4. Neutron radiography

As neutrons interact with matter in very different ways to electromagnetic radiation, so too does their transmission (figure 5 ). In particular, neutrons easily penetrate many metal walls, and are highly sensitive to the presence of hydrogen. They can therefore be used for non-destructive testing, by direct radiography (neutronography) of large, complex devices with buried components.

Intense neutron beams transported by neutron guides far from the reactor provide background-free images. Neutronography facilities built directly onto a channel in a reactor enable gamma radiography or mixed gamma + neutron radiography to be carried out by filtering the neutrons.