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Kim, M.; Malins, A.*; Machida, Masahiko; Yoshimura, Kazuya; Saito, Kimiaki; Yoshida, Hiroko*
Nihon Genshiryoku Gakkai Wabun Rombunshi (Internet), 22(4), p.156 - 169, 2023/11
Dose reduction factor of a Japanese house is important information in the external exposure estimation of returning residents. In 2019, a total of 19 wooden houses were surveyed in Iitate Village and Namie Town using a gamma plotter that can continuously measure the air dose rate. In addition, the characteristics of the reduction factor were investigated from the measured air dose rate. In the vicinity of houses, uncontaminated areas exist underneath houses and, the ratio of paved surfaces such as asphalt roads is relatively high; furthermore, the pavement has a tendency for the radiation source to decay quickly. Therefore, the air dose rate near the house showed a relatively low value in common at all sites. Air dose rates above unpaved surfaces showed higher values and larger variations than those above paved surfaces within a radius of 50 m form the center of a house. The reduction factor was widely distributed even for one house, if the ratio of every air dose rate observed inside and outside the house is considered. It is suggested that a realistic reduction factor may not be obtained when the reduction factor is obtained based on the measured values at a small number of points that do not have the representativeness of the radiation field to be measured.
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.
Sato, Rina; Yoshimura, Kazuya; Sanada, Yukihisa; Sato, Tetsuro*
Journal of Radiation Protection and Research, 47(2), p.77 - 85, 2022/06
After the Fukushima Daiichi Nuclear Power Station (FDNPS) accident, a model was developed to estimate the external exposure doses for residents who were expected to return to their homes after evacuation orders were lifted. However, the model's accuracy and uncertainties in parameters used to estimate external doses have not been evaluated. This study validates the model's accuracy by comparing the estimated effective doses with the measured personal dose equivalents. The personal dose equivalents and life pattern data were collected for 36 adult participants who lived or worked near the FDNPS in 2019. The estimated effective doses correlated significantly with the personal dose equivalents, demonstrating the model's applicability for effective dose estimation. However, the lower value of the effective dose relative to personal dose equivalent indoors could be because the conversion factor from ambient dose equivalent to effective dose did not reflect the actual environment.
Hosoda, Masahiro*; Nugraha, E. D.*; Akata, Naofumi*; Yamada, Ryohei; Tamakuma, Yuki*; Sasaki, Michiya*; Kelleher, K.*; Yoshinaga, Shinji*; Suzuki, Takahito*; Rattanapongs, C. P.*; et al.
Science of the Total Environment, 750, p.142346_1 - 142346_11, 2021/01
Times Cited Count：23 Percentile：86.19(Environmental Sciences)The biological effects of low dose-rate radiation exposures on humans remains unknown. In fact, the Japanese nation still struggles with this issue after the Fukushima Dai-ichi Nuclear Power Plant accident. Recently, we have found a unique area in Indonesia where naturally high radiation levels are present, resulting in chronic low dose-rate radiation exposures. We aimed to estimate the comprehensive dose due to internal and external exposures at the particularly high natural radiation area, and to discuss the enhancement mechanism of radon. A car-borne survey was conducted to estimate the external doses from terrestrial radiation. Indoor radon measurements were made in 47 dwellings over three to five months, covering the two typical seasons, to estimate the internal doses. Atmospheric radon gases were simultaneously collected at several heights to evaluate the vertical distribution. The absorbed dose rates in air in the study area vary widely between 50 nGy h
and 1109 nGy h. Indoor radon concentrations ranged from 124 Bq m
to 1015 Bq m. That is, the indoor radon concentrations measured exceed the reference levels of 100 Bq m recommended by the World Health Organization. Furthermore, the outdoor radon concentrations measured were comparable to the high indoor radon concentrations. The annual effective dose due to external and internal exposures in the study area was estimated to be 27 mSv using the median values. It was found that many residents are receiving radiation exposure from natural radionuclides over the dose limit for occupational exposure to radiation workers. This enhanced outdoor radon concentration might be as a result of the stable atmospheric conditions generated at an exceptionally low altitude. Our findings suggest that this area provides a unique opportunity to conduct an epidemiological study related to health effects due to chronic low dose-rate radiation exposure.
Saito, Kimiaki; Takahara, Shogo; Uezu, Yasuhiro
Nihon Genshiryoku Gakkai-Shi ATOMO
, 60(2), p.111 - 115, 2018/02
no abstracts in English
Saito, Kimiaki; Kurihara, Osamu*; Matsuda, Norihiro; Takahara, Shogo; Sato, Tetsuro*
Radioisotopes, 65(2), p.93 - 112, 2016/02
Late information is introduced on dose evaluation due to external exposures which employ an important role in the exposures due to the Fukushima accident. First, merits and demerits of the currently used two methods, that is the estimation based air dose rates and the measurements using personal dosimeters, are discussed indicating some basic data after a fundamental concept of external dose evaluation is provided. Next, main activities are summarized on external dose measurements and evaluations after the accident. Finally, a new trial on dose evaluation in introduced.
-ray absorbed doses inside human body in criticality accident situations using phantom and tissue-equivalent dosimetersSono, Hiroki; Kojima, Takuji; Soramasu, Noboru*; Takahashi, Fumiaki
JAERI-Conf 2005-007, p.315 - 320, 2005/08
Personal dosimeters provide a fundamental evaluation of external exposures to human bodies in radiation accidents. The dose distribution inside the body, which is needed to estimate the exposures from a result of personal dosimetry, has been evaluated mostly by computational simulations, while experimental data to verify the simulations are not sufficiently supplied, in particular, in criticality accident situations. For the purpose of obtaining the experimental data on external exposures inside the body, a preliminary experiment on criticality accident dosimetry was carried out at the Transient Experiment Critical Facility (TRACY) using a human phantom and tissue-equivalent dosimeters. The neutron and -ray absorbed doses inside the phantom could be satisfactorily measured by the combined use of an alanine dosimeter and a thermoluminescent dosimeter made of enriched lithium tetra borate. The doses measured in and on the phantom were regarded as reasonable in dose level and distribution by comparison with the doses measured in the free air.
-ray dose components in criticality accident situationsSono, Hiroki; Yanagisawa, Hiroshi*; Ono, Akio*; Kojima, Takuji; Soramasu, Noboru*
Journal of Nuclear Science and Technology, 42(8), p.678 - 687, 2005/08
Times Cited Count：4 Percentile：30.51(Nuclear Science & Technology)Component analysis of -ray doses in criticality accident situations is indispensable for further understanding on emission behavior of -rays and accurate evaluation of external exposure to human bodies. Such dose components were evaluated, categorizing -rays into four components: prompt, delayed, pseudo components in the period of criticality, and a residual component in the period after the termination of criticality. This evaluation was performed by the combination of dosimetry experiments at the TRACY facility using a thermoluminescent dosimeter (TLD) made of lithium tetra borate and computational analyses using a Monte Carlo code. The evaluation confirmed that the dose proportions of the above components varied with the distance from the TRACY core tank. This variation was due to the difference in attenuation of the individual components with the distance from the core tank. The evaluated dose proportions quantitatively clarified the contribution of the pseudo and the residual components to be excluded for accurate evaluation of -ray exposure.
Endo, Akira; Yamaguchi, Yasuhiro; Eckerman, K. F.*
JAERI 1347, 114 Pages, 2005/02
no abstracts in English
Endo, Akira; Yamaguchi, Yasuhiro; Eckerman, K. F.*
Radiation Protection Dosimetry, 105(1-4), p.565 - 569, 2003/09
Times Cited Count：12 Percentile：62.23(Environmental Sciences)The present paper discusses a strategy for the development of a new radioactive decay database, which will succeed ICRP Publ.38 used for dosimetry calculations. The development of the database requires 1) Consistency checking of the ENSDF used for compilation of the decay data, 2) Improvement of the computer code EDISTR for processing the ENSDF, and 3) Comparison with other decay data prepared from the different computer codes and libraries for the verification of the compiled data. This paper identifies several technical issues that need to be addressed for the development of the new radioactive decay database.
Endo, Akira; Yamaguchi, Yasuhiro
JAERI-Data/Code 2001-004, 157 Pages, 2001/03
JAERI-Data-Code-2001-004.pdf:11.27MB
New nuclear decay data used for dose calculation have been compiled for 817 radionuclides that are listed in ICRP Publication 38 (Publ.38) and for 6 additional isomers. The decay data were prepared using decay data sets from the Evaluated Nuclear Structure Data File (ENSDF), the latest version in August 1997. Basic nuclear properties in the decay data sets that are important for calculating energies and intensities of emissions were updated by referring to NUBASE. In addition, possible revisions of partial and incomplete decay data sets were done for their format and syntax errors, level schemes, normalization records, and so on. After that, the decay data sets were processed by EDISTR in order to compute the energies and intensities of 
particles, 
particles, rays, internal conversion electrons, X rays, and Auger electrons. The compiled data were prepared in two different types of format: Publ.38 and NUCDECAY formats. The decay data will be widely used for dose calculations in radiation protection and will be beneficial to a future revision of ICRP Publ.38.
Endo, Akira; Yamaguchi, Yasuhiro
Proceedings of 10th International Congress of the International Radiation Protection Association (IRPA-10) (CD-ROM), 8 Pages, 2000/05
no abstracts in English
Department of Health Physics; Safety Division, Naka; Safety Division, Takasaki; Radiation Control Division, Oarai; Utilities and Safety Division, Kansai; Operation Safety Administration Division, Mutsu
JAERI-Review 2000-001, p.225 - 0, 2000/03
JAERI-Review-2000-001.pdf:9.42MB
no abstracts in English
Endo, Akira; *; Yamaguchi, Yasuhiro
JAERI-Data/Code 99-035, 355 Pages, 1999/07
JAERI-Data-Code-99-035.pdf:14.77MB
no abstracts in English
Department of Health Physics; Safety Division, Naka; Safety Division, Takasaki; ; ; Operation Safety Administration Division, Mutsu
JAERI-Review 98-015, 239 Pages, 1998/12
no abstracts in English
Department of Health Physics; Safety Division, Naka; Safety Division, Takasaki; ; ; Operation Safety Administration Division, Mutsu
JAERI-Review 97-016, 248 Pages, 1997/12
JAERI-Review-97-016.pdf:7.82MB
no abstracts in English
Homma, Toshimitsu; Togawa, Orihiko
JAERI-Data/Code 96-034, 47 Pages, 1996/11
JAERI-Data-Code-96-034.pdf:1.64MB
no abstracts in English
Department of Health Physics; Safety Division, Naka; Safety Division, Takasaki; ;
JAERI-Review 96-014, 236 Pages, 1996/10
JAERI-Review-96-014.pdf:7.25MB
no abstracts in English
Department of Health Physics; Safety Division, Naka; Safety Division, Takasaki; ; Operation Safety Administration Division, Mutsu;
JAERI-Review 95-020, 264 Pages, 1995/11
JAERI-Review-95-020.pdf:8.68MB
no abstracts in English
Department of Health Physics; Safety Division, Naka; Safety Division, Takasaki; ; Operation Safety Administration Division, Mutsu;
JAERI-Review 94-007, 262 Pages, 1994/11
JAERI-Review-94-007.pdf:7.85MB
no abstracts in English
