While we race to decarbonize the world economy, one carbon-free source of energy has fallen largely out of the conversation: nuclear energy. It’s expensive. It’s dangerous. It generates a lot of toxic waste of its own. At the same time, there’s a new generation of reactors, and the numbers of students earning degrees in nuclear engineering is back to levels not since since the 1980s. We take a good, long look at the most controversial source of clean energy.