Analysis On The Self-stabilization For A Molten Salt Reactor

The molten salt reactor is the only liquid-fuel reactor of the six Generation IV advanced nuclearenergy systems, which is characterized by remarkable advantages in safety, economics, continuabledevelopment of the fissile resources, and proliferation resistance of nuclear energy. The liquid moltensalt serves as the fuel and coolant simultaneously and causes one important feature: the delayedneutron precursors are drifted by the fuel flow, which leads the spread of delayed neutrons’distribution to noncore parts of the primary circuit, and it also results in reactivity variation dependingon the flow condition of the fuel salt. Therefore, the neutronic and thermal-hydraulic characteristics ofthe molten salt reactor are quite different from the conventional nuclear reactors using solid fissilematerials. Besides, there is no other reactor design theory and safety analysis methodologies can beused for reference.The developed multi-physics modelling approach is implemented in the unified simulationenvironment offered by COMSOL Multiphysics, and is applied to study the behaviour of the systemin steady-state conditions.Then, a model of point-reactor neutron kinetics equation in combinationwith2-D kinetics equations is presented for describing the stability in the molten salt reactor. In thesteady-state operation conditions, dynamic response process of core temperature under the fuelnegative feedback effect was simulated after introducing three step representation disturbances. Thesimulation results indicat that the core could quickly achieve stability under the negative feedbackeffect of temperature. Moreover, the flow characteristics of the fuel salt and the space effect ofdelayed neutron precursors were taken into consideration in this model, which was closer to thereality of the molten salt reactor core.