By Hui Zhang
Senior Research Associate, Project on Managing the Atom, Belfer Center for Science and International Affairs, Harvard Kennedy School
On February 12, 2013, North Korea conducted its third nuclear test, and a number of seismic stations around the world detected the event. Before and after the test, there has been much anticipation in the media that we might learn through off-site sampling analysis whether North Korea exploded plutonium bomb like it did in the in 2006 and 2009 tests, or a new device using highly enriched uranium (HEU).
Indeed, many experts have suggested that the test was an HEU explosion. North Korea has only a small supply of plutonium—material that it had stopped producing by 2008—and had more recently demonstrated an operational capability to enrich uranium, which would support a much larger arsenal of weapons given North Korea’s huge deposits of natural uranium. Without a doubt, confirming the type of nuclear weapon it tested is highly desirable. However, the seismic signals are useless in this regard. The question is, then, can the off-site environmental sampling analysis distinguish a plutonium explosion from a HEU explosion? Read more