Nuclear Power like other forms of Energy cannot be defined by a single cost as nuclear power plants differ in their technology and sources of fuel.No two power plants can have the same cost of electricity production similarly nuclear energy plants cannot have the same kilowatt hour cost.However nuclear energy is known for its very low costs of 2-3c/kilowatt hour which can only be currently be met by coal.But nuclear energy cost is based on older nuclear power plants which have already been depreciated.This cost is also controversial as the costs of nuclear waste storage is generally not included.USA and Japan which are the largest nuclear power producers have not constructed permanent nuclear waste storage sites despite accumulating thousands of tons of nuclear waste.Also these days extra safety measures are being taken due to the Fukushima disaster which means that the costs of nuclear energy is going up.