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Journal Articles

The Effect and effectiveness of decontaminating a pond in a residential area of Fukushima

Katengeza, E. W.*; Ochi, Kotaro; Sanada, Yukihisa; Iimoto, Takeshi*; Yoshinaga, Shinji*

Health Physics, 121(1), p.48 - 57, 2021/07

 Times Cited Count:0 Percentile:0.02(Environmental Sciences)

Special reconstruction and revitalization bases were designated in Fukushima's difficult-to-return zones by the Japanese government as targets of intensive decontamination to drastically lower air dose rates and enable residents to return. A pond amidst residences of one of these bases was targeted for decontamination and this study aimed at evaluating the effect and effectiveness of the decontamination by decontamination factor, air dose rate reduction factor, and the additional annual effective dose to residents. Air dose rates were measured in-situ with KURAMMA-II while soil core samples were collected and measured for radioactivity in the laboratory by gamma spectrometry. Lower decontamination factors were observed for more deeply distributed radiocesium soil profiles whereas areas covered with gravel demonstrated the largest reduction in air dose rates. Decontamination effectively lowered the radiocesium inventory and air dose rates by 51% and 37-91% respectively. Moreover, the additional annual effective dose to the public changed from 1.7$$pm$$0.79 mSv to 1.2$$pm$$0.57 mSv because of decontamination representing a dose aversion of 29%. These findings demonstrate how decontaminating ponds in residential areas can help to further lower the external exposure.

Journal Articles

Comprehensive exposure assessments from the viewpoint of health in a unique high natural background radiation area, Mamuju, Indonesia

Nugraha, E. D.*; Hosoda, Masahiro*; Kusdiana*; Untara*; Mellawati, J.*; Nurokhim*; Tamakuma, Yuki*; Ikram, A.*; Syaifudin, M.*; Yamada, Ryohei; et al.

Scientific Reports (Internet), 11(1), p.14578_1 - 14578_16, 2021/07

 Times Cited Count:1 Percentile:78.8(Multidisciplinary Sciences)

Mamuju is one of the regions in Indonesia which retains natural conditions but has relatively high exposure to natural radiation. The goals of the present study were to characterize exposure of the entire Mamuju region as a high natural background radiation area (HNBRA) and to assess the existing exposure as a means for radiation protection of the public and the environment. A cross-sectional study method was used with cluster sampling areas by measuring all parameters that contribute to external and internal radiation exposures. It was determined that Mamuju was a unique HNBRA with the annual effective dose between 17 and 115 mSv, with an average of 32 mSv. The lifetime cumulative dose calculation suggested that Mamuju residents could receive as much as 2.2 Sv on average which is much higher than the average dose of atomic bomb survivors for which risks of cancer and non-cancer diseases are demonstrated. The study results are new scientific data allowing better understanding of health effects related to chronic low-dose-rate radiation exposure and they can be used as the main input in a future epidemiology study.

Journal Articles

A Unique high natural background radiation area; Dose assessment and perspectives

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:5 Percentile:97.14(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$$^{-1}$$ and 1109 nGy h$$^{-1}$$. Indoor radon concentrations ranged from 124 Bq m$$^{-3}$$ to 1015 Bq m$$^{-3}$$. That is, the indoor radon concentrations measured exceed the reference levels of 100 Bq m$$^{-3}$$ 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.

Journal Articles

Epidemiological studies on indoor radon risk; A Review and current issues

Yonehara, Hidenori*; Ishimori, Yuu; Akiba, Suminori*; Iida, Takao*; Iimoto, Takeshi*; Kai, Michiaki*; Shimo, Michikuni*; Tokonami, Shinji*; Yamada, Yuji*; Yoshinaga, Shinji*; et al.

Hoken Butsuri, 42(3), p.201 - 213, 2007/09

The pooled analysis recently carried out in European countries and North American countries showed the excess relative risk of lung cancer increased by 10-20% per 100 Bqm$$^{-3}$$ increase in indoor radon concentration. The Scientific Committee on Indoor Radon Risk and Response to the Issue established by the Japan Health Physic Society reviewed the scientific evidence on the indoor radon risk obtained so far and evaluated the pooled analysis results from the viewpoint of estimating the risk coefficient in Japan. The committee concludes that the risk shown by the pooled analysis results has the consistency from miners risk analysis, and that it is probably not low in the reliability and validity, although the value may include the uncertainties caused from the correction of radon concentration measured, from the effect of thoron on measurement results, from the differences of environmental parameters in exposure, and so on.

Oral presentation

SVD in plasma shape reconstruction by CCS method

Nakamura, Kazuo*; Matsufuji, Shinji*; Tomoda, Seiji*; Wang, F.*; Mitarai, Osamu*; Kurihara, Kenichi; Kawamata, Yoichi; Sueoka, Michiharu; Sato, Konosuke*; Zushi, Hideki*; et al.

no journal, , 

no abstracts in English

Oral presentation

SVD in plasma shape reconstruction by CCS method

Nakamura, Kazuo*; Matsufuji, Shinji*; Tomoda, Seiji*; Wang, F.*; Mitarai, Osamu*; Kurihara, Kenichi; Kawamata, Yoichi; Sueoka, Michiharu; Sato, Konosuke*; Zushi, Hideki*; et al.

no journal, , 

no abstracts in English

Oral presentation

Feature of SVD in plasma shape reconstruction by CCS method

Nakamura, Kazuo*; Matsufuji, Shinji*; Tomoda, Seiji*; Wang, F.*; Mitarai, Osamu*; Kurihara, Kenichi; Kawamata, Yoichi; Sueoka, Michiharu; Sato, Konosuke*; Zushi, Hideki*; et al.

no journal, , 

no abstracts in English

Oral presentation

Current status and issues of low dose and low dose rate radiation risk estimation method; Current status and issues of dose assessment

Sakai, Kazuo*; Yamada, Yu*; Yoshida, Kazuo*; Yoshinaga, Shinji*; Sato, Kaoru; Ogata, Hiromitsu*; Iwasaki, Toshiharu*; Kudo, Shinichi*; Asada, Kyosei*; Kawaguchi, Isao*; et al.

no journal, , 

Task Group of Low dose and Low Dose Rate Radiation Risk Estimation Method in the Japan Health Physics Society presented the task group activity from April, 2016 to March, 2018. The presenter introduce the current status and issues of dose assessment (e.g. effects of anatomical characteristics of subjects, monitoring data, distribution of dose and dose rate in body on uncertainty of dose assessment).

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