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Backgrounder on Mixed Oxide Fuel

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Mixed Oxide Fuel

With the end of the Cold War, the United States and the former Soviet Union began dismantling thousands of nuclear weapons. This work resulted in large amounts of excess weapons-usable uranium and plutonium. Proper controls are needed to ensure these materials are safeguarded and managed in a way that protects the environment, health and safety.

One of the challenges is how to make sure this material will not be accessed and used in weapons in the future. In 2000, the United States and Russia signed an agreement committing each country to dispose of 34 metric tons of surplus plutonium. In 2002, the Department of Energy (DOE) proposed irradiating the plutonium, or mixing it with uranium to make mixed oxide (MOX) fuel to power existing U.S. commercial nuclear reactors. Burning MOX fuel in a reactor makes using the plutonium for any other purposes difficult. Once taken out of a reactor, the MOX fuel would not be reprocessed or reused.

MOX fuel has been fabricated for many years in Europe, and is currently produced in the United Kingdom and France. Commercial MOX-fueled light water reactors are used in France, the U.K., Germany, Switzerland and Belgium. In the U.S., MOX fuel was fabricated and used in several commercial reactors in the 1970s.

MOX Fuel Fabrication Facility

In 1998, Congress gave the NRC authority to regulate the MOX fuel fabrication facility. The NRC would evaluate both safety and environmental impacts, and perform inspections during construction and operation. The operator had to get NRC approval to begin construction and an NRC license to begin operations.

DOE signed a contract with Duke, Cogema and Stone & Webster (DCS) in 1999 to design, construct and operate the facility at the Savannah River Site near Aiken, S.C., and shut it down when plutonium disposition was completed. DCS submitted an environmental report to NRC in December 2000. The construction application followed in February 2001.

The NRC held several public meetings during its environmental review. Some of the areas covered included: health and safety, waste management, transportation, handling of hazardous materials, background radiation, water and earth resources, air quality, land use, noise, ecological resources, socioeconomic issues, and natural disasters. In January 2005, the NRC issued a final Environmental Impact Statement.

The NRC also held meetings and took comments on several drafts before authorizing construction and publishing a final Safety Evaluation Report in March 2005. NRC reviewed:

  • General information about the applicant and the plant site;
  • The applicant's financial qualifications to construct and operate the facility;
  • Provisions to protect workers and the public from radiation exposure, chemical exposure, fires, and other emergencies;
  • Plans to protect against theft, loss or diversion of special nuclear material; and
  • Management and administrative procedures.

DCS applied in 2006 to possess and use plutonium at the facility. The NRC's review is documented in a 2010 final Safety Evaluation Report. The NRC would only issue an operating license after verifying that all the major structures, systems and components have been properly constructed.

Construction began in 2007, but DOE has proposed halting construction due to the project's cost.

MOX Use in U.S. Reactors

As regulator of commercial nuclear power plants, the NRC must review and approve license amendments to allow the use of MOX fuel. DOE proposed burning the MOX fuel in two commercial reactors – Catawba and McGuire.

Fuel for nuclear power plants in the U.S. is made of low-enriched uranium. Normal reactor operations generate plutonium in that fuel. Some of the plutonium is then burned in the reactor. MOX fuel would contain 5 percent plutonium.

The NRC issued a license amendment in March 2005 to Duke Power to test four MOX fuel assemblies at its Catawba plant in South Carolina.  The assemblies were manufactured in France using U.S. weapons-grade plutonium. The NRC also approved revisions to Duke's physical security plan and additional protective measures to provide enhanced security of the MOX assemblies.

In April 2005, the MOX fuel was delivered from France to DOE, then shipped safely to the plant. Duke introduced the MOX into its Catawba reactor in late spring 2005.

Additional information on MOX can be found on the NRC's website.

April 2014

Page Last Reviewed/Updated Friday, December 12, 2014