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- Rodriguez-Fernandez, A., et al.
(författare)
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X-ray forward diffraction wave-front propagation in Si and C single crystals : Simulations and experiments
- 2020
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Ingår i: Advances in Computational Methods for X-Ray Optics V. - : SPIE. - 1996-756X .- 0277-786X. - 9781510637924 ; 11493
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Konferensbidrag (refereegranskat)abstract
- The emergence of new high brilliance and high coherence facilities such as X-ray Free Electron Lasers (XFELs) and 4th generation synchrotrons open a new era in X-ray optics. Dynamical diffraction effects before disregarded are starting to play a role in the beam control of large scale facilities. In the case of XFEL facilities the temporal characteristics of the dynamical diffraction by thin perfect crystals can be used as a tool to generate femtosecond monochromatic pulses, in the case of self-seeding in the hard X-ray regime, but could even be used as method to characterize materials in this temporal range. In this contribution we present the first steps in the understanding of the spatial-displacement dependence of forward beams diffracted by thin crystals. The data collected by this technique is compared with crystal models based in dynamical diffraction theory. This type of study could open a new field to understand low strain materials in the femtosecond regime.
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| 2. |
- Altmaier, M., et al.
(författare)
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TALISMAN - A European Commission FP7 project promoting transnational access to large infrastructures for a safe management of actinides
- 2014
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Ingår i: Plutonium Futures: The Science 2014; Las Vegas; United States; 7 September 2014 through 12 September 2014. - 9781510808089 ; , s. 165-166
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Konferensbidrag (refereegranskat)abstract
- TALISMAN is a large international project funded within the European Commission FP7 EURATOM framework. The aim of TALISMAN is to offer transnational access to large infrastructures for a safe management of actinides. Although clearly focusing on R&D activities from European Union member states, TALISMAN is also open to participation from non-EU countries. TALISMAN is coordinated by CEA (contact by stephane.bourg@cea.fr), supported by a Governing Board and the ExCom. Dedicated studies on Pu containing materials are integral part of TALISMAN. Safety issues are of fundamental importance for the acceptance and sustainable application of nuclear energy. Actinides play a central role in the nuclear fuel cycle from mining, fuel fabrication, energy production, up to reprocessing, partitioning and transmutation treatment of used fuel, and finally the management and disposal of radioactive waste. Fundamental understanding of actinide properties and behavior in fuel materials during the separation processes and in geological repositories is an imperative prerequisite to tackle the related safety issues. Unravelling the complexity of the actinide components of used nuclear fuel certainly represents one of the great challenges in nuclear science. To meet the needs of safe and sustainable management of nuclear energy it is essential to maintain a high level of expertise in actinide sciences both on a European and international level. Educating and training the next generation of scientists and engineers who will contribute to developing safe actinide management strategies is a key mission. Because actinides are radioactive elements and handling requires specific safety measures, their study requires advanced tools and facilities that are only available to a limited extent. Only a few academic and research organisations have the capabilities and licenses to work on actinide elements. From a European perspective it is therefore strategic to coordinate the existing actinide infrastructures in Europe and strengthen the community of scientists working on actinides. Within TALISMAN we offer (for positively evaluated scientific research proposals submitted in reply to a specific TALISMAN call) access to the previous ACTINET Pooled Facilities (CEA Atalante and CEA DPC, France; ITU Laboratories & hot-cells, European Commission; KIT-INE laboratories and KIT-INE beamline, Germany; HZDR-IRE & ROBL, Germany; PSI microXAS Beamline, Switzerland) to which two new facilities have been added: NNL Central Lab in the UK and CHALMERS in Sweden. TALISMAN is also open to scientists and research organizations from outside the European Union. TALISMAN leads and coordinates a network of actinide facilities across Europe, but also manages a network between facilities and users to increase the knowledge for a safer management of actinides. TALISMAN also enhances the efforts made to support education and training issues by continuing the former ACTINET Summer School series and travel grant attributions for attending international conferences like the Plutonium Futures series. The TALISMAN project website is regularly updated and offers detailed information on all TALISMAN activities at http://www.talisman-project.eu. This is including contact addresses, TALISMAN newsletters, announcements and description of open and forthcoming calls for transnational user access and indicates several other options to perform actinide research within the TALISMAN context.
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| 5. |
- Yang, H., et al.
(författare)
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Reductive precipitation of neptunium on iron surfaces under anaerobic conditions
- 2017
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 496, s. 109-116
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Tidskriftsartikel (refereegranskat)abstract
- Reductive precipitation of the radiotoxic nuclide Np-237 from nuclear waste on the surface of iron canister material at simulated deep repository conditions was investigated. Pristine polished as well as pre corroded iron specimens were interacted in a deoxygenated solution containing 10-100 mu M Np(V), with 10 mM NaCl and 2 mM NaHCO3 as background electrolytes. The reactivity of each of the two different systems was investigated by analyzing the temporal evolution of the Np concentration in the reservoir. It was observed that pre-oxidized iron specimen with a 40 tm Fe3O4 corrosion layer are considerably more reactive regarding the reduction and immobilization of aqueous Np(V) as compared to pristine polished FeM surfaces. Np-237 immobilized by the reactive iron surfaces was characterized by scanning electron microscopy as well as synchrotron-based micro-X-ray fluorescence and X-ray absorption spectroscopy. At the end of experiments, a 5-8 tm thick Np-rich layer was observed to be formed ontop of the Fe3O4 corrosion layer on the iron specimen. The findings from this work are significant in the context of performance assessments of deep geologic repositories using iron as high level radioactive waste (HLW) canister material and are of relevance regarding removing pollutants from contaminated soil or groundwater aquifer systems.
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