The acceptability of nuclear fission as energy source is governed by three factors, economic, ecological and sociological. the economic context the gradual exhaustion of fossil fuels is a result of ever-increasing demands. The biological risk concept which determines the acceptable industrial application level is the second factor to be considered. The danger of radioactive contamination is almost unexistent except in the accident hypothesis, and power stations are built with excessive safeguards against hypothetical accidents. The idea of systematic processing of all working effluent to reduce radioactive waste discharge by several orders of magnitude is being examined. The only serious problems seem to be the disposal of radioactive wastes and the plutonium non-proliferation question bound up with breeder reactors. Whereas vitrification offers some solution to the radioactive waste conditioning problem, responsibility for the proliferation of nuclear weapons rests with the human conscience alone. The development of nuclear power stations over several decades seems to present no inacceptable danger and offers the best compromise betweengrowth and minimum risk requirements. The third factor to be accounted for is the opposition displayed by a fraction of the population to the development of nuclear energy for peaceful applications.