Good bomb, bad bomb

Last Sunday’s New York Times ran a story about nuclear tests.  In earlier first tests of such devices, the countries conducting them did all they could to hide preparations and hide the site itself.  Of course new satellite technology makes that much harder than it was a few years ago, but Korea made no secret that it planned to test a nuke in the next few days.  One of the reasons for secrecy is to prevent the world from knowing you failed. Korea may have failed.  Some doubt remains as to whether there was actually a nuclear explosion or whether it was a partial dud.  The word “dud” when applied to nuclear devices describes the complete failure to produce a nuclear yield.  

Nuclear bombs are of two designs. One, like the Uranium bomb that devastated Hiroshima was like a canon, firing a chunk of U235 down a tube toward another slug of the isotope.  Plutonium bombs use the implosion of a sphere of that element that requires multiple explosive charges fired in precise sequence.   In either case, a slight flaw in the sequence or some other design flaw produces a meltdown of the fissionable materials before the entire mass becomes critical.  The nuclear yield may be far less than optimal.  

If the yield of the North Korean bomb was only half a kiloton, several possibilities present themselves: it was a conventional chemical explosion of half a kiloton; it was a highly sophisticated and miniaturized nuclear bomb designed for a sub kiloton yield,  it was a partial dud yielding far less than it was designed to do.

Although the second option would be the most frightening, since such a device could be loaded onto a small missile or be delivered in many clandestine ways, it’s the least likely given the level of North Korean technology.  A complete fraud is possible, whether it was intended to fool the leisure suit wearing dictator with the bad haircut or to fool the world, but my guess is that it was a bad bomb which means that a deliverable weapon may be a number of years away. There may be time.

Now if we only had a government that hadn’t lost all credibility and wasn’t the laughing stock of the planet.