2. The physics of fast breeder reactors

2.1 Principle of plutonium regeneration (over-, iso- or under-generation)

Fission of the nucleus of an atom, typically ²³⁹ Pu, releases energy of around 200 MeV, essentially in the form of kinetic energy carried by the fission products (FPs) within the fuel. This kinetic energy is then dissipated in thermal form by slowing down the FPs in the surrounding environment. So, to produce 1 TWh of heat, you need to fission around 44 kg of fissile material. Expressed in kg per TWh of electricity (noted TWhe), we need to take into account the electrical efficiency of the reactor-turbine assembly, which varies according to the type of nuclear reactor. For LWRs, with an efficiency of around 33%, fission is required at around 130 kg/TWhe. For RNRs...