Nuclear security

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

...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...