Probable Maximum Precipitation Flooding Analysis for Nuclear Power Plant Permitting

Recently, many electric power generation companies have a renewed interest in the development of new generation nuclear power plants. In response to that interest, several Early Site Permit and Combined License applications have been submitted to the Nuclear Regulatory Commission (NRC) seeking permits for new nuclear power plants. The application process requires the submittal of a Safety Analysis Report (SAR) for the site and power plant. The Safety Analysis Report requires probable maximum precipitation (PMP) flooding analysis for adjacent streams and rivers as well as local site drainage. Procedures and guidance from the NRC and others are presented for PMP flooding analysis on river watersheds. The presentation is based on analysis performed for recent applications to the NRC as well as the NRC's independent PMP analyses that were preformed to evaluate the applications. Specific topics addressed are the spatial and temporal development of the PMP for a watershed, runoff analysis and calibration of runoff analysis, flood routing, combined events criteria, water level determination, and NRC independent analysis approach.