With a fourth generation of nuclear power, you can have a technology that will burn more than 99 percent of the energy in the fuel. It would mean that you don’t need to mine uranium for the next thousand years.

Hansen is arguing for advanced (“Generation IV”) nuclear reactor designs—often fast reactors with closed fuel cycles—that can extract far more usable energy from uranium than today’s once‑through light‑water reactors. By “burn more than 99 percent,” he points to the idea that most of the energy potential in mined uranium remains unused in conventional practice, while breeder/fast-spectrum systems could fission a much larger fraction of heavy nuclei (including plutonium produced from U‑238). The claim about not needing to mine uranium for a millennium frames nuclear power as a long-duration, low-carbon energy source whose resource constraints could be dramatically eased through better fuel utilization and recycling.