Analysis of 228Ra and 226Ra in public water supplies by a gamma-ray spectrometer.
Methods for measuring 228Ra were reviewed to select a brief and simple screening procedure under NIPDW Regulations for public water supplies. A two-step method was considered to concentrate Ra by evaporation or co-precipitation and to count it with a gas ionization detector, a liquid-scintillation detector, or a Ge detector with multichannel analyzer. Gross beta particle counting appears to be feasible for screening to meet the 0.04 Bq L-1 detection limit. One can utilize the same sample volume as currently collected and measure radiation with commonly available equipment in reasonable time. The required sample volumes were estimated on the basis of known counting efficiencies and background count rates. Gamma-ray spectral analysis is the recommended option, however, because 226Ra and 228Ra can be determined directly and simultaneously. Several aspects of the method were examined to assure that the concentration procedure is nearly quantitative and that the detection limit can be reached with a 3.8-L sample in a 6000-s counting period. The method was tested with Ra tracer solutions and EPA intercomparison samples over the range of 0.04 to 1 Bq L-1. It was found appropriate for 228Ra and 226Ra analyses.
Kahn
B
B
Nuclear Engineering and Health Physics Program, School of Mechanical Engineering, Georgia Institute of Technology, Atlanta 30332.
Rosson
R
R
Cantrell
J
J
D011883:Radium / Q000032:analysis*; D013051:Spectrometry, Gamma / Q000379:methods*; D014878:Water Pollution, Radioactive / Q000032:analysis*; D014881:Water Supply / Q000032:analysis*
D011883:Radium