Derived unconditional clearance levels for materials with negligible radioactivity

Enveloping scenarios for external gamma irradiation, ingestion and inhalation have been developed to describe the radiation exposures after clearance of material with negligible radioactivity instead of defining scenarios for each of the many possible exposure situations. Using the 10 μSv per year dose constraint and the enveloping scenario which lead to the largest individual dose radionuclide specific unconditional clearance levels were calculated. Compared with the unconditional clearance levels from the IAEA the enveloping scenarios lead in general to somewhat lower clearance levels, but are nevertheless for the most part within the IAEA order of magnitude categorization scheme. (orig.)