Limiting human exposures through the ``as low as reasonably achievable`` process at a Department of Energy mixed waste site

Applying a process to reduce human exposures to levels as low as reasonably achievable (ALARA) is a cornerstone of the US Department of Energy`s radiation protection program, and this process is being used to develop cleanup levels for contaminated sites across the country. Under the ALARA process, exposures and risks are reduced as far below protective criteria as can reasonably be achieved--considering technical, economic, and social factors. Risk-based cleanup levels have been developed for radionuclides and chemicals in surface water and soil at the Weldon Spring site in Missouri, following explicit applications of the ALARA process. Among the lessons learned during these applications were the importance of three factors: (1) soliciting early input from the parties involved--because the ALARA process involves a range of technical and nontechnical issues; (2) maintaining site specificity for the ALARA analyses--because contaminant types and distributions will vary, as will local conditions and constraints; and (3) identifying cleanup levels in the planning phase that are distinct from those developed for the field phase--because remedies can be over-designed if the decision levels are the same as the ALARA goals for field work, such that little increased risk reduction is achieved for substantially higher costs.