ML14128A334

Staff Assessment of the Seismic Walkdown Report Supporting Implementation of Near-term Task Force Recommendation 2.3 Related to the Fukushima DAI-ICHI Nuclear Power Plant Accident

ML14128A334
Person / Time
Site:	LaSalle
Issue date:	05/29/2014
From:	Blake Purnell Plant Licensing Branch III
To:	Pacilio M Exelon Generation Co
Blake Purnell, NRR/DORL 415-1380
References
TAC MF0136, TAC MF0137
Download: ML14128A334 (21)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 May 29, 2014 Mr. Michael J. Pacilio Senior Vice President Exelon Generation Company, LLC President and Chief Nuclear Officer (CNO) 4300 Winfield Road Warrenville, I L 60555

SUBJECT:

LASALLE COUNTY STATION, UNITS 1 AND 2- STAFF ASSESSMENT OF THE SEISMIC WALKDOWN REPORT SUPPORTING IMPLEMENTATION OF NEAR-TERM TASK FORCE RECOMMENDATION 2.3 RELATED TO THE FUKUSHIMA DAI-ICHI NUCLEAR POWER PLANT ACCIDENT (TAC NOS.

MF0136 AND MF0137)

Dear Mr. Pacilio:

On March 12, 2012, 1 the U.S. Nuclear Regulatory Commission (NRC) issued a letter requesting information pursuant to Title 10 of the Code of Federal Regulations, Paragraph 50.54(f)

(50.54(f) letter). The 50.54(f) letter was issued to power reactor licensees and holders of construction permits requesting addressees to provide information to support the NRC staff's evaluation of regulatory actions to be taken in response to lessons learned from Japan's March 11, 2011, Great Tohoku Earthquake and subsequent tsunami. The request addressed the methods and procedures for nuclear power plant licensees to conduct seismic and flooding hazard walkdowns to identify and address degraded, nonconforming, or unanalyzed conditions through the corrective action program, and to verify the adequacy of the monitoring and majntenance procedures.

By letter dated November 27, 2012, as supplemented by letters dated April 30 and November 27, 2013, 2 Exelon Generation Company, LLC (Exelon) submitted seismic walkdown reports for LaSalle County Station, Units 1 and 2, as requested in Enclosure 3, "Recommendation 2.3: Seismic," of the 50.54(f) letter. By letter dated September 16, 2013, 3 Exelon provided additional information on the completion of inaccessible items and the substitutions made to the list of inaccessible items in order to complete all walkdowns and submit the final walkdown reports by August 28, 2014.

The NRC staff reviewed the information provided and, as documented in the enclosed staff assessments, determined that sufficient information was provided to be responsive to of the 50.54(f) letter. The staff acknowledges that a supplemental letter will be provided by August 28, 2014, addressing the remaining inaccessible items consistent with the regulatory commitment.

1 Agencywide Document Access and Management System (ADAMS) Accession No. ML12053A340 2

ADAMS Accession No. ML123530341, ML131920489 (Unit 2 only), and ML133318501, respectively 3

ADAMS Accession No. ML13260A083

M. Pacilio If you have any questions, please contact me at 301-415-1380 or by e-mail at Blake. Purnell@nrc.gov.

Sincerely, Blake Purnell, Project Manager Plant Licensing 111-2 and Planning and Analysis Branch Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-373 and 50-37 4

Enclosures:

1. Staff Assessment of Seismic Walkdown Report for Unit 1

2. Staff Assessment of Seismic Walkdown Report for Unit 2 cc w/encl: Distribution via Listserv

STAFF ASSESSMENT OF SEISMIC WALKDOWN REPORT NEAR-TERM TASK FORCE RECOMMENDATION 2.3 RELATED TO THE FUKUSHIMA DAI-ICHI NUCLEAR POWER PLANT ACCIDENT

.EXELON GENERATION COMPANY, LLC

• LASALLE COUNTY STATION, UNIT 1 DOCKET NO. 50-373

1.0 INTRODUCTION

On March 12, 2012, 1 the U.S. Nuclear Regulatory Commission (NRC) issued a letter requesting infornieition pursuant to Title 10 of the Code of Federal Regulations (1 0 CFR), Paragraph 50.54(f) (50.54(f) letter) to all power reactor licensees and holders of construction permits in

\ active or deferred status. The request was part of the implementation of lessons learned from the accident at the Fukushima Dai-i"chi nuclear power plant. Enclosure 3, "Recommendation 2.3: Seismic," to the 50.54(f) letter requested licensees to conduct seismic walkdowns*to identify and address degraded, nonconforming, or unanalyzed conditions using the corrective action program (CAP), verify the adequacy of monitoring and maintenance procedures, and report the results to the NRC.

Enclosure 3 of the 50.54(f) letter requested licensees to provide the following:.

a. Information concerning the plant-specific hazard licensing bases and a description of the protection and mitigation features considered in the licensing basis evaluation.

b: Information related to the implementation of the walkdown process.

c. A list of plant-specific vulnerabilhies identified by the Individual Plant Examination of External Events (IPEEE) program and a description of the actions taken to eliminate or reduce them. *

d. Results of the walkdown including key findings and identified degraded, nonconforming, or unanalyzed conditions.

e. Any planned or newly installed protection and mitigation features.

f. Results and any subsequent actions taken in response to the peer review.

In accordance with the 50.54(f) letter, Enclosure 3, Required Respons~ Item 2, licensees were required to submit a response within 180 days of the NRC's endorsement of-the seismic walkdown process. By letter dated May 29, 2012, 2 the Nuclear Energy Institute submitted

~ ,*

1 Agencywide Document Access and Management System (ADAMS) Accession No. ML12053A340.

2 ADAMS Package Accession No. ML121640872..

• Enclosure 1

Electric Powe*r Research Institute document 1025286, "Seismic Walkdown Guidance for Resolution of Fukushima Near-Term Task Force Recommendation 2.3: Seismic," (walkdown guidance) to the NRC staff to consider for endorsement. By letter dated May 31, 2012, 3 the staff endorsed the walkdown guidance.

• By letter dated November 27, 2012, 4 Exelon Generation Company, LLC (the licensee) provided a seismic walkdown report in response to Enclosure 3 of the 50.54(f) letter, Required Response Item 2, for the LaSalle County Station, Unit 1 (LCS1). By letter dated S.eptember 16, 2013, 5 the licensee updated its commitment for completing and reporting the delayed inspections of remaining inaccessible items by August 28, 2014. The NRC staff reviewed the walkdown report ahd determined that additional supplemental information would assist the staff in completing its review. By letter dated November 1, 2013, 6 the NRC staff requested additional information to gain a better understanding of the processes and procedures used by the licensee in conducting the walkdowns and walk-bys. The licensee responded to the NRC staff request by letter dated November 27, 2013. 7 The NRC staff evaluated the licensee's submittals to determine if the information provided in the walkdown report met the intent of the walkdown guidance and if the licensee responded appropriately to Enclosure 3 of the 50.54(f) letter.

2.0 REGULATORY EVALUATION

The structures, systems, and components (SSCs) important to safety in operating nuclear power plants are designed either in accordance with, or meet the intent of Appendix A to 10 CFR Part 50, General Design Criteria (GDC) 2, "Design Bases for Protection Against Natural Phenomena," and Appendix A to 10 CFR Part 100, "Reactor Site Criteria." GDC 2 states that SSCs important to safety at nuclear power plants shall be designed to withstand the effects of natural phenomena such as earthquakes, tornadoes, hurricanes, floods, tsunami, and seiches without loss of capability to perform their safety functions.

For initial licensing, each licensee was required to develop and maintain design bases that, as defined by 10 CFR 50.2, "Definitions," identify the specific functions that an SSC of a facility must perform, and the specific values or ranges of values chosen for controlling parameters as reference bounds fo~ the design.

The design bases for the SSCs reflect appropriate consideration of the most severe natural phenomena that have been historically reported for the site an*d surrounding area. The design bases also reflect sufficient margin to account for the limited accuracy, quantity, and period of time in which the historical data have been accumulated.

The current licensing basis is the set of NRC requirements applicable to a specific plant, including the licensee's docketed commitments for ensuring compliance with, and operation 3

ADAMS Accession No. ML12145A529 4

ADAMS Package Accession No. ML123530341 5

ADAMS Accession No. ML13260A083 6

ADAMS Accession No. ML133048418 7

ADAMS Accession No. ML133318501

within, applicable NRC requirements and the plant-specific design basis, including all modifications and additions to such commitments over the life of the facility operating license.

3.0 TECHNICAL EVALUATION

3.1 Seismic Licensing Basis Information The licensee provided information on the plant-specific licensing basis for the Seismic Category I SSCs for LCS1 in Section 2.0 of the walkdown report. Consistent with the walkdown guidance, the NRC staff noted that the report includes a summary of the safe-shutdown earthquake (SSE) and a description of the codes, standards, and methods that were used in the design of the Seismic Category I SSCs for meeting the plant-specific seismic licensing bpsis requirements. The staff reviewed.Section 2.0 of the walkdown report focusing on the summary of the SSE and the design codes used in the design.

Based on the NRC staff's review, the staff concludes that the licensee has provided information on the plant-specific seismic licensing basis and a description of the protection and mitigation features considered in the licensing bases evaluation consistent with Section 8, "Submittal Report," of the walkdown guidance.

3.2 Seismic Walkdown Methodology Implementation Section 2, "Personnel Qualifications"; Section 3, "Selection of SSCs"; Section 4, "Seismic Walkdowns and Area Walk-Bys"; and Section 5, "Seismic Licensing Basis Evaluations," of the walkdown guidance provide information to licensees regarding the implementation of an appropriate seismic walkdown methodology. By letter dated July 10, 2012, 8 the licensee confirmed that it would use the walkdown guidance to perform the seismic walkdowns at LCS1.

The walkdown report dated November 27, 2012, did not identify deviations from the walkdown guidance.

The NRC staff reviewed the following sections of the walkdown methodology implementation provided in the walkdown report:

• Personnel Qualifications

• Development of the Seismic Walkdown Equipment Lists (SWELs)

• Implementation of the Walkdown Process

• Licensing Basis Evaluations and Results )

3.2.1 Personnel Qualifications Section 2, "Personnel Qualifications," of the walkdown guidance provides licensees with qualification information for personnel involved in the conduct of the seismic walkdowns and area walk-bys.

8 ADAMS Accession No. ML12193A081.

The NRC staff reviewed the information provided in Section 3 and Appendix A of the walkdown report, which includes information on the walkdown personnel and their qualifications.

Specifically, the staff reviewed the summary of the background, experience, and level of involvement for the following personnel involved in the seismic walkdown activities: equipment selection personnel, seismic walkdown engineers (SWEs), licensing basis reviewers, IPEEE reviewers, peer review team, and operations staff.

Based on the review of the licensee's submittals, the NRC staff concludes that those involved in the seismic walkdown activities have the appropriate seismic background, knowledge and experience, as specified in Section 2 of the walkdown guidance.

3.2.2 Development of the SWELs Section 3,"Selection of SSCs," of the walkdown guidance provides information to licensees for selecting the SSCs that should be placed on the SWELs, so that they can be walked down by qualified personnel.

The NRC staff reviewed the overall process used by the licensee to develop the LCS1 base list, SWEL 1 (sample list of designated safety functions equipment), and SWEL 2 (sample list of spent fuel pool (SFP)- related equipment). The licensee provided the base list, SWEL 1, and SWEL 2 in Appendix B of the walkdown report and discussed these lists in Section 4.2.1 of the walkdown report. The licensee divided base list 1 into two parts-base list 1a for components exclusive to Unit 1, and base list 1b for components common to Units 1 and 2.

The_overall equipment selection process followed the screening process shown in Figures 1-1 and 1-2 of the walkdown guidance. Based on Appendix B Tables B-3 and B-4 of the walkdown report, LCS1 SWELs 1 and 2 meet the inclusion requirements of the walkdown guidance.

-Specifically, the following attributes were considered in the sample selection:

• ' A variety of systems, equipment and environments

• IPEEE equipment

• Major new or replacement equipment

• Risk considerations

'\

It is possible that some classes of equipment will not be represented on the SWEL due to individual plant configurations and the walkdown guidance screening process followed to select the final SWEL equipment. The walkdown guidance recognizes this is due to the equipment not being present in the plant (e.g., some plants generate direct current power using inverters and, therefore, do not have motor generators) or the equipment being screened out during the screening process (described in Section 3 of the walkdown guidance). Based on the information provided, the NRC staff noted that a detailed explanation was provided justifying cases where specific classes of equipment were not included as part of the SWEL, and concludes that these exclusions are acceptable.

The NRC staff also noted that a rapid drain-down list was not included as part of the SWEL 2, as described in Section 3 of the guidance. In Section 4.2.2 of the walkdown report, the licensee stated that there are no SFP penetrations below 10 feet above the top of the fuel assemblies.

Based on this, the licensee concluded that there is no potential for rapid drain-down and,

therefore, no items were added to SWEL 2. After reviewing the information provided in this section, the staff concludes that the licensee provided adequate justification for not including rapid drain-down items as part of the SWEL 2 for the LCS1 SFP.

After reviewing SWELs 1 and 2, the NRC staff concludes that the sample of SSCs represents a diversity of cornponent types and assures inclusion of components from critical systems and functions, thereby, meeting the intent of the walkdown guidance. In addition, the staff notes that the equipment selection personnel were appropriately supported by plant operations staff as described in the walkdown guidance.

3.2.3 Implementation of the Walkdown Process Section 4, "Seismic Walkdowns and Area Walk:-Bys," of the walkdown guidance provides information to licensees regarding the conduct of the seismic walkdowns and area walk-bys for each site.

The NRC staff reviewed Section 5 of the walkdown report, which summarizes the results of the seismic walkdowns and area walk-bys, including an overview of the number of items walked down and the number of areas walked-by. The walkdown report states that teams, which consisted of two qualified SWEs, conducted the seismic walkdowns and area walk-bys.

According to the signed seismic walkdown checklists (SWCs) and area walk-by checklists (AWCs), these activities were conducted during the months of September and October of 2012.

The walkdown report also states that the SWEs discussed their observations and judgments

• with each other during the walkdowns. Additionally, the SWEs agreed on the results of their seismic walkdowns and area walk-bys before reporting the results of their review. Appendices C and D of the walkdown report provide the completed SWCs and AWCs, documenting the results for each item of equipment on SWELs 1 and 2 and each area containing SWEL equipment. The licensee used the checklists provided in Appendix C of the walkdown guidance report without modification.

The licensee documented cases of potentially adverse seismic conditions (PASCs) in the checklists for further evaluation. Tables 5-2 and 5-3 of the walkdown report list the conditions, including any PASCs, identified during the seismic walkdowns and the area walk-bys, respectively. The tables describe how each condition was addressed (e.g., placement in the CAP), its resolution, and current status.

By letter dated November 1, 2013, the NRC staff issued two questions in a request for.

additional information (RAI) in order to obtain additional clarification regarding the process followed by the licensee when evaluating_conditions identified in the field during the walkdowns and walk-bys. Specifically, in RAI 1, the staff requested the licensee to provide further explanation regarding how a field observation was determined to be PASC, and to ensure that the basis for determination was addressed using normal plant processes and documented in the walkdown report. In its November 27, 2013, response, the licensee confirmed that observations which could not be readily judged to be acceptable with respect to its current licensing basis during the walkdown, and were not found to be previously evaluated as acceptable conditions through follow-up review of plant documentation, were identified as PASCs and were

documented as issue reports in the LCS1 CAP. The licensee referred to Tables 5-2 and 5-3 of the walkdown report which include conditions identified during the walkdowns and area walk-bys for LCS 1. The licensee also stated that a very conservative position regarding CAP entries was used to identify and document PASCs. The licensee stated that in addition to the items included in Tables 5-2 and 5-3, nonseismic potentially adverse conditions, such as housekeeping and material conditions items, were identified by SWEs and addressed through the CAP. Furthermore, the licensee confirmed that, based on its review of the LCS1 walkdown process and the information submitted in the walkdown reports, that no new conditions were identified that would require an additional supplement or additional CAP entries.

After evaluating the licensee's response and reviewing Tables 5-2 and 5-3 of the walkdown report, the NRC staff concludes that the licensee properly identified and documented the PASCs and that the summary tables provided are complete.

In addition to the information provided above, the NRC staff notes that anchorage configurations were verified to be consistent with existing plant documentation for at least 50 percent of the SWEL items, in accordance with Section 4 of the walkdown guidance.

• Tables E-1 and E-2 of the walkdown report list equipment and areas that were inaccessible during the 180-day period. Table E-1 lists seven SWEL components that were inaccessible at the time of the walkdowns and the planned walkdown completion dates for these components.

Table E-2 lists deferred walkdowns of 18 cabinets that were not internally inspeded. In

• Attachment 4 of the September 16, 2013, letter, the licensee provided a revised list of all remaining SWEL items and internal cabinet inspections. The NRC staff noted that one cabinet of the remaining 18 will not be available for internal inspection due to the extensive disassembly required. The staff concludes that the exclusion of this single piece of equipment is acceptable and maintains the diversity of the equipment classes in the original SWEL.

.In its September 16, 2013, letter, the licensee committed to complete the walkdowns for the limited number of remaining inaccessible items and cabinets by June 1, 2014, and submit the final walkdown report to the NRC by August 28, 2014. The NRC staff concludes that the inaccessible equipment list was developed consistent with the walkdown guidance. The schedule for completion is consistent with the timing of the next scheduled refueling and system outages.

Based on the information provided in the licensee's.submittals, the NRC staff concludes that the licensee's implementation of the walkdown process meets the intent of the walkdown guidance.

3.2.4 Licensing Basis Evaluations and Results Section 5, "Seismic Licensing Basis Evaluations," of the walkdown guidance provides information to licensees regarding the conduct of licensing basis evaluations for items identified during the seismic walkdowns as degraded, nonconforming, or unanalyzed, that might have potential seismic significance.

The NRC staff reviewed Section 6 of the LCS1 walkdown report, which discusses the process for conducting the seismic licensing basis evaluations of the PASCs identified during the seismic walkdowns and area walk-bys. The licensee stated that all questionable conditions identified

during the walkdown were entered into the CAP to be further evaluated and addressed as required. Tables 5-2 and 5-3 ofthe walkdown report list the key licensee findings and provide a complete list of the potentially degraded, nonconforming, or unanalyzed conditions. These tables also describe the actions taken or planned to address these conditions, including the current status of each of the items the licensee entered into the CAP.

The NRC staff reviewed the CAP entries and the description of the actions taken or planned to address potential deficiencies. The staff concludes that the licensee appropriately identified degraded, nonconforming, or unanalyzed conditions and entered them into the CAP, which meets the intent of the walkdown guidance.

3. 2. 5 Conclusion Based on the discussion above, the NRC staff concludes that the licensee's implementation of seismic walkdown methodology meets the intent of the walkdown guidance for personnel qualifications, development of SWELs, implementation of the walkdown process, and seismic licensing basis evaluations.

3.3' Peer Review Section 6, "Peer Review," of the walkdown guidance provides licensees with information regarding the conduct of peer reviews for the activities performed during the seismic walkdowns. Page 6-1 of the walkdown guidance identifies the following activities to be conducted during the peer review process:

• Review the selection of the SSCs included on the SWELs.

• Review a sample of the checklists prepared for the seismic walkdowns and area walk-bys.

• Review the licensing basis evaluations.

• Review the decisions for entering the potentially adverse conditions into the CAP .

.* Review the walkdown report.

• Summarize the results of the peer review process in the walkdown report.

The NRC staff reviewed the information provided in SeCtion 8 and Appendix F of the walkdown report, and the November 27, 2013, letter, which describe the conduct of the peer review. In RAI 2, the staff requested the licensee to provide additional information on the overall peer review process that was followed as part of the walkdown activities. Specifically, the staff requested the licensee to confirm that the activities identified on page 6-1 of the walkdown guidance were assessed and documented in the report. The licensee was also requested to confirm that any individual involved in performing any given walkdown activity was not a peer reviewer for that same activity. In its November 27, 2013, letter, the licensee confirmed that all the activities identified on page 6-1 of the walkdown guidance were included as part of the peer review process and referred to the summary of the peer review activities provided in Appendix F of the walkdown report. In addition, the licensee stated that there were no cases where any peer reviewer reviewed their own work.

The NRC staff reviewed the licensee's summary of each of these activities, which included a discussion of the peer review team members' qualifications and level of involvement, the peer review findings, and resolution of peer review comments. After reviewing the licensee's submittals, the NRC staff concludes that the licensee sufficiently documented the results of the peer review activities and how these reviews affected the work described in the walkdown report.

Based on the discussion above, the NRC staff concludes that the licensee's results of the peer review and subsequent actions taken in response to the peer review meets the intent of Section 6 of the walkdown guidance.

3.4

• IPEEE Information Section 7, "IPEEE Vulnerabilities," of the walkdown guidance provides information to licE}nsees regarding the reporting of the evaluations conducted and actions taken in response to seismic vulnerabilities identified during the IPEEE program. Through the IPEEE program and Generic Letter 88-20, "Individual Plant Examination of External Events for Severe Accident Vulnerabilities,:* licensees previously performed a systematic examination to identify any plant-specific vulnerabilities to severe accidents.

• The licensee provided background information regarding its IPEEE program and referenced several submittals to the NRC. The licensee stated in Section 7 of the walkdown report that "a review of the LaSalle County Nuclear Power Station [IPEEE] Submittal along with the NRC Staff Evaluation Report of the IPEEE found that no vulnerabilities were identified and no plant improvements resulted from the IPEEE program."

Based on the NRC staff's review of Section 7 of the walkdown report, the staff concludes that the licensee's summary of the IPEEE is consistent with and meets the intent of Section 7 of the walkdown guidance.

3.5 Planned Upgrades The licensee did not identify any planned or newly installed protection and mitigation features in the walkdown report.

3.6 NRC Oversight 3.6.1 Independent Verification by Resident Inspectors On July 6, 2012, 9 the NRC issued Temporary Instruction (TI) 2515/188 "Inspection of Near-Term Task Force Recommendation 2.3 Seismic Walkdowns." In accordance with the Tl, NRC inspectors independently verified that the licensee implemented the seismic walkdowns in accordance with the walkdown guidance at LCS1. Additionally, the inspectors independently performed walkdowns of a sample of seismic protection features. The inspection report dated 9

ADAMS Accession No. ML12156A052

January 28, 2013, 10 documents the results of this inspection and states that no findings were identified.

4.0 INACCESSIBLE ITEMS The status of the limited number of inaccessible items and deferred cabinets is listed in of the September 16, 2013, letter. In that letter, the licensee committed to complete thewalkdown for the remaining inaccessible items and internal cabinet inspections by June 1, 2014, and submit the results of these walkdowns to the NRC by August 28, 2014.

5.0 CONCLUSION

The NRC staff concludes that the licensee's implementation of seismic walkdown methodology meets the intent of the walkdown guidance. The staff concludes that the licensee, through the implementation of the walkdown guidance activities and, in accordance with plant processes and procedures, verified the plant configuration with the current seismic licensing basis; addressed degraded, nonconforming, or unanalyzed seismic conditions; and verified the adequacy of monitoring and maintenance programs for protective features. Furthermore, the staff notes that no immediate safety concerns were identified. The staff acknowledges that a supplemental letter will be provided by August 28, 2014, addressing the remaining inaccessible iterrys consistent with the regulatory commitment. The NRC staff reviewed the information provided and determined that sufficient information was provided to be responsive to of the 50.54(f) letter.

10 ADAMS Accession No. ML13028A536

STAFF ASSESSMENT OF SEISMIC WALKDOWN REPORT NEAR-TERM TASK FORCE RECOMMENDATION 2.3 RELATED TO THE FUKUSHIMA DAI-ICHI NUCLEAR POWER PLANT ACCIDENT EXELON GENERATION COMPANY, LLC LASALLE COUNTY STATION. UNIT 2 DOCKET NO. 50-374

1.0 INTRODUCTION

On Marqh 12, 2012, 1 the U.S. Nuclear Regulatory Commission (NRC) issued a letter requesting information pursuant to Title 10 of the Code of Federal Regulations (1 0 CFR), Paragraph 50.54(f) (50.54(f) letter) to all power reactor licensees and holders of construction permits in active or deferred status. *The request was part of the implementation of lessons learned from the accident at the Fukushima Dai-ichi nuclear power plant. Enclosure 3, "Recommendation 2.3: Seismic," to the 50.54(f) letter requested licensees to conduct seismic walkdowns to identify and address degraded, nonconforming, or unanalyzed conditions using the corrective action program (CAP), verify the adequacy of monitoring and maintenal"}ce procedures,*and report the results to the NRC.

Enclosure 3 of the 50.54(f) letter requested licensees to provide the following:

a. Information concerning the plant-specific hazard licensing bases and a description of the protection and mitigation features considere:d in the licensing basis evaluation.

b. Information related to the implementation of the walkdown process.

c. A list of plant-specific vulnerabilities identified by the Individual Plant Examination of External Events (IPEEE) program and a description of the actions taken to eliminate

• or reduce them. '-

d. Results of the walkdown including key findings and identified degraded, nonconforming, or unanalyzed conditions.

e. Any planned or newly installed protection and mitigation features.

f. Results and any subsequent actions taken in response to the peer review.

In accordance with the 50.54(f) letter, Enclosure 3, Required Response Item 2, licensees were required to submit a response within 180 days of the NRC's endorsement of the seismic 1

Agencywide Document Access and M<jinagement System (ADAMS) Accession No. ML12053A340.

Enclosure 2

walkdown process. By letter dated May 29, 2012, 2 the Nuclear Energy Institute submitted Electric Power Research Institute document 1025286, "Seismic Walkdown Guidance for Resolution of Fukushima Near-Term Task Force Recommendation 2.3: Seismic," (walkdown guidance) to the NRC staff to consider for endorsement. By letter dated May 31, 2012, 3 the staff endorsed the walkdown guidance.

Byletter dated November 27, 2012, 4 as updated by letter dated June 19, 2013, 5 Exelon Generation Company, LLC (the licensee) provided a response to Enclosure 3 of the 50.54(f) letter, Required Response Item 2, for the LaSalle County Station, Unit 2 (LCS2). By letter dated September 16, 2013 6 , the licensee updated its commitment for completing and reporting the delayed inspections of remaining inaccessible items by August 28, 2014. The NRC staff reviewed the walkdown report and determined that additional supplemental information would assist the staff in completing its review. By letter dated November 1, 2013 7 , the staff requested additional information to gain a better understanding of the processes and procedures used by

• the licensee in conducting the walkdowns and walk-bys. The licensee responded to the staff -

request by letter dated November 27; 2013. 8 The NRC staff evaluated the licensee's submittals to determine if the information provided in the walkdown report met the intent of the walkdown guidance and if the licensee responded appropriately to Enclosure 3 of the 50.54(f) letter.

2.0 REGULATORY EVALUATION

The structures, systems, and components (SSCs) important to safety in operating nuclear power plants are designed either in accordance with, or meet the intent of Appendix A to 10 CFR Part 50, General Design Criteria (GDC) 2, "Design Bases for Protection Against Natural Phenomena," and Appendix A to 10 CFR Part 100, "Reactor Site Criteria.". GDC 2 states that SSCs important to safety at nuclear power plants shall be designed to withstand the effects of natural phenomena such as earthquakes, tornadoes, hurricanes, floods, tsunami, and seiches without loss of capability to perform their safety functions.

• For initial licensing, each licenseewas required to develop and maintain design bases that, as .

defined by 10 CFR 50.2, "Definitions," identify the specific functions that an SSC of a facility must perform, and the specific values or ranges of values chosen for controlling parameters as reference bounds for the design.

The design bases for the SSCs reflect appropriate consideration of the most severe natural phenomena that have been historically reported for the site and surrounding area. The design bases also reflect sufficient margin to account for the limited accuracy, quantity, and period of time in which the historical data have been accumulated.

2 ADAMS Package Accession No. ML121640872.

3 ADAMS Accession No. ML12145A529 ADAMS Package Accession No~ ML123530341 4

5 ADAMS Package Accession No. ML131920489 6

7 ADAMS Accession .No. ML13260A083 ADAMS Accession No: ML133048418 8

ADAMS Accession No. ML133318501

The current licensing basis is the set of NRC requirements applicable to a specific plant, including the licensee's docketed commitments for ensuring compliance with, and operation within, applicable NRC requirements and the plant-specific design basis, including all modifications and additions to such commitments over the life of the facility operating license.

3.0 TECHNICAL EVALUATION

3.1 Seismic Licensing Basis Information The licensee provided information on the plant-specific licensing basis for the Seismic Category I SSCs for LCS2 in Section 2.0 of the walkdown report. Consistent with the walkdown guidance, the NRC staff noted that the report includes a summary of the safe-shutdown earthquake (SSE) and a description of the codes, standards, and methods that were used in the design of the Seismic Category I SSCs for meeting the plant-specific seismic licensing basis requirements. The staff reviewed Section 2.0 of the walkdown report focusing on the summary of the SSE and the design codes used in the design.

Based on the NRC staff's review, the staff concludes that the licensee has provided information on the plant-specific seismic licensing basis and a description of the protection and mitigation features considered in the licensing bases evaluation consistent with Section 8, "Submittal Report," of the walkdown guidance.

3.2 Seismic Walkdown Methodology Implementation Section 2, "Personnel Qualifications"; Section 3, "Selection of SSCs"; Section 4, "Seismic Walkdowns and Area Walk-Bys"; and Section 5, "Seismic Licensing Basis Evaluations," of the walkdown guidance provide information to licensees regarding the implementation of an appropriate seismic walkdown methodology. By letter dated July 10, 2012, 9 the licensee confirmed that it would use the walkdown guidance to perform the seismic walkdowns at LCS2.

The walkdown reports dated November 27, 2012, and June 19, 2013, did not identify deviations from the walkdown guidance.

The NRC staff reviewed the following sections of the walkdown methodology implementation provided in the walkdown report: *

• Personnel Qualifications

• Development of the Seismic Walkdown Equipment Lists (SWELs)

• Implementation of the Walkdown Process

• Licensing Basis Evaluations and Results 3.2.1 Personnel Qualifications Section 2, "Personnel Qualifications," of the walkdown guidance provides licensees with qualification information for personnel involved in the conduct of the seismic walkdowns and area walk-bys.

9 ADAMS Accession No. ML12193A081.

6'

The NRC staff reviewed the information provided in Section 3 and Appendix A of the initial walkdown report, which includes information on the walkdown personnel and their qualifications.

Similarly, the staff reviewed Section 3A and Appendix AA of the updated walkdown report which contained information on new personnel' involved in the delayed walkdowns. The staff reviewed the summary of the background, experience, and level of involvement for the following personnel involved in the seismic walkdown activities: equipment selection personnel, seismic walkdown engineers (SWEs), licensing basis reviewers, IPEEE reviewers, peer review team, and operations staff.

Based on the review of the l.icensee's submittals, the NRC staff concludes that those involved in the seismic walkdown activities have the appropriate seismic background, knowledge and experience, as specified in Section 2 of the walkdown guidance.

3.2.2 Development of the SWELs Section' 3, "Selection of SSCs," of the walkdown guidance provides information to licensees for selecting the SSCs that should be placed on the SWELs, so that they can be walked down by qualified personnel.

The NRC staff reviewed the overall process used by the licensee to develop the LCS2 base list, SWEL 1 (sample list of designated safety functions equipment), and SWEL 2 (sample list of spent fuel pool (SFP)-related equipment). The licensee provided the base lists, SWEL 1 and SWEL 2 in Appendix B of the initial walkdown report and discussed these lists in Section 4.2 of the initial walkdown report. The licensee divided base list 1 into two parts-base list 1a for components exclusive to Unit 2, and base list 1b for components common to Units 1 and 2.

The overall equipment selection process followed the screening process shown in Figures 1-1 and 1-2 of the walkdown guidance. Based on Appendix B Tables B-3 and B-4 of the walkdown report, LCS2 SWELs 1 and 2 meet the inclusion requirements of the walkdown guidance.

• Specifically, the following attributes were considered in the sample selection:

• A variety of systems, equipment and environments

• IPEEE equipment *

• Major new or replacement equipment

• Risk considerations It is possible that some classes of equipment will not be represented on the SWEL due to individual plant configurations and the walkdown guidance screening process followed to select the final SWEL equipment. The walkdown guidance recognizes this is due to the equipment not being present in the plant (e.g., some plants generate direct current power using inverters and, therefore, do not have motor generators) or the equipment being screened out during the screening process (as described in Section 3 of the walkdown guidance). Based on the information provided, the NRC staff noted that a detailed explanation was provided justifying cases where specific classes of equipment were not included as part of the SWEL, and concludes that these exclusions are acceptable.

The NRC staff also noted that a rapid drain-down list was not included as part of the SWEL 2, as described in Section 3 of the guidance. In Section 4.2.2 of the updated walkdown report, the

licensee stated that there are no SFP penetrations below 10 feet above the top of the fuel assemblies. Based on this, the licensee concluded that there is no potential for rapid drain-down and, therefore, no items were added to SWEL 2. After reviewing the information provided in this section, the staff concludes that the licensee provided adequate justification for not*

including rapid drain-down items as part of the SWEL 2 for the LCS2 SFP.

After reviewing SWELs 1 and 2, the NRC staff concludes that the sample of SSCs represents a diversity of component types and assures inclusion of components from critical systems and functions, thereby, meeting the intent of the walkdown guidance. In addition, the NRC staff notes that the equipment selection personnel were appropriately supported by plant operations staff as described in the walkdown guidance.

3.2.3 Implementation of the Walkdown Process Section 4, "Seismic Walkdowns and Area*Walk-Bys," of the walkdown guidance provides information to licensees regarding the conduct of the seismic walkdown~ and area walk-bys for each site.

The NRC staff reviewed Section 5 of the updated walkdown report, which summarizes the results of the seismic walkdowns and area walk-bys, incluaing an overview of the number of items walked down and the number of areas walked-by. The updated walkdown report states that teams, which consisted of tvito qualified SWEs, conducted the seismicwalkdowns and area walk-bys. According to the signed seismic walkdown checklists (SWCs) and area walk-by checklists (AWCs), the initial walkdown activities were conducted in August and September 2012. Similarly, the delayed walkdown activities were conducted in February 2013.

The updated walkdown report states that the SWEs discussed their observations and judgments with each other during the walkdowns. Additionally, the SWEs agreed on the results of their seismic walkdowns and area vitalk-bys before reporting the results of their review. Appendices C and D of the initial walkdown report and Appendices AC and AD of the updated the walkdown report provide the completed SWCs and AWCs, documenting the results for each item of equipment on the SWELs 1 and 2 and each area containing SWEL equipment. The licensee used the checklists provided in Appendix C of the walkdown guidance report without modification.

The licensee documented cases of potentially adverse seismic conditions (PASCs) in the checklists for further evaluation. Tables A5-2 and A5-3 of the updated walkdown report list the PASCs identified during the seismic walkdowns and the area walk-bys. The tables describe how each condition was addressed (e.g., placement in the CAP), its resolution, and current status.

By letter dated November 1, 2013, the NRC staff issued two questions in a request for additional information (RAI) in order to obtain additional clarification regarding the process followed by the licensee when evaluating conditions identified in the field during the walkdowns and walk-bys. Specifically, in RAI 1, the staff requested the licensee to provide further .

explanation regarding how a field observation was determined to be a PASC, and to ensure that the basis for determination was addressed using normal plant processes and documented in the ~

walkdown report. In its November 27, 2013, response, the licensee confirmed that observations

which could not be readily judged to be acceptable with respect to its current licensing basis during the walkdown, and were not found to be previously evaluated as acceptable conditions

• through follow-up review of plant documentation, were identified as PASCs and were documented as issue reports in the LCS2 CAP. The licensee referred to Tables AS-2 and AS-"3 of the updated walkdown reports, which include conditions identified during the walkdowns and area walk-bys for LCS2. The licensee also stated that a conservative position regarding CAP entries was used to identify and document PASCs. The licensee stated that in addition to addressing the PASCs through the CAP, other nonseismic potentially adverse conditions, such as housekeeping and material conditions items, were identified by SWEs and addressed through the CAP. Furthermore, the licensee confirmed that, based on its review of the LCS2 walkdown process and the information submitted in the walkdown reports, that no new conditions were identified that required an additional supplement or additional CAP entries.

After evaluating the licensee's response and reviewing Tables AS-2 and AS-3 of the updated walkdown report, the NRC staff concludes that the licensee properly identified and documented the PASCs and that the summary tables provided are complete.

In addition to the information provided above, the NRC staff notes that anchorage configurations were verified to be consistent with existing plant documentation for at least 50 percent of t~e SWEL items, in accordance with Section 4 of the walkdown guidance.

Tables E-1 and E-2 of the initial walkdown report list the inaccessible components and cabinets that were not internally inspected during the initial walkdown activities. The licensee stated in Section A5.2 and Appendix AE of the updated walkdown that all inspections of inaccessible items identified in Table E-1 have been completed.

Regarding the internal inspections of cabinets, the licensee stated in Section A5.4 and Table AE-2 of the updated walkdown reports that the majority of the deferred inspections of inaccessible cabinets identified in Table E-2 of the initial walkdown report were internally inspected in February 2013. Accordingly, Table AE-2 confirms that only a small number of cabinet inspections (five total) have not been completed. In Attachment 5 of the September 16, 2013, letter, the licensee provided a revised list of all remaining internal cabinet inspections.

The NRC staff noted that one cabinet of the remaining five will not be available for internal inspection due to the extensive disassembly required. The staff concludes that the exclusion of this single piece of equipment is acceptable and maintains the diversity of the equipment classes in the original SWEL.

In its September 16, 2013, letter, the licensee committed to complete the walkdowns for the limited number of remaining inaccessible items (i.e., cabinets) by June 1, 2014, and submit the final walkdown report to the NRC by August 28, 2014. The NRC staff concludes that the inaccessible equipment list was developed consistent with the walkdown guidance. The schedule for completion is consistent with the timing of the next scheduled refueling and system outages.

Based on the information provided in the licensee's submittals, the NRC staff concludes that the licensee's implementation of the walkdown process meets the intent of the walkdown guidance.

3.2.4 Licensing Basis Evaluations and Results Section 5, "Seismic Licensing Basis Evaluations," of the walkdown guidance provides information to licensees regarding the conduct of licensing basis evaluations for items identified during the seismic walkdowns as degraded, nonconforming, or unanalyzed that might have potential seismic significance.

The NRC staff reviewed Section *6 of the walkdown report, which discusses the process for conducting the seismic licensing basis evaluations of the PASCs identified during the seismic walkdowns and area walk-bys. The licensee stated that all questionable conditions identified during the walkdown were entered into the CAP. Tables A5-2 and A5-3 of the updated walkdown report list the key licensee findings, and provide a complete list of the potentially degraded, nonconforming, or unanalyzed, conditions. These tables also describe the actions taken or planned to address these conditions, including the current status of each of the items the licensee entered into the CAP.

The NRC staff reviewed the CAP entries and the description of the actions taken or planned to address potential deficiencies. The staff concludes that the licensee appropriately identified degraded, nonconforming, or unanalyzed conditions and entered them into the CAP, which meets the intent of the walkdown guidance.

3.2.5 Conclusion Based on the discussion above, the NRC staff concludes that the licensee's implementation of seismic walkdown methodology meets the intent of the walkdown guidance for personnel qualifications, development of SWELs, implementation of the walkdown process, and seismic licensing basis evaluations.

3.3 Peer Review Section 6, "Peer Review," of the walkdown guidance provides licensees with information regarding the conduct of peer reviews for the activities performed during the seismic walkdowns. Page 6-1 of the walkdown guidance identifies the following activities to be conducted during the peer review process:

• Review the selection of the SSCs included on the SWELs.

• Review a sample of the checklists prepared for the seismic walkdowns and area walk-bys.

• Review the licensing basis evaluations.

• Review the decisions for entering the potentially adverse conditions into the CAP.

• Review the walkdown report.

• Summarize the results of the peer review process in the walkdown report.

The NRC staff reviewed the information provided in Section 8 and Appendix F of the walkdown report, and the November 27, 2013, letter, which describe the conduct of the peer review. In RAI 2, the staff requested the licensee to provide additional information on the overall peer

review process that was followed as part of the walkdown activities. Specifically, the staff requested the licensee to confirm that the activities identified on page 6-1 of the walkdown guidance were assessed and documented in the report. The licensee was also requested to confirm that any individual involved in performing any given walkdown activity was not a peer reviewer for that same activity. In its November 27, 2013, letter, the licensee confirmed that all the activities identified on page 6-1 of the walkdown guidance were included as part of the peer review process and referred to the summary of the peer review activities provided in Appendix F of the walkdown report. In addition, the licensee stated that there were no cases where any peer reviewer reviewed their own work.

The NRC staff reviewed the licensee's summary of each of these activities, which included a discussion of the peer review team members' qualifications and level of involvement, the peer review findings, and resolution of peer review comments. After reviewing the licensee's submittals, the NRC staff concludes that the licensee sufficiently documented the results of the peer review activities and how these reviews affected the work described in the walkdown report.

Based on the discussion above, the NRC staff concludes that the licensee's results of the peer review and subsequent action*s taken in response to the peer review meets the intent of Section 6 of the walkdown guidance.

3.4 IPEEE Information Section 7, "IPEEE Vulnerabilities," of the walkdown guidance provides information to licensees regarding the reporting of the evaluations conducted and actions taken in response to seismic vulnerabilities identified during the IPEEE program. Through the IPEEE program and Generic Letter 88-20, "Individual Plant Examination of External Events for Severe Accident Vulnerabilities," licensees previously performed a systematic examination to identify any plant-specific vulnerabilities to severe accidents.

The licensee provided background information regarding its IPEEE program and referenced several submittals to the NRC. The licensee stated in Section 7 of the walkdown report that "a review of the LaSalle County Nuclear Power Station [IPEEE] Submittal along with the NRC Staff Evaluation Report of the IPEEE found that no vulnerabilities were identified and no plant improvements resulted from the IPEEE program."

Based on the NRC staff's review of Section 7 of the walkdown report, the staff concludes that the licensee's summary of the IPEEE is consistent with and meets the intent of Section 7 of the walkdown guidance.

3.5 Planned Upgrades The licensee did not identify any planned or newly installed protection and mitigation features in the walkdown report.

• 3.6 NRC Oversight 3.6.1 Independent Verification *by Resident Inspectors On July 6, 2012, 10 the NRC issued Temporary Instruction (TI) 2515/188 "Inspection of Near-Term TaskForce Recommendation 2.3 Seismic Walkdowns." In accordance with the Tl, NRC inspectors independently verified that the licensee implemented the seismic walkdowns in accordance with the walkdown guidance. Additionally, the inspectors independently performed walkdowns of a sample of seismic protection features. The inspection report dated January 28, 2013, 11 documents the results of this inspection and states that no findings were identified.

4.0 INACCESSIBLE ITEMS The status of the limited number of deferred cabinets is listed in Attachment 5 of the September 16, 2013 letter. In that letter, the licensee committed to complete the walkdown for the remaining inaccessible items and internal cabinet inspections by June 1, 2014, and submit the results of these walkdowns to the NRC by August 28, 2014.

5.0 CONCLUSION

The NRC staff concludes that the licensee's implementation of seismic walkdown methodology meets the intent of the walkdown guidance. The staff concludes that the licensee, through the implementation of the walkdown guidance activities and, in accordance with plant processes and procedures, verified the plant configuration with the current seismic licensing basis; addressed degraded, nonconforming, or unanalyzed seismic conditions; and verified the adequacy of monitoring and maintenance programs for protective features. Furthermore, the staff notes that no immediate safety concerns were identified. The staff acknowledges that a supplemental letter will be provided by August 28, 2014, addressing the remaining inaccessible items consistent with the regulatory commitment. The staff reviewed the information provided and determined that sufficient information was provided to be responsive to Enclosure 3 of the 50.54(f) letter.

10 ADAMS Accession No. ML12156A052 11 ADAMS Accession No. ML13028A536

M. Pacilio If you have any questions, please contact me at 301-415-1380 or by e-mail at Blake.Purnell@nrc.gov.

Sincerely, IRA/

Blake Purnell, Project Manager Plant Licensing 111:-2 and Planning and Analysis Branch Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-373 and 50-37 4

Enclosures:

1. Staff Assessment of Seismic Walkdown Report for Unit 1

2. Staff Assessment of Seismic Walkdown Report for Unit 2 cc w/encl: Distribution via Listserv DISTRIBUTION:

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