Lattice contraction in the rim zone as controlled by recrystallization: Additional evidence

Additional micro X-ray diffraction measurements of the lattice constant are described in the rim zone of a BR3-fuel irradiated under LWR-fuel conditions up to an average burn-up of 68.5 GWd/tM. Though signs of the so-called rim-transformation, with peripheral local burn-up enhancement, porosity increase and Xe-depletion, were found in the fuel, the traditionally accompanying lattice contraction verified in standard high burn-up LWR-fuels, was not detected. The absence of this feature is attributed to the lack of pellet-edge recrystallization in the present case, which likely impeded the release of accumulate strains.