United States Nuclear Regulatory Commission research program to understand aging and manage its effects in nuclear power plants

Aging affects all reactor structures, systems and components to some degree and has the potential to increase risks to public health and safety if its effects are not controlled. Therefore, in order to ensure continuous safe operation of a nuclear power plant as it advances in age, measures must be taken to monitor key structures, systems, components and interfaces to detect aging degradation and, if necessary, to mitigate it through maintenance, repair or replacement. For an older plant, this could become increasingly difficult as the plant reaches the end of its normal design life (40 years) and continues into extended life. Thus, aging is a key concern for currently operating plants and will clearly be crucial to any assessment of the safety implications of license renewal. The United States Nuclear Regulatory Commission (NRC) Office of Nuclear Regulatory Research has developed a program for Nuclear Plant Aging Research (NPAR). This research program has been initiated to achieve an understanding of nuclear plant aging, its potential effects on safety and methods for its detection and mitigation, sufficient for addressing safety and regulatory issues and supporting regulatory decisions on issues. The paper describes the stressors and environment contributing to aging and degradation processes, the impact and influence of aging on safety and the technical safety issues that will require timely resolution before safety is affected. The paper also discusses the major activities of the NRC sponsored aging research program and recommends an approach to managing aging at nuclear power plants. (author). 19 refs, 1 fig., 5 tabs