Type of Facility: Corium


The PREMIX experiments have been performed to study the premixing of sizable amounts of very hot oxidic melts with water when being released as a jet in a reasonably characterized way and with full optical access. Alumina at 2600 K from a thermite reaction was used to simulate the corium melt. A technique has been developed to retain the molten iron in the source so that the contribution of iron to the melt is well below 10 %. PREMIX involves the full physics of the mixing process including jet break-up and melt drop fragmentation. But, of course, on the other hand, the initial and boundary conditions are more difficult to control and to vary compared to experiments with solid spheres such as QUEOS.


The test facility consists of a slender cylinder with an effective inner diameter of 0.66 m bearing plane glass windows in the front and back sides. The upper part is occupied by the melt generator which leaves a 0.14 m wide annular space for the steam flow. The facility is entirely closed except for four large venting pipes (4 m long, each with a cross section of 90 cm2) which were also closed in two tests. The space below the melt generator is about 2.2 m high but for the processes to be studied, the actual height of the test water pool was determined by a concave debris catcher that could be mounted at different heights. The test rig was placed inside a large (220 m3) pressure vessel providing a safety barrier and the possibility to perform tests at elevated ambient pressure.

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