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Regulatory ActivitiesCompleted Based on some further study of the issue, the NRC was concerned about licensees' calculations for the amount of water available to the sump pumps in the case of a loss-of-coolant accident. The NRC issued Generic Letter 97-04, "Assurance of Sufficient Net Positive Suction Head for Emergency Core Cooling and Containment Heat Removal Pumps," asking licensees to provide these calculations for review. No generic concerns were identified during the NRC's review. Events at a number of plants raised concerns regarding the potential for coatings in containment to form debris and clog sump screens and suction strainers. The NRC subsequently issued Generic Letter 98-04, "Potential for Degradation of the Emergency Core Cooling System and the Containment Spray System After a Loss-of-Coolant Accident Because of Construction and Protective Coating Deficiencies and Foreign Material in Containment," to obtain information in order to evaluate how the licensees maintain and monitor these coatings. Also, the NRC revised Regulatory Guide 1.54, "Service Level I, II, and III Protective Coatings Applied to Nuclear Power Plants," to employ current American Society for Testing and Materials standards for the selection, qualification, application, and maintenance of protective coatings. The industry submitted evaluation guidelines for licensees to use when analyzing their plants for sump performance. The NRC reviewed these evaluation guidelines and issued a safety evaluation in December 2004. Ongoing Planned As GSI-191 approaches resolution, the NRC plans to use several approaches to obtaining reasonable assurance that sumps will perform adequately if called upon following a LOCA. The NRC plans to complete a series of plant-specific audits. The staff plans to review each licensee's final supplemental response to GL 2004-02. To support this review and minimize the potential for RAIs, the NRC has developed and released to licensees and other members of the public a content guide for the final supplemental responses. In addition, the Regions are inspecting each PWR to verify that licensees have made changes to which they have committed in correspondence with the NRC. |
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