The experimental programme named KAJET is being performed to investigate features of a pressurized melt jet and the interaction with substratum material. Compact melt jets, rather than a spray-type melt release, are simulated using iron and aluminium oxide instead of corium. The melt is generated by a thermite reaction. The experiments provide general information about erosion processes and data for the validation of computer codes (or, if possible, simplified correlations) which then are able to transfer the results to reactor conditions.
The KAJET erosion test facility is shown in Fig. 10-1. Total melt masses of up to 300 kg can be provided by various types of melt generators. Driving pressures of up to 2.5 MPa can be established. Melt release occurs downward into a vessel which is 1100 mm in diameter and 1900 mm in height and has at its bottom layers of gravel and sand. The pressure inside the vessel can be raised up to 0.3 MPa. The examined samples consisted of siliceous concrete and borosilicate glass concrete. The schematic (Fig. 10-2) helps to explain how the test was conducted. The time scale begins with the start of ejection. The first melt component to be ejected on sample no 1 was iron. Shortly before the end of iron release, the plate carrier was turned by 90° within one second. During that time, the melt changed to oxide as the component to be ejected on sample no 2.