x Abu Dhabi, UAESunday 23 July 2017

The life cycle of reactor uranium

Uranium's path from the ground to storage as nuclear waste is long.

1 Uranium, a natural metal said to be about 500 times more common than gold is mined. Canada and Australia hold the world's largest deposits.

2 Mined uranium ore is milled and concentrated to bring its purity up from about 0.1 per cent to 80 per cent. It is packed into 200-litre barrels that are called "yellowcake".

3 Yellowcake is made of uranium-235, the highly fissionable isotope used in atomic bombs, and uranium-238. About 0.7 per cent of natural uranium is of the 235 type, but that concentration needs to reach 3.5 to 5 per cent for a standard reactor.

4 That's where enrichment comes in, where the uranium is converted to a gas and separated into two streams, one for U-235 and one for U-238. The UAE will not enrich uranium, as part of its commitment to transparency.

5 Both uranium isotopes are pressed into pellets and baked at up to 1,400C.

6 They are then stacked into fuel rods more than 3 metres long, which together form the fuel assemblies in nuclear reactors. The Korean APR1400 model the UAE plans to use will require 141 assemblies per reactor.

7 Inside the reactor, the uranium undergoes a process called fission that releases large amounts of energy used to create steam that powers a turbine to produce electricity. One tonne of natural uranium can make about 44 million kilowatt hours of electricity, which would require about 20,000 tonnes of coal or 8.5 million cubic metres of gas.

8 After 18 months, some of the fuel assemblies are removed. The UAE plans to cool those in water for five to 20 years. Once cooled, they will be encased in concrete and stored on site.

9 Some countries send fuel to facilities where the uranium is recycled. That helps cut nuclear waste.

* Source: World Nuclear Assocation; US Nuclear Regulatory Commission