Last week, Israel attacked three of Iran’s major nuclear facilities – Natanz, Isfahan and Fordow – killing several Iranian nuclear scientists. The facilities are strongly fortified and mostly underground, and there are contradictory reports on the extent of damage.
Natanz and Fordow are the Iranian uranium enrichment sites, while Isfahan provides raw materials. Therefore, any damage to these facilities limits the country’s ability to produce nuclear weapons.
But after all, what is exactly the uranium enrichment and why is it a cause for concern?
To understand what “enrich” uranium means, it is necessary to know a little about Uranium isotopes and on the division of the atom in a nuclear fission reaction.
What is an isotope?
All subject is made up of atoms, which in turn are made up of protons, neutrons and electrons. The number of protons determines the chemical properties of atoms, distinguishing the different chemical elements.
Atoms have the same number of protons and electrons. For example, uranium has 92 protons, while carbon has six. However, the same element may have different neutrons numbers, forming variants called isotopes.
This difference little affects chemical reactions, but it may have a huge impact on nuclear reactions.
The difference between uranium-238 and uranium-235
When we extract underground uranium, about 99.27% is uranium-238, with 92 protons and 146 neutrons. Only 0.72% is uranium-235, with 92 protons and 143 neutrons (the remaining 0.01% are other isotopes).
For nuclear reactors or nuclear weapons, these proportions must be changed. This is because, of the two main isotopes of uraniumonly uranium-235 can sustain a reaction in chain of fission: A neutrão causes the fission of an atom, releasing energy and more neutrons, which generates more physics, and so on.
This chain reaction releases a huge amount of energy. In a nuclear weapon, the goal is for this reaction to occur in fractions of second, producing a nuclear explosion.
In a civil nuclear center, the reaction is controlled. At the moment, Nuclear power plants produce about 9% of world electricity. Another vital use of civil nuclear reactions is the production of isotopes used in nuclear medicine for diagnosis and treatment of various diseases.
What is, then, the enrichment of uranium?
“Enriching” uranium means taking the element as found in nature and increasing the proportion of uranium-235, while removing uranium-238.
There are several ways to do so, but commercially enrichment is done with centrifugators. This is also the method used at Iran’s facilities.
Centrifuges take advantage of the fact that Urânio-238 is about 1% heavier than uranium-235. Uranium (in gas form) is placed on rotors that run at 50,000 to 70,000 revs per minute, with the centrifugal walls moving at speeds of 400 to 500 meters per second.
It works similar to a salad colander: Water (heavier) is thrown to the sides, while the leaves are in the center. Uranium-238, being heavier, moves to the ends of the centrifugal, leaving uranium-235 in the center.
This process is not very efficient, so it is repeated several times until the desired percentage of uranium-235 is reached.
Most civil nuclear reactors use “little enriched uranium”, with content between 3% and 5% uranium-235. This amount is sufficient to support a chain reaction and produce electricity.
What level of enrichment is necessary for nuclear weapons?
To cause an explosive chain reaction, the Uranium-235 has to thisr much more concentrated than in civil applications such as energy production or medicine.
Technically, a nuclear weapon can be done with uranium enriched at only 20% (known as “highly enriched uranium”), but Qgreater the degree of enrichment, smaller and light can be the weapon. Countries with nuclear weapons usually use uranium enriched to about 90%, known as the “arms degree”.
According to the International Atomic Energy Agency (AIEA), Iran has already enriched large amounts of uranium up to 60%. In fact, it is easier to go from 60% to 90% than from natural value to 60%, because there are less and less uranium-238 to remove.
This is why Iran is considered at risk of producing nuclear weapons and because centrifugal technology is kept under secret.
In the background, The same centrifugal technology that produces fuel for civil reactors can be used to manufacture nuclear weapons.
AIE inspectors monitor nuclear facilities worldwide to ensure that countries comply with the rules of the non -nuclear non -proliferation treaty. Although Iran will claim that it only enriches uranium for “peaceful purposes,” last week the AIEA Council considered that Iran was violating its obligations to the treaty.
