10Worst Nuclear Accidents

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10 Worst Nuclear Disasters in History

Santosh Kumar II Sem M.Tech (ESM), SJCE, Mysore

110 Worst Nuclear Accidents/Disasters in History

1. Atomic Bombings of Hiroshima and Nagasaki World War II, 1945

These nuclear disasters were not accidents

but an ugly example of human wrath andviolence. It was a result of the war

between two big powers of the world.During the final stages of World War II in

1945, the United States conducted two

atomic bombings against the cities ofHiroshima and Nagasaki in Japan, the first

on August 6, 1945 and the second on

August 9, 1945. This nuclear disaster

caused innumerable deaths and seriousphysical, emotional and genetic problems

which were faced by many generations.Families were destroyed and people losttheir loved ones, home and money all in

one day. Within the first two to four

months of the bombings, the acute effectskilled 90,000166,000 people in

Hiroshima and 60,00080,000 in

Nagasaki.1520% died from radiation sickness, 2030% from flash burns, and 5060% from

other injuries, compounded by illness. Roughly half of the deaths in each city occurring on thefirst day. A study states that from 1950 to 2000, 46% of leukemia deaths and 11% of solid cancer

deaths among bomb survivors were due to radiation from the bombs. Even after such a huge

scale disaster and setback, the Japanese people faced this situation with courage and resolution

and made Japan one of the leading countries of the world.

2. Fukushima Disaster March 11, 2011

A massive 8.9 magnitude quake hit

northeast Japan on Friday March, 11

2011, causing dozens of deaths, morethan 80 fires, and a 10-meter (33-ft)

tsunami along parts of the countryscoastline. Homes were swept away and

damage was extensive. And the disaster

didnt end with this. Eleven reactors atfour sites near Japans northeast coastwere shut down per seismic emergency

procedures. Five reactors at two sites inthe Fukushima prefecture declared

emergencies due to loss of normal site

power and backup emergency power.According to a British nuclear expert the
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2explosion at the Fukushima I nuclear plant looks likely to be a significant nuclear event with a

bigger impact on public health than the 1979 meltdown at Three Mile Island. As of 15 March,the Finnish nuclear safety authority estimated the accidents at Fukushima to be at Level 6 on the

INES. On 24 March, a scientific consultant for Greenpeace, working with data from the

Austrian ZAMG and French IRSN, prepared an analysis in which he rated the total Fukushima I

accident at INES level 7. The accident caused nuclear contamination in the surroundingenvironment, water, milk, vegetable and other food items. People living in surroundings were

moved to safe shelters and food grown in the area was banned for sale. The Japanese government

in handling the situation in the most efficient and amazing way that anyone can imagine.Screening is being done and people are given proper medical care. Initially 3 workers were

affected by the radiation.

3. Chernobyl DisasterApril 26, 1986

The Chernobyl

disaster was a nuclearaccident that occurred

on 26 April 1986 at

the Chernobyl Nuclear

Power Plant in theUkrainian SSR (now

Ukraine). The

accident took place inthe reactor number 4

near the Pripyat town.

There was a sudden

power output surge,and when an

emergency shutdown

was attempted, a moreextreme spike in

power output occurred. This led to a reactor vessel rupture which caused a series of explosions.

Belarus, Russia, and Ukraine were seriously affected and about 60% of the fallout landed inBelarus. From 1986 to 2000, 350,400 people were evacuated and resettled from the most

severely contaminated areas of Belarus, Russia, and Ukraine. World Health Organization (WHO)

estimates the number of deaths to be 4,000 while a Greenpeace report puts this figure at 200,000

or more. Among these varied figures 31 deaths were confirmed to be caused by the accident. The

World Health Organization reported the radiation release from the Chernobyl accident to be 200times that of the Hiroshima and Nagasaki nuclear bombs combined. It is considered the most

serious nuclear power plant accident in history, and is the only accident classified as a level 7

event on the International Nuclear Event Scale.


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34. Mayak Nuclear PlantSeptember 29, 1957

Mayak Nuclear Plant, also known

as Chelyabinsk-40 and later as

Chelyabinsk-65 is one of thebiggest nuclear facilities in the

Russian Federation. It is anintegral part of the Russian nuclear

weapon program. The facility has

experienced 20 or more accidentsaffecting at least half a million

people in the past 45 years. The

most notable accident occurred on

29th September, 1957 exposing theSoviets Regiems secret. The failure

of the cooling system for a tankstoring tens of thousands of tons ofdissolved nuclear waste resulted in

a chemical (non-nuclear) explosion

having a force estimated at about 75 tons of TNT (310 gigajoules), which released some 2

million curies of radioactivity over 15,000 sq. miles affecting at least 200 people died ofradiation sickness, 10,000 people were evacuated from their homes, and 470,000 people were

exposed to radiation. Victims were seen with skin sloughing off their faces, hands and other

exposed parts of their bodies. A large area was left barren and unusable for decades and maybe

centuries. The accident caused a large number of fatalities, thousands were injured and

surrounding areas were evacuated. It is categorized as a level 6 serious accident on the 0-7

International Nuclear Events Scale.

5. Soviet Submarine K-431 AccidentAugust 10, 1985

The Echo II class Soviet

submarine K431 suffered amassive explosion during

refueling in Vladivostok,

Russia. The explosion produceda radioactive cloud of gas into

the air. Ten sailors were killed

in the incident and 49 peoplewere observed to have radiationinjuries with 10 developing

radiation sickness. Moreover of

the 2,000 involved in cleanupoperations, 290 were exposed

to high levels of radiation

compared to normal standards.


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46. Castle BravoMarch 1, 1954

Bikini Atoll,

Micronesian Islands inthe Pacific Ocean was

the site of more than 20nuclear weapons testsbetween 1946 and

1958. Castle Bravo

was the code namegiven to the first U.S.

test of a dry fuel

thermonuclear

hydrogen bomb. Thetest was performed on

March 1, 1954, at

Bikini Atoll, Marshall

Islands. When theweapon was detonated,

an explosion took

place, leaving a craterof 6,500 feet (2,000 m) in diameter and 250 feet (75 m) in depth. Castle Bravo was the most

powerful nuclear device ever detonated by the United States, with a yield of 15 Megatons which

was far exceeding the expected yield of 4-6 Megatons. This miscalculation led to a severeaccidental radiological contamination ever caused by the United States. In terms of TNT tonnage

equivalence, Castle Bravo was about 1,200 times more powerful than the atomic bombs which

were dropped on Hiroshima and Nagasaki during World War II. Moreover, the radiation cloud

contaminated more than seven thousand square miles of the surrounding Pacific Ocean,including small islands like Rongerik, Rongelap and Utirik. These islands were evacuated, but

generations to come where affected. Natives have since suffered from birth defects. A Japanese

fishing boat, Daigo Fukuryu Maru, also came into contact with the nuclear fallout, causingillness to all crew members with one fatality. Fish, water and land were seriously contaminated,

making Castle Bravo one of the worst nuclear accidents.


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57. Chalk River Nuclear AccidentDecember 12, 1952

Chalk River Laboratory (CRL)

is a site of major research anddevelopment to support and

advance nuclear technology, inparticular CANDU reactortechnology. On December 12th,

1952, a reactor shutoff rod

failure, combined with severaloperator errors, led to a major

power excursion of more than

double the reactors rated output

at AECLs NRX reactor. INESrated the incident as level 5. A

series of hydrogen gas

explosions hurled the four-ton

gasholder dome four feet through the air where it jammed in the superstructure. Thousands ofcuries of fission products were released into the atmosphere, and a million gallons of

radioactively contaminated water had to be pumped out of the basement and disposed of in

shallow trenches not far from the Ottawa River. The core of the NRX reactor could not bedecontaminated; it had to be buried as radioactive waste. Young Jimmy Carter, later U.S.

President, then a nuclear engineer in the U.S. Navy, was among the hundreds of Canadian and

American servicemen who were ordered to participate in the NRX cleanup following the

accident.

8. Windscale PileOctober 10, 1957

The accident took place on October10, 1957 when a windscale fire

ignited plutonium piles andcontaminated surrounding dairy

farms. The radioactive contamination

caused 33 cancer deaths. This was the

worst nuclear accident in Britainshistory, ranked in severity at level 5

on the 7-point International Nuclear

Event Scale. The fire released an

estimated 20,000 curies of iodine-

131, as well as 594 curies of caesium-137 and 24,000 curies of xenon-133,

among other radionuclides. Theincident produced around cancer

cases. In addition to this, milk farms

were seriously contaminated,

dropping milk sales by 15%.


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69. Goiania AccidentSeptember 13, 1987

More than 240 people were

exposed to radiation when ajunkyard dealer in Goiania,

Brazil, broke open anabandoned radiation therapymachine and removed a

small highly radioactive

cake of cesium chloride. Theaccident occurred on

September 13, 1987. The

environment and

surroundings were seriouslycontaminated. Many

buildings had to be

demolished. 4 died in this

accident. Many children gotattracted to the bright blue of the radioactive material, touched it and rubbed it on their skin,

resulting in the contamination of several city blocks.

10. Three Mile IslandMarch 28, 1979

Three Mile Island

accident (US 1979)falls under scale 5

nuclear power plantaccidents. On March 28,

1979, in the wee hours ofmorning, the Three Mile

Island nuclear generating

station witnessed anuclear meltdown of one

secondary loop. This

nuclear accident released13 million curies of

radioactive gases into the

atmosphere and caused aloss of USD 2,400. 10court cases were also

filed on various

authorities, concerningthis accident, and they took 15 long years to get settled. Fortunately it led to no deaths or

injuries.

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10Worst Nuclear Accidents