Operational intervention levels for enabling the transition from an emergency exposure situation to an existing exposure situation following a radiological emergency involving release of radioactive material in the environment

Abstract

Experience has demonstrated lack of preparedness at national levels to manage the consequences of a nuclear or radiological emergency in its later phase which, on occasions, resulted in unjustified actions. To assist Member States preparing for this phase, the International Atomic Energy Agency (IAEA) published guidance (IAEA Safety Standards Series No. GSG-11) recommending, inter alia, for operational intervention levels (OILT) to be developed for enabling the transition from an emergency exposure situation to an existing exposure situation. OILT are intended to also support decisions be made on lifting or adapting public protective actions imposed early in the emergency response and on actions to be taken to further reduce exposures. Using the methodology provided therein, OILT have been calculated for radiological emergencies involving release of the most commonly used alpha, beta and gamma emitting radionuclides in the environment. In addition, an approach for deriving a default OILT value has been presented and a default OILT value for the ambient dose equivalent rate at 1 m above ground level has been derived. The derived OILT values support the application of relevant IAEA safety standards (i.e. No. GSR Part 7 and No. GSG-11) as well as relevant recommendations of the Council Directive 2013/59 in relation to the transition from the emergency exposure situation to an existing exposure situation at national levels. However, they need to be integrated within the national protection strategies to guide the implementation of activities and actions that support the resumption of normal social and economic activity after the emergency which include those concerning return of members of the public, who were resettled during the implementation of evacuation or relocation, to their homes.