As far as I know, no coal plants have ever resulted in a Chernobyl-scale effect.
Coal power plants kill ten times as many people every year when functioning as designed.
FWIW I once had dinner with an architect of one of the early nuclear plants. They had been lied to about the prospects of a solution to waste disposal and no longer considered it a sensible approach.
On the other hand, it's also easy to overstate the magnitude of a disaster. To the best of my knowledge, no one actually died of radiation exposure from the accident (and probably no one will at this point). There are expected to be a number of deaths (somewhere between 15 and 1100) from increased cancer rates in the larger population. I would hope these weren't included in the "one in a million" claim.