Measurements of ²²²Rn and ²²⁰Rn with a Large Size Collector of Radon Progeny

Radon concentrations in high background radiation areas in the south are higher than those of others in China, especially ²²⁰Rn concentration is significantly high. Therefore, measurements of ²²²Rn and ²²⁰Rn concentrations should be carried out there. This paper introduces a large size collector of radon progeny and its applications. The collector is a sheet of polyvinyl chloride fiber with electrostatics of (-500 V)-(-700 V). Its size (60 mm in diameter) is larger than those of others (26 mm in diameter) that work with the same principle. The collector is more effective to adsorb radon progeny than most of others. The equipment of ZnS(Ag) Scintillation Counting System is available for large size collectors to detect radon progeny. Therefore, its sensitivity of measurement is higher than that of others. According to the different half lives of radon progeny, and based on both theory and experiments, a formula for discrimination and calculation of ²²²Rn and ²²⁰Rn concentrations is deduced. The ²²²Rn and ²²⁰Rn concentrations were surveyed with electrostatic collectors of radon progeny on the campus of commercial school and some other areas in Hainan, southern China. Neither ²²²Rn nor ²²⁰Rn concentration was found significantly high. However, several faults underground were delineated. The collector is also used to study radon transportation. Results indicate that radon changes regularly with date when it has transported for a certain distance. Velocities of radon migration in the four media are quite different. Radon migrates more quickly in vertical tube than in the horizontal tube.