In nuclear fission, the fissile atom splits into smaller atoms, releasing energy in the process. The smaller atoms have too many neutrons so they arent super stable but they kind of pass the extra neutrons around and remain radioactive, launching neutrons and gamma rays out of the spent fuel for like 10,000 years. It’s waste because the smaller atoms aren’t fissile and they are too radioactive to be used in most chemistry. I failed physics and chemistry so dont quote me.
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