ICRP publication 109. Application of the Commission's Recommendations for the protection of people in emergency exposure situations.

This report was prepared to provide advice on the application of the Commission's 2007 Recommendations. The advice includes the preparedness for, and response to, all radiation emergency exposure situations defined as: 'situations that may occur during the operation of a planned situation, or from a malicious act, or from any other unexpected situation and require urgent action in order to avoid or reduce undesirable consequences'. An emergency exposure situation may evolve, in time, into an existing exposure situation. The Commission's advice for these types of situation is published in two complementary documents (that for emergency exposure situations in this report, that for existing exposure situations following emergency exposure situations in a forthcoming report entitled 'Application of the Commission's recommendations to the protection of individuals living in long-term contaminated territories after a nuclear accident or a radiation emergency'). The Commission's 2007 Recommendations re-state its principles of justification and optimisation, and the requirement to protect against severe deterministic injury, as applying to emergency exposure situations. For the purpose of protection, reference levels for emergency exposure situations should be set in the band of 20-100 mSv effective dose (acute or per year). The reference level represents the level of residual dose or risk above which it is generally judged to be inappropriate to plan to allow exposures to occur. The Commission considers that a dose rising towards 100 mSv will almost always justify protective measures. Protection against all exposures, above or below the reference level, should be optimised. More complete protection is offered by simultaneously considering all exposure pathways and all relevant protection options when deciding on the optimum course of action in the context of an overall protection strategy. Such an overall protection strategy must be justified, resulting in more good than harm. In order to optimise an overall strategy, it is necessary to identify the dominant exposure pathways, the time scales over which components of the dose will be received, and the potential effectiveness of individual protective options. If, in application of an overall protection strategy, protection measures do not achieve their planned residual dose objectives, or worse, result in exposures exceeding reference levels defined at the planning stage, a re-assessment of the situation is warranted. In planning and in the event of an emergency, decisions to terminate protective measures should have due regard for the appropriate reference level. The change from an emergency exposure situation to an existing exposure situation will be based on a decision by the authority responsible for the overall response. This transition may happen at any time during an emergency exposure situation, and may take place at different geographical locations at different times. The transfer should be undertaken in a co-ordinated and fully transparent manner, and should be understood by all parties involved.