Removal and storage of asbestos-containing materials used in radiation controlled areas

Ishida, Reiya; Aoki, Emi; Sonobe, Hiroshi; Oto, Tsutomu; Kimura, Akihiro

JAEA-Review 2026-019, 50 Pages, 2026/07

JAEA-Review-2026-019.pdf:5.3MB

Subsequent to a leakage incident in October 2012 involving the SFC waste liquid transfer piping in the C Trench, additional leakage incidents occurred in the No. 4 drainage system piping and the SFC waste resin transfer piping. Furthermore, leakage incidents occurred in the tank yard, including seepage at welded joints in the waste liquid piping, as well as leakage from the waste liquid tanks. Since these incidents, the transfer of liquid waste from the hot laboratory facility to the JMTR tank yard has been suspended. Currently, as the waste liquid piping in the JMTR tank yard and the waste liquid tanks receiving liquid waste from the hot laboratory have been replaced and in sound condition, a plans is being developed to resume liquid waste transfer. To confirm the integrity of the waste liquid piping system, which runs from the hot laboratory through the C Trench to the tank yard, radiographic testing (hereafter referred to as "RT") of the pipe welds will be conducted. As it has been confirmed that the waste liquid piping is wrapped with asbestos-containing thermal insulation materials, these materials will be removed from the piping prior to RT. During this removal work, it is essential to comply with applicable laws and regulations and to ensure worker safety. This report summarizes the plan for removal of asbestos-containing thermal insulation materials in radiation controlled areas in order to minimize asbestos-related risks, as well as the procedures for the removal work and the methods for storage management.

Operation experiences of radioactivity monitoring system for the mercury system in J-PARC

Harada, Masahide; Tajima, Takahiro*; Ito, Taku*; Masuda, Shiho; Kinoshita, Hidetaka; Sakai, Kenji; Muto, Giichi*; Suzuki, Akio*; Haga, Katsuhiro

JPS Conference Proceedings (Internet), 45, p.011053_1 - 011053_5, 2026/06

https://doi.org/10.7566/JPSCP.45.011053

At Materials and Life science experimental Facility (MLF) in J-PARC, a mercury target of an intense pulsed spallation neutron source is designed to be irradiated by 3 GeV and 1MW proton beams to provide high intensity neutron beams to a suit of neutron instruments. A unified mercury radioactivity monitor (UHAM) is installed to find an indication of failure of the mercury target and loop system by detecting radioactive materials leaked from the system with a gamma-ray energy analysis with Germanium semi-conductor detectors. It is composed of three units of sampling port and radiation monitors: 1) HAM for interstitial helium gas layer between the mercury vessel and surrounding water shroud of the mercury target, 2) CAM for atmosphere in the hot cell where the target loop is operated and 3) VAM for helium gas in the helium vessel where the target vessel is installed. Once any leakages of radioactive materials are detected, an alarm signal is issued immediately to the accelerator control system to stop beam operation. Software and hardware have been upgraded yearly. For example, two Ge detectors are used for HAM for redundancy, NaI Scintillation detectors are also used as supplemental for the Ge detector to keep availability of the system for high counting rate event. In addition, A gas monitor is equipped at CAM to detect tritium. Until now, several operation experiences could be obtained as the follwoing. 1) Xe-121 and Xe-123 gas could be detected at CAM. These radio-active gaseous radioactive nuclides are slightly leaked from cover gas of mercury target. 2) Humidity in the helium vessel could be detected at VAM, because detection of annihilation gamma-ray and N-15 were increased. 3) The detection of Ar-41 indicated the air mixing in helium atmosphere.

Collapse of Jahn-Teller phonons in LaSrMnO with weak magnetoresistance

Sterling, T. C.*; Savici, A. T.*; Kajimoto, Ryoichi; Ikeuchi, Kazuhiko*; Khan, N.*; Weber, F.*; Reznik, D.*

Communications Materials (Internet), 7, p.121_1 - 121_11, 2026/05

https://doi.org/10.1038/s43246-026-01139-4

Cesium sorption onto alkaline activated materials

Hagiwara, Hiroki; Takaku, Atsushi*; Sagawa, Hiroshi*; Kanno, Futoshi*; Ito, Azusa; Ando, Taichi*; Ichihara, Masatsugu*; Watanabe, Yusuke; Koarai, Kazuma; Kato, Jun; et al.

Proceedings of Waste Management Symposia 2026 (WM2026) (Internet), 7 Pages, 2026/03

Development of nuclear security technologies for a large public event (Collaboration research)

Takahashi, Tone; Mochimaru, Takanori*; Koizumi, Mitsuo; Yoshimi, Yuki*; Yamanishi, Hirokuni*; Wakabayashi, Genichiro*; Ito, Fumiaki*

JAEA-Review 2025-039, 34 Pages, 2025/11

JAEA-Review-2025-039.pdf:2.18MB

To prevent acts of terrorism involving nuclear or radioactive materials at major public events, it is required to have surveillance technologies that either prevent these materials from being brought in or detect quickly if somebody brings them in secretly. Setting radiation gate monitors to survey pedestrians and vehicles is one of the effective methods. However, considering the possibility of individuals bypassing these monitors, complementary technologies are needed to continuously survey areas inside the gates. To survey extensive areas, radiation mapping is effective. By using multiple detectors and aggregating the data, the survey becomes much more efficient. We have developed mobile detectors capable of simultaneously measuring location data and radiation levels outdoors, with the ability to aggregate measurement results via a network and immediately visualize them on a map. For indoor environments, we have developed a technology that integrates radiation measurement results with environmental mapping created using SLAM (Simultaneous Localization and Mapping) to produce 3D maps of the surveyed areas. Additionally, we have been working on the development of a source search technology using a fast neutron detector to quickly detect neutron sources, including nuclear materials. In this report, we describe a concept of the wide area survey system and report technology development results so far.

Uncertainty reduction of the FPs transport mechanism and debris degradation behavior and evaluation of the reactor contamination of debris state on the basis of the accident progression scenario of Fukushima Daiichi Nuclear Power Station Unit 2 and 3 (Contract research); FY2023 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Institute of Science Tokyo*

JAEA-Review 2025-012, 96 Pages, 2025/10

JAEA-Review-2025-012.pdf:3.99MB

JAEA/CLADS had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). Among the adopted proposals in FY2021, this report summarizes the research results of the "Uncertainty reduction of the FPs transport mechanism and debris degradation behavior and evaluation of the reactor contamination of debris state on the basis of the accident progression scenario of Fukushima Daiichi Nuclear Power Station unit 2 and 3" conducted from FY2021 to FY2023. The present study aims to elucidate the cause of the high dosage under shield plug by clarification of to the cesium behavior of migration, adhesion to structure and deposition as well as evaluate the properties of metal-rich debris predeceasing melted through the materials science approach based on the most probable scenario of accident progression of Unit 2 and 3. Through three years investigation, chemi-absorption configuration of Cs has been elucidated to change with acidity of steel surface during oxidation in humid atmosphere and CsO trapping compound as well as penetration depth have found to be importantly considered. For metallic debris, solid oxidation was found to be controlled by FeO formation and molten state was found to tend to preferentially yield ZrO resulting in formation of slate structure during solidification. Present findings obtained are contributing to better improve the accuracy of accident progression scenario in FDNPP in viewpoint of backward analysis.

Nacre-like MXene/polyacrylic acid layer-by-layer multilayers as hydrogen gas barriers

Auh, Y. H.*; Neal, N. N.*; Arole, K.*; Regis, N. A.*; Nguyen, T.*; Ogawa, Shuichi*; Tsuda, Yasutaka; Yoshigoe, Akitaka; Radovic, M.*; Green, M. J.*; et al.

ACS Applied Materials & Interfaces, 17(21), p.31392 - 31402, 2025/05

https://doi.org/10.1021/acsami.5c03632

Incorporation of boron into metakaolin-based geopolymers for radionuclide immobilisation and neutron capture potential

Niu, X.*; Elakneswaran, Y.*; Li, A.*; Seralathan, S.*; Kikuchi, Ryosuke*; Hiraki, Yoshihisa; Sato, Junya; Osugi, Takeshi; Walkley, B.*

Cement and Concrete Research, 190, p.107814_1 - 107814_17, 2025/04

https://doi.org/10.1016/j.cemconres.2025.107814

Robustness of ferromagnetism in van der Waals magnet FeGeTe to hydrostatic pressure

Wang, Y.*; Zeng, X.-T.*; Li, B.*; Su, C.*; Hattori, Takanori; Sheng, X.-L.*; Jin, W.*

Chinese Physics B, 34(4), p.046203_1 - 046203_6, 2025/03

https://doi.org/10.1088/1674-1056/adb26f

Two-dimensional van der Waals ferromagnet FeGeTe (FGT) holds a great potential for applications in spintronic devices, due to its high Curie temperature, easy tunability, and excellent structural stability in air. In this study, we have performed high-pressure neutron powder diffraction (NPD) up to 5 GPa, to investigate the evolution of its structural and magnetic properties with hydrostatic pressure. The NPD data clearly reveal the robustness of the ferromagnetism in FGT, despite of an apparent suppression by hydrostatic pressure. As the pressure increases from 0 to 5 GPa, the Curie temperature is found to decrease monotonically from 225(5) K to 175(5) K, together with a dramatically suppressed ordered moment of Fe, which is well supported by the first-principles calculations. Although no pressure-driven structural phase transition is observed up to 5 GPa, quantitative analysis on the changes of bond lengths and bond angles indicate a significant modification of the exchange interactions, which accounts for the pressure-induced suppression of the ferromagnetism in FGT.

Scenario analysis of future nuclear energy use in Japan, 1; Methodology of nuclear fuel cycle simulator: NMB4.0

Abe, Takumi; Oizumi, Akito; Nishihara, Kenji; Nakase, Masahiko*; Asano, Hidekazu*; Takeshita, Kenji*

Progress in Nuclear Science and Technology (Internet), 7, p.299 - 304, 2025/03

https://doi.org/10.15669/pnst.7.299

Currently, much research continues on stable energy sources that do not emit CO in order to achieve a carbon-neutral and sustainable society. Nuclear energy is one of the such sources, and various new reactors and reprocessing technologies are being developed. In order to implement the nuclear fuel cycle with these technologies, a nuclear fuel cycle simulator is required to quantitatively evaluate various quantities, such as the distribution of nuclear fuel materials and the scale of waste loading. For this purpose, NMB4.0 was developed in collaboration with Tokyo Institute of Technology and Japan Atomic Energy Agency. This code calculates the material balance of 179 nuclides including actinides and fission products (FPs) from the front-end to the back-end and simulates the nuclear fuel cycle in an integrated manner. Unlike other nuclear fuel cycle simulators, the code is capable of performing precise back-end analyses such as the number of radioactive wastes and the scale of the geological repository considering heat generation of waste package under diverse nuclear energy scenario, and is an open source code that runs on Microsoft Excel. By these features, it is possible to quantitatively study nuclear energy utilization strategies with various stakeholders. The presentation will detail the numerical model used in NMB4.0.