Ammonium nitrate isn’t dangerous.
It’s not gunpowder, it’s not rocket propellant, it’s not liquified natural gas
you need extreme heat and fuel to make it detonate, in the Beirut case that was given by nearby stored fireworks, but otherwise it’s pretty safe to use, you can blast it with a blowtorch and it doesn’t even burn
The misconception of it being explosive comes from the fact that people buy it as fertilizer and then use it to make bombs by mixing it with fuel and other primary and secondary explosives (or just to have some fun with homemade gunpowder), and even then, usually you use potassium nitrate, a derivative of ammonium nitrate, because the ammonium nitrate is just so goddamn hard to detonate
Now, should they accept the ship? I don’t know, as far as I know Russia’s regulations might as well allow storage of ammonium nitrate inside the ship’s fuel tanks, but some simple checks would mitigate 99.99999% of risks.
That said, it’s still Russia and we shouldn’t be giving it money anyways, but I’m not gonna get into politics here
The rain would quickly render it useless as an explosive, and if it was inside a container the metal would shield it
and even then, ammonium nitrate is just an oxidiser, (in layman’s terms, it makes already flammable stuff burn faster when ignited, so fast that in some cases it detonates), and without fuel it can’t do anything on it’s own