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 of 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 to greenfield status. The decommissioning plan is fulfilled when the approved end state of the facility has been reached.