Uranium ore is extracted from either open-cast pits or by underground mining. Iran received 10 years’ worth of fuel for its civilian reactor from Russia but also mines its own. Iran could, in theory, enrich enough weapons-grade uranium to fuel a nuclear bomb within two months. Turning that uranium into a bomb core would take an additional one to 10 months. Nuclear reactors use the heat of nuclear fission from uranium fuel rods to turn water into steam to drive turbines, which then create electricity. In a nuclear power plant, uranium atoms are split in a slow, heat- producing chain reaction. Iran’s only power reactor runs on ura-nium enriched to about 3.5 percent U-235. The quick, violent chain reaction needed by a nuclear weapon re-quires the uranium to be highly enriched, usually to about 90 percent U-235. Here is how the process works MINING REFINING ENRICHMENT NUCLEAR POWER NUCLEAR WEAPONRY Diverted outputInspectors notice that a plant’s output is less than would be expected. Secret activity Surveillance reveals suspicious constructionor other work atundeclared sites. Illicit procurement Intelligence reveals illegal acquisitionof nuclearequipment. The type of bomb that watch groups think Iran would most likely try to create would require 16 kilo-grams of weapons-grade uranium and could carry a destructive force at least as great as the bomb that was dropped on Hiroshima. Signs a country may be making nuclear weapons Uranium ore is ground into a powder called yellowcake at a mill, then turned into a gaseous form to be enriched. Centrifuges refine uranium hexafluoride gas by spinning at high speeds, increasing the concentration of atoms that can be used for nuclear fission (U-235 isotope). Iran has about 10,000 centrifuges producing uranium for reactors. If it reconfigured these to make highly enriched uranium for bombs, United Nations inspectors would quickly detect it.

SOURCE: The Wisconsin Project on Nuclear Arms Control's IranWatch.org; International Atomic Energy Agency; Institute for Science and International Security. GRAPHIC: The Washington Post. Published Feb. 26, 2015.