North Korea Air Sample Shows Radiation

Apocalypse111 writes, "According to CNN.com, air samples taken over North Korea have not yet shown any radiation from the event on Monday that North Korea claims was a nuclear test. This is not definitive proof that the event was non-nuclear, as it may either have been so small and deep that it did not let any radioactive debris escape, or perhaps the North Koreans sealed the site." Furthering speculation over whether North Korea has actually exploded a nuclear device, vk38 writes to point out a (free) article in today's Wall Street Journal claiming that the blast could have been set off by exploding fertilizer (ammonium nitrate). The article points to the Texas City disaster of 1947, in which 7,700 tons of ammonium nitrate exploded in the hold of a ship with the estimated power of 2 to 4 kilotons of TNT.
Update: 10/14 08:03 GMT by Z : The story at CNN has been updated: "A preliminary analysis of air samples from North Korea shows 'radioactive debris consistent with a North Korea nuclear test,' according to a statement from the office of the top U.S. intelligence official."

Comments

Chemical explosion, is my bet

[Dr. Zowie]

It's not so hard to pile up ten thousand tons of conventional explosive, and as discussed in the previous thread on the test itself there is some value in convincing your neighbors that you have nuclear weapons regardless of whether you actually have them.

The revised seismic figures were (if I recall right) something like 0.5 kT equivalent. The smallest easy-to-build bombs (those that have supercritical assemblies without hyper-compression of the metal) yield something like 10-30 kT, so this was either a fizzled nuke or a large pile of ANFO (or something like that).

In the last discussion I made a big deal about the Kamioka observatory and how they "should" have been able to see neutrinos from the blast -- but with an 0.5kT blast the number of neutrino interactions is only 1 or 2, so they can't be expected to distinguish a large chemical explosion from a very small fizzled nuclear explosion.

Re:Chemical explosion, is my bet

[Vellmont]

I find it very implausible that it could have "fizzled." It's a damn chain reaction - set it and forget it, as the saying goes.

Then you need to learn a bit more about nuclear physics. Plutonium is a bit trickier to set off as a nuclear weapon do the fact that it can start a reaction before it's compressed down to the intended size. What happens is the chain reaction stops short of the intended yield because the ball of plutonium literally blows itself apart before you get enough generations of neutron reactions to yield enough energy.

Re:Chemical explosion, is my bet

[AJWM]

We had a departmental meeting about this the other day where a bunch of nuclear engineering professors got together and discussed what they thought had happened.

You should have called in some mining engineers. Your analysis is a bit off.

The speeds involved were close enough -- although the detonation of 500 tons of TNT takes about half a millisecond and given your energy for the neutrons that takes closer to a microsecond -- but either kind of explosion has to couple the energy to the rocks surrounding and propagate out from there as seismic waves for the seismic people to detect it. That coupling is going to be affected by the precise nature of the surrounding rock -- density, water content, etc. Without knowing that, it will be hard to tell the difference even with good seismic signals (or a much more powerful blast).

There were only (as I recall) a few stations that even detected the blast, enough to triangulate it but not enough for really good signal data. Good enough to tell that it was an explosion rather than an earthquake, but not to determine the kind of explosion.

Re:Halifax Explosion!

[nasor]

The Halifax explosion was only around 2 kt, two orders of magnitude less than the 200 kt figure that you claim.

Instead of very large accidental explosions, it might be a bit more topical to talk about known instances in the past where nations have deliberately simulated nuclear bombs with conventional explosives, like the 4 kt Minor Scale experiment: http://en.wikipedia.org/wiki/Minor_Scale_(explosio n)

Re:Halifax Explosion!

[QRDeNameland]

There was a larger deliberate explosion in Canada: the explosion of Ripple Rock, off Vancouver Island in 1958. It used 1,375 tons of explosives.

I have seen the Ripple Rock explosion characterized as the "largest man-made non-nuclear explosion ever" or the "largest peacetime man-made non-nuclear explosion ever."

You can watch the CBC footage here.

Re:Of course they don't

[Kagura]

UPDATE ON THIS STORY AS OF 8:30PM EASTERN:

US has evidence of radioactivity from North Korea

According to CNN, radiation has been detected

[Deslock]

U.S. intelligence statement: N. Korea radioactivity detected

From http://www.cnn.com/2006/WORLD/asiapcf/10/13/nkorea .test.sample/index.html

WASHINGTON (CNN) -- A preliminary analysis of air samples from North Korea shows "radioactive debris consistent with a North Korea nuclear test," according to a statement from the office of the top U.S. intelligence official.

The statement, from the office of Director of National Intelligence John Negroponte, was sent to Capitol Hill but not released publicly. CNN obtained it from a congressional source.

If confirmed, the nuclear weapons test that North Korea claimed it conducted on Monday would be the first of its kind since Pakistan's underground blast in 1998.

Pyongyang's claim has renewed fears of a regional arms race and that North Korea might aid terrorists with nuclear materials or technology.

The national intelligence office statement said the air samples were collected Wednesday, and analysis found debris that would be consistent with a nuclear test "in the vicinity of Punggye" on Monday.

"Additional analysis is ongoing and will be completed in a few days," the statement said.

The South Korean Defense Ministry told CNN that the United States has informed it that radioactivity has been detected.

The report is in contrast to information provided to CNN earlier Friday from two U.S. government officials with access to classified information. Those officials said that an initial air sampling over North Korea showed no indication of radioactive debris.

The White House said it had no confirmation that the North Koreans conducted a nuclear test.

"We've seen the various press reports," said National Security Council spokesman Fred Jones. "We still have no definitive statement on the event. The intelligence community continues to analyze the data."

The U.S. Air Force flew a WC-135 Constant Phoenix atmospheric collection aircraft on Tuesday to collect air samples from the region.

The intelligence community and the military will also continue to collect air samples in the region and use satellite information to try to collect radiological data that would confirm a nuclear test, officials said. But as time goes on, it will be increasingly difficult to achieve confirmation.

Officials emphasized earlier Friday that the data collected are preliminary and provide no conclusive evidence about the North Korean event.

It is possible there was no radiological data. That could be the case if: the North Koreans successfully sealed the site; it was such a small detonation and so deep underground there was no escape of nuclear debris; or the test was actually conventional explosives.

The U.N. Security Council has agreed to vote Saturday on whether to impose sanctions on North Korea over the purported nuclear test, according to John Bolton, the U.S. ambassador to the United Nations.

CNN's Suzanne Malveaux, Jamie McIntyre and Barbara Starr contributed to this report.