The world-wide scientific analysis of the North Korean nuclear test is starting to come in, and it’s developing in an interesting direction. It appears, at least so far, that the blast was small, possibly less than 1 kiloton.
By comparison, the bomb that destroyed Hiroshima was 15 kilotons, and the United States’ first test at Trinity, over 60 years ago, was 18 to 20 kilotons. Most U.S. nuclear weapons today are capable of yields over 100 kilotons, with many in the 300 kiloton range. Much larger weapons have been built, including a variety of strategic weapons in the 5000 to 15000 kiloton range.
So what does the low yield of the North Norean test mean? I’ve heard a number of possible explanations:
Mismeasurement. Something has caused a false low estimate of the blast. As more and more people analyze the seismic shock wave, this seems less unlikely.
Fizzle. The Norks were trying for a typical 10-20 kiloton test blast, but the bomb didn’t work right, resulting in a very small blast. This seems a little unlikely because atom bombs aren’t all that hard to build once you have the fissionable materials. No other country has had a failure of their first test. Then again, this is North Korea we’re talking about. The likely launch vehicle for a nuclear weapon, the Taepodong-2 missile, failed its big test last July.
Fake. The unit of weapon yield, the kiloton, means literally the explosive power of 1000 tons of high explosive. To fake a 1-kiloton test blast, the North Koreans would simply have needed to bury 1000 tons of high explosives and set it off. Note that they were quick to announce that no radioactive materials leaked from the test site, which would certainly be true if none was ever produced.
Suitcase Nuke. The blast was small because the weapon was small. The North Koreans are developing small portable nuclear bombs that are intended to be smuggled to their targets by spies or—in the worst-case scenario—by whatever terrorists North Korea’s crazy leader sells them to.
Artillery Shell. An alternate explanation for a small weapon is that the warhead is intended to be fired by artillery, which would limit its size.
If the North Korean nuke is intentionally small, the last possibility makes the most sense.
Whenever the Daily Show has a Republican guest and they start talking about the war in Iraq, Jon Stewart likes to stump them by asking why the U.S. isn’t doing something about the serious threat of North Korea. For some reason no one ever explains it to him, even though the answer is pretty simple.
Much of North Korea’s national security depends on the fact that Seoul, the capital of South Korea, is only 30 miles from North Korea. It has 10 million inhabitants, and an additional 13 million people live in its suburbs. All of these people are within range of about 700 North Korean artillery guns and missile launchers. North Korea simply has 23 million hostages, half the population of South Korea, that it can start killing in the event of a U.S. attack.
By building nuclear weapons small enough to fire at South Korea from existing artillery and short-range missiles, North Korea would be strengthening their deterrence against an attack from the United States military.
My best guess, however, is that the North Korean nuke was a fizzle.
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