EVALUATION OF ACTIVATED CARBON CANISTERS FOR RADON PROTECTION IN URANIUM MINES

摘要

The protection against radon gas afforded by several types of activated carbon gas mask canisters was determined, since uranium mine personnel are occasionally exposed to radon concentrations in the thousands of pCi/l range, and calculations showed that 3300 pCi/l of radon was equivalent to the permissible level of 0.3 WL of radon daughters on the basis of potential alpha energy release in the respiratory tract. The canisters were tested at radon concentrations from about 1500 to 40/000 pCi/l and flow rates from 8 to 64 l/min. Other variables studied were test air humidity, water content of the carbon, and temperature. Results indicated that a canister containing about 900 ml of dry, high-grade activated carbon, used at a breathing rate of 16 l/min, would provide almost 100% protection against radon for a period of one hour at a temperature of 25°C and an air humidity of about 9 mg/l. Protection would be provided for a longer period at the lower temperatures existing in uranium mines.