One reason why many people distrust nuclear power is because they believe it is impossible to separate civil reactors from weapons-grade fissile material.
The U.S. and its allies are seeking to gain Iran's willingness to suspend its production of near weapons-grade nuclear material at its uranium-enrichment sites in return for economic incentives.
While most are enriching below 20 percent, this material, too could be turned into weapons-grade uranium, although with greater effort than is the case for the 20-percent stockpile.