The shutdown and permanent removal from service of nuclear installations such as reactors and reprocessing plants at the end of their commercial life. There are several stages to taking such an installation permanently out of service. Mothballing involves shutdown and washout to attain a low level of residual radioactivity. The plant may be re-opened at a later date. Removal of nuclear material, decontamination and sealing equipment, dismantling and removing process and ancillary equipment leaves the facility inoperable. The final stage involves removal of major plant such as the reactor, demolishing the buildings, and returning to a green-field site.