Resolution of Generic Safety Issues: Issue 179: Core Performance ( NUREG-0933, Main Report with Supplements 1–34 )
Core design is a fundamental component of plant safety because maintaining fuel integrity is the first principal safety barrier (i.e., fuel cladding, reactor coolant system boundary, or the containment) against serious radioactive releases. Likewise, safety analyses must be properly performed in order to verify, in conjunction with startup tests and normal plant parameter monitoring, that a core reload design is adequate and provide assurance that the reactor can be safely operated. QA activities are important to ensure that proper interfaces are established and that shortcuts are not taken that could degrade safety or quality.
Following a briefing of the EDO on March 29, 1994, NRR developed an action plan to address the review of fuel fabrication, core design, and reload analysis issues; this plan was a proactive approach to improve core performance in operating reactors. The briefing presented by the Reactor Systems Branch (SRXB), Division of Systems Safety and Analysis (DSSA), NRR, covered generic fuel and core performance issues and related evaluations of fuel failures; the Vendor Inspection Branch (VIB), Division of Reactor Inspection and Licensee Performance (DRIL), NRR, also participated in the briefing. Specific actions included in the action plan were: (1) evaluate fuel vendors' QA performance through performance-based inspections that evaluate the reload core design, safety analysis, licensing process, fuel assembly mechanical design, and fuel fabrication activities; (2) evaluate the QA performance of licensees that perform core reload analysis functions; (3) identify, document, and categorize core performance problems and root cause evaluations that will be further evaluated during the inspections, and provide input to licensee evaluations as well as support to regional enforcement actions, as appropriate; and (4) train and coordinate regional support staff participating in these activities; and (5) evaluate the results of these activities for use in formulating generic communications, revisions of regulatory guidance, regional inspection guidance, and other appropriate regulatory actions.
The action plan called for DSSA/NRR to identify one or more licensee inspections in each region to be performed, in coordination with the regional inspectors, to assess licensee performance in reload core analysis oversight and participation. The data acquired through licensee/vendor inspections was to be integrated with information supplied by the regions and other sources and evaluated for generic core performance indicators and industry conformance to existing regulatory requirements. The end product of the overall assessment was to include guidance for resident inspectors and regional staff and draft updates to Inspection Manual Chapters. The action plan identified ten vendor inspections to be performed by multi-disciplined inspection teams led by the Special Inspection Branch (PSIB), DISP/NRR, with contractor technical assistance. This issue was identified in an NRR memorandum1601 to RES in February 1996.
The action plan was intended to improve the NRC's ability to assess safety through inspections of fuel vendors, evaluation of licensees' reload analyses and core performance information, and regional training and interaction. Therefore, it was classified as a Licensing Issue.1731
The staff performed inspections of licensee reload analyses and nuclear fuel vendors ABB/CE, Framatome Cogema Fuels (formerly B&W Fuel Company), GE, Siemens Power Corporation, and Westinghouse. Licensee participation in reload analyses and data acquired during the vendor inspections were evaluated by the staff for generic impact and identification of emerging issues. The vendor and licensee inspections were coordinated with the Regions and training was provided to the regional staff. With the inclusion of the evaluation of licensee/vendor lead test programs for identification of core performance problems in the Program Plan for High Burn-Up Fuel1748 (see Issue 170), all required actions were completed and the issue was closed out.1747