Floating object removal in underwater ROV video images using segment anything model and generative image in-painting

Takahashi, Hiroki*; Kato, Toru*; Yamashita, Meguru*; Doi, Akio*; Imabuchi, Takashi

Artificial Life and Robotics, 31(2), p.598 - 610, 2026/05

https://doi.org/10.1007/s10015-025-01100-7

X-ray inverse fluorescence approach for accurate determination of Fe valence in Fe-rich geological materials

Nakada, Ryoichi*; Okuda, Hanaya*; Suga, Hiroki*; Yamaguchi, Akiko; Takahashi, Yoshio*; Kawazoe, Takaaki*

Geochemical Journal, 60(2), p.18 - 26, 2026/03

https://doi.org/10.2343/geochemj.GJ26003

Iron undergoes redox transitions between ferrous (Fe) and ferric (Fe) states, playing a key role in various geoscientific processes from Earth's interior to surface environments. Partial fluorescence yield X-ray absorption near edge structure analysis (PFY-XANES) is widely used to evaluate iron valence, but it is susceptible to thickness and self-absorption effects in high-concentration samples. In this study, we applied the inverse fluorescence yield method (IPFY) to geological samples and demonstrated that it enables more accurate iron valence determination than PFY. IPFY-XANES suppressed overestimation of the Fe ratio and reduced thickness effects. This method is expected to be a powerful non-destructive tool for analyzing natural samples such as meteorites and high-pressure recovered specimens.

Advancement of the personnel protection system for J-PARC front-end accelerator test stand

Chimura, Motoki; Watanabe, Kazuhiko*; Takahashi, Hiroki; Hirano, Koichiro; Shinto, Katsuhiro; Kitamura, Ryo; Kawase, Masato*; Suzuki, Takahiro*; Morishita, Takatoshi

Proceedings of 22nd Annual Meeting of Particle Accelerator Society of Japan (Internet), p.709 - 713, 2026/03

https://www.pasj.jp/web_publish/pasj2025/proceedings/PDF/FRP0/FRP006.pdf

no abstracts in English

Speciation of cesium in a radiocesium-bearing microparticle emitted from Unit 1 during the Fukushima nuclear accident by XANES spectroscopy using transition edge sensor

Takahashi, Yoshio*; Miura, Hikaru*; Yamada, Shinya*; Sekizawa, Oki*; Nitta, Kiyofumi*; Hashimoto, Tadashi*; Yomogida, Takumi; Yamaguchi, Akiko; Okada, Shinji*; Itai, Takaaki*; et al.

Journal of Hazardous Materials, 495, p.139031_1 - 139031_19, 2025/09

https://doi.org/10.1016/j.jhazmat.2025.139031

In this presentation, we analyzed the chemical state of cesium in radiocesium-bearing microparticles (CsMPs) released during the 2011 Fukushima Daiichi Nuclear Power Plant accident using high-resolution X-ray absorption spectroscopy (XANES) and micro X-ray fluorescence (-XRF). The results identified two forms of cesium: one dissolved in glass and the other enriched on the surfaces of internal voids. The latter is considered to have originally existed as a gas and became concentrated during the cooling and solidification of the molten glass. These findings are crucial for understanding the formation process of CsMPs during the accident, as well as for future decommissioning and safety assessments.

Development of time-series point cloud data changes and automatic structure recognition system using Unreal Engine

Kato, Toru*; Takahashi, Hiroki*; Yamashita, Meguru*; Doi, Akio*; Imabuchi, Takashi

Artificial Life and Robotics, 30(1), p.126 - 135, 2025/02

https://doi.org/10.1007/s10015-024-00983-2

R&D status of digital technology on inverse estimation of radioactive source distributions and related source countermeasures; Fast Digital Twin Tech. in Decommissioning Field: 3D-ADRES-Indoor FrontEnd

Machida, Masahiko; Yamada, Susumu; Kim, M.; Tanaka, Satoshi*; Tobita, Yasuhiro*; Iwata, Ayako*; Aoki, Yuto; Aoki, Kazuhisa; Yanagisawa, Kenichi*; Yamaguchi, Takashi; et al.

RIST News, (70), p.3 - 22, 2024/09

Inside the Fukushima Daiichi Nuclear Power Plant (1F), there are many locations with high radiation levels due to contamination by radioactive materials that leaked from the reactor. These pose a significant obstacle to the smooth progress of decommissioning work. To help solve this issue, the Japan Atomic Energy Agency (JAEA), under a subsidy from the Ministry of Economy, Trade, and Industry's decommissioning and contaminated water management project, is conducting research and development on digital technologies to improve the radiation environment inside the decommissioning site. This project, titled "Development of Technology to Improve the Environment Inside Reactor Buildings (Enhancing Digital Technology for Environment and Source Distribution to Reduce Radiation Exposure)," began in April of FY 2023. In this project, the aim is to develop three interconnected systems: FrontEnd, Pro, and BackEnd. The FrontEnd system, based on the previously developed 3D-ADRES-Indoor (prototype) from FY 2021-2022, will be upgraded to a high-speed digital twin technology usable on-site. The Pro system will carry out detailed analysis in rooms such as the new office building at 1F, while the BackEnd system will serve as a database to centrally manage the collected and analyzed data. This report focuses on the FrontEnd system, which will be used on-site. After point cloud measurement, the system will quickly create a 3D mesh model, estimate the radiation source from dose rate measurements, and refine the position and intensity of the estimated source using recalculation techniques (re-observation instructions and re-estimation). The results of verification tests conducted on Unit 5 are also presented. Furthermore, the report briefly discusses the future research and development plans for this project.

Development of new synchronized data system for J-PARC RCS

Takahashi, Hiroki; Saha, P. K.; Yoshimoto, Masahiro; Sawabe, Yuki*

Journal of Physics; Conference Series, 2687(7), p.072019_1 - 072019_5, 2024/01

https://doi.org/10.1088/1742-6596/2687/7/072019

In J-PARC 3 GeV Rapid Cycling Synchrotron, the synchronized data system using reflective memory has been constructed. In order to support the requirement of using larger size data in high intensity beam operation in the future, a new synchronized data generation method has been proposed. The new method implements in the measurement system the functions performed by the high-level computer in the current system, thereby realizing synchronized data generation using data transfer via LAN. In this study, we have constructed a test bench for the new synchronized data system that implements the proposed method and verified its performance. This result leads to the development of the new synchronized data system based on data transfer via LAN. In this paper, we describe the outline of the new synchronized data generation method and the results of performance tests.

Development of time-series point cloud data changes and automatic structure recognition system using Unreal Engine

Kato, Toru*; Takahashi, Hiroki*; Yamashita, Meguru*; Doi, Akio*; Imabuchi, Takashi

Proceedings of 29th International Symposium on Artificial Life and Robotics (AROB 29th 2024) (Internet), p.1097 - 1100, 2024/01

Upgrade of acquisition and monitoring system for J-PARC accelerator PPS

Watanabe, Kazuhiko*; Niki, Kazuaki*; Takahashi, Hiroki; Yamamoto, Noboru*; Yoshimoto, Masahiro; Fukuta, Shimpei*

Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.844 - 847, 2023/11

https://www.pasj.jp/web_publish/pasj2023/proceedings/PDF/FRP0/FRP09.pdf

J-PARC Personnel Protection System (PPS) acquires and displays data using by PPS Data System. PPS Data System has been using SCADA software, but it has become difficult to handle increased data due to the limited number of signals. Then, it became necessary to build PPS Data System using different software. Therefore, we decided to construct a new system using EPICS, which has been used in the J-PARC control system. On the other hand, PPS is a system that guarantees the safety of personnel, so it cannot be shut down for long periods of time. In addition, it is the most important safety system and must maintain high reliability and stability, so it would be dangerous to update the entire system in a short period of time. Therefore, we decided to divide the PPS Data System by function and replace it with the new system partially while operating the current system. This allows us to verify the operation of the updated parts and correct any problems without compromising the functionality of the PPS, and to construct a new system with high reliability and stability. This presentation will provide an overview of the new system, the updating process, and the progress.

Reducing the effect of noise generated from stepper motor for H0 collimator in J-PARC RCS

Fujiyama, Hiroki*; Takahashi, Hiroki; Okabe, Kota; Ito, Yuichi*; Hatakeyama, Shuichiro; Suzuki, Takahiro*; Otsu, Satoru*; Yamakawa, Ryuto*

Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.529 - 531, 2023/01

http://www.pasj.jp/web_publish/pasj2022/proceedings/PDF/WEP0/WEP010.pdf

Stepper motors are used for mechanical drive in collimators and wire scanner monitors of J-PARC accelerators. Many of these drive unit hardware have been used since the beginning of J-PARC construction, and it is necessary to take measures against aging deterioration. Therefore, we started updating the motor and control system from around 2017. However, when the stepper motor was updated to the current product in the RCS H0 collimator, a malfunction occurred. This is because the drive unit control system cannot correctly recognize the state of the LS (limit switch) due to the noise generated by the motor driver, which hinders the operation. When the noise generated from the old and new stepper motors was measured in a simple test environment for confirmation, it was found that the current product was clearly larger. As a countermeasure, when the wiring of the stepper motor, which was bundled in a single multi-core cable, was separated into separate cables for the power system and LS signal system, the noise level was reduced to about 1/10 and normal operation was restored. I was able to. In this case, we report on noise countermeasures for the RCS H0 collimator drive unit.