First, the humans discovered fire and after that, they set out on a journey to form civilization and discover more efficient and powerful methods of generating energy. One of the most common sources for us has been fossil fuels, essentially pushing the world into the great industrial revolution. The biggest problem with fossil fuels, however, is that there isn’t an unlimited supply of them and the planet is bound to run out of these at some point. To tackle this issue, people started looking at alternative sources of energy and viola, we had nuclear energy.

Yes, this is the same nuclear energy that is used to build atomic bombs the likes of which were dropped on Hiroshima and Nagasaki, resulting in the deaths of millions of people which proved just how powerful it really was. If it could cause destruction then surely it could also be used for peaceful purposes. This still did not eliminate the risk though, as multiple nuclear disasters throughout history have continued to prove. Such accidents can involve both financial losses and damage to life. In this list, we have put together 15 of the worst nuclear disasters, most of which serve as a harrowing reminder of what we’re actually dealing with here.

15. Criticality Accident At Tokaimura, 1999

The nuclear facility at Tokai, Ibaraki has seen two major accidents over the course of its operations. One of these was an explosion which occurred in 1997 while the other one was a serious criticality accident in a JCO plant. The latter is the one that most people are usually of out of the two. At the time, it was the worst nuclear radiation accident to have occurred in Japan.

The accident took place at a uranium reprocessing facility where three of the workers were preparing a small batch of fuel for an experimental fast breeder reactor. One of the precipitation tanks reached critical mass during the process, resulting in the deaths of two workers. It was later found out that the workers who had been assigned to the job lacked a proper qualification or training, something that proved to be a contributing factor in the accident.

14. Explosion In Tomsk-7 Facility, 1993

Tomsk-7 was a secret city in Siberia and home to several nuclear facilities which were being used for the large-scale production of uranium for fuel and weapons. One of the worst nuclear disasters in Russian history occurred when workers at one of the facilities were trying to separate plutonium from spent nuclear fuel using nitric acid. The exact cause of the error is unknown but it is speculated that a lack of compressed air caused the radioactive mixture to reach critical temperatures.

The resulting explosion was so strong that it knocked down the walls on two floors and dispersed large amounts of radiation over an area of 120 square kilometers. It ended up exposing tens of thousands of people to large doses of radiation and seriously contaminated the natural elements for years to come.

13. K-431 Submarine Reactor Explosion, 1985

One of the more revolutionary applications of nuclear fuel has been aboard submarines. The benefit to using a nuclear reactor on one of these is that they do not require refueling and can stay submerged for longer periods of time, only resurfacing when the crew requires food. While there are a lot of benefits to this technology, it also comes with a huge set of drawbacks. A notable example of this was the Soviet K-431 submarine which suffered a reactor explosion while refueling at Chazhma Bay, Vladivostok.

This disaster ended in the deaths of ten naval personnel while more than 50 people suffered radiation injuries. It was identified as one of the worst nuclear disasters in the world and prompted a cleanup operation in which 2,000 people participated, exposing an additional 290 people to high levels of radiation.

12. Nuclear Meltdown At Three Mile Island, 1979

Though there are many nuclear disasters that happened throughout Russia, formerly the Soviet Union, the biggest cause behind of these were sub par constructions and procedures. The United States, on the other hand, had much higher safety standards but unfortunately even this wasn’t enough to avoid disaster. In 1979, a nuclear meltdown occurred in reactor number 2 of the Three Mile Island Nuclear Station.

The events of the accident unfolded as multiple failures occurred in the secondary system of the reactor, leading to a stuck-open relief valve in the primary system. This resulted in the release of a considerable amount of nuclear reactor coolant. This was one of the most significant nuclear accident in U.S history and was rated a five out of seven on the International Nuclear Event Scale. The financial costs in the aftermath of this disaster were quite high as well, with the government having to spend about $1 billion in cleanup operations.

11. Safety Cap Failure During Yucca Flat Test, 1970

The United States performed a number of nuclear tests throughout the time period of the Cold War when tensions were at an all-time high with the Soviet Union. Different test regions were allocated throughout the Nevada Test Site for these experiments and one the major sites was the Yucca Flat. A grand total of 739 nuclear tests were carried out here making it the most irradiated spot on the face of the Earth.

It should come as no surprise then that it was also the site for one of the worst nuclear disasters to occur in the history of the U.S. During a test of the Baneberry 10 kiloton device which was detonated 270 meters below the surface, a fissure near ground zero caused a failure of the shaft and cap. This allowed a plume of fire and radioactive debris to be released, raining fallout on the workers nearby. It resulted in 86 people being exposed to radiation out of which two died in 1974 due to acute myeloid leukemia.

10. Crash Of A B-52 With Nuclear Payload, 1968

Reactor accidents aren’t the only way through which a nuclear disaster can occur. Some of them can also happen due to improper handling of nuclear weapons or accidents involving the vehicles that carry these. In 1968, the Thule accident which is also known as the Thule Affair resulted in the crash of a B-52 bomber which had four hydrogen bombs on board. A cabin fire forced the crew to eject out of the aircraft before a successful emergency landing could be made at Thule Air Base.

The crash ended in the detonation of the conventional explosives, allowing the nuclear payload to rupture and dispersing radioactive material everywhere. One of the crew members was also killed and this accident marked the end of the USAF “Chrome Dome” operations.

9. Mid-Air Collision Of Nuclear Bomber, 1966

It is no wonder that the “Chrome Dome” operation was scrapped since there were 5 separate accidents that involved a B-52 carrying a nuclear payload. Two years before the Thule accident, the Palomares incident occurred when a USAF B-52G collided with a KC-135 tanker during mid-flight refueling procedures. This accident caused the deaths of all four crew aboard the KC-135 while three of the seven crew members of the B-52G perished.

The non-nuclear explosives in the Mk28-type hydrogen bombs detonated upon impact, allowing radioactive plutonium to be dispersed over an area of 2 square kilometers. A massive search operation to find one of the missing bombs was launched which was ended only when the device was finally recovered two and a half months later.

8. Fire At The Windscale Nuclear Facility, 1957

It seems as if even the Great Britain was not spared from the wrath of nuclear contamination. On October 10, 1957, a fire broke out in the graphite core of Unit 1 which was part of the two-pile Windscale nuclear facility in Cumberland, England. These reactors had been designed for the production of plutonium based weapons which are more powerful than conventional nuclear weapons.

The fire was finally put out after three days but not before it had resulted in the release of radioactive materials, more specifically iodine-131 which can cause thyroid cancer. While there were no immediate deaths, it is expected that the accident caused almost 240 cases of cancer and milk, which was expected to be contaminated in nearby countryside areas was diluted and destroyed for almost a month.

7. Explosion Of The SL-1 Due To Meltdown, 1961

The SL-1, short for Stationary Low-Power Reactor was an experimental nuclear reactor being operated by the United States Army which was the site of a nuclear accident in 1961. The is the only disaster in the nuclear history of the U.S in which there were immediate fatalities, with three of the operators being killed during a meltdown of the reactor which resulted in an explosion.

The cause of the accident was determined to be the improper withdrawal of one of the control rods that are usually responsible for absorbing neutrons in the reactor core. This incident prompted the designs of these reactors to be abandoned and future ones to include fail safe methods which would prevent such a disaster from happening again.

6. Chemical Accident At Marcoule Nuclear Site, 2011

Marcoule is one of the oldest nuclear sites in France which was opened back in 1955. The country is highly dependent on nuclear power, producing almost 75% of its energy needs using this method. In 2011, an accident occurred at the nuclear plant which resulted in the death of one person while seriously injuring four others.

The cause of the accident could not be determined, but the risk of a radioactive leak was quite minimal after the blast. France has spent a lot of money in recent years to develop nuclear systems which are safe and it is because of these measures that a disaster such as this was contained without significant damage.

5. Leaked Radiation On Board The K-27 Submarine, 1968

At the height of the Cold War, while the U.S was deploying operations such as the “Chrome Dome”, the Soviet Union was also using similar tactics which involved nuclear-powered submarines. One of these was the K-27 which met an unfortunate fate in 1968 when one of its reactors started leaking radiation during a mission in the Arctic.

The crew was unaware of this and only found out about it when they turned on one of their radiation detectors. A few hours later, some of the crew members started falling sick, unable to walk meaning they had to be carried. Out of the original 144 crew, only 56 are still alive today and it is unknown how much radiation each one was exposed to. The submarine was purposefully sunk in 1981 at a depth of just 30 meters in the Kara Sea.

4. Storage Tank Failure At Mayak, 1957

The Mayak Production Association was one of the biggest nuclear facilities inside Russia that continue to operate even to this day. It was originally constructed in utmost secrecy for the production of the first Soviet Union atomic bomb. Unfortunately, it also became the site of one of the most dangerous nuclear disasters to occur throughout history.

In 1957, a storage tank containing highly radioactive waste exploded, releasing all sorts of radioactive material into the atmosphere and contaminating an area of more than 750 square kilometers. This came to be known as the Kyshtym Disaster and it was kept by the Soviet regime as a secret for more than thirty years, eventually being rated a 6 out of 7 on the INES scale, just behind the Fukushima and Chernobyl disasters.

3. Stolen Radioactive Material Causes Goiania Accident, 1987

The Goiania Accident is one of those incidents in history which were caused by gross human negligence. It occurred in Goiania which is a city in the Golas state of Brazil. A junkyard dealer decided to take apart an abandoned radiotherapy machine, removing the highly radioactive cake of cesium chloride within. It was sold to numerous people before it was finally discovered that the item they had been handling was radioactive.

Children who were attracted to the blue light emanating from the material played around with it and rubbed it on their skin. A total of 249 people were discovered to have high levels of radioactive material on their bodies while four others had died because of direct radiation poisoning. Several city blocks had to be destroyed and topsoil from many different locations had to be removed in a cleanup operation that followed this horrific incident.

2. Tsunami Shuts Down Fukushima Daichi, 2011

A lot of you might be aware of this one since the Fukushima incident received a lot of coverage in the news and other media sources after the Japan earthquake and tsunami of 2011. The active reactors in the nuclear plant had automatically shut down immediately after the earthquake, however, cooling systems are still required to keep the temperature of the reactors down even after they stop working.

This is done using the emergency generators but those were rendered useless because of the Tsunami that followed right after the earthquake. This resulted in the nuclear meltdown of three units, causing hydrogen-air explosions and dispersing radioactive material in the surrounding areas. The Fukushima incident was one of the most significant nuclear disasters to occur after the 1986 disaster of Chernobyl.

1. Explosion in Reactor 4 At Chernobyl, 1986

This was the worst nuclear disaster to ever occur since the discovery of nuclear power. Ask anyone to list names of the most irradiated places on this Earth and they will definitely have Chernobyl on the top of that list. On the fateful morning of April 26, 1986, a safety test of reactor No. 4 was conducted which went horribly wrong and resulted in an explosion which dispersed 400 times more fallout than the bombing of Hiroshima.

It has been categorized as the most disastrous nuclear accidents in terms of both cost and casualties. Almost 134 people were hospitalized immediately after the event, out of which 28 died due to radiation sickness. The cleanup operations that followed are believed to one of the biggest in history involving over 500,000 workers who put their life on risk to work in highly radioactive environments. The people living in Chernobyl had to be evacuated and all that remains now are abandoned buildings and belongings which were left behind in haste.