Institute of Energy and Climate ResearchIEK-6: Nuclear Waste Management Report 2013 / 2014 Material Science for Nuclear Waste Management

摘要

This is the third bi-annual report of the Nuclear Waste Management section of theInstitute of Energy and Climate Research (IEK-6) at Forschungszentrum Jülich since2009 – almost a tradition. Our institute has seen two more years with exciting scientific work,but also major changes regarding nuclear energy in Germany and beyond. After the reactoraccident in Fukushima (Japan) in 2011, it was decided in Germany to phase out electricityproduction by nuclear energy by 2022. It seems clear, that the decommissioning of thenuclear power plants will take several decades. The German nuclear waste repositoryKonrad for radioactive waste with negligible heat generation (all low level and some of theintermediate level radioactive waste) will start operation in the next decade. The new siteselection act from 2013 re-defines the selection procedure for the German high level nuclearwaste repository. Independently of the decision to stop electricity production by nuclearenergy, Germany has to manage and ultimately dispose of its nuclear waste in a safe way.Our basic and applied research for the safe management of nuclear waste is focused onradiochemistry and materials chemistry aspects – it is focused on the behaviour ofradionuclides and radioactive waste materials within the back-end of the nuclear fuel cycle. Itis organized in four areas: (1) research supporting the scientific basis of the safety case of adeep geological repository for high level nuclear waste, (2) fundamental structure research ofradionuclide containing (waste) materials (3) R & D for waste management concepts forspecial nuclear wastes and (4) international safeguards.A number of excellent scientific results have been published in more than 80 papers ininternational peer-reviewed scientific journals in 2013 - 2014. Here, I would like to mentionfour selected scientific highlights – more can be found in this report:(1) The retention of radionuclides within a nuclear waste repository system by secondaryphases for the long-term safety assessment is one of the major research topics in theinstitute. The fundamental understanding of a long-standing open issue regarding thethermodynamics of radium-barium-sulfate solid solutions and its applicability in long-termsafety assessments for nuclear waste disposal could be resolved. This was achieved by anovel approach combining atomistic simulations, radiochemical batch-type laboratoryexperiments and modern analytical techniques supported by thermodynamic modellingallowing a reliable description of Ra solubility control by a (Ba,Ra)SO4 solid solution. Thisresearch is supported by the Swedish waste management agency SKB.(2) A major step forward was achieved regarding the prediction of actinide- and lanthanidebearingmaterials properties by atomistic simulations. Performance tests of the DFT+Umethod for calculations of f-element-bearing systems (the Hubbard U parameter derivedfrom first principle methods) showed that this method, in contrast to standard DFT, results inexceptionally good predictions of the formation and reaction enthalpies as well as thestructures of lanthanide- and actinide-bearing materials.(3) The actinide solid state chemistry group has been very active in recent years tounravel the crystal structure of actinide containing oxo-salts. From the 1101 new crystalstructure entries in the ICSD crystal structure database between 2005 and 2012, Prof.Evgeny Alekseev has contributed to 98 entries (almost 10%).