Detection Measurement of the Activity Size Distributions (D/sub p/ > 0.5 NM) Associated with Radon Decay Products in Indoor Air.

摘要

In this research, a system for the detection and measurement of the activity size distributions and concentration levels of radon decay products in indoor environment has been developed. The system is microcomputer-controlled and involves a combination of multiple wire screen sampler-detector units operated in parallel. The detection of the radioactivity attached to the aerosol sampled in these units permits the determination of the radon daughter activity-weighted size distributions and concentration levels in indoor air on a semi-continuous basis. The development of the system involved the design of the detection and measurement system, its experimental characterization and testing in a radon-aerosol chamber, and numerical studies for the optimization of the design and operating parameters of the system. Several concepts of utility to aerosol size distribution measurement methods sampling the ultrafine cluster size range evolved from this study, and are discussed in various chapters of this dissertation. The optimized multiple wire screen (Graded Screen Array) System described in this dissertation is based on these concepts. The principal facet of the system is its ability to make unattended measurements of activity size distributions and concentration levels of radon decay products on a semi-continuous basis. Thus, the capability of monitoring changes in the activity concentrations and size distributions as a function of both time and indoor events is now available. Future work with the system will involve field measurements of radon decay product activity size distributions and concentrations in various indoor environments. The resultant information should permit a better estimation of the potential human health hazard from the inhalation of radon decay products present in indoor air. 79 refs., 25 figs., 9 tabs. (ERA citation 14:024527)