Spent nuclear fuel

Spent nuclear fuel is reactor fuel removed after irradiation. It contains residual uranium, plutonium, and radioactive fission products that generate heat and radiation.

Nuclear fission: A nuclear reaction in which a heavy atomic nucleus splits into smaller nuclei, releasing energy and neutrons. Fission in a reactor creates the radioactive products that remain in discharged fuel.
Nuclear fuel: Material containing fissile or fertile nuclides used to produce energy in a nuclear reactor. Spent fuel is the irradiated form of the material loaded into a reactor.
Spent fuel pool: A water-filled basin used to cool and shield recently discharged nuclear fuel. Freshly removed fuel is commonly kept underwater while decay heat and radiation are high.
Nuclear fuel cycle: The sequence of processes that supplies, uses, and manages nuclear fuel and its residues. Spent fuel is a central decision point between once-through and recycling pathways.
Fission product: An isotope produced when an atomic nucleus splits, often radioactive. These newly formed isotopes account for much of spent fuel’s early radioactivity and heat.
Uranium-235: A fissile uranium isotope that can sustain a nuclear chain reaction with thermal neutrons. Some uranium-235 remains in fuel after reactor operation.
Dry cask storage: A method of storing cooled spent nuclear fuel in sealed, shielded containers, usually with passive cooling. After sufficient pool cooling, fuel may be transferred to dry storage.
Once-through nuclear fuel cycle: A fuel strategy that uses reactor fuel once and disposes of it without recovering fissile materials. It treats spent fuel as waste rather than a source of recycled fuel.
Decay heat: Heat released by radioactive decay after a nuclear reactor stops operating. Its gradual decline governs cooling requirements after fuel leaves the reactor.
Uranium-238: The most abundant naturally occurring uranium isotope, which can capture neutrons and produce plutonium-239. Neutron capture transforms some of this abundant fuel constituent into plutonium.

Linked from 12 pages