Estimates of North Korea’s Possible Nuclear Stockpile

North Korea’s state controlled media claimed on May 11 the country had completed removal of 8,000 fuel rods from its 5 megawatt plutonium production reactor at Yongbyon. Estimates by the Institute for Science and International Security suggest the fuel elements contain between 12 and 19 kilograms of plutonium. These fuel elements will have to cool for an unknown period of time in the fuel storage pond located next to the reactor building. It is estimated that within 2-3 months, the fuel could be processed and the weapon-usable plutonium made ready for production of nuclear weapons. There is no conclusive evidence that North Korea possesses any nuclear weapons, but U.S. officials assume they have produced an unknown number of nuclear devices.

The chart below provides a summary of North Korea’s estimated plutonium holdings. The three sections of the chart refer to the three distinct times North Korea is thought to have produced and recovered plutonium from the reactor at Yongbyon. It is not known how many kilograms of plutonium North Korea would require for each nuclear weapon (different designs require different amounts of material). The U.S. Department of Energy has revealed that a nuclear weapon can be produced with as little as four kilograms of plutonium. The International Atomic Energy Agency estimates that 8 kilograms are required to produce a nuclear device. We assume that North Korean weapons, if they indeed exist, require at least 5 kilograms of plutonium, yielding a possible North Korean capability of 8-11 weapons.