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| Measurement and Analysis of Radio-Nuclides Contents in Soil of the Northeast China |
| PENG Bang-bao, YAN Qiang, LI Tao-sheng, AN Dong, ZHANG Cheng-gong, ZHANG Peng-fei |
| Fundamental science on nuclear safety and simulation technology laboratory, Harbin 150001 China |
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Abstract Objective Radio-nuclides contents in soil of the Northeast China were measured. Based on the Results, the relationship between the radio-nuclides contents of different soil samples and some impact factors, such as the local climate, the source rocks, vegetation distribution, the degree of radioactive contamination and so on, was investigated. And the estimated value of annual effective dose was obtained. Methods Using NaI(TI) detectors, the radio-nuclides contents of standard soil sample, provided by the National Institute of Metrology of R. P. China, was measured to determine the efficiency (defined at full-energy-peak) of gamma-rays with the biggest branching ratio which were emitted from the radio-nuclides of 232Th、226Ra、238U and 40K. By analyzing the energy spectrum obtained by NaI(TI) detectors, the contents of radio-nuclides in soil samples were calculated out. Results By measuring the radioactivity of radio-nuclides in 26 soil samples from different zones of Northeast China, the radio-nuclides contents were calculated. The Results indicated that the contents, namely 52.9 Bq/kg for 232Th, 44.8 Bq/kg for 226Ra, 50.3 Bq/kg for 238U, 820.3 Bq/kg for 40K, increased slightly compared with the data obtained in past years. Conclusion The Results showed that the contents of 232Th had a maximum in residual-parent-material soils and minimum in deposit-parent-material soils, the contents of 236Ra and 238U had a maximum in alluvial-parent-material soils and minimum in residual-parent-material soils and the contents of 40K had a maximum in deposit-parent-material soils and minimum in alluvial-parent-material soils. As for the terrain, the contents of 232Th and 40K in soil samples from the plain land was smaller than sample from the mountain land, while the contents of 226Ra and 238U were the contrary. Theoretical calculation using the contents of Radio-nuclides in soils from different zones of Northeast China was carried and the estimated value of annual effective dose was obtained. With a value of 0.54 mSv/a, the calculated annual effective dose was in the normal range.
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Received: 21 August 2013
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