A study on 85Kr measurement with an internal gas proportional counter.

A measurement method of 85Kr using an internal gas proportional counter (IGPC) is presented in this study. The operation conditions of the IGPC were determined and optimized, including the operating voltage, pressure, sample volume, interference from other gas components such as nitrogen or air, and mitigation of the memory effect. The IGPC was calibrated using certified standards, and the detection efficiency was approximately 58% for typical samples. A lower limit of detection of approximately 0.11 MBq/m3(Kr) was achieved after counting for 5 h with 1 mL pure Kr, corresponding to the atmospheric activity concentration of 0.18 Bq/m3 (air). It was shown that the IGPC could be used effectively for measuring 85Kr.

A correlation study of continuously monitored gamma dose rate and meteorological conditions.

In this paper, the correlations between the continuously monitored gamma dose rate (GDR) and meteorological parameters, including precipitation, air temperature, relative humidity, air pressure, wind direction, and wind speed, were analyzed by using one year of the hourly dataset from a monitoring system with ten stations. The correlation coefficients are varied by the range of each meteorological parameter. Precipitation would enhance the GDR up to 84%, which is highly related to precipitation intensity and ground type. Strong and positive correlation between the GDR and light precipitation was identified, while the correlation was reduced with increasing of precipitation. Air temperature could cause a fluctuation of the average GDR within the range 1.8-5.3 nGy h-1, and different correlation characteristics were indicated for low and high air temperature. The GDR was positively correlated with relative humidity, though relative humidity is inversely correlated with air temperature. Correlations between the GDR and air pressure were mainly negative. Diurnal variations between the GDR and the air temperature, relative humidity, and air pressure were also analyzed. The wind played an important role also in the fluctuation of the GDR with the GDR difference up to 2.00 nGy h-1 averaged from the sixteen wind-directions. Lower GDR can be found in the direction of prevailing wind because of the dilution effect of the radon progenies in the surface air. In this paper, some exploratory interpretation of physical influence mechanisms of meteorological parameters on the GDR was also presented, which suggests further work should be carried out to explore the variation and correlation principle.