“Thirty-five years after the Chernobyl Nuclear Power Plant in Ukraine exploded in the world’s worst nuclear accident, fission reactions are smoldering again…
“Now, Ukrainian scientists are scrambling to determine whether the reactions will wink out on their own—or require extraordinary interventions to avert another accident.”
https://www.sciencemag.org/news/2021/05/nuclear-reactions-reawaken-chernobyl-reactor