ENVIRONMENTAL CLEANUP CRITERIA DEVELOPED FOR RADIONUCLIDES IN SOIL AT U.S. DEPARTMENT OF ENERGY SITES

摘要

More than 100 U.S. Department of Energy sites throughout the United States require environmental remediation for contaminants from processes used primarily in the nuclear weapons program and the nuclear fuel cycle. These sites encompass almost 10,000 individual geographic areas. It is estimated that under current processes it will cost about $200 billion dollars over the next 70 years to remediate and monitor these areas. Cleanup criteria are the maximum residual concentrations of individual contaminants that will remain in environmental media or facilities after remediation has been completed. Cleanup criteria are presumably consistent with risk- or dose-based goals. The selection of cleanup criteria is an intricate process that takes into account factors such as projected site usage, numerous federal, state, and local requirements, and stakeholder concerns. An Internet-accessible database was established by the U.S. Department of Energy Office of Environmental Management to record agreed on values of cleanup criteria. Currently, it includes data from about 300 individual areas. This paper presents examples from this database to show the range of cleanup criteria for ~(137)Cs, ~(238)Pu, and ~(90)Sr contamination in soil. The data illustrate that, in some cases, the cleanup criteria agreed on for a single radionuclide can vary by orders of magnitude for the same land use scenario. This variation can be attributed to a number of factors, including physical conditions that contribute to differences in the results for pathway analyses for the same risk or dose goal (such as the presence of multiple contaminants or variations in local climate and geography). In many cases, however, input from regulators and stakeholders is likely to be the most significant factor. The development of appropriate cleanup criteria is crucial to cost-effective remediation. By providing a means of identifying site cleanup levels, the database can be a useful tool in the process of comparing cleanup criteria for individual contaminants across the DOE complex.