Exposure of concrete structures to neutrons and gamma radiation in nuclear power plants, and high-flux material testing reactors, can induce radiation damage to their concrete structural components. Paramagnetic defects and optical centers are easily formed, but very high fluxes are necessary to displace a sufficiently high number of atoms in the crystal lattice of the minerals present in concrete before significant mechanical damage is observed.
However, neutron irradiation with a very high neutron fluence (number of neutrons per unit of cross-section area: neutron/cm) is known to render amorphous a fraction of the quartz present in some concrete aggregates. This amorphization process is also called metamictization. Metamict quartz with its disordered lattice structure is prone to alkali–silica reaction and can thus be responsible of harmful chemical expansion in the concrete of nuclear containment structures.