Theoretische Untersuchungen zur Spaltproduktfreisetzung aus dem Core eines Hochtemperaturreaktors bei hypothetischen Coreaufheizungsstörfällen am Beispiel von Cäsium

Abstract

The fission product release out of the core of a high temperature reactor during hypothetical heat up accidents has been investigated. This has been attained on support to a physical model, taking into account the micro- and macro-structures of the pyrolytical and graphitical reactor components as well as renouncing an introduction of effektive diffusion coefficients by the description of the fission products transport through the coated particle layers and the fuel elements and renouncing an assuption of the spontaneously adsorption-desorption equilibrium on the surface of the fuel elements. The solving method and the respective computer codes were also developped. In addition the theoretically calculated and the experimentally determined results regarding the caesium release from single coated particles as well as fuel elements at accident temperatures were compared. Finally the caesium release from the core of the PNP-500 reactor during a heat up accident has been estimated and discussed