Nuclear talks resume Wednesday between Iran and world powers after the last round stalled over issues that include Iran's planned heavy water reactor and the levels of uranium enrichment. Iran later agreed to provide U.N. nuclear inspectors with greater information and access, but it's uncertain whether the concessions will be enough to push envoys in Geneva closer to a deal. Iran seeks a rollback in U.S.-led economic sanctions, while the West is pressing it to curb its uranium enrichment — the process to make nuclear fuel. In the past decade, Iran's nuclear program has advanced on many fronts and more facilities are planned.
RAISED AT TALKS
— ARAK HEAVY WATER REACTOR: Such reactors can run on non-enriched uranium as fuel and uses a molecular variant of water as a coolant. Heavy water reactors also produce more plutonium byproducts than conventional reactors. Plutonium can be used in nuclear weapons. Iran began work on its facility in 2004 in Arak, about 250 kilometers (150 miles) southwest of Tehran. U.N. nuclear inspectors have visited the site, but have been promised wider access under the latest accord between Iran and the U.N's International Atomic Energy Agency, or IAEA. The reactor is nearing completion, but no specific date has been announced to begin operations. Iran says the reactor will be used to produce isotopes for medical and industrial uses. The country also does not possess the technology needed to reprocess the plutonium byproducts for possible use in nuclear arms.
— ENRICHMENT SITES: Iran has two main uranium enrichment facilities. The oldest and largest — in Natanz, about 260 kilometers (160 miles) southeast of Tehran — is largely built underground and is surrounded by anti-aircraft batteries. Uranium enrichment began in 2006. Another site is known as Fordo, which is built into a mountainside south of Tehran. Its construction was kept secret by Iran until it was disclosed in September 2009 in a pre-emptive move before its existence was revealed by Western intelligence agencies. The area is heavily protected by the Revolutionary Guard. U.N. nuclear inspectors have visited both sides and have installed round-the-clock monitoring systems.
— BUSHEHR: Iran's first energy-producing nuclear reactor, which began full operations in early 2013. U.N. inspectors frequently visit the site.
— TEHRAN: The main research reactor is in Iran's capital, mainly involved in producing isotopes for cancer treatment. U.N. inspectors have access to the site.
— PLANNED: Iranian officials have noted various plans for more reactors over the next 20 years, but no firm details have been released and progress is unclear. The most discussed proposal is an energy-producing reactor in Darkhovin, in the southwestern Khuzestan province, built entirely with domestic technology. Iran has pledged to give the IAEA a full accounting of its proposals.
URANIUM MINES AND PROCESSING
— SAGHAND: Iran's main uranium mine, in the central province of Yazd. It is the country's principal source of uranium ore. Iran has granted U.N. inspectors access.
— GACHIN: A smaller uranium mining site and processing facility near Bandar Abbas on the Persian Gulf. U.N. inspectors were promised access in the recent deal with the IAEA.
— ARDAKAN: A planned plant for processing uranium ore into yellowcake, a uranium concentrate that is the basic feedstock in the steps to make nuclear fuel. The plant, about 500 kilometers (300 miles) southeast of Tehran, is not yet in operation. The other site, Gachin, has produced small amounts of yellowcake since 2006.
— ISFAHAN URANIUM CONVERSION FACILITY: A plant that reprocesses yellowcake into a gas, which is then fed into centrifuges for enrichment. A separate facility in Isfahan, about 250 kilometers (150 miles) south of Tehran, produces non-enriched fuel for the planned Arak reactor.
— PLANNED: Iran claims it seeks to build 10 new uranium enrichment sites, but details and timetables have not been made clear.
PARCHIN MILITARY BASE: The base, southeast of Tehran, is a hub for Iran's conventional munitions industry. The site has also been suspected of housing a secret underground facility used for blast tests related to potential nuclear triggers. Iran denies the claim. IAEA inspectors visited the site twice in 2005, but only examined one of four areas of potential interest. The U.N. nuclear chief, Yukiya Amano, said he hopes to raise the issue of a repeat inspection in future talks with Iranian officials.