ONS-2013-031, Response to Request for Additional Information Regarding the Seismic Hazard Walkdowns Associated with Near-Term Task Force Recommendation 2.3, Seismic Walkdowns

Response to Request for Additional Information Regarding the Seismic Hazard Walkdowns Associated with Near-Term Task Force Recommendation 2.3, Seismic Walkdowns

ML13330B685
Person / Time
Site:	Oconee
Issue date:	11/25/2013
From:	Batson S Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
ONS-2013-031
Download: ML13330B685 (9)

Text

i DUKE Scott L.Batson Vice President ENERGYe Oconee Nuclear Station Duke Energy ONO I VP 17800 RochesterHwy Seneca, SC 29672 ONS-2013-031 o: 864.873.3274 f 864.873. 4208 November 25, 2013 Scott.Batson@duke-energy.com ATTN: Document Control Desk 10 CFR 50.54 (f)

U. S. Nuclear Regulatory Commission Washington, DC 20555-0001 Duke Energy Carolinas, LLC (Duke Energy)

Oconee Nuclear Station (ONS), Unit Nos. 1, 2, and 3 Docket Nos. 50-269, 50-270, and 50-287 Renewed License Nos. DPR-38, DPR-47, and DPR-55

Subject:

Response to Request for Additional Information Regarding the Seismic Hazard Walkdowns Associated With Near-Term Task Force Recommendation 2.3, Seismic Walkdowns

References:

1. NRC Letter, Request for Information Pursuantto Title 10 of the Code of FederalRegulations 50.54(f) Regarding Recommendations 2.1, 2.3, and 9.3, of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichiAccident, dated March 12, 2012, ADAMS Accession No. ML12053A340

2. Electrical Power Research Institute (EPRI) Seismic Walkdown Guidance, ForResolution of Fukushima Near-Term Task Force Recommendation 2.3: Seismic, EPRI Report 1025286, dated June 2012, ADAMS Accession No. ML12188A031

3. Duke Energy Letter, Duke Energy Carolinas,LLC (Duke Energy), Oconee Nuclear Station (ONS), Units 1, 2 and 3, Docket Nos. 50-269, 50-270, and 50-287, Seismic Walkdown Information Requested by NRC Letter, Request for Information Pursuantto Title 10 of the Code of FederalRegulations 50.54(f) RegardingRecommendations 2.1, 2.3, and 9.3, of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichiAccident; dated November 27, 2012, ADAMS Accession No. ML12347A252

4. Duke Energy Letter, Duke Energy Carolinas,LLC (Duke Energy), Oconee Nuclear Station (ONS), Units 1, 2 and 3, Docket Nos. 50-269, 50-270, and 50-287, ONS Unit 1 Update to the ONS Seismic Walkdown Information Submitted November 27, 2012, dated July 1, 2013, ADAMS Accession No. ML13192A155

5. NRC Letter, Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3, Seismic Walkdowns dated November 1, 2013, ADAMS Accession No. ML13304B418 Ladies and Gentlemen:

On March 12, 2012, the Nuclear Regulatory Commission (NRC) staff issued a letter requesting information per Title 10 to the Code of FederalRegulations, Section 50.54(f) (i.e., Reference 1).

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United States Nuclear Regulatory Commission Seismic Walkdown RAI November 25, 2013 Page 2 The letter requested licensees to conduct seismic hazard walkdowns to verify current plant configuration with the current licensing basis (CLB).

Duke Energy Carolinas, LLC (Duke Energy) conducted the requested walkdowns using the NRC endorsed, Electric Power Research Institute (EPRI) guidance (Reference 2). Duke Energy submitted seismic walkdown reports for Oconee Nuclear Station (ONS) by letters dated November 27, 2012, and July 1, 2013, (References 3 and 4). By letter dated November 1, 2013, (Reference 5) the NRC has requested additional information related to the seismic walkdowns.

The Duke Energy response for ONS is enclosed.

This letter contains no new regulatory commitments.

If you have any questions regarding this submittal, please contact David Haile, Oconee Regulatory Affairs at 864-873-4742.

I declare under penalty of perjury that the foregoing is true and correct. Executed on November 25, 2013.

Sincerely, Scott L. Batson, Vice President, Oconee Nuclear Station

Enclosure:

Oconee Nuclear Station Units 1, 2 and 3 Response to the NRC Request for Additional Information Regarding Seismic Walkdowns

United States Nuclear Regulatory Commission Seismic Walkdown RAI November 25, 2013 Page 3 xc (with enclosures):

Mr. Victor McCree, Regional Administrator U.S. Nuclear Regulatory Commission - Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, Georgia 30303-1257 Mr. Eric Leeds, Director, Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission One White Flint North, Mailstop 13-H16M 11555 Rockville Pike Rockville, MD 20852-2738 Mr. Richard Guzman, Project Manager (ONS)

(by electronic mail only)

U.S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop O-8C2 Rockville, MD 20852 Mr. Eddy Crowe NRC Senior Resident Inspector Oconee Nuclear Station

Enclosure Oconee Nuclear Station Units 1, 2, and 3 Response to the NRC Request for Additional Information Regarding Seismic Walkdowns (datedNovember 1, 2013)

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Enclosure Oconee Nuclear Station Units 1, 2, and 3 Response to the NRC Request for Additional Information Regarding Seismic Walkdowns NRC Question 1: Conduct of the walkdowns. determination of Potentially adverse seismic conditions (PASCs), dispositionina of issues, and reportina 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 an 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 of field observations that were deemed not to be PASCs. However, the basis for the determination was not clearly recorded. In some cases, the field checklists were amplified by noting that the basis was engineering judgment.

During site audit discussions, the staff was able to trace the basis for the engineering judgments and found that in 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 a field 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 staff found 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-E2

Enclosure Oconee Nuclear Station Units 1, 2, and 3 Response to the NRC Request for Additional Information Regarding Seismic Walkdowns 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, please 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 a field 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 the 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 condition, how it was dispositioned and the basis for the disposition, as follows: 1) for each condition that was entered into the CAP, provide the CAP reference number, initiation date, and (if known) 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.

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Enclosure Oconee Nuclear Station Units 1, 2, and 3 Response to the NRC Request for Additional Information Regarding Seismic Walkdowns Response to Question 1:

Based on the NRC's question, and a review of Oconee's submittal, the alternative described by 1(c) was determined to be the applicable response, therefore, there are no new Potentially Adverse Seismic Conditions (PASC) to report because all PASC items were addressed and included in the prior submittals.

The following is the description of the walkdown process, as discussed in the Duke Energy November 27, 2012 submittal (Reference 3, Attachment 5 to Enclosure 1, 2, or 3) and is applicable to the process used in all three units:

• "The Shaw / ARES methodology conforms to the guidance in Section 4 of EPRI 1025286. The equipment items and areas to be walked down were specified in the Seismic Walkdown Equipment List (SWEL) provided by Duke. The walkdowns consist of two parts: equipment-specific seismic walkdowns, and area walk-bys. The specific instructions for each part are delineated in EPRI 1025286."

• "Seismic walkdowns of specific items on the SWEL (SWEL 1 plus SWEL 2) focused on identifying adverse anchorage conditions, adverse seismic interactions, and other adverse seismic conditions that could challenge the seismic adequacy of a SWEL item."

• "Anchorage was examined for degraded, nonconforming, or unanalyzed conditions. This included visual inspection of the anchorage and verification of anchorage condition. The visual inspections looked for bent, broken, missing or loose hardware; corrosion that is more than mild surface oxidation; visible cracks in the concrete near anchors; and other potentially adverse seismic conditions. This did not apply to line-mounted items. Where possible, cabinets and enclosures were opened for examination of internals."

• "Anchorage configuration was verified to be consistent with the existing plant documentation. This applied to equipment designated in the SWEL as requiring anchorage configuration verification (at least 50% of non-line-mounted SWEL items)."

" "The area adjacent to and surrounding the SWEL item was inspected for nearby structures, systems, and components that could be seismic interaction hazards due to proximity, failure and falling, or insufficient flexibility of attached lines and cables.

Detailed guidance on seismic spatial interactions is given in Appendix D of EPRI 1025286."

• "The SWEL item was also examined to see ifthere were any other potentially adverse seismic conditions besides anchorage and seismic interaction. These could include other degraded conditions, loose or missing subcomponent fasteners, unusual large or heavy subcomponents, doors or panels not latched or fastened, or any other condition that might be seismically adverse."

" "Area walk-bys consisted of examining the general area surrounding the specific SWEL items for potentially adverse seismic conditions. The area examined included either the entire room enclosing the SWEL item or at least 35 feet in any direction. The examination looked for degraded anchorage conditions of equipment in the area; significantly degraded equipment; poorly supported cable / conduit raceways, HVAC E4

Enclosure Oconee Nuclear Station Units 1, 2, and 3 Response to the NRC Request for Additional Information Regarding Seismic Walkdowns ducting, or piping; and unsecured temporary equipment that could cause seismic interactions (seismic housekeeping concerns). The area walk-by included looking for potential seismic interactions from flooding, spray, or fire. These potential seismic interactions are described in Section 4 of EPRI 1025286."

0 If the Seismic Walkdown Engineers (SWEs) determined a potentially adverse seismic condition existed, using engineering judgment based on their experience and training with the EPRI Guidance (Section 5), then the issue was entered into the corrective action program (CAP) to allow further engineering evaluation. The CAP engineering evaluation determined whether the potentially adverse seismic condition was degraded, unanalyzed, or non-conforming to the design and licensing bases.

Section 5 (of each enclosure/unit) in Oconee's original submittal (Reference 3), addressed potential adverse conditions found during the Walkdowns and Area Walk-bys in a paragraph similar to the following:

A total of [number] potential adverse conditions were identified per the Seismic Walkdowns and the Area walk-bys. All of these potential issues were entered into the Corrective Action Program (CAP). All potential adverse conditions were evaluated for their compliance with the seismic licensing basis within the CAP and were found to be acceptable. Station Work Requests were written for some conditions as good practice. The potentially adverse conditions and their individual Problem Investigation process (PIP) tracking numbers are listed in the NTTF 2.3 Seismic Walkdown Report for Unit [1, 2, or 3] contained in Attachment 5.

While the number of PASCs varied among the units, the preceding wording describes the method used to identify, track and address the PASCs. Note that Reference 4, is an update to the original submittal which walked down Unit 1, and common items which were inaccessible during the initial walkdowns. There were no new PASCs identified from the walkdown of these items.

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Enclosure Oconee Nuclear Station Units 1, 2, and 3 Response to the NRC Request for Additional Information Regarding Seismic Walkdowns NRC Question 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, if at all, described in the walkdown guidance.

Therefore, in order to clarify 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. Ifthere 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, ifthere are differences from the original submittal, please provide a description of the above information. Ifthere are differences in the review areas or the manner in which the peer reviews were conducted, describe the actual process that was used.

Response to Question 2:

Section 7 (of each enclosure/unit) in Oconee's original submittal (Reference 3) contains a description of the peer review process. Additionally, the original submittal, and the update submittal (Reference 4) included a separate peer review report organized to emphasize activities identified in Section 6 (Page 6-1) of Reference 2. The report is contained as to each enclosure/unit for the original submittal and the update submittal. A complete summary of the peer review activities is contained in those attachments. Table 2-1 of each enclosure for both submittals (Reference 3 and Reference 4), illustrates that the Peer Review Team was independent of the seismic walkdown-related activities.

Note: Reference numbers cited in this enclosure align with the Reference list of the cover letter.

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