Nuclear reprocessing in the context of "Nuclear power station"

A nuclear power plant (NPP), also known as a nuclear power station (NPS), nuclear generating station (NGS) or atomic power station (APS) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a generator that produces electricity. As of October 2025, the International Atomic Energy Agency reported that there were 416 nuclear power reactors in operation in 31 countries around the world, and 62 nuclear power reactors under construction.

Most nuclear power plants use thermal reactors with enriched uranium in a once-through fuel cycle. Fuel is removed when the percentage of neutron absorbing atoms becomes so large that a chain reaction can no longer be sustained, typically three years. It is then cooled for several years in on-site spent fuel pools before being transferred to long-term storage. The spent fuel, though low in volume, is high-level radioactive waste. While its radioactivity decreases exponentially, it must be isolated from the biosphere for hundreds of thousands of years, though newer technologies (like fast reactors) have the potential to significantly reduce this. Because the spent fuel is still mostly fissionable material, some countries (e.g. France and Russia) reprocess their spent fuel by extracting fissile and fertile elements for fabrication into new fuel, although this process is more expensive than producing new fuel from mined uranium. All reactors breed some plutonium-239, which is found in the spent fuel, and because Pu-239 is the preferred material for nuclear weapons, reprocessing is seen as a weapon proliferation risk.

High-level waste (HLW) is a type of nuclear waste created by the irradiation of nuclear fuel in a reactor. Irradiation causes a build-up of fission products and transuranic elements (generated by capture of neutrons) in the fuel. Fission products typically have a much shorter half-life than uranium, which means the irradiated fuel is more radioactive and thus hotter than fresh fuel – high-level waste has heat output of >2 kW/m. At the same time, the fissile material (usually uranium-235) is used up, so that the fuel is no longer able to sustain the operation of the reactor and must be recycled or disposed of as waste.

High-level waste includes spent nuclear fuel itself as well as the byproducts of nuclear reprocessing, which results in liquid raffinates and other waste streams. Liquid wastes are not suitable for disposal, so these are vitrified to convert them into a solid, glass form which is suitable for disposal.

The nuclear fuel cycle, also known as the nuclear fuel chain, is the series of stages that nuclear fuel undergoes during its production, use, and recycling or disposal. It consists of steps in the front end, which are the preparation of the fuel, steps in the service period in which the fuel is used during reactor operation, and steps in the back end, which are necessary to safely manage, contain, and either reprocess or dispose of spent nuclear fuel. If spent fuel is not reprocessed, the fuel cycle is referred to as an open fuel cycle (or a once-through fuel cycle); if the spent fuel is reprocessed, it is referred to as a closed fuel cycle.

Spent fuel pools (SFP) are storage pools (or "ponds" in the United Kingdom) for spent fuel from nuclear reactors. They are typically 40 or more feet (12 m) deep, with the bottom 14 feet (4.3 m) equipped with storage racks designed to hold fuel assemblies removed from reactors. A reactor's local pool is specially designed for the reactor in which the fuel was used and is situated at the reactor site. Such pools are used for short-term cooling of the fuel rods. This allows short-lived isotopes to decay and thus reduces the ionizing radiation and decay heat emanating from the rods. The water cools the fuel and provides radiological protection from its radiation.

Pools also exist on sites remote from reactors, for longer-term storage such as the Independent Spent Fuel Storage Installation (ISFSI), located at the Morris Operation, or as a production buffer for 10 to 20 years before being sent for reprocessing or dry cask storage.

Naturally occurring iodine (₅₃I) consists of one stable isotope, I, and is a mononuclidic element for atomic weight. Radioisotopes of iodine are known from I to I.

The longest-lived of those, I, has a half-life of 16.14 million years, which is too short for it to exist as a primordial nuclide. It is, however, found in nature as a trace isotope and universally distributed, produced naturally by cosmogenic sources in the atmosphere and by natural fission of the actinides. Today, however, most is artificial as fission product; like krypton-85 the contribution of past nuclear testing and of operating reactors are dwarfed by release from nuclear reprocessing.

Chlorine trifluoride is an interhalogen compound with the formula ClF₃. It is a colorless, poisonous, corrosive, and extremely reactive gas that condenses to a pale-greenish yellow liquid, the form in which it is most often sold (pressurized at room temperature). It is notable for its extreme oxidation properties. The compound is primarily of interest in plasmaless cleaning and etching operations in the semiconductor industry, in nuclear reactor fuel processing, historically as a component in rocket fuels, and various other industrial operations owing to its corrosive nature.