ML14086A624

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 (MF0157 and MF0158)

ML14086A624
Person / Time
Site:	Peach Bottom
Issue date:	04/30/2014
From:	Richard Ennis Plant Licensing Branch 1
To:	Pacilio M Exelon Nuclear
Ennis R, NRR/DORL/LPLI-2
References
TAC MF0166, TAC MF0167
Download: ML14086A624 (22)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Mr. Michael J. Pacilio President and Chief Nuclear Office Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555 April 30, 2014

SUBJECT:

PEACH BOTTOM ATOMIC POWER STATION, UNITS 2 AND 3-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. MF0157 AND MF0158)

Dear Mr. Pacilio:

On March 12, 2012, the U.S. Nuclear Regulatory Commission (NRC) issued a request for information letter per Title 10 of the Code of Federal Regulations, Subpart 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 further 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 maintenance procedures.

By letter dated November 19, 2012, Exelon Generation Company (Exelon) submitted its Seismic Walkdown Report as requested in Enclosure 3 of the 50.54(f) letter for the Peach Bottom Atomic Power Station, Units 2 and 3 (PBAPS-2 and PBAPS-3).

By letter dated September 16, 2013, Exelon provided additional information on the completion of inaccessible items in order to complete all walkdowns and submit the final walkdown report.

By letter dated November 27, 2013, Exelon provided a response to the request for additional information for the NRC staff to complete its assessments. By letter dated March 25, 2014, Exelon provided an updated walkdown report for PBAPS-3. The NRC staff acknowledges that a supplemental letter will be provided by December 31, 2014, addressing the remaining inaccessible items consistent with the regulatory commitment for PBAPS-2.

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. This concludes the NRC staff's efforts associated with TAC Nos. MF0157 and MF0158.

If you have any questions, please contact me at 301-415-1420 or by e-mail at Rick. Ennis@nrc.gov.

Docket Nos. 50-277 and 50-278

Enclosures:

1. Staff Assessment of Seismic Walkdown Report for PBAPS-2

2. Staff Assessment of Seismic Walkdown Report for PBAPS-3 cc w/encls: Distribution via Listserv Sincerely, Richard B. Ennis, Senior Project Manager Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

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 PEACH BOTTOM NUCLEAR POWER STATION. UNIT 2 DOCKET NO. 50-277

1.0 INTRODUCTION

On March 12, 2012, 1 the U.S. Nuclear Regulatory Commission (NRC) issued a request for information per Title 10 of the Code of Federal Regulations, Subpart 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., "Recommendation 2.3: Seismic,"2 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. 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 vulnerabilities... identified by the IPEEE [Individual Plant Examination of External Events] 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 Documents Access and Management System (ADAMS) Accession No. ML12053A340.

2 ADAMS Accession No. ML12056A049.

walkdown process. By letter dated May 29, 2012, 3 the Nuclear Energy Institute (NEI) staff submitted Electric Power Research Institute (EPRI) 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, 2012,4 the NRC staff endorsed the walkdown guidance.

By letter dated November 19, 2012,5 Exelon Generation Company (the licensee) provided a response to Enclosure 3 of the 50.54(f) letter Required Response Item 2, for Peach Bottom Atomic Power Station, Unit 2 (PBAPS-2). 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, 2013,6 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 for Nuclear Power Plants," Criterion 2: "Design bases for protection against natural phenomena;" and Appendix A to 10 CFR Part 100, "Reactor Site Criteria." Criterion 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, 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.

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, 3 ADAMS Package Accession No. ML121640872.

4 ADAMS Accession No. ML12145A529.

5 ADAMS Package Accession No. ML130030017.

6 ADAMS Accession No. ML133048418.

7 ADAMS Accession No. ML133318501.

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 PBAPS-2 in Section 2, Seismic Licensing Basis, 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 NRC staff reviewed Section 2 of the walkdown report, focusing on the summary of the SSE and the design codes used in the design.

Based on its review, the NRC 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 (EPRI Document 1 025286) provides 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 in the performance of the seismic walkdowns at PBAPS-2.

The walkdown report dated November 19, 2012, did not identify deviations from the walkdown guidance. The NRC staff reviewed the procedure and methodology and concludes that the walkdown report meets the intent of 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 8 ADAMS Accession No. ML12193A081.

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.

The NRC staff reviewed the information provided in Section 3, Personnel Qualifications, and Appendix A, Project Personnel Resumes and SWE [seismic walkdown engineer) Certificates, 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, SWEs, licensing basis reviewers, IPEEE reviewers, peer review team, and operations staff.

The NRC staff noted that the walkdown report did not clearly describe the role of the operations staff beyond the selection of the SWEL items. In its response to request for additional information (RAI) 1 (described below), the licensee clarified that operations personnel reviewed the final SWEL and were involved in the walkdowns when potential operability issues were noted by the SWEs.

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 PBAPS-2 base list, SWEL 1 (sample list of designated safety functions equipment), and SWEL 2 (sample list of spent fuel pool related equipment). The licensee stated that due to plant configuration, some of the Base-1 components are common to both Peach Bottom units, PBAPS-2 and PBAPS-3.

Therefore, the licensee created a SWEL 1 for Unit 2 (PBAPS-2 specific items) and another SWEL 1 for Unit 0 (common equipment for PBAPS-2 and 3).

Regarding SWEL 2, the licensee stated that no spent fuel pool related Seismic Class 1 equipment for PBAPS-2 were identified, including rapid drain-down items or components (as discussed below), hence, no components are included in the PBAPS-2 SWEL 2.

The licensee provided the base list, SWEL 1 for Unit 2 and SWEL 1 for Unit 0 (common items) in Appendix B, Equipment Lists, of the walkdown report and discussed these lists in Section 4.2, SWEL 1 - Sample of Required Items for the Five Safety Functions, of the walkdown report. As previously stated, the SWEL 2 list is not provided, as it contains no components. Consequently, the licensee explained that the final SWEL for PBAPS-2 only consists of the combined SWEL 1, since there are no SWEL 2 items.

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 of the walkdown report, PBAPS-2 SWEL meets 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 Due to individual plant configurations and the walkdown guidance screening process followed to select the final SWEL equipment, it is possible that some classes of equipment will not be represented on the SWEL. 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 (the screening process is 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.

As previously described, the licensee did not include SWEL 2 items in the final SWEL. In addition, 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, Screen #2-Equipment or Systems, of the walkdown report, the licensee stated there are no components that could, upon failure, result in rapid drain-down of the spent fuel pool water level to below 3 meters (1 0 feet) above the top of the fuel. After reviewing the information provided in this section, the NRC staff concludes that the licensee provided adequate justification for not including rapid drain-down items as part of the SWEL.

After reviewing the SWEL, the NRC staff concludes that the sample of SSCs represents 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 walkdowns and area walk-bys for each site.

The NRC staff reviewed Section 5, Seismic Walkdowns and Area Walk-Bys, 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 at least 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 over the course of 3 months from August 2012 to October 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, Area Walk-By Checklists, of the walkdown report provide the completed SWCs and AWCs, documenting the results for each item of equipment on the SWELs 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. The licensee stated that none of the issues identified during the walkdowns were ultimately judged to be PASCs. Tables 5-2 and 5-3 of the walkdown report list the conditions 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. Based on the initial review of the checklists, the NRC staff was unable to confirm that all the PASCs identified during the walkdowns were included in this table.

By letter dated November 1, 2013, the NRC staff issued two questions in an 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 NRC 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 response to RAI 1, the licensee confirmed that all conditions identified during the walkdowns and walk-bys were documented as issue reports (IRs) in the PBAPS-2 CAP. The licensee referred to Tables 5-2 and 5-3 of the walkdown report, which include all the conditions identified during the walkdowns and area walk-bys for PBAPS-2, as well as other potentially adverse conditions. As described previously, the licensee stated that all conditions identified in PBAPS-2 were ultimately judged to not be PASCs.

Nevertheless, the licensee stated that all identified non-seismic 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 PBAPS-2 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, the NRC staff concludes that the licensee responded appropriately to RAI 1, conditions, including any PASC, were properly identified and documented, and summary Tables 5-2 and 5-3 are considered 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, E-2, and E-3 list equipment and areas that were inaccessible during the 180-day period. Table E-1 lists one (1) SWEL component that was inaccessible at the time of the walkdowns, its respective completion date, and status. By letter dated March 25, 2014, 9 the 9 ADAMS Accession No. ML14091A479.

licensee provided an updated walkdown report for PBAPS-2.

In the aforementioned letter, the licensee stated that the walkdown for the one inaccessible component was able to be completed during the PBAPS-2 delayed walkdown activities. The licensee stated that no new adverse seismic condition was identified as a result of the new walkdown.

Tables E-2 and E-3 list a total of three (3) deferred walkdowns of cabinets that were not internally inspected. Attachments 7 and 12, presented in the letter dated September 16, 2013, 10 provide the status and an updated list of deferred cabinets with their expected date of completion. The next refueling outage for PBAPS-2 is in the 41h quarter of 2014. The licensee committed to complete all walkdowns for the deferred cabinets by September 30, 2014, and submit the final walkdown report to the NRC by December 31, 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, Licensing Basis Evaluations, of the PBAPS-2 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 since all conditions identified during the walkdowns and walk-bys were not determined to be PASCs, no formal licensing basis evaluations were necessary nor performed. The licensee added that in all cases, the identified conditions would not prevent the equipment or component from performing its safety-related function. Tables 5-2 and 5-3 of the 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.

10 ADAMS Accession No. ML13260A083.

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, Peer Review, of the PBAPS-2 walkdown report, which describes the conduct of the peer review.

In addition, the staff reviewed the response to RAI 2.

In RAI 2, the NRC 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 response to RAI 2, 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 Section 8 and the full peer review report in Appendix F, Peer Review Report, of the walkdown report. In addition, the licensee stated that there were "no cases where any peer reviewer reviewed their own work for the EGC [Exelon Generation Company] fleet."

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 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 for Severe Accident Vulnerabilities-10 CFR 50.54(f)," dated November 23, 1988, 11 licensees previously had performed a systematic examination to identify any plant-specific vulnerabilities to severe accidents.

The licensee provided background information regarding their IPEEE program and referenced several submittals to the NRC. The licensee stated that identified and outstanding vulnerabilities reported in previous reports have been resolved. The licensee lists, in Tables 7-1 and 7-2 of the walkdown report, previously identified vulnerabilities, their resolution status and indicates which of them were verified in the field during the current seismic walkdown activities.

Based on its review of Section 7, IPEEE Vulnerabilities Resolution Report, of the walkdown report, the NRC 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, 12 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 PBAPS 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 29, 2013, 13 documents the results of this inspection. No findings were identified.

4.0 INACCESSIBLE ITEMS The status of the deferred inspections for the limited number of cabinets is listed in Attachment 7 of the September 16, 2013, letter.

The walkdown results for the remaining internal cabinet inspections were committed to be completed by September 30, 2014. The licensee committed to provide a final walkdown report with the results by December 31, 2014.

11 ADAMS Accession No. ML031150465.

12 ADAMS Accession No. ML12156A052.

13 ADAMS Accession No. ML13029A013.

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, through the implementation of the walkdown guidance activities and, in accordance with plant processes and procedures, the licensee 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 December 31, 2014, addressing the remaining inaccessible items 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, dated March 12, 2012.

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 PEACH BOTTOM NUCLEAR POWER STATION, UNIT 3 DOCKET NO. 50-278

1.0 INTRODUCTION

On March 12, 2012, 1 the U.S. Nuclear Regulatory Commission (NRC) issued a request for information per Title 10 of the Code of Federal Regulations, Subpart 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., "Recommendation 2.3: Seismic,"2 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. 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 vulnerabilities... identified by the IPEEE [Individual Plant Examination of External Events] 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 Documents Access and Management System (ADAMS) Accession No. ML12053A340.

2 ADAMS Accession No. ML12056A049.

walkdown process. By letter dated May 29, 2012, 3 the Nuclear Energy Institute (NEI) staff submitted Electric Power Research Institute (EPRI) 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, 2012,4 the NRC staff endorsed the walkdown guidance.

By letter dated November 19, 2012, 5 Exelon Generation Company (the licensee) provided a response to Enclosure 3 of the 50.54(f) letter Required Response Item 2, for Peach Bottom Atomic Power Station, Unit 3 (PBAPS-3). The NRC staff reviewed the walkdown report and determined that additional supplemental information would assist the staff in completing its review.

In 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 By letter dated March 25, 2014, 8 the licensee provided an updated submittal to the initial seismic walkdown report for PBAPS-3. The purpose of the latter submittal was to update the initial walkdown report with information and results on the delayed walkdowns and walk-bys of inaccessible structures, systems, and components (SSCs), which were not completed in the first submittal.

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 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 for Nuclear Power Plants," Criterion 2: "Design bases for protection against natural phenomena;" and Appendix A to 10 CFR Part 100, "Reactor Site Criteria." Criterion 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, identify the specific functions that an sse 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.

3 ADAMS Package Accession No. ML121640872.

4 ADAMS Accession No. ML12145A529.

5 ADAMS Package Accession No. ML130030017.

6 ADAMS Accession No. ML133048418.

7 ADAMS Accession No. ML133318501.

8 ADAMS Package Accession No. ML14091A468.

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 PBAPS-3 in Section 2, Seismic Licensing Basis, of the initial 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 NRC staff reviewed Section 2 of the walkdown report, focusing on the summary of the SSE and the design codes used in the design.

Based on its review, the NRC 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 walk down guidance (EPRI Document 1 025286) provides 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 in the performance of the seismic walkdowns at PBAPS-3.

The walkdown reports dated November 19, 2012, and March 25, 2014, did not identify deviations from the walkdown guidance. The NRC staff reviewed the procedure and methodology and concludes that the walkdown report meets the intent of the walkdown guidance.

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

Personnel Qualifications Development of the Seismic Walkdown Equipment Lists (SWELs)

Implementation of the Walkdown Process Licensing Basis Evaluations and Results 9 ADAMS Accession No. ML12193A081.

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.

The NRC staff reviewed the information provided in Section 3, Personnel Qualifications, and Appendix A, Project Personnel Resumes and SWE [seismic walkdown engineer] Certificates, of the initial walkdown report, which includes information on the walkdown personnel and their qualifications. Similarly, the staff reviewed Section A3, Personnel Qualifications, and Appendix AA, Project Personnel Resumes and SWE Certificates, of the updated walkdown report, which includes information on personnel involved in the supplemental walkdowns.

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, SWEs, licensing basis reviewers, IPEEE reviewers, peer review team, and operations staff.

The NRC staff noted that the walkdown report did not clearly describe the role of the operations staff beyond the selection of the SWEL items.

In its response to request for additional information (RAI) 1 (described below), the licensee clarified that operations personnel reviewed the final SWEL and were involved in the walkdowns when potential operability issues were noted by the SWEs.

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 PBAPS-3 base list, SWEL 1 (sample list of designated safety functions equipment), and SWEL 2 (sample list of spent fuel pool related equipment). The licensee stated that due to plant configuration, some of the Base-1 components are common to both Peach Bottom units, PBAPS-2 and PBAPS-3.

Therefore, the licensee created a SWEL 1 for Unit 3 (PBAPS-3 specific items) and another SWEL 1 for Unit 0 (common equipment for PBAPS-2 and 3).

Regarding SWEL 2, the licensee stated that no spent fuel pool related Seismic Class 1 equipment for PBAPS-3 were identified, including rapid drain-down items or components (as discussed below), hence, no components are included in the PBAPS-3 SWEL 2.

The licensee provided the base list, SWEL 1 for Unit 3 and SWEL 1 for Unit 0 (common items) in Appendix B, Equipment Lists, of the walkdown report and discussed these lists in Section 4.2, SWEL 1 -Sample of Required Items for the Five Safety Functions, of the walkdown report. As previously stated, the SWEL 2 list is not provided, as it contains no components. Consequently, the licensee explained that the final SWEL for PBAPS-3 only consists of the combined SWEL 1 since there are no SWEL 2 items.

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 of the walkdown report, PBAPS-3 SWEL meets 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 Due to individual plant configurations and the walkdown guidance screening process followed to select the final SWEL equipment, it is possible that some classes of equipment will not be represented on the SWEL. 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 (the screening process is 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.

As previously described, the licensee did not include SWEL 2 items in the final SWEL.

In addition, 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, Screen #2-Equipment or Systems, of the walkdown report, the licensee stated there are no components that could, upon failure, result in rapid drain-down of the spent fuel pool water level to below 3 meter (1 0 feet) above the top of the fuel. After reviewing the information provided in this section, the NRC staff concludes that the licensee provided adequate justification for not including rapid drain-down items as part of the SWEL.

After reviewing the SWEL, the NRC staff concludes that the sample of SSCs represents 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 walkdowns and area walk-bys for each site.

The NRC staff reviewed Section 5, Seismic Walkdowns and Area Walk-Bys, 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 at least two qualified SWEs conducted the seismic walkdowns and area walk-bys. According to the signed seismic walkdown checklists (SWCs) and area walk-bys checklists (AWCs), the initial walkdown activities were conducted over the course of 3 months from August, 2012 to October, 2012. Similarly, the delayed walkdown activities were conducted intermittently during the months of March, May, June, September, and October of 2013.

The updated 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; and AC, Seismic Walkdown Checklists (SWC's),

and AD, Area Walk-By Checklists (AWC's), of the updated walkdown report provide the completed SWCs and AWCs, documenting the results for each item of equipment on the SWELs and each area containing SWEL equipment provide the completed SWCs and AWCs, documenting the results for each item of equipment on the SWELs 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. The licensee stated that none of the issues identified during the walkdowns were ultimately judged to be PASCs. Tables A5-2 and A5-3 of the updated walkdown report list the conditions identified during both seismic walkdowns and area walk-bys. The tables describe how each condition was addressed (e.g., placement in the CAP), its resolution and current status.

Based on the initial review of the checklists, the NRC staff was unable to confirm that all the PASCs identified during the walkdowns were included in this table.

By letter dated November 1, 2013, the NRC staff issued two questions in an 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 NRC 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 response to RAI 1, the licensee confirmed that all conditions identified during the walkdowns and walk-bys were documented as issue reports (IRs) in the PBAPS-3 CAP.

The licensee referred to Tables 5-2 and 5-3 of the walkdown report, which include all the conditions identified during the walkdowns and area walk-bys for PBAPS-3, as well as other potentially adverse conditions. As described previously, the licensee stated that all conditions identified in PBAPS-3 were ultimately judged to not be PASCs.

Nevertheless, the licensee stated that all non-seismic 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 PBAPS-3 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 A5-2 and A5-3, the NRC staff concludes that the licensee responded appropriately to RAI 1. In addition, the NRC staff concludes that conditions, including any PASCs, were properly identified and documented, and the summary tables provided are considered 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, E-2, and E-3 of the initial walkdown report, list equipment and areas that were inaccessible during the 180-day period. Table E-1 lists thirteen (13) SWEL components that were inaccessible at the time of the initial walkdowns. Similarly, Tables E-2 and E-3 of the initial walkdown report list a total of six (6) deferred walkdowns of cabinets that were not internally inspected. The licensee stated in Section A5.2, Seismic Walkdowns, of the updated walkdown report, that all walkdowns of remaining SWEL items and internal inspections of cabinets were completed. The licensee documented the results of these walkdowns, walk-bys and inspections in Appendices AC and AD of the updated walkdown report. The licensee stated that no new adverse seismic condition was identified as a result of these new walkdowns.

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, Licensing Basis Evaluations, of the PBAPS-3 initial and updated walkdown reports, which discuss 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 since all conditions identified during the walkdowns and walk-bys were not determined to be PASCs, no formal licensing basis evaluations were necessary nor performed.

The licensee added that in all cases, the identified conditions would not prevent the equipment or component from performing its safety-related function. 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 NRC 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, Peer Review, of the PBAPS-3 walkdown report, which describes the conduct of the peer review.

In addition, the NRC staff reviewed the response to RAI 2.

In RAI 2, the NRC 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 NRC 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 response to RAI 2, 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. The licensee referred to the summary of the peer review activities provided in Section 8, and the full peer review report in Appendix F, Peer Review Report, of the initial walkdown report. In addition, the licensee stated that there were "no cases where any peer reviewer reviewed their own work for the EGC fleet." In Section A8, Peer Review, of the updated walkdown report, the licensee re-affirmed that peer reviews for the delayed walkdowns were performed independently and referred to the full peer report of delayed walkdowns in Appendix AF, Peer Review Report.

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 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 for Severe Accident Vulnerabilities-10 CFR 50.54(f)," dated November 23, 1988,"10 licensees previously had 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 that identified and outstanding vulnerabilities reported in previous reports have been resolved. The licensee lists, in Tables 7-1 and 7-2 of the initial walkdown report, previously identified vulnerabilities, their resolution status, and indicates which of them were verified in the field during the current seismic walkdown activities.

Based on its review of Section 7, IPEEE Vulnerabilities Resolution Report, of the walkdown report, the NRC 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, 11 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 PBAPS 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 29, 2013, 12 documents the results of this inspection. No findings were identified.

4.0 CONCLUSION

The NRC staff concludes that the licensee's implementation of seismic walkdown methodology meets the intent of the walkdown guidance. The NRC staff concludes that, through the implementation of the walkdown guidance activities and, in accordance with plant processes and procedures, the licensee 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 NRC staff notes that no immediate safety concerns were identified. The NRC staff concludes that the licensee responded appropriately to Enclosure 3 of the 50.54(f) letter, dated March 12, 2012.

10 ADAMS Accession No. ML031150465.

11 ADAMS Accession No. ML12156A052.

12 ADAMS Accession No. ML13029A013.

If you have any questions, please contact me at 301-415-1420 or by e-mail at Rick. Ennis@nrc.gov.

Sincerely, IRA/

Richard B. Ennis, Senior Project Manager Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-277 and 50-278

Enclosures:

1. Staff Assessment of Seismic Walkdown Report for PBAPS-2

2. Staff Assessment of Seismic Walkdown Report for PBAPS-3 cc w/encls: Distribution via Listserv DISTRIBUTION:

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