In the event of a hypothetical severe accident in a Light Water Reactor (LWR) it is possible that the core melts and relocates to the lower head of the reactor pressure vessel (RPV). If the severe accident management measures are not successful, the RPV can fail and the core melt is discharged onto the basement of the containment. To prevent a significant release of radioactivity to the environment due to the melt-through of the basement, LWR's might incorporate the ability to retain and cool the core melt on the basement of the containment (core catcher concept). Before the melt arrives on the cooling device on the basement, the melt has to penetrate the reactor cavity. The reactor cavity may be equipped with a metallic plate at its bottom, covered by a layer of sacrificial concrete, to collect the melt over a certain time period. To achieve a complete and homogeneous spreading of the melt over the total area of the cooling device a fast and sufficiently wide melt-through of the metallic plate is required. To investigate the important processes concerning the melt-through of a metallic plate by a simulated core melt, a series of transient KAPOOL experiments has been performed in the years 1998 to 2000. The corium melt in the KAPOOL tests is simulated by an alumina/iron melt, produced by a thermite reaction. Therefore it was possible to investigate the interaction of both parts of the corium melt (metallic and oxidic) with a metal plate. The experiments show that metallic melts in contact with a steel plate that simulates the melt gate between the reactor cavity and the core catcher compartment lead to fast melting of the steel plate (KAPOOL 9). Oxide melts in contact with a steel or an aluminium plate lead to oxide crust formation at the steel or aluminium interface, and subsequent formation of gaps between the crust and the metal plate. In case of a steel plate no ablation of the plate by the oxide melt could be observed (KAPOOL 11 and 12). Due to the lower melting temperature of the aluminium one could detect and analyse failure modes of the plate due to high thermal loadings (KAPOOL 13 and 15 to 17). In addition to the experiments, heat transfer calculations with the HEATINGS code have been performed. The results of the calculations helped to reproduce the experimental results and to identify the important processes concerning the melt-through of a metal plate. A drawback of the KAPOOL tests is the transient character: Volumetric heat production in the melt was not possible to simulate the nuclear decay heat. In the case of real corium melts with decay heat a later thermal erosion of a melt gate made of steel would be expected in contrary to the outcomes of the tests KAPOOL 11 and 12. From the results of the KAPOOL tests 15 to 17 it is advantageous to use aluminium as the material for the bottom of the reactor cavity, as for this material the tests have proved a sufficient fast and large opening of the plate. A very important advantage of using aluminium is the high thermal conductivity of the material, which supports a fast opening of the gate over a large area. When steel should be used as material for the melt gate, further investigations deem necessary to prove a sufficiently large opening of this gate by an oxide melt.