Risk-Informed Safety Strategy and Fault Evaluation for the GE Hitachi BWRX-300 Advanced Reactor

GE-Hitachi is in the design stage of a small, simplified Boiling Water Reactor (BWR), named BWRX 300 (˜300 MWe). The design is the latest iteration in GE's history of BWR development and introduces unique design features to address many significant risk contributors associated with the operating fleet of BWRs. The BWRX-300 generally employs a passive approach to reaching a safe-and-stable state in response to initiating events. This is achieved, in part, through isolation of the Reactor Pressure Vessel (RPV) from attached piping using valves directly connected to the RPV. Additionally, a robust, fail-safe Isolation Condenser System (ICS) activates to provide passive cooling to the reactor without any need for inventory makeup or active decay heat removal. This design addresses several major sources of risk-significant sequences traditionally analysed for BWRs: losses of power and loss of coolant accidents, by greatly reducing the frequency of classically important sequences to BWRs and therefore the overall plant risk.