Three Mile Island accident falls under scale 5 nuclear power plant accidents. On March 28, 1979, in the wee hours of morning, the Three Mile Island nuclear generating station witnessed a nuclear meltdown of one secondary loop. This nuclear accident released 13 million curies of radioactive gases into the atmosphere. 10 court cases were filed on various authorities, concerning this accident, and took 15 years to get settled.

More than 240 people were exposed to radiation when a junkyard dealer in Goiania, Brazil, broke open an abandoned radiation therapy machine and removed a highly radioactive cake of cesium. The accident occurred on September 13, 1987. The environment and area were seriously contaminated. Many buildings had to be demolished. 4 died in this accident. Many children got attracted to the bright blue of the radioactive material, touched it and rubbed it on their skin, contaminating several blocks.

The accident took place on October 10, 1957 when a windscale fire ignited plutonium piles and contaminated surrounding dairy farms. The radioactive contamination caused 33 cancer deaths. This was the worst nuclear accident in Britain’s history, 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.

Chalk River Laboratory (CRL) is a site of major research and development to support and advance nuclear technology, in particular CANDU reactor technology. On December 12th, 1952, a reactor shutoff rod failure, combined with several operator errors, led to a major power excursion of more than double the reactor’s rated output at AECL’s NRX reactor. INES rated the incident as level 5.