Nuclear Reactor Day (Genshiro no Hi)

What Is Nuclear Reactor Day?

December 2 is "Nuclear Reactor Day." It commemorates December 2, 1942, when the world's first nuclear reactor, "Chicago Pile-1" (CP-1) — built beneath the stands of Stagg Field at the University of Chicago — achieved criticality, the state in which a nuclear fission chain reaction becomes self-sustaining. This achievement, accomplished by a team led by Dr. Enrico Fermi, marked the dawn of the nuclear age.

The Light and Shadow of Nuclear Power

The success of CP-1 in controlling fission energy was later applied to the Manhattan Project (the development of the atomic bomb), leading to the atomic bombs dropped on Hiroshima and Nagasaki in 1945. On the other hand, beginning in the 1950s and '60s, the peaceful use of nuclear power for electricity generation began, and today nuclear power still supplies about 10% of the world's electricity.

Japan and Nuclear Power

• 1963: Japan achieved its first nuclear power generation in Tokai Village, Ibaraki Prefecture
• Peak years: 54 nuclear reactors operated nationwide, supplying about 30% of Japan's total electricity
• 2011: Following the Great East Japan Earthquake and the Fukushima Daiichi nuclear accident, all reactors were shut down, with a gradual restart process since
• Today: Discussions continue over how to use nuclear power within the context of carbon-neutral policy

Nuclear Reactor Day is a day to reconsider the benefits and risks of nuclear energy from scientific, ethical, and policy perspectives.