• Proceedings of the KSME Conference
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• 2003.11a
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• pp.414-419
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• 2003

In the recent TROI experiments, melts of zirconia and two different compositions of corium were used to observe the occurrence of a steam explosion when it came into contact with water at two different depths. The compositions of the corium were 70 : 30 and 80 : 20 in weight percent of $UO_{2}$ and $ZrO_{2}$, and the mass of the corium was about 10kg. The depth of water in the interaction vessel was 67cm and 130cm. A steam explosion did not occur in the interaction between 80 : 20 corium melt and water at 130cm depth, while steam spikes were observed in the interactions between corium melts of two different compositions and water at 67cm depth. A strong steam explosion occurred in the interaction between 5.43kg of zirconia melt and water at 67cm depth. This fact shows that the explosivity of zirconia is much greater than that of corium.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.2041-2046
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• 2004

Recently series of steam explosion experiments have been performed in the TROI facility to identify the influence of corium compositions on the occurrence of a spontaneous steam explosion varying corium melt composition. The compositions of the corium were 0 : 100, 50 : 50, 70 : 30, 80 : 20 and 87 : 13 at weight percent of $UO_2$ to $ZrO_2$, and the mass of the corium was about 10kg. Corium melt at 0 : 100 weight percent (pure zirconia) caused a strong spontaneous steam explosion, and melt at 70 : 30 weight percent(eutectic corium) led to a weak steam spike, while melts at other compositions did not result in spontaneous steam explosions, when they came into contact with 67cm deep water pool at room temperature. It seems that the explosivity of pure zirconia is stronger than that of corium at other compositions and a steam explosion is not likely to occur with corium melts at non-eutectic compositions which are included in mushy zone region.