著者
永岡 美佳 藤田 博喜 中野 政尚 渡辺 均 住谷 秀一
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.48, no.2, pp.104-113, 2013 (Released:2014-03-06)
被引用数
1 or 0

Monthly deposition samples were collected at the Nuclear Fuel Cycle Engineering Laboratories located about 115 km south of the Fukushima Daiichi Nuclear Power Plant (NPP), and the radioactive nuclides were analyzed. Although radionuclides such as 131I, 129mTe-129Te and 132Te-132I with 134Cs and 137Cs were observed by gamma spectrometry at the early time of the Fukushima Daiichi NPP accident, only 134Cs and 137Cs were detected as of September 2011. The annual depositions of 134Cs and 137Cs were about 19,000 and 17,000 Bq m-2, respectively in March 2011-February 2012 after the accident. Moreover, 90Sr was detected in some samples. Monthly 90Sr deposition in March 2011 was 5.1 Bq m-2 month-1 and then decreased after that. On the other hand, 239, 240Pu concentration was the same level with the concentration before the accident.
著者
藤原 慶子 高橋 知之 高橋 千太郎
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.51, no.1, pp.19-26, 2016 (Released:2016-07-06)

The accident at the Fukushima nuclear power plant in 2011 caused the release of large amounts of tellurium (Te) isotopes, with radio-cesium (Cs) and radio-iodine (I), into the environment. The total amounts of 127mTe and 129mTe released from the nuclear power plant were estimated as 1.1 × 1015 and 3.3 × 1015 Bq, respectively. At the location where the deposition of 129mTe was relatively large, the ratio of the radioactivity of 129mTe to that of 137Cs reportedly reached 1.49 on June 14, 2011. Since 127mTe has a relatively long half-life, it possibly contributed to the internal radiation dose at the early stage after the accident. In this paper, the ratio of the committed effective dose of 127mTe to that of 137Cs after the oral ingestion of rice was estimated by using various reported parameters. The relevant parameters are: 1) the deposition ratios of 127mTe, 129mTe, and 134Cs to 137Cs; 2) the deposition ratio of 127mTe to 129mTe; 3) the transfer factors of Te and Cs; and 4) the effective dose coefficients for 127mTe, 129mTe, 134Cs, and 137Cs. The ratios of the committed effective dose of 127mTe to that of 137Cs were calculated for adults after a single ingestion at the time of the rice harvest. The ratio was 0.45 where the 129mTe/137Cs in the soil was higher and 0.05 where the level of 129mTe/137Cs was average. The ratio of the committed effective dose from 129mTe and 127mTe to that from 137Cs for one year reached 0.55 and 9.03 at the location where the level of 129mTe/137Cs in the soil was higher. These data could indicate that radioactive Te should not be disregarded in reconstructing the internal radiation dose from food for one year after the accident.
著者
加藤 秀起 古賀 佑彦 向山 隆史 戸松 弘孝 鈴木 友輔 鈴木 昇一
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.44, no.4, pp.380-386, 2009 (Released:2011-01-12)

In one of the accidents that might happen in the nuclear power station, there is a contamination accident caused by radioactive corrosion products during a periodic inspection. It is necessary to presume the skin absorbed dose from the adhesion area and the contamination density to forecast the level of the skin hazard by the adhesion of the radioactive substance. However, the data to forecast the local skin dose when the radioactive substance adhered handily is not maintained. In this paper, the absorbed dose in the skin surface neighborhood contaminated by radioactive corrosion products was calculated, and the relation between the adhesion area and the contamination density and the local absorption dose was derived. And, the approximate equation that forecast the integrated dose was derived from these data. As for the absorbed dose rate in depth 70 μm from the skin surface that became the index of the skin hazard, the contribution rate by 59Fe was the highest within 30 days, and the contribution of 60Co rose most after the 30th after the radioactive substance had adhered when the contamination density the adhesion area was the same. The relation between the initial contamination density and days that required it was graphed to reaching to the threshold by the integrated dose when the threshold dose in which the necrosis of the skin was caused was assumed to be 20 Gy. The absorbed dose commitment can be presumed from measurements of the contamination density by using this graph or the approximate equation.
著者
長岡 和則 佐藤 昭二 山中 武 大西 由子
出版者
日本保健物理学会
雑誌
保健物理 : hoken buturi (ISSN:03676110)
巻号頁・発行日
vol.44, no.1, pp.66-71, 2009-03

In order to estimate the environmental radiation dose rate level, measurements of the terrestrial gamma ray dose rates and cosmic ray ionizing components were conducted in public places such as park, street and train in Tokyo area. Measurements for 10s with a NaI(Tl) scintillation spectrometer were repeatedly carried out with walking. Terrestrial gamma ray dose rate ranges from 10nSv/h in a train to 80nSv/h on the stone road. Although cosmic ray ionizing component was constantly 30nSv/h in the outdoor, reductions by shielding effect were observed at underground and in the concrete building. Influence of radiopharmaceutical was measured in the stations where so many people exist. This shows that the same effect may occur in the environmental radiation monitoring.
著者
草間 朋子 中川 健朗 吉澤 康雄
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.20, no.4, pp.399-406, 1985 (Released:2010-02-25)
被引用数
1 or 0

The concept of population dose is of importance and of interest at the point of radiation protection of puplic. We devided it into two categories, source-related population dose and individual-related population dose, and estimated each population dose of Japan. We surveyed all sources that caused exposure to Japanese population. A number of sources, both naturally-occuring and man-made, contributed to population exposure. According to source-related dose assessment, average annual effective dose equivalent was about 3.3mSv, and about half of which, i. e. 1.6mSv, was given from medical exposure. And from the results of individual-related dose assessment we proposed the allocation of the annual dose limit of public for each controllable source, that is, 2.5mSv/yr to nuclear faculties, 1.0mSv/yr to miscellaneous sources, 1.5mSv/yr to probablistic exposure.
著者
藤原 慶子 山崎 敬三 高橋 知之 高橋 千太郎 北川 晃三 神藤 克人
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.47, no.4, pp.282-285, 2012 (Released:2013-12-17)

After the Fukushima Daiichi Nuclear Power Plant Accident, many people are concerned about the contamination of radioactive substances in their ordinary surrounding environment. In this study, we determined the levels of radioactive contamination with 137Cs in towels, very common textile products in our life, after exposing those to the soil collected from a farm field near Fukushima city. Three kinds of towels made from the same cotton fiber with different thickness were exposed to the soil under dry or water-suspension conditions. The radioactivities of 137Cs retained/absorbed were 30-50% of the loaded radioactivity per gram weight of the towel. When their weight and absorbency are taken into consideration, the differences in thickness did not so much affect the above values. Under standard washing condition, which mimic those with household washing machine, almost all the radioactive cesium were removed from the towels contaminated under the dry conditions, whereas only 50-70% were removed when the towels were contaminated under the wet conditions. A commercial soil-release treatment (Preshade-SR) didn't reduce the contamination under both dry and wet conditions, although processing the towels with silver nano-particles did.
著者
渡部 輝久
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.41, no.4, pp.221-233, 2006 (Released:2010-08-05)

Environmental protection is one of the key issues in the prospective policy and strategy of radiation protection. In this context, numerous efforts have been made for developing the framework for the protection of non-human species from ionizing radiation, especially in European countries and Unite States. The present report summarizes knowledge so far attained on the assessment of doses and radiation impact on marine organisms. Special attention was directed to the methodology for calculating absorbed doses of marine organisms, based on which a case study was also carried out for estimating absorbed dose rate of several species of marine organisms inhabiting in the coastal sea off Rokkasho-Mura, Aomori Prefecture where a spent nuclear fuel reprocessing plant came into operation.
著者
渡邉 正己
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.47, no.2, pp.118-123, 2012 (Released:2012-12-07)

It has been believed that the first target of radiation carcinogenesis is DNA. However, this is not proved for radiation carcinogenesis yet. We discovered that frequency of aneuploid cell was closely related to that of radiation-induced cell transformation and natural cell transformation by high-density cultivation, but gene mutation was not. Cell with p53 gene becomes tetraploid, but does not get tumorigenicity. On the other hand, cells without p53 gene function become a triploid easily, and acquire tumorigenicity. Both radiation exposure and high-density cultivation elevated the level of intracellular oxidative radicals. These radicals induced centrosome destabilization and produced cells carrying extra centrosome, which promote merotelic attachment of chromosome by altering spindle geometry. Unresolved merotelic attachments can give rise to lagging chromosomes at anaphase. Aneuploidy was seen in high frequency in early process of cell transformation. These results strongly suggest that a main target of carcinogenesis by low dose radiation is not DNA, but is centrosome, which are the proteins to constitute chromosomal homeostasis maintenance mechanism. In addition, this route may be the same as that of natural carcinogenesis. These serial results support necessity of a review of a LNT hypothesis at a radioprotective point of view.
著者
日本保健物理学会医療放射線リスク専門研究会
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.46, no.1, pp.42-51, 2011 (Released:2012-01-25)
被引用数
1 or 0

Radiation use in medicine generally gives us the benefit that outweighs the risk. However, some patients are much concerned about the risk while some medical people are unaware of radiation risk. The aim of this report is to review the low dose risk not only in the reports of ICRP, UNSCEAR, BEIR and French academy but also in the scientific papers that have been paid attention to. On these bases, we discuss the low dose risk and how we face the risk in medicine in order to go for medical use of radiation to the right way. In particular, we hope this report will support medical people as well as radiation protection experts should understand the radiation risk in medicine on current scientific basis.
著者
竹安 正則 住谷 秀一 古田 定昭
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.48, no.3, pp.141-149, 2013 (Released:2013-12-10)

On the basis of the measurement results of airborne radionuclide concentrations in the Nuclear Fuel Cycle Engineering Laboratories, Japan Atomic Energy Agency, the committed effective dose to adults and the committed equivalent dose to thyroid of infants by inhalation were estimated for various indoor and outdoor exposure scenarios. It was demonstrated that the indoor to outdoor airborne radionuclide concentration ratio had a dominant effect on the dose estimate. The committed effective dose to adults was estimated to 0.098 mSv, and the committed equivalent dose to thyroid of infants was 1.8 mSv. These doses were about 1/6 and about 1/9, respectively, compared to the provisional ones with such assumptions as continuous outdoor stay.
著者
斎藤 公明
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.46, no.3, pp.210-214, 2011 (Released:2012-07-28)
被引用数
4 or 0
著者
藤高 和信
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.31, no.4, pp.463-471, 1996 (Released:2010-02-25)
被引用数
1 or 0

Exposure to cosmic rays in commercial airplanes was outlined. Although cosmic rays are a type of natural radiation, the magnitude of their dose is significant in airplanes. Therefore, there may be demands to regulate the dose of cosmic rays received by aircrews. In order to find reasonable countermeasures, the first prerequisite is to estimate the dose of cosmic rays precisely. In this paper, various problems in the measurement and calibration of cosmic rays as well as dose estimation and the method of control were outlined. Data of in situ measurements and those obtained by model calculations are presented, and factors which affect the level of the dose are discussed. In addition, potential dose ranges received during various flight routes are shown for various dose conversion parameter sets. Characteristics of domestic flights in Japan are also mentioned.
著者
谷村 嘉彦 富田 純平 吉富 寛 吉澤 道夫 箱崎 亮三 高橋 荘平
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.51, no.3, pp.141-146, 2016 (Released:2016-11-18)

Photon spectra were measured inside and outside a house in Minami-Soma city by using a NaI(Tl) scintillation spectrometer. The photons were categorized into three groups according to their energy. The groups were (1) scattered photons, which include low energy photons, (2) direct photons from 134Cs and 137Cs sources and (3) the other photons. Then the ratios of the ambient dose equivalents H*(10) of the scattered photons to those of the direct photons from the 134Cs and 137Cs sources have been evaluated from the measured photon spectra. The ratios are high inside the house compared with those out of the house. It was found that the scattered photons contribute to the H*(10) by more than 50% inside the house. The ambient dose equivalent average energies of the scattered photons are around 0.25 MeV both inside and outside the house. These data is worthwhile to design the optimum shielding for the protection against the public radiation exposure.
著者
工藤 伸一 石田 淳一 吉本 恵子 水野 正一 大島 澄男 古田 裕繁 笠置 文善
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.51, no.1, pp.12-18, 2016 (Released:2016-07-06)

Radiation Effects Association has carried out radiation epidemiological study for nuclear industry workers during 1990-2010. We assembled a cohort of 204,103 workers. The average cumulative dose was 13.8 mSv (median 1.0 mSv, interquartile range (IQR) 0.0-10.7 mSv) and the average follow-up period was 14.2 year. The present report has not concluded that low-dose radiation increases cancer mortality based on the follow-up data through 2010. One reason is that analyses among 75,442 respondents― the average cumulative dose was 25.8 mSv (median 6.3 mSv, IQR 0.2-28.0 mSv) and the average follow-up period was 8.3 year―to the lifestyle surveys revealed the decrease of the ERR after adjusting for smoking habits or educational year, suggesting that confounder has a large effect on the association between radiation exposure and mortalities in the cohort. Another reason is that in analyses on all cohort members, no significant ERR was observed in all death, and leukemia excluding chronic lymphoid leukemia. Significant ERR was seen in all cancers excluding leukemia, but this significance of the ERR might be affected by confounder such as smoking, because the significance of the ERR in all cancers excluding leukemia originates in the significance of the ERR in lung cancer.