Nuclear Regulatory Commission June 28, 2019 – Federal Register Recent Federal Regulation Documents

The U.S. Nuclear Regulatory Commission (NRC) is issuing for public comment a draft NUREG entitled, ``Refining and Characterizing Heat Release Rates from Electrical Enclosures during FireVolume 2: Fire Modeling Guidance for Electrical Cabinets, Electric Motors, Indoor Dry Transformers, and the Main Control Board'' (NUREG-2178 Volume 2/ EPRI 3002016052). This report is a joint product of the NRC and the Electric Power Research Institute (EPRI) collaborating under a memorandum of understanding for fire research. This report describes improved methods that can increase the realism in the modeling of selected ignition sources. The areas further investigated include the treatment of flame radiation and obstructed radiation, fire propagation between adjacent electrical cabinets, heat release rates (HRRs) for electric motors and dry transformers, fire location factor, non- suppression probability floor values, and the modeling of the main control board.