Nuclear fuel cycle Wikipedia
The nuclear fuel cycle, The buildup of fission products and consumption of fissile isotopes eventually stop the nuclear reaction, causing the fuel to become a spent nuclear fuel. When 3% enriched LEU fuel is used, the spent fuel typically consists of roughly 1% U235, 95% U238, 1% plutonium and 3% fission products. Spent fuel and other highlevel radioactive waste is extremely hazardous