<P> Nuclear power plants currently operate in 31 countries . Most are in Europe , North America , East Asia and South Asia . The United States is the largest producer of nuclear power , while France has the largest share of electricity generated by nuclear power . In 2010 , before the Fukushima Daiichi nuclear disaster , it was reported that an average of about 10 nuclear reactors were expected to become operational per year , although according to the World Nuclear Association , of the 17 civilian reactors planned to become operational between 2007 and 2009 , only five actually came on stream . Global nuclear electricity generation in 2012 was at its lowest level since 1999 . </P>
where is nuclear energy used most in the world
United States