The San Onofre Nuclear Generating Station (SONGS) is a permanently closed nuclear power plant located south of San Clemente, California, on the Pacific coast, in Nuclear Regulatory Commission Region IV. The plant was shut down in 2013 after defects were found in replacement steam generators; it is currently in the process of decommissioning. The 2.2 GW of electricity supply lost when the plant shut down was replaced with 1.8 GW of new natural-gas fired power plants and 250 MW of energy storage projects.

Nuclear decommissioning is the process leading to the irreversible complete or partial closure of a nuclear facility, usually a nuclear reactor, with the ultimate aim at termination of the operating licence. The process usually runs according to a decommissioning plan, including the whole or partial dismantling and decontamination of the facility, ideally resulting in restoration of the environment up to greenfield status. The decommissioning plan is fulfilled when the approved end state of the facility has been reached.