Research and development on accelerator-driven transmutation system at JAERI

Japan Atomic Energy Research Institute carries out research and development on accelerator-driven system (ADS) to transmute minor actinides and long-lived fission products in high-level radioactive waste. The system is composed of high intensity proton accelerator, lead-bismuth spallation target and lead-bismuth cooled subcritical core with nitride fuel. About 2500 kg of minor actinide is loaded into the subcritical core. Annual transmutation amount using this system is 250 kg with 800 MW of thermal output. This transmutation amount corresponds to the amount of minor actinides produced from 10 units of 1GWe power reactors annually. A superconducting linear accelerator with the beam power of 20–30 MW is connected to drive the subcritical core. To maximize the transmutation efficiency, the nitride fuel without uranium, such as (Np, Am, Pu)N, is selected. The nitride fuel irradiated in the ADS is reprocessed by pyrochemical process followed by the re-fabrication of nitride fuel. Many research and development activities are under way and planned in the fields of subcritical core design, spallation target technology, lead-bismuth handling technology, accelerator development, and minor actinide fuel development. Especially, to study and evaluate the feasibility of the ADS from physics and engineering aspects, the transmutation experimental facility (TEF) is proposed under a framework of the High-Intensity Proton Accelerator Project.     

Embodied basis of invariant features in execution and perception of whole-body dynamic actions—knacks and focuses of Roll-and-Rise motion

This paper attempts to discover the invariant features in a whole-body dynamic task under perturbations. Our hypothesis is that the features are useful both for execution and recognition of a task, and have their origin in human embodiment.

For the sake of concreteness, we focus on a particular task named “Roll-and-Rise” motion, and carried out a multi-approach investigation. First, an analysis of motion capture data of human performance is presented to show its invariant features. Next, we show that such invariants emerge from the underlying physics of the task, using simulation data. These invariants are actually useful for generating robot motion, which has been successfully realized with an adult-size real humanoid robot. The experimental data are analyzed to confirm the temporal localization of invariant features. Lastly, we present a psychological experiment which confirms that these timings are actually important points where human observers extract crucial information about the task.     

Influence of x‐ray irradiation on doped europium in BaMgAl10O17 studied by x‐ray absorption fine structure and x‐ray diffraction

Abstract— We studied the influence of x‐ray irradiation on the doped europium ion in BaMgAl₁₀O₁₇ (BAM) by x‐ray absorption fine structure measurement and x‐ray diffraction. We found that x‐ray irradiation promoted oxidation of doped europium and fading emissions. However, no difference was found in x‐ray diffraction patterns before and after x‐ray irradiation. We concluded that the fading of BAM after x‐ray irradiation was mainly caused by oxidation of the doped europium in the BAM.     

Nickel–Silver Monotectic in Alumina Crucible for Use with Contact Thermometry

Previously, the authors have published work describing a pure Ni fixed point within alumina crucibles. The success of this study stimulated working with the Ni–Ag monotectic point in alumina crucibles. Similar to eutectic points, the Ni–Ag monotectic temperature is an invariant point but it differs from a eutectic reaction in such a way that the monotectic phase change takes place from Ni–Ag liquid solution to Ni–Ag solid solution and Ag rich Ni–Ag liquid solution. In the phase diagram references, the Ni–Ag monotectic phase transition temperature is assigned to be about 20 \(^{\circ }\)C below the pure Ni melting/freezing point. As is the case for pure Ni, mechanical stability is one of the concerns. Therefore, proper cell design is necessary to avoid breakage of the alumina crucible. The techniques used for the fabrication and measurement of the pure Ni cell were applied to the Ni–Ag cell as well. The cells have been successfully fabricated and the temperature measurement at the fixed point was carried out for more than 20 thermal cycles in total. A Pt/Pd thermocouple was used to measure the temperature and was calibrated from the tin point to the gold point to measure the ITS-90. Freezing plateaus are realized with the technique of “recurrent offset freezing method with reserved solid”. The duration of each freezing plateau is a minimum of 30 min. The monotectic transformation temperature for the best performed cell is determined as 1428.27 \(^{\circ }\)C with a combined uncertainty of ±0.06 \(^{\circ }\)C (\({k}=1\)).     

Scalable Design of Two‐Dimensional Oxide Nanosheets for Construction of Ultrathin Multilayer Nanocapacitor

Large size of capacitors is the main hurdle in miniaturization of current electronic devices. Herein, a scalable solution‐based layer‐by‐layer engineering of metallic and high‐κ dielectric nanosheets into multilayer nanosheet capacitors (MNCs) with overall thickness of ≈20 nm is presented. The MNCs are built through neat tiling of 2D metallic Ru_0.95O₂^0.2? and high‐κ dielectric Ca₂NaNb₄O₁₃^? nanosheets via the Langmuir–Blodgett (LB) approach at room temperature which is verified by cross‐sectional high‐resolution transmission electron microscopy (HRTEM). The resultant MNCs demonstrate a high capacitance of 40–52 µF cm^?2 and low leakage currents down to 10^?5–10^?6 A cm^?2. Such MNCs also possess complimentary in situ robust dielectric properties under high‐temperature measurements up to 250 °C. Based on capacitance normalized by the thickness, the developed MNC outperforms state‐of‐the‐art multilayer ceramic capacitors (MLCC, ≈22 µF cm^?2/5 × 10⁴ nm) present in the market. The strategy is effective due to the advantages of facile, economical, and ambient temperature solution assembly.     

Tropospheric ozone differential-absorption lidar using stimulated Raman scattering in carbon dioxide

A UV ozone differential-absorption lidar (DIAL) utilizing a Nd:YAG laser and a single Raman cell filled with carbon dioxide (CO(2)) is designed, developed, and evaluated. The generated wavelengths are 276, 287, and 299 nm, comprising the first to third Stokes lines of the stimulated Raman scattering technique. The correction terms originated from the aerosol extinction, the backscatter, and the absorption by other gases are estimated using a model atmosphere. The experimental results demonstrate that the emitted output energies were 13 mJ/pulse at 276 nm and 287 nm and 5 mJ/pulse at 299 nm, with pump energy of 91 mJ/pulse and a CO(2) pressure of 0.7 MPa. The three Stokes lines account for 44.0% of the available energy. The use of argon or helium as a buffer gas in the Raman cell was also investigated, but this leads to a dramatic decrease in the third Stokes line, which makes this wavelength practically unusable. Our observations confirmed that 30 min of integration were sufficient to observe ozone concentration profiles up to 10 km. Aerosol extinction and backscatter correction are estimated and applied. The aerosol backscatter correction profile using 287 and 299 nm as reference wavelengths is compared with that using 355 nm. The estimated statistical error is less than 5% at 1.5 km and 10% at 2.6 km. Comparisons with the operational carbon-iodine type chemical ozonesondes demonstrate 20% overestimation of the ozone profiles by the DIAL technique.     

Three-dimensional observation of connective tissue of bovine masseter muscle under concentrate- and roughage-fed conditions by using immunohistochemical/confocal laser-scanning microscopic methods

ABSTRACT:  We investigated changes in connective tissue components of masseter (MA) muscle in Japanese black heifers ( n = 6) in concentrate- and roughage-fed groups (groups C and R, respectively). Body weight, at slaughter, of experimental heifers in group C (272.3 ± 22.3 kg) was higher ( P < 0.05) than that of group R (213.8 ± 27.5 kg). However, muscle weight and myofiber diameter (superficial and deep layers) of MA muscle did not differ between groups C and R. In contrast, total mastication duration of group R was longer ( P < 0.05) than that of group C. MA muscle of groups C and R was composed only of type I myofiber. Using immunohistochemical/confocal laser-scanning microscopy, type I collagen was observed mainly in perimysium, and type V and VI collagen were observed in perimysium and endomysium of both groups. Type IV collagen and laminin were observed only in the endomysium in both groups. However, type III collagen and fibronectin were strongly apparent in the perimysium and endomysium in group R. Connective tissue components in the perimysium of groups C and R were observed to form plate-shaped layers. On the other hand, honeycomb-shaped connective tissue components were seen in the endomysium-surrounded muscle fibers. In particular, fibronectin was strongly observed in the perimysium and endomysium in group R. These results indicate that there are different developmental changes among connective tissue components in MA muscle in response to mastication. The immunohistochemical/confocal laser-scanning microscopic method is useful to investigate the structural relationship among connective tissue components in skeletal muscle.