Items mentioned in the news report so far: ammonium nitrate, fuel oil, liquid propane gas, and dynamite.
Maybe all of them or maybe some of them, who knows?
Here is the quote from the thread source that TheLion posted in #16:
"According to an UN Office For The Coordination Of Humanitarian Affairs Report from 24 April 2004, the explosion resulted from the contact of two train wagons carrying ammonium nitrate with a wagon containing fuel oil. Each wagon contained 40 MT [metric tons] of ammonium nitrate which were enroute to a construction site for the Pakma-cheol san irrigation project. This resulted in a massive explosion creating a large crater and leveling everything in a 500 m radius." (emphasis and clarification added)The problem with the above account is the following...
The percentage of fuel oil required to turn to ammonium nitrate into the explosive ANFO, is surprisingly low (in deference to Jim Robinson and Free Republic, please refrain from asking about, or posting, the percentage). But in the UN account quoted above, the percentage of fuel oil looks like it must have been on the order of about 50%. This is a far greater percentage of fuel oil than can be tolerated by an ANFO mix.
The result would be to make the mixture nearly immune from detonation, and if it did detonate, the energy release would be severely limited. I've seen the laboratory test results of what a change of just 1/2% can do to sensitivity and energy release in an ANFO mixture. It is significant. ANFO is hard enough to detonate, without adding this additional impediment to it.
Yet when we look at the pictures that TigerLikesRooster posted here and the others available at the GlobalSecurity.com website she linked this thread to, we see that the detonation was anything but a "limited", low energy event.
The history of ammonium nitrate is the history of massive accidental explosions. Many of those events, like this one, did not have the optimum mixture of fuel oil and ammonium nitrate either, yet they detonated. But in those cases the explosions were preceded by many hours (sometimes days) of intense fire that heated the mixture to such high temperatures that it enabled a detonation to occur. By the news reports I've seen, this was not the case in the Ryongchon event.
TigerLikesRooster mentioned in post #18 that some of the earlier news reports spoke of, among other things, the presence of "dynamite" on the train, but for at least two reasons, that, by itself, is not very significant.
First, some have speculated that if dynamite were present, that might explain the detonation of the ANFO, but while dynamite is sometimes used to detonate ANFO, you would also need blasting caps to detonate the dynamite (blasting caps, alone, will not detonate ANFO). Fire will occasionally detonate some higher NG grades of dynamite, but not all grades. And, to repeat, I've read no reports of fire prior to the detonation.
Now if there had been dynamite on the train and some genius had stored the blasting caps in intimate proximity to the dynamite (now that would have been a real "Darwin Award" decision!) and somehow they managed not to detonate until after the fuel oil and ammonium nitrate had been mixed...well you get the idea.
Second, the term "dynamite" is the lay term for almost any non-military explosive. Since this shipment of ammonium nitrate was intended to be used as an explosive, rather than as a fertilizer ("enroute to a construction site..."), it would not be at all surprising to hear reporters refer to the ammonium nitrate as "dynamite" (stupid, but not surprising).
Since all the eye witnesses to the tragedy are now (presumably) just so much dust wafting across the Sea of Japan at about thirty thousand feet, perhaps we will never know for sure what happened. Maybe this was just a bizarre accident and not an intentional event, but I wouldn't be too quick to write this off as just another tragic ammonium nitrate accident. Not just yet, anyway. (Though I suspect I'm preaching to the choir with that caution.)
--Boot Hill