[en] Past milling of uranium and thorium ore in the United States has produced tailings that are stored at numerous sites around the country. Some of these storage sites are located near towns and cities, and the local populations are exposed to radiation and radioactive materials migrating off the sites. The federal government has initiated remedial action programs (for example the Uranium Mill Tailings Remedial Action Program and the Formerly Utilized Sites Remedial Action Program) to clean up land and buildings that have become contaminated with radioactive material and thus eliminate or reduce population exposure to radiation. The degree of long-term benefit from any reduction of the population dose will be different for each remedial action, as will the cost. To gain a perspective on the cost-benefit ratios of various alternatives (remedial actions), estimates are made of the potential radiation doses to affected populations near two inactive sites and of the costs associated with (1) onsite stabilization of radioactive tailings, and (2) transportation of tailings to remote locations for stabilization. The calculations presented in this paper were based on actual conditions at an inactive uranium mill tailings site (the Vitro site in Salt Lake City, Utah) and at a former thorium-processing facility (Kerr-McGee site in West Chicago, Illinois)