Hiroshima bomb 75th Anniversary

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HIROSHIMA 75th ANNIVERSARY

In a flash, a changed world

It took just a few years to develop the first atomic weapon, and only weeks between the first test and its use in war. Seventy-five years later, humanity is still coming to grips with the results.

The atomic bomb that the United States dropped on Hiroshima on Aug. 6, 1945, killed tens of thousands and flattened the Japanese city in an instant.

“Little Boy,” as it was known, was the endpoint of years of research, wrangling a physics theory into a mechanism to release the energy that binds together atoms. An eyeblink, by modern standards. And it was tested only once—an event so momentous that one of the bomb’s chief scientists, Robert Oppenheimer, said it brought to mind words from Hindu scripture: “Now I am become death, destroyer of worlds.”

The concept was simple: driving together enough uranium or plutonium at high enough speeds will create a “critical mass” so quickly that it will start an uncontrolled, nearly instantaneous chain reaction of neutrons knocking apart atomic nuclei.

Each atom’s lost mass is converted to energy at a staggering exchange rate. Only 1.09 kg of the 64 kg of uranium in Little Boy became energy.

It was the equivalent of detonating 15,000 tons (13.6 million kg) of TNT, according to Los Alamos National Laboratory calculations.

Detonator

Uranium-235

LITTLE BOY

August 6, 1945. Hiroshima

Known as a gun-type fission device, it fires a mass of uranium into another to create a supercritical mass.

Initiator

Explosives

Plutonium

FAT MAN

August 9, 1945. Nagasaki

Explosive charges compress the plutonium fissile core rapidly causing fission to occur and produce an explosion.

Initiator

Detonator

Explosives

Uranium-235

Plutonium

LITTLE BOY

FAT MAN

August 9, 1945

Nagasaki

August 6, 1945

Hiroshima

Explosive charges compress the plutonium fissile core rapidly causing fission to occur and produce an explosion.

Known as a gun-type fission device, it fires a mass of uranium into another to create a supercritical mass.

Initiator

Detonator

Explosives

Plutonium

Uranium-235

LITTLE BOY

FAT MAN

August 6, 1945

Hiroshima

August 9, 1945

Nagasaki

Known as a gun-type fission device, it fires a mass of uranium into another to create a supercritical mass.

Explosive charges compress the plutonium fissile core rapidly causing fission to occur and produce an explosion.

Initiator

Detonator

Explosives

Plutonium

Uranium-235

LITTLE BOY

FAT MAN

August 6, 1945

Hiroshima

August 9, 1945

Nagasaki

Known as a gun-type fission device, it fires a mass of uranium into another to create a supercritical mass.

Explosive charges compress the plutonium fissile core rapidly causing fission to occur and produce an explosion.

About one square mile of Hiroshima was flattened, crushed by the hammer blow of Little Boy detonating about 580 metres (1,900 ft) overhead. Nearly everyone in that area died instantly. Farther away, the bomb’s heat ignited buildings and people, and deadly radiation bloomed.

Fires raged through the city. Doctors saw more cases of acute radiation sickness than at any other point in history. In the end, as many as 100,000 people were dead and more than half of the city’s buildings lay in ruins.

HIROSHIMA

In 1946, based on aerial photography, the US Army documented the destruction caused after the “Little Boy” bomb detonation over the city of Hiroshima.

Bombed areas partially destroyed

Bombed areas completely destroyed

MISASA

HOMMACHI

HIGASHI

HAKUSHIMA

CHO

Higashi

drill field

SAKAIMACHI

Regiment

Headquarters

Ground zero

City Hall

SHINONOMECHO

Nishi Junior

high school

Hiroshima

prison

Eba grade

school

Army food

depot

NIHOMACHI

Hiroshima

girls college

Hiroshima

airport

UJINAMACHI

Shipyard

Ujina station

Military piers

HIROSHIMA

BAY

UJINA-SHIMA

KANAWA

0

500m

HIROSHIMA

In 1946, based on aerial photography, the US Army documented the destruction caused after the “Little Boy” bomb detonation over the city of Hiroshima.

0

500m

Bombed areas partially destroyed

Bombed areas completely destroyed

5th Engineer

Battalion

MISASA

HOMMACHI

HIGASHI

HAKUSHIMA

CHO

Girls

high school

Higashi

drill field

SAKAIMACHI

Hiroshima Station

Regiment

Headquarters

Ground zero

FUKUSHIMACHO

City Hall

Nishi Junior

high school

SHINONOMECHO

Hiroshima

prison

Army clothing

depot

Eba grade

school

Army food

depot

NIHOMACHI

Hiroshima

girls college

Hiroshima

airport

UJINAMACHI

Shipyard

Ujina station

Military piers

UJINA-SHIMA

HIROSHIMA

BAY

KANAWA

0

500m

HIROSHIMA

In 1946, based on aerial photography, the US Army documented the destruction caused after the “Little Boy” bomb detonation over the city of Hiroshima.

5th Engineer

Battalion

Bombed areas partially destroyed

MISASA

HOMMACHI

Bombed areas completely destroyed

HIGASHI

HAKUSHIMA

CHO

Girls

high school

Higashi

drill field

SAKAIMACHI

Hiroshima Station

Regiment

Headquarters

Ground zero

FUKUSHIMACHO

Girls

high school

Nishi Junior

high school

City Hall

SHINONOMECHO

Hiroshima

prison

Army clothing

depot

Army food

depot

Eba grade

school

NIHOMACHI

Hiroshima

girls college

Hiroshima

airport

UJINAMACHI

Shipyard

Ujina station

Military piers

UJINA-SHIMA

HIROSHIMA BAY

KANAWA

0

500m

HIROSHIMA

In 1946, based on aerial photography, the US Army documented the destruction caused after the “Little Boy” bomb detonation over the city of Hiroshima.

Electric

substation

MISASA

HOMMACHI

Bombed areas partially destroyed

5th Engineer

Battalion

HIGASHI

HAKUSHIMA

CHO

Bombed areas completely destroyed

Girls

high school

Higashi

drill field

SAKAIMACHI

Regiment

Headquarters

Hiroshima Station

Ground zero

FURUE

FUKUSHIMACHO

MINAMI

KANIYACHO

Canning

factory

Girls

high school

Nishi Junior

high school

Funair

hospital

City Hall

SHINONOMECHO

MINAMIMACHI

Hiroshima

prison

Army clothing

depot

Eba grade

school

NIHOMACHI

Army food

depot

Hiroshima

girls college

Hiroshima

airport

UJINAMACHI

Shipyard

Ujina station

Military piers

UJINA-SHIMA

HIROSHIMA BAY

KANAWA

0

500m

Bombed areas partially destroyed

HIROSHIMA

In 1946, based on aerial photography, the US Army documented the destruction caused after the “Little Boy” bomb detonation over the city of Hiroshima.

Electric

substation

MISASA

HOMMACHI

USHITAMACHI

5th Engineer

Battalion

Bombed areas completely destroyed

Girls

high school

HIGASHI

HAKUSHIMA

CHO

Garrison

hospital

Isolation

hospital

Isolation

hospital

Electric

substation

Higashi drill field

KOIMACHI

Regiment

Headquarters

Hiroshima Station

SAKAIMACHI

Isolation

hospital

Ground zero

KYOSASHICHO

FUKUSHIMACHO

FURUE

Canning

factory

MINAMI

KANIYACHO

Girls

high school

Nishi Junior

high school

Funair

hospital

City Hall

SHINONOMECHO

KUSATSUMACHI

Factories

Girl’s

high school

MINAMIMACHI

Hiroshima

prison

Army clothing

depot

Firing range

Hiroshima

College

Eba grade

school

NIHOMACHI

Army food

depot

Workers

quarters

Hiroshima

girls college

Hiroshima

airport

UJINAMACHI

Shipyard

Ujina station

Military piers

UJINA-SHIMA

MORI-YAMA

HIROSHIMA BAY

KANAWA

The birth of Little Boy

The work to turn nuclear fission, a process German scientists discovered in the late 1930s, into a weapon was dubbed the Manhattan Project in the United States. Led by the U.S. Army, it involved at its peak more than 100,000 personnel, ranging from scientists to construction workers, according to the U.S. Department of Energy. Scientists first built a working nuclear reactor. The site: beneath the bleachers of the University of Chicago football stadium. The reactor, called the “Chicago Pile,” proved in 1942 that a controlled fission reaction was possible – the heart of modern nuclear power plants.

Memorial rock at the site where the second Chicago Pile reactor, CP-2, was buried in 1956. Picture by the U.S. federal government, public domain.

It began the race to enrich enough of the isotope of uranium needed – uranium 235, whose structure makes a chain reaction possible – and plutonium, another fissionable element isolated by a team at the University of California in 1940. Scientists, meanwhile, struggled on how to best create the instantaneous critical mass needed for an explosion.

They decided on two methods: firing a small piece of uranium into a larger piece in a sort of “gun” arrangement, and creating a hollow sphere of plutonium that explosives would implode, or collapse, into a critical mass. The first was Little Boy. The second was Fat Man, the implosion-style bomb that destroyed Nagasaki on Aug. 9, 1945 and killed as many as 75,000 people.

Aerial shots of the explosion of the “Fat Man” bomb and the subsequent destruction on Nagasaki. August 9, 1945. Reuters video archive.

In modern times, novel weapons are developed not just over years, but sometimes decades. The “Trinity” test evaluating the implosion-type atomic bomb was on July 16, 1945, less than two years after the Chicago Pile.

It was first used in war less than a month later.

NAGASAKI

On August 9, 1945, the B-29 “Bockscar” took off towards the city of Kokura. However, that day the city was covered by clouds, so Nagasaki was devastated instead.

Structural damage by

Structural damage by

blast and fire

blast only

Mitsubishi torpedo

factory

1.5Km

(5,000ft)

900m

(3,000ft)

300m

(1,000ft)

Shiroyama

Primary

School

Nagasaki Medical

College

GROUND

ZERO

Chinzeigakuin

High School

Nagasaki University

Hospital

Fuchi

School

Mitsubishi

steel and arms

factory

1.5Km

(5,000ft)

Isolation

Hospital

ZENZAMACHI

Mitsubishi

turbine factory

FUCHI SHRINE

2.1Km

(7,000ft)

NISHIZAKA

Governor’s

residence

Nagasaki

Station

2.7Km

(9,000ft)

Asami

School

KANAYAMACHI

Mitsubishi

Electronics

Mukoshima

substation

EDOMACHI

3.3Km

(11,000ft)

Nagasaki

Court

NAGASAKI

HARBOR

IWASEDOMACHI

3.9Km

(13,000ft)

OURAMACHI

Mitsubishi

Dock Yards

0

500m

The “Fat Man” bomb hit structures 5 km away because it’s detonation of about 500m from the ground increased the structural damage.

5.1km away

from the blast

(17,000ft)

NAGASAKI

On August 9, 1945, the B-29 “Bockscar” took off towards the city of Kokura. However, that day the city was covered by clouds, so Nagasaki was devastated instead.

0

500m

Structural damage by

blast and fire

Mitsubishi

torpedo factory

Structural damage by

blast only

1.5Km

(5,000ft)

Yamazato

Primary School

900m

(3,000ft)

300m

(1,000ft)

Shiroyama

Primary

School

GROUND

ZERO

Nagasaki Medical

College

Nagasaki

University

Hospital

900m

(3,000ft)

Chinzeigakuin

High School

Mitsubishi

Industrial School

Fuchi

School

Mitsubishi

steel and arms

factory

1.5Km

(5,000ft)

Isolation

Hospital

Zenza

primary school

ZENZAMACHI

Mitsubishi

turbine factory

FUCHI SHRINE

2.1Km

(7,000ft)

NISHIZAKA

Governor’s

residence

Nagasaki

Station

2.7Km

(9,000ft)

Asami

School

KANAYAMACHI

Mitsubishi

Electronics

Mukoshima

substation

EDOMACHI

3.3Km

(11,000ft)

Nagasaki

Court

NAGASAKI

HARBOR

IWASEDOMACHI

3.9Km

(13,000ft)

OURAMACHI

Mitsubishi

Dock Yards

Mitsubishi

Trading

The “Fat Man” bomb hit structures that were up to 5 km away since in the test phase, they discovered that detonation about 500 m from the ground would increase structural damage.

5.1km away

from the blast

(17,000ft)

NAGASAKI

On August 9, 1945, the B-29 “Bockscar” took off towards the city of Kokura. However, that day the city was covered by clouds, so Nagasaki was devastated instead.

0

500m

Structural damage by

Mitsubishi

torpedo factory

Urakami

power station

blast and fire

Structural damage by

blast only

1.5Km

(5,000ft)

Yamazato

Primary School

900m

(3,000ft)

300m

(1,000ft)

Shiroyama

Primary School

The “Fat Man” bomb hit structures that were up to 5 km away since in the test phase, they discovered that detonation about 500 m from the ground would increase structural damage.

GROUND ZERO

Nagasaki Medical

College

Chinzeigakuin

High School

Nagasaki

University

Hospital

900m

(3,000ft)

Keiho Boy’s

High School

Mitsubishi

Industrial School

Fuchi

School

Mitsubishi

steel and arms

factory

1.5Km

(5,000ft)

Isolation

Hospital

Zenza

primary school

ZENZAMACHI

Mitsubishi

turbine factory

FUCHI SHRINE

2.1Km

(7,000ft)

NISHIZAKA

Governor’s

residence

Asami

School

Nagasaki

Station

2.7Km

(9,000ft)

KANAYAMACHI

Mitsubishi

Electronics

Mukoshima

substation

EDOMACHI

Nagasaki

Court

3.3Km

(11,000ft)

NAGASAKI

HARBOR

IWASEDOMACHI

3.9Km

(13,000ft)

OURAMACHI

Mitsubishi

Dock Yards

Mitsubishi

Trading

4.5km away

from the blast

(15,000ft)

NAGASAKI

0

500m

On August 9, 1945, the B-29 “Bockscar” took off towards the city of Kokura. However, that day the city was covered by clouds, so Nagasaki was devastated instead.

Structural damage by

Urakami

power station

blast and fire

Mitsubishi

torpedo factory

Structural damage by

blast only

1.5Km

(5,000ft)

Yamazato

Primary School

900m

(3,000ft)

300m

(1,000ft)

Shiroyama

Primary School

The “Fat Man” bomb hit structures that were up to 5 km away since in the test phase, they discovered that detonation about 500 m from the ground would increase structural damage.

GROUND ZERO

300m

(1,000ft)

Nagasaki Medical

College

Chinzeigakuin

High School

Nagasaki University

Hospital

900m

(3,000ft)

Keiho Boy’s

High School

Mitsubishi

Industrial School

900m

(3,000ft)

Fuchi

School

Mitsubishi

steel and arms

factory

1.5Km

(5,000ft)

Isolation

Hospital

Zenza

primary school

ZENZAMACHI

Mitsubishi

turbine factory

FUCHI SHRINE

2.1Km

(7,000ft)

NISHIZAKA

Governor’s

residence

Asami

School

Nagasaki

Station

2.7Km

(9,000ft)

KANAYAMACHI

Katsuyama

primary school

Mitsubishi

Electronics

Mukoshima

substation

EDOMACHI

NAGASAKI

HARBOR

Nagasaki

Court

3.3Km

(11,000ft)

IWASEDOMACHI

3.9Km

(13,000ft)

OURAMACHI

Mitsubishi

Dock Yards

Mitsubishi

Trading

4.5km away

from the blast

(15,000ft)

NAGASAKI

0

500m

On August 9, 1945, the B-29 “Bockscar” took off towards the city of Kokura. However, that day the city was covered by clouds, so Nagasaki was devastated instead.

Structural damage by

1.5Km

(5,000ft)

Urakami

power station

Mitsubishi

torpedo factory

blast and fire

Structural damage by

blast only

1.5Km

(5,000ft)

Yamazato

Primary School

900m

(3,000ft)

300m

(1,000ft)

Shiroyama

Primary School

The “Fat Man” bomb hit structures that were up to 5 km away since in the test phase, they discovered that detonation about 500 m from the ground would increase structural damage.

GROUND ZERO

300m

(1,000ft)

Nagasaki Medical

College

Chinzeigakuin

High School

Nagasaki Univ.

Hospital

900m

(3,000ft)

Keiho Boy’s

High School

Mitsubishi

Industrial School

900m

(3,000ft)

1.5Km

(5,000ft)

Mitsubishi

steel and arms

factory

Fuchi

School

1.5Km

(5,000ft)

Isolation

Hospital

Zenza

primary school

ZENZAMACHI

Mitsubishi

turbine factory

2.1Km

(7,000ft)

FUCHI SHRINE

NISHIZAKA

2.1Km

(7,000ft)

Governor’s

residence

Asami

School

Nagasaki

Station

2.7Km

(9,000ft)

KANAYAMACHI

Katsuyama

primary school

Mitsubishi

Electronic Co.

Mukoshima

substation

EDOMACHI

NAGASAKI

HARBOR

Nagasaki Court

3.3Km

(11,000ft)

IWASEDOMACHI

3.9Km

(13,000ft)

OURAMACHI

Mitsubishi

Dock Yards

Mitsubishi

Trading

4.5km away

from the blast

(15,000ft)

Testing

Since World War II, no country has attacked another with a nuclear weapon. But at least eight have developed them, and as scientists theorised new designs – including the vastly more powerful fusion weapons, so-called “hydrogen bombs” - testing began all over the world. More than 2,000 nuclear weapons have been detonated in experiments since Oppenheimer watched the Trinity test fireball scour the New Mexico desert.

Nevada test site

The Sedan crater is the result of a 104-kiloton thermonuclear explosion in July 1962. The crater is located within the Nevada Test Site at Yucca Flat. It is 390 m (1,280 ft) wide and 100 m (328 ft) deep.

Sedan crater

390m diameter

Bomb test craters

Bomb test craters

YUCCA FLAT BASIN

U.S.

Nevada test site

Sedan crater

390m diameter

Bomb test craters

Bomb test craters

YUCCA FLAT BASIN

U.S.

Nevada test site

Sedan crater

390m diameter

Bomb test craters

YUCCA FLAT BASIN

Bomb test craters

U.S.

Nevada test site

Bomb test craters

Sedan crater

390m diameter

Bomb test craters

YUCCA FLAT BASIN

U.S.

Nevada test site

Bomb test craters

Sedan crater

390m diameter

Bomb test craters

YUCCA FLAT BASIN

U.S.

Nevada test site

Satellite image: Sentinel 2, European Space Agency. July 17, 2020.

For decades, many of these tests were atmospheric, meaning the weapons were detonated above ground, and sometimes even in space. Others were underground, detonated in vaults deep below the surface, meant to contain the blast and prevent fallout while instruments measured how well the new designs worked.

Nuclear explosions

The world’s two biggest nuclear powers, the United States and Russia, have not tested any nuclear weapons since 1992. Other countries trying to develop their own arsenals have carried out tests more recently.

EXPLOSIVE YIELD

Multiple

detonations

TNT equivalent

10,000Kt

Atmospheric tests

U.S.

were conducted until 1963, when the Limited Test Ban Treaty was signed.

TEST YEAR

LITTLE BOY

1945

Russia

(USSR)

1950

Others

1955

France

1960

UNCLE (1.2Kt)

China

TSAR BOMBA

(50,000Kt)

1965

1970

3,400Kt

1975

4,200Kt

1980

1,900Kt

1985

200Kt

1990

JUNCTION (200Kt)

1995

Underground

5Kt

testing first started with U.S. project code-named UNCLE in Yucca Flat desert.

SHAKTI-1 (45Kt)

2000

North Korea

2005

In 2017, North Korea showed off a device that exploded underground with a yield of about 100 kilotons –about six times more powerful than Little Boy.

2010

2015

2020

Multiple

detonations

EXPLOSIVE YIELD

TNT equivalent

10,000Kt

U.S.

TEST YEAR

1945

LITTLE BOY

Russia

(USSR)

Atmospheric tests

1950

were conducted until 1963, when the Limited Test Ban Treaty was signed.

Others

Underground

testing first started with U.S. project code-named UNCLE in Yucca Flat desert.

1955

France

1960

UNCLE (1.2Kt)

China

TSAR BOMBA

(50,000Kt)

1965

SIRIUS (200Kt)

CANOPUS (2,600Kt)

The Tsar Bomba yield was equivalent of 50 million tons of TNT. The fusion weapon created a fireball about five miles in diameter.

1970

3,400Kt

1975

4,200Kt

NESTOR (200Kt)

1980

1,900Kt

1985

GALATEE (200Kt)

1990

200Kt

JUNCTION (200Kt)

1995

5Kt

XOUTHOS (200Kt)

SHAKTI-1 (45Kt)

Xouthos, the last French bomb test, was detonated in the French Polynesia in Jan. 1996.

2000

North Korea

2005

North Korea, a state whose conventional military is aging and outclassed, has tested at least six nuclear weapons since 2006.

2010

2015

In 2017, North Korea showed off a device that exploded underground with a yield of about 100 kilotons –about six times more powerful than Little Boy.

2020

Multiple

detonations

EXPLOSIVE YIELD

TNT equivalent

U.S.

TEST YEAR

10,000Kt

1945

LITTLE BOY

Russia

(USSR)

Atmospheric tests

were conducted until 1963, when the Limited Test Ban Treaty was signed, eliminating nuclear weapons testing in the atmosphere, underwater or in outer space.

1950

Britain became the third nuclear power after Operation Hurricane.

Others

HURRICANE (25Kt)

1955

Underground

testing first started with U.S. project code-named UNCLE in Yucca Flat desert.

France

1960

UNCLE (1.2Kt)

China

TSAR BOMBA

(50,000Kt)

1965

SIRIUS (200Kt)

CANOPUS (2,600Kt)

BENHAM (1,150Kt)

The biggest nuclear device ever detonated, by far, was Tsar Bomba, whose yield was more than 50 megatons –the equivalent of 50 million tons of TNT.

1970

3,400Kt

1975

4,200Kt

BANON (200Kt)

NESTOR (200Kt)

1980

1,900Kt

TORTUGAS (200Kt)

1985

GALATEE (200Kt)

1990

200Kt

JUNCTION (200Kt)

1995

THEMISTI (200Kt)

5Kt

XOUTHOS (200Kt)

SHAKTI-1 (45Kt)

Xouthos, the last French bomb test, was detonated in the French Polynesia in Jan. 1996.

2000

The Chinese “Project 596” began testing in 1964. Its last detonation was carried out on July 29, 1996 at Lop Nor, a test facility in Xinjiang.

North Korea

2005

North Korea, a state whose conventional military is aging and outclassed, has tested at least six nuclear weapons since 2006.

2010

2015

In 2017, North Korea showed off a device that exploded underground with a yield of about 100 kilotons –about six times more powerful than Little Boy.

2020

EXPLOSIVE YIELD

U.S.

TEST YEAR

TNT equivalent

1945

LITTLE BOY

Multiple

detonations

10,000Kt

Britain became the third nuclear power after Operation Hurricane. The plutonium device was detonated on October 1952 in Monte Bello Islands in Western Australia.

Russia

(USSR)

1950

Others

Atmospheric tests

were conducted until 1963, when the Limited Test Ban Treaty was signed, eliminating nuclear weapons testing in the atmosphere, underwater or in outer space.

HURRICANE (25Kt)

1955

Underground

testing first started with U.S. project code-named UNCLE in Yucca Flat desert. This location saw more than 800 separate detonations.

France

1960

UNCLE (1.2Kt)

China

1965

TSAR BOMBA

(50,000Kt)

CANOPUS

(2,600Kt)

BENHAM

(1,150Kt)

The biggest nuclear device ever detonated, by far, was Tsar Bomba, whose yield was more than 50 megatons –the equivalent of 50 million tons of TNT. The fusion weapon created a fireball about five miles in diameter.

1970

3,400Kt

1975

BANON

(200Kt)

4,200Kt

NESTOR (200Kt)

1980

EGMONT

(200Kt)

1985

GALATEE (200Kt)

NIGHTINGALE

(200Kt)

200Kt

1990

JUNCTION

(200Kt)

THEMISTI (200Kt)

1995

5Kt

XOUTHOS (200Kt)

SHAKTI-1

(45Kt)

Xouthos, the last French bomb test, was detonated in the French Polynesia in Jan. 1996.

The Chinese “Project 596” began testing in 1964. Its last detonation was carried out on July 29, 1996 at Lop Nor, a test facility in Xinjiang.

2000

North Korea

2005

North Korea, a state whose conventional military is aging and outclassed, has tested at least six nuclear weapons since 2006.

2010

2015

In 2017, North Korea showed off a device that exploded underground with a yield of about 100 kilotons –about six times more powerful than Little Boy.

2020

U.S.

TEST YEAR

10,000Kt

1945

LITTLE BOY

EXPLOSIVE YIELD

TNT equivalent

Russia

(USSR)

Multiple

detonations

1950

Atmospheric tests

were conducted until 1963, when the Limited Test Ban Treaty was signed, eliminating nuclear weapons testing in the atmosphere, underwater or in outer space.

Others

Britain became the third nuclear power after Operation Hurricane. The plutonium device was detonated on October 1952 in Monte Bello Islands in Western Australia.

HURRICANE (25Kt)

TOTEM 2 (10Kt)

1955

Underground

testing first started with U.S. project code-named UNCLE in Yucca Flat desert. This location saw more than 800 separate detonations.

France

1960

UNCLE (1.2Kt)

China

1965

TSAR BOMBA

(50,000Kt)

SIRIUS

(200Kt)

CANOPUS

(2,600Kt)

BENHAM (1,150Kt)

The biggest nuclear device ever detonated, by far, was Tsar Bomba, whose yield was more than 50 megatons –the equivalent of 50 million tons of TNT. The fusion weapon created a fireball about five miles in diameter.

1970

3,400Kt

1975

4,200Kt

BANON (200Kt)

NESTOR

(200Kt)

1980

EGMONT

(200Kt)

TORTUGA

(200Kt)

1,900Kt

1985

GALATEE

(200Kt)

NIGHTINGALE

(200Kt)

200Kt

1990

JUNCTION

(200Kt)

THEMISTI (200Kt)

1995

5Kt

XOUTHOS (200Kt)

Xouthos, the last French bomb test, was detonated in the French Polynesia in Jan. 1996.

The Chinese “Project 596” began testing in 1964. Its last detonation was carried out on July 29, 1996 at Lop Nor, a test facility in Xinjiang.

SHAKTI-1 (45Kt)

2000

2005

North Korea

North Korea, a state whose conventional military is aging and outclassed, has tested at least six nuclear weapons since 2006.

2010

2015

In 2017, North Korea showed off a device that exploded underground with a yield of about 100 kilotons –about six times more powerful than Little Boy.

2020

“Nuclear technology is only getting easier,” said Melissa Hanham, deputy director of the Open Nuclear Network. “It’s not new tech anymore. Other countries and even non-state actors could choose to build covert nuclear programs.”

On the firing line

Testing has human consequences. Even when things went as planned, early atmospheric tests threw fallout into the atmosphere that could wind up hundreds of miles away or more.

When they went badly, the results could be catastrophic. America’s Castle Bravo test in 1954 was meant to evaluate the design of a 5 megaton weapon - the equivalent of 5 million tons of conventional high explosives. Instead, the device exploded with a yield of 15 megatons, vaporising many of the test instruments and throwing fallout high into the atmosphere. Several hours later, it blanketed a Japanese fishing vessel called the Daigo Fukuryū Maru. All of the 23 crew members suffered from radiation sickness, and one died.

Testing locations

Since 1945, more than 2,000 nuclear explosive tests have been carried out around the world.

U.S.

Soviet Union

Others

EXPLOSIVE YIELD

Megaton TNT

equivalent

10

1

Novaya Zemlya

Nevada

RUSSIA

U.S.

CHINA

Enewetak Atoll

Bikini

Atoll

U.S.

Soviet Union

Others

10

EXPLOSIVE YIELD

Megaton TNT

equivalent

1

Novaya Zemlya

Nevada

RUSSIA

U.S.

CHINA

ALGERIA

AUSTRALIA

Enewetak Atoll

Bikini Atoll

U.S.

Soviet Union

Others

10

5

EXPLOSIVE YIELD

Megaton TNT

equivalent

1

Novaya Zemlya

Nevada

RUSSIA

JAPAN

U.S.

CHINA

ALGERIA

Enewetak Atoll

AUSTRALIA

Bikini Atoll

10

U.S.

Soviet Union

Others

5

EXPLOSIVE YIELD

Megaton TNT

equivalent

1

Novaya Zemlya

Nevada

RUSSIA

JAPAN

U.S.

CHINA

ALGERIA

PACIFIC

OCEAN

Enewetak Atoll

ATLANTIC

OCEAN

AUSTRALIA

Bikini Atoll

U.S.

Soviet Union

Others

Novaya Zemlya

Nevada

RUSSIA

EXPLOSIVE YIELD

Megaton TNT equivalent

10

JAPAN

U.S.

5

CHINA

ALGERIA

1

Enewetak Atoll

PACIFIC

OCEAN

Bikini Atoll

ATLANTIC

OCEAN

INDIAN

OCEAN

AUSTRALIA

Hundreds of native people were moved from their homes on and around the South Pacific atolls where the United States did most of its atmospheric testing.

“Uranium mining, waste and testing are often done on indigenous land, and those performing the work and locals suffer health, environmental and economic damage.”

Melissa Hanham, deputy director of the Open Nuclear Network.

“Nearly everywhere in the world nuclear weapons are tested, indigenous people are affected disproportionately,” Hanham said.

Stockpiles

Seventy-five years after the atomic flash set fire to Hiroshima, thousands of nuclear weapons sit in arsenals around the world, ready to deploy by aircraft or missile. The Arms Control Association estimates that there are nearly 14,000 such weapons, and that the United States and Russia account for the most by far: 6,185 for the United States and 6,490 for Russia, although of these only a third or so could be immediately used in a war.

The number of such “deployed” nuclear weapons is limited by the New START treaty, which Russia and the United States ratified in 2011. At the height of the Cold War, the total number of warheads was several times greater.

World’s nuclear warhead stockpile

Treaties have lowered the number of nuclear warheads since the end of the Cold War.

START treaty between the U.S. and the USSR is signed in 1991

Global stockpile peaked at 64,099 in 1986

U.S. - Russia START II treaty is signed

GLOBAL TOTAL

SORT treaty is signed

1986: USSR peaked at 45,000

U.S.S.R.

U.S.

1967: U.S. stockpile peaked at 31,255

START treaty is signed by the U.S. and Russia

OTHERS

2005

1945

1965

1985

COLD WAR

START treaty between the U.S. and the USSR is signed in 1991

Global stockpile peaked at 64,099 in 1986

U.S. - Russia START II treaty is signed

GLOBAL TOTAL

1986: USSR peaked at 45,000

SORT treaty is signed

U.S.S.R.

New START treaty is signed by the U.S. and Russia, reducing the number of deployed nuclear weapons to 1,550 each side by 2017

U.S.

1967: U.S. stockpile peaked at 31,255

OTHERS

1955

1965

1975

1985

1995

2005

2015

1945

COLD WAR

START treaty between the U.S. and the USSR is signed in 1991

Global stockpile peaked at 64,099 in 1986

U.S. - Russia START II treaty is signed

GLOBAL TOTAL

1986: USSR peaked at 45,000

SORT treaty is signed

U.S.S.R.

U.S.

New START treaty is signed by the U.S. and Russia, reducing the number of deployed nuclear weapons to 1,550 each side by 2017

1967: U.S. stockpile peaked at 31,255

OTHERS

1955

1965

1975

1985

1995

2005

2015

1945

COLD WAR

START treaty between the U.S. and the USSR is signed in 1991

Global stockpile peaked at 64,099 in 1986

GLOBAL TOTAL

U.S. - Russia START II treaty is signed

1986: USSR peaked at 45,000

SORT treaty is signed

U.S.S.R.

New START treaty is signed by the U.S. and Russia, reducing the number of deployed nuclear weapons to 1,550 each side by 2017

U.S.

1967: U.S. stockpile peaked at 31,255

OTHERS

1945

1955

1965

1975

1985

1995

2005

2015

COLD WAR

The other states with nuclear weapons are Britain, China, France, India, Israel and Pakistan. South Africa developed nuclear weapons in the 1980s, but by the end of the decade decided to dismantle them. In 1994, the International Atomic Energy Agency confirmed all of the weapons had been destroyed.

The future

In 2018, Russia announced it had developed a nuclear-armed underwater autonomous vehicle dubbed Poseidon. The vehicle, Russian officials said, could quietly carry a nuclear warhead with a yield of tens of megatons to a point just offshore an enemy city.

The United States spends nearly $50 billion a year on its nuclear weapons. In 2020, media said the Trump administration was considering ways to restart testing.

Nuclear-armed neighbors China and India have seen border disputes escalate to bloodshed, and North Korea is building a nuclear-armed submarine.

Even so, 75 years have passed without a nuclear attack.

“I worry that people have become complacent and think that nuclear devastation only happens in black-and-white photographs,” said Jeffrey Lewis, head of the East Asia Nonproliferation Project at the Middlebury Institute of International Studies. “I am hopeful that we can stretch the streak for decades more - but the real question is whether nuclear deterrence will work forever. I am not so sure about that. And that means, sooner or later, our luck will run out.”

Sources:

Nuclear Explosion DataBase (NEDB).
Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization.
United States Strategic Bombing Survey, 1946.
Bulletin of the Atomic Scientists.
Sentinel-2, European Space Agency - ESA.
Reuters Research.
UNESCO.

By:

Simon Scarr, Marco Hernandez and Gerry Doyle

Editing by:

Clarence Fernandez