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Conversion services for natural uranium

Technician near a flame reactor in a plant for conversion of UF4 into UF6

The principal activity of the Chemistry Business Unit is to provide conversion services for natural uranium as uranium hexafluoride (UF6). This intermediate chemical component is then sent to the Georges Besse II plant in Tricastin, France, where it is enriched. Today, all the enrichment processes for uranium function through the use of UF6 as the chemical form of uranium.

From natural uranium to uranium hexafluoride (UF6)

The uranium extracted from mines, concentrated in the form of "yellow cake" and already under the ownership of the electricity customer, cannot be used in this state in nuclear reactors of electricity production. To be used as a fuel, it must be transformed.

The conversion operations consist of transforming the concentrated ores into uranium hexafluoride (UF6), giving it the purity needed for the fabrication of nuclear fuel.

These operations represent an essential stage in the fuel cycle between mining activities and enrichment of the uranium. 

A 2-stage process

The conversion of uranium concentrate obtained from mines is carried out through a process of chemical transformation in 2 stages:    

Transformation of natural uranium into uranium tetrafluoride

 During the first phase, the uranium is transformed into uranium tetrafluoride (UF4).

The concentrated ore is dissolved by acid, then purified to yield. After precipitation and calcination, uranium trioxide powder (UO3) is obtained, and is then hydrofluorated using hydrofluoric acid.

It is thus transformed into a green substance with a granular appearance called uranium tetrafluoride (UF4).

These operations are carried out in the COMURHEX-Malvési plant in Narbonne, France.     

Transformation of uranium tetrafluoride into uranium hexafluoride

The UF4 is then converted in a second phase of fluorination into uranium hexafluoride (UF6), using fluorine obtained by electrolysis of hydrofluoric acid.

The UF6 is made by contact of gaseous fluorine with the UF4 powder. The chemical reaction makes very high-temperature in a reactor with flames.

A last stage consists in transforming the obtained UF6 of the solid state to the gaseous state. Thus, it's possible to enrich it. These operations are carried out in the COMURHEX plant in Tricastin.

Transformation of uranium tetrafluoride into uranium hexafluoride
video

COMURHEX II: meeting tomorrow’s challenges

AREVA will be building two new uranium conversion unites on the sites of Tricastin and Malvési. Called on to replace the existing installations, they will allow the group to increase its production and to respond to market developments. 3D tour and view of the project.

COMURHEX II: New conversion plants

The demand for nuclear fuel will increase sharply over the coming years, causing an increase in the need for uranium and consequently in conversion activity.

To meet the growing needs of its customers, in 2007 AREVA decided to renovate and modernize its industrial conversion facilities at the Tricastin and Malvési plants, a project known as COMURHEX II. These future industrial installations bring together the latest advances and innovations from the research and development projects of the AREVA group.

The progressive commissioning of the units is scheduled from 2013 to 2015.