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Zhumadilov K.,Hiroshima University | Ivannikov A.,Medical Radiological Research Center | Zharlyganova D.,Astana Medical University | Stepanenko V.,Medical Radiological Research Center | And 8 more authors.
Radiation Measurements | Year: 2011

The method of electron spin resonance (ESR) dosimetry was applied to human tooth enamel to obtain estimates of individual absorbed dose for residents of Makanchi, Urdzhar and Taskesken settlements located near the Kazakhstan-Chinese border (about 400 km to the South-East, from the Semipalatinsk Nuclear Test Site (SNTS) and about 1000 km from the Lop Nor Nuclear Weapons Test Base, China). Since the ground and atmospheric nuclear tests (1964-1981) at Lop Nor, the people residing in these settlements are believed to have been heavily exposed to radioactive fallout. Tooth samples had been extracted for medical reasons during the course of ordinary dental treatment. The village of Kokpekty, located 400 km to the South-east of the SNTS, was chosen as the control group since it has not been subjected to any radioactive contamination. The mean excess doses in tooth enamel obtained after subtraction of the contribution of natural background radiation do not exceed 62 ± 28 mGy, 64 ± 30 mGy, 49 ± 27 mGy and -19 ± 36 mGy for all ages of the residents of Makanchi, Urdzhar, Taskesken and the control village of Kokpekty, respectively. © 2011 Elsevier Ltd. All rights reserved. Source


Yamamoto M.,Kanazawa University | Tomita J.,Kanazawa University | Sakaguchi A.,Hiroshima University | Ohtsuka Y.,Japan Institute for Environmental Sciences | And 2 more authors.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2010

Radiochemical results of U isotopes (234U, 235U and 238U) and their activity ratios are reported for well waters as local sources of drinking waters collected from the ten settlements around the Semipalatinsk Nuclear Test Site (SNTS), Kazakhstan. The results show that 238U varies widely from 3.6 to 356 mBq/L (0.3-28.7 μg/L), with a factor of about 100. The 238U concentrations in some water samples from Dolon, Tailan, Sarzhal and Karaul settlements are comparable to or higher than the World Health Organization's restrictive proposed guideline of 15 μg (U)/L. The 234U/238U activity ratios in the measured water samples are higher than 1, and vary between 1.1 and 7.9, being mostly from 1.5 to 3. The measured 235U/238U activity ratios are around 0.046, indicating that U in these well waters is of natural origin. It is probable that the elevated concentration of 238U found in some settlements around the SNTS is not due to the close-in fallout from nuclear explosions at the SNTS, but rather to the intensive weathering of rocks including U there. The calculated effective doses to adults resulting from consumption of the investigated waters are in the range 1.0-18.7 μSv/y. Those doses are lower than WHO and IAEA reference value (100 μSv/y) for drinking water. © 2010 The Author(s). Source


Yamamoto M.,Kanazawa University | Kawai K.,Kanazawa University | Sakaguchi A.,Hiroshima University | Hoshi M.,Hiroshima University | And 2 more authors.
Radiation and Environmental Biophysics | Year: 2010

After the disintegration of the USSR in end of 1991, it became possible for foreign scientists to visit Kazakhstan, in order to investigate the radiological consequences of nuclear explosions that had been conducted at the Semipalatinsk nuclear test site (SNTS). Since the first visit in 1994, our group has been continuing expeditions for soil sampling at various areas around SNTS. The current level of local fallout at SNTS was studied through γ-spectrometry for 137Cs as well as α-spectrometry for 239,240Pu. Average values of soil inventory from wide areas around SNTS were 3,500 and 3,700 Bq m -2 for 137Cs and 239,240Pu, respectively, as of January 1, 2000. The average level of 137Cs is comparable to that in Japan due to global fallout, while the level of 239,240Pu is several tens of times larger than that in Japan. Areas of strong contamination were found along the trajectories of radioactive fallout, information on which was declassified after the collapse of the USSR. Our recent efforts of soil sampling were concentrated on the area around the Dolon village heavily affected by the radioactive plume from the first USSR atomic bomb test in 1949 and located 110 km east from ground zero of the explosion. Using soil inventory data, retrospective dosimetry was attempted by reconstructing γ-ray exposure from fission product nuclides deposited on the ground. Adopting representative parameters for the initial 137Cs deposition (13 kBq m -2), the refractory/volatile deposition ratio (3.8) and the plume arrival time after explosion (2.5 h), an absorbed dose in air of 600 mGy was obtained for the 1-year cumulative dose in Dolon village, due to the first bomb test in 1949. Considering possible ranges of the parameters, 350 and 910 mGy were estimated for high and low cases of γ-ray dose in air, respectively. It was encouraging that the deduced value was consistent with other estimations using thermal luminescence and archived monitoring data. The present method can be applied to other settlements affected by local fallout from SNTS. © 2010 Springer-Verlag. Source

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