United Nations nuclear inspectors have been allowed to visit the Arak reactor site in Iran for the first time since April. The site is home to a heavy water reactor that produces plutonium, an alternative to enriched uranium. Arak is the nuclear location that had been kept secret from the world until exposed by an opposition group in exile in 2002. That was the catalyst for the subsequent confrontation with the International Atomic Energy Agency. The visit by the watchdog group comes as part of an agreement between Iran and the IAEA to discuss certain outstanding nuclear issues.