EFFECTS OF UO2 ZIRCALOY-4 MOLE RATIOS ON REACTION OF UO2 FUEL WITH MOLTEN ZIRCALOY-4

Dissolution Of UO2 crucibles by molten Zircaloy-4 (Zry) was investigated in the temperature range of 2,223 approximately 2,373 K and for specimens having UO2/Zry mole ratios between 7 and 18.2. The uranium concentration in the Zry melt rapidly increased during initial reaction time and approached saturated values, depending on reaction temperature and UO2/Zry mole ratio. Kinetics of uranium concentration increase in the melt was analyzed based on a-natural convection mass transfer model that takes into account the change of contact surface area/melt volume ratio with reaction time. The saturated uranium concentration in the Zry melt was inversely proportional to the UO2/Zry mole ratio. An empirical correlation of saturated uranium concentration in the Zry melt was obtained as a function Of UO2/Zry mole ratios and reaction temperature. This study of the empirical correlation was intended to estimate maximum UO2 fuel dissolution by molten Zry cladding during severe fuel damage accidents for three different reactor type fuels.