IN THE three and a half years since Hiroshima, considerable loose talk about atomic power has circulated among both scientists and laymen. At first people envisioned virtually costless power. Upon more sober reflection they realized that even if the cost per kilowatthour of the atomic fuel were to approach zero other important items in the cost of generating power would be far from zero.' But though this realization has become general, what discussion there has been of the cost of atomic power has proceeded on an elementary and unrefined basis. As yet the estimates which have been made of the costs of generating electricity in atomic stations are highly tentative. All existing nuclear piles have been constructed for non-power purposes, and there is great uncertainty about both capital and operating costs of the pile, chemical and metallurgical plants, and heat exchanger of the future atomic plant. Little if any significance, therefore, should be attached to the numerical estimates of costs of atomic power used in this paper. Our purpose is to discuss the implications of what can now be perceived about the probable characteristics of the costs of atomic power plants and to bring out certain economic relations which will be of importance when, through accumulated experience, nuclear engineers are in a position to make fairly exact cost estimates.