Analyses of Material Effects on Steam Explosions in TROI FCI Tests

Heat losses, heat remnants, and solidified layer thickness were calculated using a single-sphere film-boiling model. Debris particles of the quenched TROI (Test for Real cOrium Interaction with water) experiments were the target of analyses. The single-sphere film-boiling model can provide the order of triggerability and exponential potential at fuel-coolant interactions of various melt materials. For the triggerability, a system with a small particle size and large thermal conductivity induces a larger heat loss and a more voided mixture, which means a less triggered system. The explosion potentials are dependent not upon the triggerability but upon the heat contents of the mixture melt particles that can participate in a steam explosion. The calculated solidified layer thickness ratio to the radius of the melt particle, defined as a fragility factor of a melt particle in this paper, also maintained consistency with the order of triggerability and was evaluated by the heat loss. The breakup sizes for various melt materials were analyzed with several types of breakup models. A dynamic breakup model to deal with transient velocities can explain the different breakup sizes of various melt materials.