For half a century, nuclear power in the West was a story of retreat: plants shuttered, projects cancelled, a technology stranded between the fears it inspired and the costs it could never quite control. That story is now reversing, and the force behind the reversal is neither climate policy nor energy security but artificial intelligence. The data centers training and serving the world's models need electricity on a scale, and of a kind, that almost nothing else can supply, and the industry has run the numbers. The only proven source that fits is the atom.