An experimental analysis of some of the factors affecting gross alpha-particle activity with an emphasis on 226Ra and its progeny.

Research paper by Michael F MF Arndt, Lynn E LE West

Indexed on: 16 Jan '07Published on: 16 Jan '07Published in: Health physics


This work presents an experimental investigation of the measurement of the gross alpha-particle activity of water samples by EPA Method 900.0. The residue produced in Method 900.0 is modeled by a BaSO4 precipitate distributed over a planchet. The dependence of the gross alpha-particle activity on the activity of Ra and its progeny, on the residue mass and geometry, and on the time between sample preparation and analysis is studied. It is shown that these factors can cause the gross alpha-particle activity of a sample to vary by more than a factor of three for replicate samples and to significantly overestimate the alpha activity of the residue. For a given sample geometry, the gross-alpha particle activity generally increases as the residue mass increases owing to the presence of the radium progeny.