Estimation of Radon Potential in the Pacific Northwest Using Geological Data.

摘要

Aerial gamma-ray data covering an area from 41 to 49 degrees north latitude and 108 to 125 degrees west longitude were compiled to produce a map showing the distribution of radium ((sup 226)Ra) in near-surface materials in the Bonneville Power Administration service area covering Washington, Oregon, and Idaho, and parts of Montana and Wyoming. Northern parts of California, Nevada, and Utah also show on the map. A comparison of measurements of indoor concentrations levels of radon ((sup 222)Rn) in homes with the apparent surface concentration of radium shows that aerial gamma-ray data provide a first order estimate of the relative amounts of indoor radon for township-sized areas where soils have low to moderate permeability. The comparison also shows areas with significantly higher indoor radon levels than the general trend of the data. These unusually high areas are almost all characterized by soils that have higher intrinsic permeabilities, based on available count soil descriptions. The greatest permeability effect occurs for drier soils in the eastern part of the area. Some unusually high areas are also characterized by steep slopes. Eighty soil surveys for Washington, Oregon, Idaho, and Montana were examined for the presence of highly permeable soils and a map showing large areas of highly permeable soils for the counties studied was created. 33 refs., 14 figs.