Evolving problems in optimizing radiological protection: The case of internal contamination

From plant design to the operational stage several factors should be taken into account in general optimization of radiological protection against internal contamination: plant layout, containment of the material, workplace cleanliness, planned and accidental exposures, staff training, operational procedures, monitoring, etc. Formal quantitative procedures such as cost-benefit analysis or multicriteria analysis could be useful in the design stage; however, during operation the optimization can be performed only qualitatively, on the basis of experience and common sense, in order to take further measures to reduce exposures to a reasonable level. Factors such as the number and competence of staff, the equipment for personal protection, the operating procedures and the monitoring instruments can hardly be assessed in formal procedures, since they are to some extent dependent on human factors. An application of the optimization principle to the design and operation of laboratories for unsealed radioactive material is discussed in the paper. The interplay of the aforementioned factors is analysed, for a balance between the intrinsic protection assured by the premises and the equipment for material containment ('hardware protection') and protection based on the use of protective clothing or operational procedures. The tradeoff between individual and collective doses is also analysed, together with the methodologies for selecting the values of reference levels in the monitoring programmes, to be considered as indicators of whether the protection levels selected are being respected. (author)