Sci-Tech

Top 10 Most Dangerous Nuclear Accidents Ever

Nuclear energy generated by 437 power plants located worldwide produce approx. 13% of the world’s electricity and 5.6% of the world’s energy. Despite the great contribution to the world’s energy needs, nuclear power plants come with the great risk of nuclear disasters. 

Faulty equipment, human errors and natural disasters traumatized the world on numerous occasions due to devastating outcomes of nuclear energy production. Below are the top dangerous nuclear accidents of all time.

#1 – Chernobyl Disaster

Chernobyl power pant disaster

The great popularity of the Chernobyl HBO show with an impressive IMDb rating of 9.6 has raised awareness into the top nuclear explosion. The Chernobyl nuclear disaster is one of the two, level 7 nuclear accidents in history.

Compilation of Rare Videos of Chernobyl Incident:- https://www.youtube.com/watch?v=Cc-vvhWXL9Q

The Chernobyl power plant, located in Pripyat, Ukraine met with its unfortunate faith causing 31 Chernobyl deaths within weeks. Long term deaths caused due to cancer and deformities due to extreme radiation is approx. 4000. The accident affected Ukraine, the Russian Federation and Belarus with 20,000 reported thyroid cancer patients below the age of 18. 




The Soviet RBMK design nuclear reactor which is different from a standard power plant’s identifies as the Chernobyl disaster cause. The absence of the containment structure in the RBMK nuclear reactor released radioactive substance to the environment. Inadequate safety precautions taken by the nuclear plant personnel also stand responsible. The work of 18 billion rubles and 500,000 workers controlled the catastrophic outcomes of the disaster.

The evacuation of the city took place 36 hours after the accident and remains a ghost city.

#2 – Fukushima Daiichi nuclear disaster

Fukushima Daiichi Nuclear Power Plant

The second top nuclear explosion in history to reach level 7 is the Fukushima Daiichi nuclear disaster. The tsunami and the Tōhoku earthquake in 2011 initiated the shutdown of the active reactors, hindering sustained fission reactions. Tsunami flooding the emergency units limited the coolant to decay heat. Thus, hydrogen-air explosions and 3 nuclear meltdowns struck Ōkuma, Fukushima Prefecture, Japan.

2019 Documentary by NHK World TV:- https://www.youtube.com/watch?v=sw0_VdEZemI

The NAICC declared that the plant operators didn’t take the required safety precautions to avoid the foreseeable nuclear blasts. Radiation exposure caused 1 death. Hydrogen explosions accounted for 16 individuals physically injured and 2 workers suffered from radiation burns.

The residents of the area showed a faint exposure to radiation. Thus, health complications due to radiation exposure are low.

#3 – Kyshtym disaster at Mayak Chemical Combine (MCC)

Kyshtym disaster at Mayak Chemical Combine

This accident occurred in 1957 at a weapon production site using nuclear technology in Mayak. Kyshtym disaster belongs to highly dangerous nuclear accidents as it reached level 6 on the INES. Evacuation procedures cleared the area of 10,000 residents. Unfortunately, at least 22 residents dealt with radiation exposure. The evacuation procedure took more than 2 years for completion.




As a result of these blasts, hot particles blew out to a coverage of 52,000 square kilometers affecting at least 270,000 residents.

#4 – Windscale

windscale nuclear accident

The Windscale fire in 1957 is another one of the tragic nuclear disasters measuring level 5 on the INES. The fire burned in the Windscale facility in Sellafield, Cumbria, England for 3 days. The British developed the graphite moderators as an atomic bomb project after the war. The radioactive materials swept through the UK and Europe.

The most common cause of thyroid cancer in nuclear disasters, radioactive isotope iodine-131 was present at Windscale accident. Leading to 240 reported cancer cases. Residents were not evacuated from the area.

#5 – Three Mile Island accident (TMI-2)

Three Mile Island accident

Another one of the nuclear disasters estimating level 5, is the Three Mile Island accident. The radiation leak occurred in 1979 in Dauphin Country, Pennsylvania. TMI-2 was the largest commercial nuclear power plant in the US.

Mechanical failures led to the disastrous outcomes of the accident. Inadequate training of personnel and other human errors were also highlighted. Radioactive materials released to the air with the opening of the pilot operated relief valve. This accident resulted in only low-level contaminations. Authorities instructed residents of the area to stay indoors.

#6 – First Chalk River accident

First Chalk River accident 1952

Chalk River Laboratories in Canada focused on the advancement and development of nuclear energy. Two nuclear blasts took place in 1952 and 1958. The shutting down of the NRX reactor triggered the first accident. Followed by errors made by personnel to control the situation. 




The second blast occurred in 1958 due to an overheated NRU reactor rupturing the reactor core. The burning of nuclear fuel released deadly products throughout the building. 600 men took part in cleaning the NRU. Authorities reported no adverse health effects of the nuclear accident.

#7 – Goiânia accident

Goiânia accident 1987

The Goiânia accident occurred in 1987 in Goiânia, Brazil. The reason behind the accident was the theft of a radiotherapy source from a deserted hospital. The accident resulted in 4 deaths. The authorities tested 112,000 individuals for radiation exposure. Out of which, 249 individuals showed levels of contamination.

The Goiânia accident, one of the world’s worst nuclear accidents, according to Time magazine. The cleanup procedure included demolition of houses, buildings and elimination of topsoil. The owners of the hospital, 3 doctors were given charges of criminal negligence.

#8 – Sellafield (United Kingdom)

sellafield nuclear accident

The UK’s worst nuclear accident happened in 1957, in a plutonium production and nuclear reactor facility. The fire burnt for 16 hours causing the release of radioactive material into the atmosphere. 

The radiation affected milk in an area covering 500 square kilometers. So, the government banned the use of milk in this area. The British government was reluctant on releasing the true magnitude of the accident. The Windscale nuclear reactor closed down in 1980 for cleanup, expected to be finished in 2015.

#9 – SL-1 Experimental Power Station

sl-1 experimental power station

In 1961, the US army’s SL-1 experimental power station dealt with the shocking outcomes of a steam explosion followed by a meltdown. The purpose of the power station was to provide power and heat for military facilities. Another one of the worst nuclear disasters killed 4 of the operators. This is the only nuclear accident in US history to have onsite fatalities. Inadequate withdrawal steps taken to the central control rod caused the reactor core to absorb neutrons. 

#10 – Saint-Laurent Nuclear Power Plant

Saint-Laurent Nuclear Power Plant

Located in Saint-Laurent-Nouan, the Saint-Laurent power plant accident is the worst faced by France. A failure in the cooling system of the power plant in 1980 led to a meltdown in a fuel channel. The accident estimated level 4 in the INES. Fortunately, no radioactive materials escaped to the outside. Prior to the accident in 1980, the first nuclear accident at Saint-Laurent Nuclear Power Plant struck in 1969.

Further information about the accident was not released to the public by the Inspector General for Nuclear Safety and Protection, Andrá Gauvenet.

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Nicole Watson

Nicole Watson

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