1. Fuel roles

Nuclear fuel is the material containing the atoms or nuclides whose consumption by fission in a reactor releases energy. The term "fuel element" or, more simply, "fuel" refers to the product containing fissile materials, which supplies energy to a reactor core by sustaining a chain reaction.

The fuel element thus consists of :

• the material containing the fissile atoms ;

• its envelope, mainly the sheath;

• structures.

The fuel is the active part of a reactor; it is within the fuel that the fission of certain nuclei takes place, in particular uranium 235 or plutonium 239, and therefore the release of energy (around 200 MeV) associated with each of these fissions.

The configuration of the fuel...