Development and validation of a three-dimensional dynamics code for liquid-fueled molten salt reactors

Abstract

BackgroundIn molten salt reactors (MSRs), the liquid fuel salt circulates in the whole primary loop. Part of the delayed neutron precursors (DNP) decay outside the reactor core, but most of the reactor fission power releases directly in the fuel salt. Therefore, the neutronics kinetics (NK) and thermal-hydraulics (TH) are strongly coupled due to the liquid fuel in MSRs, hence traditional dynamic codes cannot be used for MSRs.PurposeThis study aims to develop and validate a three-dimensional time-spatial dynamic code named ThorCORE3D which can be used to carry out design and transient analysis of MSRs.MethodsNodal expand method was used to solve time-dependent neutron diffusion equations and a thermal-hydraulics solver for circulating liquid fuel with internal heat source was developed in ThorCORE3D. Then the code was validated using both steady state and transient experimental benchmark questions of Molten Salt Reactor Experiment (MSRE) of Oak Ridge National Laboratory (ORNL).ResultsThe results show that numerical results from ThorCORE3D are in good agreement with the experiment results and that of other codes. The unique phenomena in MSRs can be well modeled and simulated by the ThorCORE3D.ConclusionsThe ThorCORE3D dynamics code can be used reliably for steady state and transient analyses of liquid fuel MSRs.

Keywords

• molten salt reactor
• coupled neutronics and thermal-hydraulics
• delayed neutron precursors