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 investigat ed in the temperature range of 2,223 approximately 2,373 K and for spe cimens having UO2/Zry mole ratios between 7 and 18.2. The uranium conc entration in the Zry melt rapidly increased during initial reaction ti me 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 mode l that takes into account the change of contact surface area/melt volu me ratio with reaction time. The saturated uranium concentration in th e Zry melt was inversely proportional to the UO2/Zry mole ratio. An em pirical correlation of saturated uranium concentration in the Zry melt was obtained as a function Of UO2/Zry mole ratios and reaction temper ature. This study of the empirical correlation was intended to estimat e maximum UO2 fuel dissolution by molten Zry cladding during severe fu el damage accidents for three different reactor type fuels.