Bench-scale injection of magnesium hydroxide encapsulated iron nanoparticles (nFe@Mg(OH)) into porous media for Cr(VI) removal from groundwater

Maamoun, I.; Falyouna, O.*; Eljamal, R.*; Idham, M. F.*; Tanaka, Kazuya; Eljamal, O.*

Chemical Engineering Journal, 451, Part3, p.138718_1 - 138718_22, 2023/01

https://doi.org/10.1016/j.cej.2022.138718

Benchmark analysis of FFTF Loss of Flow Without Scram Test No.13 using fast reactor plant dynamics analysis code Super-COPD

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

Proceedings of 12th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS12) (Internet), 9 Pages, 2022/10

To improve the prediction accuracy of the plant dynamics analysis code named Super-COPD, JAEA has joined the IAEA benchmark for the FFTF Loss of Flow Without Scram Test No.13. In the first blind phase, there was the challenge to perform outlet temperatures of fuel assemblies more accurately. Hence, the renewed analysis was performed with the whole core multi-channel model in which each assembly was modelled to simulate the radial heat transfer among assemblies and the flow redistribution induced by the buoyancy in the NC conditions. Then, to validate the coupled transient analysis between the whole core multi-channel model and the one-point kinetics model, the analysis considering major reactivity feedbacks such as GEM, assembly bowing was performed. As a result, the second peak of outlet temperatures was reproduced successfully, and it was observed that the plant dynamics analysis could follow the measured data.

Rapid and efficient chromium (VI) removal from aqueous solutions using nickel hydroxide nanoplates (nNiHs)

Maamoun, I.; Bensaida, K.*; Eljamal, R.*; Falyouna, O.*; Tanaka, Kazuya; Tosco, T.*; Sugihara, Yuji*; Eljamal, O.*

Journal of Molecular Liquids, 358, p.119216_1 - 119216_13, 2022/07

https://doi.org/10.1016/j.molliq.2022.119216

Microbial influences on manganese deposit formation at Yunotaki Fall, Japan

Shiraishi, Fumito*; Chihara, Ryoji*; Tanimoto, Risa*; Tanaka, Kazuya; Takahashi, Yoshio*

Island Arc, 31(1), p.e12448_1 - e12448_9, 2022/05

https://doi.org/10.1111/iar.12448

At Yunotaki Fall in north Japan, manganese-oxidizing bacteria were previously assumed to have oxidized manganese to precipitate birnessite, which relied on oxygen released from algae. However, it remained unclear whether larger-scale manganese oxide precipitation was actually occurring under light conditions. This study evaluated the contribution of indirect oxidation using microelectrodes to analyze local water chemistry, in addition to bulk water chemistry and DNA analyses. The results of this study demonstrate that low bulk pH values in the hot spring water hindered indirect oxidation despite the occurrence of active oxygenic photosynthesis and that direct oxidation by manganese-oxidizing bacteria is considered to dominate in the investigated sample.

Effect of particle size on the colonization of biofilms and the potential of biofilm-covered microplastics as metal carriers

Wu, C.*; Tanaka, Kazuya; Tani, Yukinori*; Bi, X.*; Liu, J.*; Yu, Q.*

Science of the Total Environment, 821, p.153265_1 - 153265_9, 2022/05

https://doi.org/10.1016/j.scitotenv.2022.153265

Microplastics (MPs) with different particle sizes were co-cultured with a model freshwater fungus, strain KR21-2, to form biofilms on their surface. We also determined the changes in surface physicochemical properties of the biofilm-covered MPs (BMPs) and the heavy metal adsorption capacity of the original MPs and BMPs. The results revealed that the biofilms improve the adsorption of heavy metals on MPs, and the particle size of MPs plays a crucial role in biofilm colonization and adsorption of heavy metals by BMPs.

Insights into boron removal from water using Mg-Al-LDH; Reaction parameters optimization & 3D-RSM modeling

Eljamal, O.*; Maamoun, I.; Alkhudhayri, S.*; Eljamal, R.*; Falyouna, O.*; Tanaka, Kazuya; Kozai, Naofumi; Sugihara, Yuji*

Journal of Water Process Engineering (Internet), 46, p.102608_1 - 102608_13, 2022/04

https://doi.org/10.1016/j.jwpe.2022.102608

Synthesis of hybrid magnesium hydroxide/magnesium oxide nanorods [Mg(OH)/MgO] for prompt and efficient adsorption of ciprofloxacin from aqueous solutions

Falyouna, O.*; Bensaida, K.*; Maamoun, I.; Ashik, U. P. M.*; Tahara, Atsushi*; Tanaka, Kazuya; Aoyagi, Noboru; Sugihara, Yuji*; Eljamal, O.*

Journal of Cleaner Production, 342, p.130949_1 - 130949_15, 2022/03

https://doi.org/10.1016/j.jclepro.2022.130949

Sorption of Pu(IV) on biogenic Mn oxide and complexation of Pu(IV) with organic ligands secreted by fungal cells

Tanaka, Kazuya; Tani, Yukinori*; Kozai, Naofumi; Onuki, Toshihiko

Journal of Radioanalytical and Nuclear Chemistry, 331(2), p.1109 - 1114, 2022/02

https://doi.org/10.1007/s10967-021-08178-w

We investigated the sorption of Pu(IV) on biogenic Mn oxide produced by Mn(II)-oxidizing fungus. The sorption of Pu(IV) on biogenic Mn oxide was similar to that of U(VI) and different from that of Th(IV), possibly due to oxidation of Pu(IV) to Pu(VI). When Pu(IV) was sorbed on hyphae only, it was desorbed into the solution phase over time. Pu(IV) could be solubilized by complexation with organic ligands secreted by fungal cells. In particular, Pu(IV) desorption was observed under circumneutral pH conditions.

High spatial resolution neutron transmission imaging using a superconducting two-dimensional detector

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

IEEE Transactions on Applied Superconductivity, 31(9), p.2400505_1 - 2400505_5, 2021/12

https://doi.org/10.1109/TASC.2021.3111396

In this study, we employed a superconducting detector, current-biased kinetic-inductance detector (CB-KID) for neutron imaging using a pulsed neutron source. We employed the delay-line method, and high spatial resolution imaging with only four reading channels was achieved. We also performed wavelength-resolved neutron imaging by the time-of-flight method. We obtained the neutron transmission images of a Gd-Al alloy sample, inside which single crystals of GdAl were grown, using the delay-line CB-KID. Single crystals were well imaged, in both shapes and distributions, throughout the Al-Gd alloy. We identified Gd nuclei via neutron transmissions that exhibited characteristic suppression above the neutron wavelength of 0.03 nm. In addition, the Gd resonance dip, a dip structure of the transmission caused by the nuclear reaction between an isotope and neutrons, was observed even when the number of events was summed over a limited area of 15 m 12 m. Gd selective imaging was performed using the resonance dip of Gd, and it showed clear Gd distribution even with a limited neutron wavelength range of 1 pm.

Dynamics of radiocaesium within forests in Fukushima; Results and analysis of a model inter-comparison

Hashimoto, Shoji*; Tanaka, Taku*; Komatsu, Masabumi*; Gonze, M.-A.*; Sakashita, Wataru*; Kurikami, Hiroshi; Nishina, Kazuya*; Ota, Masakazu; Ohashi, Shinta*; Calmon, P.*; et al.

Journal of Environmental Radioactivity, 238-239, p.106721_1 - 106721_10, 2021/11

https://doi.org/10.1016/j.jenvrad.2021.106721

This study was aimed at analysing performance of models for radiocesium migration mainly in evergreen coniferous forest in Fukushima, by inter-comparison between models of several research teams. The exercise included two scenarios of countermeasures against the contamination, namely removal of soil surface litter and forest renewal, and a specific konara oak forest scenario in addition to the evergreen forest scenario. All the models reproduced trend of time evolution of radiocesium inventories and concentrations in each of the components in forest such as leaf and organic soil layer. However, the variations between models enlarged in long-term predictions over 50 years after the fallout, meaning continuous field monitoring and model verification/validation is necessary.