Enhancement Of Critical Heat Flux In External Reactor Vessel Cooling(ERVC)

Reactor Pressure Vessel(RPV)is known as heart of the nuclear power plant.Even after enough safety measures having different level of safety defence severe accidents can occur,so it is important to have better In-Vessel Retention(IVR)of the molten corium by maintaining the integrity of the lower head of the RPV or in more severe circumstances cooling the molten radioactive material outside the vessel thus minimizing the risk of vessel as well as an overall containment failure.External Reactor Vessel Cooling(ERVC)is an effective strategy to achieve In-Vessel Retention(IVR)of core melt in the Reactor Pressure Vessel(RPV)under severe accident conditions.Flooding the reactor cavity with coolant to submerge the entire RPV allows for the decay heat removal from the molten corium through the vessel wall so that radioactive molten corium could be contained within the reactor vessel.Many researchers reported that higher degree of sub cooling of fluid enhances the Critical Heat Flux(CHF)in ERVC but to achieve higher degree of sub cooling is a question to be answered in ERVC,here in this thesis Lithium Bromide Vapour Absorption Refrigeration System(LiBr VARS)is discussed and designed for ERVC to achieve higher degree of sub cooling.Compared with vapor compression cycle it is a heat driven system and does not uses any compressor which is the main consumer of electricity.In this thesis single effect Vapor Absorption Refrigeration System using H2O as refrigerant and LiBr as an absorbent is designed.LiBr VARS is designed for 24MW capacity which is maximum reported heat load for AP1000 nuclear reactor in case of core meltdown.Heat load for all of its components are calculated and correspondingly fundamental components of the system are designed,then effect of higher degree of sub cooling is checked using ANSYS Fluent,it is noted that higher degree of sub cooling significantly enhances the Critical Heat Flux.