The Research on Passive and Integrated Thoron Exposure Monitoring Techniques

Both radon and thoron exposure monitoring method at the same time, and thoron exposure only monitoring method with absorber discriminating radon are developed. A simple calibration system is developed too. When radon and thoron exposure are measured simultaneously, two same dosimeters with different filter materials have the different diffusion rate constants λ d, and are of different response factors for radon and thoron. The lower limits of detection are 0.74 and 1.25 kBq·m -3 ·h for radon and thoron exposure measurement, respectively. When both a piece of 45 μm thick aluminium film and 10 μm thick PE preservation film are placed on CR-39 SSNTD, all α particles emitting from radon and its daughters are absorbed, only a part of α particles emitting from 212 Po(ThC′) can be recorded by CR-39 SSNTD. The lower limit of detection for thoron exposure measurement is 22.1 kBq·m -3 ·h._