On March 28, 1979, the Three Mile Island Unit 2 (TMI-2) reactor, which is located close to Middletown, Pennsylvania, experienced a partial meltdown. The most catastrophic accident in the history of nuclear power plants in the United States was brought on by the failure of a relief valve, which occurred following an unscheduled shutdown and resulted in extensive damage to the core. Things could have been substantially improved with stronger instrumentation, training programs, and public disclosure, but fortunately, no one was hurt and there were no obvious negative health effects.
On October 10, 1957, a blazing fire tore through the core of Unit 1 of the nuclear reactor that was located at Windscale, Cumberland (which is now known as Sellafield, Cumbria). The fire lasted for three days. Radioactive contamination was spread over Europe as a result of the Level 5 catastrophe, and it is believed that traces of the isotope iodine-131 may be responsible for several hundred newly diagnosed cases of cancer. During the construction of the British atomic bomb, the two piles that make up Windscale were rapidly constructed. It was the most serious nuclear accident that had ever occurred in the UK.
The clandestine Mayak plant, which was located close to the Russian town of Kyshtym and was a part of the Soviet Union's endeavor to compete with the United States in terms of weapons-grade plutonium production, was the site of the third most severe nuclear disaster in history. The failure to properly maintain a malfunctioning cooling system led to temperatures that eventually reached a point where an explosion occurred with the force of between seventy and one hundred tons of TNT. Nuclear fallout traveled more than 500 kilometers distant, and due to the secretive nature of the plant, it wasn't until a week later that 10,000 inhabitants were forced to flee the area and seek shelter elsewhere.
The Great East Japan Earthquake, which occurred on March 11, 2011, reached 9.0 on the Richter scale and was followed by a tsunami that measured 15 meters in height. This caused the power supply to be disrupted, which led to three reactor meltdowns at the Fukushima Daiichi plant. According to the statistics provided by the relevant authorities, the procedure of evacuating more than 100,000 people resulted in the deaths of more than one thousand individuals. Investigations that were conducted after the fact have revealed that the infrastructure and the risk assessment were not appropriate for a natural disaster of such catastrophic proportions. In all of recorded history, this was only the second accident to ever obtain the highest possible Level 7 rating.
The accident at the Chernobyl nuclear power plant was the worst and most expensive nuclear power plant accident that had ever occurred. The only other catastrophe of this severity occurred on April 26, 1986, when a steam explosion at the Ukrainian plant's reactor number four caused the reactor to be destroyed. As a direct consequence of these fires, huge quantities of radioactive waste were dispersed across Western Europe. As a direct consequence of this, approximately thirty people succumbed to acute radiation poisoning in the immediate aftermath, which raised long-term concerns about an increase in the incidence of thyroid cancer. It has been said by the World Nuclear Association that...
`The nuclear tragedy was the result of a defective Soviet reactor design in addition to major blunders committed by the operators of the plant`