By another Chernobyl they mean catastrophic nuclear accident obviously. And they can still happen, we just haven't seen how yet, it's arrogant to think we've made a full proof system using for profit companies that can't ever go wrong. I lt can, and probably will some day, whether it is a tsunami, or a volcano, earthquake, war, meteorite, terrorist attack, it's possible and not worth it when there are wind turbines solar and batteries.