Design of a natural circulation loop for molten salt coolant studies

With an increasing interest in small modular reactors and molten salt based coolant systems, there is an increasing need for the development of experimental facilities at Universities for training the next generation of nuclear workers. One of the fundamentals of most of the molten salt reactors will be a natural circulation mode which suggests this as a key experimental facility for students to use. With the selection of FLiNaK as the salt, the design of the loop will consider materials, heating, cooling and power requirements. However, the design is not so straight forward from the safety perspective where Fluorine handling now plays a significant role. Sampling of the salt for consideration of measuring chemistry parameters becomes challenging due to the temperatures involved. The paper will describe the design of the loop, reasons behind choices of coolants, materials, and options considered for addressing safe operation of the loop.