Heterogeneity effects in micro-beam XRF scanning spectroscopy of binary powdered mixtures and lake sediments

Katsuta, Nagayoshi*; Umemura, Ayako*; Naito, Sayuri*; Masuki, Yuma*; Itayama, Yui*; Niwa, Masakazu; Shirono, Shinichi*; Yoshida, Hidekazu*; Kawakami, Shinichi*

Spectrochimica Acta, Part B, 210, p.106817_1 - 106817_11, 2023/12

https://doi.org/10.1016/j.sab.2023.106817

X-ray fluorescence (XRF) scanning of lacustrine sediments has been used to extend the approach to a wider range of elemental records in both ages and timescales of variations in past environments and climates. However, one of severe problems with effects of the XRF intensity by grain size and mineralogical composition known as "heterogeneity effects" have been pointed out. This study investigated the heterogeneity effect of Fe intensities on X-ray beam using several binary powder mixtures and lacustrine sediment cores.

Identification of advanced spin-driven thermoelectric materials via interpretable machine learning

Iwasaki, Yuma*; Sawada, Ryoto*; Stanev, V.*; Ishida, Masahiko*; Kirihara, Akihiro*; Omori, Yasutomo*; Someya, Hiroko*; Takeuchi, Ichiro*; Saito, Eiji; Yorozu, Shinichi*

npj Computational Materials (Internet), 5, p.103_1 - 103_6, 2019/10

https://doi.org/10.1038/s41524-019-0241-9

Flexible heat-flow sensing sheets based on the longitudinal spin Seebeck effect using one-dimensional spin-current conducting films

Kirihara, Akihiro*; Kondo, Koichi*; Ishida, Masahiko*; Ihara, Kazuki*; Iwasaki, Yuma*; Someya, Hiroko*; Matsuba, Asuka*; Uchida, Kenichi*; Saito, Eiji; Yamamoto, Naoharu*; et al.

Scientific Reports (Internet), 6, p.23114_1 - 23114_7, 2016/03

https://doi.org/10.1038/srep23114

Heat-flow sensing is expected to be an important technological component of smart thermal management in the future. Conventionally, the thermoelectric (TE) conversion technique, which is based on the Seebeck effect, has been used to measure a heat flow by converting the flow into electric voltage. However, for ubiquitous heat-flow visualization, thin and flexible sensors with extremely low thermal resistance are highly desired. Recently, another type of TE effect, the longitudinal spin Seebeck effect (LSSE), has aroused great interest because the LSSE potentially offers favourable features for TE applications such as simple thin-film device structures. Here we demonstrate an LSSE-based flexible TE sheet that is especially suitable for a heat-flow sensing application. This TE sheet contained a NiZnFeO film which was formed on a flexible plastic sheet using a spray-coating method known as ferrite plating. The experimental results suggest that the ferrite-plated film, which has a columnar crystal structure aligned perpendicular to the film plane, functions as a unique one-dimensional spin- current conductor suitable for bendable LSSE-based sensors. This newly developed thin TE sheet may be attached to differently shaped heat sources without obstructing an innate heat flux, paving the way to versatile heat-flow measurements and management.

Study on steam generator tube wastage mechanism by liquid droplet impingement erosion; Temperature and pressure measurement of two-phase free jet

Yoshida, Atsuro*; Higashi, Yuma*; William, K.*; Arae, Kunihiko*; Narabayashi, Tadashi*; Tsuji, Masashi*; Ohshima, Hiroyuki; Kurihara, Akikazu

no journal, , 

It may occur heat transfer tube failure event in steam generator of sodium-cooled fast reactor. Sodium reacts vigorously with water in the case of water leakage into sodium, the neighboring tubes are damaged by sodium-water reaction jet, tube wastage could arise from the effect of erosion and corrosion. The wastage phenomena remains to be fully elucidated by its complexity. In this study, the authors carried out the measurement experiment of temperature and pressure distribution in two-phase free jet and analyzed the wastage quantitatively from the standpoint of erosion effect.

Tritium production and containment performance of lithium rod test module for high temperature gas-cooled reactor

Ida, Yuma*; Matsuura, Hideaki*; Nagasumi, Satoru*; Katayama, Kazunari*; Otsuka, Teppei*; Goto, Minoru; Nakagawa, Shigeaki

no journal, , 

JAEA and Kyushu University have studied the tritium production method using high temperature gas-cooled reactors (HTGR) for initial fusion reactors. In this method, lithium compounds are loaded into the reactor core and tritium is produced with Li(n,)T reaction. We studied about optimization of lithium loading method, effective tritium containment method and nuclear thermal design of lithium loaded HTGR, and consequently we confirmed the feasibility of the tritium production method. Then, we started preliminary study for lithium irradiation experiment by test reactors. This paper describes evaluation results of tritium production and tritium containment for proposed lithium irradiation capsule.

Study on tritium confinement method using Li rod with Zr in very high temperature gas-cooled reactor; Hydrogen storage properties of Zr in high temperature (700850C) conditions

Okamoto, Ryo*; Matsuura, Hideaki*; Ida, Yuma*; Koga, Yuki*; Katayama, Kazunari*; Otsuka, Teppei*; Goto, Minoru; Nakagawa, Shigeaki; Ishitsuka, Etsuo; Nagasumi, Satoru; et al.

no journal, , 

Currently, many researches to achieve DT nuclear-fusion power generation are under proceeding but the method to provide initial tritium loaded to fusion prototype reactor is not clear. The method of tritium production by using high temperature gas-cooled reactor (HTGR) was proposed. In this method, lithium rods are loaded to the reactor core of HTGR and tritium is produced by Li(n,)T reaction. And the method to reduce the spilled tritium by using the lithium rod with zirconium layer was proposed. In this study, the experiments to evaluate the performance of hydrogen absorption in the zirconium layer were conducted under the temperature condition more than 700C which is the normal operation condition for the very high temperature gas-cooled reactor (VHTR). The experimental result concerning solubility and diffusion factor of hydrogen in the zirconium layer will be presented and discussed.

Study on tritium confinement method using Li rod with Zr in HTGR; Hydrogen absorption properties of Zr in high temperature (700-900C) conditions

Okamoto, Ryo*; Matsuura, Hideaki*; Ida, Yuma*; Koga, Yuki*; Suganuma, Takuro*; Katayama, Kazunari*; Otsuka, Teppei*; Goto, Minoru; Nakagawa, Shigeaki; Ishitsuka, Etsuo; et al.

no journal, , 

It has been proposed that lithium rods, which are cylindrical lithium compounds, are loaded into a HTGR and tritium for initial fusion reactors is produced by Li(n,)T reaction. In this study, it was discussed that the lithium rods are covered with zirconium layers to prevent the produced tritium leak. The solubility and diffusion coefficient of hydrogen in zirconium were measured and the effectiveness of the zirconium layers on prevention of tritium leakage was estimated with the measured values. As a result, the tritium leakage ratio with the zirconium layers was estimated two orders lower than that without the zirconium layers, and hence it was considered that the zirconium layer is very effective on the prevention of the tritium leakage.

The Influence of hydrogen absorption performance of Zr on tritium confinement properties of Li rod in HTGR

Okamoto, Ryo*; Matsuura, Hideaki*; Ida, Yuma*; Koga, Yuki*; Katayama, Kazunari*; Otsuka, Teppei*; Goto, Minoru; Nakagawa, Shigeaki; Ishitsuka, Etsuo; Nagasumi, Satoru

no journal, , 

A study on tritium production using a high-temperature gas-cooled reactor has been carried out and it was proposed that zirconium is loaded into the lithium irradiation capsule to confine tritium within the irradiation capsule under high temperature condition. In this study, zirconium loading method was examined by numerical calculations to improve the tritium confinement. As a result, it was found that improvement in the tritium confinement can be expected by loading spherical zirconium into the irradiation capsule.

Development of nonlinear seismic response analysis model of human body considering individual differences

Takada, Tsuyoshi; Matsumoto, Yuma*; Hida, Takenori*; Itoi, Tatsuya*

no journal, , 

no abstracts in English

Computer simulation of the earliest processes of radiation biological effects of; Direct and indirect effects of DNA damage

Kai, Takeshi; Toigawa, Tomohiro; Matsuya, Yusuke; Hirata, Yuho; Tezuka, Tomoya*; Tsuchida, Hidetsugu*; Ito, Yuma*; Yokoya, Akinari*

no journal, , 

Irradiation of living systems forms complex DNA damage that induces biological effects in very rare cases. This complex DNA damage is called cluster damage and is very difficult to detect experimentally. In this study, we have developed physical and chemical codes for analyzing DNA damage, and are working to elucidate the formation mechanism of cluster damage. In this study, we analyzed the results of calculations in a simple system in which energy is deposited to DNA and secondary electrons are emitted, and showed that the formation mechanism of cluster damage strongly depends on the deposition energy to DNA. This scientific insight is expected to contribute to the elucidation of the repair mechanism of DNA damage and lead to the elucidation of radiation biological effects.