Controlling oxygen coordination and valence of network forming cations

Aoyagi, Takuya*; Kohara, Shinji*; Naito, Takashi*; Onodera, Yohei*; Kodama, Motomune*; Onodera, Taiga*; Takamatsu, Daiko*; Tahara, Shuta*; Sataka, Osami*; Miyake, Tatsuya*; et al.

Scientific Reports (Internet), 10, p.7178_1 - 7178_12, 2020/04

https://doi.org/10.1038/s41598-020-63786-y

Understanding the structure-property relationship of glass material is still challenging due to a lack of periodicity in disordered materials. Here, we report the properties and atomic structure of vanadium phosphate glasses characterized by reverse Monte Carlo modelling based on neutron/synchrotron X-ray diffraction and EXAFS data, supplemented by Raman and NMR spectroscopy. In vanadium-rich glass, the water durability, thermal stability and hardness improve as the amount of PO increases, and the network former of the glass changes from VO polyhedra to the interplay between VO polyhedra and PO tetrahedra. We find for the first time that the coordination number of oxygen atoms around a V is four, which is an unusually small coordination number, and plays an important role for water durability, thermal stability and hardness. Furthermore, we show that the similarity between glass and crystal beyond the nearest neighbor distance is important for glass properties. These results demonstrate that controlling the oxygen coordination and valence of the network-forming cation is necessary for designing the properties of glass.

Numerical simulation on self-leveling behavior of mixed particle beds using multi-fluid model coupled with DEM

Phan, L. H. S.*; Ohara, Yohei*; Kawata, Ryo*; Liu, X.*; Liu, W.*; Morita, Koji*; Guo, L.*; Kamiyama, Kenji; Tagami, Hirotaka

Proceedings of 12th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety (NUTHOS-12) (USB Flash Drive), 12 Pages, 2018/10

Self-leveling behavior of core fuel debris beds is one of the key phenomena for the safety assessment of core disruptive accidents (CDAs) in sodium-cooled fast reactors (SFRs). The SIMMER code has been developed for CDA analysis of SFRs, and the code has been successfully applied to numerical simulations for key thermal-hydraulic phenomena involved in CDAs as well as reactor safety assessment. However, in SIMMER's fluid-dynamics model, it is always difficult to represent the strong interactions between solid particles as well as the discrete particle characteristics. To solve this problem, a new method has been developed by combining the multi-fluid model of the SIMMER code with the discrete element method (DEM) for the solid phase to reasonably simulate the particle behaviors as well as the fluid-particle interactions in multi-phase flows. In this study, in order to validate the multi-fluid model of the SIMMER code coupled with DEM, numerical simulations were performed on a series of self-leveling experiments using a gas injection method in cylindrical particle beds. The effects of friction coefficient on the simulation results were investigated by sensitivity analysis. Though more extensive validations are needed, the reasonable agreement between simulation results and corresponding experimental data preliminarily demonstrates the potential ability of the present method in simulating the self-leveling behaviors of debris bed. It is expected that the SIMMER code coupled with DEM is a prospective computational tool for analysis of safety issues related to solid particle debris bed in SFRs.

Numerical simulation of solid-particle sedimentation behavior using a multi-fluid model coupled with DEM

Kawata, Ryo*; Ohara, Yohei*; Sheikh, Md. A. R.*; Liu, X.*; Matsumoto, Tatsuya*; Morita, Koji*; Guo, L.*; Kamiyama, Kenji; Suzuki, Toru

Proceedings of 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-17) (USB Flash Drive), 14 Pages, 2017/09

Feasible evaluation of neutron capture therapy for hepatocellular carcinoma using selective enhancement of boron accumulation in tumour with intra-arterial administration of boron-entrapped water-in-oil-in-water emulsion

Yanagie, Hironobu*; Kumada, Hiroaki*; Nakamura, Takemi; Higashi, Shushi*; Ikushima, Ichiro*; Morishita, Yasuyuki*; Shinohara, Atsuko*; Fujiwara, Mitsuteru*; Suzuki, Minoru*; Sakurai, Yoshinori*; et al.

Proceedings of 14th International Congress on Neutron Capture Therapy (ICNCT-14) (CD-ROM), p.157 - 160, 2010/10

Design Study on Sodium-Cooled Large-Scale Reactor

Murakami, Tsutomu; Hishida, Masahiko; Kisohara, Naoyuki; Hayafune, Hiroki; Hori, Toru; Fujii, Tadashi; Uchita, Masato; Chikazawa, Yoshitaka; Uno, Osamu; Saigusa, Toshiie; et al.

JNC TY9400 2004-014, 78 Pages, 2004/07

JNC-TY9400-2004-014.pdf:7.97MB

This report summarizes the results of the design study on the sodium-cooled large-scale reactor performed in JFY2003, which is the third year of Phase 2. In the JFY2003 design study, critical subjects related to safety, structural integrity and thermal hydraulics which found in the last fiscal year has been examined and the plant concept has been modified. Furthermore, fundamental specifications of main systems and components have been set and economy has been evaluated. In addition, as the interim evaluation of the candidate concept of the FBR fuel cycle is to be conducted, cost effectiveness and achievability for the development goal were evaluated and the data of the three large-scale reactor candidate concepts were prepared.

Evaluation on fretting wear of heat-transfer tubes of Primary Sodium Mechanical Pump installed in IHX Component (3); Vibration Analysis Model and 1/4-Scale Vibration Test Equipment

Kisohara, Naoyuki; Soman, Yoshindo; Nishiguchi, Yohei; Konomura, Mamoru

JNC TN9400 2003-090, 76 Pages, 2003/10

JNC-TN9400-2003-090.pdf:4.4MB

The conceptual design study of sodium-cooled FBRs is in progress in the "Feasibility Study on Commercialized Fast Reactor Cycle Systems (F/S)". In this plant system design, a primary sodium pump are placed into an intermediate heat exchanger (IHX) and these two components are installed in one vessel to reduce plant construction cost. The primary sodium pump is located in the center of IHX tube bundle and this pump-IHX component includes primary/secondary sodium flow shrouds, pump-IHX boundary shroud and bellows. Although the pump and IHX are installed in the same vessel, these two components are structurally separated, because they are connected through a bellows and their weights are supported by different floors. However, the vibration caused by pump rotation has possibility to induce the vibration of heat transfer tubes via sodium and it leads the tubes to fretting wear against their support plates. Therefore, the tube fretting wear has been evaluated by both a simple beam vibration analysis model and a detailed shell vibration analysis model. Since the pump-IHX component consists of many different parts such as shrouds and tube bundle, analysis tools cannot reveal the vibration phenomena precisely. Then the analysis model requires to be validated by vibration tests. A 1/4-scale vibration test equipment of the whole pump-IHX component has been planned to confirm the occurrence and transmission of vibration. This test equipment is precisely minimized based on the actual pump-IHX component structure except the tube bundle. Acceleration sensors are installed on the shrouds to measure beam and shell vibration phenomena, and the signal will be used to reveal vibration modes and pump response properties. The fabrication of the test equipment was completed in FY2002 except the pump. In FY2003 the vibration tests are being executed by using electromagnetic vibrator instead of the pump. In FY2005, the pump will be settled into the test equipment, and the vibration tes

Design Study on Sodium-Cooled Large-Scale Reactor

Kisohara, Naoyuki; Hishida, Masahiko; Nibe, Nobuaki; Hori, Toru; Fujii, Tadashi; Uchita, Masato; Chikazawa, Yoshitaka; Saigusa, Toshiie; Uno, Osamu; Soman, Yoshindo; et al.

JNC TY9400 2003-014, 52 Pages, 2003/09

JNC-TY9400-2003-014.pdf:3.12MB

In Phase 2 of the F/S, it is planed to precede a preliminary conceptual design of a sodium-cooled large-scale reactor based on the design of the advanced loop type reactor. Through the design study, it is intended to construct such a plant concept that can show its attraction and competitiveness as a commercialized reactor. This report summarizes the results of the design study on the sodium-cooled large-scale reactor performed in JFY2002, which is the second year of Phase 2. In the JFY2002 design study, critical subjects related to safety, structural integrity and thermal hydraulics which found in the last fiscal year has been examined and the plant concept has been modified. Furthermore, fundamental specifications of main systems and components have been set and economy has been evaluated.As a result of this study, the plant concept of the sodium-cooled large-scale reactor has been constructed, which has a prospect to satisfy the economic goal (construction cost: less than 200,000yens/kWe, etc.) and has a prospect to solve the critical subjects.

Numerical simulation of mixed particle sedimentation using a particle-grid coupled method

Kawata, Ryo*; Ohara, Yohei*; Fujimoto, Takuya*; Nishida, Satoshi*; Morita, Koji*; Guo, L.*; Tagami, Hirotaka; Suzuki, Toru

no journal, , 

no abstracts in English

Geo-fluid analysis of the natural purification mechanism of Yotsugi mill tailings pond

Kawasaki, Yohei*; Granata, G.*; Tokoro, Chiharu*; Ohara, Yoshiyuki

no journal, , 

Arsenic in mine wastewater is an important issue in environmental research. In this study, to better understand the phenomena involved in the removal of arsenic from wastewater, the dynamic behavior of arsenic in the Yotsugi Mill Tailings Pond at Ningyo-toge mine was investigated. By utilizing geosphere fluid modeling software (GETFLOWS), we first reproduced the overall area flow through the advection-dispersion of non-reactive silicate ion with assuming the groundwater inlet. Following this, the total concentrations of arsenic and iron were reproduced by including in the previous advection-dispersion model, the first order kinetics for oxidation of As(III) and Fe(II) along with the precipitation equilibrium of Fe(III) as ferrihydrite. Finally, the adsorption of As(V) or As(III) on ferrihydrite was included in the simulation by considering the surface complexation model previously validated in batch adsorption tests. The results highlighted the natural oxidation of Fe(II) to Fe(III) and the subsequent precipitation of Fe(III) as ferrihydrite. Furthermore, the as-precipitated ferrihydride exhibited a strong ability to remove the arsenic by adsorption. The results also emphasized that the oxidation of As(III) to As(V) and the competitive adsorption between arsenic and the natural phosphates in water, play a key role in the natural removal of the arsenic in the pond.

DNP and SANS studies of the structures of spurs, blobs, and tracks

Kumada, Takayuki; Noda, Yohei; Hashimoto, Takeji; Koizumi, Satoshi; Ishikawa, Norito; Ohara, Kota

no journal, , 

We tried to determine distribution of radicals produced by radiolysis of polymer materials using techniques of dynamic nuclear polarization and small-angle neutron scattering.