North Korean nuclear reactor appears to be operational

SEOUL, Dec 22 (Reuters): A second reactor at North Korea's Yongbyon nuclear facility appears to be operational, according to the UN atomic agency.
Yongbyon is North Korea's main nuclear complex and home to its first nuclear reactor, with a five megawatt capacity, and has been the only known source of plutonium for its weapons program.
A second one - a light-water reactor - now also appears to be operational, based on observations that warm water is being discharged from it, the International Atomic Energy Agency said in a statement released late on Thursday.
"The discharge of warm water is indicative the reactor has reached criticality," IAEA Director General Rafael Mariano Grossi said in a statement.