National and international activities to develop risk-informed performance-based safety standards for sodium-cooled fast reactors

Two major activities related to risk-informing safety standards for sodium-cooled fast reactors are described. The first addresses a Generation IV activity to produce safety design criteria that provide limited provisions for using probabilistic risk assessment (PRA) to establish a balanced design with regard to contributions to risk, to avoid "cliff edge effects," and to compare results with risk acceptance criteria where specified. The second activity addresses the development of an American Nuclear Society (ANS) standard (ANS 54.1), which recommends the use of PRAs to risk-inform the design; to develop licensing basis events (including proposed frequency boundaries and acceptance criteria); and to categorize structures, systems, and components. This report describes the process that the standard recommends be followed to accomplish each of these steps.