Development of advanced containment thermal-hydraulic analysis methodology based on three-field model codes for APR1400

Advanced ME (Mass and Energy) release analysis methodology and PT (Pressure and Temperature) analysis methodology were developed using advanced thermal-hydraulic computer codes of three-field model for the Gen-III reactor, APR1400. Both conservative and realistic approaches were harmoniously adopted for the ease of licensing and for economics. Conservative approach was taken for the ambiguous process and phenomena, while realistic approach for the clearly identified process and phenomena. Break separation model was implemented in the ME analysis step for conservatism, and direct spillage was bypassed considering the APR1400 features. Reactor–containment coupling analysis was introduced in ME analysis for realistic analysis. Liquid carryover rate was determined by assessing the typical experiments. For PT analysis several mechanistic models including water surface evaporation and condensation model were developed. And these new models evaluated the conventional models. Unrecovered water modelling was introduced, and realistic component arrangement was modeled. This new ME and PT methodology result in additional design pressure margin of nearly 66 kPa.