Nuclear decommissioning is the dismantling and decontamination of an old nuclear activity: power plant, laboratory or industrial nuclear site that no longer requires measures for radiation protection. The characteristic difference between the dismantling of other power plants is the presence of radioactive material that requires special precautions.
Generally speaking, nuclear buildings were designed for a life span of about 30–40 years. Once they come to the end of their operating life, these plants must be decontaminated to remove every radioactive contaminant. The main goal is to remove as much of the contaminated materials as possible, in order to give back a safe area to the public sector.
Decommissioning involves many administrative and technical actions. It includes clean-up of radioactivity and progressive demolition of the plant. Once a facility is decommissioned, there should no longer be any danger of a radioactive accident or any dangers to those visiting it. After a facility has been completely decommissioned, it is then released from regulatory control, and the licensee of the plant will no longer be responsible for its nuclear safety.
As a minimum, the floor, walls, and external structural surfaces within work areas should be cleaned of loose contamination. It's a slow, expensive and essential process taking place in stages due to the radioactivity in the reactor structure. A decontamination program may also require a facility capable of treating secondary waste from decontamination. The concentrated waste, representing a more significant radiation source, must be shipped for disposal in licensed disposal facilities.