There's a pretty succinct (2 minute) non-engineering description of how a nuclear reactor works in the Chernobyl miniseries you might want to check out: https://www.youtube.com/watch?v=BpwU4mtWXAE
In context - the scientist had basically said that the politicians and their bureaus were all wrong, that it wasn't a minor incident, and "accused" them of lying, covering up, and/or being willfully ignorant and stupid.
The whole show isn't like that, but it does try to show that so much of the issue was caused by a desire to be seen as infallible (of course the reactor design wasn't flawed, because the people's greatest minds worked on it, etc., etc.) and that was something that had to be dealt with atop the actual disaster.
Either way, far more people die prematurely every day from causes due to pollution from coal-fired plants. But if you're a journalist or documentary filmmaker trying to make something look all cool and edgy and scary and shit, an exploding nuclear power plant makes for a much more interesting story than just another day in the pulmonary ward.
If not for some very edgy heroics, it would have been millions, and most of Ukraine down to the Black Sea uninhabitable for centuries. What did happen was not just "because nuke", but because of a whole series of design and management failures, very far from the least of which was denialism.
They did finally fix the cause of the explosion in the other reactors of that design, remarkably many years later.
Nobody here will defend coal, but graphite-moderated reactors are not the tech you want to be defending.
