Effect of molybdenum release on UO/MOX fuel oxidation under severe light water reactor accident conditions

Liu, J.  ; Miwa, Shuhei  ; Karasawa, Hidetoshi; Osaka, Masahiko  

To investigate the Mo release behavior and its influence on the fuel oxidation, the oxidation and evaporation behaviors of Mo powders and their influencing mechanism on the oxygen partial pressure around powders were researched by using a thermogravimetric analysis technique. The results revealed that during Mo oxidation and evaporation, the oxygen partial pressure around powders can be dramatically decreased to ensure the mass balance of oxygen. Under guidance of this finding, the oxygen consumption rate by Mo release and the oxidation rate of nuclear fuel in accident conditions were estimated and compared. It is suggested that Mo release can retard the oxidation progress of fuel.