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Accident consequence assessment codes are used to evaluate the risks of hypothetical accidents at nuclear plants, allowing for the range of atmospheric conditions that could occur at the time of the accident. The codes include an allowance for the effect of countermeasures, such as sheltering, evacuation, and stable iodine tablets, in reducing doses following such accidents.

Uncertainty analyses have been undertaken on various aspects of the predictions of such codes. This report describes a project to use expert judgment to determine distributions on the values of some of the parameters used in countermeasure modules of accident consequence assessment codes.

In the codes, countermeasures are taken once calculated doses are above preset intervention levels (doses defined by international bodies such as the International Atomic Energy Agency - IAEA). Whether in real situations emergency managers will act accordingly is hard to predict. Uncertainties associated with these decisions are termed 'volitional' uncertainties. These uncertainties, however, cannot be assessed by expert judgments, as they express the decision at stake in an emergency situation. Uncertainties on the times to implement countermeasures and on the times for the general population to respond to these measures can be assessed by experts, as they represent 'lack-of-knowledge' uncertainties. This report describes the difference in approach of both types of uncertainties and shows the results of aggregating expert judgments on the latter type of uncertainties in early countermeasure strategies. Ten experts from seven European countries have provided subjective judgments. ts.

Additional information

Authors: GOOSSENS L H J, Delft University of Technology (NL);KRAAN B C P, Delft University of Technology (NL);COOKE R M, Delft University of Technology (NL);JONES J A, NRPB Didcot (GB);EHRHARDT J, FZK, Karlsruhe (DE)
Bibliographic Reference: EUR 18821 EN (2001), pp.180. Euro: 28.00
Availability: Available from EUR-OP sales agents. URL:
ISBN: ISBN: 92-894-2084-7
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