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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:76.35(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

Simple pretreatment method for tritium measurement in environmental water samples using a liquid scintillation counter

Nakasone, Shunya*; Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; et al.

Plasma and Fusion Research (Internet), 16, p.2405035_1 - 2405035_5, 2021/02

Removal of impurities such as organic and other types of dissolved matters from environmental water samples is required for precise analysis of tritium with a liquid scintillation counting method. In general, a distillation method is a conventional one for tritium analysis in environmental water samples, but is a time-consuming process that takes 24 hours for removal of impurities. We have proposed a rapid pretreatment method for tritium analysis, that uses ion exchange resins. In this study, we performed batch experiments, to evaluate the effectiveness of the ion exchange resins on the tritium measurement. The results obtained demonstrated that removal of impurities in the sample water by ion exchange resins can be achieved during a short period of time (i.e., in 5 min).

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:96.3(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

Japanese population dose from natural radiation

Omori, Yasutaka*; Hosoda, Masahiro*; Takahashi, Fumiaki; Sanada, Tetsuya*; Hirao, Shigekazu*; Ono, Koji*; Furukawa, Masahide*

Journal of Radiological Protection, 40(3), p.R99 - R140, 2020/09

 Times Cited Count:6 Percentile:77(Environmental Sciences)

UNSCEAR and the Nuclear Safety Research Association report the annual effective doses from cosmic rays, terrestrial radiation, inhalation and ingestion from natural sources. In this study, radiation doses from natural radiation sources in Japan were reviewed with the latest knowledge and data. Total annual effective dose from cosmic-ray exposure can be evaluated as 0.29 mSv. The annual effective dose from external exposure to terrestrial radiation for Japanese population can be evaluated as 0.33 mSv using the data of nationwide survey by the National Institute of Radiological Sciences. The Japan Chemical Analysis Center (JCAC) performed the nationwide radon survey using a unified method for radon measurements in indoor, outdoor and workplace. The annual effective dose for radon inhalation was estimated using a current dose conversion factor, and the values were estimated to be 0.50 mSv. The annual effective dose from thoron was reported as 0.09 mSv by UNSCEAR and then the annual effective dose from inhalation can be described as 0.59 mSv. According to the report of large scale survey of foodstuff by JCAC, the effective dose from main radionuclides due to dietary intake can be evaluated to be 0.99 mSv. Finally, Japanese population dose from natural radiation can be assessed as 2.2 mSv which is near to the world average value of 2.4 mSv.

Journal Articles

Preliminary investigation of pretreatment methods for liquid scintillation measurements of environmental water samples using ion exchange resins

Nakasone, Shunya*; Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; et al.

Plasma and Fusion Research (Internet), 15, p.2405027_1 - 2405027_3, 2020/05

A quick preprocessing system for tritium analysis of environmental samples is important to judge environmental influence of tritium releases due to accident or tritium-handling facilities. Analysis of tritium in water samples with liquid scintillation counting method requires removal of impurities such as organic matter and ion species from water samples. Generally, a distillation method is adopted as a pretreatment of analysis for tritium; however, the distillation method is a time-consuming process. The aim of this study is to evaluate a rapid pretreatment method for tritium analysis with ion exchange resin. From batch and column experiments that used inland water and ion exchange resin, we confirmed removals of impurities of the water sample and that the removal of impurities was possible for a short time (by 5 minutes).

Journal Articles

A Portable radioactive plume monitor using a silicon photodiode

Tamakuma, Yuki*; Yamada, Ryohei; Iwaoka, Kazuki*; Hosoda, Masahiro*; Kuroki, Tomohiro*; Mizuno, Hiroyuki*; Yamada, Koji*; Furukawa, Masahide*; Tokonami, Shinji*

Perspectives in Science (Internet), 12, p.100414_1 - 100414_4, 2019/09

In this study, a portable radioactive plume monitor using a silicon photodiode was developed for the detection of a radioactive plume (e.g. $$^{131}$$I, $$^{134}$$Cs and $$^{137}$$Cs) in an emergency situation. It was found that the background count rate was proportional to ambient dose equivalent rate and the detection limit for the monitor at 20 $$mu$$Sv h$$^{-1}$$ as an ambient dose equivalent rate was evaluated to be 187 Bq m$$^{-3}$$ using the ISO11929 method. These results suggest that the detection limit for the system can be decreased effectively by lead shielding with optimized thickness.

Journal Articles

Development of field estimation technique and improvement of environmental tritium behavior model

Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; Atarashi-Andoh, Mariko; et al.

Plasma and Fusion Research (Internet), 14(Sp.2), p.3405099_1 - 3405099_4, 2019/06

The Large Helical Device of the National Institute for Fusion Science started D-D experiments in 2017. To ensure the safety of the facility, it is important to develop evaluation methods for environmental tritium transfer. Tritiated water (HTO) in atmosphere and soil is transferred to plants, and organically bound tritium (OBT) is formed by photosynthesis. Prediction of OBT formation is important, because OBT accumulates in plants and causes dose through ingestion. The objective of this study is to estimate environmental tritium transfer using a simple compartment model and practical parameters. We proposed a simple compartment model consisting of air-soil-plant components, and tried to validate the model by comparison with a sophisticated model, SOLVEG. In this study, we plan to add wet deposition to the model and obtain parameters from measurements of soil permeability and tritium concentrations in air, soil and plants. We also establish rapid pretreatment methods for OBT analysis.

Journal Articles

Origin and chemical speciation of anthropogenic Iodine-129

Shima, Shigeki*; Gasa, Shinichi*; Amano, Hikaru; Nagao, Seiya*; Yamamoto, Masayoshi*; Momoshima, Noriyuki*; Furukawa, Masahide*; Kimura, Hideki*; Kawamura, Hisao*

JAEA-Conf 2008-003, p.28 - 31, 2008/04

Concentrations of $$^{129}$$I in surface seawater around Japan were approximately 2$$times$$10$$^{7}$$atoms/L in literatures. However, the atomic ratio of iodine to cesium was ten times as high as that of the global fallout. The origin of $$^{129}$$I in the water columns seems to be difficult to be explained by only the global fallout. Discharge from European plants was one of the possible origins of iodine from the standpoint of air mass trajectory analysis. Concentration of $$^{129}$$I in rain water was 10 times higher than that in surface seawater. Anthropogenic inorganic iodine in surface seawater predominantly dissolves as an iodide ion (I$$^{-}$$).

Oral presentation

Committee on dose assessments of Japanese population

Takahashi, Fumiaki; Ishimori, Yuu; Inagaki, Masayo*; Omori, Yasutaka*; Sanada, Tetsuya*; Sugino, Masato*; Furukawa, Masahide*; Hosoda, Masahiro*; Manabe, Kentaro; Yajima, Kazuaki*; et al.

no journal, , 

The Japan Health Physics Society (JHPS) established a committee on dose assessments of Japanese population in August, 2015. The committee consists of 12 members (researchers and technicians) who are engaged in natural radiation measurements, radiation monitoring, radiation dose assessment and so on. Discussion have been made on dose assessments for daily life exposure in Japan. At the first meeting, stragedy of the committee was discussed and terrestrial radiation, cosmic radiation. Radon and radioactivity in food were defined as the radiological source to be investigated. It was also decided that the committee also would investigate influential factors (e.g., dose assessment model, daily life pattern) on radiation dose assessments. In addition, the committee has a plan to make discussions how JHPS should undertake this issue in future. At the 49th Annual meeting of JHPS, the committee members report their activities and make discussions on radiation dose assessment of Japanese population with the participants to the meeting.

Oral presentation

Activities of Committee on Dose Assessments of Japanese Population

Takahashi, Fumiaki; Ishimori, Yuu; Sanada, Tetsuya*; Furukawa, Masahide*; Yasuda, Hiroshi*

no journal, , 

The Japan Health Physics Society (JHPS) launched Committee on Dose Assessments of Japanese Population, because public has interests on exposure that has been reported accompanying with monitoring data following the accident of Fukushima Dai-ichi Nuclear Power Plant. The Committee has made discussion on exposure from natural radiation. Radiation data have been investigated terrestrial $$gamma$$-rays, cosmic rays, radon and radioactive material in food, because these sources contribute to population in Japan. The model for radiation dose estimation is also the examination object in the Committee. A topics session for the Commission is held at the Congress of JHPS to make discussion on the population dose in Japan.

Oral presentation

Improvement of environmental tritium behavior model; Calculation of OBT concentration in plants using the MOGRA code

Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; Atarashi-Andoh, Mariko; et al.

no journal, , 

To ensure safety of fusion facilities, it is important to develop evaluation methods for tritium transfer in the environment. For estimation of tritium transfer in the terrestrial environment, we had developed a simple compartment model using the Migration Of GRound Additions (MOGRA) code. The model was composed by an air-soil-plant system. The target source terms were HT and HTO in the air. In addition, wet deposition was modeled by input of HTO to the system by rainfall. Tritium in the plant was divided into free water tritium (FWT) and organically bound tritium (OBT). The tritium concentration in the environmental medium was trial calculated for chronic and accidental HTO releases to the atmosphere, as preliminary calculation run of the model.

Oral presentation

Development of a new sampler for tritium measurement in the infiltrated soil water

Kakiuchi, Hideki*; Tanaka, Masahiro*; Fukutani, Satoshi*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; Atarashi-Andoh, Mariko; Furukawa, Masahide*; et al.

no journal, , 

no abstracts in English

12 (Records 1-12 displayed on this page)
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