Each year, some of the fuel assemblies are removed from the reactor and replaced with new ones.
The spent fuel is radioactive and produces a considerable amount of heat, which must be taken into account when the spent fuel is handled and stored. While a fresh fuel assembly can safely be held by hand, a spent assembly must be handled with the help of a remote-controlled device operated from behind a radiation shield. A meter-thick concrete wall or a few meters of water constitute an adequate shield.
The spent fuel assemblies are cooled down for approximately five years in the reactor hall’s water pools. All nuclear power plants have redundant safety systems in place for fuel handling, storage, and cooling operations.