To me what was scary was the indifference and denial of those in charge. It's not even that they were trying to cover things up, they seemed to believe the nonsense they were spouting.

"A nuclear plant can't blow up" Dyatolov would yell, but taking a look out the window to actually see what there was never seemed to cross his mind. What he knew was all that was important. His bosses had a list of who was to blame they were going to throw under the bus. It was expected. "3.6 - not great, not terrible" even though they should know that's as high the friggin device goes. The old party hack who yelled at everyone who questioned authority, and cut off the phones so no lies could be spread.

An indifferent and uncaring authority is as scary as anything can be. The show also showed how people can work together when the shit hits the fan, despite all the hacks that think they know what's best.