Importance of uncertainties in dose assessment to prove compliance with radiation protection standards

Quantification of radiation protection measures is based upon prospective limitation and retrospective assessment in terms of dose, but executed often in auxiliary quantities as dose rate or activity concentration. One key issue is, however, not considered at all in standards: how to handle uncertainties resulting from assessment. Limiting quantities (as annual dose of an individual) are expressed as a single even number and hence without any explicit uncertainty and give the impression that they are most precise, although they are rounded numbers or default values. Results of measurements are mostly in terms of auxiliary quantities and have to be converted to a limiting quantity and expressed by a number and a confidence interval, which is often very large because of technical reasons. In international standards, limiting quantities and operational quantities were coined. There is a large number of possible definitions of dose, but clarity and applicability is not proportional to the number of different quantities already created. This is influenced by the fact that a quantity is defined to fulfil a certain well quantities are used to demonstrate compliance with limits, no only the number, but also the uncertainty has to be considered in an appropriate manner. The hierarchy of limiting quantities has to be taken into account in accepting a given uncertainty. The acceptable uncertainty is, however, dependent on the relation of the figure to the limit. When derived quantities are used to prove compliance, biasing optimisation by applying over conservative as well as disregarding uncertainties contributing factors. For these reasons, standards have to include information to which extent an uncertainty is acceptable in dose assessment to prove compliance with limits, where the hierarchy of limits has to be taken into account. The paper discusses some possible approaches. (Author) 10 refs