Simple Point-Kinetics Simulator for Molten-Salt-Fuelled Reactors

Abstract

Molten-salt-fuelled reactors (MSRs) are nuclear fission reactors that use a mixture of fissile material and molten fluoride salts as both fuel and primary coolant. Such reactors, which can operate at low pressure and high temperature, have been initially proposed in the 1950s and have been the subject of renewed interest and investigations in the last decade. In contrast to regular, fixed-fuel reactors the dynamic behavior of MSRs is determined by both the fuel properties and the fact that fuel is constantly flowing in and out of the core, which causes some of the delayed- neutrons to be produced outside the core, thus not contributing to the fission chain. Most of the kinetics codes in current use for power rectors do not have the capability to account for fuel convection (flow). This work presents a newly-developed simple point-kinetics code for simulating MSR transient behaviour while accounting for fuel convection, intended primarily for education and preliminary studies of MSR conceptual designs. The developed code can use either of two approximations: instantaneous full-core mixing or no axial mixing. To demonstrate the code’s capabilities, two MSR-specific transient scenarios are analyzed. Results indicate that the instantaneous full-core mixing approximation predicts slower transients than the no-axial-mixing approximation.