Technical documents to aid decision making for the off-site responses to major nuclear accidents during the intermediate and late phases

Laboratory of Environmental Modelling, Department of Laboratory Research, Division of Environmental Protection, Institute of Nuclear Protection and Safety, CE Cadarache, 13108 Saint-Paul-lez-Durance cedex, France

Abstract

When managing the intermediate and late phases following the release of radioactivity to the environment after a major nuclear accident, decision makers need material to support the advice they give to the authorities, and communications issued to the media. In order to document and justify their decisions, they can potentially use a wide range of tools and types of information. However, the experience gained during emergency exercises shows that only a few documents are operationally used, and such documents are often the same: cartography of deposits, spatial evolutions of doses, spatial evolutions of concentration in milk, leafy vegetable and beef meat, associated evolutions through time, population concerned and location of dwelling places, quantity of major agricultural products concerned, land use in contaminated areas.

Deposits should be broken down per radioactive nuclide. For doses, a link with the consequences of the emergency phase should be kept through the account of the radiological impact due to the exposure to the radioactive plume.

Generally, the most illustrative documents are maps and time dependent graphics, as a way to get at the same time a synoptic view of the direct consequences of the accident, the influence of some crucial phenomena (radioactive decay), and the potential consequences of mitigation actions on the field, added to the attempt at interpreting their interplay for the best management of the situation. From some examples taken during crisis exercises, we shall see what such documents with which decision-makers can made their decisions, and justify their rationale, are.