Weapons-grade uranium process explained

The seven main processes involved in making enriched uranium from mined ore
Iran nuclear truck
A truck arrives at the Isfahan uranium conversion facility (UCF), central Iran. Photograph: Ehsan Khosravi/AP


2 Yellowcake When ore comes out of the ground it can be less than 1% uranium oxide. Uranium oxide is leached out of the ore with strong acids or alkaline solutions and dried to 'yellowcake', which is more than 80% uranium oxide. Iran has mastered this process.

3 Conversion Yellowcake is processed into a gas, uranium hexafluoride. Iran's conversion plant is at Isfahan.

4 Enrichment Uranium hexafluoride can be fed into centrifuges which separate out the most fissile uranium isotope U-235. Low enriched uranium for civilian reactors has a 3%-4% concentration of U-235. 'Weapons-grade' uranium is 90% enriched.


