Electromagnetic radiation with a wavelength shorter than 10 picometres (10 -11 m), i.e. a frequency higher than 30 exahertz (3.10 19 Hz). This type of radiation is emitted by radioactive nuclei when they undergo de-excitation. Electron-positron annihilation also produces two gamma photons. This phenomenon is exploited in medical imaging (positron emission tomography, PET). Gamma rays are detected in cosmic radiation resulting from sources in which very energetic phenomena have occurred.

Splitting of a heavy atomic nucleus into several lighter nuclei. Fission can be spontaneous (such as for mendelevium-258 or several Rutherfordium isotopes) or more frequently caused by the absorption of a neutron (such as for uranium-235 or plutonium-239). Neutrons, gamma radiation and heat are released when fission occurs.

Framework for IrraDiation Experiments. An Nuclear Energy Agency (NEA) international programme to support the JHR Material Test Reactor project by preparing joint experimental programmes in the JHR Material Test Reactor.

FUel Irradiation CApsule. This is a capsule-type experimental device designed to study the behaviour of nuclear fuels in static conditions up to the deterioration/ failure of the cladding by varying the baking time. This device will be used to test fuel ageing and deterioration, as well as to study new fuels.