Modeling of radiative heat transfer during a PWR severe accident

Titre de la revue : Nuclear Technology Volume : 154 N° : 2 Pagination : 194-214 Date de publication : 01/05/2006

The paper is a synthesis of a study on radiative exchanges in Pressurized Water Reactior (PWR) core undergoing a severe accident sequence. This work is based on the hypothesis that the reactor core is an optically thick porous medium, which is justified when comparing the radiation absorption length to the medium dimension. The diffusion approximation is then adopted to treat the radiation transport in the medium which geometry continuously evolves. Then, an homogenization procedure is applied to establish the expression of the radiative conductivity of the system. This conductivity is, in particular, function of the geometry of the system. Thus the rod swelling, the material flow down and the rod and structures collapse into fragments are taken into account.