

N.K.’s uranium bomb test would raise stakes

kh close


Published : 2013-02-05 20:37
Updated : 2013-02-05 20:37


The last two tests are believed to have been of plutonium devices, but the next logical step for Pyongyang’s ambitious nuclear program could be to conduct a highly enriched uranium explosion. That would be a major accomplishment for North Korea ― and a worrying development that would raise already high stakes for the United States and its allies.

Here’s why:




“A uranium test would be a big deal because a centrifuge plant is much easier to conceal than a plutonium reactor, which is practically impossible to hide,” said Daniel Pinkston, a Seoul-based expert on North Korea with the International Crisis Group think tank.


“While a plutonium bomb requires the assembly of a complicated weapons system to deal with pre-detonation issues, a HEU bomb is relatively easy to construct,” Harvard physicist Hui Zhang wrote in an analysis for the Bulletin of the Atomic Scientists. “Moreover, unlike plutonium, HEU poses no significant health hazards during the construction phase because of its low level of radiation.”


“Switching to HEU at this point actually increases the technical challenge” for North Korean scientists to build miniaturized nuclear warheads, James Acton, a physicist at the Carnegie Endowment for International Peace, said in an email.


Easy to dig up: North Korea says the program is for peaceful, energy-generating purposes. But while uranium enriched to low levels is used in power reactors, centrifuges can also be made to enrich uranium to the high levels needed for bombs.

North Korea apparently decided a few years ago to focus on highly enriched uranium rather than plutonium, Acton said. That’s probably because its leaders realized that “with a given amount of investment, it could produce more bombs-worth of HEU than plutonium,” he said.


Hecker estimated that Pyongyang has only 24 to 42 kilograms of plutonium ― enough for perhaps four to eight rudimentary bombs similar to the plutonium weapon used on Nagasaki in World War II. It does not appear to making more; its plutonium reactor north of Pyongyang was shut down during disarmament negotiations.

“It’s only logical that it would now test an HEU device, since that would be most helpful for designing its future arsenal,” Acton said, though he didn’t exclude the possibility of a plutonium test.



Outsiders have long raised suspicions of such a program.





Pyongyang’s long pursuit of uranium “is the clearest indication that North Korea intends to retain and enhance its nuclear weapons capabilities and has no intention to give up these capabilities,” according to Jonathan Pollack, a North Korea analyst at the Brookings Institution think tank in Washington. “That is the fundamental fact that all outside powers must address.”