Bestimmung einer geometrieabhängigen Kenngröße und Entwicklung eines Rechenmodells zur Beschreibung des Spaltprodukttransports aus kugelförmigen Brennelementen graphitmoderierter gasgekühlter Reaktoren

The fuel elements of High-Temperature Reactors, coated with pyrolitic carbon and covered with graphite, release fission products like all other fuel elements. Because of safety reasons the rate of this release has to be kept low and has also to be predictable. Measured values from irradiation tests and from post-irradiation tests about the actual release of different fission products are present. The physical and chemical mechanism, which determines the release, is extraordinarily complex and in particular not clearly defined. Because of the mentioned reasons a simplified calculation model was developed, which only considers the release-mechanisms phenomenologically. This calculation model coincides very well in its results with values received in experiments till now. lt can be hold as an interim state an the way to a complete theory