Break up time of fragmentating-solidifying UO2 spheres when quenched in sodium

Characterization of high-temperature nuclear fuel-coolant interactions through X-ray visualization and image processing

“…The diminished temperature at the melt-coolant interface is thought to promote rapid solidification of the outer melt surface [15,16,17]. Extreme temperature gradients across a thin outer crust layer, shrinkage cracking of the crust, [18], pressurization of the internal liquid-phase melt [19,20] and the rapid vaporization of entrained coolant [21,22] may all impose mechanical stresses on the melt crust and instigate thermal fragmentation.…”