Top 10 Nuclear Disasters

Top 10 Nuclear Disasters


The long term effects of Nuclear disasters can often spread over thousands of years. It is estimated that Chernobyl wont be inhabited for at least another 20,000 years.

Despite the threat of  Nuclear disasters, believe it or not, Nuclear Power Plants are prominent and provide approximately 5.7% of the world’s energy and 13% of the world’s electricity.

With 437 Nuclear Power Plants worldwide, there are bound to be incidents every now and again. Small incidents occur and can be rectified, but when there are large incidents, the impact can often be catastrophic.

Each Nuclear disaster has been given a level on the International Nuclear Event Scale (INES).

Click on the header of each nuclear disaster for a detailed look at each event.

Process Industry Forum have scrawled the web and created a Top 10 for the worst Nuclear disasters of all time:


10. Tokaimura, Japan 1999 – Level 4

When a group of unqualified workers decided to put more highly enriched uranium in a precipitation tank than was permitted, disaster struck. Two of the workers eventually died with another fifty six plant workers also being exposed to high levels of radiation. To make matters worse, 21 civilians were also exposed to high doses of radiation and residents within a thousand feet of the plant were evacuated.


9. Buenos Aires, Argentina 1983 – Level 4

An operator’s errors during a fuel plate reconfiguration lead to him dying two days later. There was an excursion of 3×10 fissions at the RA-2 facility with the operator absorbing 2000 rad of gamma and 1700 rad of neutron radiation. Another 17 people outside of the reactor room absorbed doses ranging from 35 rad to less than 1 rad.


8. Saint- Laurent, France 1969 – Level 4

On the 17th October, 1969 50 kg of uranium in one of the gas cooled reactors began to melt. This was classified as Level 4 on the INES and to this day remains the most serious civil Nuclear disaster in French history.


7. SL-1 Experimental Power Station, Idaho USA 1961 – Level 4

On 3rd January, 1961 a USA army experimental nuclear power reactor underwent a steam explosion and meltdown killing its three operators. The cause of this was because of improper removal of the control rod, responsible for absorbing neutrons in the reactor core. This event is the only known fatal reactor accident in the USA. The accident released about 80 curies of iodine -131.


6. Goiania Accident, Brazil 1987 – Level 5

On 13th September, 1987 a radioactive contamination accident occurred in the Brazilian state of Goais. An old radiotherapy source was stolen from an abandoned hospital site in the city. Subsequently it was handled by many people, killing four people. 112,000 people were examined for radioactive contamination’s with 249 having significant levels of radioactive material in or on their body.


5. Three Mile Island Accident, Pennsylvania USA 1979 – Level 5

28th March saw two nuclear reactors meltdown. It was subsequently the worst disaster in commercial nuclear power plant history. Small amounts of radioactive gases and radioactive iodine were released into the environment. Luckily, epidemiology studies have not linked a single cancer with the accident.


4. Windscale Fire (Sellafield), UK 1957 – Level 5

The worst nuclear disaster in Great Britain’s history occurred on the 10th October, 1957 and ranked at level 5 on the INES scale, The Windscale Fire. The two piles had been hurriedly built as part of the British atomic bomb project. The first pile was active from October 1950 with the second close behind in June 1951. The accident occurred when the core of Unit 1’s reactor caught fire, releasing substantial amounts of radioactive contamination into the surrounding area. 240 cancer cases have since been linked to the fire. All of the milk from within about 500km of nearby countryside was diluted and destroyed for about a month.


3. Kyshtym, Russia 1957 – Level 6

The Kyshtym Nuclear disaster was a radiation contamination incident that occurred on 29 September 1957 at Mayak, a Nuclear fuel reprocessing plant in the Soviet Union. It measured as a Level 6 disaster on the INES, making it the third most serious Nuclear disaster ever recorded behind the Chernobyl Disaster and Fukushima Daiichi Disaster. The event occurred in the town of Ozyorsk, a closed city built around the Mayak plant. Since Ozyorsk/Mayak was not marked on maps, the disaster was named after Kyshtym, the nearest known town.


2. Fukushima, Japan 2011 – Level 7

The Fukushima Daiichi nuclear disaster was a series of equipment failures, nuclear meltdowns and releases of radioactive materials at the Fukushima, Nuclear Power Plant, following the Tohoku Tsunami on 11 March, 2011.  It is the largest nuclear disaster since the Chernobyl disaster of 1986 and only the second disaster (along with Chernobyl) to measure Level 7 on the INES.


1. Chernobyl, Ukraine 1986 – Level 7

The Chernobyl Nuclear disaster is widely considered to have been the worst power plant accident in history, and is one of only two classified as a level 7 event on the International Nuclear Event Scale (the other being the Fukushima, Daiichi disaster in 2011). The battle to contain the contamination and avert a greater catastrophe ultimately involved over 500,000 workers and cost an estimated 18 billion rubles.  The official Soviet casualty count of 31 deaths has been disputed and long-term effects such as cancers and deformities are still being accounted for.




Alex Wall

Engineering & Manufacturing Blogger & Writer.

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  • jared

    cool page

  • jared

    nice page

  • jared

    hi jake

  • bledi

    Thanks very much. It helped me alot.

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  • monterino

    You forgot 2 incidents that were level 10: They occurred in the cities of Hiroshima and Nagasaki.

    • Alex Stull

      I know your being a smarta## but the scale goes to 7knucklehead

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  • russp

    If you add up all the deaths that resulted or will result from all of these nuclear “disasters” combined (excluding Chernobyl), it will be less than the number of deaths that occur EVERY SINGLE DAY from coal-fired power. Stop falling for this ridiculous lack of perspective when it comes to nuclear power.

    • Daniel B.

      What about the sections of our planet that become useless for thousands of years after these disasters occur? Does coal do that as well?

      • russp

        Coal fouls land at a far, far higher rate than nuclear. When the world burns 250 tons of coal per *second*, where do you thing the ash all goes? Please read the set of slides that I put together at

  • Dr. A. Cannara

    Amazing how some folks personally benefitting from science and democracies committed to fact, pump out misinformation as well as the Kochs, when they’re ignorant of, yet biased against, something for personal pique or profit.

    was an excursion of 3×10 fissions at the RA-2 facility – See more at: Argentinian example reveals the writer’s malicious ignorance: “excursion of 3 x10 fissions”

    There were 30 fissions? There were actually a gazillion fissions.

    But, as the writer tries to hide, none of these, except Three Mile Island, were commercial, regulated, nuclear accidents. And in TMI. no one was hurt. No containment breached, etc.

    The event led to establishment of industry co-operation on training & safety procedures, and WANO, and all that raised the uptime of nuclear plants from ~65% to today’s ~90%. Think of all the coal plant obviated by that — thank you TMI!

    Anyone, using Fukushima or Chernobyl against nuclear power is just fibbing. Chernobyl’s RBMK reactors were/are illegal everywhere outside the Soviet Union. They were known to be unstable and were simply intended for making weapons Plutonium. Anyone, like this author, listing Chernobyl as equal to a western, nuclear accident is simply ignorant and/or lying. If someone want facts, go to knowledgeable, honest writers like Mahaffey and his “Atomic Accidents”.

    The other way this author demonstrates his untrustworthiness is by omitting basic facts, such as that the SL-1 accident was at a small Army reactor manned by a poorly trained individual. It was in no way a part of commercial nuclear power.

    Then we have Fukushima. Why does this author not explain that despite the greatest quake recorded in Japan, all Fukushima reactors shut down properly and were cooling properly until after the tsunami arrived? Remember, TEPCO had about 17 reactors in the region, yet could only ruin 3. And why does this author hide the reality of Fukishima Dai-Ini and Onagawa? Those all properly reached safe shutdown and Onagawa actually housed hundreds of tsunami refugees…

    The ~18,000 dead and billions in property losses weren’t due to nuclear power. They were due to something simple: poor govt. land-use policy in a known tsunami zone. Why no discussion of the largest tragedy wrought by the Japanese own govt? Doesn’t have the scare mongering value of nuclear?

    Why no mention of Onagawa, TEPCO corruption and govt. collusion here? Too inconvenient a truth? This piece is modelled on the same ploys climate deniers use — avoidance of facts.

    But, at least we now know this forum can’t be trusted. As Mark Twain said: “A lie gets half way around the world before the truth can get its boots on”. The fibbery here has gone around several times.

    Shame, The graphic shows the facts of nuclear power safety, even including the accidents mentioned above. This author apparently likes coal diseases & deaths, oil-transport destruction, gas explosions, wind workers’ deaths, etc. Shame.

    Dr. A. Cannara
    650 400 3071

  • Tim Johnston

    Fukushima measures 7, but the toll might be much larger than Chernobyl, when all is said and done.