NORTH KOREA’S NUKE TEST FLOP

[Note:  Written the day after North Korea exploded its "device," an Update with new information is now appended at the end.]

The public face of Bush Administration officials regarding North Korea’s nuclear test is a mask of utter seriousness, or "grave concern."  Behind the mask, folks are laughing their heads off.  Meanwhile, the world’s dumbest nuclear scientists – namely, those in North Korea – are terrified of what Baby Kim will do to them when he finds out the truth.

Essentially, we have a replay of the total fiasco of Baby Kim’s headline-garnering missile test launch last July.  In Climbing Fujiyama, you learned that: 

The public reaction by both the Japanese and American governments – serious anger – is tempered by the private one.  In the White House and the Kokkai (Japanese Parliament), there is a lot of laughter.  GW really had to suppress his smirk in a press conference when he noted that the dreaded Taepodong-2 (which the press calls an "Intercontinental Ballistic Missile capable of reaching the US with its 6,000 kilometer range") blew up 40 seconds after launch.

"What a bunch of bozos," is the private assessment here in Tokyo and in DC.  "All their missiles failed.  It’s even more of a spectacular flop than their Taepodong-1 test back in 1998, where the first two stages went off ok until the third stage blew up.  These clowns can now barely get their popguns off the launch pad."

Yet everyone has to bite their tongues and resist the overwhelming temptation to publicly ridicule the North Koreans and laugh in Baby Kim’s face.  Doing so would make it much harder to get international sanctions on Pyongyang.

North Korea’s claim to have successfully conducted a test explosion of a nuclear bomb on Monday (October 8) has resulted in even more public hysteria that its missile tests, and even more private laughter.  Here’s why.

South Korean news agencies are reporting that the underground explosion registered 3.6 on the Richter scale, which means the size of the explosion was equivalent to around 500 to 700 tons of TNT.

The explosive power of nukes is measured in tons of TNT-equivalent.  "Little Boy," the bomb dropped on Hiroshima was 12,500,  or 12.5kt (kilotons), while "Fat Man," the one dropped on Nagasaki was 20kt.  The largest warhead in the US nuclear arsenal, the B53, is 9mt (megatons), or nine million tons of TNT-equivalent.

A half-kiloton explosion is about 20 18-wheeler truckloads of conventional explosives.  The North Koreans claimed their test was so successful it released no radiation.  With no witnesses and no radiation leakage, do we just have to take their word for that the "test" wasn’t a fake?

No.  Since the gases produced by a chemical explosion are much cooler than those of a nuclear one, the difference will show up in the "sharpness" of the seismic pulse reading – how sharp and steep the leading edge of the reading rises.  Since such sharpness is dispersed over distance, only sensors placed very close to the explosion can determine if it has the requisite sharpness to be nuclear – such as those placed by the US Navy on the floor of the Sea of Japan right off the coast of North Korea.

Those sensors’ readings are classified and will remain so – yet the initial reaction of folks at the Pentagon tells me that the explosion was indeed nuclear, that it was not a fake but rather a colossal failure.

The North Koreans have announced their bomb was a fission implosion-plutonium device, similar to Fat Man.  The "critical mass" of plutonium required for fission to take place is between 6 to 7 kilos of more than 90% P-239 or "weapons-grade" plutonium.  Any less plutonium and you can’t get the fission process started.

The minimum explosive yield of a properly designed and built bomb with 6½ kilos of 90+% P-239 is 20kt.  For the yield to be smaller, you have to do it on purpose and be willing to waste a lot of plutonium.  That is, say you want a very small, portable tactical nuke to be used on a battlefield, with a very small yield like the M-388 Davy Crockett nuclear recoilless rifle.

The M-388 round used in the Davy Crockett weighs only 76 lbs and has a yield of just .020kt (20 tons of TNT-equivalent).  The same amount of plutonium has to be used (6 kilos or so) as a bomb yielding 1000 times more, but it’s packed with far less high-density explosives to implode the plutonium and start the nuclear reaction.

In other words, you’ve got to be willing to waste a lot of plutonium in order to make a small portable nuke.

Since Baby Kim has no intention of demonstrating to the world that he is making tiny little tactical nukes instead of big warheads to put on ICBMs with which to threaten America, a miserable half-kiloton yield means his scientists screwed-up big time.

We saw why back in March, 2004 with Is North Korea Faking It?: 

The North Koreans don’t really know what they are doing, were pushed too hard to reprocess uranium fuel rods into plutonium, and left the rods in too long.

The longer you leave the rods in the reactor, the more uranium will be converted into plutonium — but the ratio of isotopes changes.

You need plutonium that is 90% of the 239 isotope to get the reaction to assemble fast enough for a nuclear explosion. More than 10% of the 240 or 242 isotopes and the reaction "fizzles."

So it looks like what happened Monday is this:

The (at least) 6 to 7 kilos of plutonium in the North Korean bomb contained too much 240/242, which produced so many extra neutrons when the packed explosives went off that the reaction disassembled ("fizzled" or went off prematurely), resulting in a yield of less than 3% of what it should have been.

Which means that Baby Kim and his scientists are the laughingstock of all the scientists at the Pentagon, and the world community of weapons physicists.  It’s safe to say that Baby Kim won’t take his being laughed at with a great deal of grace and equanimity.  So it’s probably a safe bet that the lifespan of his scientists (and their families) may be soon abbreviated.

This would be very good news.  Once Baby Kim kills them off, it will be hard to find replacements – and impossible to get ones smarter and more competent.  Far more likely is that he’ll get ones even dumber than the ones he has now.

Even better news is that the North Korean plutonium stockpile is worthless.  Too polluted with P240/242, bombs can’t be made of it, so it can’t be sold as such to other rogue states.

So don’t expect the slightest concessions from Bush and Condi.  They have to pretend that North Korea is in fact right now an exceedingly dangerous nuclear threat in order to get the international sanctions on it required to prevent it from becoming such a threat one day.

But behind the diplomatic pretense there is laughter – and via discrete back channels, Baby Kim is being made aware of it.  What happens when the world’s greatest egomaniac becomes a joke?  This is going to be interesting to watch,

UPDATE (Thursday, October 12):

By now it is commonly acknowledged that NK’s test was mysteriously low-yield.  A diversionary explanation is being given out and innocently carried by the media such as the Washington Post.

The Post’s Wednesday October 11 edition headlined “US Waits for Firm Information on Nature and Success of Device,” stated Bush Administration “officials believe the low yield probably resulted from the poor design of the device.” 

It goes on to describe how complicated the firing sequence must be to set off the explosives around the plutonium core simultaneously, and if the sequence is off, then “only part of the plutonium is imploded, resulting in the low yield of the North Korean test.”

Given modern computers and solid-state electronics, this explanation is not credible. The sequence requires firing the detonation circuits for each explosive charge within roughly 10 nanoseconds of each other ( a nanosecond is one-billionth of a second).  More than that and the resultant “jitter” will result in partial implosion. 

Such nanosecond timing is trivial for any decent computer you can buy at Circuit City or Best Buy.  There’s little chance the NK scientists could misstime the sequence.  So the explanation is a diversion, as the Bushistas don’t want it known that NK plutonium is polluted.

The main reason is that the current international outrage over the test can be effectively used for efforts to collapse the regime.

A second is an exception to the worthlessness of polluted plutonium as mentioned above: Iran. 

Iran is in the process of building and acquiring a “centrifuge cascade,” hundreds or even thousands of centrifuges to process natural uranium, which is 99.3% U-238 and contains only .07% of the U-235 isotope, into 90+% of weapons grade U-235 from which a bomb can be made.

This is laborious, taking metric tons of uranium.  A short cut would be to use the North Korean plutonium however polluted.  The Iranian centrifuge cascade can separate plutonium isotopes just like uranium isotopes, would need only kilos instead of tons, and could do so in less than a year (rather than several years with uranium).

(You make plutonium in a reactor, which gives out lots of heat and makes a lovely target for cruise missiles.  The centrifuges can be dispersed in many locations, all small and unseen.  The only reason to do this is to avoid attack from people who don’t want you to have nuclear bombs.)

North Korea does not have such a centrifuge cascade, so its plutonium stockpile remains worthless.  Baby Kim has no nukes and cannot make them – unless he got Iran to reprocess his plutonium.

Iran’s cascade, while not yet big enough to process enough uranium, could already do so for plutonium.  So the time to go after both of these rogue regimes and collapse them is now.  

There is a third reason which makes going after Baby Kim and his regime even more urgent.  Enraged that he can’t make bombs with his plutonium, he could sell it to Al Qaeda to make dirty bombs. 

A plutonium dirty bomb exploded in a city would wreak far more havoc than a uranium one.  That is no laughing matter.  The lunatic regime of Baby Kim’s has got to be liquidated, and very fast.