ASSESSMENT OF RADON POTENTIAL FOR SITE-SPECIFIC LOCATIONS ON THE MIOCENE MONTEREY FORMATION IN CALIFORNIA: A RAPID AND COST-EFFECTIVE SCREENING METHOD
Current methods for identifying radon-prone areas include the use of indoor radon measurements, geological subunit composition, and aerial radiometric data collected for the National Uranium Resource Evaluation (NURE) Program during the early 1970s. Unfortunately, due to air space restrictions, many densely populated areas where radiometric measurements would be the most beneficial were not surveyed by the NURE effort.
Though present methods depict generalized estimates for widespread areas, our recent studies demonstrate that surficial equivalent uranium (eU) concentrations can change significantly in as little as 30 feet, which can cause misleading assignments of uranium content to important geological units, and thus lead to inaccuracies in radon potential mapping. In addition, because aerial radiometric data was based on flight line grid cells of approximately 3 x 12 miles, these data lack the spatial resolution to reflect the radon potential for specific sites and densely populated neighborhoods.
The present study suggests that site-specific ground gamma-ray spectrometry measurements can be an accurate and cost-efficient method for assessing the radon potential of specific locations on the Monterey Formation. Furthermore, with appropriate supporting data, this method could be extended to other uranium-rich geologic subunits to obtain more precise risk assesments.