Tritium Transport Characteristics Analysis in Molten Salt Reactor Under Transient Conditions

Tritium control is one of the most critical issues for the development of Molten Salt Reactor (MSR). The point kinetic model has been added into the TAPAS (Tritium trAnsPort chAracteristicS code) to research the dynamic responses of tritium transport characteristics during transients. Two typical transient accident conditions for Transportable Fluoride-salt-cooled High-temperature Reactor (TFHR) are simulated, including unprotected reactivity insertion (URIA) and unprotected overcooling (UOC). The distributions of the key variables in the primary loop and variations with time are obtained including TF, T₂ and Cr²⁺. Numerical results show that during transients, tritium has quite different transport characteristics compared with steady state, ranging from tritium production and speciation, absorption by graphite, Cr corrosion and deposition to tritium permeation. The results are discussed in comparison with earlier findings in detail. This study may provide a valuable reference for the tritium control in MSR.