When most people hear the word uranium, they think of mushroom clouds, Cold War standoffs or the glowing green rods from science fiction. But uranium isn’t just fuel for apocalyptic fears. It’s also a surprisingly common element that plays a crucial role in modern energy, medicine and geopolitics.
Uranium reentered the global spotlight in June 2025, when the U.S. launched military strikes on sites in Iran believed to be housing highly enriched uranium, a move that reignited urgent conversations around nuclear proliferation. Many headlines have mentioned Iran’s 60% enrichment of uranium, but what does that really mean?
As a biochemist, I’m interested in demystifying this often misunderstood element.
What is uranium?
Uranium holds the 92nd position on the periodic table, and it is a radioactive, metallic element. Radioactivity is a natural process where some atoms – like uranium, thorium and radium – break down on their own, releasing energy.
The German chemist Martin Heinrich Klaproth initially identified uranium in 1789, and he named it after the newly discovered planet Uranus. However, its power was not unlocked until the 20th century, when scientists discovered that uranium atoms could split via a process known as nuclear fission. In fission, the nucleus of the atom splits into two or more nuclei, which releases large amounts of energy.
Uranium is found almost everywhere. It is in rocks, soil and water. There are even traces of uranium in plants and animals – albeit tiny amounts. Most of it is found in the Earth’s crust, where it is mined and concentrated to increase the amount of its most useful radioactive form, uranium-235.
The enrichment dilemma
Uranium-235 is an isotope of uranium, which is a version of an element that has the same basic identity but weighs a little more or less. Think about apples from the same tree. Some are big and some are small, but they are all apples – even though they have slightly different weights. Basically, an isotope is the same element but with a different mass.
Unprocessed uranium is mostly uranium-238. It only contains approximately 0.7% uranium-235, the isotope that allows the most nuclear fission to occur. So, the enrichment process concentrates uranium-235.
Enrichment can make uranium more useful for the development of nuclear weapons, since natural uranium doesn’t have enough uranium-235 to work well in reactors or weapons. The process usually contains three steps.
Centrifuges spin the uranium to separate out its isotopes.
The first step is to convert the uranium into a gas, called uranium hexafluoride. In the second step, the gas gets funneled into a machine called a centrifuge that spins very fast. Because uranium-235 is a little lighter than uranium-238, it moves outward more slowly when spun, and the two isotopes separate.
It’s sort of like how a salad spinner separates water from…
