SEOUL • North Korea runs an effectively self-sufficient nuclear programme that produces up to 150kg of highly enriched uranium a year, enough to produce around six nuclear bombs a year, according to new assessments by weapons experts.
And with an estimated plutonium stockpile of 32kg to 54kg, the reclusive state will have sufficient fissile material for about 20 bombs by the end of this year, said Dr Siegfried Hecker, a leading expert on North Korea's nuclear programme, who toured its main Yongbyon nuclear facility in 2010.
The country's true nuclear capability is impossible to verify, but after Pyongyang conducted its fifth and most powerful nuclear test last week and, according to South Korea, is preparing for another, it appears to have no shortage of mate- rial to test with.
North Korea has an abundance of uranium reserves and has been working covertly for well over a decade on a project to enrich the material to weapons-grade level, the experts say.
That project, believed to have been expanded significantly, is likely the source of up to 150kg of highly enriched uranium a year, enough for roughly six nuclear bombs, Dr Hecker wrote in a report published on Monday on the 38 North website of the US-Korea Institute at Johns Hopkins University in Washington.
Dr Jeffrey Lewis of the Middlebury Institute of International Studies said North Korea had an unconstrained source of fissile material, both plutonium from the Yongbyon reactor and highly enriched uranium from at least one and probably two sites.
"The primary constraint on its programme is gone," he said.
Weapons-grade plutonium has to be extracted from spent fuel taken out of reactors and then repro- cessed, and therefore would be limited in quantity. A uranium enrichment programme greatly boosts production of material for wea- pons.
Despite United Nations sanctions, North Korea is probably largely self-sufficient in operating its nuclear programme, although it may still struggle to produce some material and items, Dr Lewis said.
"While we saw this work in Iran, over time countries can adjust to sanctions," he said, referring to sanctions against Iran for its nu- clear programme.