Nothing against Moxie, but this stated fact is clearly nonsense. It certainly would have been terrible for a large volume of water to reach the burning core, but you're not going to get a 5MT blast from a reactor accident. It takes a LOT of things working perfectly to make a nuclear bomb explode correctly. Lots of bad things happen when reactors go critical, a nuclear blast is generally not one of them. It's the spread of contaminated matter that makes reactor accidents bad. Also, sure, explosions can happen with rapid temperature changes like one encounters in these situations, but nothing like an actual nuclear bomb.
"Only 1400 kilograms of uranium and graphite mixture would have needed to hit the water to set off a new explosion. Our experts studied the possibility and concluded that the explosion would have had a force of 3 to 5 megatons. Minsk...would have been razed." - Vassili Nesterenko, director of the Institute of Nuclear Energy at the National Academy of Sciences of Belarus.
I am not a nuclear physicist, but at least some people who are did not find this to be "clearly nonsense."
If nothing else, consider this. If all it takes to cause a 3-5MT explosion is to get uranium hot and poor water on it, why would anyone go to the effort of developing a more complex weapon? The entire Manhattan project could have been easily solved if it was this simple, and even then the Fat Man and Little Boy bombs only yielded between 13-22kT. It wasn't until 7 years after WWII that the US managed to conduct a test that broke the mega-ton barrier. More complex H-bombs are required for this.
But regardless, we're picking nits here. It's a fun read and I enjoy your stories, so I wasn't intending to pick on you.
Ignoring the plausibility of the yield, Minsk is over 150km away from Pripyat. It's impossible for a 5Mt explosion centered on Pripyat to even reach Minsk, let alone "raze" it.
