1952 Naval Reactors at Chalk River - Focus Paper

This 2025 Naval Reactors Historical Association Focus Paper takes a detailed look at the 1952 reactor accident at the Chalk River NRX reactor near Ontario Canada. On December 12, 1952, a confluence of design flaws, operator error, and mechanical malfunction culminated in a partial meltdown at the NRX reactor—the most severe nuclear accident to that date. The event would have profound consequences not only for Canada’s reactor safety practices but also for the design and operational philosophies that Rickover implemented across the U.S. Navy’s nuclear propulsion fleet. The article draws from 1952 post event reports, Duncan books, and Canada articles.