Kema Scientific and Technical Reports, Volume 8, Number 1. Special Issue:Experiments on the High-Temperature Behaviour of Neutron-Irradiated Uranium Dioxide and Fission Products

摘要

The objective of the study was to determine the release rate of fission productsfrom overheated UO2, the chemical form of these fission products, and the transport mechanisms inside the nuclear fuel. UO2 spheres of approx. 1 mm diameter, irradiated in the High-Flux Reactor at Petten, were used for the experiments. The chemical forms of the particles released from the spheres during evaporation were determined by mass spectrometry and the release rate of the fission products was determined by gamma-spectrometry. It is concluded that the microstructure of the nuclear fuel greatly affects the number of free oxygen atoms, the release rate and the chemical form of the fission products. Finally, a new model is proposed for describing the behavior of oxygen in irradiated nuclear fuel.