Variations in the gross alpha and beta activity in surface waters at the Atomic Weapons Establishment Aldermaston (UK)

摘要

Statistical analysis has been performed on the gross alpha- and beta-activity measurements of surface waters collected at the Atomic Weapons Establishment at Aldermaston (UK) during the period January 2002-September 2005. The results have been found to follow a lognormal distribution and this has important applications when considering gross activity exemption thresholds. This implies that the gross activity is the multiplicative product of many small independent factors, such as meteorology, flow conditions and site operations. The influence of meteorological parameters has been investigated using linear regression, and some correlation has been identified between gross beta-activity and parameters indicative of fine weather. Variations in gross activity have been considered on monthly, weekly and daily timescales and characterised using the geometric mean and geometric standard deviation in accordance with the properties of the lognormal probability density function.