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EA-04-115 - Oconee 1, 2, 3 (Duke Energy Corporation)September 24, 2004 Duke Energy Corporation
Dear Mr. Jones: The purpose of this letter is to provide you with the Nuclear Regulatory Commission’s (NRC’s) final significance determination for a finding at Duke Energy Corporation’s (DEC’s) Oconee Nuclear Station involving fire response procedures that were not consistent with the licensing basis in regards to the criteria for manning of the Standby Shutdown Facility (SSF). In some scenarios, this could result in a delay of transfer of control to the SSF that could challenge the capability of the installed SSF makeup pump. This condition could result in the failure to maintain pressurizer level within the indicating range as required by 10 CFR 50, Appendix R. The finding was documented in NRC Inspection Report 05000269,270,287/2004012, dated July 20, 2004, and was assessed under the significance determination process as a preliminary greater than Green issue for all three Oconee units (i.e., an issue of at least low to moderate safety significance, which may require additional NRC inspection). The cover letter to the inspection report informed DEC of the NRC’s preliminary conclusion, provided DEC an opportunity to request a regulatory conference on this matter, and forwarded the details of the NRC’s preliminary estimate of the change in core damage frequency (CDF) for this finding. At your request, an open regulatory conference was conducted with members of your staff on September 13, 2004, to discuss DEC’s position on this issue. The enclosures to this letter include the list of attendees at the regulatory conference, and copies of the material presented by your staff and the NRC at the regulatory conference. During the conference, DEC provided the results of its review of the safety significance of the finding and highlighted the modeling and assumption differences between its analysis of the change in CDF and that of the NRC’s preliminary estimate. In addition, DEC agreed with the NRC’s characterization of the finding as a violation of regulatory requirements, and stated that DEC strategy and procedures have been revised to man the SSF upon identification of a confirmed fire in the specified fire areas of concern. A particular focus of DEC’s presentation was a substantive difference in the assumed failure probability of Oconee’s primary safety relief valves (PSVs). DEC stated at the conference that the NRC’s PSV failure probability used in its preliminary estimate was very conservative for Oconee’s scenario. To determine a PSV failure probability that was specific to Oconee, DEC convened an Expert Elicitation Panel, commissioned with the Electric Power Research Institute. DEC explained the Expert Elicitation Panel Process in detail, and stated that its goal was to obtain a PSV “failure to reseat” probability based on test data, plant experience, and expert judgment. As described by DEC, the failure probability also considered the range of factors unique to Oconee’s PSVs that may affect valve performance, such as lift type, inlet piping configuration, and fluid conditions. Based on the efforts of the Expert Elicitation Panel, DEC concluded that the important factors in determining PSV failure rate were inlet piping configuration, fluid conditions, and the number of cycles. Regarding the factor of inlet piping configuration, DEC concluded that because the Oconee configuration is a short inlet pipe with no loop seal, its physical configuration is the most reliable relative to other piping configurations. Secondly, DEC concluded that PSV reliability is highest when relieving steam. Because the relieving fluid conditions at Oconee, for these scenarios, are expected to be steam, DEC stated that this factor would result in a higher PSV reliability relative to other fluid conditions such as water and/or subcooled liquid. Finally, DEC concluded that the PSV failure probability for cycles two through five would be substantially less than the failure probability on the initial cycle, for reasons as discussed at the conference. Based on the above, DEC concluded that the failure probability of Oconee’s PSVs was approximately one order of magnitude less than that assumed by the NRC in its preliminary estimate. As a result, DEC concluded that the finding should be characterized as Green for all three Oconee units. After considering the information developed during the inspection and the information DEC provided at the conference, the NRC has concluded that the final inspection finding is appropriately characterized as White for all three Oconee units, in the mitigating systems cornerstone. In summary, the NRC concluded that the factors discussed at the conference are not well known with respect to their influence on PSV failure probability. The analytical techniques and risk analysis of DEC’s proposal are novel and unverified with respect to the PSV failure probability following the initial lift. Additionally, DEC did not provide specific testing data to support the conclusion presented at the conference. Absent any additional specific operational, empirical, or testing data, the NRC concluded that the information provided by DEC at the conference was insufficient to warrant a change in the NRC’s preliminary estimate. You have 10 business days from the date of this letter to appeal the staff’s determination of significance for the identified White finding. Such appeals will be considered to have merit only if they meet the criteria given in NRC Inspection Manual Chapter 0609, Attachment 2. The NRC also determined that a violation occurred involving the requirements of 10 CFR 50, Appendix R, Section III.G.3, in that procedures for a fire requiring SSF manning and activation would not assure that the reactor coolant makeup function would be capable of maintaining reactor coolant level within the indicated range of the pressurizer. Accordingly, a Notice of Violation is included as an enclosure to this letter. In accordance with the NRC Enforcement Policy, NUREG-1600, the Notice of Violation is considered escalated enforcement action because it is associated with a White finding. The NRC has concluded that information regarding the reason for the violation, the corrective actions taken to correct the violation and prevent recurrence, and the date when full compliance was achieved is adequately addressed on the docket in the information provided by DEC at the conference (Enclosure 3). Therefore, you are not required to respond to this letter unless the description therein does not accurately reflect your corrective actions or your position. In that case, or if you choose to provide additional information, you should follow the instructions specified in the enclosed Notice. Based on NRC Inspection Manual Chapter 0305 guidance, the performance consideration start date for this issue is the third quarter of 2004 (i.e., when the preliminary significance determination was made known via Inspection Report 05000269,270,287/2004012, dated July 20, 2004). Consequently, as a result of this White finding, plant performance has been determined to be in the Degraded Cornerstone Column for Units 1, 2, and 3, because of a previously identified White finding in the Mitigating Systems Cornerstone (EA-03-145). We will use the NRC Action Matrix to determine the most appropriate NRC response for this finding and will notify you of that determination by separate correspondence. In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter and its enclosures, and your response (should you choose to provide one), will be available electronically for public inspection in the NRC Public Document Room (PDR) or from the NRC’s document system (ADAMS). ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room). For administrative purposes, this letter is issued as a separate NRC Inspection Report, No. 05000269,270,287/2004013, and the above violation is identified as VIO 05000269, 270,287/2004013-01: Failure to Meet Licensing Basis for Staffing the SSF in the Event of a Confirmed Plant Fire. Accordingly, the associated apparent violation, AV 05000269,270, 287/2004012-01, is closed. Should you have any questions regarding this letter, please contact Charles Ogle, Chief, Division of Reactor Safety, Engineering Branch 1, at 404-562-4605.
Docket Nos.: 50-269, 50-270, 50-287 Enclosures: cc w/ encls: Lisa Vaughn Anne Cottingham Beverly Hall, Acting Director Henry J. Porter, Director R. Mike Gandy County Supervisor of Lyle Graber, LIS R. L. Gill, Jr., Manager Peggy Force NOTICE OF VIOLATION
During an NRC inspection completed on February 18, 2004, a violation of NRC requirements was identified. In accordance with the “General Statement of Policy and Procedure for NRC Enforcement Actions,” (Enforcement Policy), the violation is listed below:
This violation is associated with a White Significance Determination Process finding for Units 1, 2 and 3. The NRC has concluded that information regarding the reason for the violation, the corrective actions taken to correct the violation and prevent recurrence and the date when full compliance was achieved is already adequately addressed on the docket in the information provided by Duke Energy Corporation at the conference (Enclosure 3) and in NRC Inspection Report 05000269,270,287/2004012. However, you are required to submit a written statement or explanation pursuant to 10 CFR 2.201 if the description therein does not accurately reflect your corrective actions or your position. In that case, or if you choose to respond, clearly mark your response as a "Reply to a Notice of Violation - EA-04-115," and send it to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, DC 20555 with a copy to the Regional Administrator, Region RII, within 30 days of the date of the letter transmitting this Notice of Violation (Notice). If you contest this enforcement action, you should also provide a copy of your response, with the basis for your denial, to the Director, Office of Enforcement, United States Nuclear Regulatory Commission, Washington, DC 20555-0001. If you choose to respond, your response will be made available electronically for public inspection in the NRC Public Document Room or from the NRC’s document system (ADAMS), to the extent possible, it should not include any personal privacy, proprietary, or safeguards information so that it can be made available to the public without redaction. ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html. If personal privacy or proprietary information is necessary to provide an acceptable response, then please provide a bracketed copy of your response that identifies the information that should be protected and a redacted copy of your response that deletes such information. If you request withholding of such material, you must specifically identify the portions of your response that you seek to have withheld and provide in detail the bases for your claim of withholding (e.g., explain why the disclosure of information will create an unwarranted invasion of personal privacy or provide the information required by 10 CFR 2.390(b) to support a request for withholding confidential commercial or financial information). If safeguards information is necessary to provide an acceptable response, please provide the level of protection described in 10 CFR 73.21. In accordance with 10 CFR 19.11, you may be required to post this Notice within two working days. Dated this 24th day of September 2004 |
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