Nuclear Vision - Can It Happen in Nature?

Nuclear vision is when you break up a heavy atom into lighter atoms. Can that happen naturally in nature, and more specificly, can you like, have a reactor of it that creates a bunch of energy? We've a chain reaction, a self sustaining reaction, sort of like fire. That's a very special arrangement, which only in this century we were able to engineer to make happen. But getting into like best self staining and have it to be like a fire were it's constantly happening, that's harder. It's like the difference between having a spark and having a fire. To get a fire started, you need to get enough heat so that youare igniting more