CHARACTERIZATION OF AIRBORNE RADIOACTIVITY IN AN AUSTRALIAN DWELLING

The Australian Radiation Laboratory is undertaking a programme of meas urements in Australian dwellings using wire screen diffusion batteries (DB) and serial graded screen arrays (GSA) to characterise the indoor conditions. This paper briefly describes their operation and gives th e results of trial measurements in the study and kitchen of an occupie d house in a semi-rural location near Melbourne. Analysis of the DB an d GSA data produced an activity median diameter (AMD) for the PAEC acc umulation modes in the range 300 nm and 550 nm, under normal condition s and between 100 nm and 200 nm following combustion processes. The co rresponding values of AMD for the ultrafine modes were between 0.5 nm and 12 nm prior to the introduction of the combustion sources. The use of alpha spectroscopic methods allows the DB/GSA sizing technique to be extended to radon levels less than 20 Bq.m(-3).