On April 26, the Chernobyl reactor in the Soviet Union exploded, releasing the largest uncontrolled radioactive material in history. Environment Canada scientists helped predict the spread of the fallout across Europe and the Western Soviet Union, aiding the relocation of 135,000 people. The explosion killed two workers, while 134 staff and emergency responders suffered acute radiation syndrome (ARS), with 28 later dying. This disaster heightened public fear and temporarily stalled nuclear energy development.

In 1955, the first International Conference on the Peaceful Uses of Atomic Energy in Geneva marked a turning point for global nuclear cooperation. Attended by over 1,400 delegates from 73 nations, it presented 1,000+ scientific papers and spurred the creation of many nuclear organizations still active today.