Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Urushidate, Tadayuki*; Yoda, Tomoyuki; Otani, Shuichi*; Yamaguchi, Toshio*; Kunii, Nobuaki*; Kuriki, Kazuki*; Fujiwara, Kenso; Niizato, Tadafumi; Kitamura, Akihiro; Iijima, Kazuki
JAEA-Review 2022-023, 8 Pages, 2022/09
JAEA-Review-2022-023.pdf:1.19MB
After the accident of the Fukushima Daiichi Nuclear Power Station, the Japan Atomic Energy Agency has newly set up a laboratory in Fukushima and started measuring radioactivity concentrations of environmental samples. In October 2015, Fukushima Radiation Measurement Group has been accredited the ISO/IEC 17025 standard by the Japan Accreditation Board (JAB) as a testing laboratory for radioactivity analysis (
Cs, 
Cs) based on Gamma-ray spectrometry with germanium semiconductor detectors. The laboratory has measured approximately 60,000 of various environmental samples at the end of March 2022. The laboratory quality control and measurement techniques have been accredited by regular surveillance of JAB. In September 2019, the laboratory renewed accreditation as a testing laboratory for radioactivity analysis.
-ray Spectrometry of Environmental Samples Collected in FukushimaSaegusa, Jun; Yoda, Tomoyuki; Maeda, Satoshi; Okazaki, Tsutomu; Otani, Shuichi; Yamaguchi, Toshio; Kurita, Yoshiyuki; Hasumi, Atsushi; Yonezawa, Chushiro*; Takeishi, Minoru
Proceedings of 14th International Congress of the International Radiation Protection Association (IRPA-14), Vol.3 (Internet), p.1078 - 1085, 2017/11
After the nuclear accident at the Fukushima Daiichi Nuclear Power Plant in March 2011, the Japan Atomic Energy Agency has newly set up a laboratory for radioactivity analysis in Fukushima. At the laboratory, radioactivity concentrations of environmental samples such as soil, water, dust filter, plant, etc., approximately 1,000 samples in a month, are measured with high-resolution -ray spectrometry systems. The systems employ n-type HPGe detectors from Ortec. Since September 2012, characterization and upgrade of the systems have been performed aimed at enhancing reliability of analysis and convenience of customers. Resolving both systematic and technical issues, the laboratory has been accredited the ISO/IEC 17025 standard as a testing laboratory for radioactivity analysis.
Saegusa, Jun; Yoda, Tomoyuki; Murakami, Mitsuhiro; Takeishi, Minoru
Kankyo Hoshano Josen Gakkai-Shi, 5(2), p.79 - 93, 2017/06
After the Fukushima Daiichi Nuclear Power Plant (NPP) accident in March 2011, environmental radiation monitoring works have been continuously conducted throughout the Fukushima prefecture of Japan. Five-year transitions of ambient dose rates at 15 locations 20-60 km away from the NPPs were precisely analyzed to investigate their chronological change. Measured dose rates were successfully fitted into a function consisting of a factor reflecting the physical decay of radiocesium and the other component such as the weathering effect. The ecological half-lives derived from the function ranged from 3 to 27 years (average 10 years). The radiation shielding effect by snow covering was also studied with the obtained functions. Due to the effect, dose rates were lowered by 15-50% by 20-cm-deep snow covering, and the ambient doses integrated over the five years were found to decrease by up to 7% compared to those without the snow covering that can be predicted from the fit function.
Maeda, Satoshi; Yoda, Tomoyuki; Okazaki, Tsutomu; Otani, Shuichi; Saegusa, Jun
no journal, ,
no abstracts in English
-spectrometry with Ge semiconductor detectors for the analysis of environmental soil samplesSaegusa, Jun; Maeda, Satoshi; Kurita, Yoshiyuki; Yoda, Tomoyuki; Takeishi, Minoru
no journal, ,
no abstracts in English
Uezu, Yasuhiro; Ejiri, Akira; Yoda, Tomoyuki
no journal, ,
The Great East Japan Earthquake occurred on 11th March 2011. The Tsunami attacked the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co. As a result, electric power was lost, furthermore electronic power generators were broken. After failing to restore power, there was an explosion and a large amount of radionuclides were released to the atmosphere. Japan Atomic Energy Agency (JAEA) monitored air dose rates, radionuclides in the air and environmental samples. At that time, there were many problems in the environmental radiation monitoring. The dose was beyond the range of the air dose monitor in monitoring car. The Ge detector's iron and lead shields were contaminated by the air. No standard source as "the phantom" could be obtained for children under 4. The JAEA solved these problems by developing new monitoring techniques. In this presentation, these improvements are shown and proposed as a new generation environmental radiation monitoring technique.
Saegusa, Jun; Nagayama, Takehiro; Maeda, Satoshi; Okazaki, Tsutomu; Yoda, Tomoyuki; Takeishi, Minoru
no journal, ,
In the process of -ray spectrometry analyses for radioactivity measurements, the coincidence summing effect needs to be considered. In this study, the concidence summing correction factors for 605 and 796 keV -rays from various standard volume sources were evaluated based on the peak-to-total (P/T) ratio method. The results were compared with the values directly obtained from the measurements of these sources containing certified amount of Cs nuclide.
Saegusa, Jun; Yoda, Tomoyuki; Murakami, Mitsuhiro; Takeishi, Minoru
no journal, ,
no abstracts in English
Kurita, Yoshiyuki; Okazaki, Tsutomu; Maeda, Satoshi; Yoda, Tomoyuki; Saegusa, Jun
no journal, ,
no abstracts in English
Kurita, Yoshiyuki; Okazaki, Tsutomu; Maeda, Satoshi; Yoda, Tomoyuki; Saegusa, Jun
no journal, ,
no abstracts in English
Takeyasu, Masanori; Takeishi, Minoru; Yoda, Tomoyuki; Saegusa, Jun; Koizumi, Jin*; Tanabe, Tsutomu
no journal, ,
The measurement of air dose rate surrounding roads is important for developing plans for reducing radiation exposure with road traffic. The measurements were performed by vehicle-borne or man-borne surveys until now. However, air dose rate resulting from radioactivity on roads in mainly measured for former survey, and much man-power for long time measurement was necessary for the latter. In this study, we focused on the field of view for measurement being different with a difference of the detector setting height above the ground, and carried out the vehicle-borne survey along roads in evacuation zone in Fukushima prefecture with two detectors mounted at different heights. By this measurement, air dose rate surrounding the roads is discriminated. From the results, the radioactivity contamination trend was clarified, and are valuable for developing decontamination plan around the road.
Yoshida, Keisuke; Yamada, Katsunori; Yoda, Tomoyuki; Tsunoda, Junichi; Muto, Yasushi; Kobayashi, Makoto; Kikuchi, Masamitsu
no journal, ,
no abstracts in English
Nagayama, Takehiro; Maeda, Satoshi; Okazaki, Tsutomu; Yoda, Tomoyuki; Saegusa, Jun
no journal, ,
no abstracts in English
Saegusa, Jun; Maeda, Satoshi; Okazaki, Tsutomu; Yoda, Tomoyuki; Takeishi, Minoru
no journal, ,
no abstracts in English
Yoda, Tomoyuki; Maeda, Satoshi; Funaki, Hironori; Saegusa, Jun; Takeishi, Minoru
no journal, ,
In the measurement of the sample with different filling conditions, it is necessary to revise a detection efficiency. It systematize a correction factors of Ge detector efficiencies by Monte Carlo calculation and the measurement.
Maeda, Satoshi; Yoda, Tomoyuki; Okazaki, Tsutomu; Saegusa, Jun
no journal, ,
no abstracts in English
Saegusa, Jun; Yanagisawa, Kayo; Yamaguchi, Toshio; Manabe, Sachi; Yoda, Tomoyuki; Maeda, Satoshi; Utsumi, Azusa; Shibamichi, Masaru; Ejiri, Akira; Kurita, Yoshiyuki; et al.
no journal, ,
no abstracts in English
