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EA-04-018 - Oconee 1, 2, 3 (Duke Energy Corporation)April 8, 2004 EA-04-018 Duke Energy Corporation
Dear Mr. Jones: This refers to the inspection completed on January 21, 2004, involving an issue at your Oconee Nuclear Station. The issue involved Duke Energy Corporation's (DEC) revision to the Oconee Updated Final Safety Analysis Report (UFSAR) for the High Energy Line Break (HELB) analysis in May 2001. The results of the inspection, including the identification of an apparent violation of 10 CFR 50.59, were discussed with your staff on January 27, 2004, and were forwarded to you by letter dated January 29, 2004. Based on the results of the inspection, a pre-decisional enforcement conference was held on March 2, 2004, in the NRC's Region II Office in Atlanta, Georgia, with you and members of your staff to discuss the apparent violation, its significance, root causes, and your corrective actions. A listing of conference attendees, material presented by the NRC, and material presented by DEC are included as Enclosures 2, 3, and 4, respectively. Based on the information developed during the inspection, and the information presented at the conference, the NRC has determined that a violation of NRC requirements occurred. The violation is cited in the enclosed Notice of Violation (Notice), and the circumstances surrounding it are described in detail in the subject inspection report. The violation involves a failure to adhere to the requirements of 10 CFR 50.59, in that DEC made changes to the Oconee facility as described in Section 3.6.1.3 of the UFSAR and referenced analyses that involved unreviewed safety questions (USQs) without obtaining prior NRC approval. In this case, DEC revised an analysis for HELB accidents, which permitted the facility to initiate emergency feedwater (EFW) up to 30 minutes after a HELB accident, instead of 15 minutes as was discussed in the UFSAR and associated reference documents. In addition, the revised analysis permitted the facility to initiate high pressure injection (HPI) up to eight hours after a HELB, instead of one hour. DEC concluded that the May 2001 changes did not require prior NRC review and approval, but that its 10 CFR 50.59 evaluation of May 2001 of the changes was not thoroughly documented. The NRC determined that DEC's review of the UFSAR changes did not adequately consider the impact to plant safety and, therefore, involved performance issues beyond poor documentation of the review that resulted in USQs, as discussed below. The NRC's conclusion that DEC's May 2001 change to the facility involved USQs is based on our review of two particular areas. The first area involves EFW and HPI initiation changes that necessitated the use of the boiler condenser mode (BCM) for cooling the reactor core. DEC stated at the conference that BCM is an approved methodology, and always has been a part of the expected plant response to a small break loss of coolant accident (SBLOCA). In addition, DEC stated that BCM was formally reviewed by the NRC as part of the SBLOCA analysis. The NRC concluded that the use of BCM for an extended time and under the potential accident scenario of a HELB is a USQ because it creates the possibility of an accident of a different type than any evaluated previously in the UFSAR. The delay in the initiation of EFW would allow the scenario to evolve into a HELB with significant RCS volume loss with some limited SBLOCA characteristics and no immediate safety pump injection. In addition, the initiation of EFW for up to 30 minutes after a HELB, and the initiation of HPI into the RCS up to eight hours after the HELB, would necessitate the use of BCM for RCS cooling for up to eight hours to preclude core damage. The use of BCM mode for this extended time has not been reviewed or approved by the NRC for the Oconee facility. BCM may introduce reactivity concerns, which introduces the possibility of an accident of a different type than any evaluated previously in the UFSAR. DEC stated at the conference that the RELAP5 computer code was used to model the response of the system because the RCS is responding in a similar fashion to a SBLOCA due to significant inventory loss and RCS voiding. This significant loss of inventory resulted from an increased number of pressurizer safety relief valve (PSV) lifts in combination with reactor coolant pump leakage. Additionally, DEC stated that the increased degree of voiding within the RCS necessitated a change from the original code of record to RELAP5. While the use of RELAP5 may be appropriate for the modeling of SBLOCA events, the degree with which conditions within the RCS deviated from the original analysis is an indication of the possibility of an accident of a new and different type than evaluated previously in the UFSAR. For these reasons, the NRC concluded that a USQ exists, thereby requiring NRC review and approval prior to DEC's implementation of the facility change. The second area in which the NRC concluded that DEC's May 2001 change resulted in a USQ involved the increased cycling of the pressurizer safety valves (PSV). Because of the facility change to allow EFW initiation within 30 minutes after a HELB, additional PSV cycling would occur. At the conference, DEC stated that the Oconee UFSAR does not assume failures of the PSVs to close, and that a small number of additional valve operation cycles during the subject HELB event would appear to be an insignificant factor regarding PSV qualification. DEC provided substantive information during the conference from the valve's vendor, the results of its own review of the EPRI test data, and information on the actual configuration/operating conditions of the PSVs, to conclude that the small number of additional valve cycles during the analyzed event would have a minimal impact. DEC also contended that there would not be a decreased reliability of the PSVs to close due to the increased number of cycles, citing the EPRI test data and other information provided by the vendor where other model safety valves were cycled numerous times without a failure to reseat. Furthermore, DEC stated that the NRC's USQ concern regarding the additional cycling of the PSVs represented a change in regulatory position. The NRC concluded that, because the May 2001 change would result in increased cycling of the PSVs under steam and liquid conditions, this condition represented a USQ due to an increase in the probability of malfunction of equipment important to safety that was previously evaluated in the UFSAR. Notwithstanding the information provided by DEC at the conference, the EPRI test data for water conditions represented four actuations of a single valve which is not considered sufficient to demonstrate valve reliability under the revised HELB event. The additional vendor test data presented by DEC was not representative of the Oconee model PSV for liquid discharge conditions. The NRC did not agree that the limited available test data would support the conclusion that the increased number of cycles at Oconee would have little affect on the PSV's reliability and ability to perform additional operational cycles. Because of the increased reliance on the PSV to perform multiple cycles under both steam and liquid conditions, the NRC contends that there is a more than minimal increase in the probability that the PSVs will not reclose. Furthermore, the NRC concludes that when any component, be it a safety valve or some other component, has an associated probability of failure per challenge, multiple challenges would result in a greater cumulative probability of failure. With a greater cumulative probability of failure of one or more of the PSVs to close, there is an associated increase in the core damage frequency. In support of its contention that the additional cycling of the PSVs represented a change in the NRC's regulatory position, DEC stated that the PSVs have been determined to be qualified for the HELB event because the NRC closed TMI action item II.D.1 of NUREG-0737 in a safety evaluation to the licensee dated July 1989. DEC based this position on the similarity between the high temperature water discharge expected during the HELB event and other scenarios addressed in the NRC safety evaluation. However, an examination of the NRC safety evaluation reveals that the PSV discharge events reviewed in the July 1989 safety evaluation were those considered to be applicable at that time. These events included UFSAR transients (all of which result in discharge of steam only), extended HPI events (which include breaks in the feedwater system which could result in liquid discharge), and low temperature over pressurization events. The HELB event of interest here is significantly different from those evaluated for item II.D.1 in that for this feedwater line break scenario, there is no prompt, automatic safety system initiated EFW or HPI to maintain system pressure or to provide core cooling during the period of PSV discharge. For all the events evaluated for item II.D.1, core cooling is assured, even if one or more of the PSVs remain in the open position, which is significantly unlike the HELB event of interest where a stuck open PSV directly results in core damage. The staff believes that this consideration alone results in a conclusion that the revised HELB event of interest is a new or different scenario from any previously evaluated by the NRC regarding operation of the PSVs. Therefore, the staff does not believe that its concerns regarding use of the PSVs for the HELB event at issue represent a change in regulatory position, as the licensee contends. In accordance with the "General Statement of Policy and Procedures for NRC Enforcement Actions" (Enforcement Policy), NUREG-1600, the NRC's evaluation of the safety significance of the violation is based on risk insights. At the conference, DEC presented the results of its risk assessment of the 10 CFR 50.59 change, including key inputs and assumptions. DEC estimated that the actual change in core damage frequency as a result of the May 2001 change was of minimal safety significance. The NRC closely considered DEC's risk assessment of the May 2001 change, and found that this assessment did not evaluate the ramifications of a 30 minute delay in restoring secondary side heat removal following this particular HELB on core damage frequency. Instead, DEC presented the ramifications of training changes made under the authority of the safety evaluation in question. Therefore, this risk assessment only involved a 15 to 22 minute delay, depending upon the system used, in restoring secondary side heat removal following this particular HELB on core damage frequency. However, because the May 2001 change represented a change to the licensing basis under 10 CFR 50.59 and was not a performance deficiency, the NRC is of the view that the maximum times (30 minutes for EFW reestablishment, eight hours for HPI reestablishment), are the appropriate inputs to use for the risk estimate. Based on our consideration of the above and other unquantifiable factors that would increase the risk estimate (i.e., the potential for recriticality, the increased likelihood of steam generator tube failure due to the delayed onset of EFW), the NRC concluded that this violation is, at a minimum, of low to moderate safety significance. Therefore, the NRC concludes that this violation should be characterized at Severity Level III in accordance with the Enforcement Policy. Because the 10 CFR 50.59 rule was amended in December 2000 (becoming effective for Oconee on July 2, 2001), the NRC also considered whether DEC's May 2001 changes would have constituted a violation of the amended 10 CFR 50.59 requirement. In this case, the NRC concluded that the changes would create the possibility for an accident of a different type or a malfunction with a different result than any previously evaluated in the UFSAR, and would result in a more than minimal increase in the likelihood of occurrence and in the consequences of a malfunction of the PSVs. As such, the NRC concluded that DEC's changes of May 2001 also would have represented a violation of the current 10 CFR 50.59 requirements. In accordance with the Enforcement Policy, a base civil penalty in the amount of $60,000 is considered for a Severity Level III violation. Because your facility has not been the subject of escalated enforcement actions within the last 2 years, the NRC considered whether credit was warranted for Corrective Action in accordance with the civil penalty assessment process in Section VI.C.2 of the Enforcement Policy. As stated at the conference, DEC's corrective actions included rewriting the May 2001, 10 CFR 50.59 evaluation to address issues that DEC considered to be documentation matters and the conducting a root cause investigation. DEC indicated that its root cause investigation was still in progress at the time of the conference. Based on our review, DEC failed to take sufficient corrective actions to restore the facility to compliance with the requirements of 10 CFR 50.59, failed to identify the root cause of the violation, and failed to take adequate corrective actions to prevent recurrence of the violation. Specifically, DEC neither submitted the May 2001 facility change to the NRC for review and approval, nor returned the facility to the conditions specified in the UFSAR prior to the May 2001 facility change. The NRC would have given consideration to certain interim corrective actions taken by DEC while the acceptability of the facility change was under NRC review; however, DEC failed to offer any such interim measures for NRC consideration. As such, DEC offered no viable corrective actions to restore compliance for this violation. At the conference, DEC concluded only that the violation was due to a lack of documented detail in its original 10 CFR 50.59 evaluation of May 2001. Although the NRC agrees with DEC that the original 10 CFR 50.59 evaluation was not sufficiently documented, the NRC also believes that the review itself was not detailed and lacked thoroughness in certain areas. The NRC concluded that DEC's failure to recognize that the May 2001 changes represent USQs, even as of the date of the enforcement conference, is indicative of a fundamental lack of understanding of the 10 CFR 50.59 process. This lack of understanding appears to have contributed to the licensee's failure to address the noncompliance or to implement corrective actions to prevent recurrence of future violations of 10 CFR 50.59. Based on the above, the NRC concluded that credit was not warranted for the factor of Corrective Action. Therefore, to emphasize the importance of compliance with the regulatory requirements which govern making changes to the facility, and the importance of prompt and comprehensive correction of violations, I have been authorized, after consultation with the Director, Office of Enforcement, to issue the enclosed Notice of Violation and Proposed Imposition of Civil Penalty in the base amount of $60,000 for the Severity Level III violation. After the pre-decisional enforcement conference, it became apparent that appropriate corrective actions had not been taken to restore the facility to compliance with the requirements of 10 CFR 50.59. We initiated discussions with your staff on March 23, 2004, to emphasize the need to return the facility to compliance with regulatory requirements. Although you expressed your disagreement with the NRC's conclusions that this issue represented a violation of 10 CFR 50.59 and that the facility was in non-compliance, you indicated that this issue would be entered into your corrective action program such that compensatory measures and/or corrective actions would be considered. You are required to respond to this letter and should follow the instructions specified in the enclosed Notice when preparing your response. The NRC will use your response, in part, to determine whether further enforcement action is necessary to ensure compliance with regulatory requirements. In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter, its enclosures, and your response will be made available electronically for public inspection in the NRC Public Document Room or from the NRC's document system (ADAMS), which is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html. To the extent possible, the response should not include any personal privacy, proprietary, classified, or safeguards information so that it can be made available to the Public without redaction. The NRC also includes significant enforcement actions on its Web site at www.nrc.gov; select What We Do, Enforcement, then Significant Enforcement Actions.
Docket Nos. 50-269, 50-270, 50-287 Enclosures:1. Notice of Violation cc w/encls: L. E. Nickolson Lisa Vaughn Anne Cottingham Beverly Hall, Acting Director Henry J. Porter, Director R. Mike Gandy County Supervisor of Lyle Graber, LIS M. T. Cash, Manager Peggy Force
NOTICE
OF VIOLATION
During an NRC inspection completed on January 21, 2004, a violation of NRC requirements was identified. In accordance with the "General Statement of Policy and Procedure for NRC Enforcement Actions," NUREG-1600, the NRC proposes to impose a civil penalty pursuant to Section 234 of the Atomic Energy Act of 1954, as amended (Act), 42 U.S.C. 2282, and 10 CFR 2.205. The particular violation and associated civil penalty is set forth below: 10 CFR 50.59 (a)(1) (1999 edition) states in part, that the licensee may make changes in the facility as described in the safety analysis report without prior Commission approval, provided the proposed change does not involve an unresolved safety question. 10 CFR 50.59 (a)(2) states, in part, that a proposed change involves an unresolved safety question if the probability of occurrence or the consequences of a malfunction of equipment important to safety previously evaluated in the safety analysis report may be increased or if the possibility of an accident or malfunction different from any previously evaluated accident or malfunction may be created. Oconee Nuclear Station Updated Final Safety Analysis Report, Section 3.6.1.3, states that the analysis of effects resulting from postulated piping breaks outside containment is contained in Duke Power MDS Report No. OS-73.2, dated July 16, 1973 including supplement 2, dated March 12, 1974. Duke Power MDS Report No. OS-73.2 and supplement 2 credited secondary side cooling within 15 minutes of a high energy line break (HELB) and reactor coolant system makeup from high pressure injection (HPI) within one hour of an HELB. Contrary to the above, on May 17, 2001, the licensee made a change to the facility, as described in the Updated Final Safety Analysis Report, Section 3.6.1.3, and referenced analyses, that involved unreviewed safety questions without obtaining prior NRC approval. Specifically, the Duke Power MDS Report No. OS-73.2 and supplement calculation OSC-7299 were revised to increase the maximum initiation time of Emergency Feedwater following a HELB from 15 to 30 minutes and of HPI from one hour to eight hours. These changes resulted in an increase in the probability of occurrence or the consequences of a malfunction of equipment important to safety, and created the possibility of an accident or malfunction different from any previously evaluated. This
is a Severity Level III Violation (Supplement I). Pursuant to the provisions of 10 CFR 2.201, Duke Energy Corporation is hereby required to submit a written statement or explanation to the Director, Office of Enforcement, U.S. Nuclear Regulatory Commission, within 30 days of the date of this Notice of Violation and Proposed Imposition of Civil Penalty (Notice). This reply should be clearly marked as a "Reply to a Notice of Violation; EA-04-018" and should include: (1) admission or denial of the alleged violation, (2) the reasons for the violation if admitted, and if denied, the reasons why, (3) the corrective steps that have been taken and the results achieved, (4) the corrective steps that will be taken to avoid further violations, and (5) the date when full compliance will be achieved. Your response may reference or include previously docketed correspondence, if the correspondence adequately addresses the required response. If an adequate reply is not received within the time specified in this Notice, an order or a Demand for Information may be issued as to why the license should not be modified, suspended, or revoked or why such other action as may be proper should not be taken. Consideration may be given to extending the response time for good cause shown. Within the same time as provided for the response required above under 10 CFR 2.201, the Licensee may pay the civil penalty proposed above in accordance with NUREG/BR-0254 and by submitting to the Director, Office of Enforcement, U.S. Nuclear Regulatory Commission, a statement indicating when and by what method payment was made, or may protest imposition of the civil penalty in whole or in part, by a written answer addressed to the Director, Office of Enforcement, U.S. Nuclear Regulatory Commission. Should the Licensee fail to answer within 30 days of the date of this Notice of Violation and Proposed Imposition of Civil Penalty, an order imposing the civil penalty will be issued. Should the Licensee elect to file an answer in accordance with 10 CFR 2.205 protesting the civil penalty, in whole or in part, such answer should be clearly marked as an "Answer to a Notice of Violation" and may: (1) deny the violation listed in this Notice, in whole or in part, (2) demonstrate extenuating circumstances, (3) show error in this Notice, or (4) show other reasons why the penalty should not be imposed. In addition to protesting the civil penalty in whole or in part, such answer may request remission or mitigation of the penalty. In requesting mitigation of the proposed penalty(ies), the factors addressed in Section VI.C.2 of the Enforcement Policy should be addressed. Any written answer in accordance with 10 CFR 2.205 should be set forth separately from the statement or explanation in reply pursuant to 10 CFR 2.201, but may incorporate parts of the 10 CFR 2.201 reply by specific reference (e.g., citing page and paragraph numbers) to avoid repetition. The attention of the Licensee is directed to the other provisions of 10 CFR 2.205, regarding the procedure for imposing a civil penalty. Upon failure to pay any civil penalty due which subsequently has been determined in accordance with the applicable provisions of 10 CFR 2.205, this matter may be referred to the Attorney General, and the penalty, unless compromised, remitted, or mitigated, may be collected by civil action pursuant to Section 234c of the Act, 42 U.S.C. 2282c. The response noted above (Reply to Notice of Violation, statement as to payment of civil penalty, and Answer to a Notice of Violation) should be addressed to: Frank Congel, Director, Office of Enforcement, U.S. Nuclear Regulatory Commission, One White Flint North, 11555 Rockville Pike, Rockville, MD 20852-2738, with a copy to the Regional Administrator, U.S. Nuclear Regulatory Commission, Region II, and a copy to the NRC Resident Inspector at the facility that is the subject of this Notice. Because 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 8th day of April 2004 |
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