Life-Cycle Emissions Analyses

Nuclear energy stations do not emit criteria pollutants or greenhouse gases when they generate electricity, but certain processes used to build and fuel the plants do. This is true for all energy facilities. Nuclear energy’s life-cycle emissions include emissions associated with the construction of the plant, mining and processing the fuel, routine operation of the plant, disposal of used fuel and other waste byproducts, and decommissioning.

http://www.nei.org/Issues-Policy/Protecting-the-Environment/Life-Cycle-Emissions-Analyses