Abstract In papers by Häfele, Manne and Schikorr, strategies for a transition from fossil to nuclear fuels are considered for a model society of 250 M people with an asymptotic energy consumption of 10 kW thermal per capita. In the final state, a purely nuclear energy production system, based on only two reactor types, was assumed to cover all electric and non-electrical energy demands of the model society. It is the purpose of this paper to evaluate the whole nuclear fuel cycle belonging to the asymptotic nuclear energy-production system. In order to achieve this, all normal operational and accidental risks connected with the nuclear material throughputs are analyzed. Thus, an idea of the relative importance of the different hazards is obtained; furthermore, the basis for a comparison of the nuclear option with alternative options (which is the subject of forthcoming work) is given. With this purpose in mind, only orders of magnitude are considered throughout the paper; in addition, the argumentation is restricted to the level of expected values. Following the introduction, the mass flows of nuclear material through the nuclear fuel cycle are analyzed. The methodology used is then developed. The normal operation releases of radioactivity are considered and possible modes of accidental radioactive releases are analyzed; the problem of a final waste storage is treated separately because of its unique nature. Different kinds of sabotage and blackmail, including the construction of a nuclear explosive device, are next analyzed; finally, all calculations are summarized. In conclusion, a number of decision-oriented assessments are identified that must be made when the large-scale deployment of nuclear energy is considered.