RDS has commissioned a low-background monitoring method that uses the RDS medium-flow-rate air sampler (MFRAS) coupled with a filter cassette, powered by battery and solar technology. The method employs a flow rate of 1.5 L/min and the RDS Low Background Alpha Counter for analysis.
Sampling uses glass-fibre or membrane filters to collect airborne particles containing naturally occurring alpha emitters, typically over 1 to 4 weeks. Counting occurs at least five days after sampling to minimise the contribution of short-lived radon decay-series products.
The system achieves a background count rate at least 5–10× lower than typical commercially available alpha counters, making it well suited for uranium and mineral-sand mining monitoring. The method can additionally measure radon daughters using the Kodak LR-115 nuclear-track detector film.