Discovery of Radioactivity

1896

Henri Becquerel discovers radioactivity, laying the foundation for nuclear physics.

1932

Neutron Discovery

1932

James Chadwick discovers the neutron, crucial for understanding nuclear fission.

1938

Nuclear Fission Discovered

December 1938

Otto Hahn and Fritz Strassmann discover nuclear fission, opening the path to nuclear energy.

1942

Chicago Pile-1

December 2, 1942

First controlled nuclear chain reaction achieved under Enrico Fermi's leadership.

1945

Trinity Test

July 16, 1945

First nuclear weapon successfully detonated in New Mexico desert.

1945

Hiroshima and Nagasaki

August 6 & 9, 1945

Atomic bombs dropped on Japan, ending World War II and beginning the nuclear age.

1949

Soviet Union's First Nuclear Test

August 29, 1949

USSR detonates its first nuclear device, starting the nuclear arms race.

1952

Ivy Mike - First Hydrogen Bomb

November 1, 1952

First full-scale thermonuclear device tested by the United States.

1953

Atoms for Peace

December 8, 1953

President Eisenhower proposes peaceful uses of nuclear energy to the UN.

1954

Castle Bravo Disaster

March 1, 1954

Largest U.S. nuclear test goes wrong, yielding 15 megatons instead of expected 6.

1954

World's First Nuclear Power Plant

June 27, 1954

Obninsk Nuclear Power Plant begins operation in the Soviet Union.

1957

First U.S. Commercial Nuclear Plant

December 2, 1957

Shippingport Atomic Power Station begins operation in Pennsylvania.

1961

Tsar Bomba

October 30, 1961

Soviet Union detonates the largest nuclear weapon ever tested - 50 megatons.

1962

Cuban Missile Crisis

October 14-28, 1962

Closest the world has come to nuclear war as U.S. and USSR face off over missiles in Cuba.

1968

Non-Proliferation Treaty Signed

July 1, 1968

NPT signed to prevent spread of nuclear weapons and promote peaceful nuclear energy.

1979

Three Mile Island Accident

March 28, 1979

Partial meltdown at Pennsylvania nuclear plant becomes worst U.S. nuclear accident.

1983

Stanislav Petrov Saves the World

September 26, 1983

Soviet officer prevents nuclear war by refusing to launch missiles despite false alarm.

1983

Able Archer 83

November 2-11, 1983

NATO exercise nearly triggers Soviet nuclear response due to miscommunication.

1986

Chernobyl Disaster

April 26, 1986

Worst nuclear accident in history releases radioactive material across Europe.

1987

INF Treaty Signed

December 8, 1987

U.S. and USSR agree to eliminate intermediate-range nuclear missiles.

1991

START I Treaty

July 31, 1991

Major nuclear arms reduction treaty between U.S. and USSR.

1995

Norwegian Rocket Incident

January 25, 1995

Scientific rocket launch nearly triggers Russian nuclear response.

1998

India and Pakistan Nuclear Tests

May 1998

Both nations conduct nuclear tests, becoming declared nuclear powers.

1999

Kargil Conflict

May-July 1999

First military conflict between two nuclear-armed states.

2006

North Korea's First Nuclear Test

October 9, 2006

North Korea joins the nuclear club with underground test.

2011

Fukushima Disaster

March 11, 2011

Earthquake and tsunami cause nuclear meltdowns at Japanese power plant.

Nuclear History Timeline

Discovery of Radioactivity

Neutron Discovery

Nuclear Fission Discovered

Chicago Pile-1

Trinity Test

Hiroshima and Nagasaki

Soviet Union's First Nuclear Test

Ivy Mike - First Hydrogen Bomb

Atoms for Peace

Castle Bravo Disaster

World's First Nuclear Power Plant

First U.S. Commercial Nuclear Plant

Tsar Bomba

Cuban Missile Crisis

Non-Proliferation Treaty Signed

Three Mile Island Accident

Stanislav Petrov Saves the World

Able Archer 83

Chernobyl Disaster

INF Treaty Signed

START I Treaty

Norwegian Rocket Incident

India and Pakistan Nuclear Tests

Kargil Conflict

North Korea's First Nuclear Test

Fukushima Disaster

Explore More Nuclear History