Resolved with the things the OTL British government did to make sure it wouldn't happen again. It hasn't happened again.
As for why it did didn't discredit coal, the main reason is that this occurred after people broke the rules by dumping spoil on springs of water. This wasn't an event that could be turned into 'if we continue to mine coal, this is guaranteed to happen at some point'.
Chernoybl was a badly designed reactor that had a type of meltdown which wouldn't happen with most reactors. That didn't keep it from discrediting nuclear power.
What's actually the case and what culture imagines dangers to be are radically different things there. This thread has really taught me the value of psychology here, to put things mildly.