Transient release of radioactive iodine from the fission of UF4 in 2LiF–BeF2 salt

Abstract

In this study, the behavior of fission product iodine released from the melting process of a mixture consisting of UF₄ irradiated with neutrons and 2LiF–BeF₂ (FLiBe) salt was studied. The experiment showed that a large amount of iodine was released immediately during melting and captured by Ni metal foils. The transient release of iodine observed in this experiment is attributed to the redox reaction between the hot atoms of the fission product iodine that cumulated due to long-time irradiation. The effect of the redox status of the molten salt on the transient release of iodine was also investigated. Based on this investigation, it was proposed that the activity ratios of ¹³¹I to salt-seeking fission products in the fuel salt, as an effective diagnostic criterion, may be used for the surveillance of the redox potential of fuel salts in a molten salt reactor.