The rapid identification of NORM discharges requiring regulatory control. A possible screening methodology

The European Commission (EC) is mindful of the potential difficulties for national regulators in implementing a process of regulatory control as set out in Title VII of EU Council Directive 96/29/Euratom (Basic Safety Standards Directive) for NORM industries discharging into the environment. As a consequence, the EC commissioned a study to identify possible procedures for the rapid identification of such industries or work activities where members of the public are potentially exposed, with a view to producing guidelines. The results of the study are presented in this paper. It is well understood that there is no simple relationship between discharge rate from a NORM industry and dose to members of the public. However, with respect to regulatory control, a detailed site-specific analysis may not be warranted when, on the basis of a conservative approach, it can be concluded that the discharges are of no radiological significance. This introduces the idea of NORM discharge screening levels which may be defined as estimates of the amount of activity discharged to the environment, which, if not exceeded, mean that it is very unlikely that members of the public would receive an effective dose above a defined dose criterion. NORM discharge screening levels can be defined for each NORM release route and would be calculated using deliberately cautious assumptions. The derivation of such screening levels would comprise the following steps: definition of reference discharge situations; choices of models, exposure pathways and parameters; derived doses per unit discharge rate; dose criteria for screening levels and finally, discharge screening levels. In this paper, discharge-screening levels are derived and presented. It is unlikely that below these levels a more detailed site-specific radiological assessment of the discharges would be warranted. It is recommended that a dose criterion be chosen for the screening level that is below the dose constraint for the facility. If discharge-screening levels are exceeded it is recommended that regulatory bodies verify the actual level of discharge, re-examine discharge conditions such as stack height or river flow, re-examine the existence of assumed exposure pathways and decide on the need for site-specific assessment. (author)