DETERMINATION OF WATERBORNE RN-222 CONCENTRATIONS USING AC CANISTERS

A method for measuring Rn-222 concentration in water using charcoal ca nisters is presented. Rn-222 is transferred within a few minutes from water contained in a 0.720 L bottle to a charcoal canister using a por table degassing unit. In the laboratory, gamma counting is performed a t least 10 h after sampling to determine waterborne Rn-222 concentrati on. The results obtained with charcoal canisters are compared to measu rements made with Marinelli beakers calibrated in a comparison with li quid scintillation counting. The efficiency of transferring dissolved Rn-222 in, water to activated charcoal is 99%, based on measurements m ade using Marinelli beakers. The lower limit of detection at the 95% c onfidence level is approximately 1 kBq m(-3) for a 15 min gamma count. The system was used to measure radon concentration in mineral groundw ater near Rome.