ON THE RELATIONSHIP BETWEEN AMBIENT DOSE EQUIVALENT AND ABSORBED DOSE IN AIR IN THE CASE OF LARGE-SCALE CONTAMINATION OF THE ENVIRONMENT BY RADIOACTIVE CESIUM
One of the main aims of the study was an experimental determination of the conversion coefficient from ambient dose equivalent rate, Н*(10), to absorbed dose rate in air, D, in the case of radioactive contamination of the environment following the Chernobyl accident. More than 800 measurements of ga...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Saint-Petersburg Research Institute of Radiation Hygiene after Professor P.V. Ramzaev
2015-10-01
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| Series: | Радиационная гигиена |
| Subjects: | |
| Online Access: | https://www.radhyg.ru/jour/article/view/242 |
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| Summary: | One of the main aims of the study was an experimental determination of the conversion coefficient from ambient dose equivalent rate, Н*(10), to absorbed dose rate in air, D, in the case of radioactive contamination of the environment following the Chernobyl accident. More than 800 measurements of gamma-dose rates in air were performed at the typical locations (one-storey residential house, street, yard, kitchen-garden, ploughed field, undisturbed grassland, forest) of rural settlements and their surroundings in the heavily contaminated areas of the Bryansk region, Russia in the period of 1996–2010. Five commercially available models of portable gamma-ray dosimeters were employed in the investigation. All tested dosimeters were included into the State register of approved measuring instruments of Russia. In all dosimeters, scintillation detectors are used as detection elements. A photon spectrometry technique is applied in the dosimeters to determine gamma dose rate in air. The dosimeters are calibrated in terms of exposure rate, X, absorbed dose rate in air, D, and ambient dose equivalent rate, Н*(10). A very good agreement was found between different dosimeters calibrated in the same units; the reading ratios were close to 1 and the correlation coefficients (Pearson’s or Spearman’s) were higher than 0.99. The Н*(10)/D ratio values were location-specific ranging from 1.23 Sv/Gy for undisturbed grasslands and forests to 1.47 Sv/Gy for wooden houses and asphalted streets. A statistically significant negative correlation (Spearman’s coefficient = -0.833; P<0.01; n=9) was found between the Н*(10)/D ratio and the average energy of gamma-rays determined with a NaI(Tl)-based gamma-ray monitor. For the whole area of a settlement and its surroundings, the average ratio of Н*(10) to D was calculated as 1.33 Sv/Gy. The overall conversion coefficient from ambient dose equivalent rate, Н*(10), to external effective dose rate, Ė, for adults was estimated by a value of 0.52 Sv/Sv. This value is valid for the remote period after the severe radiation accident that had resulted in large-scale contamination of the environment by radioactive cesium. The findings of this study are discussed in comparison with results obtained by other researches shortly after the Chernobyl and Fukushima accidents. |
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| ISSN: | 1998-426X |