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Start Over Author "Ishikawa T" Journal radiation protection dosimetry
144 results on '"Ishikawa T"'

1. NATURAL RADIOACTIVITY LEVEL AND ELEMENTAL COMPOSITION OF SOIL SAMPLES FROM A HIGH BACKGROUND RADIATION AREAON EASTERN COAST OF INDIA (ODISHA)

Author

Sahoo, S.K., Kierepko, R., Sorimachi, A., Omori, Y., ishikawa, T., Tokonami, S., Prasad, G., S., Gusain G., and Ramola, R.C.

Abstract

A comprehensive study was carried out to determine the radioactivity concentration of soil samples from different sites of a high background radiation area in the eastern coast of India, Odisha state. The dose rate measured in situ varied from 0.25 to 1.2 mSv h-1. The gamma spectrometry measurements indicated Th series elements as the main contributors to the enhanced level of radiation and allowed the authors to find the mean level of the activity concentration (+SD) for 226Ra, 228Th and 40K as 130+97, 1110+890 and 360+140 Bq kg21, respectively. Human exposure from radionuclides occurring outdoor was estimated based on the effective dose rate, which ranged from 0.14+0.02 to 2.15+0.26 mSv and was higher than the UNSCEAR annual worldwide average value 0.07 mSv. Additionally, X-ray fluorescence analysis provided information about the content of major elements in samples and indicated the significant amount of Ti (7.4+4.9 %) in soils.

Published
2016

2. VARIABILITY OF RADIOCAESIUM INVENTORY IN FUKUSHIMA SOIL CORES FROM ONE SITE MEASURED AT DIFFERENT TIMES

Author

Mishra, S., S.K.Sahoo, Arae, H., Sorimachi, A., Hosoda, M., Tokonami, S., and ishikawa, T.

Abstract

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident has resulted in the deposition of radioactive contamination of soils mainly by 134Cs and 137Cs. The contaminated areas are of a great concern since external radiation may lead to significant long-term doses to humans and animals. External dose rate above ground will decrease with physical decay of the radionuclides and as they migrate deeper into the soil with time. In the present study, depth profiles of Cs radioisotopes have been studied at dif- ferent times over a period of 1 y. Radiocaesium inventories for 134Cs and 137Cs down to a depth of 10 cm at the four measurement times varied from 2.09 to 4.14 MBq m22 with coefficient of variation (CV): 27.4 %, n 5 4 and from 2.13 to 4.23 MBq m22 with CV: 27.3 %, n 5 4, respectively. The activity ratio for 134Cs/137Cs decreased from 0.62 to 0.46 during 1 y of measurement i.e. July 2012 to June 2013. However, the ratio with decay correction (15 March 2011) was found to be constant ∼1, indicating con- tamination from FDNPP origin. In order to understand the radiocaesium distribution in soil profile, physico-chemical character- isation of soil has been carried out.

Published
2015

3. COMPARATIVE DOSIMETRY FOR RADON AND THORON IN HIGH BACKGROUND RADIATION AREAS IN CHINA

Author

H.Kudo, Tokonami, S., Omori, Y., Ishikawa, T., Iwaoka, K., Sahoo, S.K., Akata, N., and M.Hosoda

Subjects
respiratory tract diseases
Abstract

The present study focuses on internal exposure caused by the inhalation of radon and thoron progenies because the internal exposures have not yet been clarified. For their dose assessment, radon, thoron and thoron progeny concentrations were measured by passive monitors over a long period (for 6 months). Consequently, radon, thoron and equilibrium equivalent thoron concen- trations were given as 124 + 78, 1247 + 1189 and 7.8 + 9.1 Bq m23, respectively. Annual effective doses are estimated to be 3.1 + 2.0 mSv for radon and 2.2 + 2.5 mSv for thoron. Total dose are estimated to be 5.3 + 3.5 mSv a21. The present study has revealed that the radon dose was comparable with the thoron dose, and the total dose was ∼2 times higher than the worldwide average.

Published
2015

7. EXTERNAL AND INTERNAL EXPOSURE TO FUKUSHIMA RESIDENTS

Author

Kamiya, K., primary, Ishikawa, T., additional, Yasumura, S., additional, Sakai, A., additional, Ohira, T., additional, Takahashi, H., additional, Ohtsuru, A., additional, Suzuki, S., additional, Hosoya, M., additional, Maeda, M., additional, Yabe, H., additional, Fujimori, K., additional, Yamashita, S., additional, Ohto, H., additional, and Abe, Masafumi, additional

Published
2016
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12. Preface

Author

Tokonami, S., primary, Mc Laughlin, J. P., additional, Chen, J., additional, Kovacs, T., additional, and Ishikawa, T., additional

Published
2015
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14. An evaluation of thoron (and radon) equilibrium factor close to walls based on long-term measurements in dwellings

Author

Mishra, R., primary, Zunic, Z. S., additional, Venoso, G., additional, Bochicchio, F., additional, Stojanovska, Z., additional, Carpentieri, C., additional, Prajith, R., additional, Sapra, B. K., additional, Mayya, Y. S., additional, Ishikawa, T., additional, Omori, Y., additional, Veselinovic, N., additional, Tollefsen, T., additional, Uji , P., additional, and Bossew, P., additional

Published
2014
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15. VARIABILITYOF RADIOCAESIUM INVENTORY IN FUKUSHIMA SOIL CORES FROM ONE SITE MEASUREDAT DIFFERENT TIMES.

Author

Mishra, S., Sahoo, S. K., Arae, H., Sorimachi, A., Hosoda, M., Tokonami, S., and Ishikawa, T.

Subjects
CESIUM isotopes, FUKUSHIMA Nuclear Accident, Fukushima, Japan, 2011, RADIOACTIVE substances in soils, RADIATION doses, RADIOACTIVE decay
Abstract

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident has resulted in the deposition of radioactive contamination of soils mainly by 134Cs and 137Cs. The contaminated areas are of a great concern since external radiation may lead to significant long-term doses to humans and animals. External dose rate above ground will decrease with physical decay of the radionuclides and as they migrate deeper into the soil with time. In the present study, depth profiles of Cs radioisotopes have been studied at different times over a period of 1 y. Radiocaesium inventories for 134Cs and 137Cs down to a depth of 10 cm at the four measurement times varied from 2.09 to 4.14 MBq m-2 with coefficient of variation (CV): 27.4 %, n = 4 and from 2.13 to 4.23 MBq m-2 with CV: 27.3 %, n = 4, respectively. The activity ratio for 134Cs/137Cs decreased from 0.62 to 0.46 during 1 y of measurement i.e. July 2012 to June 2013. However, the ratio with decay correction (15 March 2011) was found to be constant ~1, indicating contamination from FDNPP origin. In order to understand the radiocaesium distribution in soil profile, physico-chemical characterisation of soil has been carried out. [ABSTRACT FROM AUTHOR]

Published
2015
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16. NATURAL RADIOACTIVITYAND RADON EXHALATION RATES IN MAN-MADE TILES USEDAS BUILDING MATERIALS IN JAPAN.

Author

Iwaoka, K., Hosoda, M., Suwankot, N., Omori, Y., Ishikawa, T., Yonehara, H., and Tokonami, S.

Subjects
ATMOSPHERIC radon, NATURAL radioactivity, CONSTRUCTION materials, BACKGROUND radiation, RADON, CHEMICAL ecology
Abstract

Man-made tiles frequently used in Japan were collected, and activity concentrations and radon (222Rn) exhalation rates in these tiles were measured. Dose estimations for inhabitants living in houses built using these tiles were also carried out. The activity concentrations of 226Ra, 228Ra and 40K in the man-made tiles were 31-170, 35-110 and 260-980 Bq kg-1, respectively. The 222Rn exhalation rates in the tiles were 8.8-21 µBq m-2 s-1. The ranges of experimental activity concentrations and 222Rn exhalation rates were almost identical to those of natural rocks used as typical building materials in Japan. The maximum value of effective dose to inhabitants living in houses built with the man-made tiles was 0.14 mSv y-1, which is lower than the reference level range (1-20 mSv y-1) for abnormally high levels of natural background radiation published in the ICRP Publication 103. [ABSTRACT FROM AUTHOR]

Published
2015
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31. Effect of radon measurement methods on dose estimation

Author

Kavasi, N., primary, Kobayashi, Y., additional, Kovacs, T., additional, Somlai, J., additional, Jobbagy, V., additional, Nagy, K., additional, Deak, E., additional, Berhes, I., additional, Bender, T., additional, Ishikawa, T., additional, Tokonami, S., additional, Vaupotic, J., additional, Yoshinaga, S., additional, and Yonehara, H., additional

Published
2011
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32. Collaborative investigations on thoron and radon in some rural communities of Balkans

Author

Zunic, Z. S., primary, Celikovic, I., additional, Tokonami, S., additional, Ishikawa, T., additional, Ujic, P., additional, Onischenko, A., additional, Zhukovsky, M., additional, Milic, G., additional, Jakupi, B., additional, Cuknic, O., additional, Veselinovic, N., additional, Fujimoto, K., additional, Sahoo, S. K., additional, and Yarmoshenko, I., additional

Published
2010
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50. Determination of the minimum measurement time for estimating long-term mean radon concentration.

Author

Janik, M., Łoskiewicz, J., Tokonami, S., Kozak, K., Mazur, J., and Ishikawa, T.

Subjects
RADON, RADIATION measurements, SURVEYS, NUCLEAR track detectors, ERROR analysis in mathematics, ESTIMATION theory
Abstract

Radon measurements, as do any measurements, include errors in their readings. The relative values of such errors depend principally on the measurement methods used, the radon concentration to be measured and the duration of the measurements. Typical exposure times for radon surveys using passive detectors [nuclear track detectors, activated charcoal, electrostatic (E-perm), etc.)] may extend from a few days to months, whereas, in the case of screening methods utilising active radon monitors (AlphaGUARD, RAD7, EQF, etc.), the measurements may be completed quickly within a few hours to a few days. Thus, the latter may have relatively large error values, which affect the measurement accuracy significantly compared with the former measurements made over long time periods. The method presented in this paper examines the uncertainty of a short-term radon measurement as an estimate of the long-term mean and suggests a minimum measurement time to achieve a given margin of uncertainty of that estimate. [ABSTRACT FROM AUTHOR]

Published
2012
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