A small volume radon progeny aerosol control device and its performance

BackgroundNuclear sites require monitoring of artificial radioactive aerosols, but existing instruments often encounter the problem of "measurement uncertainty (radon progeny interference)" in the measurement of artificial radioactive aerosols, requiring effective calibration of radon daughter interference levels.PurposeThis study aims to accurately calibrate the radon progeny measurement instruments and effectively calibratt the radon progeny aerosol interference levels for artificial radioactive aerosol monitoring instruments.MethodsBased on the behavior patterns of aerosol particles and radon along with its progeny, a small volume radon progeny aerosol control device was developed, which was composed of aerosol dilution loop, radon progeny regulation loop, and controller with programmable logic controller (PLC) control system. In the aerosol dilution loop, varying concentrations of carrier aerosols was achieved by utilizing a circulating pump in conjunction with a aerosol generator. In the radon progeny regulation loop, different levels of radon sources were employed to achieve regulation of radon activity concentration. Radon progeny aerosol with stable radon progeny state parameters was achieved by adjusting the radon concentration, aerosol concentration and air exchange rate, and the performance of this device was verified by experiments.ResultsExperimental results show that the stable regulation range of equilibrium equivalent concentration (EEC) is 3.3×102~9.4×103 Bq∙m-3, stable regulation range of equilibrium factor: 0.12~0.58, stable regulation range of unbound fraction: 1.4%~62.7%. The variation range of EEC within 4 h is within 10%, and the relative standard deviation of the uniformity experiment is less than 7%.ConclusionsThe stable regulation range of the radon progeny state parameters of the small volume radon progeny aerosol control device proposed in this study is wide, and the uniformity and stability of the radon progeny are good. It can be used to effectively simulate the field measurement environment, achieving the development purpose of this device.