Although nuclear power is considered a form of low-carbon power, its legal inclusion with renewable energy power sources has been a subject of debate and classification. Statutory definitions of renewable energy usually exclude many present nuclear energy technologies, with notable exceptions in the states of Utah, and Arizona in the United States, where only a particular implementation of nuclear fission with "waste"/fuel recycling meets the state's criteria. Dictionary sourced definitions of renewable energy technologies often omit or explicitly exclude mention to every nuclear energy source, with an exception made for the natural nuclear decay heat generated within the Earth/geothermal energy.
The most common fuel used in conventional nuclear fission power stations, uranium-235 is "non-renewable" according to the Energy Information Administration, the organization however is silent on the recycled fuel of MOX. Similarly, the National Renewable Energy Laboratory does not mention nuclear power in its "energy basics" definition.
In 1987, the World Commission on Environment and Development (WCED) classified fission reactors that produce more fissile nuclear fuel than they consume (breeder reactors, and if developed, fusion power) among conventional renewable energy sources, such as solar and falling water. The American Petroleum Institute likewise does not consider conventional nuclear fission as renewable, but that breeder reactor nuclear fuel is considered renewable and sustainable, and while conventional fission leads to waste streams that remain a concern for millennia, the waste from efficiently burnt up spent fuel requires storage for no more than a thousand years. The monitoring and storage of radioactive waste products is also required upon the use of other renewable energy sources, such as geothermal energy.