The use of constraints by ICRP

The concept of a constraint on individual doses to be applied in the process of the optimisation of protection was included in the 1990 recommendations of the International Commission on Radiological Protection. The concept was not new, having been established at least as early as 1973. A dose constraint as understood by ICRP is not a subsidiary limit on the dose to individuals, nor is it a form of investigation level. It is a prospective tool forming an integral part of the procedure of the optimisation of protection. The choice of the magnitude of a constraint is not easy and only general guidance has been forthcoming. It is to be hoped that authorities making such choices will give open explanations of their decisions.