DETERMINATION OF THE ACTIVITY SIZE DISTRIBUTION OF RADON PROGENY

There has been significant progress in techniques for the determinatio n of the activity size distribution of radon progeny. Despite this pro gress, many inconsistencies still exist with respect to the activity d istribution, especially in the smaller particle size range. The aim of this work is to evaluate a measurement technique for determination of the activity size distribution of radon progeny, and to investigate t he effect of different screen configurations and different deconvoluti on procedures. The measurements were performed in a large experimental chamber, using three different sets of Wire Screen Diffusion Batterie s (WSDB) constructed for these studies. Aerosol concentration and size distribution in the chamber were monitored by a scanning mobility par ticle sizer. The Twomey and Reconstruct deconvolution methods were use d to derive the activity particle size distribution from the diffusion battery data. Investigations of activity size distribution using thre e WSDB sets of different sensitivity ranges showed that the distributi ons calculated with the Reconstruct program correlate well for each ba ttery set. It has also been demonstrated that while application of nar row spectrum battery sets sensitive to particular narrow size ranges c ould provide better results for these ranges, results obtained with th e battery set which covers the whole spectrum are, in fact, close to t hose for narrow spectrum sets. (C) 1997 American Association for Aeros ol Research.