Radiation and nuclear accidents

Radiation and nuclear accidents involve the discharge of radioactive materials outside the containers or facilities that normally house them. Such an accident could happen if a complication arose during the transportation or use of radioactive materials for medical or industrial purposes, or if a serious operational problem were to occur in a nuclear facility, especially a nuclear plant.

The most serious accident would stem from overheating of the reactor core at a nuclear power plant, which would release radioactive materials outside the reactor. However, safety mechanisms are in place to prevent such an accident from occurring.

Find out more about radiation and nuclear hazard:

Understand the consequences for human health

The discharge of radioactive materials can affect human health. In particular, it can increase the risk of developing cancer. The impact on health depends on:

  • The intensity of the source of radiation
  • Proximity
  • The type of radiation
  • Exposure time

People may be exposed to:

  • External irradiation, near the source of radiation, a risk that mainly concerns personnel at nuclear power plants
  • Internal contamination, caused by breathing in radioactive elements, by ingesting contaminated food or water, or when radioactive elements enter the body through a wound. Radioactive materials are deposited on certain organs, in particular the thyroid gland
  • External contamination, when radioactive dust settles on the skin, hair and clothing
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Find out about facilities are at risk in your area

In Québec, in the Centre-du-Québec region, the Gentilly-2 nuclear plant ceased operations in December 2012. A residual risk analysis by experts in radiological risk assessment indicates that the nuclear facility no longer represents a danger for the surrounding population, thanks to the work of decommissioning begun in 2013. That being the case, the protection measures applied in recent years, including the taking of stable iodine tablets, are no longer necessary.

In the Outaouais region, the south portion or the controlled use zone (Z.E.C.) St-Patrick, in the municipality of Sheenboro, is located in the perimeter where measures were taken in case of an accident at the Canadian Nuclear Laboratories, in Chalk River. These measures are contained in a special action plan.

In the event of a nuclear accident, take shelter

The first step in the event of a nuclear accident is to take shelter. This applies to a limited perimeter around the accident site. The following precautions should also be observed:

  • Do not attempt to return to your home if you have taken shelter elsewhere. In public places, such as a shopping centre, your safety is ensured by the personnel, the police or firefighters.
  • Keep your children at school or the day care centre, as they are sheltered and safe there.
  • Do not take shelter in your car if you can take shelter in a house, since a vehicle is not as effective as a building to protect you from radioactive materials.
  • Close the windows and the ventilation system of your car if you have no other choice than to take shelter in it.

Take shelter for as long as the authorities ask you to. Radioactive materials discharged into the environment are invisible and odourless.

Take iodine tablets if prescribed

When recommended by the director of public health, take the prescribed dose of iodine tablets. The tablets saturate the thyroid gland with stable (non-radioactive) iodine. As a result, the thyroid gland can no longer absorb or retain radioactive iodine, which is then removed naturally by the body. This reduces the risk of internal contamination. Iodine tablets only protect the thyroid gland, and only against radioactive iodine. Their use is complementary to taking shelter, which protects the entire body against radiation.

Iodine tablets are distributed to residents living near nuclear sites. Residents located within a 9-km radius around the reactor stack of the Canadian Nuclear Laboratories received iodine tablets.

At home, iodine tablets should be kept in the same location as other medication, in a safe, warm place (15 °C to 30 °C), out of reach of children and away from light and humidity.

Contraindications to taking iodine tablets

Generally speaking, there are very few people for whom it is contraindicated to take stable iodine. They include anyone presenting

  • a known allergy to iodine (allergies to seafood or to contrast agents used in radiological examinations are not contraindications however);
  • a thyroid disorder, such as hyperthyroidism, in association with a cardiac disorder;
  • one of the following rare disorders: dermatitis herpetiformis, hypocomplementemic vasculitis, congenital myotonia, pemphigus vulgaris and tuberous iododerma.

Secondary effects of iodine tablets

Secondary effects associated with taking iodine tablets are very rare. Mild and temporary discomfort may occasionally occur. In most cases these symptoms disappear without treatment.

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Follow the instructions of the authorities

In the event of a nuclear accident, consult the media for instructions issued by the authorities.

In the event of environmental contamination, the authorities may, for example, prohibit consumption of fresh food and water, or certain outdoor activities. Radioactive releases can contaminate, to different degrees, the air, water, soil and food within a radius that may vary, depending on the circumstances.

Evacuate your home

In addition, the authorities may order the preventive evacuation of a sector prior to the possible release of radioactive materials or the evacuation of a sector within a close perimeter of the accident in the event of prolonged exposure to radioactive releases.

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