent with GALL Report AMP XI.M7. The LRA also states that hydrogen water chemistry and noble metals chemical addition have been implemented to further reduce susceptibility of piping systems exposed to reactor coolant to stress corrosion cracking.

The LRA further indicates that welds classified as Category A (resistant materials) are subsumed into the Risk-Informed Inservice Inspection (RI-ISI) program in accordance with staff-approved EPRI Topical Report TR-112657, Revision B-A, Final Report, Revised Risk-Informed Inservice Inspection Evaluation Procedure, dated December 1999. During the audit, the staff noted that LSCS implemented risk-informed inservice inspection for the current (third) inservice inspection interval through the relief request process as approved in the NRC letter dated April 29, 2008 (ADAMS Accession No. ML080940215).

Issue:

The staff noted that the inspection extent for Category A welds, which are subsumed in the RI-ISI, may not be consistent with the guidance provided in GL 88-01 and BWRVIP-75-A since the RI-ISI adopts a risk-based selection process. Therefore, additional information is necessary to confirm whether the program is adequate to manage cracking due to IGSCC for Category A welds.

Request:

1. Clarify whether the applicants inspection extent for Category A welds, subsumed in the RI-ISI, is consistent with the guidance in GL 88-01 and BWRVIP-75-A.

ENCLOSURE 2

2. If the inspection extent for Category A welds is different from the guidance in GL 88-01 and BWRVIP-75-A, provide the following information:

a. Clarification as to why the inspection extent for Category A welds is not identified as a program exception.

b. Justification for why the program is adequate to manage the aging effect of IGSCC for Category A welds, and an assessment of plant-specific operating experience to support the justification.

Teleconference Summary:

The staff clarified a question regarding the extent of the information being requested. The applicant agreed to provide the requested information as written.

DRAI B.2.1.7-2:

Background:

LRA Section B.2.1.7 states that LaSalles BWR Stress Corrosion Cracking AMP is consistent with GALL Report AMP XI.M7, BWR Stress Corrosion Cracking.

GALL Report AMP XI.M7, BWR Stress Corrosion Cracking, states that the program to manage IGSCC in BWR coolant pressure boundary piping is delineated in NUREG-0313, Revision 2 and NRC GL 88-01 with its Supplement 1. The detection of aging effects program element of GALL Report AMP XI.M7 also states that modifications of the extent and schedule of inspection in NRC GL 88-01 are allowed in accordance with the inspection guidance in staff-approved BWRVIP-75-A.

GL 88-01 Category B and C welds are made of non-resistant materials to IGSCC. A stress improvement process was applied on Category B welds and Category C welds within the first 2 years of operation and after the first 2 years of operation, respectively. During the audit, the staff noted that the following onsite document describes inspection schedules and selections for Category B and C welds during the third 10 year inspection interval.

• LaSalle County Nuclear Power Station Units 1 & 2 ISI Selection Document Third Ten-Year Inspection Interval, Revision 1, March 31, 2011.

Issue:

The staff also noted that the referenced onsite document indicates that inspection selections for Unit 2 Categories B and C welds are as follows:

• For Unit 2 Category B welds, the number of welds to be inspected in accordance with BWRVIP-75-A (i.e., 25 percent every 10 years) is 33.5; however, the number of welds selected for inspection is only 25.

• For Unit 2 Category C welds, the number of welds to be inspected in accordance with BWRVIP-75-A (i.e., 25 percent every 10 years) is two; however, the number of welds selected for inspection is only one.

The inspection plan for the third 10-year interval indicates that in each of Categories B and C the number of welds selected for inspection at Unit 2 is less than that to be inspected in accordance with BWRVIP-75-A. Therefore, additional information is necessary to confirm the consistency of the program with GALL Report AMP XI.M7.

Request:

1. Provide justification as to why the inspection plan indicates that the number of Category B welds selected for inspection at LSCS, Unit 2 is less than that to be inspected in accordance with BWRVIP-75-A. In addition, justify why the number of Category C welds selected for inspection at Unit 2 is less than that to be inspected in accordance with BWRVIP-75-A. If the numbers chosen for inspection cannot be justified, adjust the inspection extents for Categories B and C welds in accordance with BWRVIP-75-A.

2. Discuss whether the applicants inspections indicated occurrence of IGSCC in Category B or C welds at LSCS in order to confirm that the plant-specific operating experience supports the adequacy of the inspection frequency and scope.

Teleconference Summary:

The staff clarified a question regarding the second paragraph under the Request section. The staff clarified the intent of the request and indicated that the second paragraph under the Request section would be revised to be more clear in the final RAI.

DRAI B.2.1.7-3:

Background:

LRA Section B.2.1.7 states that the BWR Stress Corrosion Cracking AMP is consistent with GALL Report AMP XI.M7, BWR Stress Corrosion Cracking. The detection of aging effects program element of GALL Report AMP XI.M7 indicates that the inspection extent and schedule are described in NRC GL 88-01 and modifications of the inspection extent and schedule are allowed in accordance with the staff-approved BWRVIP-75-A.

GL 88-01 indicates that examinations performed under the scope of GL 88-01 should comply with the applicable Edition and Addenda of the ASME Code,Section XI, as specified in paragraph (g), "Inservice Inspection Requirements" of 10 CFR 50.55a, Codes and Standards, or as otherwise approved by the NRC. In addition, Information Notice No. 98-42, Implementation of 10 CFR 50.55a(g) Inservice Inspection Requirements, indicates that "essentially 100 percent" of the required examination volume for inservice inspections is defined as more than 90 percent of the specified examination volume.

Issue:

The staff noted that the following inservice inspection summary report for LSCS Unit 2 indicates that the examination coverage of the BWRVIP-75-A inspections on Category B welds was as low as 50 percent.

• Table B of Post-Outage 90-Day ISI Summary Report, May 31, 2013 (ADAMS Accession No. ML13151A451)

The staff needs additional information to determine whether the limited examination coverage of the inspections is adequate to manage cracking due to IGSCC for the welds within the scope of the program.

Request:

1. Provide the average examination coverage of each weld category (i.e., each of Categories A through G) for each unit in order to characterize the overall degree of limited examination coverage. In addition, explain why the examination coverage is limited.

2. Justify why the program is adequate to manage cracking due to IGSCC without additional inspections that will compensate for the limited examination coverage of each weld category during an inspection period (e.g., every 10 years for Category B welds).

Teleconference Summary:

The staff clarified questions regarding the scope of the examination coverage information being requested. The applicant agreed to provide the current planned actions from the Corrective Actions Program and the latest examination results in the response to the final RAI.

DRAI 3.0.3.3.1-2:

Background:

LRA Section B.2.2.1 states that internal coating inspections may be omitted if the degradation of coatings cannot result in downstream effects; however, inspections are conducted if corrosion rates or inspection intervals have been based on the integrity of the coatings. LRA Section B.2.2.1 further states that as an alternative to direct internal visual inspection of the coatings, external wall thickness measurements can be performed to confirm the acceptability of the corrosion rate of the base metal.

The final GALL Report AMP XI.M42 recommends a periodicity and size of inspection for alternative wall thickness measurements, which was not included in the draft GALL Report AMP XI.M42 provided in draft LR-ISG-2013-01, Aging Management of Loss of Coating Integrity for Internal Service Level III (augmented) Coatings. Specifically, the AMP recommends that wall thickness measurements be conducted on a representative sample of components every 10 years, commencing 10 years prior to the period of extended operation.

A representative sample size is 25 percent of accessible external surfaces for heat exchangers, strainers, and tanks; and for piping, 73 1-foot axial length circumferential segments. In addition, the final AMP XI.M42 recommends that the inspection grid size be the same as that for flow accelerated corrosion inspections.

Issue:

LRA Section B.2.2.1 does not state the periodicity and size of inspection for alternative wall thickness measurements.

Request:

State the periodicity and size of inspection for alternative wall thickness measurements.

Teleconference Summary:

The staff clarified a question regarding whether the RAI is requesting information beyond that discussed in the Interim Staff Guidance (ISG). The applicant agreed to provide a response to this request that is in accordance with the ISG.