Using Continuous Monitors to Test the Uniformity of a Radon Chamber

The radon chamber at Bowser-Morner was designed to ensure that the concentration of radon throughout the chamber is uniform. Nevertheless, it is important to demonstrate this uniformity periodically with measurements. To that end, 36 continuous radon monitors were simultaneously deployed in the chamber in a statistically balanced pattern and were exposed for a period of 48 hours. The resulting measurements of average radon concentration were analyzed using a two-way analysis of variance (ANOVA). The results showed that any nonuniformity was not statistically significant. The radon monitors averaged 25.6 pCi/liter with a coefficient of variation (COV) of 3.4%. Other sources of uncertainty that contribute to the COV are discussed, such as the “counting statistics” during the 48-hour exposure in the chamber and the calibration process. These considerations support the conclusion that if there is nonuniformity of radon concentration in the chamber, it is so slight as to be difficult to detect.