During reactor operation, components can become radioactive (activation) or contaminated with radioactive substances (contamination).
For example, the reactor pressure vessel and its internals and the biological shield (protective concrete wall) are activated by neutron radiation during reactor operation and have to be disposed of as low- and intermediate-level waste after the decommissioning of the nuclear power plant. Components that are contaminated with radioactive substances either have to be cleaned (decontaminated) or disposed of as waste.
The Niederaichbach power plant in Bavaria (Germany) during dismantling. The reactor has already been removed. Depending on their activation, the surrounding installations will also have to be disposed of as radioactive materials.
(Image: Karlsruhe Research Center)