Radon surveys with charcoal and liquid scintillation counting

Abstract

A detection system for indoor radon using vials with activated charcoal adsorbant and liquid scintillation spectrometry for measurement has been tested thoroughly for months during different seasons. Deviation in the results of two days of exposure from the mean value were at most about ±30%. This system was chosen for a pilot project for large area surveillance in Mühlviertel, a granitic area in the federal state of upper Austria. The distribution system of the detectors is described. The measurement of more than 1200 vials within about two weeks was possible by using ultra low-level liquid scintillation counters (“Quantulus”). The highest value observed so far was 3150 Bq/m³. Comparing the ratios of the results from the three different measurement systems (charcoal, track etch, electret) significant but acceptable differences were found not only between track etch (3 months exposure) and activated charcoal (3 days exposure), but also between track etch and electret, which both had been exposed for three months. The data are discussed regarding the dose to the population.