That explosion in Texas

It seems that they had a lot of ammonium nitrate. 270 tons of it... From Reuters:

Texas fertilizer company didn't heed disclosure rules before blast
The fertilizer plant that exploded on Wednesday, obliterating part of a small Texas town and killing at least 14 people, had last year been storing 1,350 times the amount of ammonium nitrate that would normally trigger safety oversight by the U.S. Department of Homeland Security (DHS).

Yet a person familiar with DHS operations said the company that owns the plant, West Fertilizer, did not tell the agency about the potentially explosive fertilizer as it is required to do, leaving one of the principal regulators of ammonium nitrate - which can also be used in bomb making - unaware of any danger there.

Fertilizer plants and depots must report to the DHS when they hold 400 lb (180 kg) or more of the substance. Filings this year with the Texas Department of State Health Services, which weren't shared with DHS, show the plant had 270 tons of it on hand last year.

What raises my hackles is that DHS has the threshold of reporting set way too low. 400 pounds is the annual order for a very small farm. Why is DHS requiring this data from every single mom and pop farm in the United States -- why do they consider this to be their jurisdiction? We just went through a similar thing a few years ago with the NAIS program (here, here, here and here. The last link goes to the NoNAIS.ORG website and they are showing the same kind of behavior that all too many other advocacy groups show -- the victory was won but did they pat themselves on the back and disband? No -- NAIS is dead and gone but NoNAIS is still active and soliciting funds for operation. Time to drive a stake through its beating little heart...) Anyway, the article goes on:

Chemical safety experts and local officials suspect this week's blast was caused when ammonium nitrate was set ablaze. Authorities suspect the disaster was an industrial accident, but haven't ruled out other possibilities.

The fertilizer is considered safe when stored properly, but can explode at high temperatures and when it reacts with other substances.

"I strongly believe that if the proper safeguards were in place, as are at thousands of (DHS) CFATS-regulated plants across the country, the loss of life and destruction could have been far less extensive," said Rep. Thompson.

Ammonium nitrate by itself at room temperature is pretty stable. The problem is that it starts to disintegrate when it hits the right temperature and this disintegration is very exothermic. If the material is confined, the runaway fire will result in a detonation. The explosion in West, Texas is not the first for Texas and not unique around the world.