Sure nuclear meltdowns making territory unusuable sucks, but the mining does actually present a fair amount of ecological damage itself, and I think there's more metrics than potential territory loss. Notably lignites causes more radiation to enter the atmosphere, but unlike nuclear, this isn't neatly concentrated in one area people can just stay out of, which isn't conducive to people not dying.
I could maybe humour the argument that nuclear waste storage (Even accounting for these being very little of it, there will be very little of it for a very long time) or especially nuclear power plants encouraging nuclear weapons development being fat tail risks, but accidents, no. We're never going to see dramatic nuclear meltdowns even get close to causing the death toll of lignite, it just is way too implausible.