Developing Risk-Based Cleanup Levels for Radionuclides Using Two Regulatory Approaches. A. F. Eidson, IT Corporation, Houston, TX; S. Duce, IT Corporation, Knoxville, TN; and W. Schaal, IT Corporation, Martinez, CA
Cleanup concentrations are routinely calculated to support closure of sites contaminated with radionuclides. Cleanup levels for radionuclides are readily calculated with the widely used RESRAD computer program. This program, developed by Argonne National Laboratory for the Department of Energy (DOE), calculates cleanup levels to meet regulatory radiation dose limits and has been used at numerous DOE and commercial facilities. The Environmental Protection Agency (EPA) Region 9 has developed the RISKCALC computer program to develop cleanup levels according to specific EPA Superfund cancer risk assessment guidance. The presence of both radionuclides and hazardous chemicals in soil at one former Federal facility prompted a comparison of the risk-related RISKCALC-derived cleanup levels to the dose-related RESRAD-derived cleanup levels. The two approaches were found to have significantly different assumptions related to calculation of radiation dose and decay daughter contributions over time. Although it is possible to derive a single set of radionuclide cleanup levels consistent with both approaches, the values reflect major uncertainties. Consequently, it was concluded that derived dose-based cleanup levels are more readily accepted by regulators because Federal agencies and most states limit radiation exposure with specified radiation dose limits. This paper compares the two programs and discusses the impact on site remediation.
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