Construction of core

A typical reactor core consists of around 200 Fuel Assemblies (FA), each measuring 4 m in length and weighing 750 kg.
These assemblies spend three to five years in the core and are moved at periodic intervals, to move them closer to the center as they are exhausted. Their arrangement also takes other constraints into account: alignment with the control and shutdown rods, interfaces between the different assemblies, irradiation of the pressure vessel, etc.