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.

Investigating eutectic behavior and material relocation in BC-stainless steel composites using the improved MPS method

Ahmed, Z.*; Wu, S.*; Sharma, A.*; Kumar, R.*; Yamano, Hidemasa; Pellegrini, M.*; Yokoyama, Ryo*; Okamoto, Koji*

International Journal of Heat and Mass Transfer, 250, p.127343_1 - 127343_17, 2025/11

https://doi.org/10.1016/j.ijheatmasstransfer.2025.127343

Heat transfer coefficient modeling for downward saturated boiling flows in vertical pipes

Wada, Yuki; Shibamoto, Yasuteru; Hibiki, Takashi*

International Journal of Heat and Mass Transfer, 249, p.127219_1 - 127219_16, 2025/10

https://doi.org/10.1016/j.ijheatmasstransfer.2025.127219

A Simplified quantification method for seismic risk assessment of nuclear fuel cycle facilities using Clark approximation

Kubo, Kotaro; Mori, Kenji*; Muramatsu, Ken

Nuclear Engineering and Design, 442, p.114176_1 - 114176_14, 2025/10

https://doi.org/10.1016/j.nucengdes.2025.114176

Experimental study on light gas transport during containment venting by using the large-scale test facility CIGMA

Soma, Shu; Ishigaki, Masahiro*; Shibamoto, Yasuteru

Annals of Nuclear Energy, 219, p.111455_1 - 111455_12, 2025/09

https://doi.org/10.1016/j.anucene.2025.111455

Sharp surface tension model with pressure discontinuity and refined curvature for multiphase particle methods

Wang, Z.; Matsumoto, Toshinori; Shibamoto, Yasuteru; Duan, G.*

Journal of Computational Physics, 537, p.114072_1 - 114072_29, 2025/09

https://doi.org/10.1016/j.jcp.2025.114072

Microstructural evolution and mechanical instability of Mar-M509 superalloy fabricated by laser powder bed fusion under short-term thermal exposure

Cao, T.*; Wei, D.*; Gong, W.; Kawasaki, Takuro; Harjo, S.; 10 of others*

Materials Science and Engineering A, 940, p.148534_1 - 148534_16, 2025/09

https://doi.org/10.1016/j.msea.2025.148534

Detection of beta-emitting radioactive hotspots inside the Fukushima Daiichi Nuclear Power Station Unit 3 reactor building using an optical fiber radiation sensor based on wavelength-resolving analysis

Terasaka, Yuta; Sato, Yuki; Ichiba, Yuta*

Radiation Measurements, 187, p.107486_1 - 107486_8, 2025/09

https://doi.org/10.1016/j.radmeas.2025.107486

Modeling the extraction of bound rubber from silica-filled styrene-butadiene rubber with toluene

Tamura, Yukiko*; Arakawa, Masato*; Takenaka, Mikihito*; Nakanishi, Yohei*; Fujinami, So*; Shibata, Motoki*; Yamamoto, Katsuhiro*; Miyata, Noboru*; Yamada, Masako*; Seto, Hideki*; et al.

Polymer, 333, p.128662_1 - 128662_8, 2025/08

https://doi.org/10.1016/j.polymer.2025.128662

Annual report for FY2023 on the activities of Department of Decommissioning and Waste Management (April 1, 2023 - March 31, 2024)

Department of Decommissioning and Waste Management

JAEA-Review 2025-006, 126 Pages, 2025/07

JAEA-Review-2025-006.pdf:4.45MB

This report describes the activities of Department of Decommissioning and Waste Management (DDWM) in Nuclear Science Research Institute (NSRI) in the period from April 1, 2023 to March 31, 2024. The report covers organization and missions of DDWM, outline and operation/maintenance of facilities which belong to DDWM, treatment and management of radioactive wastes, decommissioning activities, and related research and development activities which were conducted in DDWM. In FY2023 radioactive wastes generated from R&D activities in NSRI were treated safely. They were about 156 m of combustible solid wastes and 84 m of noncombustible solid wastes and 295 m of liquid wastes. After adequate treatment, 837 waste packages (in 200 L drum equivalent) were generated. The total amounts of accumulated waste packages were 118,664 as of the end of FY2023 due to efforts of the restitution of waste packages to the Japan Radioisotope Association and volume reduction treatments of the stored waste packages. Decommissioning activities were carried out for the JAEA's Reprocessing Test Facility. As for the R&D activities, studies on radiochemical analyses of wastes for disposal were continued. In order to pass the conformity review on the New Regulatory Requirements for waste management facilities, the Approval of the design and construction method was applied sequentially for the Nuclear Regulation Authority. The ministry of the Environment and Tokai-mura office requested JAEA to dispose of the contaminated soil generated by the accident of the Fukushima Daiichi Nuclear Power Station. The monitoring work at the playground was conducted during this period.