Neutron embrittlement

When neutrons hit components in the reactor core and change their material properties so that they can become more susceptible to so-called brittle fracture, this is called neutron embrittlement.

In order to check the embrittlement of the reactor pressure vessel, it is common international practice to install samples of the materials of the vessel in the vicinity of the reactor core already during assembly and to irradiate them there. The samples are withdrawn and tested after a certain time. Since the neutron radiation is stronger in the vicinity of the reactor core than in the vessel, the samples taken allow conclusions to be made about the future behaviour of the reactor pressure vessel material.