Implementation of a gas transport model in SAM for modeling molten salt reactors

One advanced molten salt reactor design being pursued in the nuclear energy industry uses fuel directly mixed in the salt-based coolant.The Molten Salt Reactor Experiment performed at Oak Ridge National Laboratory, which was a salt-fueled design, demonstrated that gasses entrained in the salt and dispersed throughout the system can play an important role in managing fission products produced during normal operation (e.g., neutron poisons and noble metals).The System Analysis Module (SAM) is a 1D system analysis code being developed by the Nuclear Energy Advanced Modeling and Simulation (NEAMS) program for modeling advanced reactor designs, including reactors with mixed fuel and coolant designs.To support this effort, a gas transport model has been implemented into SAM to improve understanding and modeling of gas behavior in these systems.The model uses a drift flux approximation to predict gas velocity and models were also added to predict bubble size and interfacial area.In addition to adding the gas model to SAM, the Molten Salt Thermal Database (MSTDB), which is being developed by the US Department of Energy Molten Salt Reactor campaign, has also been integrated into SAM to provide access to thermophysical properties of different types of molten salts.Experimental data of helium bubbles rising in FLiNaK molten salt was used for preliminary model validation, which demonstrates reasonable agreement between the model and data; however, further validation is required.