The safe enclosure of the radioactive inventory of a nuclear plant is structured according to the multiple barrier principle, i.e. radioactive substancesRadioactive substances within the meaning of the Atomic Ener... must pass these multiple different barriers connected in series before they are released. Barriers of a nuclear reactorSee 'reactor'.:
- Retention of the fission productsNuclides generated by fission or subsequent radioactive deca... in the nuclear fuelIn accordance with the definition of the German Atomic Energ... itself,
- Enclosure of the nuclear fuelIn accordance with the definition of the German Atomic Energ... in claddingTightly bound (usually metallic) casing directly surrounding... tubes,
- Enclosure of the fuelSee 'nuclear fuel'. elements in the reactor pressure vesselThick-walled cylindrical steel vessel enclosing the reactor ... and primary coolantAny substance used to remove the heat in a nuclear reactor. ... system,
- Gas-tight containmentGastight case around a reactor and the circuit and auxiliary... around the reactor pressure vesselThick-walled cylindrical steel vessel enclosing the reactor ....