Plate-out of radon daughters on large surfaces

A study has been conducted on the plate-out of the short-lived decay products of radon on large surfaces of different materials. Experiments were conducted in a Radon/Thoron Test Facility (RTTF) of the walk-in type under laboratory-controlled conditions. Samples of different materials were exposed to radon/radon daughter atmospheres for periods of time long enough for surface activity equilibrium conditions on the material to be reached. Experiments wee also done when an electrical potential was applied to some metals. The samples were examined by alpha- and gamma-spectroscopy, and by gross beta- and alpha-counting. The data show significant differences for different materials. This study is relevant in the determination of radiation levels in underground uranium mines where radon daughter plate-out on mine walls under turbulent air flow conditions, in areas of low aerosol concentration, become important