Recent progress in investigations of high burn-up fuel at ITU Karlsruhe in relation to the irradiation IFA-601

In this presentation, recent progress in experimental techniques at the Institute for Transuranium Elements in Karlsruhe is described. This includes sophisticated techniques for high temperature physics measurements, e.g. laser flash experiments up to and above the melting point, yielding both thermal diffusivity and heat capacity, and Knudsen cell effusion studies, again up to the melting point. These apparatus are located in lead-shielded cells thus enlarging the experimental possibilities of the hot cells. In addition, irradiation of UO2 with fission products of fission energy obtained from accelerators are performed yielding information on mechanisms such as polygonization (grain subdivision or formation of the RIM structure), fission gas bubble formation, fission gas resolution etc. These and other techniques are presently applied to the fuel of the irradiation experiment IFA 601-1. The state of this work is summarized separately in a presentation given by T. Sonoda (CRIEPI, Tokyo, and ITU) (author) (ml)