The electricity output from nuclear power generation varies across the World, with many of the larger developed countries already producing considerable capacity.
The USA, as at Dec 2012, was the World’s largest nuclear power generator. The following table shows nuclear power generation by country. The UK can be seen at number 11 in the table. Interestingly, 10 of the top 15 producers are classified as developed by FTSE (an equity index provider).
However when you look at nuclear power generation capacity under construction at the same date, in the following table, you can see that the majority (10 of the top 15) are classified as emerging by FTSE.