An Approach to Estimate the Compartment Fire Ignition Frequency for HTGR NPP Based on LWR Generic Data

TASK 6 of NUREG/CR-6850 provides the detailed approach on how to estimate the fire frequencies of compartments and scenarios in Fire PRA. The approach is based on the historic data of light water reactor nuclear power plant, and suitable for the operating plants. However, lack of operational experience is an obvious issue for the new type of reactor, e.g. the High Temperature Gas Cooled Reactor (HTGR). We still can use NUREG/CR-6850 as the methodological reference. In this research, key issues for ignition frequency evaluation are discussed firstly, which are arisen during the fire PRA development of the first HTGR nuclear power plant demonstration project in China (HTR-PM). Two methods are developed accordingly to estimate compartment fire frequency for HTGR plant, namely, one is based on plant-level information and the other is based on component-level information. A real and typical compartment of HTR-PM (switchgear room) is subsequently piloted to verify the two proposals.