Analysis of loss of cooling and loss of coolant severe accident scenarios in VVER-1000/V446 spent fuel pool

Abstract

The spent fuel storage system is designed to store and cool the spent fuel within several years with account for scheduled refueling and emergency unloading of the entire reactor core. The Fukushima nuclear disaster in 11 March 2011 showed that the safe storage of spent fuel assemblies in the spent fuel pool (SFP) is very vital since many radioactive fission products could be simply released into the environment if a severe accident occurred in this equipment. In this study, severe accident scenarios at the VVER-1000/V446 spent fuel pool are studied using the MELCOR 1.8.6 severe accident analysis code. Since the most likely events of the SFP are the loss of cooling and loss of coolant, scenarios leading to such accidents (i.e. six scenarios for different leakage rate and leak elevation) are modeled and investigated. The most important results of this study are the calculation of the occurrence time of the key events, the amount of generated hydrogen that has great importance in development of hydrogen mitigation strategies, and the amount of radioactive materials released into the containment for each scenario.