抄録
The suppression measures of steam explosions are essential for the integrity of a containment vessel in light water reactors during severe accidents. Polyethylene glycol (PEG) can potentially suppress steam explosions when a molten metal falls into a PEG aqueous solution pool. We also reported that PEG is a reliable additive to suppress spontaneous steam explosions with and without external triggers. Water with a PEG becomes cloudy when the solution temperature exceeds a specific limit, known as the cloud point. The dissolved PEG starts precipitating beyond the cloud point temperature. Such precipitates stabilize a vapor film around a high-temperature molten metal and prevent the fine mixing of molten metal in the solution. To evaluate the suppressive effect of PEG solution and the controllability of steam explosion, a small-scale experiment was conducted in which a prototypic reactor metal was melted and released into a solution pool. Type-304 stainless steel and 30 wt% Zr mixed with type-304 stainless steel were used as test metals. The test metal was melted by induction heating in a crucible and kept at 1700°C. The molten metal jet was immersed in a solution pool of 20°C. Visual observation of the interaction between the molten metal and solution shows the effectiveness of steam explosion retardant and the required PEG solution concentration for a molecular weight of 4 million grams per mol.
