FIRST-PRINCIPLES STUDY OF TRITIUM BEHAVIOR IN MOLTEN FLiBe

The behavior of tritium in molten FLiBe, including in the presence of He in it, is studied at operating temperatures of MSR. The presence of helium in the fluoride melt is found to insignificantly change the partial function of the tritium-fluorine radial distribution. In the molten salt, preferential binding of tritium to one and two fluorine ions is observed when the bond length between tritium and fluorine is limited by the radius of the first coordination sphere. Tritium is shown to bind more frequently to one fluorine ion at 1073 K, yet this advantage is not apparent in the presence of He, and the tritium coordination changes more frequently. Lower temperatures (T ≤ 973 K) contribute to binding of 3H to two fluorine ions, but the presence of He, which creates an effect of the increasing temperature, can break this trend. Tritium is concluded to very rarely form bonds simultaneously with three fluorine ions. The form of tritium binding by fluorine affects the kinetic characteristics of tritium in molten FLiBe.