^ You were, essentially. Wow. A chink in your thinking. Gnats, nuts.
So with a sufficient size pile, you get tactical nuke level explosions?
...
Sorta yes.
While not AN, but other conventional explosives, see "Trinity Test Calibration shot" and "Operation Minor Scale,"
et cetera for examples of conventional explosives used to simulate nukes.
The former involved TNT and the latter ANFO (fuel oil mixed with the AN.)
^Minor Scale
The W54 was one of the smallest nuclear warheads deployed by the United States. It was a very compact implosion-type nuclear weapon design, designed for tactical use and had a very low yield for a nuclear weapon, in the range of 10 to 1,000 tons TNT equivalent. (wiki)
So yes. sorta, (There were some explosive equivalencies stated earlier in this thread.)
Your risk assessment is off-kilter and AN ain't safe and large quantities should be stored in properly engineered magazines.The point is this: It doesn't matter how it went off, whether from internal fires, or aerial salutes getting in, or cigarettes wrapped in candy bar wrappers, or lightning strikes, or ship collisions, or spontaneous combustion...
It friggin' went off.Viz, Beirut, 04 August 2020, 15:08:18 UTC, viz Texas City, viz Halifax...
It friggin' went off.Terry said that and he ain't takin' it back.