Simulation of an accident in conditions of cooling system malfunction and ventilation system failure in the spent fuel storage pool of the multipurpose fast research reactor

The paper presents the results of the computational analysis of an accident scenario in the spent fuel storage pool of the multipurpose fast research reactor. The simultaneous failure of the spent fuel cooling system and the ventilation systems is being considered as beyond design basis accident (BDBA) conditions. The computational analysis of the BDBA scenario was performed with the computer program KUPOL-MT designed to simulate thermohydraulic processes in the room atmosphere of the reactor facility containment systems. During the computational analysis with KUPOL-MT, a nodalization scheme for the spent fuel storage pool rooms was developed. The scheduled loading of spent fuel assemblies in the storage pool was considered in the accident simulation, together with the emergency unloading of the entire reactor core. It was shown that the water temperature in the spent fuel storage pool remained below the boiling point and there was no violation of the integrity of fuel cladding for three days after the start of the accident. As the fuel cladding did not collapse, there were no radiation consequences in the considered accident scenario. The calculation results demonstrated insignificant hydrogen stratification in the room above the spent fuel storage pool. It was shown that hydrogen content did not exceed the maximum concentration limit for three days after the start of the BDBA.