NLS2013099, Response to Nuclear Regulatory Commissions Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3, Seismic Walkdowns
| ML13330B000 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 11/21/2013 |
| From: | Limpias O Nebraska Public Power District (NPPD) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NLS2013099 | |
| Download: ML13330B000 (9) | |
Text
Nebraska Public Power District Always there when you need us NLS2013099 November 21, 2013 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk 11555 Rockville Pike Rockville. MD 20852
Subject:
Nebraska Public Power District's Response to Nuclear Regulatory Commission's Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3, Seismic Walkdowns Cooper Nuclear Station, Docket No. 50-298, DPR-46
References:
- 1. NRC Letter, Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(l) Regarding Recommendations 2.1, 2.3, and 9.3, of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, dated March 12, 2012 (ML12053A340)
- 2. NRC Letter to NEI, Endorsement of Electric Power Research Institute (EPRI)
Draft Report 1025286, "Seismic Walkdown Guidance," dated May 31, 2012 (ML12145A529)
- 3. Electrical Power Research Institute (EPRI) Report 1025286, Seismic Walkdown Guidance, For Resolution of Fukushima Near-Term Task Force Recommendation 2.3: Seismic, dated June 2012 (ML12188A031)
- 4. NRC Letter, Request for Additional Information Associated With Near-Term Task Force Recommendation 2.3, Seismic Walkdowns, dated November 1, 2013 (ML13304B418)
- 5. NPPD Letter to NRC, Seismic Walkdown Report - Nebraska Public Power District's Response to Nuclear Regulatory Commission Request for Information Pursuant to 10 CFR 50.540W Regarding the Seismic Aspects of Recommendation 2.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, dated November 27, 2012 (NLS2012125)
- 6. Internal NRC Memorandum, Summary of the September 12, 2013, Public Meeting to Discuss Implementation of Japan Lessons-Learned Near-Term Task Force Recommendation 2.3, Seismic Walkdowns, dated October 4, 2013 (ML13266A424)
COOPER NUCLEAR STATION ADDC)
P.O. Box 98 / Brownville, NE 68321-0098 Telephone: (402) 825-3811 / Fax: (402) 825-5211 www.nppd.com
NLS2013099 Page 2 of 3
Dear Sir or Madam:
On March 12, 2012, the Nuclear Regulatory Commission (NRC) issued Reference I to all power reactor licensees. Enclosure 3 of Reference 1 requested licensees to conduct seismic hazard walkdowns to verify current plant configuration with the current licensing basis. The NRC endorsed an Electric Power Research Institute (EPRI) guidance document (References 2 and 3),
and determined that the use of the EPRI guidance would meet the objectives and requests of Reference 1.
Nebraska Public Power District (NPPD) submitted the Seismic Walkdown Report for Cooper Nuclear Station (CNS) on November 27, 2012 (Reference 5).
Following the NRC's initial review of the walkdown reports, regulatory site audits were conducted at a sampling of plants. By internal NRC correspondence (Reference 6) the NRC summarized the public webinar conducted on September 12, 2013, and provided written questions identifying the areas where additional information could assist the NRC staff in completing their reviews of the walkdown reports. These questions were consolidated and on November 1, 2013, Reference 4 was issued by the NRC requesting additional information (RAI).
Attachment I provides NPPD's response to the RAI for CNS.
This letter contains no new regulatory commitments. Should you have any questions regarding this submittal, please contact David Van Der Kamp, Licensing Manager, at (402) 825-2904.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on:
t-t Sinc4e\\)
bg'~~Eirnpias/
Vice President - Nuclear and Chief Nuclear Officer
/bk
Attachment:
Response to Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3, Seismic Walkdowns cc:
Regional Administrator, w/attachment USNRC - Region IV Director, w/attachment USNRC - Office of Nuclear Reactor Regulation Cooper Project Manager, w/attachment USNRC - NRR Project Directorate IV-I
NLS2013099 Page 3 of 3 Senior Resident Inspector, w/attachment USNRC - CNS NPG Distribution, w/attachment CNS Records, w/attachment
NLS2013099 Attachment Page 1 of 6 Attachment Response to Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3, Seismic Walkdowns Cooper Nuclear Station, Docket No. 50-298, DPR-46 On March 12, 2012, the Nuclear Regulatory Commission (NRC) issued a letter requesting additional information per 10 CFR 50.54(f). The request for information letter requested that licensees conduct seismic hazard walkdowns to verify the plant configuration with the current licensing basis (CLB). Licensees stated by letter that the seismic walkdowns would be performed in accordance with Electric Power Research Institute (EPRI) Report 1025286, "Seismic Walkdown Guidance for Resolution of Fukushima Near-Term Task Force (NTTF)
Recommendation 2.3: Seismic" (walkdown guidance). Following the NRC's initial review of the walkdown reports, regulatory site audits were conducted at a sampling of plants. Based on the walkdown report reviews and site audits, the staff identified additional information necessary to allow the staff to complete its assessments.
Below are the NRC's request for information (RAI) and Nebraska Public Power District's (NPPD) responses to the RAIs.
NRC RAI #1: Conduct of the walkdowns, determination of potentially adverse seismic conditions (PASCs), dispositioning of issues, and reporting As a result of the audits and walkdown report reviews, the NRC staff noted that licensees' interpretations of the seismic walkdown guidance varied, which resulted in meaningful differences in the process used to disposition identified issues and in the documentation that was provided to the NRC staff In particular, the application of engineering judgment in determining what constituted a potentially adverse seismic condition (PASC), the threshold for conducting licensing basis evaluations (LBEs), and determining what information was to be reported to the NRC staff varied.
The NRC staff intended that conditions initially marked No (N) or Unknown (U) in the field by the seismic walkdown engineers (SWEs) for which an analysis or calculation was performed would be considered as PASCs and that an analysis or calculation constituted a LBE. The walkdown guidance allows for analysis as part of engineering judgment; however, the intent was to allow for only simple analyses that could be readily performed in support of engineering judgment. Further, the walkdown activities were intended to allow for transparency in the licensee's process to demonstrate that PASCs were appropriately identified, that they were addressed in an appropriate manner, and the basis documented such that the current condition of the plant was clearly consistent with the CLB with regard to seismic capability.
During the audits, the NRC staff identified examples offield observations that were deemed not to be PASCs. However, the basis for the determination was not clearly recorded. In some cases,
NLS2013099 Attachment Page 2 of 6 the field checklists were amplified by noting that the basis was engineeringjudgment. During site audit discussions, the staff was able to trace the basis for the engineeringjudgments and found that many cases they were appropriate. It is expected that these situations would not be included in the walkdown report.
There were other situations that a PASC and LBE were not reported; however the NRC staff found during the audit that a calculation, analysis (more than just simple), or evaluation was conducted but informally. An example is a confirmatory calculation performed to demonstrate that six anchor bolts out of eight was not a seismically adverse condition. Another example would be an analysis to demonstrate that an existing, slightly short weld was as seismically sound as the prescribed weld length in the plant design documentation. The staff expected these types of conditions and evaluations to be captured in the licensee's normal plant processes (e.g.,
condition report or corrective action program) (CAP), and also reported in the walkdown report, since they were potentially adverse seismic conditions that required more than applying judgment or simple analysis to address.
The NRC staff also found that the process that was used to deal with afield observation that was deemed to be a PASC was also not completely described or captured in the report. In many cases, the licensee reported that an LBE was not performed. However, during the audits it was clear that an LBE (or an equivalent determination method) was performed and used in determining whether a PASC should be entered into the CAP. The staff expects that these conditions would be reported in the walkdown report.
On the whole, through the audits, the NRC stafffound that it was able to conclude that the intent of the guidance was met when the licensee's overall process was completely explained, the information was updated to reflect the actual process, and results were updated. The self-assessments conducted by the licensees of the audited plants also identified the lapse in the description of the process used by the licensee to identify a PASC and disposition it.
Therefore, in order to clarify the process that was followed, provide a description of the overall process used by the licensee (and its contractors) to evaluate observations identified in the field by the SWEs. The process should include how afield observation was determined to be a PASC or not and how the bases for determinations were recorded. Once a determination was made that an observation was a PASC, describe the process for creating a condition report (or other tracking mechanism), performing the LBE (or other determination method), and the resultant action, such as entering it into CAP, or documenting the result and basis.
Also, in order to confirm that the reported information supports concluding that the plant meets the CLB, please follow one of the following three acceptable alternatives:
a) Provide a supplement to the table or text from the original walkdown report, if needed, to include similar conditions as the above examples and situations and for conditions for which a calculation, analysis (if more than a simple analysis), or evaluation was used for a determination. The supplement should include a short description of each
NLS2013099 Attachment Page 3 of 6 condition, how it was dispositioned and the basis for the disposition, asfollows: 1)for each condition that was entered into the CAP, provide the CAP reference number, initiation date, and (ifknown) the planned completion date, or 2)for all other conditions, provide the result of the LBE (or other determination method), the basis for the result, and how (or where) the result was captured in the plant's documentation or existing plant process.
b) Following the plant's standard procedures, confirm that a new CAP entry has been made to verify if appropriate actions were taken when reporting and dispositioning identified PASCs (including conditions for which a calculation, analysis (if more than a simple analysis), or evaluation was used for a determination). The eventual CAP closeout, including the process followed and actions taken, should be in sufficient detail to enable NRC resident inspectors to follow up.
c) If no new conditions are identified for addition to the supplement or the CAP entry mentioned above is deemed not necessary, provide a statement of confirmation that all potentially seismic adverse conditions (including conditions for which a calculation, analysis (if more than a simple analysis), or evaluation was used for a determination) identified during the walkdowns and walk-bys were addressed and included in the report to the NRC.
NPPD Response:
In November of 2012, NPPD documented the results of the seismic walkdown effort undertaken at Cooper Nuclear Station (CNS) for resolution of NTTF Recommendation 2.3: Seismic, in accordance with industry guidance, and provided the information necessary for responding to of the 50.54(f) request for information letter. The industry guidance document, EPRI Report 1025286, was formally endorsed by the NRC on May 31, 2012. NPPD committed to using this NRC-endorsed guidance as the basis for conducting and documenting seismic walkdowns.
To supplement the site workforce, NPPD hired Zachry Holdings, Inc. to perform the walkdowns and the report with CNS assistance, and hired Tetra Tech Nuclear to perform a peer review of the walkdowns and a peer review of the report.
Seismic walkdowns were performed in accordance with Section 4 of the EPRI guidance for the items on the Seismic Walkdown Equipment List (SWEL 1 plus SWEL 2), except for those determined to be inaccessible and deferred (see Section 5.7 of the CNS Seismic Walkdown Report). To document the results of the walkdowns, a Seismic Walkdown Checklist (SWC) with the same content as that included in Appendix C of the EPRI Guidance was created for the SWEL items. Additionally, where permitted by CNS Operations and Security personnel, photographs were taken of the item and included on the corresponding final revision of the SWC.
NLS2013099 Attachment Page 4 of 6 During the course of the seismic walkdowns and area walk-bys, the objective of the Seismic Walkdown Engineer (SWE) teams was to identify existing degraded, non-conforming, or unanalyzed plant conditions with respect to its current seismic licensing basis. When an unusual condition was observed by a SWE team in the field, the condition was noted on the SWC or Area Walk-by Checklist (AWC) form and briefly discussed between the two SWEs to agree upon whether it was a potentially adverse seismic condition (PASC). These initial conclusions were based on conservative engineering judgment and the training required for SWE qualification.
The walkdown sheets were annotated where appropriate with supporting reference or justification for the basis of its acceptance. The walkdown sheets included an explanation regarding why some field conditions were not identified as PASC.
For conditions that were reasonably judged as insignificant to seismic response, the disposition was included on the SWC or AWC checklist and the appropriate question was marked "Y" indicating that a PASC was not observed. Unusual or uncertain conditions were reported for further resolution through CNS' Corrective Action Program (CAP) (see Section 6.1 of the CNS Seismic Walkdown Report).
For conditions that were judged as potentially significant to seismic response, the condition was photographed, and the appropriate question on the SWC or AWC was marked "N" indicating that a PASC was observed. The condition was then researched further. The component or area was walked down a second time by the SWEs if documentation supported a second inspection.
Following the research and, in some cases, a second inspection by the SWEs, the condition was determined to be in compliance with CNS' licensing basis and dispositioned accordingly (on the SWC or AWC), or the condition was entered into the CAP (see Section 6.1 of the CNS Seismic Walkdown Report). The SWEs did not complete informal analysis or calculations (i.e., licensing basis evaluations) for the disposition of these conditions. In the event that an analysis or calculation was necessary, the condition was entered into the CAP.
Conditions observed during the seismic walkdowns and area walk-bys determined to be a PASC are summarized in Section 6.1 of the CNS Seismic Walkdown Report, including the status of the conditions at the time of report submission. PASCs were entered into the CAP directly.
The conditions that were discovered during the walkdowns were entered into the CAP. A copy of the condition reports can be found in Attachment E of the CNS Seismic Walkdown Report.
After further review of the CNS Seismic Walkdown Report, NPPD confirms that the reported information supports the conclusion that CNS meets its CLB in accordance with alternative (c) listed in the RAI Question 1. The PASCs identified during the walkdowns and walk-bys were addressed and included in CNS' Seismic Walkdown Report submitted to the NRC.
NLS2013099 Attachment Page 5 of 6 NRC RAI #2: Conduct of the Peer Review Process As a result of the walkdown report reviews, the NRC staff noted that some descriptions of the peer reviewers and the peer review process that was followed were varied and, in some cases, unclear. In some cases, the staff could not confirm details of the process, such as if the entire process was reviewed by the peer review team, who were the peer reviewers, what was the role of each peer reviewer, and how the reviews affected the work, ifat all, described in the walkdown guidance.
Therefore, in order to clarifjy the peer review process that was actually used, please confirm whether the following information on the peer review process was provided in the original submittal, and if not, provide the following:
a) Confirmation that the activities described in the walkdown guidance on page 6-1 were assessed as part of the peer review process.
b) A complete summary of the peer review process and activities. Details should include confirmation that any individual involved in performing any given walkdown activity was not a peer reviewer for that same activity. If there were cases in which peer reviewers reviewed their own work, please justify how this is in accordance with the objectives of the peer review efforts.
Also, if there are differences from the original submittal, please provide a description of the above information. If there are differences in the review areas or the manner in which the peer reviews were conducted, describe the actual process that was used.
NPPD Response:
The activities listed on page 6-1 of the EPRI guidance were assessed as part of the peer review process. This peer review was originally documented in Section 9 of the CNS Seismic Walkdown Report.
The approach for the peer review was based on the guidance provided in EPRI 1025286. The peer review team was composed of 4 engineers (1 peer review lead, 2 subject matter experts and 1 additional engineer) with varied backgrounds and relevant expertise which were documented by the inclusion of the team members' resumes in Attachment F of the original seismic walkdown report.
The peer review team was completely independent from the team performing the walkdowns (from a different company) and as such, no individual peer reviewed their own work. The peer team reviewed:
the selection of structures, systems and components, the qualifications of the SWEs,
NLS2013099 Attachment Page 6 of 6
" over 10% of the walkdown packages (including Screening Evaluation Worksheets, checklists, etc.),
" the licensing basis evaluation approach (Note: conditions were entered directly into the CAP rather than completion of informal analysis or calculations),
" the basis for entering items into the CAP process, and
" the original seismic walkdown report.
In accordance with the EPRI guidance, a summary of the peer review results was included in the original seismic walkdown report submitted to the NRC.