Nuclear Fuel

Just Like coal, natural gas and oil, uranium which is called a Nuclear Fuel must be processed.

Preparing uranium for using it in a reactor, it goes through a number of steps that are described below.

Uranium spent three years in the nuclear reactor for producing electricity.


1. Mining and milling

Nuclear Fuel is mined by surface or underground mining technologies.

After mining the uranium ore is transferred to a mill. There this ore is grinded to a make fine mix that is kept in sulfuric acid to for derivation of uranium. Some mines in United States of America and Kazakhstan, make use of in situ leaching (ISL) to derive the uranium from its ore.

U308 is the product of uranium which is then sold.


2. Conversion

Uranium needs to be converted in the gas form, before enriching, so U308 is transformed into gas uranium hexafluoride (UF6) at conversion place.


3. Enrichment

The majority of nuclear reactors in operation need ‘enriched’ Nuclear Fuel in the ratio of the U-235 isotope that should be raised from the level of 0.7% to 3.6 % to 5.2%. This removes around 84% of the U-238 by extracting gaseous hexafluoride of uranium into two segments.

A little amount of U-235 remains after this, this is used in metal form for yacht keels, counterweights and as a shield for radiation.

Nowadays enriching is done by centrifugal force. Research is in progress for laser enrichment.

Some reactors don’t need Nuclear Fuel enrichment.


4. Fuel fabrication

Enriched UF6 is sent to a fuel transformation plant where it is changed to pellets of uranium dioxide (UO2). These are then put in slim tubes, generally of zirconium alloy or steel, for creating fuel rods.

Around 27 tonnes of fuel is needed every year for a 1000 MWe reactor.


5. The Nuclear Reactor

These fuel rods are then used to create a core for reactor. In a reactor U-235 isotope splits creating heat, which is called a chain reaction.

U-238 in the core is changed to plutonium and its half amount used for producing one third of reactor’s output.

In traditional electricity generating plants, the heat is for producing steam to drive a turbine and an electric generator.

To preserve efficient reactor output, about one-third of the exhausted fuel is detached every year.


6. Used fuel storage

Used fuel is removed from the reactor and kept in ponds to decrease their heat and radioactivity.

This can be stored in these ponds safely. They can also be stored in a dry cool place designed by engineers to cool them.

There are two options for used fuel:

  • They can be reprocessed for reuse
  • Or just a disposal according to the norms.


7. Reprocessing 

Used uranium still has almost 95 percent of usable Nuclear Fuel.

In reprocessing the uranium and plutonium is separated by cutting the rods and dissolving them in an acidic solution.

The remaining portion of used fuel can be kept stored in liquid form, and can be later solidified as per usage.

Reprocessing is done in Europe and Russian by more than 40 years.


8. Vitrification

Just after reprocessing the liquid waste is heated to produce a dry powder which is then sealed, this sealed waste in put in steel containers, and stored with appropriate shielding.

This is the whole story of the Nuclear Fuel cycle.


9. Final disposal

The final waste which is sealed in steel containers, but still no suitable way is there for the disposal of radioactive waste; the first permanent way of disposal is expected to emerge about 2020.

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