6 November 2017

North Korean nuclear test shows steady advance: interview with Siegfried Hecker

ELISABETH EAVES

With North Korea testing missiles at a steady pace, the Bulletin has been checking in regularly with Siegfried S. Hecker, the former director of the Los Alamos National Laboratory who has visited North Korean nuclear facilities multiple times. We talked to him again after last Sunday, when, as many Americans enjoyed the Labor Day long weekend, Pyongyang conducted a powerful underground nuclear test, its sixth ever and first in a year. The device detonated may or may not have been a hydrogen bomb, but we do know it was significantly more powerful than any nuclear weapon North Korea has tested before. In this interview, Hecker weighs in on what this means, what the North is capable of, and how to get out of the dangerous game of nuclear brinksmanship now embroiling Northeast Asia and the United States.

BAS: To the general public, there has been so much nuclear news out of North Korea lately that this one might sound like “just another test.” So please put it in context for us: What was different about North Korea’s September 3rd nuclear test? How did it differ in magnitude from previous tests, and what does that tell us?


SH: The destructive power of North Korea’s previous five nuclear tests had progressed to about 25 kilotons, roughly the same as the bomb dropped on Nagasaki in 1945. This test was greater than 100 kilotons; that’s a big deal. It indicates they have progressed considerably beyond primitive fission-bomb technologies.

BAS: Was this one really a hydrogen bomb, and how would we know?

SH: The size of the blast was consistent with a hydrogen bomb—that is, a fusion-based bomb. However, it could also have been a large “boosted” fission bomb, in which the hydrogen isotopes deuterium and tritium were used to enhance the fission yield. If any telltale radioactive debris leaked from the underground test site, that could help us differentiate, but so far none has been found. So we can’t be certain.

BAS: What would it mean if it was a hydrogen bomb? Would that be a game changer?

SH: No, I don’t see a hydrogen bomb as a game changer. The North has been steadily enhancing its nuclear weapons in that direction. It was only a matter of time before it got there—although, if this one was a small, modern, two-stage hydrogen bomb, then I am surprised it got there so quickly. For years, I have followed the country’s steady progress on producing plutonium and highly enriched uranium, the fuels for fission bombs. And I concluded some time ago that it also has the ability to produce tritium, which is necessary for a boosted fission bomb or a hydrogen bomb.

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