Abstract: This paper will describe work within the American Society of Mechanical Engineers committee responsible for rules for inservice inspection of nuclear power plants. Work is progressing with the objective of producing proposals for risk-informed inspection programs that will be incorporated by the US Nuclear Regulatory Commission into the Federal Regulations Governing the construction and inservice inspection of al domestic commercial power plants. The paper will describe in detail the two primary proposals now under development and review. Both are directed toward enhancing safety while reducing the expense of periodic examination of piping welds. The first proposal provides a sound technical basis for reducing the number of Class 1 piping weld examinations as much as 60 percent while improving or maintaining equivalent safety. This is accomplished by using risk-informed techniques to re-establish the most important areas to examine. The second is a broader approach addressing all piping systems considered to be important under risk-informed assessment techniques. Both proposals are based on recent insights into risk analysis techniques developed within the pressure vessel industry, and both require evaluation of theoretical analysis and inputs of practical experience related to a wide variety of detrimental conditions. These proposals are being supported by pilot programs in a number of operating nuclear power plants. The authors will also attempt to explain the institutional constraints inherent in the process of obtaining regulatory recognition of proposals developed cooperatively by industry and the regulatory agency. !4
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