As announced, Iran has increased its level of uranium enrichment since July 7. It has gone from 3.57% to 4.5%, thus exceeding the limits agreed not to exceed in 2015, so that the signed document remains breached. It is far from the 20% that was already operating years ago, but the Tehran government has already threatened to restart the sealed centrifuges and reach the previous purity limits. Of course, they remain far from the 90% necessary to manufacture an atomic bomb.
The reason that lead them to increase this percentage is that they were not covering the expected benefits. With this minimal increase, the spokesman for the Iranian Atomic Energy Organization, Behruz Kamalvandi, explains that they achieve “the level of purity sufficient to meet the needs of their power plants . ” Specifically the Bushehr plant, which is the only commercial reactor in use since 2013. With the double confirmation by the International Atomic Energy Agency that the signed limits have been exceeded, we now wonder what this enrichment entails.
Uranium has 92 protons and 92 electrons. Its most notable isotopes are uranium-238 (with 146 neutrons) and uranium-235 (with 143 neutrons). The first of these is the most common on Earth and represents 99.3% of any sample of natural uranium, but dense clusters of uranium-238 do not have to initiate nuclear chain reactions. But the second isotope, uranium-235, does manage to trigger those reactions. The nuclei of the uranium atoms divide into smaller nuclei and release neutrons, which allow other nuclei to divide by releasing more, thus generating a self-sustaining chain that emits huge amounts of energy.
Uranium enrichment is then the process by which this metal is subjected to obtain the u-235 isotope. If the natural proportion is 0.7%, Iran has decided in this case to reach 4.5%. But it is still a very low level to be alarmed. Does breaking this threshold imply that it is closer to creating nuclear weapons? The answer is no. The so-called “weapons grade” would have to exceed 90% and is a great technical challenge. It requires the construction and operation of very advanced centrifuges that help separate heavy and light materials and allow the U-235 to be extracted in large proportions. With this we do not say that Iran is not able to do it, only that it requires an enormous effort of energy and personnel, and it would have to multiply its production in 20 times of what it does now.
So for the moment, there is no reason to be alarmed.