Reassessing North Korea's Nuclear Tests
August 7, 2012
In an analysis for the Bulletin of the Atomic Scientists, Frank Pabian and Siegfried Hecker provide a reassessment of North Korea's two nuclear tests, giving new estimates of the tests' locations and yields. Comparing these tests with Pakistan's 1998 nuclear test, they find "a number of similarities... between Pakistani and North Korean nuclear testing tunnel design," and speculate that a third North Korean nuclear test could involve multiple devices, as did Pakistan's first test.
Basing their analysis on their revised estimates of test locations and a Korean Central Television broadcast purporting to show the layout of the 2009 testing tunnel, Pabian and Hecker note similarities between the North Korean and Pakistani tests in both tunnel lengths and containment practices. They write that "Although the similarities we cite in some North Korean and Pakistani nuclear test practices do not constitute proof of collaboration, they give us concern that North Korea could have learned a lot from the Pakistanis."
The authors further note that the tunnel for a third test appears ready, and that it could take as little as two weeks to prepare for the test. They argue that the decision to test currently appears to rest on the North Korean government's political calculations, and discuss what a third test might entail:
North Korea has strong technical reasons to do a third plutonium test, in spite of its meager plutonium inventory, which we estimate to be 24 to 42 kilograms, to better calibrate its computer models and understand implosion devices. It is therefore conceivable that North Korea may conduct two tests simultaneously, using a double fishhook at the end of the tunnel, with one bomb fueled by HEU and a second by plutonium. Pakistani scientists made a similar decision to conduct multiple tests simultaneously to maximize technical results. If Pyongyang has more HEU than we surmise, it may do more than one HEU test with different designs. Two detonations will yield much more technical information than one, and they will be no more damaging politically than if North Korea conducted a single test.