Plutonium can be used in nuclear weapons production, but separating it from the reactor byproducts requires a special technology that Iran does not currently possess.
The new accord also calls on Iran to provide more details on its nuclear program including proposed new reactor sites and all planned research reactors.
This is important because such facilities use 20 percent enriched uranium, which is the highest level acknowledged by Iran and a key aspect of the ongoing nuclear talks.
Halting the 20 percent enrichment—which is several steps away from weapons-grade—is a key goal of Western envoys, for which they may offer Iran a possible easing of U.S.-led sanctions.