Supposed existence of Np4+ in a genuine dissolver solution from the results of extraction simulation by PARC-L code

With a genuine spent fuel solution (a dissolver solution), a laboratory-scale reprocessing experiment of an extraction–separation process was performed using mixer-settlers as extractors. In the experiment, n-butyraldehyde was utilized as a reducing reagent of Np^(VI)O₂²⁺ to Np^(V)O₂⁺ for the purpose to distinguish Np^(VI)O₂²⁺ from Np⁴⁺. From the Np concentration in the aqueous phase, Np would be extracted from the dissolver solution together with U and Pu. The scrutiny of Np behavior was performed utilizing 66 cases of calculation results by a Japan Atomic Energy Agency open extraction simulation code, the Program for Advanced Extraction with Radiation Effect Calculation–Lightened version. From the scrutiny, the authors found that the calculation result with 60% of Np⁴⁺ in the dissolver solution represented the best experimental extraction–separation behavior of Np. Therefore, it was supposed that the dissolver solution contained sufficient proportion of Np⁴⁺ to affect the extraction–separation behavior of Np.     

RIKEN isotope separator on-line GARIS/IGISOL

This paper describes the fabrication and the characteristics of an isotope separator on-line (ISOL) which was constructed at the RIKEN Ring Cyclotron Facility. The ISOL consists of a gas-filled recoil separator and an ion-guide isotope separator on-line. Because of this combination the ISOL enables us to study short-lived isotopes of almost all elements.     

Experimental verification of the fast reactor safety analysis code SIMMER-III for transient bubble behavior with condensation

Experimental verification of a reactor safety analysis code, SIMMER-III, was undertaken for transient behaviors of large-scale bubbles with condensation. The present study aimed to verify the code for numerical simulations of relatively short-time-scale multi-phase, multi-component hydraulic problems. Among these, vaporization and condensation, or simultaneous heat and mass transfer, play important roles. In this study, a series of transient bubble behavior experiments dedicated to condensation phenomena with noncondensable gases was carried out. In the experiments, a pressurized mixture of noncondensable gas and steam was discharged as a large-scale single bubble into a cylindrical pool filled with stagnant subcooled water. The concentration of noncondensable gas was taken as an experimental parameter as was the species of noncondensable gas. The characteristics of transient behavior of large-scale bubbles with condensation observed in the experiments were estimated through experimental analyses using SIMMER-III. In the experiments with steam condensation, dispersion of the gas mixture discharged into the liquid pool was accompanied by vapor condensation at the bubble surface. SIMMER-III simulations suggested that the noncondensable gas had a less inhibiting effect on the condensation of large-scale bubbles. This is a different characteristic to that of the quasi-steady condensation of small-scale bubbles observed in our previous experiments.     

Structural and functional correlates of synaptic transmission in the vertebrate neuromuscular junction

Because vertebrate neuromuscular junctions are readily accessible for experimental manipulation, they have provided a superb model in which to examine and test functional correlates of chemical synaptic transmission. In the neuromuscular synapse, acetylcholine receptors have been localized to the crests of the junctional folds and visualized by a variety of ultrastructural techniques. By using ultrarapid freezing techniques with a temporal resolution of less than 1 msec, quantal transmitter release has been correlated with synaptic vesicle exocytosis at discrete sites called “active zones.” Mechanisms for synaptic vesicle membrane retrieval and recycling have been identified by using immunological approaches and correlated with endocytosis via coated pits and coated vesicles. In this review, available ultrastructural, physiological, immunological, and biochemical data have been used to construct an ultrastructural model of neuromuscular synaptic transmission that correlates structure and function at the molecular level.     

Effects of an alloying element on a c-component loop formation and precipitate resolution in Zr alloys during ion irradiation

It is important to clarify the mechanisms of the dislocation loop formation, dissolution of precipitates to understand the degradation behavior of the fuel cladding tubes in light water reactors (LWR) under neutron irradiation. In this study, 3.2 MeV Ni ion irradiation was carried out at 400°C on Zircaloy-2 and two types of model alloys with and without Fe (Zr-1.5Sn-0.3Fe and Zr-1.5Sn). To understand the effects of hydrogen, 60 and 300 ppm pre-injected Zircaloy-2 samples were also irradiated. The microstructure was observed with a conventional transmission electron microscopy. Additionally, the dissolution of precipitates and the enrichment of the alloying element due to irradiation were analyzed using a spherical aberration (Cs)-corrected high-resolution analytical electron microscope. After ion irradiation at 400°C, the dissolution of Fe-enriched precipitates and the c-component dislocation loops were observed in the region of peak ion damage. Observations by STEM-EDS showed that Fe atoms were enriched in the c-component dislocation loops. On the contrary, the c-component dislocation loops were detected in Fe-containing alloys (Zircaloy-2 and Zr-1.5Sn-0.3Fe alloy) but were not in the Zr-1.5Sn alloy. These results indicate that the dissolution of Fe-enriched precipitates and the enhanced formation of c-component dislocation loops are essential for the degradation of LWR fuel cladding under irradiation.     

Binding of heavy metal ions by chemically modified woods

Three chemically modified woods were prepared and used for the binding of heavy metal ions. Wood–polythylenimine composite (wood–PEI) was found to be effective for the adsorption of heavy metal ions such as Hg²⁺, Cu²⁺, and other metal ions which tend to form stable ammine complexes. Adsorption of metal ions on a wood–PEI derivative containing dithiocarbamate group (DTC–wood) was higher than that by wood–PEI. Especially, the reactivity of DTC–wood with Hg²⁺ was quite high and the binding capacity of about 5 mmol/g was easily attainable. The rate of adsorption on these wood-based adsorbents was very high, and adsorption of about 70% of total binding capacity was accomplished in the first 1 h. This may be due to a highly porous structure and a hydrophilic nature of the wood which constitutes the skeleton of the adsorbents. Amidoximated wood (AO–wood) prepared by the reaction of cyanoethylated wood with hydroxylamine showed selective adsorptivity for uranium in sea water. More than 53% of uranium in the sea water used was adsorbed by the AO–wood.     

GaInP/AlGaInP double-heterostructure laser grown on a(111)B-oriented GaAs substrate by metalorganic chemical vapourdeposition

Room temperature continuous-wave operation of a Ga_0.5In _0.5P/(Al_0.5Ga_0.5)_0.5In _0.5P double-heterostructure laser grown on a (111)B-oriented GaAs substrate by metalorganic chemical vapour deposition was obtained for the first time. The threshold current was 99 mA. The emission wavelength was around 650 nm, which was about 30 nm shorter than that of a similar laser grown on a (100)-oriented GaAs substrate     

Influence of proteoglycan contents and of tissue hydration on the frictional characteristics of articular cartilage

In this work, the hypothesis that water content and substances present on the articular surface play an important role in lubrication through the formation of a layer with a high content of water on the articular surface is analysed. The hydrophilic properties of proteoglycans exposed at the articular surface and hydration of tissue are the main responsible factors for the formation of this layer. The role of the articular surface in the frictional characteristics of articular cartilage was examined using specimens (femoral condyles of pigs) with intact and wiped surfaces tested in intermittent friction tests. Results indicated that the intact condition presented low friction in comparison with the wiped condition. The measured water loss of the articular cartilage after sliding and loading indicated a gradual decrease in the water content as the time evolved, and rehydration was observed after the submersion of unloaded specimens in the saline bath solution. Micrographic analyses indicated the presence of a layer covering the articular surface, and histological analyses indicated the presence of proteoglycans in this superficial layer. The hydration of the cartilage surface layer and proteoglycan in this layer influence lubrication.     

Development of post-processor approach for an industrial robot FANUC R2000<Emphasis Type="Italic">i</Emphasis>C

In this paper, a post-processor for the industrial robot FANUC R2000iC is introduced. Without going through the conventional teaching process, the post-processor regularly generates a rigorous robotic program from cutter location source data called CLS data. The CLS data are easily made through the main process of CAD/CAM, so that a promising data interface is realized between the industrial robot and CAD/CAM. The effectiveness is evaluated through simulations of trajectory following and also through an actual machining experiment of foamed polystyrene with a complex shape.     

Mass measuring instrument for use under microgravity conditions

A prototype instrument for measuring astronaut body mass under microgravity conditions has been developed and its performance was evaluated by parabolic flight tests. The instrument, which is the space scale, is applied as follows. Connect the subject astronaut to the space scale with a rubber cord. Use a force transducer to measure the force acting on the subject and an optical interferometer to measure the velocity of the subject. The subject's mass is calculated as the impulse divided by the velocity change, i.e., M=integral Fdt/delta v. Parabolic flight by using a jet aircraft produces a zero-gravity condition lasting approximately 20 s. The performance of the prototype space scale was evaluated during such a flight by measuring the mass of a sample object.