Reprocessed uranium (RepU) is the

uranium Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weakly ...

recovered from

nuclear reprocessing Nuclear reprocessing is the chemical separation of fission products and actinides from spent nuclear fuel. Originally, reprocessing was used solely to extract plutonium for producing nuclear weapons. With commercialization of nuclear power, ...

, as done commercially in France, the UK and Japan and by nuclear weapons states' military plutonium production programs. This uranium makes up the bulk of the material separated during reprocessing. Commercial LWR

spent nuclear fuel Spent nuclear fuel, occasionally called used nuclear fuel, is nuclear fuel that has been irradiated in a nuclear reactor (usually at a nuclear power plant). It is no longer useful in sustaining a nuclear reaction in an ordinary thermal reactor an ...

contains on average (excluding cladding) only four percent

plutonium Plutonium is a radioactive chemical element with the symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhib ...

minor actinides The minor actinides are the actinide elements in used nuclear fuel other than uranium and plutonium, which are termed the major actinides. The minor actinides include neptunium (element 93), americium (element 95), curium (element 96), berkeliu ...

and

fission products Nuclear fission products are the atomic fragments left after a large atomic nucleus undergoes nuclear fission. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons, the relea ...

by weight. Despite it often containing more fissile material than

natural uranium Natural uranium (NU or Unat) refers to uranium with the same isotopic ratio as found in nature. It contains 0.711% uranium-235, 99.284% uranium-238, and a trace of uranium-234 by weight (0.0055%). Approximately 2.2% of its radioactivity comes ...

, reuse of reprocessed uranium has not been common because of low prices in the uranium market of recent decades, and because it contains undesirable isotopes of uranium. Given sufficiently high uranium prices, it is feasible for reprocessed uranium to be re- enriched and reused. A higher enrichment level is required to compensate for the ²³⁶U which is lighter than ²³⁸U and therefore concentrates in the enriched product. As enrichment concentrates lighter isotopes on the "enriched" side and heavier isotopes on the "depleted" side, will inevitably be enriched slightly stronger than , which is a negligible effect in a once through fuel cycle due to the low (55 ppm) share of in natural uranium but can become relevant after successive passes through an enrichment-burnup-reprocessing-enrichment cycle, depending on enrichment and burnup characteristics. readily absorbs

thermal neutron The neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts. The term ''temperature'' is used, since hot, thermal and cold neutrons are moderated in a medium with ...

s and converts to fissile which needs to be taken into account if it reaches significant proportions of the fuel material. If interacts with a fast neutron there is a chance of a (n,2n) "knockout" reaction. Depending on the characteristics of the reactor and

burnup In nuclear power technology, burnup (also known as fuel utilization) is a measure of how much energy is extracted from a primary nuclear fuel source. It is measured as the fraction of fuel atoms that underwent fission in %FIMA (fissions per init ...

, this can be a larger source of in spent fuel than enrichment. Also, if fast breeder reactors ever come into commercial use, reprocessed uranium, like

depleted uranium Depleted uranium (DU; also referred to in the past as Q-metal, depletalloy or D-38) is uranium with a lower content of the fissile isotope than natural uranium.: "Depleted uranium possesses only 60% of the radioactivity of natural uranium, ...

, will be usable in their breeding blankets. There have been some studies involving the use of reprocessed uranium in CANDU reactors. CANDU is designed to use natural uranium as fuel; the ²³⁵U content remaining in spent PWR/BWR fuel is typically greater than that found in natural uranium, which is about 0.72% ²³⁵U, allowing the re-enrichment step to be skipped. Fuel cycle tests also have included the DUPIC (Direct Use of spent PWR fuel In CANDU) fuel cycle, where used fuel from a Pressurized Water Reactor (PWR) is packaged into a CANDU fuel bundle with only physical reprocessing (cut into pieces) but no chemical reprocessing. Opening the cladding inevitably releases volatile fission products like

xenon Xenon is a chemical element with the symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...

tritium Tritium ( or , ) or hydrogen-3 (symbol T or H) is a rare and radioactive isotope of hydrogen with half-life about 12 years. The nucleus of tritium (t, sometimes called a ''triton'') contains one proton and two neutrons, whereas the nucleus ...

krypton-85 Krypton-85 (85Kr) is a radioisotope of krypton. Krypton-85 has a half-life of 10.756 years and a maximum decay energy of 687 keV. It decays into stable rubidium-85. Its most common decay (99.57%) is by beta particle emission with maximum ...

. Some variations of the DUPIC fuel cycle make deliberate use of this by including a voloxidation step whereby the fuel is heated to drive off semi-volatile fission products and/or subjected to one or more reduction / oxidation cycles to transform nonvolatile oxides into volatile native elements and vice versa. The direct use of recovered uranium to fuel a CANDU reactor was first demonstrated at

Qinshan Nuclear Power Plant The Qinshan Nuclear Power Plant (秦山核电站) is a multi-unit nuclear power plant in Qinshan Town, Haiyan County, in Jiaxing, Zhejiang province, China. Development The construction of the units involved three separate phases. ;Phase I: ...

in China. The first use of re-enriched uranium in a commercial LWR was in 1994 at the Cruas Nuclear Power Plant in France. In 2020 France, one of the countries with the biggest reprocessing capacity, held a stock of of reprocessed uranium, up from in 2010. Every year France processes of spent fuel into

reactor grade plutonium Reactor-grade plutonium (RGPu) is the isotopic grade of plutonium that is found in spent nuclear fuel after the uranium-235 primary fuel that a nuclear power reactor uses has burnt up. The uranium-238 from which most of the plutonium isotopes der ...

(for immediate further processing into

MOX fuel Mixed oxide fuel, commonly referred to as MOX fuel, is nuclear fuel that contains more than one oxide of fissile material, usually consisting of plutonium blended with natural uranium, reprocessed uranium, or depleted uranium. MOX fuel is an ...

) and of reprocessed uranium which is largely stockpiled. There are provisions in place for the storage of this reprocessed uranium for up to 250 years for potential future use. Given France's domestic uranium enrichment capabilities, this stockpile constitutes a strategic reserve for the case of a major disruption of uranium supply as France does not have domestic

uranium mining Uranium mining is the process of extraction of uranium ore from the ground. Over 50 thousand tons of uranium were produced in 2019. Kazakhstan, Canada, and Australia were the top three uranium producers, respectively, and together account ...

References

Further reading