Nuclear fuel fabrication is the stage of the nuclear fuel cycle in which enriched uranium hexafluoride (UF6) gas is converted into fuel for nuclear power reactors. Fabrication also can involve Mixed oxide fuel (MOX), which is a combination of uranium and plutonium components.
Light Water Reactor Low-Enriched Uranium Fuel
Fuel fabrication for light water power reactors (LWRs) typically begins with receipt of low-enriched uranium (LEU) hexafluoride (UF6) from an enrichment plant. The UF6, in solid form in containers, is heated to gaseous form, and the UF6 gas is chemically processed to form LEU uranium dioxide (UO2) powder. This powder is then pressed into pellets, sintered into ceramic form, loaded into Zircaloy tubes, and constructed into fuel assemblies. Depending on the type of light water reactor, a fuel assembly may contain up to 264 fuel rods and have dimensions of 5 to 9 inches square by about 12 feet long.
Light Water Reactor Mixed Oxide Fuel
Mixed oxide fuel (MOX) fuel differs from LEU fuel in that the dioxide powder from which the fuel pellets are pressed is a combination of UO2 and plutonium oxide (PuO2). The U.S. Nuclear Regulatory Commission (NRC) was directed by Congress to regulate the Department of Energy's (DOE's) fabrication of MOX fuel used for disposal of plutonium from international nuclear disarmament agreements.
Nonpower Reactor Fuel
Nonpower reactors are much smaller reactors that do not generate electrical power but are used for research, testing, and training. Nonpower reactors can include research reactors and reactors used to produce irradiated target materials. The fuel design varies with the reactor type and manufacturer. Plate-type fuel consists of several thin plates containing a uranium mixture clad with aluminum. Another fuel is in the shape of rods and consists of a uranium and zirconium/hydride mixture. There are also compact, self-contained, low-power (less than 5 watts) tank-type reactors.
Safety Concerns at Fabrication Plants
Chemical, radiological, and criticality hazards at fuel fabrication facilities are similar to hazards at enrichment plants. The primary hazards include the chemical and radiological hazard of a UF6 release and the potential for mishandling the enriched uranium, which could create a criticality accident (inadvertent nuclear chain reaction). Most at risk from these hazards are the plant workers. These facilities generally pose a low risk to the public.
Disclaimer: This article is taken wholly from, or contains information that was originally published by, the U.S. Nuclear Regulatory Commission. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the U.S. Nuclear Regulatory Commission should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.