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Sato, Rina; Sanada, Yukihisa; Yoshimura, Kazuya; Nakayama, Mariko*
JAEA-Review 2022-055, 42 Pages, 2023/01
JAEA-Review-2022-055.pdf:1.31MB
The evacuation order zones established after the accident at the Tokyo Electric Power Company's Fukushima Daiichi Nuclear Power Station have been reorganized according to the decrease in ambient dose equivalent rates and the decontamination progress. It has been decided to decontaminate the difficult-to-return zones and lift the evacuation order depending on the evacuee's intention of returning to the areas over the course of the 2020s. In order to consider the future of individual exposure dose assessment for residents for lifting of the evacuation orders, the methods and characteristics of the assessment that have been conducted after the accident using personal dosimeter measurements and simulations were systematically reviewed. This report summarized the results of the review.
Ando, Masaki; Saito, Kimiaki
JAEA-Technology 2021-032, 66 Pages, 2022/03
JAEA-Technology-2021-032.pdf:3.84MB
Since the occurrence of the accident at the TEPCO Fukushima Daiichi Nuclear Power Station, the Japan Atomic Energy Agency (JAEA) has been conducting a series of car-borne survey over a wide area in the eastern part of Japan using the monitoring system KURAMAII. In this report, outline of the car-borne surveys are summarized and the following characteristics of the temporal changes in each prefecture and region were investigated using the measured data obtained from 2012 to 2019; 1) Average and maximum values for each prefecture for the six years from 2014 to 2019, 2) Average values for each prefecture from 2012 to 2019, 3) Average values for each evacuation order area category, regional category, and northern Soso-area municipality in Fukushima Prefecture from 2012 to 2019, and 4) Average and maximum values for each municipality in each prefecture for four times (at almost two-year intervals) of the measurement results from 2012 to 2018.
Ando, Masaki; Matsuda, Norihiro; Saito, Kimiaki
Nihon Genshiryoku Gakkai Wabun Rombunshi, 20(1), p.34 - 39, 2021/03
We measured count rates and air dose rates at 11 measurement points where the influence of the Fukushima Dai-ichi Nuclear Power Plant accident could be ignored to obtain parameters for a background equation applying to KURAMA-II loaded with the high sensitivity CsI(Tl) detector, C12137-01. It was found that the sensitivity of KURAMA-II (C12137-01) was about 10 times or more for background measurement, compared with KURAMA-II loaded with the standard type CsI(Tl) detector, C12137. A background equation for the energy range of 1400-2000 keV was determined as, y (
Sv/h)=0.062 x (cps). We evaluated background air dose rates using KURAMA-II (C12137-01) for 71 municipalities and compared them with the previous study using KURAMA-II (C12137). Evaluated background air dose rates in this study were almost equal to those in the previous study. We confirmed that the background equation evaluated in this study was applicable for the KURAMA-II (C12137-01).
Yoshimura, Kazuya; Saegusa, Jun; Sanada, Yukihisa
Scientific Reports (Internet), 10(1), p.3859_1 - 3859_9, 2020/03
Times Cited Count：16 Percentile：63.84(Multidisciplinary Sciences)Ando, Masaki; Mikami, Satoshi; Tsuda, Shuichi; Yoshida, Tadayoshi; Matsuda, Norihiro; Saito, Kimiaki
Journal of Environmental Radioactivity, 192, p.385 - 398, 2018/12
Times Cited Count：14 Percentile：45.18(Environmental Sciences)Car-borne surveys using KURAMA systems have been conducted over a wide area in eastern Japan since 2011. The measurement data collected until 2016 was analyzed, and decreasing trend of the dose rates in regions within 80 km of Fukushima Dai-ichi Nuclear Power Plant were examined. The averaged dose rates tended to decrease considerably with respect to the physical decay of radiocaesium, and the ecological half-lives of the fast and slow decay components were estimated. The decrease of the dose rate in the forest was slower than its decrease in other regions, and the decrease of the dose rate in urban area was the fastest. The decrease in the dose rates obtained via the car-borne survey was larger than that obtained on flat ground with few disturbances using survey meters approximately 1.5 y after the accident; hereafter, the decrease in the dose rates obtained via the car-borne survey was same as the latter measurement.
Ando, Masaki; Yamamoto, Hideaki*; Kanno, Takashi*; Saito, Kimiaki
Journal of Environmental Radioactivity, 190-191, p.111 - 121, 2018/10
Times Cited Count：18 Percentile：52.33(Environmental Sciences)Ambient dose equivalent rates in various environments related to human lives were measured by walk surveys using the KURAMA-II systems from 2013 to 2016 around the Fukushima Dai-ichi Nuclear Power Plant. The dose rate of the locations where the walk survey was performed decreased to about 38% of its initial value in the 42 months, which was beyond that attributable to the physical decay. The air dose rates decreased depending on the level of the evacuation areas, and the decrease was slightly larger in populated areas where humans are active. The comparison of walk survey data with car-borne survey data indicated that the air dose rate varies largely even within a 100 m square area. The dose rates measured by the walk surveys were estimated to be medial of those along roads and those of undisturbed flat ground. The air dose rates measured by the walk surveys decreased quickly compared with the air dose rate from the flat ground measurement.
Saito, Kimiaki; Yamamoto, Hideaki
Radioisotopes, 63(11), p.519 - 530, 2014/11
This article aims to provide the basic meanings and features of the doses frequently used in the measurements and evaluations of environmental radiation due to the Fukushima Dai-ichi Nuclear Power Plant accident. The following doses are explained and compared: absorbed dose as basic physical quantity; effective dose and equivalent dose for judgment in radiation protection; and ambient dose equivalent 
(10) and individual dose equivalent 
p(10) for radiation measurements.
Nakamura, Takemi*; Tonoike, Kotaro; Miyoshi, Yoshinori
Radiation Protection Dosimetry, 110(1-4), p.483 - 486, 2004/09
Times Cited Count：2 Percentile：17.16(Environmental Sciences)Dose measurement and evaluation technique in criticality accident conditions with a thermo luminescence dosimeter (TLD) was studied at the Transient Experiment Critical Facility (TRACY) of Japan Atomic Energy Research Institute (JAERI). The tissue absorbed dose can be derived from the ambient dose equivalent given by measurement with a TLD using the conversion factor given by computation. Using this technique, the neutron dose around the SILENE reactor of the Institute for Radioprotection and Nuclear Safety (IRSN) of France was measured in the Accident Dosimetry Intercomparison Exercise (June 10-21, 2002) organized by OECD/NEA and IRSN. In this exercise, the 
dose was also measured with a TLD. In this report, measurements and evaluation results at TRACY and SILENE are presented.
Ito, Masashi; Shiraishi, Akemi; Murakami, Hiroyuki
JAERI-Tech 2001-048, 20 Pages, 2001/07
JAERI-Tech-2001-048.pdf:1.27MB
In Japan Atomic Energy Research Institute, a new type radiophotoluminescent(RPL) glass dosimeter is recently adopted replaced film badge for external personal monitoring. Some fundamental characteristics of this dosimeter, such as dose dependence linearity, energy dependence, dose evaluation accuracy against mixed irradiation condition,fading, etc.,were examined at the Facility of Radiation Standard(FRS),JAERI. The results have proved that the RPL glass dosimeter has sufficient characteristics in practical use as a personal dosimeter for all of the items examined.
Honda, Fumiya*; Kinase, Sakae
no journal, ,
Sato, Rina; Yoshimura, Kazuya; Sanada, Yukihisa; Sato, Tetsuro*; Mori, Tsubasa*; Takagi, Marie*
no journal, ,
In order to accurately estimate air dose rates of indoors with a high percentage of stay, indoor dose reduction factor was evaluated based on indoor and outdoor air dose rate measurements, taking into account air dose rates due to natural radionuclides. The measurements were conducted on wooden and concrete buildings in 2021 in municipalities with specified reconstruction and revitalization base. Indoor air dose rates were estimated from outdoor air dose rates using representative values of the evaluated indoor dose reduction factors. As a result, indoor air dose rates were estimated more accurately when the effect of natural radionuclides was taken into account, because the error indicators were smaller than those in the case without the effect of natural radionuclides.
