[en] The authors determined the contents of natural uranium and thorium in coal and tunnel ash samples taken from a large coal-fired power station in the nearby area. The hourly climate data in 1980 are analysed and the atmospheric stability is cataloged by Pasquill-Turner method. Wind direction-atmospheric stability-wind velocity combined probabilities and rain-wind direction probabilities are calculated. The near ground air pollution concentrations, the ground depositions and the distributions of U and Th presented in airborne effluent (fly ash) within an area round the station with a radius of 60 km are also estimated. In the calculations, some factors such as wind velocity in the higher atmosphere, plume rise, still wind and decrease of air pollution concentration by the ground deposition (especially the wet deposition porduced by rain) have been considered. Some corrections necessary for the factors described above are also made. It is shown that the maximum annual average air pollution concentration (U_max = 1.95 x 10^-7 mg.m^-3, Th_max = 3.45 x 10^-7 mg.m^-3) appears at the point 1 km away from the source in the fan SE. In the area round the station with a radius shorter than 10 km, the ground deposition is mainly by the wet deposition, but, where the radius longer than 10 km, the dry deposition must be taken into account

[en] The contents of natural uranium and thorium in coal and tunnel ash samples from a large coal-fired power plant were determined. The hourly climate data in 1980 were analysed and the wind direction, atmosphoric stability, wind speed joint frequencies f_ijk and rainfall-wind direction frequencies f_Rijk were calculated by using pasquill-turner method. The concentrations of U_nat and Th_nat in air near the ground surface and the ground deposition caused by airborne effluent (fly ash) from the plant and their distributions in the area around the plant within a radius of 60 km were estimated. In the calculation, some factors such as wind speed in the higher atmosphere, plume rise, still wind and the decrease of concentrations of pollutants in air by deposition (especially the wet deposition by rainfall) were cinsidered. The calculating results showed that the maximum annual average air pollution concentration appeared at the point of 1 km southeast of the source, where U = 1.95 x 10^-7 mg·m^-3, Th = 3.45 x 10^-7 mg·m^-3, respectively. In the area around the plant within a radius shorter than 10 km the wet deposition was dominant, the dry deposition must be taken into account at a distance beyond 10 km

[en] The authors described formulas for radon and its short-lived decay products in air by three-count technique according to boundary conditions for solving Bateman Equation from radioactive decay law. The computer programs have been written. Fromula errors in reference are pointed out. Some coefficients of published formulas are complemented and corrected. In addition, combined monitoring for radon and its daughters is realized after drawing into EECRn formula. Procedure optimization for radon daughters has been conducted successfully by means of the computer on the basis of mentioned above. The authors advanced an optimized procedure, i.e. the sampling of 5 min and the counting of 1 to 4, 6 to 17 and 23 to 30 min after the end of sampling. The corresponding formulas are provided

[en] The results of concentration measuring of ²²²Ru and its daughters and estimation of internal doses to workers in the underground buildings at Nanjing city are presented. The double filtering membrane method and Thomas method were used in the monitoring of ²²²Rn and its daughters, and the dose conversion factor was taken from the latest UNSCEAR report. Concentration distributions of ²²²Rn and its daughters were approximately log-normal. The geometric means for ²²²Rn was 40.5 Bq · m^-3 and for its daughters was 1.4 x 10^-7 J · m^-3. The equilibrium factor was 0.63. The radioactive equilibrium ratio between short-lived ²²²Rn daughters was 1:0.57:0.49. The estimation value of annual effective dose equivalent from ²²²Rn daughters to workers working at underground sites was 1.3 mSv, which was 86% higher than that of those working on ground sites

[en] Up to the present, radon and its short-lived decay products in air are usually monitored by means of a detection. But radon progeny, including RaB (²¹⁴Pb) and RaC (²¹⁴Bi) which are β and γ emitters, contribute about 90% to the equilibrium equivalent radon concentration (EECRn). Therefore, this paper introduces a new three-count technique by a β detector in the light of radioactive decay law and its boundary conditions during sampling and counting times to solve the Bateman equation. β (even low level β) instruments have been fairly popularized domestically and internationally. It can be used not only as an instrument for radon and its daughters in air, but also as a monitor for β airborne activity in the environment. This new method taps further the latent power of the present instrument and realizes various uses for a unit. (author)

[en] It is known that the detection efficiency must be measured with a standard source of corresponding nuclear element. But it is very difficult for radon daughter because the standard source is not available for short half life. A new method for measuring the efficiency of radon daughter by means of a field sample is detailed. Assuming that the detection efficiencies for α-particles of different energies are equal when the distances between the detector and the source are zero, the detection efficiency of radon daughter for one standard source can be calculated on the basis of radioactive decay law. It effectively solves the difficult problem mentioned above

[en] The formula of Markov method for calculating radon and its short-lived decay products concentrations in measured air by means of gross α-counting method is detailed according to the boundary conditions to solve Bateman equation from radioactive decay law. The concentration ratio of radon daughters are 1:0.6:0.4. Up to now, radon and its daughters in air are monitored usually by means of gross α-counting method. They can be measured by gross β-counting method of course. The β (even low level β) unit has popularized fairly in internal and external right now. Therefore a new Markov method by gross β measurement was advanced

[en] Up to now, radon and its short-lived decay products in air are monitored usually by means of α detection. But, radon daughters RaB and RaC which are β emitters contribute about 90% for equilibrium equivalent radon concentration (EECRn). Therefore, the paper advances a new three-count technique by a β detector. It can be used not only as a unit for radon and its daughters, but also for monitoring of β airborne activity in environment. Right now, β (even low level β) units have popularized fairly in internal and external. For this reason, the new method gives full contributions to the potential of present unit, and realizes multiple uses for a unit