Phenomenological Modeling of the Triggering Phase of Small-Scale Steam Explosion Experiments

During the past few years, over 300 small-scale experiments have been performed by Nelson at Sandia National Laboratories, investigating the triggering of steam explosions over a variety of initial conditions. The primary purpose of this paper is to present the results of phenomenological modeling and analyses that may explain the experimental observations. These three major conclusions are suggested by the analysis. Noncondensible gases generated by fuel oxidation appear to be the cause of steam explosion suppression for metallic fuel melts, causing a more stable film between the hot and cold liquids. Suppression of the explosion by high ambient pressure or high water temperature is caused by the initial coolant vapor film becoming more stable inhibiting film collapse. All the above effects appear to be trigger related. Therefore, an explosion can be generated if the trigger magnitude is sufficiently increased.