This study aims to evaluate and estimate the environmental impacts of nuclear fuel cycles and to support the decision-making of nuclear energy policy, relating to a selection of environmentally preferred nuclear fuel cycle for the environmentally sound and sustainable development of nuclear energy. To achieve this objective, life cycle assessment (LCA) as an environmental management tool is applied to the nuclear fuel cycle alternatives of a once-through fuel cycle, the direct use of PWR spent fuel in CANDU (DUPIC) cycle and recycling with plutonium and uranium recovery by extraction (PUREX) process. The assessments provide a comparison of the environmental impacts of the three nuclear fuel cycle options and the environmentally most significant stages of each nuclear fuel cycle are identified. As a result, the recycling with PUREX process turned out to impose less-significant environmental impact than did the DUPIC and once-through options. The environmentally dominant stage was found to be mining/milling stage and the most radiologically significant pathway could be an internal exposure. The results are useful for making a decision of nuclear energy policy by an estimation of environmental impacts of nuclear fuel cycle options and the application of LCA to nuclear energy is very significant eco-labeling according to the advent of international standard organization 14,000 series. Finally, this approach also makes it possible to obtain the environmental data relating to the nuclear energy and to examine the environmental impacts of chemical effluents discharged from a nuclear facility. From this result, therefore, the comparative assessment of nuclear and non-nuclear energy sources including radiological and non-radiological aspects may be further developed.