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Production of MOX fuel

Cleaning rods prior to pellet insertion in the MOX plant

MELOX facility, located on the Marcoule nuclear site in Gard region of France, produces MOX fuel assemblies intended to feed light water reactors. Created from a mixture of uranium oxides and plutonium, MOX fuel enables the recycling of plutonium issuing from used fuel recovered during treatment operations executed at the AREVA La Hague recycling site.

Leading from the front

MELOX is the world leader in the production of MOX fuel, with more than 2,500 MTHM (metric tons of heavy metal) and more than 5,000 fuel assemblies produced.

The fabrication of MOX fuel

fuel fabrication scheme

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The fabrication of MOX (mixed oxides) fuel is similar to that of uranium oxide fuels. It is performed in 5 phases:

  • Mixing the powders: first, a primary mix is created, using plutonium oxide and depleted uranium oxide, and "chamotte" powders obtained from discarded pellets. Depleted uranium is added to this primary mix to obtain the exact concentration required by customers. The resulting material is called the secondary mix. Concentration of plutonium constitute of a fuel assembly (ranging from 3-12% concentration). Fuel concentrations are based on customer specifications.
  • Sintering: the secondary mixture is compacted in the form of pellets. These are fired in an oven at a high temperature for conversion into ceramic materials
  • Grinding: the pellets are ground to obtain the required pellet diameter, to the nearest micron. Pellets which do not meet the required specifications are returned for recycling into chamotte. 
  • Graining: the pellets are then inserted into zirconium alloy tubes known as “rods.” Each rod is about 4 meters long and is made up of around 320 pellets, depending on customer requirements. The rods are then carefully cleaned, and subsequently inspected.
  • Assembly: this final stage involves inserting the rods into a metal structure to form a “fuel assembly.” This assembly is the finished product for customer delivery. These assemblies are subject to manufacturing inspections to verify their future performance in the reactor.

Almost 130 quality control parameters are monitored throughout the manufacturing process.

A recycled fuel assembly provides sufficient energy to power a city of 100,000 inhabitants for one year.

EUROFAB program: “MOX for peace”–recycling military fuel

During the 1990s, the United States and the Russian Federation committed to reducing their nuclear arsenal. Both states decided to dispose of 34 metric tons each of plutonium produced for defense purposes.

In 2003, the AREVA group was chosen by the United States to produce 4 MOX fuel assemblies from American plutonium of military origin.

The production of these assemblies was carried out on 2 sites.

  • Fabrication of pellets and rods took place at the AREVA NC Cadarache facility in the fall of 2004.
  • Fuel assembly operations took place at the MELOX plant in early 2005.

The 4 assemblies produced were loaded in June 2005 into the Catawba nuclear power plant, owned by the American electrical utility company Duke Power. They have enabled the production of power sufficient to meet the electricity demands equivalent to those of a city of nearly 10,000 inhabitants a year. The American program demonstrates that civil nuclear applications, and the use of MOX in particular, can contribute to the non-proliferation of nuclear weapons.