Dosimetry issues in Radiological and Nuclear Emergency Preparedness and Response

Abstract

In the case of a nuclear or radiological accident involving significant releases of radioactivity, the basis for decisions on the implementation of protective actions for the population and the emergency responders should be a good radiological characterization of the situation. In the early phase of the accident, the main concern is to decide under uncertainty whether an evacuation, sheltering or iodine thyroid blocking are required. It is necessary to have a good dose prognosis using state-of-the art models for atmospheric dispersion and dose assessment, complemented with real time data supplied by fixed radiation monitoring networks and mobile units, both terrestrial and airborne. In complex scenarios with persons potentially irradiated, decisions on their treatment would require an initial screening followed by a more detailed dose evaluation using biological dosimetry, whole body counting, in vitro measurements of biological samples and other methods. Particular attention is necessary to thyroid dose monitoring, especially for children and pregnant women. In the intermediate phase, radioactivity controls in air, food and water, and detailed characterization of the contamination levels of large areas would be necessary to decide on the termination of the urgent protective actions adopted during the early phase or on new countermeasures like food bans, decontamination of areas or relocation of people from the hottest zones. Reference dose levels for the existing exposure situation in the long-term are set in terms of residual dose, and realistic dose projection models should be employed together with monitoring data to produce a good assessment in which to base such transcendental decisions. Besides the official experts, other actors like affected citizens or local institutions may collect radiological data. Protocols should be prepared to assist in such data collection by stakeholders and to integrate them. Qualified personnel and suitable individual dosimetry systems for the public should be made available to allow people knowing their radiation exposure, including where, when and how they are exposed. Measurements of ambient exposure levels, of individual external exposures, of concentrations of radionuclides in foodstuffs and in the environment, as well as the individual internal exposure should be maintained in the long-term together with support to understand the relevance of such data, so that people can make their own protection decisions. All together, these are great challenges related to dosimetry issues which need to be duly addressed.