The front end of the nuclear fuel cycle

The front end of the nuclear fuel cycle starts with ore extraction in the mines and ends with the delivery of the enriched uranium to the nuclear fuel assembly producer.

From uranium extraction to yellow cake

Uranium is a metal that is pretty widespread in the earth's crust. It is found in the ores developed in open-cast mines or tunnels. A new technology called "in-situ leaching" – a process used for dissolving metals, including uranium, immediately after their mining – has become increasingly popular in recent years. Today, almost half of worldwide production comes from in-situ leaching.

In 2014, the main countries producing uranium were (in order of importance) Kazakhstan, Canada, Australia, Niger, Namibia, Russia, Uzbekistan, the USA, China and Ukraine. Global production of the uranium mines came to 56,217 tonnes in 2014. (Source: World Nuclear Association statistics)

Uranium is extracted from the mineral by means of a series of processes to produce a highly concentrated uranium known as yellow cake, a yellow powder around 75% of which is made up of uranium, or 750 kg of uranium oxide per tonne. The yellow cake will then be refined to obtain almost pure uranium in the form of triuranium octoxide (U3O8).


The front end of the fuel cycle, and the Belgian stakeholders

Did you know…

Kazakhstan (41%), Canada (16%) and Australia (9%) account for two-thirds of worldwide uranium production. McArthur River Mine in Canada (tunnels) alone represented 13% of global production in 2014.

yellow cake

Yellow cake

Synatom negotiates supply contracts for yellow cake. Each year it buys between 800 and 1,300 tonnes of this substance, averaging 1,000 tonnes per annum when Belgium's seven reactors are in service.

Synatom takes a long view, encompassing scheduled periodic reactor shutdowns and the characteristics of fuel use cycles.

Synatom also has strategic reserves at its disposal allowing it to make adjustments as a result of market fluctuations and any technical consequences arising at the nuclear power plants. Its strategic stocks dovetail nicely with the recommendations of the Euratom Supply Agency).

The natural uranium market is highly specific. The relatively low level of prices at present is not enough to make the mines profitable, meaning that some of these have been mothballed until the economic climate improves.

Did you know…

Uranium is traded as yellow cake. When we talk about the price of a tonne of uranium on the market, we are actually referring to the price of a tonne of yellow cake. In 2015, this ranged from 30 to 40 US dollars per pound.

Conversion of the yellow cake into uranium hexafluoride

The idea behind the conversion phase is to transform the yellow cake into pure uranium hexafluoride (UF6). This gas will then be compressed and cooled so that it liquefies. For transportation, it will be put in a special container where it will be cooled to become solid to then be carried to the enrichment plant.

The conversion market only has a small number of operators. Canada, France, the UK, the USA, Russia and China have this type of facility.

Synatom favours using a wide range of sources for its supplies.



Prior to enrichment, 1 kg of natural uranium consists of 990 grams of uranium 238, 7 grams of uranium 235 and almost 3 grams of uranium 234. Only uranium 235 is a fissile material but as it only accounts for 0.7% of the makeup of natural uranium, it is not present in sufficient proportions to be used in the pressurised water reactor-type nuclear power plants found in Belgium.
To feed the pressurised water nuclear reactors, a fuel containing uranium 235 as 3% to 5% of its volume is needed, since only the 235 isotope can undergo energy-releasing nuclear fission.

Nowadays, the enrichment by centrifuge technique has completely taken the place of gaseous diffusion, which consumes far too much energy. 

uranium 238st

uranium 235

uranium 234

How this works in a nutshell

Uranium 235 can be distinguished from uranium 238 through the slight difference in mass between them. This difference is also reflected in their differing levels of mobility.

The process involves turning the uranium hexafluoride – now back in gaseous state via heating (56°C) – at very high speed in a centrifuge.

The heaviest molecules, under the influence of the centrifugal force, are thrown out to the edge of the tube while the lightest (U235) migrate towards the centre and the top of the cylinder.

This step has to be repeated a lot of times to achieve the required enrichment.

As in the case of conversion, the enrichment market is dominated by four big companies:
China and Japan also have enrichment facilities.

Synatom negotiates enrichment contracts with various specialised companies and sees to the specific requirements of the nuclear operator.
It then manages the transfer of the uranium hexafluoride to the fuel assembly production plant assigned by the operator.

From this point on, the nuclear fuel is the responsibility of the reactor operator, so Electrabel.

Did you know…

The units used to measure enrichment services are separative work units (SWUs). These are also the units used as a benchmark for contracts and to work out the cost of separating a kilogram of uranium into two batches of varying isotopic concentrations, as part of the uranium enrichment process. It also serves to assess the production capacity of a plant.