What is uranium enrichment?
Here are details about the process of uranium enrichment as world
powers began talks with Iran on Monday, hoping the meeting will lead to
new negotiations over a nuclear program the West believes is for making
atomic bombs.
Western powers want Iran to suspend uranium enrichment activity,
which can produce fuel for nuclear power reactors or provide material
for bombs if refined to a higher degree.
What is enrichment?
Uranium is found naturally in a variety of forms but only a
particular adapted form of the mineral can be used to generate
electricity. File Photo |
Enrichment is a process of increasing the proportion of fissile
isotope found in uranium ore (represented by the symbol ‘U’) to make it
usable as nuclear fuel or the compressed, explosive core of nuclear
weapons.
Why uranium must be enriched?
Uranium is found naturally in a variety of forms but only a
particular adapted form of the mineral can be used to generate
electricity or create explosives.
This type, called U-235 to represent its mass, is present in only
about 0.7 percent of mined ore while most of the rest is U-238, which
has a slightly heavier mass.
To generate electricity, the concentration of U-235 must be increased
to between 3 and 5 percent. It must be refined to levels over 80 percent
to create the core of an atom bomb.
Technologies: The two most
popular production techniques require uranium ore, known as “yellow
cake”, to be converted into a gas called uranium hexafluoride (UF-6)
before enrichment.
Diffusion method:
When gaseous uranium is pumped through a porous barrier, the lighter
U-235 atoms traverse the pores at a quicker rate than U-238. This is
like smaller grains of sand passing through a sieve quicker than the
bigger ones. The process has to be repeated about 1,400 times to get
U-235 at a concentration of 3 percent of the UF-6.
Centrifuge method:
Like the diffusion process, the centrifuge method exploits the slight
difference in mass between U-235 and U-238.
Uranium gas is fed into a cylindrical centrifuge. It spins at
supersonic speeds, causing the heavier U-238 to move towards the
cylinder’s outer edge while U-235 collects around the centre.
Enriched U-235 is removed and put through the same process many times
to raise its concentration.
Around 1,500 centrifuges running non-stop for months would be needed
to make the 20 kg (45 pounds) of highly-enriched uranium needed for one
crude warhead.
According to the International Atomic Energy Agency’s last report in
November, Iran temporarily halted low-level enrichment work at Natanz in
mid-November, without giving a reason, but the number of centrifuge sets
- cascades - in operation had still increased in the last few months.
According to the report Iran started producing small batches of 20
percent enriched uranium with 164 centrifuges at Natanz in February,
fuelling Western fears that Iran aims to develop nuclear bombs.
In August, the IAEA said Iran had begun using a second cascade of
centrifuge machines to make the work more efficient. |