Protective appliances must provide an effective barrier to minimize worker exposure due to inhalation or skin absorption of tritium. Permeability parameters (permeation coefficient, diffusion coefficient and solubility) of tritiated water vapor (HTO) for polymer films used for the protective appliances are essential to evaluate the effectiveness of appliances. The parameters of five plastic, six rubber and five laminate films were measured using an apparatus capable of determining the parameters precisely. The data thus obtained proved that the HTO permeability parameters did not depend on the ambient temperature, relative humidity or thickness of the films. The data also showed that the permeation coefficients of two laminate films (chlorosulfonic polyethylene+urethane+chlorosulfonic polyethylene and polyethylene+polyvinylidene chloride+polyethylene) were lower than those of respective components of the laminate films. In the laminate films, the solubilities of the inner films are higher than those of the outer ones. Furthermore, it was observed that the desiccation of HTO contaminated films for 3 or 4 days was enough to decontaminate the films, so that the films returned to their original performance.
In order to estimate the various effects of radon progeny on the gamma-ray dose rate observed at the ground surface, a computational program was newly developed for the calculation of gamma-ray dose rate at the ground surface due to radon progeny in the atmosphere around a complicated topography. The results obtained in this study are as follows. (1) Not only vertical distribution but also horizontal distribution of the atmospheric radon progeny must be considered for the accurate estimation of gamma-ray dose rate at the ground surface. (2) Important information can be obtained about the quantitative topographic effects on the gamma-ray dose rate at the ground surface that were not usually considered. Using the developed program, gamma-ray dose rate at the ground surface due to the arbitrary vertical and horizontal distribution of radon progeny in the atmosphere can be calculated taking topographic effects into account.