Das Projekt "Safety studies with nuclear fuels, 1988-1991" wird vom Umweltbundesamt gefördert und von European Commission, Joint Research Centre (JRC). Institute for Transuranium Elements (ITU) durchgeführt. Objective: To study mechanisms and properties determining fuel and fission product behaviour during both, base and off-normal conditions. This activity involves unirradiated and irradiated 'classical' and 'improved' fuel samples of various composition and over a wide range of temperatures, up to very high burn-up, and makes use of appropriate computer models. The final aim of the activity is the improvement of the safety of fuel operation in a reactor. General Information: Progress to end 1990. The Laboratory continued its cooperation with the International Fission Gas Release Project Riso III (Dk) by incorporating the extensive experimental data resulting from the programme into the OFT data bank and evaluating them with existing TU fuel performance codes. - The OECD-coordinated activity for analysing fuel and fuel debris of the Three Mile Island (TMI) damaged reactor has been concluded. An apparatus for thermal diffusivity measurements on active specimens with the laser flash technique has been constructed. - Nitride fuels with a 'tailored' structure and heterogeneous fuels (U, Pu)O2 and UN) were fabricated for short-term irradiations in the HFR-reactor. Irradiations of fuels for future reactors to test their behaviour at the beginning of life (BOL) and at the end of life (EOL), NILOC (HFR) and NIMPHE (PHENIX), respectively, have been continued. Out-of-pile tests were performed to study changes in structure and composition of mixed nitride fuel pins in an axial temperature gradient. - Measurements of the heat capacity of UO2 up to 8000K were concluded and the results are being analysed. Radiative properties of oxides (thoria, urania, zirconia) were measured in the solid and the liquid range. A model for the total emissivity of urania was developed. - The code MITRA has been adapted to perform source term calculations. A computer code for the calculation of the thermo chemical equilibrium of fission products was written and a database for fission product compounds has been implemented with interface to the SOLGASMIX/MITRA codes. A shielded Knudsen cell for irradiated UO2 fuel has been assembled. - Work in 1990 on the safety of nuclear fuels has resulted in 33 (status September '90) contributions to conferences, articles in scientific journals, reports and chapters in books; two patents were granted. Detailed description of work foreseen in 1991 (expected results). Riso III results will undergo final evaluation and fuel work will concentrate on MOX fuel and on the structural and chemical changes at local burn-ups of up to 15 per cent . Laboratory work will principally deal with SIMFUEL with 6 and 8 per cent burn-up. Modelling work will continue. Annealing tests will be performed under oxidizing and reducing atmosphere on U02 samples irradiated up to 55 GWd/t, in order to determine fission gas release as a function of O/M . A remotely controlled thermal diffusivity apparatus will be mounted in a hot cell. BOL and EOL irradiations NILOC and ...
Das Projekt "Optimierung der Abwasserreinigungssysteme der Firma Otto Oeko-Tech bei der kommunalen Abwasserreinigung" wird vom Umweltbundesamt gefördert und von Technische Universität Darmstadt, Institut für Wasserversorgung und Grundwasserschutz, Abwassertechnik, Abfalltechnik, Fachgebiet Industrielle Stoffkreisläufe, Umwelt- und Raumplanung durchgeführt. Die Firma Otto Oeko-Tech (Koeln) hat den in ihrem Hause fortentwickelten HCR-Reaktor (Hochleistungs-Compact-Reaktor) zur Reinigung hochbelasteter Abwaesser aus der Papier- und Nahrungsmittelindustrie sowie bei der Faekalschlammbehandlung mit sehr gutem Erfolg eingesetzt. Neben einer Reduzierung der organischen Schmutzparameter BSB5 und CSB wurde in Untersuchungen festgestellt, dass die Reinigung der Abwaesser mit geringen Kosten erreicht wurde. Der HCR-Reaktor soll nun vor diesem Hintergrund in eine Verfahrenskette zur Reinigung kommunaler Abwaesser insbesondere zur Stickstoffelimination integriert werden. An einer von der Firma Otto Oeko-Tech zur Verfuegung gestellten Versuchsanlage im technischen Massstab sollen Versuche mit dem Ziel der Reduzierung der Investitions- und Betriebskosten bei gleichzeitig guten Reinigungsleistungen mit hoher Prozessstabilitaet durchgefuehrt werden.