Nuclear Timeline
From the discovery of radioactivity in 1896 to fusion ignition in 2022: the complete history of the nuclear age.
Henri Becquerel discovers radioactivity in uranium salts. Marie and Pierre Curie coin the term and discover polonium and radium.
Albert Einstein publishes Special Relativity, establishing that mass and energy are equivalent - the theoretical foundation for nuclear energy.
James Chadwick discovers the neutron, the key particle for nuclear fission. He wins the Nobel Prize in 1935.
Otto Hahn and Fritz Strassmann split uranium atoms for the first time in Berlin. Lise Meitner and Otto Frisch explain the physics.
Albert Einstein writes to President Roosevelt warning of German nuclear ambitions. The US begins secret nuclear weapons research.
Chicago Pile-1, the world's first artificial nuclear reactor, achieves criticality under Enrico Fermi at the University of Chicago.
The US drops atomic bombs on Hiroshima (Aug 6) and Nagasaki (Aug 9), killing an estimated 110,000โ210,000 people. Japan surrenders, ending WWII.
The USSR detonates "Joe-1", its first nuclear bomb, ending the US nuclear monopoly and beginning the Cold War arms race.
The US detonates "Ivy Mike", the first true thermonuclear weapon (H-bomb) at Enewetak Atoll - 1,000ร more powerful than Hiroshima.
President Eisenhower addresses the UN proposing civilian nuclear power. Sets the stage for nuclear energy as a global peacetime technology.
The Obninsk Nuclear Power Plant in the USSR becomes the first to generate electricity for the grid - 5 megawatts. The nuclear age begins.
The International Atomic Energy Agency is created to promote safe nuclear use. The same year, the Kyshtym disaster in the USSR (INES 6) contaminates 15,000 kmยฒ.
Britain's first nuclear reactor fire releases radioactive contamination across the UK and Europe. The worst nuclear accident in UK history.
The USS Nautilus, the world's first nuclear-powered submarine, completes the first submerged transit of the North Pole.
The USSR detonates the Tsar Bomba - at 50 megatons, the largest nuclear weapon ever tested. Its shockwave circled Earth three times.
Three US Army nuclear reactor operators killed in Idaho in the first fatal nuclear reactor accident in American history.
The US, USSR and UK sign the PTBT, prohibiting nuclear tests in the atmosphere, space and underwater. A first step toward non-proliferation.
The NPT is opened for signatures - the cornerstone of global efforts to prevent the spread of nuclear weapons.
Nuclear power expands rapidly. By 1973, 16 countries operate reactors. Public confidence in nuclear energy reaches its peak.
Scientists discover Oklo, Gabon - a natural nuclear fission reactor that operated for 150,000 years, roughly 1.7 billion years ago.
America's worst nuclear accident. A partial meltdown at Pennsylvania's TMI-2 reactor triggers a nationwide crisis of confidence in nuclear power.
Reactor No. 4 at Chernobyl explodes. The worst nuclear disaster in history (INES 7) releases 400ร the radiation of Hiroshima. 350,000 evacuated.
The USSR dissolves, raising urgent nuclear security concerns. Thousands of warheads are secured across 15 successor states.
The CTBT is adopted by the UN General Assembly, banning all nuclear explosions. 178 nations have since ratified it.
North Korea withdraws from the NPT and resumes its nuclear weapons program, creating an ongoing geopolitical crisis.
North Korea conducts its first nuclear test. The explosion is detected worldwide. The UN imposes sanctions.
Japan's 9.0-magnitude earthquake and tsunami trigger three nuclear meltdowns. INES 7. 154,000 evacuated. No direct radiation deaths.
Iran agrees to limit its nuclear program in exchange for sanctions relief. A landmark diplomatic agreement later withdrawn by the US in 2018.
122 nations adopt the TPNW - the first legally binding instrument to comprehensively prohibit nuclear weapons. Nuclear-armed states boycott.
The Treaty on the Prohibition of Nuclear Weapons becomes international law after 50 ratifications, though major nuclear powers remain outside it.
The US National Ignition Facility achieves nuclear fusion ignition - producing more energy than the laser energy used to trigger it. A historic milestone.
Major tech companies (Microsoft, Google, Amazon) sign deals for nuclear power to fuel AI data centers. Small Modular Reactors advance toward deployment.