This session will explore the topic of multi-unit (MU) risk for both the existing fleet of light water reactors and advanced reactor designs. Susan Cooper (NRC Office of Nuclear Regulatory Research (RES)) will summarize the integrated site risk approach and results from the NRC’s Level 3 probabilistic risk assessment (PRA) project, including MU Level 1, 2, and 3 results. The Electric Power Research Institute has been involved in developing and applying MU PRA guidance for both U.S. and international nuclear power plants (NPPs). The current approach and status for developing an MU PRA standard will be presented by a member of the Joint Committee on Nuclear Risk Management MU PRA Standard Working Group. Given that some countries outside the United States have many units on a single site, a different perspective on MU risk will be provided by a representative from the international community for which most NPP sites have more than two reactors. Finally, efforts to model MU risk for advanced reactor designs will be summarized by a member from industry.