Once a nuclear power plant has been taken off the grid, the burned-out fuel elements are still on site. In the post-operational phase, which lasts around five years, the fuel elements are removed from the plant into the intermediate on-site storage facility. At the same time, other parts of the plant, such as the cooling towers, generator transformers and turbines, and the generator in pressurised water reactors, are also dismantled.
In the reactor building itself, the dismantling of various components and the initial decontamination work are the main focus in preparing for decommissioning. It takes an estimated ten to 15 years to decommission the nuclear elements once the post-operational phase has been completed. The aim of the decommissioning process is to return it to a greenfield site, i.e. permitting the unrestricted use of the site once the power plant is gone.