In the post-World War II era, nations were eager to harness the power of atomic energy, both for military applications and to meet energy demands. The Soviet Union, having recognized the potential of nuclear fission early on, embarked on an ambitious project to develop nuclear reactors. The F-1 reactor, designed and constructed at the Institute of Atomic Energy in Moscow, was the culmination of years of research and experimentation. Spearheaded by Igor Kurchatov, often referred to as the 'father of the Soviet atomic bomb,' the project aimed not only to explore the scientific possibilities of nuclear power but also to demonstrate the USSR's scientific and technological prowess to the world.On Christmas Day in 1946, the F-1 reactor achieved a remarkable breakthrough by producing a self-sustaining chain reaction. This key achievement demonstrated not just the technical feasibility of nuclear energy but also set the stage for subsequent developments in both nuclear energy production and weapons development within the Soviet Union. The successful chain reaction was a powerful statement of progress and capability, solidifying the Soviet Union's place in the global race for nuclear technology.As the F-1 reactor became operational, it paved the way for future reactors and contributed to advancements in both military and civilian nuclear technology. The event was celebrated within the scientific community and laid a foundation for the Soviet Union's future achievements in the nuclear realm, influencing nuclear policies and energy strategies for decades to come.