Design of the Natural Circulation Loop and Implementation of DOWTHERM A Properties into MARS-LMR Code

Molten Salt Reactor (MSR), which is one of the generation IV reactors, has an advantage in these requirements. MSR uses a molten salt mixture as the primary coolant, or the fuel itself and it operates on high temperature, so it doesn't need pressurizing. Also, liquid state fuel has an advantage for pyro-processing with easy separation of fission products. These fission products also have relatively short half-lives compared to those of the existing reactors. With these characteristics, MSR can have inherent safety in both direct and indirect sides. Also, MSR can operate at high temperature range, so that it can have the high efficiency to produce electricity. Therefore, research of MSR is meaningful for developing advanced nuclear reactors. FLiBe which is a mixture of lithium fluoride (LiF) and beryllium fluoride (BeF₂) is used as a primary coolant in MSR and LMR (Liquid Metal cooled Reactor). It has superiority over conventional liquid metal coolant like sodium, because it doesn't react with air or water. thermos-physical properties of DOWTHERM A for MARS-LMR code were made by modifying stg file of existing one. It was based on the process of Moore using 6 output parameters such as specific volume, internal energy, thermal expansion coefficient, isothermal compressibility, specific heat and entropy. With generated stg file (stgdowa.f90) and input file, tpf file (tpfdowa) which includes fluid property tables for MARS-LMR simulation was obtained. For the verification, this tpf file with execution file will be applied to the input deck of our natural circulation design. This work will contribute to researching and developing of MSR and LMR