Planning for Extended Operation - License Renewal Implementation and Life Cycle Management

摘要

Justifying that nuclear plants can be safely and economically operated for up to 20 years of extended operation has become common practice in the United States (US) and is emerging as desirable strategy in many other countries. More than 30% of the US nuclear plant fleet has obtained an extended operating license using the License Renewal Rule (10 CFR Part54). Most of the remaining US plants have applications under review by the Nuclear Regulatory Commission (NRC), in preparation, or have notified the NRC of their intent to submit applications. By most measures, the License Renewal Rule is considered a workable and successful rule. In other countries, rules affecting extended operation are evolving; however, the principal of demonstrating that aging related degradation and time-limited aging issues can be successfully managed by existing or enhanced plant programs / practices appears to be a common theme.Obtaining the extended operating license or permit can be thought of as the first step in a long-term strategic plan for a nuclear power plant. The next steps involve (1) managing and implementing the commitments identified during the license renewal process and (2) optimizing long-term maintenance management plans and resources to achieve optimal plant performance, reliability, safety and value. These steps are commonly referred to as license renewal implementation and life cycle management.There are three, key phases to license renewal implementation: (1) making the physical changes to plant procedures, (2) performing the actual inspections and other actions identified in the License Renewal Application (i.e., the commitments), and (3) interacting with the regulator during an inspection performed prior to the period of extended operation. Operating experience reviews to identify and review aging management issues are also part of the implementation process. Several US utilities are actively engaged in implementation activities and a few expected to be inspected by the NRC this year.Life Cycle Management (LCM) is an integral part of effective long term maintenance planning. The objective is to minimize unplanned capability loss and optimize maintenance programs and capital investments consistent with plant safety and operating strategies / goals. The associated process is particularly effective in pulling together the relevant industry research and operating experience, benchmarking plant-specific and industry maintenance practices and operating experience, recognizing plant-specific vulnerabilities (e.g., lost revenue, consequential functional failure costs / liabilities, regulatory inspection / enforcement), opportunities for improvement, and developing near and long-term alternatives. The alternatives are economically evaluated to determine the resource and capital forecasts and identify alternatives with the lowest cost and highest reliability. The evaluations include net present value (NPV) cost analyses, benefit to cost ratio determinations, and sensitivity and uncertainty analyses. Several US utilities have aggressively applied the life cycle management process to a cross-section of critical / important structures, components and component groupings.The US license renewal implementation and life cycle management processes and experience are discussed in this paper.