Core components normally have a longer operational life than the nuclear fuel and are only removed when the structural integrity is reduced by crack­ing, corrosion or ageing phenomena or, in the case of control rods, when their neutron absorption capacity has been reduced. The radioactivity in the core components is mainly activation products, the most important from a handling point of view being cobalt-60. From a disposal point of view there are also some long-lived nickel and niobium isotopes and the core components are generally considered to be ILW.

The radiation level from the most exposed core components is similar to or higher than from the spent nuclear fuel, but the heat generation is lower and it decays more rapidly.[85] For practical reasons the core components are initially handled in a similar way to the spent nuclear fuel and stored in the reactor spent fuel pool.