ML14043A476

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

ML14043A476
Person / Time
Site:	Vogtle
Issue date:	02/24/2014
From:	Martin R Plant Licensing Branch II
To:	Pierce C Southern Nuclear Operating Co
Martin, Robert NRR/DORL 415-1493
References
TAC MF0190
Download: ML14043A476 (12)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 February 24, 2014 Mr. C. R. Pierce Regulatory Affairs Director Southern Nuclear Operating Company, Inc.

Post Office Box 1295, Bin- 038 Birmingham, AL 35201-1295

SUBJECT:

VOGTLE ELECTRIC GENERATING PLANT, UNIT 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 NO. MF0190)

Dear Mr. Pierce:

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 27, 2012, as supplemented by letter dated July 25, 2013, Southern Nuclear Operating Company (SNC) submitted its Seismic Walkdown Report as requested in of the 50.54(f) letter for the Vogtle Electric Generating Plant, Unit 2. By letter dated November 25, 2013, SNC provided a response to the NRC request for additional information for the staff to complete its assessments.

C. R. Pierce The NRC staff reviewed the information provided and, as documented in the enclosed staff assessment, determined that sufficient information was provided to be responsive to Enclosure 3 of the 50.54(f) letter. This concludes the NRC's efforts associated with TAC No. MF0190.

Sincerely,

~fa~!

Plant Licensing Branch 11-1 Manager Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-425

Enclosure:

Staff Assessment of Seismic Walkdown Report 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 SOUTHER NUCLEAR OPERATING COMPANY VOGTLE ELECTRIC GENERATING PLANT, UNIT 2 DOCKET NO. 50-425

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. Enclosure 3, "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 Individual Plant Examination of External Events (I PEE E) 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.

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

ADAMS Accession No. ML12056A049 Enclosure

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 walkdown process. By letter dated May 29, 2012, 1 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, 2 the NRC staff endorsed the walkdown guidance.

By letter dated November 27, 2012, 3 Southern Nuclear Operating Company (the licensee) provided a response to Enclosure 3 of the 50.54(f) letter Required Response Item 2, for Vogtle Electric Generating Plant, Unit 2 (VEGP-2). In addition to the aforementioned letter, the licensee, by letter dated July 25, 20134 , provided an updated submittal to the initial seismic walkdown report. The purpose of the latter submittal was to update and provide information on inaccessible components not completed in the first submittal The NRC staff reviewed the walkdown report and determined that additional supplemental information would assist the NRC staff in completing its review. In letter dated November 1, 2013 5 , 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 25, 2013. 6 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, 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.

1 ADAMS Package Accession No. ML121640872 2

ADAMS Accession No. ML12145A529 3

ADAMS Accession No. ML12555A033 4

ADAMS Accession No. ML13211A256 5

ADAMS Accession No. ML133048418 6

ADAMS Accession No. ML13330A531

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, 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 VEGP-2 in Section 3.0 of the walkdown reports. Consistent with the walkdown guidance, the NRC staff noted that the report includes a summary of the Safe Shutdown Earthquake (SSE), Operating Basis Earthquake (OBE) 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.

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 provide information to licensees regarding the implementation of an appropriate seismic walkdown methodology. By letter dated July 18, 2012, 7 the licensee confirmed that it would utilize the walkdown guidance in the performance of the seismic walkdowns at VEGP-2.

The walkdown reports dated November 27, 2012 and July 25, 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 7

ADAMS Accession No. ML12192A513

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 4 of the updated walkdown report, which includes information on the walkdown personnel and their qualifications. Specifically, the NRC 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 VEGP-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 the safe shutdown equipment list (SSEL) developed for the Vogtle Nuclear Plant IPEEE Unit 2 was used as the source for Base 1. The NRC staff notes that the SSEL list, which addresses SSCs associated with the reactor safe shutdown functions and as approved by the walkdown guidance, is a valid starting point to develop the plant's base list and SWEL 1.

The overall equipment selection process followed the screening process shown in Figures 1-1 and 1-2 of the walkdown guidance. Based on Attachment 1 of the walkdown report, VEGP-2 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 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 DC 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.

The NRC staff noted that no rapid drain down items were included as part of the SWEL 2, as described in Section 3 of the guidance. In Section 6.2 of the walkdown report, the licensee stated that all piping terminates or has anti-siphon holes ten feet above the fuel; therefore, there are no components that could, upon failure, result in rapid drain-down of the spent fuel pool (SFP) water level to below ten feet above the top of the fuel. After reviewing the information provided in this section, the NRC staff concludes that the licensee provided sufficient information to justify that there are no items which could lead to rapid drain-down of the VEGP-2 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 walkdowns and area walk-bys for each site.

The NRC staff reviewed Section 7 of the updated 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 walkdown checklists (AWCs), the activities for the initial walkdowns were conducted from August 13, 2012 to September 12,2012. The delayed walkdowns were performed in the 2R16 outage during the spring of 2013. The licensee stated that during the delayed walkdowns of all 28 cabinets that needed additional internal inspections and all 11 inaccessible items, respectively identified in Tables 7-1 and 7-2 of the initial report, were inspected.

The walkdown report does not explicity state that the SWEs discussed their observations and judgments with each other during the walkdowns. Based on a detailed review of the signed checklists and the walkdown report, the NRC staff notes that it is apparent that such interactions took place and that the SWEs agreed on the results of their seismic walkdowns and area walk-bys before reporting the results of their review. Attachments 3 and 4 of the walkdown report provide the completed SWCs and AWCs, documenting the results for each item of equipment on SWEL 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. Table 8-1 of the walkdown report list the PASCs identified during the seismic walkdowns and the area walk-bys. The table describes how each condition was addressed (e.g., placement in the CAP), its resolution and its current status. Based on the

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 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 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 cites Section 7 of the updated walkdown report and it stated that when a PASC was identified during a walkdown, it was noted on the SWC or the AWC, as applicable and a condition report (CR) was generated to document the finding. In addition, the licensee refers to Section 8, specifically Table 8.1, of the updated walkdown report which includes all PASCs identified and their status. The licensee added that it has a very low threshold for CAs and, therefore all PASCs identified were "conservatively entered into the Plant's CAP per Southern Nuclear expectations in a timely fashion".

After evaluating the licensee's response and reviewing Table 8-1, the NRC staff concludes that the licensee responded appropriately to RAI 1, PASCs were properly identified and documented and summary Table 8-1 is 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.

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 8 of the updated VEGP-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 it performed its licensing basis evaluations and resolved PASCs using the CAP. Table 8-1 of the walkdown report lists the key licensee findings, and provides a complete list of the potentially degraded, nonconforming, or unanalyzed conditions. This table also describes a summary of the condition, brief discussion of the analysis, and 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 deficiencies. The NRC staff concludes that the licensee appropriately identified potentially 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 9 of the updated VEGP-2 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 in 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 numerous sections of the updated walkdown report where peer review work is discussed, mainly, Sections 4, 7 and 9. The licensee emphasized that no individual performing a given walkdown activity was a peer team member for that same activity.

The NRC staff reviewed the licensee's summary of each of these activities, which included the peer review team members' 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 of External Events for Severe Accident Vulnerabilities

- 10 CFR 50.54(f)," dated November 23, 19888 ," licensees previously had performed a systematic examination to identify any plant-specific vulnerabilities to severe accidents.

The licensee provided information on seismic vulnerabilities in Attachment 5 of the walkdown report. Each entry contains the equipment ID number, equipment description, location, outlier description, outlier resolution, and modification status. The licensee stated that a previous walkdown performed in May of 2012 had identified two (2) outliers that were potentially unresolved. The licensee stated that CAP entries were generated and the issues have been resolved. Table 8-1 of the submittal indicates that a CAP entry was issued to address this and the issue has been resolved.

Based on the NRC staff's review of Section 7 of the walkdown report, the NRC staff concludes that the licensee's identification of plant-specific vulnerabilities (including anomalies, outliers and other findings) identified by the IPEEE program, as well as actions taken to eliminate or reduce them, 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 VEGP-2 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 February 1, 2013, 10 documents the results of this inspection. No findings were identified.

8 ADAMS Accession No. ML031150465 9

ADAMS Accession No. ML12156A052 10 ADAMS Accession No. ML 13003021

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 NRC licensee responded appropriately to Enclosure 3 of the 50.54(f) letter, dated March 12, 2012.

C. R. Pierce The NRC staff reviewed the information provided and, as documented in the enclosed staff assessment, determined that sufficient information was provided to be responsive to Enclosure 3 of the 50.54(f) letter. This concludes the NRC's efforts associated with TAC No. MF0190.

Sincerely, IRA/

Robert Martin, Senior Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-425

Enclosure:

Staff Assessment of Seismic Walkdown Report cc w/encl: Distribution via Listserv DISTRIBUTION:

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DATE 02/21/14 02/20/14 2/11/2014 OFFICE DORL/LPL2-1/BC DORLILPL2-1/PM NAME RPascarelli RMartin DATE 02/24/14 02/24/14 OFFICIAL RECORD COPY