Investigation of RDE thermal parameters during DLOFC in the absence of water inside the Reactor Cavity Cooling System

Abstract

Reaktor Daya Eksperimental (RDE) is a 10MWt small modular of High Temperature Gas-cooled Reactor (HTGR) with passive safety features. This reactor has a Reactor Cavity Cooling System (RCCS) to evacuate heat loss through reactor vessel in operation condition and also the decay heat in the case of accident condition. One of the most important accidents to be considered is the Depresurized Loss Of Forced Cooling (DLOFC) for a long time period. During this accident, the reactor decay heat is evacuated to the cavity cooling system which is supposed in condition of totally loss its cooling water The analysis simulation was performed by solving numerically the two-dimensional equation of heat conduction. The implicit approach was used in the discretization of the equation, Matlab application program was used to execute the simulation program. The simulation was performed in two periods such as 1500 hours calculation to reach the steady state condition in normal operation and 500 hours of DLOFC period. Three conditions to be compared in this analysis: condition with water panel, condition without water panel, and condition without water panel but with high conductivity of concrete. The results show the increasing temperature of core after reactor shut-down until attaint the maximum temperature divers from 1048°C to 1080°C. According to reactor building, the peak temperature of internal concrete wall is 96°C in condition with water panel and rises to 141.6°C in condition without water panel. The temperature can be decreased to 94.3°C in increasing three times the concrete conductivity. In all conditions the reactor core remains safe because the peak temperature is still under the limit of 1600°C. Increasing the concrete conductivity is an alternative means to keep the concrete temperature under the limit of 100°C in accident condition.