EDIT: the accuracy I am referring to is about the actual sequence of events of the plot, which I understand to be simplified as people replying have pointed out :)
EDIT: the accuracy I am referring to is about the actual sequence of events of the plot, which I understand to be simplified as people replying have pointed out :)
By and large, the creators always tried to be biased away from the fantastical elements. That is, they left parts out of the movie, that while 100% true, just sounded too unrealistic.
I agree, though, I love how many tiny things that are actually true they managed to squeeze in there. As another example, the part where the firefighter's wife bribes her way into the closed hospital in Moscow - that really happened too.
[1] https://www.businessinsider.com/chernobyl-volunteers-divers-...
Perhaps it was indeed wrong, but it sounds like that might be actually what those involved believed at the time.
A nuclear explosion would require Uranium enriched to at least 85%, whereas the fuel in RBMK reactors was only enriched to 2%. It's not just unlikely it's actually impossible.
In the case of Chernobyl, the concern was that upon contact with water (which acts as a neutron moderator in these circumstances) and given the inevitable sequence of steam explosions that would follow, some regions of superheated corium might be forced into prompt criticality events. These would technically qualify as nuclear explosions, but the sequence of events required to get from this set of increasingly improbable assumptions to anything remotely close to a megaton range explosion is, as I said, improbable to the point of being trivially dismissable.
[1] EDIT: I realized I should probably point out for clarity that I'm referencing the traditional measures for a critical mass - the mass required for a homogenous sphere of a given material to go critical. Determining the critical mass for a highly inhomogenous material of complex geometry, highly varied temperature and potentially surrounded by neutron reflecting substances is not a trivial task.
But yes, certainly the melted fuel becoming critical and/or causing more steam explosions could have made the Chernobyl accident worse than it already was.