During the operation of power reactors the fuel elements are subject to alterations due to fuel burn-up, oxidation of the cladding material, and diffusion of actinide material in the Zr-tubes, which contain the fuel.

Increased oxidation rates of the inner part of the cladding tubes are due to the impact of fission products, and due to the increased temperature. The same holds for the diffusion process where uranium and plutonium are deposited due to sputtering processes on to the inner surface of the tubes, which then mix with the Zr-oxide layer.

Oxidation and diffusion, under reactor conditions are subjects under investigation at the LOHENGRIN spectrometer (PN1).