Investigations on distribution of radioactive substances owing to the Fukushima Daiichi Nuclear Power Station Accident in the fiscal year 2022 (Contract research)

Group for Fukushima Mapping Project

JAEA-Technology 2023-024, 176 Pages, 2024/03

JAEA-Technology-2023-024.pdf:22.16MB

This report presents results of the investigations on the distribution-mapping project of radioactive substances owing to TEPCO Fukushima Daiichi Nuclear Power Station (FDNPS) conducted in FY2022. Car-borne surveys, a measurement using survey meters, a walk survey and an unmanned helicopter survey were carried out to obtain air dose rate data to create their distribution maps, and temporal changes of the air dose rates were analyzed. Surveys on depth profile of radiocesium and in-situ measurements as for radiocesium deposition were performed. Based on these measurement results, effective half-lives of the temporal changes in the air dose rates and the deposition were evaluated. Score maps to classify the importance of the measurement points were created, and the factors causing changes in the score when monitoring data from multiple years were used were discussed. The range of fluctuation of past tritium concentration data in seawater was determined, and the causes of the fluctuation were discussed. Monitoring data in coastal area performed in 2022 owing to the comprehensive radiation monitoring plan was summarized, and temporal changes in cesium-137 were analyzed. Using the Bayesian hierarchical modeling approach, we obtained maps that integrated air dose rate distribution data acquired through surveys such as car-borne and walk surveys with respect to the region within 80 km from the FDNPS and Fukushima Prefecture. The measurement results for FY2022 were published on the "Database for Radioactive Substance Monitoring Data", and measurement data were stored as CSV format. Radiation monitoring and analysis of environmental samples owing to the comprehensive radiation monitoring plan were carried out.

Investigations on distribution of radioactive substances owing to the Fukushima Daiichi Nuclear Power Station Accident in the fiscal year 2020 (Contract research)

Group for Fukushima Mapping Project

JAEA-Technology 2021-025, 159 Pages, 2022/01

JAEA-Technology-2021-025.pdf:46.66MB

This report presents results of the investigations on the distribution-mapping project of radioactive substances owing to TEPCO Fukushima Daiichi Nuclear Power Station (FDNPS) conducted in FY2020. Car-borne surveys, a flat ground measurement using survey meters, a walk survey and an unmanned helicopter survey were carried out to obtain air dose rate data. Air dose rate distribution maps were created and temporal changes of the air dose rates were analyzed. Regarding radiocesium deposition into the ground, surveys on depth profile of radiocesium and in-situ measurements were performed. Based on these measurement results, effective half-lives of the temporal changes in the air dose rates and the deposition were evaluated. In the examination of scoring for classifying the importance of measurement points, a score map was created for Fukushima Prefecture and the 80 km zone from the FDNPS, and the factors causing changes in the score when monitoring data from multiple years were used were discussed. Using the Bayesian hierarchical modeling approach, we obtained maps that integrated the air dose rate distribution data obtained from aircraft monitoring, car-borne surveys, and walk surveys with respect to the region within 80 km from the FDNPS and Fukushima Prefecture. The measurement results for FY2020 were published on the "Expansion Site of Distribution Map of Radiation Dose", and measurement data were stored as CSV format. Radiation monitoring and analysis of environmental samples owing to the comprehensive radiation monitoring plan were carried out.

Investigations on distribution of radioactive substances owing to the Fukushima Dai-ichi Nuclear Power Station Accident in the fiscal year 2019 (Contract research)

Group for Fukushima Mapping Project

JAEA-Technology 2020-014, 158 Pages, 2020/12

JAEA-Technology-2020-014.pdf:23.82MB

This report presents results of the investigations on the distribution-mapping project of radioactive substances owing to TEPCO Fukushima Daiichi Nuclear Power Station (FDNPS) conducted in FY2019. Car-borne surveys, a flat ground measurement using survey meters, a walk survey and an unmanned helicopter survey were carried out to obtain air dose rate data. Air dose rate distribution maps were created and temporal changes of the air dose rates were analyzed. Regarding radiocesium deposition into the ground, surveys on depth profile of radiocesium and in-situ measurements were performed. Based on these measurement results, effective half-lives of the temporal changes in the air dose rates and the deposition were evaluated. In the examination of scoring to classify the importance of measurement points, we created a score map of Fukushima Prefecture and that within 80 km from the FDNPS based on the "score" method developed in 2018. The way of monitoring radioactive materials in land area was examined and the representativeness of monitoring points was proposed. Using the Bayesian hierarchical modeling approach, we obtained maps that integrated the air dose rate distribution data obtained from aircraft monitoring, car-borne surveys, and walk surveys with respect to the region within 80 km from the FDNPS and Fukushima Prefecture. The measurement results for FY2019 were published on the "Expansion Site of Distribution Map of Radiation Dose", and measurement data were stored as CSV format. Radiation monitoring and analysis of environmental samples owing to the comprehensive radiation monitoring plan were carried out.

Investigations on distribution of radioactive substances owing to the FDNPP accident in the fiscal year 2018 (Contract research)

Group for Fukushima Mapping Project

JAEA-Technology 2019-019, 135 Pages, 2020/03

JAEA-Technology-2019-019.pdf:22.01MB

After the accident at TEPCO Fukushima Daiichi Nuclear Power Station (FDNPS), distribution situation survey on radioactive materials have been conducted with financially supported by the Ministry of Education, Culture, Sports, Science and Technology (later the Nuclear Regulatory Agency) from June 2011 to FY2018. Results obtained in the project in FY2018 are presented in this report. Car-borne surveys, a flat ground measurement using survey meters, a walk survey and an unmanned helicopter survey were carried out to obtain air dose rate data. Air dose rate distribution maps were created and temporal changes of air dose rate were analyzed. Regarding radiocesium deposition in the soil, depth profile survey in the soil and in-situ measurement were performed. Based on these measurement results, effective half-life of the air dose rate and the deposition were evaluated. Considering radiation monitoring data obtained in previous surveys and the installation positions of existing monitoring posts, we tried to make the "score" of the importance of measurement points. Using the Bayesian hierarchical modeling approach, we obtained a map that integrated the air dose rate distribution data obtained from aircraft monitoring, car-borne surveys, and walk surveys for the entire region within 80 km from the FDNPS. The measurement results for FY2018 were published on the "Expansion Site of Distribution Map of Radiation Dose", and measurement data were stored as CSV format. Radiation monitoring and environmental sample analysis owing to the comprehensive radiation monitoring plan were carried out.

Ion and neutron beam analyses of hydrogen isotopes

Kubota, Naoyoshi; Ochiai, Kentaro; Kutsukake, Chuzo; Kondo, Keitaro*; Shu, Wataru; Nishi, Masataka; Nishitani, Takeo

Fusion Engineering and Design, 81(1-7), p.227 - 231, 2006/02

https://doi.org/10.1016/j.fusengdes.2005.09.022

Hydrogen isotopes play important roles in the fuel recycling, the plasma condition etc. at the surface region of plasma facing components. The Fusion Neutronics Source (FNS) of Japan Atomic Energy Research Institute has started microanalysis studies for fusion components since 2002 by applying the beam analyses. In this study, we have measured tritium depth profiles of TFTR tiles exposed to the deuterium-tritium plasma to reveal the hydrogen isotope behavior at the surface region using some microscopic techniques for material analyses at FNS. As the result of the deuteron nuclear reaction analysis, four kinds of elements; deuterium, tritium, lithium-6 and lithium-7, were identified from the energy spectra. Using the spectra, depth profiles of each element were also calculated. The tritium profile had a peak at 0.5 micron, whereas the deuterium and lithium profiles were uniform from the surface to 1.0 micron depth. In addition, the surface region of the TFTR tile has retained the tritium more than one order of magnitude in the bulk.

3-45MeV/u ion beam dosimetry using thin film dosimeters

Kojima, Takuji; Sunaga, Hiromi; Takizawa, Haruki*; Hanaya, Hiroaki; Tachibana, Hiroyuki*

Radiation Physics and Chemistry, 68(6), p.975 - 980, 2003/12

https://doi.org/10.1016/j.radphyschem.2003.02.001

Four kinds of film dosimeters well-characterized for low LET radiations were applied to 3-45 MeV/u ions. The dose responses relative to those for low LET radiations are almost one up to about 10 MeV/(mg/cm) and gradually become smaller with increase of the stopping power. Overall uncertainty in ion beam dosimetry using these characterized dosimeters is better than 5%(1) including uncertainty in fluence measurement(2%). Lateral and depth dose profile measurements were achievable using characterized Gafchromic dosimeters with the spatial resolution of better than 1 and 10 m, respectively.

Measurements of the depth profile of the refractive indices in oxide films on SiC by spectroscopic ellipsometry

Iida, Takeshi*; Tomioka, Yuichi*; Yoshimoto, Kimihiro*; Midorikawa, Masahiko*; Tsukada, Hiroyuki*; Orihara, Misao*; Hijikata, Yasuto*; Yaguchi, Hiroyuki*; Yoshikawa, Masahito; Ito, Hisayoshi; et al.

Japanese Journal of Applied Physics, Part 1, 41(2A), p.800 - 804, 2002/02

https://doi.org/10.1143/JJAP.41.800

no abstracts in English

Radiation-induced trapped charge in metal-nitride-oxide-semiconductor structure

Takahashi, Yoshihiro*; Onishi, Kazunori*; Fujimaki, Takeshi*; Yoshikawa, Masahito

Proceedings of 3rd International Workshop on Radiation Effects on Semiconductor Devices for Space Application, p.10 - 15, 1998/00

no abstracts in English

Study on dosimetry systems for a few tens MeV/u ion beams

Kojima, Takuji; Sunaga, Hiromi; Takizawa, Haruki; Tachibana, Hiroyuki

JAERI-Conf 97-003, 00(00), p.492 - 494, 1997/00

https://jopss.jaea.go.jp/pdfdata/JAERI-Conf-97-003.pdf

no abstracts in English

Micro profile of the chemical structure in ion-beam irradiation effects for some polyolefins

Hama, Yoshimasa*; *; Hamanaka, Kenichi*; Matsumoto, Hideya*; Kudo, Hisaaki; Sasuga, Tsuneo; Seguchi, Tadao; *

Proceedings of of the Yayoi Symposium on Ion-Beam Radiation Chemistry; NIRS-M-101, HIMAC-007, 0, p.9 - 12, 1994/00

no abstracts in English