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.

Automatic data acquisition for visualizing radioactive substances by combining a gamma-ray imager and an autonomous mobile robot

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

Journal of Instrumentation (Internet), 16(1), p.P01020_1 - P01020_18, 2021/01

https://doi.org/10.1088/1748-0221/16/01/P01020

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

Variable-box segmentation of a three-dimensional point cloud for automatic estimation of discontinuities in rock mass

Matsukawa, Shun*; Itakura, Kenichi*; Hayano, Akira; Suzuki, Yukinori*

Journal of MMIJ, 133(11), p.256 - 263, 2017/11

https://doi.org/10.2473/journalofmmij.133.256

LIDAR detects a rock mass surface configurations as a point cloud. DiAna (Discontinuity Analysis) is a Matlab tool which was developed for geo-structural analysis of rock mass discontinuities. DiAna segments a point cloud into bounding boxes to estimate the surface of a rock mass. However, an expert's skills necessary to determine the appropriate size of the bounding boxes for DiAna. We developed the VBS (Variable-Box Segmentation) algorithm to determine the appropriate box size depending on the location of the point cloud and to estimate the surface of a rock mass. The performance of the VBS algorithms was evaluated by comparison with the DiAna algorithm. The results of comparison showed that the VBS algorithm estimated planes more accurately for the reference planes than the DiAna algorithm. Therefore, the VBS algorithm determines appropriate box sizes automatically depending on the location of the point cloud and estimates the surface appropriately.

Characteristics of high repetition rate wavelength tunable solid state laser for real time laser monitoring system

Maruyama, Yoichiro; Kato, Masaaki

JAERI-Research 2002-040, 15 Pages, 2003/02

JAERI-Research-2002-040.pdf:1.05MB

As a tunable laser source for the study of real time LIDAR techique to detect some trace impurities in atmosphere, a dye laser has been employed. As a dye laser is difficult to handle, it is considered that the dye laser may not be used as a practical light source. A tunable solid stat laser composed of an optical parametricc oscillaotr (OPO) which has a wider wavelength range is one of the promising tunable light sources, however, there is no OPO with high repetition rate and large pulse energy. Therefore high repetition rate lasing characteristics of OPO are studied. In this experiment, -Barium Borate (BBO) crystal is utilized as a gain meduim of OPO and pumped by the second harmonic of Nd:YAG laser with the pulse repetition rate of 0.5 kHz. The threshold pumping peak power for BBO-OPO is around 16 MW/cm. Maximum OPO average output power of around 5.4 W is obtained with the power conversion efficiency of around 45%. The averege output power of OPO is increasing with the pumping power and undesirable thermal effects are not observed.

Overview of Thomson scattering system in tokamak

Yamauchi, Toshihiko

RTM-96-4, 0, p.19 - 25, 1996/00

no abstracts in English

Atmosphere measurement by compact Raman Lidar under nuclear environment

Chigira, Tomoyuki*; Shiina, Tatsuo*; Saito, Hayato*; Manago, Naohiro*; Kuze, Hiroaki*; Hanyu, Toshinori; Kanayama, Fumihiko; Fukushima, Mineo

no journal, , 

The compact Raman Lidar is developed for the atmosphere measurement under nuclear environment, in which radiation ionize the water vapor and generate the water-cluster. In this study, the Raman lidar throws the NUV-beam of 349 nm and detects the backscattering echoes of water-Raman (396 nm) and the water-vapor-Raman (400 nm). Am-241 of 9 MBq was used for the radiation source. The results showed that the water-Raman increased and the water-vapor-Raman decreased under the nuclear environment. Its ratio becomes 3 times. It is well coincide with the estimation. The radius of water cluster was estimated 200 nm by the experiment.

Compact Raman Lidar measurement of liquid and vapor phase water under the influence of ionizing radiation

Shiina, Tatsuo*; Saito, Hayato*; Manago, Naohiro*; Kuze, Hiroaki*; Hanyu, Toshinori; Kanayama, Fumihiko; Fukushima, Mineo

no journal, , 

no abstracts in English

Development and demonstration of integrated Radiation Imaging System (iRIS) for 3-D visualization of radioactive substances

Sato, Yuki

no journal, , 

no abstracts in English