There are presently 99 nuclear power plants licensed to operate in the United States. They are exclusively of two types, boiling-water nuclear reactors (BWR) and pressurized-water nuclear reactors (PWR). Of those 99, 65 are PWR's and 34 are BWR's. Together, they generate approximately 20% of the electricity used in the U.S.

When Unit 2 of the Dresden Nuclear Power Plant was activated in 1970, it had cost the owning utility, Commonwealth Edison, a modest sum, compared with what was soon to come. Fourteen years later plants had construction costs over 10 times as much and took many years longer to build. The burden of construction became the overriding concern for utilities in considering the option of using nuclear energy to generate electricity. This type of costly experience (plus the accidents at Three Mile Island and Chernobyl) effectively ended nuclear power plant construction for many years in the USA.