Corrections to Kusnetz method for measurements of radon progeny concentrations in air

In 1956, H.L. Kusnetz proposed a quick method for radon progeny concentration measurement in mine atmosphere using single gross-alpha count of membrane-filtered air. The is still widely used today and based on number impractical assumptions. An instantaneous sampling time (less than ten seconds), one these assumptions that ignores the build-up decay filter paper during period. Of special concern 214Bi period, since 214Po alphas are lost cannot be accounted counting time. addition, assumes activity period constant. This inaccurate assumption can result smaller rate, especially when times long. Hence underestimated working levels expected factors without correcting times. this technical report, exact corrections to provided along with updated correspond common equilibrium conditions correctly estimate Working Level Additionally, commonly self-absorption correction formula lower level detectability (LLD) equation any sample given.