Direct determination of /sup 222/Rn gas using the electret to remove daughters at formation. Annual progress report, June 1, 1981-May 31, 1982

Description/Abstract

This report covers progress made from 1 June 1981 to 31 May 1982 in developing a continuous monitor which measures only /sup 222/Rn without interference from the daughters. Five /sup 222/Rn counters have been built which determine /sup 222/Rn alone by alpha scintillation counting in the presence of an electret to remove the short-lived daughter products from the counting chamber. The chamber design is based on the work of Chittaporn et al., (1981) at New York University's Department of Environmental Medicine. The detection chamber is a 1.8 liter (12.7 cm diameter by 14 cm high) cylinder lined with zinc sulfide alpha phosphor. The detector sits directly on a 12.7 cm diameter phototube. The 5 units have calibration factors which range from 155 to 186 counts/hour per pCi /sup 222/Rn/liter and an average background count of 6 counts/hour. The lower limit of detection for a one hour count is thus 0.03 pCi /sup 222/Rn/l, well below environmental levels.