An analysis of efficient measurement procedures for radon progeny

Abstract

Efficient measurement procedures for 222Rn- and 220Rn-progeny are needed for dose mitigation in the important field of indoor radiation exposure. Practical and instrumental measurement parameters are discussed. In the light of these, the measurement efficiency of batch and continuous sampling procedures for individual radon progeny, including flow-through, alpha spectrometric and beta measurement, was investigated. Measurement standard deviations were derived at normalized progeny concentrations, flow-rate, and collection and detection efficiencies. These can readily be converted to other than the chosen normalized conditions. The standard deviations and total procedure time are useful indications of measurement efficiency. Combined beta/alpha detection with modern Si detectors offers greatly improved measurement efficiency over conventional alpha detection, which is advantageous particularly when measuring generally low environmental radiation levels. This combination makes feasible much shorter total times for batch procedures or shorter time differentiation for continuous procedures and far more convenient, portable instruments. For 222Rn progeny and mixtures with 220Rn progeny, similar advantages are attained over alpha-only procedures.