ML14084A327
| ML14084A327 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 03/27/2014 |
| From: | V Sreenivas Plant Licensing Branch II |
| To: | Heacock D Virginia Electric & Power Co (VEPCO) |
| Sreenivas V, NRR/DORL/LPL2-1, 415-2597 | |
| References | |
| TAC MF0148 | |
| Download: ML14084A327 (12) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 March 27, 2014 Mr. David A. Heacock President and Chief Nuclear Officer Virginia Electric and Power Company lnnsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711
SUBJECT:
NORTH ANNA POWER STATION, 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. MF0148)
Dear Mr. Heacock:
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 January 30, 2014, Virginia Electric and Power Company (Dominion) submitted its Seismic Walkdown Report as requested in of the 50.54(f) letter for the North Anna Power Station, Unit 2. By letter dated November 27, 2013, Dominion provided a response to the NRC request for additional information for the NRC staff to complete its assessments.
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.
D. Heacock If you have any questions, please contact me at 301-415-2597 or by e-mail at V.Sreenivas@nrc.gov Sincerely,
. Sreenivas, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-339
Enclosure:
Staff Assessment of Seismic Walkdown Report for NAPS, 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 VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION, UNIT 2 DOCKET NO. 50-339
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 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 walkdown process. By letter dated May 29, 2012, 3 the Nuclear Energy Institute (NEI) staff 1
Agencywide Documents Access and Management System (ADAMS) Accession No. ML12053A340 2
ADAMS Accession No. ML12056A049 3
ADAMS Package Accession No. ML121640872 Enclosure
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 27, 2012, 5 Virginia Electric and Power Company (the licensee) provided a response to Enclosure 3 of the 50.54(f) letter Required Response Item 2, for North Anna Power Station Unit (NAPS) 2. In addition to the aforementioned letter, the licensee, by letter dated January 30, 20146 provided a supplement to the walkdown report. The updated report provides the results for the deferred seismic walkdowns of components which were inaccessible during the initial walkdowns. 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 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. 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 licensee was required to develop and maintain design bases that, as defined by 10 CFR 50.2, identify the specific functions that an SSG 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, 4
ADAMS Accession No. ML12145A529 5
ADAMS Accession No. ML12355A060 6
ADAMS Accession No. ML14036A315 7
ADAMS Accession No. ML133048418 8
ADAMS Accession No. ML13338A167
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 NAPS2 in Section 1.0 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 NRC staff reviewed Section 1.0 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 provide information to licensees regarding the implementation of an appropriate seismic walk down methodology. By letter dated July 2, 2012, 9 the licensee confirmed that it would utilize the walkdown guidance in the performance of the seismic walkdowns at NAPS2.
The walkdown report dated November 27,2012, and updated on January 30, 2014, did not identify deviations from the walkdown guidance. However, the NRC staff noted that the licensee submitted a combined report for North Anna, Units 1 and 2, which is a deviation from the walkdown guidance. The NRC staff reviewed the combined report and noted that the licensee provided separate seismic walkdown equipment lists (SWELs) and checklists for each unit.
Therefore, the NRC staff concludes that the submittal of one report for both units, although a deviation from the walkdown guidance, is acceptable.
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 9
ADAMS Accession No. ML121910343
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 2 and Appendix A of the 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.
- The NRC staff noted that the walkdown report specifies that Operations staff, including licensed operators and design and system engineering personnel, supported the selection of equipment in the walkdown activities. The licensee did not identify or summarize the background and experience for the involved Operations staff. However, since licensed plant operators are qualified by the NRC and continuously train to maintain their license, licensed plant operators have the appropriate operations knowledge and experience to support the seismic walkdown activities.
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 NAPS2 base list, SWEL 1 (sample list of designated safety functions equipment), and SWEL 2 (sample list of spent fuel pool related equipment). 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, NAPS2 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 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 3.3 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 (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 adequate justification for not including rapid drain-down items as part of the SWEL 2.
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 4 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 from July 23, 2012 to October 10, 2012. In addition, a subsequent set of walkdowns were performed on January 14, 2013 and between April 13, 2013 and April 22, 2013, as stated in the January 30, 2014 letter from the licensee. The purpose of the last activity was to complete a number of items that were inaccessible during the initial walkdowns. 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 E 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 4-2 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 initial review of the checklists, the 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 confirmed that observations that could not be readily judged to be acceptable with respect to its current licensing basis during the walkdown, and not found to be previously evaluated as acceptable conditions through follow-up review of plant documentation, were identified as PASCs and documented as condition reports in the CAP. The licensee referred to Table 4-2 of the walkdown report which includes all the PASCs identified during the walkdowns and area walk-bys for NAPS2. Also, in response to RAI 1, the licensee stated that a low threshold was used to identify and document PASCs. The licensee clarified that in addition to the items included in Table 4-2, non-seismic potentially adverse conditions, such as housekeeping and material conditions items, identified by SWEs were addressed through the CAP.
After evaluating the licensee's response and reviewing Table 4-2, the NRC staff concludes that the licensee responded appropriately to RAI 1, PASCs were properly identified and documented and summary Table 4-2 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. In some cases, as documented on the SWCs, the licensee credited anchorage inspections performed within the last 12 months by a SQUG-qualified seismic capacity engineer for the anchorage verification portion of the walkdowns.
The revised walkdown report states that the licensee opened cabinets as part of the subsequent walkdowns. The NRC staff noted that these internal cabinet inspections were recorded in the SWCs.
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 NAPS2 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 4-2 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 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 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 7 of the NAPS2 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 the summary of the peer review activities provided in Section 7 of the walkdown report. In addition, the licensee provided additional information on the level of involvement of the peer review team and its leader in order to further demonstrate the independence of the peer review process.
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 (GL) 88-20, "Individual Plant Examination of External Events for Severe Accident Vulnerabilities- 10 CFR 50.54(f)," dated November 23, 198810 , licensees previously had performed a systematic examination to identify any plant-specific vulnerabilities to severe accidents.
The walkdown report does not include any tables regarding IPEEE vulnerabilities but stated that the results of this program were submitted to the NRC staff in the licensee's Summary Report for IPEEE- Seismic dated May 27, 1997. The licensee indicated that this report concluded that there were no severe accident vulnerabilities associated with seismic event and therefore, no major plant modifications were necessary.
Based on the NRC staff's review of Section 6 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, 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 NAPS2 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 30, 2013, 12 documents the results of this inspection and states that no findings were identified.
10 ADAMS Accession No. ML031150465 11 ADAMS Accession No. ML12156A052 12 ADAMS Accession No. ML13031A312
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 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 NRC staff notes that no immediate safety concerns were identified. The NRC staff reviewed the information provided and determined that sufficient information was provided to be responsive to of the 50.54(f) letter.
D. Heacock If you have any questions, please contact me at 301-415-2597 or by e-mail at V.Sreenivas@nrc.gov.
Sincerely, Ira/
V. Sreenivas, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-339
Enclosure:
Staff Assessment of Seismic Walkdown Report for NAPS, Unit 2 cc w/encl: Distribution via Listserv DISTRIBUTION:
PUBLIC MJardaneh, NRO RidsRgn2MaiiCenter Resource LPL2-1 R/F RidsOpaMail Resource BRini, EDO Rl, Rll, Rill, RIV RidsNroDsea RidsNrrLASFigueroa Resource RidsAcrsAcnw MaiiCTR Resource RidsNrrDorl Resource RidsNrrPMNorthAnna Resource RidsNrrDorllpl2-1 Resource NDiFrancesco, NRR NChokshi, NRO SFianders, NRO DJackson, NRO RKaras, NRO FVega, NRO ADAMS Accession Number: ML14084A327
- concurrence by e-mail OFFICE DORLILPL2-1/PM DORL/LPL2-1/LA JLD/PMB/PM NAME VSreenivas SFigueroa NDiFrancesco DATE 3/27/14 3/26/14 3/27/14 OFFICE DSEA/RGS2 DORL/LPL2-1/BC DORLILPL2-1/PM NAME DJackson* RPascarelli VSreenivas DATE 3/18/2014 3/27/14 3/27/14 OFFICIAL RECORD COPY