109 research outputs found

    Infrastructure and international cooperation in research and knowledge transfer: supporting access to key infrastructures and pan-European research − lessons learned

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    Access to research infrastructures has been supported by the European Commission under different financial schemes. During the 6th EURATOM Framework Programme the instrument introduced by the European Commission were the Integrated Infrastructure Initiatives (I-3). Moreover, funding schemes to support Education and Training for students and professional developments were defined also. The main difference between these two funding schemes is that I-3 are topic-driven projects with access to infrastructure components, while the Education and Training related projects have a mobility component that is applied for the different research topics. The outcome of projects as TALISMAN (I-3), EFNUDAT/NUDAME (I-3), GENTLE (mobility), ENEN-plus (mobility), NUGENIA-plus (mobility within TA of NUGENIA) and ESNII-plus (I-3 similar) will be shortly presented as well as the future European Commission plans in the field of access to research infrastructure

    On the EU-Japan roadmap for experimental research on corium behavior

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    A joint research roadmap between Europe and Japan has been developed in severe accident field of light water reactors, focusing particularly on reactor core melt (corium) behavior. The development of this roadmap is one of the main targets of the ongoing EU project SAFEST. This paper presents information about ongoing severe accident studies in the area of corium behavior, rationales and comparison of research priorities identified in different projects and documents, expert ranking of safety issues, and finally the research areas and topics and their priorities suggested for the EU-Japan roadmap and future bilateral collaborations. These results provide useful guidelines for (i) assessment of long-term goals and proposals for experimental support needed for proper understanding, interpretation and learning lessons of the Fukushima accident; (ii) analysis of severe accident phenomena; (iii) development of accident prevention and mitigation strategies, and corresponding technical measures; (iv) study of corium samples in European and Japanese laboratories; and (v) preparation of Fukushima site decommissioning

    Melting transition measurements in uranium dioxide

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    EThOS - Electronic Theses Online ServiceGBUnited Kingdo

    High-Temperature Thermodynamics at the Institute for Transuranium Elements of Karlsruhe (Germany): Experiments and Modelling

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    This work summarizes the scenario of high temperature experimental thermodynamics, including a short review of the main experimental methods currently employed at the European Commission's Joint Research Centre – Institute for Transuranium Elements (ITU) of Karlsruhe (Germany) for the thermodynamic characterization of physico-chemical systems at high and extreme temperatures. Some modelling methods for the thermodynamic assessment of phase diagrams are also presented. Some recent results concerning material systems of interest for high-temperature applications are shown as examples.JRC.E.3-Materials researc

    Melting transition measurements in uranium dioxide

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    The broad objective of research described in this thesis was the experimental determination of the solid / liquid transition in both stoichiometric and hyperstoichiometric uranium dioxide. Experimental information in this field constitutes a necessary reference for the analysis of hypothetical nuclear reactor accidents and, in particular, for the formulation of an equation of state (EOS) for uranium dioxide. A review of previous research on the same topic revealed that only few and uncertain experimental data were available prior to this work, obtained with conventional thermal analysis techniques in which it was not possible, at temperatures close to melting, to prevent sample contamination from the containing material and non- congruent evaporation. The experimental approach in the current research consisted mainly of the development of a laser heating method that enabled fast (tens of ms) melting / freezing experiments under containerless conditions, during which the sample could be kept under a buffer gas at high pressure (tens of MPa) in order to suppress any evaporation. In this way, the main difficulties encountered by previous researchers were overcome. U02~x samples with 0 ≀ x ≀ 0.21 were prepared starting from original nuclear-grade pellets and analysed. Thermograms were recorded with fast pyrometers and interpreted with the help of a one-dimensional codesimulation of the measurements. In addition, a novel method for measurement of phase transition points was developed, based on the precise detection of surface reflectivity variations. The point of congruent melting was determined for the stoichiometric oxide in the pressure range between 0.1 and 250 MPa. Liquidus and solidus lines were established, for pressures between 50 and 250 MPa, in the hyperstoichiometric range investigated. The results obtained, which in a number of cases significantly differed from the existing data, were finally used for a better assessment of the phase diagram of the system U02~x in the vicinity of the melting transition

    Erratum for the Report “Molten uranium dioxide structure and dynamics” by L. B. Skinner, C. J. Benmore, J. K. R. Weber, M. A. Williamson, A. Tamalonis, A. Hebden, T. Wiencek, O. L. G. Alderman, M. Guthrie, L. Leibowitz, J. B. Parise

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    In the Report Molten uranium dioxide structure and dynamics, on page 987, column 1, the first two full sentences should be replaced with “In 2002, Manara et al. measured a melting slope (dTm/dP) that is a factor of 1.5 to 2 steeper than expected from the recommended volume change on melting and enthalpy of fusion values (11, 16). Later measurements, however, find a shallower melting slope and reach agreement with the Clausius-Clapeyron relation (3), suggesting congruent melting. All these measurements point toward a relatively low melting entropy less than 3 Nk, consistent with the high O disorder and rapid O exchange observed in these MD models close to the melting point.” The sentences have been corrected in the HTML and PDF versions online.JRC.E.3-Materials researc

    Thermodynamic assessment of the Th-U-Pu system

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    Thermodynamic assessments of the Th-U and Th-Pu binary systems are performed in this study according to Calphad method and together with the data on the U-Pu system, which has been already published in the literature, the Th-U-Pu ternary system is determined. All available experimental data from the literature were used for the binary system assessments and based on them the Gibbs energy properties of the unknown phases have been optimized. For the excess Gibbs energy of the liquid phase the ionic liquid model has been used, whereas for solid solutions the Redlich-Kister description was selected.JRC.E.3-Materials researc

    Advances in the Experimental Determination of the UraniumÂżOxygen Phase Diagram at High Temperature

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    Due to its complex phase diagram and the employment of UO2 as a nuclear fuel, the binary system UÂżO is of great interest both scientific and technological. Numerous experimental and theoretical studies have been carried out in the last 45 years in order to determine the properties of this system, leading to a precise definition of a considerable part of the state diagram in the region ranging from pure uranium to stoichiometric UO2, and at temperatures lower than 1500 K, up to the oxide U4O9. However, due to the poor chemical stability of OÂżU compounds with high oxygen content at high temperature (O/U>2,T >2000 K), an important part of the phase diagram still lacks experimental data. In this work measurements are presented on the melting transition of the stoichiometric and hyperstoichiometric dioxide UO2+x up to x = 0.21, and on the melting point of the higher oxide U3O8. These measurements were performed under buffer gas pressures varying between 10 and 250MPa, using a method based on subsecond laser heating developed to overcome experimental difficulties encountered by previous researchers.JRC.DG.E.3-Materials researc
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