Good question - here's a paper and quote on this: "Molten Salt Reactor (MSR) was designed to operate at high temperature in range 700 - 800°C and its fuel is d

Good question - here's a paper and quote on this: "Molten Salt Reactor (MSR) was designed to operate at high temperature in range 700 - 800°C and its fuel is dissolved in a circulating molten fluoride salt mixture. Molten fluoride salts are stable at high temperature, have good heat transfer properties and can dissolve high concentration of actinides and fission product." https://aip.scitation.org/doi/10.1063/1.4972932 https://aip.scitation.org/doi/10.1063/1.4972932