Waste and recoverable materials
When it leaves the reactor under normal operating conditions, a fuel assembly is made up of four components: 1) Uranium, which can be recycled in fresh fuel; 2) Plutonium, which has very high energy potential; 3) Fission products (FP), which are pure waste; 4) Minor actinides other than plutonium, which are currently considered as waste. During the first few decades, the very high levels of radioactivity resulting from irradiation are due to fission products, and later to plutonium.