Previous nuclear incidents and accidents

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Fukushima Daiichi

On March 11, 2011, an earthquake caused a tsunami that killed over 20,000 people and triggered a severe nuclear accident at the Fukushima Daiichi Nuclear Power Plant in Japan. This resulted in the release of radioactive material into the environment, prompting local evacuations and public health and safety measures globally as low levels of radioactive contaminants were detected worldwide.

In response to the Fukushima Daiichi accident, many Canadian federal departments activated their emergency plans and emergency operations centres. As the lead department of the Federal Nuclear Emergency Plan, Health Canada convened the multi-departmental Technical Assessment Group to provide coordinated situational assessment to the government response.

Extensive radiological monitoring was conducted in Canada as part of Canada's radiation surveillance programs. The impact on Canada was assessed in detail. The results are reported in the Special Environmental Radiation in Canada Report on Fukushima Accident Contaminants and summarised in the Summary Report on Fukushima Contaminants in Canada. The incremental radiation exposure from the accident was determined to be similar in populations throughout Canada and far less than exposure from natural background radiation.

In order to monitor the potential long-term impact of the event on Canada, the Government of Canada became a partner in the Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) network to monitor radiation levels off the coast of British Columbia. Data confirmed that the quantities of radioactive materials that reached Canada were very small and did not pose any human or environmental health risks.


On April 26, 1986, there was an accident at the Chernobyl nuclear power plant in Chernobyl, Ukraine (at the time, a part of the Soviet Union). This was the most severe accident in the history of the nuclear power industry. Due to the severity of the accident, 160,000 Ukrainian residents were evacuated and permanently relocated.

Radioactive material from the Chernobyl accident was found in neighbouring countries and parts of Western Europe, demonstrating for the first time that nuclear accidents can have international implications. This prompted the need for international cooperation, communication and transboundary requirements in national emergency plans.

After Chernobyl the International Atomic Energy Agency (IAEA) developed international conventions (Convention on Early Notification of a Nuclear Accident; Convention on Assistance in the Case of a Nuclear Accident or Radiological Emergency). Canada is a signatory to these conventions.

Other nuclear incidents

1952 and 1958, Chalk River

On December 12, 1952, the National Research Experimental (NRX) Reactor at Chalk River Laboratories in Ontario, Canada, experienced mechanical problems and operator error that led to overheating fuel rods and significant damage to the NRX reactor core. It was the world's first nuclear reactor accident.

On May 23, 1958, a fuel rod rupture in the National Research Universal (NRU) reactor led to a fire and contamination of the NRU building and surrounding area.

In both instances, the Canadian military helped with cleaning up.

1978, COSMOS 954

On January 24, 1978, COSMOS 954, a soviet nuclear-powered surveillance satellite crashed in the Northwest Territories, Canada. Covering land from Yellowknife's Great Slave Lake to northern Alberta and Saskatchewan with scattered debris. At the time, no single federal department was responsible for responding to such an event.

1979, Three Mile Island

On March 28, 1979, a partial meltdown of a reactor at the Three Mile Island Nuclear Generating Station in Pennsylvania resulted in the most serious accident in U.S. commercial nuclear power plant operating history. Although its radioactive releases had no detectable health effects on plant workers or the public, it demonstrated the need for partnership agreements and increased communication between Canada and the U.S.

This incident and COSMOS 954 prompted the Government of Canada to designate Health Canada as responsible for the mandate of coordinating a Federal Nuclear Emergency Plan.

1983, Pickering

On August 1, 1983, a pressure tube holding a fuel rod ruptured at the Pickering Nuclear Generating Station, in Ontario, Canada. Although some coolant escaped, it was recovered before it left the plant and no radioactive material was released from the containment building.

1994, Pickering

On December 10, 1994, a faulty valve led to a pipe break in a reactor at Pickering Nuclear Generating Station, in Ontario, Canada. This resulted in a major loss of coolant and a spill of 185 tonnes of heavy water. The emergency core cooling system was activated, preventing a more serious accident from occurring.

2009, Darlington

On December 21, 2009, more than 200,000 litres of water containing trace amounts of tritium, the radioactive isotope of hydrogen, was released into Lake Ontario after workers accidentally filled the wrong tank with a mixture of tritium and water at the Darlington Nuclear Generating Station in Ontario, Canada. The resulting concentration of the isotope in the lake did not pose harm to residents.

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