Estimation of Inhaled Effective Doses of Uranium and Thorium for Workers in Bayan Obo Ore and the Surrounding Public, Inner Mongolia, China.

Uranium and thorium are two common natural radioactive elements with high concentrations in Earth's crust. The main aim of this study is to estimate the inhaled effective dose of uranium and thorium caused by a typical radioactive rare earth ore to the occupational population and the surrounding public. The particulate matter (PM) concentrations in the atmosphere of four typical workplaces and one surrounding living area were obtained by a high-flow sampling equipment with a natural cellulose filter membrane. The critical parameter for the inhaled effective dose estimation-the activity median aerodynamic diameter (AMAD)-was determined. The AMAD values of uranium and thorium in the atmosphere PM were 3.36 and 3.64 µm, respectively. The estimated median effective dose caused by inhalation thorium among the occupational population ranged from 15.3 to 269.0 µSv/a, and the corresponding value for the surrounding public was 2.3 µSv/a. All values for the effective dose caused by the inhalation of uranium were in the nSv magnitude.

Monitoring of ultra-trace uranium and thorium in six-grade particles.

The natural radioactive elements uranium(U) and thorium(Th) in atmospheric environment should be given attention, and their particle size distribution and concentration are important for estimating their hazardous effects to the human body. The concentrations of U and Th in 360 aerosol samples collected using six-stage aerosol collector from June - December, 2016 in Beijing were determinated using ICP-MS after acid digestion. The mass concentration ranges of U in PM0.39-0.69, PM0.69-1.3, PM1.3-2.1, PM2.1-4.2, PM4.2-10.2, and PM10.2- reached 0.0030-0.079, 0.0020-0.069, 0.0015-0.095, 0.0053-0.054, 0.0039-0.098, and 0.0083-0.10 ng/m3, respectively. The mass concentration range of Th in PM0.39-0.69, PM0.69-1.3, PM1.3-2.1, PM2.1-4.2, PM4.2-10.2, and PM10.2- amounted to 0.011-0.11, 0.0065-0.11, 0.0026-0.18, 0.0078-0.14, 0.015-0.30, and 0.0021-0.19 ng/m3, respectively. The contents of U and Th in all PM increased from June to December, and the contents in PM2.1 increased more sharply compared with those in other PM. A positive correlation was observed between the concentrations of U and Th and air quality index and relative humidity, whereas a negative correlation was identified between temperature and PM2.1, PM10.2, and total suspended particulates (TSP) after the Spearman-rank correlation test. The formation of PM was affected by meteorological conditions, which concurrently influenced the contents of U and Th in PM. The atmospheric contents of U and Th at night were higher than those in daytime. Compared with Th, the dose contribution of U to the public can be negligible. The median effective dose in public owing to inhalation of natural radioactive U and Th in the atmosphere measures 1.206 µSv/a.

Rapid method for determination of 90Sr in biological samples by liquid scintillation counting after separation on synthesized column.

A simple, rapid and cost-efficient method for determination of activity concentration of 90Sr in biological samples with an extraction chromatographic column (crown ether on teflon powder) and following counted by liquid scintillation counting was developed in this paper. The column retained most of 90Sr while almost all of matrix ions were removed during rinsing steps with 8M nitric acid and finally 90Sr was eluted with deionized water, the chemical recovery of strontium is greater than 60%, almost all of matrix ions were removed by the procedure we reported. Finally the uncertainty was evaluated and minimum detectable activity of this method is 1.28Bq/kg.

Radioactivity of drinking-water in the vicinity of nuclear power plants in China based on a large-scale monitoring study.

The public concern for radioactivity of drinking-water has been increasing in recent years after the rapid development of nuclear power plants, and especially after the Fukushima nuclear accident. In this study, the radioactivity of water samples collected in the vicinity of nuclear facilities from seven provinces in China was measured and an average annual equivalent effective dose derived from drinking-water ingestion was calculated. The results showed that, in winter and spring, the activities of gross α and ß ranged from 0.009 Bq/L to 0.200 Bq/L and from 0.067 Bq/L to 0.320 Bq/L, respectively. While, in summer and autumn, the activities of gross a and ß varied from 0.002 Bq/L to 0.175 Bq/L and from 0.060 Bq/L to 0.334 Bq/L. Our results indicated that the gross a and ß activities in these measured water samples were below the WHO recommended values (0.5 Bq/L for gross α and 1.0 Bq/L for gross ß) and the annual equivalent effective dose derived from drinking-water ingestion was at a safe level.