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 "Vorkommen und Ausbreitung der Transurane im Meer" wird vom Umweltbundesamt gefördert und von Deutsches Hydrographisches Institut durchgeführt. Untersuchungen zum Vorkommen und Verhalten kritischer Transurane (v.a. Plutonium).
Das Projekt "Sicherheit des Kernbrennstoffzyklus und ihre Auswirkungen auf die Umwelt, 1988-1991" wird vom Umweltbundesamt gefördert und von European Commission, Joint Research Centre (JRC). Institute for Transuranium Elements (ITU) durchgeführt. To evaluate and, if possible, further reduce the risk associated with the preparation, processing and temporary storage of nuclear fuels by studying actinide formation and recycling, generation and dispersion of nuclear aerosols and selected topics related to the reprocessing of nuclear fuels. General Information: Progress to end 1990. The results of a KNK II irradiation experiment with minor actinides has been compared to theoretical calculations in cooperation with CRIEPI, and general agreement was found. The post-irradiation examination of the SUPERFACT experiment in Phenix has begun. As a follow up of the workshop on Transmutation and Partitioning working groups have formed to define future research needs. A new separation scheme for minor actinides has been set up. - The size distribution of resuspended oxide fuel particles from burning substrates (latex, aluminium) was measured. A facility was conceived and designed to study the behaviour of nuclear aerosols in long ducts. Results of project work have been presented at 5 international conferences. One article appeared in Radiochimica Acta. Detailed description of work foreseen in 1991 (expected results). Destructive post-irradiation examination of SUPERFACT will start. The analyses of the second irradiation experiment in KNK II will begin. The knowledge base to compare proposed transmutation strategies will be tested. Basic studies will include work on phase diagrams, thermal conductivity and dissolution on different fuels. Minor actinides will be recovered from scrap. Studies to improve the separation of minor actinides from high level waste begin. - A facility will be commissioned and experiments started to investigate aerosol behaviour in long ducts. - FIRE-experiments will be performed upon request. Short description of evolution of work in 1992. The recovery of minor actinides from specially prepared irradiated fuel will start. Cross sections for minor actinide transmutation will be deduced from the irradiation experiments. Key experimental studies to test other transmutation schemes will begin. Basic data for different minor actinide containing fuels will be measured. - Duct-experiments will continue in an effort to characterize nuclear aerosols in various accident scenarios.
Das Projekt "Saferty of actinides in the nuclear fuel cycle, 1992-1994" wird vom Umweltbundesamt gefördert und von European Commission, Joint Research Centre (JRC). Institute for Transuranium Elements (ITU) durchgeführt. Objective: To carry out safety studies with nuclear fuels under long-term and off-normal conditions, to evaluate and reduce risks associated with storing and handling actinides, to carry out basic solid state studies on actinides and collect data and bibliographic references on properties and applications of transuranium elements. General Information: Progress to end 1991. The Institute continued efforts to contribute to the safety of nuclear fission by concentrating its research activities on investigations of the behaviour of nuclear fuel after prolonged irradiation and under variable reactor operating conditions. Mechanism for the release of fission products from irradiated fuel were further elucidated, and the formation of particular structural features which may limit the fuel lifetime were better understood. First results of the post-irradiation examination of nitride fuels irradiated in the Fench PHENIX reactor were obtained, demonstrating the technological potential and the limitations of this fuel type. The measurement of the physical fuel properties of nuclear fuels at extremely high temperatures was continued, and first results of the thermal expansion of uranium dioxide for above its melting temperature were obtained. A facility was installed in order to study possibilities of (nuclear) aerosol agglomeration under dynamic conditions in a high-power acoustic field at ultrasonic and audible frequencies. Mixed oxide fuel rods containing minor actinides (MA), which had been irradiated in a fast reactor (PHENIX) in order to study possibilities of MA transmutation, were analysed. Np-based specimens, mostly in the form of single crystals, were prepared for basic experimental solid state physics studies at the Institute and in various overseas and European laboratories. Progress was made in understanding the electronic structure of transuranium elements and their compounds by further development of theories and experimental efforts in high-pressure research and photoelectron spectroscopy. Equipment for Moessbauer spectroscopy and for other physical property measurements at cryogenic temperatures was installed in the new transuranium research user facility. Work to adapt instruments and methods developed at the Institute in the frame of the above programme (fast multi-colour pyrometry and enhancement of industrial filter efficiency) to industrial application was continued, together with partners from industry. Four patent proposals (on acoustically enhanced off-gas scrubbing, on laser-enhanced extraction, on production methods for Ac-225 and Bi-213, and on the preparation of amorphous substances) were filed in 1991. 42 articles in scientific-technical journals were published (or submitted for publication) and 82 lectures were given in conferences on various subjects dealing with the safety of actinides in the nuclear fuel cycle in 1991. Detailed description of work foreseen in 1992 (expected results). Studies of fission product migration ...
Das Projekt "Characterisation of nuclear waste forms, 1992-1994" wird vom Umweltbundesamt gefördert und von European Commission, Joint Research Centre (JRC). Institute for Transuranium Elements (ITU) durchgeführt. Objective: To characterize vitrified high-level waste forms and unprocessed spent fuel with respect to properties relevant to their behaviour under conditions of long-term storage, i.e. radioactive nuclide inventory, thermal conductivity, thermal and mechanical stability, redistribution of actinides and fission products within waste materials, radiation damage, resistance to corrosive agents, and to investigate leaching of waste forms with various leachant compositions. General Information: Progress to end 1991. A major effort was made to extend studies on the characterisation of nuclear waste to unprocessed nuclear fuel in view of its behaviour under temporary and final storage conditions. These investigations comprised the interaction of irradiated UO2 with water and the development and testing of equipment for the non- destructive analysis of irradiated fuel rods by passive neutron interrogation. The development of a code (COCAINE) to model the consequences of ground water intrusion in a spent fuel storage facility got under way. Leach tests were carried out with active waste glass samples (type R7T7), and the same material was subject to micro structural analysis. Instruments to measure the mechanical properties of waste glasses were tested with inactive glasses. The results of this work were described in 4 publications. Detailed description of work foreseen in 1992 (expected results). Leaching experiments with UO2 and MOX fuels will be performed in order to study the effect on the leach rate of oxidising agents in a liquid and/or gaseous environment. The oxidation of UO2 fuel in air/water, N2/water and in air at temperatures deeper than 500 degrees celsius will be studied by thermogravimetry. The newly developed neutron interrogation equipment will be applied in order to determine actinide concentrations in various types of fuel rods. Equipment for the speciation of leachats will be developed and tested. The COCAIN code which models the consequences of ground water intrusion in a spent fuel storage facility will be further developed. Short description of evolution of work in 1993. Future studies on waste characterisation will concentrate more or lesson spent fuel behaviour under temporary and final storage conditions. They will be pursued in an interplay between experiments and modelling activities. Achievements: A major effort was made to extend studies on the characterization of nuclear waste to unprocessed nuclear fuel in view of its behaviour under temporary and final storage conditions. These investigations comprised the interaction of irradiated uranium oxide with water and the development and testing of equipment for the non-destructive analysis of irradiated fuel rods by passive neutron interrogation. The development of a code (COCAINE) to model the consequences of ground water intrusion in a spent fuel storage facility got under way. Leach tests were carried out with active waste glass samples (type R7T7), and the same ...
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).
Das Projekt "Nuclear waste forms characterisation, 1988-1991" wird vom Umweltbundesamt gefördert und von European Commission, Joint Research Centre (JRC). Institute for Transuranium Elements (ITU) durchgeführt. Objective: To characterize vitrified high-level waste forms and unprocessed spent fuel with respect to properties relevant to their behaviour under conditions of long-term storage, i.e. radioactive nuclide inventory, thermal conductivity, thermal and mechanical stability, redistribution of actinides and fission products within waste materials, radiation damage, resistance to corrosive agents, and to investigate leaching of waste forms with various leachant compositions. General Information: Progress to end 1990. Leach tests on active glasses showed no noticeable differences in comparison with non-active specimens subject to the same treatment except for the behaviour of the actinides which needs further study. Leaching tests on high burn-up spent fuel samples were initiated. Tests on the characterization of cement matrix for solidification of ILLW were concluded, and new analytical methods were applied (Inductively coupled plasma mass spectrometry). A prototype of an autoclave for the leaching under realistic resitory conditions was developed. A parametric study ( determination of Eh, pH, T, (O2), (CO3)), of UO2 oxidation by leaching was initiated. Scouting experiments with irradiated UO2 were carried out. A neutron counting system is being developed for passive neutron interrogation of individual fuel rods. Gamma-spectroscopy is performed using an existing facility. Interpretation of the measured signatures is achieved through isotopic correlations. A micro-gamma scanning device to measure the distribution ofamma emitters in waste forms went into operation. A study of the mechanical state and of radiation damage on matrix dissolution was launched. Results obtained in this context were published in a EUR report and presented at 4 occasions at international conferences. Detailed description of work foreseen in 1991 (expected results). New autoclaves for spent fuel and glass leaching experiments will be tested and used. Leach tests on selected active samples with fully characterized structures will continue, as well as tests with SIM fuel and, to a limited extent, ceramic waste forms. A laser cutting device for the machining of controlled flaws in fuel pins will be installed. R7T7-glasses and spent fuels will be characterized in a cooperation with CEA-Marcoule and KfK-INE Karlsruhe. High burn-up pins from BR-3 will be leached at pre-termined oxygen potentials A Community exercise for the selection and standardization of waste characterization procedures will be launched. New analytical methods will be applied to Np speciation. NDA will be applied to pins of spent fuel. Neutron counting equipment will be calibrated using a Cf-252 source. Gamma/neutron emission tomography will be installed for the characterisation of spent fuel cross sections. Radiation damage studies will continue. Short description of evolution of work in 1992 Leach testing of glasses and spent fuel samples will continue. Characterization techniques will be refined. ...
Das Projekt "Fuel behaviour under accident contitions, 1992-1994" 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 reactor accident mechanism by providing support to code development and application, by specifying and characterising fission products to be released from fuel in a particular accident scheme and by developing and applying specialised instrumentation for in-pile tests. General Information: Progress to end 1991. In-pile equipment for safety studies with nuclear fuels has been developed and tested (ultrasonic thermometers). An analytical solution for the transport of gaseous species in nuclear fuel pore channels under transient conditions has been proposed. A new version of the MITRA code has been applied to study transport and release of radioactive fission products from irradiated fuel. The release of volatile fission products from ThO2 with a simulated burn-up of 4 per cent has been studied. Code development work as a contribution to the establishment of a European Accident Code (in collaboration with Ispra) continued. Three articles on modelling work related to problems of reactor safety were published in 1991. Detailed description of work foreseen in 1992 (expected results). Characterisation of irridiated fuel to be subjected to in-pile fission products release tests. Application and extension of existing mathematical models to studies of fission product migration observed in transient tested UO2 under the electron microscope. Short description of evolution of work in 1993. Continuation of experimental and theoretical studies of fission product migration and release. Achievements: In pile equipment for safety studies with nuclear fuels has been developed and tested (ultrasonic thermometers). An analytical solution for the transport of gaseous species in nuclear fuel pore channels under transient conditions has been proposed. A new version of the MITRA code has been applied to study transport and release of radioactive fission products from irradiated fuel. The release of volatile fission products from thorium oxide (THO2) with a simulated burn up of 4 per cent has been studied. Code development work as a contribution to the establishment of a European accident code continued.
Das Projekt "Infrasound scavenging of aerosols" wird vom Umweltbundesamt gefördert und von European Commission, Joint Research Centre (JRC). Institute for Transuranium Elements (ITU) durchgeführt. Objective: Objective of the work is: To test the feasibility of sonic agglomeration of aerosol particles with low frequency sound. At a frequency of 20 kHz, the attenuation of sound waves in air is about 103 times lower than with 20 kHz, which would open up the possibility of sonic aerosol precipitation over a range of hundreds to thousands of meters. General Information: It is intended to: set up an infrasound source operating at 20 Hz with a power rating of 1 kW in a 170 m3 test chamber. The sound source will be supplied on loan from the company INFRASONIC in Sweden; to measure with this device in operation agglomeration rates of a chemical fog aerosol up to particle concentrations of 106 cm-3 and mass loadings of 1 g m-3; to repeat the above experiments with aerosol created from 5 kg of burning rubber; to inject seed aerosols into the original aerosol (chemical fog and soot) and measure possible enhancements in scavenging. Achievements: The feasibility of sonic agglomeration of aerosol particles with low frequency sound was tested. At a frequency of 20 Hz, the attenuation of sound waves in air is about 103 times lower than with 20 kHz, which would open up the possibility of sonic aerosol precipitation over a range of hundreds to thousands of meters. Preliminary test with a chemical combustion engine (pulse jet) running at a fundamental frequency of 200 Hz were disturbed by secondary effects due to turbulent hot exhaust gases. Nevertheless, measurable agglomeration took place.
Das Projekt "Radionuklidsorption (U, Pu, Am, Cm) an Sedimenten aus Gorleben" wird vom Umweltbundesamt gefördert und von Bundesanstalt für Materialprüfung, Abteilung 6, Stoffartunabhängige Verfahren durchgeführt. Bestimmumg von Sorptions- und Desorptionskoeffizienten des U, Pu, und Cm fuer Lockergesteine und bindige Proben aus dem Raum Gorleben unter Verwendung der zugehoerigen Grundwaesser. Schuettel- und Saeulenversuche.
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