The USA is the world's largest producer of nuclear power, accounting for more than 30% of worldwide nuclear generation of electricity.
The country's 100 nuclear reactors produced 798 billion kWh in 2015, over 19% of total electrical output. There are four reactors under construction.
Following a 30-year period in which few new reactors were built, it is expected that four more new units will come online by 2021, these resulting from 16 licence applications made since mid-2007 to build 24 new nuclear reactors.
Government policy changes since the late 1990s have helped pave the way for significant growth in nuclear capacity.
Some states have liberalized wholesale electricity markets, which makes the financing of capital-intensive power projects difficult, and coupled with lower gas prices since 2009, have put the economic viability of some existing reactors and proposed projects in doubt.