What modifications does the fuel in a nuclear reactor undergo?
During its stay in the reactor core, nuclear fuel is subjected to high neutronic irradiation, which transforms its constitution over time. Before the fuel is loaded, three different parts can be distinguished: a) The fuel itself (UO2). b) The cladding c) Structural materials (grids, thimble tubes, etc.) All these materials undergo transformations, as indicated below: a) Fission products (F.P.) appear in the fuel (UO2), which are normally ? and ? emitters. On disintegration, they give rise to families of radioactive isotopes, some of which emerge for the first time as they do not exist in a natural state. Through neutronic capture reactions, part of the U-235 becomes U-236, and part of the U-238 is transformed into heavy elements, known as transuranics or actinides (TRU), such as plutomium, neptunium, americium and curium, characterized as ? emitters. The artificial radioactivity that the spent fuel assembly contains when it is removed from the reactor core is 800 million times the natu
