Knudsen Cell-Mass Spectroscopic Studies on the Relationship between Molybdenum Oxidation and Iodine Volatility in CANDU Fueld

Abstract

High-temperature Knudsen cell-mass spectroscopic experiments were carried out to determine the relationship between molybdenum oxidation and iodine volatility in CANDU® fuel. The results show that the iodine volatility is similar in systems consisting of CsI alone, CsI/UO₂, and CsI/UO₂/MoO_x (with molybdenum in oxidation states 0, 2 and 4). The iodine volatility is much higher, however, in the CsI/UO₂/MoO₃ system (i.e., with molybdenum in oxidation state = 6). The results suggest that the iodine volatility in fuel increases significantly if the oxidation of the molybdenum goes beyond the MoO₂ stage.