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Long-living high-level radioactive waste from existing nuclear power reactors should be transmuted in short-living radio nuclides using fast neutrons provided by a spallation target in an accelerator driven subcritical system or by a fast nuclear reactor. The objective is to reduce the final disposal time of highlevel radioactive waste (plutonium, minor actinides) from some 106 years down to about 1000 years. Lead (Pb) and lead-bismuth (PbBi) are foreseen as spallation-target and coolant of such devices. The aim of the institute’s contribution is the development of advanced corrosion mitigation processes especially for parts under high loads like fuel claddings or pump materials in contact with liquid Pb or PbBi. Pulsed large area electron beams (GESA) are used to modify the surface of steels such that they fulfill the requirements of their surrounding environment. Corrosion test stands for exposure of specimens under relevant conditions are developed and operated. Conditioning the Pb-alloy with regard to its oxygen concentration and the transport of oxygen in PbBi are additional aspects of the work. All tasks are embedded in European and international projects and cooperations like e.g., MaTISSE, MYRTE and GEMMA.

The Department for Pulsed Power Technology is focusing on research and development of pulsed power technologies and related applications. The applications involves the electroporation of biological cells for extraction of cell contents (PEF- process), dewatering and drying of green biomass, pre-treatment of micro algae for energetic use and sustainable reduction of bacteria in contaminated effluents. Another key research topic is devoted to the development of corrosion barriers and materials for improved compatibility of structural materials in contact with liquid metal coolants. This year's report focuses primarily on the activities and results of ongoing third-party funded projects of the department.

© 2017 Elsevier Ltd X-ray absorption spectroscopy was carried out to investigate local structural changes around Fe and Zn atoms of the nano-crystalline spinel ferrite ZnFe2O4 anode material at various states-of-charge during the 1st and 2nd lithiation/de-lithiation. From the X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), we propose a possible structure evolution process of the ZnFe2O4 electrode during the 1st discharge and charge cycle. A mixture of metallic iron, ZnO, metallic zinc, LiZn and Li2O phases seem to be formed as the cell is firstly discharged to 0.02 V. Instead of the original ZnFe2O4 spinel phase, the metallic iron and zinc particles are re-oxidized to Fe2O3 and ZnO phases during the subsequent de-lithiation. A reversible redox reaction between Fe2O3, ZnO and lithium ions is found in the 2nd cycle. The formation of SEI layer in the initial cycles plays a major role in the irreversible capacity of the electrode. The inactive disordered ZnO formed due to the conversion reaction of ZnFe2O4 during the 1st lithiation is probably the main reason for the poor electrochemical behavior of the nano-crystalline ZnFe2O4 electrode.

© 2016 Elsevier B.V. Nano-crystalline NiFe2O4 particles were synthesized and used as active electrode material for a lithium ion battery that showed a high discharge capacity of 1534 mAh g−1 and charge capacity of 1170 mAh g−1 during the 1st cycle. X-ray absorption spectroscopy including XANES and EXAFS were used to investigate electronic and local structural changes of NiFe2O4 during the 1st lithiation and de-lithiation process. As lithium is inserted into the structure, tetrahedral site Fe3+ ions are reduced to Fe2+ and moved from tetrahedral sites to empty octahedral sites, while Ni2+ ions are unaffected. As a consequence, the matrix spinel structure collapses and transforms to an intermediate rock-salt monoxide phase. Meanwhile, the inserted Li is partially consumed by the formation of SEI and other side reactions during the conversion reaction. With further lithiation, the monoxide phase is reduced to highly disordered metallic Fe/Ni nanoparticles with a number of nearest neighbors of 6.0(8) and 8.1(4) for Fe and Ni, respectively. During subsequent de-lithiation, the metal particles are individually re-oxidized to Fe2O3 and NiO phases instead to the original NiFe2O4 spinel phase.

A detailed analysis of specimen composition, water uptake and their interrelationship in the systems La6 xWO12 amp; 948; 0.4 amp; 8804; x amp; 8804;0.8 and La6 xW1 yMyO12 amp; 948; 0 amp; 8804;y amp; 8804;0.2; M Mo, Re is presented. The three specimen series were investigated in dry and wet D2O conditions. A systematic trend in mass loss and onset temperature variation was observed in La6 xWO12 amp; 948; 0.4 amp; 8804;x amp; 8804;0.8 . Even very small amounts lt; 1 wt of secondary phases were found to notably modify the specimen s water uptake and onset temperature of mass loss. The theoretical model for vacancy concentration available was used to calculate the vacant oxygen sites starting from mass loss values determined by thermogravimetry. A discrepancy between the calculated and observed concentration of vacant oxygen sites is observed for all three systems. The effect of substitution of W by Re or Mo on the vacancy amount is explained taking into account diffraction measurements and information on the oxidation state of the substituting elements Mo and Re

© The Royal Society of Chemistry. In this study, self-prepared nanostructured CuO electrodes show no capacity decay for 40 cycles at 0.1C in Li metal cells. The reaction mechanisms of the CuO electrodes are investigated. With the help of in situ EIS, in situ XRD, TEM, XAS, SQUID, IC and GC-MS, it is found that the as-prepared CuO electrode undergoes significant phase and composition changes during the initial lithiation, with the transformation of CuO to nano-crystalline Cu. During the 1st delithiation, Cu is inhomogeneously oxidized, which yields a mixture of Cu2O, Cu2−xO and Cu. The incomplete conversion reaction during the 1st cycle is accompanied by the formation and partial decomposition of the solid electrolyte interphase (SEI) as the side reactions. Nevertheless, from the 1st to the 5th delithiation, the oxidation state of Cu approaches +2. After an additional formation step, the transformation to Cu and back to Cu2−xO remains stable during the subsequent long-term cycling with no electrolyte decomposition products detected. The LiNi1/3Mn1/3Co1/3O2 (NMC-111)/CuO full cells show high capacities (655.8 ± 0.6, 618.6 ± 0.9 and 290 ± 2 mA h g−1 at 0.1, 1 and 10C, respectively), within the voltage range of 0.7-4.0 V at 20 °C and a high capacity retention (85% after 200 cycles at 1C).