Neutron-induced swelling is the increase of volume and decrease of density

Density

The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...

 of materials subjected to intense neutron radiation

Neutron radiation

Neutron radiation is a kind of ionizing radiation which consists of free neutrons. A result of nuclear fission or nuclear fusion, it consists of the release of free neutrons from atoms, and these free neutrons react with nuclei of other atoms to form new isotopes, which, in turn, may produce...

. Neutrons impacting the material's lattice rearrange its atoms, causing buildup of dislocation

Dislocation

In materials science, a dislocation is a crystallographic defect, or irregularity, within a crystal structure. The presence of dislocations strongly influences many of the properties of materials...

s, void

Void

-In science and engineering:*Void , the empty spaces between galaxy filaments*Lack of matter, or vacuum*Void, in boiling heat transfer, formed where there is a departure from nucleate boiling, causing a critical heat flux...

s, and Wigner energy. Together with the resulting strength reduction and embrittlement

Embrittlement

Embrittlement is a loss of ductility of a material, making it brittle. Various materials have different mechanisms of embrittlement.* Hydrogen embrittlement is the effect of hydrogen absorption on some metals and alloys....

, it is a major concern for materials for nuclear reactor

Nuclear reactor

A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...

s.

Materials show significant differences in their swelling resistance.

See also:

• Radiation hardening
  Radiation hardening
  Radiation hardening is a method of designing and testing electronic components and systems to make them resistant to damage or malfunctions caused by ionizing radiation , such as would be encountered in outer space, high-altitude flight, around nuclear reactors, particle accelerators, or during...