ASSAY OF RN-222 IN WATER SAMPLES BY A MODIFIED INTEGRAL COUNTING METHOD

Rn-222 activity concentrations in water collected from 163 private wel ls and 14 springs in Tokyo were measured with a liquid scintillation s pectrometer using a modified integral counting method. The activity co ncentrations of Rn-222 range from 0.2 to 22.9 Bq/L and average 4.8 Bq/ L. The errors due to the air luminescence counts and the interferences from Rn-220 and Rn-219 are discussed and evaluated. Rn-222 samples of 0.2 Bq/L can be assayed within an overall uncertainty of 3.1%. The li quid scintillation method involving agitation of the sample water dire ctly with a liquid scintillation cocktail was compared with the presen t method and evaluated. (C) 1998 Elsevier Science Ltd. All rights rese rved.