Eli5 why do we not use reactor waste to make power?

Question

Reactor waste remains hot as waste so why do we not pile it in a massive dump and cirulate water through it to raise steam or at least preheat water for heat generation?

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Thanks everyone for an informative and interesting discussion.

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In: 337

Answer 1

Totally a thing, and a viable option. But , it would require reworking most of the current plants.