Radioactive waste has been accumulated at CERN as unavoidable consequence of the use of particle accelerators. The elimination of this waste towards the final repositories in France and Switzerland requires the determination of the radionuclide inventory. In order to calculate the residual induced radioactivity in the waste, it is necessary to determine the spectra of secondary particles which are responsible for the material activation. In complex irradiation environments like in an accelerator tunnel it is expected that the secondary particle spectra vary with the characteristics of the machine components in a given section of tunnel. In order to obtain the production rates of the radionuclides of interest the spectra of secondary particles are to be folded with the appropriate cross sections. Though technically feasible, it would be impractical to calculate the particle spectra in every area of any machine and for all possible beam loss mechanisms. Moreover, a fraction of the waste has unknown radiological history, which makes it impossible to associate an item of waste to a precise area of the machine. Therefore it is useful to try to calculate “representative spectra”, which shall apply to a relatively large part of the accelerator complex at CERN. This thesis is dedicated to the calculation of representative spectra in the arcs of the 450 GeV proton synchrotron, SPS, at CERN. The calculations have been performed using the Monte Carlo code FLUKA. Extensive simulations have been done to assess the dependence of proton, neutron and pion spectra on beam energy, size of the nearby machine component and position with respect to the beam-loss point. The results obtained suggest that it is possible to define one single set of representative spectra for all the arcs of the SPS accelerator, with a minor error associated with the use of these.

In this study, degradation of ethylene propylene diene terpolymer (EPDM) via gamma radiation and possible use of EPDM in radioactive waste management were investigated. In estimation of radiation stability and possible use of EPDM in radioactive waste management, dose rate (both high and low), irradiation environment (in water and in air), additives (carbon black, zinc oxide, plasticizer) used in formulation, peroxide type (either aliphatic or aromatic) and content were parameters which were analyzed. Three EPDM samples having different peroxides were irradiated in water and in air with two different dose rates (993 Gy/h, 54 Gy/h) to 2163 kGy (for high dose rate) and 1178 kGy (for low dose rate). Irradiation periods for low dose rate were 2.5 years (last sample) which have not been observed in literature. Characterization of irradiated EPDM samples were done by mechanical (tensile, hardness, compression), dynamic mechanical (DMA), thermal (TGA-FTIR) and morphological (ATR-FTIR, XRD, SEM) tests. High dose rate irradiations were done in predicting how far EPDM resist to radiation and which dose rate emitted waste can be immobilized and stored in EPDM for 300 years. Low dose rate irradiations were carried out in determining morphological changes in structure, thermal stability, oxygen effect and types of reactions (crosslinking, chain scisson) which were dominant in irradiated samples. According to the test results, improvement in thermal properties and decrease in elasticity on EPDM via radiation were recorded from thermal and mechanical tests respectively. Moreover, structural changes were monitored from ATR-FTIR, SEM and XRD analysis. Mechanical tests showed that irradiated EPDM samples, which were differentiated with respect to peroxide type (aliphatic, aromatic), could resist up to total absorbed doses of 3750 kGy and 3955 kGy respectively. Up to 1178 kGy in low dose irradiation, there were not much structural changes, which were observed in ATR-FTIR analysis, in EPDM chain. It was concluded that EPDM rubber used in this study were radiation stable polymer so that they could possibly be used in conditioning of radioactive waste.

There are large amount of cellulose accumulated in radioactive waste and radioactive pollution sites. It is difficult to clean up these cellulose. In general, waste treatment process can only proceed until the radiation decay to a safty level. Since most cellulolytic microorganisms could not survive in radioactive waste, the accumulation of cellulose in radioactive waste become a serious problem. Deinococcus radiodurans is highly resistant to radiation, UV light, and dryness. It is possible to use this bacterial strain in the bioremediation of radioactive waste. In this study, we found out that there was not much difference on the growth of this organism under radiation and UV light. Cellulose enzyme activity was inhibited by UV irradiation, but not by 32P radiation. The addition of D. radiodurans whole cells or its cell crude extracts could protect the cellulase from UV damage. We also successfully constructed two plasmids, that contained a cel A gene isolated from Thermotoga maritima. These two plasmids had been used to transform Escherichia coli BL21 and D. radiodurans. All transformed bacterial strains could express celA activity. The celA activities in these transformed D. radiodurans strains were not affect by UV irradiation. However, celA enzyme activity in the transformed E. coli was greatly inhibited by UV irradiation up to 78%. Hopefully these two transformed D. radiodurans bacterial strains can be applied to the bioremediation of radioactive waste.

The Institute of Safety Research (ISR) is one of the six Research Institutes of Forschungszentrum Dresden-Rossendorf e.V. (FZD), which is a member institution of the Wissenschaftsgemeinschaft Gottfried Wilhelm Leibniz (Leibnizgemeinschaft). Together with the Institutes of Radiochemistry and Radiation Physics, ISR implements the research programme „Nuclear Safety Research“, which is one of the three scientific programmes of FZD. The programme includes two main topics, i. e. “Safety Research for Radioactive Waste Disposal” and “Safety Research for Nuclear Reactors”.

Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

The Greater than Class C (GTCC) Environmental Impact Statement (EIS) evaluated the potential impacts from the construction and operation of a new facility or facilities, or use of an existing facility, employing various disposal methods (geologic repository, intermediate depth borehole, enhanced near surface trench, and above grade vault) at six federal sites and generic commercial locations. For three of the locations being considered as possible locations, consulting tribes were brought in to comment on their perceptions on how GTCC low level radioactive waste would affect Native American resources (land, water, air, plants, animals, archaeology, etc.) short and long term. The consulting tribes produced essays that were incorporated into the EIS and these essays are in turn included in this collection. This essay was produced by the Confederated Tribes of the Umatilla Indian Reservation.

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Modern Societies have to consider diverse tasks strongly related to geochemistry sciences. Examples intensively discussed in the public are restoration measures for contaminated industrial fallow grounds, the safe storage of chemical-toxic and radioactive waste, carbon dioxide sequestration to reduce green-house gas emissions, the construction and operation of deep geothermal power plants, the geochemical exploration of natural resources or water and waste water treatments, including desalination efforts. Direct and urgent aspects to be dealt with are analytical and geochemical consequences of the Fukushima Daiichi nuclear disaster. All these cases have one in common – they require reliable thermodynamic data in order to forecast the fate of chemicals in the respective environment. Whereas a variety of standard methods, such as potentiometry, solubility studies, liquid-liquid extraction or electrochemical titrations, are in widespread use to generate thermodynamic data, it is far less straightforward to assign correct reaction pathways and structural patterns to the underlying chemical transformations. This especially holds for systems with strong tendencies to complexation and oligomerization. Here, it is essential to have proof of evidence for all involved species, which cannot be provided by the aforementioned methods, and is still lacking for various metal-containing systems. Spectroscopic techniques in combination with approaches from quantum chemistry can be of great benefit for such tasks. However, their application ranges are often restricted with respect to the type of element (and redox state) that can be probed. Further handicaps are imposed by detection limits or other parameters such as pH or salinity. Moreover, the spectroscopic results are often difficult to interpret in an unambiguous way. To overcome these complications at least partially, this workshop has been initiated. It shall significantly extend the application areas of spectroscopic tools important for lanthanide and actinide chemistry. Emphasis shall be placed on the development of spectroscopic methods towards more challenging environmental conditions – such as very basic pH values, elevated temperatures, pressures, or salinities – extending the range of covered elements and redox states. Furthermore, the exploration of options for lowering detection limits and increasing spatial resolution at sufficiently high signal-to-noise ratios will support future investigations on more complex systems. An approach combining the extension of spectroscopic tools with respect to elements and parameters, improvements of experimental setups, and applications of quantum chemical methods in predictive as well as interpretative ways certainly can be very beneficial. The workshop hopefully will bundle and strengthen respective research activities and ideally act as a nucleus for an international network, closely collaborating with international partners. I am confident that the workshop will deliver many exciting ideas, promote scientific discussions, stimulate new developments and in such a way be successful.

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