1. Fuel functional characteristics

1.1 Situation in the heart

A distinction must be made between EPRs and BWRs.

• In a BWR, the fuel assembly consists of a bundle of fuel rods enclosed in a casing; reactor physics dictates a zoning of rods of different fissile content ( ²³⁵ U enrichment or plutonium content) and the use of consumable poisons, usually gadolinium in the form of Gd ₂ O ₃ in UO ₂ rods. A MOX BWR assembly contains MOX rods and UO ₂ rods. Most existing boiling reactors can accommodate up to 50% or 60% MOX assemblies without modification;...