A nuclear or radiological emergency is an emergency event that has led, or could lead, to a radiological threat to public health and safety, property, or the environment.
Nuclear or radiological emergencies that could affect Canadians include:
In Canada, every level of government has responsibility in the event of a nuclear or radiological emergency. Response begins at the local or municipal level, and progresses to the provincial and federal levels, depending upon the location, type, and size of the emergency. As a signatory country on two International Atomic Energy Agency (IAEA) conventions, Canada also has a responsibility to notify other countries if it has had a radio-nuclear incident, and to assist other countries with their own emergency response to a nuclear emergency if requested to do so.
The International Nuclear Event Scale (INES) was developed by the International Atomic Energy Agency (IAEA) and the Nuclear Energy Agency (NEA) of the Organisation for Economic Co-Operation and Development (OECD) in order to communicate the magnitude and safety significance of nuclear emergencies between countries around the world, including Canada.
According to the INES system, a nuclear emergency is classified on the scale at one of seven levels. In general, the higher the classification level, the greater and more widespread is the safety significance. The categories are grouped as follows:
This is a graphic of the International Nuclear Event Scale:
The Canadian Nuclear Safety Commission, in consultation with the company affected, sets the INES level for emergencies in Canada. The level will not be available immediately when the emergency occurs because it takes time to collect and review all of the necessary information. It is also possible that with further information, the emergency level may change. For example, while an emergency might initially be classified as low on the INES scale, subsequent complications may result in an INES classification to a higher level.
Emergencies are not classified on the INES scale if they are not of nuclear or radiological significance. For example, a fire at a nuclear power station is not classified if it does not involve radiological material. The INES classification should not be confused with emergency classification systems used at nuclear facilities to tell staff and local authorities what to do in response to an emergency.
On 24 January 1978, COSMOS 954, a Soviet nuclear-powered surveillance satellite, crashed in the Northwest Territories. The crash scattered an enormous amount of radioactivity over a 124,000 square kilometre area in Canada's north, stretching southward from Great Slave Lake into northern Alberta and Saskatchewan.
The clean-up operation was a coordinated event between the United States and Canada. Dubbed "Operation Morning Light", the clean-up effort continued into October 1978 and resulted, according to the Atomic Energy Control Board (now the Canadian Nuclear Safety Commission) , in the estimated recovery of about 0.1 percent of COSMOS 954's power source.
The crash of COSMOS 954 raised international policy questions. Soon after the satellite's crash, there was a call from the United States to prohibit satellites containing radioactive material from orbiting the earth. This was followed by similar calls from Canada and countries in Europe. In November 1978, the United Nations authorized its Committee on the Peaceful Uses of Outer Space to set up a working group to study nuclear-powered satellites.
On 28 March 1979, there was an accident at the Three Mile Island nuclear power station near Harrisburg, Pennsylvania. There were no injuries or adverse health effects to the public from this accident. Although some radioactive gas was released a couple of days after the accident, it was not enough to cause any dose above regular background levels to local residents. However, conflicting information released during the event exacerbated the public's fears, highlighting the need for a consistent and coherent public information and emergency communication strategy.
The accident also highlighted the need for both national and international plans to handle a peacetime nuclear emergency . As a direct result of this accident, Canada and the United States created the Canada-United States Joint Radiological Emergency Response Plan (JRERP), an agreement ensuring mutual assistance in the event of a peacetime radiological event that could affect either, or both, countries.
On 26 April 1986 the world's most severe nuclear reactor accident occurred in Chernobyl, Ukraine (at that time part of the Soviet Union). An area of about 5 million hectares - almost the size of Nova Scotia - was contaminated and 160,000 people had to be permanently evacuated. Radioactive material affected not only the Ukraine but also neighbouring countries and parts of Western Europe.
The Chernobyl accident demonstrated the need to include the possibility of trans-boundary implications in national emergency plans. The concern that any country could be affected not only by nuclear accidents occurring within its own territory but also by the consequences of accidents happening abroad, stimulated the establishment of national emergency plans in several countries. Also, the trans-boundary nature of the contamination resulting from the Chernobyl accident prompted international organizations to promote international cooperation and communication, to harmonize actions, and to develop international emergency exercises such as the Nuclear Energy Agency's INEX series. The international community reached agreements on early notification in the event of a radiological accident and on assistance in radiological emergencies through international conventions developed by the International Atomic Energy Agency and the Nuclear Energy Agency.