Severe health effects for a worker at a commercial irradiation facility as a result of high doses of radiation.Īn accident at a uranium processing plant in Tokaimura exposed 55 workers to radiation one died. to help in the emergency response.Īccident with Local Consequences: A minor release of radioactive material unlikely to result in implementation of planned countermeasures other than local food controls. Navy officer based in Schenectady, New York, was among those dispatched by the U.S. Former President Jimmy Carter, then a U.S.

A reactor shutoff rod failure, combined with several worker errors, led to a major power excursion of more than double the reactor’s rated output. The first-ever accident at a nuclear reactor.

It caused an estimated 200 cases of cancer in Britain. Radioactive dust was detected in Belgium, Germany and Norway. The Nuclear Regulatory Commission determined the accident “led to no deaths or injuries to plant workers or members of the nearby community.”Ī fire in a reactor core resulted in a limited off-site release of radioactivity. Doses off-site were less than normal background radiation. The incident forced the evacuation of over 10,000 people from the area contaminated by the blast.Īccident with Wider Consequences: A limited release of radioactive material likely to require implementation of some planned countermeasures and several deaths from radiation.įour people died and six received some doses of radiation from an abandoned highly radioactive medical teletherapy source that ruptured.Ī cooling malfunction caused part of the core to melt in a reactor, resulting in a limited off-site release of radioactivity over a multi-state area. Serious Accident: A significant release of radioactive material likely to require implementation of planned countermeasures.Īn explosion at a Soviet nuclear weapons plant in Kyshtym resulted in the release of “significant” radioactive material to the environment. By 2002, more than 4,000 thyroid cancer cases were diagnosed among people who were children at the time and ingested radioactive iodine, often through contaminated milk. More than five million people received low whole-body doses of radiation, about 1,000 emergency workers received the highest doses of radiation, some of them fatal. Nuclear Energy Agency reports there were 31 fatalities immediately following the incident, with latent deaths estimated at between 9,000 and 33,000 over the 70 years after, based on current radiation dose risks. There were widespread health and environmental effects. A significant fraction of the reactor core inventory was released, and contaminated areas of Belarus, Ukraine and the Russian Federation. Level 7 Major Accident: A major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures.Ī nuclear reactor located at a power plant in Chernobyl experienced a steam explosion and fire that caused a meltdown, releasing massive quantities of radioactive material. The INES scale, image by the International Atomic Energy Agency Learn more about the event scale below, and read about some of the worst nuclear disasters in history: The International Atomic Energy Agency uses the International Nuclear and Radiological Event Scale to assess the damage done by nuclear accidents. With three reactors having at least partial meltdowns at the Fukushima Daiichi power plant in Japan, the country raised the alert level from four to five on a seven-point international scale for atomic incidents Friday.

Nuke reactor meltdown