In recent years the large scale expansion of nuclear power in several of the industrialized countries of the Western world has become an issue of increasing concern to environmentalist groups, policy-makers and a number of scientists. Reports on possible inadequacies in safety precautions combined with discussions on the likelihood of theft or sabotage of dangerous materials have received wide coverage in the mass media and have caused public anxiety. Scientists have been engaged in a number of controversies which indicate areas of genuine theoretical uncertainty as well as the lack of reliable data for specifying possible future implications of differences in radiation levels and carcinogenetic effects. A continuing debate has focussed on the role of scientists qua expert, on how to weigh present and future risks against benefits, notably of an economic kind, and on how to grant access to some form of public participation in complex technological matters (1).