[en] Core catchers are employed to protect the containments of water, steam or gas cooled reactors in case of core meltdown. To prevent releases of hydrogenous coolant and of the radiolytic decomposition of water, respectively, the surface of the core catcher is coated with a protective substance. This material may be an oxide or a mixture of several oxides of the MgO, CaO, B₂O₃ and SiO₃ groups. On the other hand, also a compound or a mixture of compounds of the borates, phosphates, chromates and carbonates groups can be used. Silver in addition may be mixed into the protective substance to bind any iodine that may be generated. (orig./PW)