The time it takes to enrich uranium depends on the level of enrichment and the technology used. For instance, producing weapons-grade uranium (around 90% U-235) from natural uranium can take from several weeks to a few months, depending on the number and type of centrifuges in operation. Iran's estimated "breakout time" to produce enough uranium for one nuclear weapon is about one to two months with its current centrifuge capabilities. However, once uranium is enriched to about 20%-60%, only a small additional effort is needed to reach weapons-grade levels, significantly shortening the final enrichment phase. The enrichment process typically involves continuous centrifuge operation and can be influenced by technical and operational factors.
More specifically, Iran's current production capacity at its main enrichment facilities could theoretically produce enough 90% enriched uranium for five weapons in about one week or for eight weapons in less than two weeks, if it uses all centrifuge capacity continuously. This process assumes uranium stockpiles already enriched to 60%, which constitute most of the work toward weapons-grade material.
For civilian reactor fuel enrichment, which is typically to low levels around 3-5% U-235, enrichment is a slower but steady process depending on plant capacity measured in separative work units (SWU). Modern centrifuge plants are more efficient than older gaseous diffusion plants, requiring less energy and time per unit of uranium enriched.
