When I read about how CANDU (heavy water moderated reactor) works I started wondering why we ever build any other kind of large scale reactor.
Runs on natural uranium. Can burn waste too, and plutonium, and even thorium (mixed in, not pure, but still). It’s like a flex fuel reactor. It’s very safe and reliable.
Why do we bother with any other design? Except maybe fast breeders or fission fusion hybrids but those are whole new directions.