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EA-03-230 - Waterford 3 (Entergy Operations, Inc.)April 12, 2004 EA-03-230 Joseph E. Venable
Dear Mr. Venable: The purpose of this letter is to provide you the final results of our significance determination of the preliminary "Greater Than Green" finding identified in the subject inspection report. Our preliminary finding was discussed with your staff during an exit briefing conducted on January 5, 2004. The inspection finding was assessed using the Significance Determination Process and was preliminarily characterized as "Greater Than Green" (i.e., an issue of greater than very low safety significance). The finding involved the failure to establish appropriate instructions and accomplish those instructions for installation of a fuel line for the Train A emergency diesel generator in May 2003. The associated performance deficiency resulted in uneven and excessive scoring of the fuel line tubing that ultimately led to a complete 360-degree failure of the fuel supply line on September 29, 2003, during a monthly surveillance test, rendering the Train A emergency diesel generator inoperable. At your request, a Regulatory Conference was held on March 8, 2004, to further discuss your views on this issue. During the meeting, your staff acknowledged the performance deficiency and described your assessment of the risk significance of the finding. In a supplemental response, dated March 15, 2004, you provided additional information regarding your risk evaluation of the event. A copy of your supplemental response is enclosed. A summary of the Regulatory Conference was issued March 16, 2004. During the Regulatory Conference you agreed that the failure to establish appropriate instructions and accomplish those instructions for installation of a fuel oil line for Train A emergency diesel generator in May 2003 was a performance deficiency and a violation of your Technical Specifications. However, you took exception to certain aspects of the NRC's evaluation of risk associated with this event. After considering all of the information available, and for reasons explained below, the NRC has concluded that the finding is appropriately characterized as "White." During the Regulatory Conference, your staff provided an overview of the event and the root cause, described your assessment of the significance of the finding, and provided your regulatory perspectives. We agree with your overall view of the event and the root cause determination. However, we do not agree with the approach that your staff undertook in assessing the safety significance for crediting repair of the Train A emergency diesel generator. With regard to applying credit for repair in this case, the NRC evaluated credit for repair in determining the significance of this performance deficiency. However, the modeling of specific maintenance repair activities in the context of probabilistic risk assessment (PRA) sequences is inherently complex and typically requires detailed analysis with appropriate supporting data. NRC Manual Chapter 0609, "Significance Determination Process," dated March 21, 2003, Regulatory Guide 1.200, "An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities," and the ASME PRA Standard provide guidance for modeling equipment repair. The NRC acknowledges that a fraction of PRA models (including the NRC's SPAR 3i models) credit repair of emergency diesel generators by treating all emergency diesel generator failure modes in the aggregate, irrespective of the failure mechanisms, and establishing a mean or median-time-to-repair (MTTR). In general, these models have MTTR in the range of four to eight hours, which is a significantly longer period of time than that considered in your risk assessment. The analysis that your staff performed for the emergency diesel generator repair at Waterford 3 deviated from the guidance provided in Regulatory Guide 1.200 and is different from the accepted approach for the use of repair, which addresses the spectrum of failure causes and the distribution of repair times for all causes. The NRC accepts that you have demonstrated the feasibility of accomplishing the repair for this particular failure mechanism under a certain set of conditions. However, in order to credit the repair of the emergency diesel generator fuel line rupture in the risk assessment, it is incumbent upon you to demonstrate the feasibility of accomplishing the repair under a reasonably bounding set of conditions. The NRC found your analysis was based on assumptions that did not appropriately consider the dependencies among those actions as well as human error probabilities. The analysis that was performed for the repair did not present sufficient justification for deviating from the guidance provided by Regulatory Guide 1.200. During the Regulatory Conference, your staff noted that NRC had previously allowed consideration of manual actions in performing significance determination assessments and therefore the precedent had been set for allowing credit for repair in this specific instance. In reviewing the supplemental information that you provided following the conference (enclosed), each of the examples that you identified concerned situations where the NRC had allowed the use of manual actions for recovery, not repair. There are different approaches that are used for analyzing recovery and repair actions. Recovery actions lend themselves to human reliability assessment techniques, and are in principle acceptable given certain conditions where procedures exist that address the necessary actions, training has been conducted for the existing procedures under conditions similar to the scenario assumed, and any equipment needed to complete these actions is available and ready to use. The repair situation that you faced was quite different than the situations in which NRC has credited recovery actions. Plant operators and maintenance personnel were not specifically trained to make the repair to the EDG fuel supply line under a reasonably bounding set of conditions, there were no specific repair procedures in place, and there was no pre-staged equipment or tools. Also, Regulatory Guide 1.200 does not provide credit for repair actions in which no actuarial data exists, which is the case in this instance. As a result of non-conservative assumptions in your analysis, including the reasons noted in the preceding discussions, the NRC concluded that you did not make a compelling argument for crediting the repair of the emergency diesel generator in the time assumed in your analysis. As discussed during the Regulatory Conference, the failure of the Train A emergency diesel generator fuel supply line was a stochastic occurrence that occurred after a 2.8-hour run time during a surveillance test. Depending on the operating history of the emergency diesel generator after the performance deficiency occurred, the failure could have occurred in significantly less than 2.8 hours or could have occurred in significantly greater than 2.8 hours. The NRC staff noted that a failure in less than 2.8 hours would have caused a greater increase in the risk estimation than the corresponding decrease in risk estimation associated with a failure following a period of greater than 2.8 hours. We also noted that your analysis did not adequately consider the spectrum of conditions that could occur in a station blackout scenario, some of which may be less conducive to successful timely repair. The NRC staff agrees that there were conservatisms in our safety assessment for the emergency diesel generator run failure rate and the 4-hour battery depletion time. However, we do not agree that we neglected the 2.8-hour Train A emergency diesel generator run time before fuel oil line failure. Notwithstanding that an earlier failure was possible, the initiating event frequency was adjusted to account for the 2.8-hour run time. Overall, the NRC found that these conservatisms were sufficient to change the NRC 's overall safety significance determination from "Yellow" to "White" for the case in which no repair of the Train A emergency diesel generator is credited. Therefore, after considering the information developed during the inspection and the information you provided at the conference, as well as the information provided in your supplemental response, the NRC has concluded that the inspection finding is appropriately characterized as White, (i.e., an issue with low to moderate increased importance to safety, which may require additional NRC inspection). You have 30 calendar 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 violation of the requirements of 10 CFR Part 50, Appendix B, Criterion V, is cited in the attached Notice of Violation (Notice). 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. You are required to respond to this letter and should follow the instructions specified in the enclosed Notice when preparing your response. Because plant performance for this issue has been determined to be in the regulatory response column, we will use the NRC Action Matrix to determine the most appropriate NRC response for this event. We will notify you by separate correspondence, of that determination. In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter and its enclosures will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records (PARS) component of 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).
Docket: 50-382 Enclosures: cc w/Enclosures: Senior Vice President and Vice President, Operations Support Wise, Carter, Child & Caraway General Manager, Plant Operations Manager - Licensing Manager Chairman Director, Nuclear Safety & Michael E. Henry, State Liaison Officer Parish President Winston & Strawn
ENCLOSURE 1 NOTICE OF VIOLATION
During an NRC inspection completed January 5, 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 violation is listed below: 10 CFR Part 50, Appendix B, Criterion V, "Instructions, Procedures, and Drawings," states in part, that activities affecting quality shall be prescribed by documented instructions, procedures, or drawings, of a type appropriate to the circumstances and shall be accomplished in accordance with these instructions, procedures, and drawings. Contrary to this requirement, during the overhaul of Train A emergency diesel generator in May 2003, the licensee failed to establish adequate instructions to ensure proper installation of the fuel supply line of Train A emergency diesel generator. This failure resulted in uneven and excessive scoring of the tubing that ultimately led to a complete 360 degree failure of the fuel supply line on September 29, 2003, during a monthly surveillance test. This violation is associated with a white significance determination process finding. Pursuant to the provisions of 10 CFR 2.201, Entergy Operations, Incorporated is hereby required to submit a written statement or explanation to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, DC 20555 with a copy to the Regional Administrator, Region IV, and a copy to the NRC Resident Inspector at the facility that is the subject of this Notice of Violation (Notice), within 30 days of the date of the letter transmitting this Notice. This reply should be clearly marked as a "Reply to a Notice of Violation" and should include: (1) the reason for the violation, or, if contested, the basis for disputing the violation or severity level, (2) the corrective steps that have been taken and the results achieved, (3) the corrective steps that will be taken to avoid further violations, and (4) 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. Where good cause is shown, consideration will be given to extending the response time. 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. Because your response will be made available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records (PARS) component of 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 (the Public Electronic Reading Room). 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. Dated this 12th day of April 2004 |
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