ABSTRACT
The generation of hydrogen by radiolysis of water or metal-water reactions during an accident within an light water reactors and the resulting possibility of hydrogen explosions are an old concern in reactor safety research. For code validation integral experiments in large-scale test facilities are used, which will be described in the following. The aim of the Heiss Dampf Reaktor (HDR) hydrogen distribution experiments is to cover all H2 transport and mixing phenomena relevant for severe accident conditions, while the former tests in the smaller facilities could only partly meet these requirements. This chapter gives an overview on the relevant phenomena effecting the distribution of hydrogen after its release into the containment volume. Future experiments in the same test facilities; Battelle model containment and HDR, are directed to investigate hydrogen deflagration phenomena in multi-compartment containment geometries and the efficacy of hydrogen mitigation methods in a large scale.
