Development of a laser deflection-type ultrasonic wideband 3D imaging system for in-vessel visualization in high-radiation and non-visible environments (Contract research); FY2024 Nuclear Energy Science & Technology and Human Resource Development Project

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

JAEA-Review 2026-007, 65 Pages, 2026/06

JAEA-Review-2026-007.pdf:4.67MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), has been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") from FY2019. 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). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2024, this report summarizes the research results of the "Development of a laser deflection-type ultrasonic wideband 3D imaging system for in-vessel visualization in high-radiation and non-visible environments" conducted in FY2024. The present study aims to maximize the safety of debris-cutting operations by enabling visualization of in-vessel structures, fuel debris shapes, and scattered particles at distances on the order of several meters, even under dusty and turbid water conditions during work. To achieve this, a compact and portable ultrasonic device suitable for mounting on robots and manipulator arms is employed to develop a laser deflection-type ultrasonic wideband 3D imaging system. In FY2024, the project carried out imaging performance evaluation and studies for the advancement and acceleration of the ultrasonic imaging system, numerical simulations, prototyping and full-scale verification of the system, radiation resistance tests, construction of a submillimeter ultrasonic ranging system, application of the ultrasonic sub-millimeter ranging system to LIBS, as well as battery-powered remote operation of the measurement system. These outcomes are summarized in this report.

Development of portable VR system for radiation work environment using 3-D environmental map visualizing radiation information as input data

Sato, Yuki; Minemoto, Kojiro*; Nemoto, Makoto*; Matsuura, Yasutaka*; Hayashi, Keisuke*

Proceedings of International Conference on Nuclear Decommissioning; Addressing the Past and Ensuring the Future 2023 (Internet), 4 Pages, 2025/00

The development of technology to visualize the distribution of radioactive substances at the decommissioning site of the Fukushima Daiichi Nuclear Power Station (FDNPS) is important for reducing worker exposure and developing a detailed work plan. Sato, one of the authors, developed an integrated Radiation Imaging System (iRIS) that combines a Simultaneous Localization and Mapping (SLAM) device, a Compton camera (a type of gamma-ray imager), and a survey meter, and have successfully produced a 3-D map of the working environment inside the FDNPS that visualizes the location of radioactive hot spots and the distribution of air dose rates. In addition, the authors are developing a system that enables users to experience the radiation environment of the FDNPS in virtual reality (VR) using the 3-D map visualizing such radiation information as input data. This VR system can use a commercially available portable VR head-mounted display, which not only displays the location of the radiation source in a virtual space, but also has the ability to calculate the exposure dose according to the working time. The development status of this VR system, which is expected to be effective in educating inexperienced workers and planning work, will be presented at the conference.

Development of a radioactive substance detection system integrating a Compton camera and a LiDAR camera with a hexapod robot

Sato, Yuki; Kakuto, Takeshi*; Tanaka, Takayuki*; Shimano, Hiroyuki*; Morohashi, Yuko; Hatakeyama, Tomoyoshi*; Nakajima, Junsaku; Ishiyama, Masahiro

Nuclear Instruments and Methods in Physics Research A, 1063, p.169300_1 - 169300_7, 2024/06

https://doi.org/10.1016/j.nima.2024.169300

Quantitative visualization of a radioactive plume with harmonizing gamma-ray imaging spectrometry and real-time atmospheric dispersion simulation based on 3D wind observation

Nagai, Haruyasu; Furuta, Yoshihiro*; Nakayama, Hiromasa; Satoh, Daiki

Journal of Nuclear Science and Technology, 60(11), p.1345 - 1360, 2023/11

https://doi.org/10.1080/00223131.2023.2197445

A novel monitoring method for the quantitative visualization of 3D distribution of a radioactive plume and source term estimation of released radionuclides is proposed and its feasibility is demonstrated by preliminary test. The proposed method is the combination of gamma-ray imaging spectroscopy with the Electron Tracking Compton Camera (ETCC) and real-time high-resolution atmospheric dispersion simulation based on 3D wind observation with Doppler lidar. The 3D distribution of a specific radionuclide in a target radioactive plume is inversely reconstructed from line gamma-ray images from each radionuclide by several ETCCs located around the target by harmonizing with the air concentration distribution pattern of the plume predicted by real-time atmospheric dispersion simulation. A prototype of the analysis method was developed, showing a sufficient performance in several test cases using hypothetical data generated by numerical simulations of atmospheric dispersion and radiation transport.

Radiation imaging using an integrated radiation imaging system based on a compact Compton camera under Unit 1/2 exhaust stack of Fukushima Daiichi Nuclear Power Station

Sato, Yuki; Terasaka, Yuta

Journal of Nuclear Science and Technology, 59(6), p.677 - 687, 2022/06

https://doi.org/10.1080/00223131.2021.2001391

3D position and radioactivity estimation of radiation source by a simple directional radiation detector combined with structure from motion

Sato, Yuki; Minemoto, Kojiro*; Nemoto, Makoto*

Radiation Measurements, 142, p.106557_1 - 106557_6, 2021/03

https://doi.org/10.1016/j.radmeas.2021.106557

Remote detection of radioactive hotspot using a Compton camera mounted on a moving multi-copter drone above a contaminated area in Fukushima

Sato, Yuki; Ozawa, Shingo*; Terasaka, Yuta; Minemoto, Kojiro*; Tamura, Satoshi*; Shingu, Kazutoshi*; Nemoto, Makoto*; Torii, Tatsuo

Journal of Nuclear Science and Technology, 57(6), p.734 - 744, 2020/06

https://doi.org/10.1080/00223131.2020.1720845

Radiation imaging using a compact Compton camera mounted on a crawler robot inside reactor buildings of Fukushima Daiichi Nuclear Power Station

Sato, Yuki; Terasaka, Yuta; Utsugi, Wataru*; Kikuchi, Hiroyuki*; Kiyooka, Hideo*; Torii, Tatsuo

Journal of Nuclear Science and Technology, 56(9-10), p.801 - 808, 2019/09

https://doi.org/10.1080/00223131.2019.1581111

Feasibility study on application of synchrotron radiation CT imaging to alloy steel for non-destructive inspection of inclusions

Shimamura, Yoshinobu*; Matsushita, Shinya*; Fujii, Tomoyuki*; Togo, Keiichiro*; Akita, Koichi*; Shobu, Takahisa; Shiro, Ayumi*

Metals, 9(5), p.527_1 - 527_9, 2019/05

https://doi.org/10.3390/met9050527

Radiation imaging using a compact Compton camera inside the Fukushima Daiichi Nuclear Power Station building

Sato, Yuki; Tanifuji, Yuta; Terasaka, Yuta; Usami, Hiroshi; Kaburagi, Masaaki; Kawabata, Kuniaki; Utsugi, Wataru*; Kikuchi, Hiroyuki*; Takahira, Shiro*; Torii, Tatsuo

Journal of Nuclear Science and Technology, 55(9), p.965 - 970, 2018/09

https://doi.org/10.1080/00223131.2018.1473171