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The lithium isotope effect in ionic superconductors is numerically investigated. Using first-principles and kinetic Monte–Carlo simulations, the diffusion coefficients of 6Li and 7Li ions are calculated. Two important effects that cause the difference in the mobilities of lithium isotopes are also shown: the quantum effect, which decreases the activation barrier energy for lithium ion in a certain structure and increases the ratio of the diffusion coefficient of Li isotopes, as well as the correlation effect between 6Li and 7Li ions and vacancies. These results will assist in finding materials that exhibit large lithium isotope effect. The preferred chemical composition of lithium isotopes required to enhance the lithium isotope effect and the application of these isotopes as a separation membrane for the lithium ionic superconductors are discussed.

We have performed the tritium release experiment on the fusion reactor blanket at JAEA/FNS since 2009, and then clarified the ratio of tritium release and the recovered tritium chemical form. In order to acquire the detailed tritium recovery performances, we have started a new blanket tritium recovery experiment with ionization chamber (IC) at JAEA/FNS. For the appropriate tritium measurement with IC, we improved the experimental container and carried out with an intense DT neutron source at JAEA/FNS. From our new experiment, the tritium recovery radioactivity from the LSC measurement corresponds with the calculation within 6%. However, it was pointed out that further improvement in the quantitative tritium measurement by IC method was needed.

We investigate isotope effects of lithium-ion diffusion in Lithium-ion conductors using ab initio computational methods in light of recently proposed novel lithium isotope separation technology based on ionic conductors. Using ab initio molecular dynamics simulations, we compute the diffusion coefficients D6(7) of 6Li+ (7Li+) in tetragonal Li7La3Zr2O12 and Li10GeP2S12 as a slow Li+-ion conductor and a fast Li+-ion conductor, respectively. We note that careful uncertainty estimations in the molecular dynamics simulations would be necessary to extract many-body effects on the diffusion coefficient ratio D6/D7 beyond the canonical value given by the transition-state theory. Numerical results for Li10GeP2S12 indicate that the isotope effect depends on the migration path. Specifically, the faster diffusion path along the c−axis exhibits a stronger isotope effect that is also temperature dependent, whereas the diffusion on the ab−plane shows a relatively weaker and temperature-independent effect. We introduce the probability distribution of the ionic displacement to reveal distinct differences in the ion-diffusion mechanism.

As a part of the Broader Approach activities, R&D on blanket related materials, reduced-activation ferritic martensitic (RAFM) steels as a structural material, SiCf/SiC composites for flow channel insert in the liquid blanket and/or use as advanced structural material, advanced tritium breeders and neutron multiplier, has been initiated directed at DEMO. As part of the RAFM steel mass production development, a 5 ton heat of RAFM steel (F82H) was procured by Electra Slag Re-melting as the secondary melting method, which was effective in controlling unwanted impurities. An 11 ton heat of EUROFER was also produced. For the SiCf/SiC composite development, NITE- and CVI-SiCf/SiC composites were prepared as reference materials and preliminary mechanical and physical properties were measured. Also compatibility tests between SiC and Pb-17Li have been prepared, related to the He-cooled Li-Pb blanket concept. For the beryllide neutron multiplayer Be-Ti alloy development, large size rods of about 30 mm diameter were fabricated successfully in EU. (C) 2011 Elsevier B.V. All rights reserved.