Progress in Adapting Reactor Accidents Physical Models

The diversity in the design of nuclear reactors corroborated with the complexity of the accident scenarios imposes a specific and detailed approach of the evolution of postulated accidents. Standards in this area require the analysis of plant behavior during severe accidents, as an extent of knowledge necessary in case of low probability events. This work is dedicated mainly to the in-vessel degradation of a nuclear reactor core and to what needs to be done when adapting physical models, passing from a vertical fuel geometry to a horizontal one. It is addressed to professionals in the field of severe accidents at nuclear power plants, or to anyone trying to gain some understanding in this subject.