That's why this crisis is a major risk for Europe right now. One shell in a wrong place and Chernobyl 2.0 is happening. The nuclear tech has improved there but not that much. There are still reactors with no concrete structure encapsulation.
Weren’t Chernobyl’s remaining reactors shut down on 2000? That would presumably make the risk from an accident similar to that from dirty bomb (so localised) not a nuclear meltdown.