The Development of non-destructive assay technology for the quantification of nuclear material in high active solid waste; Overview of the collaborative research using neutron measurement techniques by the Japan Atomic Energy Agency and the U.S. Department of Energy

Shirafuji, Masaya; Sano, Kyohei; Horiuchi, Masakazu; Kato, Akane; Watanabe, Kazuki; Tanigawa, Masafumi; Maruyama, Hajime; Kitao, Takahiko; Conner, J.*; LaFleur, A.*; et al.

Dai-46-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2025/12

In situ reaction and alteration of mudstone-cement interfaces at the Horonobe URL; Comparison between ordinary Portland cement and low alkaline cement

Dei, Shuntaro; Shibata, Masahito*; Negishi, Kumi*; Sugiura, Yuki; Amano, Yuki; Bateman, K.*; Wilson, J.*; Yokoyama, Tatsunori; Kagami, Saya; Takeda, Masaki; et al.

Results in Earth Sciences (Internet), 3, p.100097_1 - 100097_16, 2025/12

https://doi.org/10.1016/j.rines.2025.100097

Interactions between cement and host rock in geological repositories for radioactive waste will result in a chemically disturbed zone, which may potentially affect the long-term safety. This paper investigates the chemical evolution at the interface between cement (Ordinary Portland Cement: OPC and Low Alkaline Cement: LAC) and mudstone after 11 years of in situ reactions at the Horonobe Underground Research Laboratory. The study combines various analytical techniques to identify the key reactions at the cement-rock interface, including cement dissolution, precipitation of secondary minerals such as calcite and C-(A-)S-H phases, cation exchange in montmorillonite and reduced porosity in mudstone. The study also highlights the effects of cement-mudstone interactions on radionuclide migration, such as reduction of diffusivity due to reduced porosity and enhancement of sorption due to incorporation into secondary minerals in the altered mudstone.

Upper limit for the Cm(Ti,xn)Og reaction cross section

Gall, B. J.-P.*; Asai, Masato; Ito, Yuta; Toyoshima, Atsushi*; 30 of others*

Journal of the Physical Society of Japan, 94(9), p.094201_1 - 094201_9, 2025/09

https://doi.org/10.7566/JPSJ.94.094201

An experiment to search for Og isotopes using the Ti beam impinging on Cm target was performed at RIKEN Nishina Center. The optimal beam energy was determined from the quasielastic barrier distribution extracted from the excitation function of quasielastic backscattering. As a result, no Og decay was found, enabling only an estimation of the sensitivity for one event of 0.27 pb, and the 1 cross section upper limit of 0.50 pb.

Effects of the hydration states of water molecules on the mechanical properties of dual movable cross-linked polymeric gels

Kawai, Yusaku*; Park, J.*; Motokawa, Ryuhei; Ikura, Ryohei*; Murayama, Shunsuke*; Yamaoka, Kenji*; Fujii, Yoshihisa*; Ikemoto, Yuka*; Tanaka, Masaru*; Matsuba, Go*; et al.

ACS Applied Polymer Materials (Internet), 7(12), p.7767 - 7776, 2025/06

https://doi.org/10.1021/acsapm.5c00270

Magnetism of kagome metals (FeCo)Sn studied by SR

Cai, Y.*; Yoon, S.*; Sheng, Q.*; Zhao, G.*; Seewald, E. F.*; Ghosh, S.*; Ingham, J.*; Pasupathy, A. N.*; Queiroz, R.*; Lei, H.*; et al.

Physical Review B, 111(21), p.214412_1 - 214412_17, 2025/06

https://doi.org/10.1103/PhysRevB.111.214412

A Review on the effect of iron on bentonite stability

Wilson, J.*; Sasamoto, Hiroshi; Tachi, Yukio; Kawama, Daisuke*

Applied Clay Science, 275, p.107862_1 - 107862_15, 2025/05

https://doi.org/10.1016/j.clay.2025.107862

High-Level Radioactive Waste (HLW) repositories include iron or steel-based containers/overpack and bentonite buffers. Over the last 25 years or so, research efforts have attempted to elucidate the nature of iron-bentonite interactions, especially the potential for the deleterious alteration of the swelling clay component (smectite), to iron-rich layer silicates, some of which lack the capacity for intracrystalline swelling. This could result in a reduction or loss in swelling pressure in the bentonite buffer which is designed to protect waste containers from shear forces and also acts to restrict water and solute transport, as part of an engineered barrier system. Most data on iron-bentonite interactions come from experimental and geochemical modelling studies, as natural analogue data are lacking. The data suggests that there is the potential for the development of an iron-rich bentonite alteration zone with smectite (generally present as the aluminous montmorillonite type) undergoing alteration to iron-rich solids, including layer silicates and steel corrosion products such as green rust or magnetite. The evidence available is complex, arguably incomplete, with many potential complex couplings. Many uncertainties remain despite efforts taken over the last 25 years, but plausible scenarios for iron-bentonite interactions have been identified and possible implications for buffer properties have been suggested.

Synthesis of BaSiH hydridosilicate at high pressures; A Bridge to BaSiH polyhydride

Beyer, D. C.*; Spektor, K.*; Vekilova, O. Y.*; Grins, J.*; Barros Brant Carvalho, P. H.*; Leinbach, L. J.*; Sannemo-Targama, M.*; Bhat, S.*; Baran, V.*; Etter, M.*; et al.

ACS Omega (Internet), 10(15), p.15029 - 15035, 2025/04

https://doi.org/10.1021/acsomega.4c10502

Hydridosilicates featuring SiH octahedral moieties represent a rather new class of compounds with potential properties relating to hydrogen storage and hydride ion conductivity. Here, we report on the new representative BaSiH obtained from reacting the Zintl phase hydride BaSiH with H fluid at pressures above 4 GPa and subsequent decompression to ambient pressure. It consists of complex SiH ions, which are octahedrally coordinated by Ba counterions. The arrangement of Ba and Si atoms deviates only slightly from an ideal fcc NaCl structure. IR and Raman spectroscopy showed SiH bending and stretching modes in the ranges 800-1200 and 1400-1800 cm, respectively. BaSiH is thermally stable up to 95C above which decomposition into BaH and Si takes place. DFT calculations indicated a direct band gap of 2.5 eV. The discovery of BaSiH consolidates the compound class of hydridosilicates, accessible from hydrogenations of silicides at gigapascal pressures (10 GPa). The structural properties of BaSiH suggest that it presents an intermediate (or precursor) for further hydrogenation at considerably higher pressures to the predicted superconducting polyhydride BaSiH.

Competition between mass-symmetric and asymmetric fission modes in Md produced in the He + Es reaction

Nishio, Katsuhisa; Hirose, Kentaro; Makii, Hiroyuki; Orlandi, R.; Kean, K. R.*; Tsukada, Kazuaki; Toyoshima, Atsushi*; Asai, Masato; Sato, Tetsuya; Chiera, N. M.*; et al.

Physical Review C, 111(4), p.044609_1 - 044609_12, 2025/04

https://doi.org/10.1103/PhysRevC.111.044609

Neutron transmission measurements for silica glass at the KURNS-LINAC

Lee, J.; Rossi, F.; Kodama, Yu; Hironaka, Kota; Koizumi, Mitsuo; Sano, Tadafumi*; Matsuo, Yasunori*; Hori, Junichi*

Annals of Nuclear Energy, 211, p.111017_1 - 111017_7, 2025/02

https://doi.org/10.1016/j.anucene.2024.111017

Gyro-spintronic material science using vorticity gradient in solids

Nozaki, Yukio*; Sukegawa, Hiroaki*; Watanabe, Shinichi*; Yunoki, Seiji*; Horaguchi, Taisuke*; Nakayama, Hayato*; Yamanoi, Kazuto*; Wen, Z.*; He, C.*; Song, J.*; et al.

Science and Technology of Advanced Materials, 26(1), p.2428153_1 - 2428153_39, 2025/02

https://doi.org/10.1080/14686996.2024.2428153