Das Projekt "Fuel behaviour under accident contitions, 1988-1991" wird vom Umweltbundesamt gefördert und von European Commission, Joint Research Centre (JRC). Institute for Transuranium Elements (ITU) durchgeführt. Objective: To contribute to the understanding of severe accident mechanisms by providing support to code development work (European Accident Code), by specifying and characterising fission products liable to be released from fuel in a particular accident scenario (source term), and by developing and applying specialized instrumentation for in-pile experimentation in the context of studies on post accident heat removal (PAHR). General Information: Progress to end 1990. Two specimens which had been ramp-tested in the SILENE reactor underwent post-irradiation examination at the Institute. In a joint investigation with Ispra, the interaction of molten UO2 with zircaloy was studied . - The Institute has participated in the development of the European Accident Code (EAC) for fast reactors, and the TRANSURANUS code has been incorporated into EAC. Development work for ultrasonic in-pile thermometers for PHEBUS got under way. Equipment for quantitative release measurements of fission products from high burn-up fuel was set up. - Cooperation with EAC lead to 2 joint publications with Ispra. Detailed description of work foreseen in 1991 (expected results). The work programme for PHEBUS PF has not yet been firmly established, but it is expected that the Institute will participate in the Project by furnishing ultrasonic thermometers for in-pile fuel temperature measurements and by performing fuel rod post irradiation analysis. - Cooperation with EAC will continue. The TRANSURANUS code will be further developed to include the treatment of partially destroyed pins. The fuel pin codes developed at the Institute will undergo verification with the results of CABRI power burst experiments. Knudsen cell equipment combined with mass spectrometers will be used for extensive source term studies. Short description of evolution of work in 1992. Participation in PHEBUS PF and post-irradiation examination of BR3 will continue. Fuel samples from LAMBDA and CABRI experiments will be analysed. Further cooperation with EAC depends on the respective programme planning (Ispra).