Approach toward development of release standards for D and D cleanup

The release of materials containing residual radioactivity from a controlled environment in decontamination and decommissioning (D and D) activities has been problematic. The primary impediment to such a release is the lack of a suitable framework within which release standards can be developed. The concept of clearance for radioactive materials was recently introduced by the International Atomic Energy Agency (IAEA) (l). This concept is being evaluated by the international regulatory communities as a basis for setting standards for releasing from control solid materials containing residual radioactivity. Accordingly, both the IAEA (2) and the European Commission (EC) (3) have recently proposed clearance standards. In the US, the Nuclear Regulatory Commission (USNRC) has just begun its rule-making process on clearance. The term ''clearance'' was introduced as a regulatory process for releasing radioactive materials posing negligible risks. A trivial risk level has been determined to be a 10-6 to 10-7 annual risk to an exposed individual, and a population risk of no more than 0.1 for an annual practice. Under these strict constraints, exposure scenarios would be developed to estimate potential doses to affected individuals. Such scenarios may account for processing, disposal, and product end-use of materials. This paper discusses these scenarios and also describes the technical basis for deriving release levels under the suggested risk for dose constraints