Influence of sampling air flow rate in the decay correction applied to the determination of 7Be and short-lived radionuclides in aerosol samples

An original decay correction procedure is proposed for the activity determination of short-lived radionuclides in airborne dust samples. To this end, the hypothesis of air flow rate attenuation during sampling is considered and tested. The other decay corrections: to the delay time, from the end of the sampling until the start of the counting; and to the counting time, were executed as standard. Differences from classic corrections, which consider a constant air flux rate in the sampling with a weekly sampling duration, are of the order of 1% for 7Be and approximately 10% for 131I. Moreover, the procedure can be applied to estimate the air volume sampled in the last 24 h before the end of the sampling. This volume can be used to calculate the activity concentration of a radionuclide (short-or long-lived radionuclide) if a major nuclear accident causes an instantaneous contamination immediately before the end of sampling.