Cooling passive safety features of Reaktor Daya Eksperimental

A small modular nuclear reactor with passive safety features is one of the best solutions for Indonesian energy security to support the national sustainable development as in National Medium Term Development Plant (RPJMN) 20152019. High safety level which shown by a small radioactive release to the environment on various probable accident is the basic scientific consideration beside the economic. Reaktor Daya Eksperimental (RDE) is a 10MWt small modular nuclear reactor applying pebble bed high temperature reactor design. RDE is dedicated as a basic reference and milestone for Indonesia to become a Nuclear Power Technology Provider in the near future. Cooling passive safety features, the capability of nuclear reactor to maintain its cooling performances only by natural mechanism with no external support, is very important feature to survive even in the severest condition as occur in Fukushima accident. This paper presents the cooling passive safety features of RDE in the severest accident scenario called depressurized loss of forced cooling (DLOFC). In DLOFC, the helium which cooled the core reactor is not available as a combination of circulator shutdown and breaks which occur in the primary system. The safety analysis simulation was performed using PEBBED code including the neutronic and thermal hydraulic solver. The analysis results show that in steady-state equilibrium condition the average and maximum fuel temperature is 511.9 0C and 819 0C. When the DLOFC accident is initiated, the core temperature is increasing. After 8.2 hours, the core reach its maximum temperature at 974.9 0C and then decrease subsequently. The results show the cooling passive mechanism of RDE. Combine with the TRISO-based design of RDE, which able to contain the radioactive isotopes provided the fuel temperature is under the limiting value of 1620 0C, the cooling safety feature ensure the safety design target of RDE that there is no dangerous radioactive release to the workers, populations, and environments even in the severest accident.