Application of energy-resolving neutron imaging to major-component analyses of materials using four-channel superconducting detector

Vu, TheDang*; Shishido, Hiroaki*; Aizawa, Kazuya; Oku, Takayuki; Oikawa, Kenichi; Harada, Masahide; Kojima, Kenji M*; Miyajima, Shigeyuki*; Soyama, Kazuhiko; Koyama, Tomio*; et al.

IEEJ Transactions on Electrical and Electronic Engineering, 19(11), p.1888 - 1894, 2024/11

https://doi.org/10.1002/tee.24144

Neutron transmission imaging system with a superconducting kinetic inductance detector

Vu, TheDang*; Shishido, Hiroaki*; Aizawa, Kazuya; Oku, Takayuki; Oikawa, Kenichi; Harada, Masahide; Kojima, Kenji M*; Miyajima, Shigeyuki*; Soyama, Kazuhiko; Koyama, Tomio*; et al.

Journal of Physics; Conference Series, 2776, p.012009_1 - 012009_9, 2024/06

https://doi.org/10.1088/1742-6596/2776/1/012009

Microbially formed Mn(IV) oxide as a novel adsorbent for removal of Radium

Tanaka, Kazuya; Yamaji, Keiko*; Masuya, Hayato*; Tomita, Jumpei; Ozawa, Mayumi*; Yamasaki, Shinya*; Tokunaga, Kohei; Fukuyama, Kenjin*; Ohara, Yoshiyuki*; Maamoun, I.*; et al.

Chemosphere, 355, p.141837_1 - 141837_11, 2024/05

https://doi.org/10.1016/j.chemosphere.2024.141837

In this study, biogenic Mn(IV) oxide was applied to remove Ra from mine water collected from a U mill tailings pond in the Ningyo-toge center. Just 7.6 mg of biogenic Mn(IV) oxide removed more than 98% of the Ra from 3 L of mine water, corresponding to a distribution coefficient of 10 mL/g for Ra at pH 7. The obtained value was convincingly high for practical application of biogenic Mn(IV) oxide in water treatment.

U(VI) sorption on illite in the presence of carbonate studied by cryogenic time-resolved laser fluorescence spectroscopy and parallel factor analysis

Mei, H.; Aoyagi, Noboru; Saito, Takumi*; Tanaka, Kazuya; Sugiura, Yuki; Tachi, Yukio

Applied Geochemistry, 162, p.105926_1 - 105926_8, 2024/02

https://doi.org/10.1016/j.apgeochem.2024.105926

Validation of the fast reactor plant dynamics analysis code Super-COPD using FFTF loss of flow without scram test #13

Hamase, Erina; Ohgama, Kazuya; Kawamura, Takumi*; Doda, Norihiro; Tanaka, Masaaki; Yamano, Hidemasa

Annals of Nuclear Energy, 195, p.110157_1 - 110157_14, 2024/01

https://doi.org/10.1016/j.anucene.2023.110157

To validate the fast reactor plant dynamics analysis code Super-COPD for the loss of flow without scram (LOFWOS) event, we participated in the IAEA benchmark for the LOFWOS test No.13 performed at the FFTF as one of the passive safety demonstration test. In the blind phase, there were challenges to reproduce outlet temperatures of fuel assemblies and the total reactivity. To improve the evaluation accuracy of them, the whole core model considering the radial heat transfer and interwrapper flow and the simplified assembly bowing reactivity model were introduced. As a result of the final phase, the second peak of outlet temperatures was reproduced successfully, and the total reactivity could generally follow the measured data. Super-COPD was validated for the LOFWOS event.

Orientation mapping of YbSn single crystals based on Bragg-dip analysis using a delay-line superconducting sensor

Shishido, Hiroaki*; Vu, TheDang*; Aizawa, Kazuya; Kojima, Kenji M*; Koyama, Tomio*; Oikawa, Kenichi; Harada, Masahide; Oku, Takayuki; Soyama, Kazuhiko; Miyajima, Shigeyuki*; et al.

Journal of Applied Crystallography, 56(4), p.1108 - 1113, 2023/08

https://doi.org/10.1107/S1600576723005204

Improved immobilization of Re(VII) from aqueous solutions bimetallic Ni/Fe nanoparticles; Implications towards Tc(VII) removal

Maamoun, I.; Tokunaga, Kohei; Dohi, Terumi; Kanno, Futoshi*; Falyouna, O.*; Eljamal, O.*; Tanaka, Kazuya

Frontiers in Nuclear Engineering (Internet), 2, p.1142823_1 - 1142823_17, 2023/03

https://doi.org/10.3389/fnuen.2023.1142823

Recently, the rapid development of nuclear power technologies and the continuous energy demand around the world exhibited massive amounts of contaminated water with radionuclides. Technetium-99 (Tc) is one of the long-lived radionuclides with a highly mobile anionic form (Tc(VII)) in aqueous solutions. Hence, the rapid and efficient Tc(VII) removal from radioactive water has emerged as a challenging issue. In this work, bimetallic nickel/iron nanoparticles (Ni/Fe) were prepared to enhance the immobilization of rhenium (Re(VII)) from aqueous solutions, as the surrogate of Tc(VII).

Improvement of the stability of IO-, SeO-, and SeO-coprecipitated barite after treatment with phosphate

Tokunaga, Kohei; Tanaka, Kazuya; Takahashi, Yoshio*; Kozai, Naofumi

Environmental Science & Technology, 57(8), p.3166 - 3175, 2023/02

https://doi.org/10.1021/acs.est.2c08939

Coprecipitation of radionuclides with barite has been studied to remove radionuclides from radioactive liquid waste because of its excellent removal efficiency; however, little information exists concerning the stability of the ions coprecipitated with barite. This study systematically investigated the stability of iodate, selenite, and selenate coprecipitated with barite via leaching tests. These oxyanions were gradually leached from the oxyanion-bearing barite into ultrapure water over time. Leaching of the oxyanions significantly increased in leaching solutions containing NaCl (pH5.3), NaNO (pH5.9), and NaSO (pH5.7). Conversely, leaching of the oxyanions was suppressed in KHPO solution (pH8.5), indicating that phosphate stabilized the oxyanion-bearing barite. The effect of phosphate treatment on oxyanion-bearing barite was further investigated. The results showed that the barite surface was modified with phosphate, and a thin surface layer of a barium phosphate-like structure was formed. The amount of oxyanions leached from the phosphate-treated samples into leaching solutions containing NaCl or NaNO was much lower than the amounts leached from the untreated barite samples into ultrapure water. The barite coprecipitation combined with subsequent phosphate treatment may be a promising method to efficiently remove iodate, selenite, and selenate from wastewater and stabilize them as barite coprecipitates.

Band gap opening in graphene by hybridization with Au (001) reconstructed surfaces

Terasawa, Tomoo; Matsunaga, Kazuya*; Hayashi, Naoki*; Ito, Takahiro*; Tanaka, Shinichiro*; Yasuda, Satoshi; Asaoka, Hidehito

Physical Review Materials (Internet), 7(1), p.014002_1 - 014002_10, 2023/01

https://doi.org/10.1103/PhysRevMaterials.7.014002

Au(001) surfaces exhibit a complex reconstructed structure [Hex-Au(001)] comprising a hexagonal surface and square bulk lattices, yielding a quasi-one-dimensional corrugated surface. When graphene was grown on this surface, the periodicity of the corrugated surface was predicted to change the electronic structure of graphene, forming bandgaps and new Dirac points. Furthermore, the graphene-Au interface is promising for bandgap generation and spin injection due to band hybridization. Here, we report the angle-resolved photoemission spectroscopy and density functional calculation of graphene on a Hex-Au(001) surface. The crossing point of the original and replica graphene bands showed no bandgap, suggesting that the one-dimensional potential was too small to modify the electronic structure. A bandgap of 0.2 eV was observed at the crossing point of the graphene and Au bands, indicating that the bandgap is generated using hybridization of the graphene and Au bands. We discussed the hybridization mechanism and concluded that the R30 configuration between graphene and Au and an isolated electronic structure of Au are essential for effective hybridization between graphene and Au. We anticipate that hybridization between graphene and Au would result in spin injection into graphene.

Extended X-ray absorption fine structure spectroscopy measurements and molecular dynamics simulations reveal the hydration structure of the radium(II) ion

Yamaguchi, Akiko; Nagata, Kojiro*; Kobayashi, Keita; Tanaka, Kazuya; Kobayashi, Toru; Tanida, Hajime; Shimojo, Kojiro; Sekiguchi, Tetsuhiro; Kaneta, Yui; Matsuda, Shohei; et al.

iScience (Internet), 25(8), p.104763_1 - 104763_12, 2022/08

https://doi.org/10.1016/j.isci.2022.104763

no abstracts in English