Improvement of the MELCOR condensation heat transfer model for the thermal-hydraulic analysis of a PWR containment

Thermal-hydraulic Safety Assessment of Full-Scale ESBWR Nuclear Reactor Design

The Economic Simplified Boiling Water Reactor (ESBWR) is a boiling water nuclear reactor of Generation III+. The US Nuclear Regulatory Commission (NRC) approved the ESBWR design as the world's best light-water nuclear reactor in 2014. It has the lowest core damage frequency (industry standard indicator of safety) of any Generation III or III+ reactor. It can cool automatically for more than seven days without using electricity or human intervention. During the operation, the ESBWR is designed to produce electricity while emitting almost no greenhouse gases. The energy generated by an ESBWR will prevent the emission of approximately 7.5 million metric tons of CO2 per year compared to standard electricity production on the US grid. The analysis present in this paper aimed to characterize the thermal-hydraulic simulations of full-scale ESBWR design. The analysis presented will help in recognizing the improvement needed in the reactor design and its passive safety systems. The analysis is performed for normal steady state and postulated design basis accident scenarios . The simulation results obtained by the code REALP/SCDAPSIM/MOD3.4 are compared with the TRACG and MELCOR code results to determine the code predictability and accuracy under accident conditions of the newly proposed design of the ESBWR nuclear reactor. It has been also demonstrated that for the postulated accident conditions the design of passive safety systems are capable to capture the accident progression without any active power.