Results of the Triggered Steam Explosions from the TROI Experiment

Triggered steam explosion experiments have been carried out in the TROI facilities to investigate the energetics of the steam explosions. Two types of corium melt were used as a melt. One was eutectic corium at 70:30 wt% (UO₂:ZrO₂), and the other was corium at 80:20 wt%. The diameter of the water pool was 0.6 m, and the depth was varied from 0.67 to 1.3 m. An external trigger (PETN, 1.0 g) was applied just before contact of the melt and the bottom of the interaction vessel, which is believed to be the time of a possible spontaneous triggering. The external trigger led to triggered steam explosions in all the experiments. In the experiments with 70:30 corium, the maximum recorded dynamic pressure and the dynamic load were 17.0 MPa and 360 kN, respectively. Meanwhile, in the experiment with 80:20 corium, the maximum dynamic pressure and the dynamic load reached 7.7 MPa and 200 kN, respectively. The energetics obtained from the triggered steam explosion tests with 70:30 corium were greater than those from the triggered experiment with 80:20 corium. The strength of a triggered steam explosion was found to depend on the composition of the corium.