Used nuclear fuel consists of irradiated fuel bundles removed from commercial, prototype and research nuclear reactors. The fuel is made of ceramic uranium pellets enclosed in metal (zircalloy) tubes welded together to form a fuel bundle. Three provincial nuclear utilities (Ontario Power Generation, Hydro Québec and New Brunswick Power) own about 98 percent of the used nuclear fuel in Canada, and AECL owns the remaining two percent. Used nuclear fuel also includes research reactor fuel waste that is not in the form of a CANDU fuel bundle.
Japan’s boiling water reactors store used nuclear fuel in pools located within the reactor building.
Canada’s facilities for storing used nuclear fuel are outside of the reactor buildings.
In Canada, after nuclear fuel has been used (or “spent”) and is no longer powerful enough to generate electricity, it is removed from the reactor and transferred to interim storage facilities, which are safe, secure and environmentally sound.
Interim storage of used nuclear fuel at a nuclear facility typically takes place in two phases: wet storage and dry storage.
Wet storage facilities are reinforced, leak-proof structures that are completely separate from the reactor and allow the fuel to cool off in a shielded, secure area. During the initial wet storage, used nuclear fuel bundles are removed from a reactor and stored under water in bays or pools. The water helps provide shielding from radiation and also cools the used nuclear fuel, thereby allowing it to quickly lose its ability to generate heat. After about a day of wet storage, used nuclear fuel generates less than 1% of the heat it produced when first removed from the reactor, and the level of heat further decreases with time. Pools to store used nuclear fuel are designed and sized to safely accommodate all spent fuel produced at a reactor site. They are of the size of Olympic swimming pools and about 10 metres deep.
After 6 to 10 years in wet storage, used nuclear fuel can be safely transferred to dry storage. Dry storage takes place in concrete canisters, containers or silos.
Yes. Wet storage pools in Canada are robust concrete structures intended to withstand extreme force. Canada’s spent fuel pools have several designed safety systems to meet cooling requirements. Backup systems include:
- emergency-powered pumps
- redundant sources of power
- redundant types of power sources (such as diesel generators, gas turbines, batteries and steam-driven motors)
- redundant fire-fighting systems
- off-site emergency crews
These backup systems are designed to prevent and control events and accidents in order to protect workers and the public.
Nuclear criticality (a dangerous, accidental nuclear chain reaction) cannot inadvertently occur in Canada’s spent fuel pools — as opposed to the fuel pools for boiling water reactors and pressurized water reactors.
All of Canada’s used nuclear fuel is currently held on site in interim storage facilities, which are safe, secure and environmentally sound. There are no operating long-term management facilities for used nuclear fuel anywhere in the world, although some are under development. In Canada, the Nuclear Waste Management Organization is investigating solutions for the long-term management of used nuclear fuel.
Yes. In order to be licensed in Canada, nuclear power plants are required to follow CNSC regulations and have comprehensive emergency response plans in place. All nuclear power plant operators in Canada have well-established and practiced emergency procedures in place that include emergency shutdown of the reactors and firefighting. These facilities are inspected regularly by CNSC personnel, and emergency drills are evaluated by CNSC teams.
An emergency response plan will typically include:
- a description of the emergency plan and procedures
- a description of emergency training, drills and exercises
- personnel selection and qualification
- emergency facilities and equipment
- a public education program
Yes. Exercises are routinely conducted to simulate emergency events and to test the effectiveness of the emergency response plan. These exercises normally involve a large number of on-site and off-site stakeholders including regional, provincial and federal authorities.
The nuclear facility operators are responsible for the implementation of their emergency response plan and the on-site management of the situation.
Outside of the nuclear facility, provincial and territorial governments have the primary responsibility for protecting the health and safety of the public and the environment within their borders.
The federal government is responsible for supporting the provinces and territories in their response, and for coordinating the national response to nuclear emergencies through the Federal Emergency Response Plan (FERP), and the Federal Nuclear Emergency Plan (FNEP).
The Canadian Nuclear Safety Commission’s role involves the oversight of operators’ actions, the assessment of the safety significance of the event, and the dissemination of information to federal and provincial stakeholders.
Based on the information currently available, there is no radiation health risk to Canadians resulting from the events in Japan.
Health Canada conducts regular radiation surveillance and monitoring activities across Canada. The fixed radiation monitors, located on the Canadian West Coast, have detected very minute levels of isotopes which are indicative of the release in Japan. The actual increase in radiation measured was 0.0005 µSv, which is so small that it is extremely difficult to measure against normal background radiation and does not pose any health risk. Natural background radiation varies from location to location in Canada but the national average is in the order of 1,800 μSv per year.
The CNSC has access to this data and is monitoring it on a daily basis.
Any food products entering into Canada will be screened as per normal protocols by the appropriate federal departments. If any radioactive substances are found in excess of limits outlined in the Nuclear Substances and Radiation Devices Regulations, they would be quarantined and transferred to a Canadian Nuclear Safety Commission–licensed facility for safe storage and disposal.
Health Canada has implemented what are called action levels for radionuclides in food, which can be applied during a radiation–related emergency. The action level is applied to specific radionuclides based on the risk they represent and is significantly higher than the detection limits used.
The CODEX Alimentarius, an international scientific organization focused on food additives and contaminants has also established recommended limits for specific radionuclides in food, which are consistent with Health Canada’s action levels.
For more information on these action levels, please visit the Health Canada Web site.
Radiation is energy that is transmitted in the form of waves or streams of particles. It is present everywhere in our environment. There are two types of radiation – ionizing and non-ionizing.
Ionizing radiation includes the radiation that comes from both natural and man-made radioactive materials such as cosmic rays, nuclear power plants, and x-ray machines.
Non-ionizing radiation is a lower energy radiation such as radio waves, ultraviolet rays, microwaves, and sunlight.
Radiation has always been present all around us. It comes from space, the ground, and even within our bodies.
The doses due to natural sources of radiation vary depending on location and habits. Regions at higher altitudes receive more cosmic radiation. Air travel also increases exposure to more cosmic radiation.
There are also natural sources of radiation in the ground. For example, some regions receive more terrestrial radiation from soils that are enriched with uranium, depending on location and geology. In Canada, the estimated highest annual dose is approximately 2.3 mSv measured in the Northwest Territories.
The earth’s crust also contributes to our levels of exposure. Radon gas, which is produced by the earth, is present in the air we breathe. There are four decay products of radon with very short half-lives that will irradiate the lungs if inhaled. Radon gas naturally disperses as it enters the atmosphere from the ground.
Finally, there are a number of sources of natural radiation that penetrate our bodies through the food we eat, the air we breathe and the water we drink. Potassium-40 is the main source of internal irradiation (aside from radon decay).
When ionizing radiation penetrates the human body or an object, it deposits energy. The energy absorbed from exposure to radiation is called a dose.
A person’s radiation exposure due to all natural sources amounts on average to about 2.4 millisievert (mSv) per year. A sievert (Sv) is a unit of effective dose of radiation. Depending on geographical location, this figure can vary by several hundred percent.
Since one sievert is a large quantity, radiation doses are typically expressed in millisievert (mSv) or microsievert (µSv), which is one-thousandth or one millionth of a sievert. For example, one chest X-ray will give about 0.1 mSv of radiation dose.
The Canadian Radiation Protection Regulations set limits on the amount of radiation the public and nuclear energy workers may receive.
In Canada, the effective dose limit for the public is 1 mSv in one calendar year. Regular reporting and monitoring demonstrates the average annual effective doses to the public from activities licensed by the CNSC range from 0.001 to 0.1 mSv per year.
The effective dose limit for a nuclear energy worker is set at 50 mSv in any one year and 100 mSv in five consecutive years.
Most people who showed health effects in studies were exposed to relatively high doses (greater than 100 mSv) delivered in a very short period of time. This is known as “acute” exposure. Normally, workers and members of the public exposed to radiation from the nuclear industry receive much lower doses over a much longer period of time (years as opposed to seconds). This is known as “chronic” exposure. Acute radiation exposures are estimated to be about 1.5 to 2 times more effective in causing health effects.
The CNSC would like to reassure Canadians that nuclear power plants (NPP) located in Canada are among the most robust designs in the world and have redundant safety systems to prevent damage in the case of an earthquake.
All Canadian NPP have been designed to withstand potential earthquakes. Both the actual structures that form containment and the systems important to safety have been seismically qualified. That is they are designed and built or refurbished to meet seismic standards. CNSC has reviewed and inspected these installations to confirm their robustness with regards to potential earthquakes.
Similarly, waste management facilities are designed to withstand seismic events (as defined under the National Building Code).
All nuclear power plant operators in Canada have well-established and practiced emergency procedures in place that include emergency shut down of the reactors and firefighting. These facilities are inspected regularly by CNSC personnel and emergency drills are evaluated by CNSC teams.
The CANDU design uses the concept of defense-in-depth to ensure that there are many barriers (or layers of protection) to prevent undesirable events or in the occurrence of an event such an earthquake or other emergency, to mitigate the consequences.
Types of barriers are: physical (pipes, shielding, buildings built to standards to contain radioactive substances), safety systems (systems that shut down facilities or control equipment; systems that contain radioactivity; emergency core cooling systems) and programmatic (quality management systems, processes and procedures); and operators are trained for routine and abnormal operations, including emergencies, etc.
The CNSC has inspectors at all nuclear power plants; the waste storage facilities are co-located at the plants so staff is available to inspect facilities and confirm that licensees are following their procedures.
The CANDU reactors are quite different from the Japanese NPPs, in a number of ways. While some of the difference will have no impact on the effects of a major earthquake, there are features that promote resilience of CANDU to this kind of events.
- First of all, the NPP in Canada are located in areas where major earthquakes are not expected, and tsunami essentially cannot happen.
- Secondly, there are multiple, different in design, and physically separated, sources of back-up electricity. This feature was reviewed and reinforced following the black-out event in 2003, giving confidence that there will be sufficient power to maintain all essential systems even if the electric grid is affected by an earthquake.
- CANDU reactors are equipped with two fully capable, independent shutdown systems that will assure that reactors are placed in a safe shutdown state in case of an earthquake.
- CANDU reactors also have larger inventories of water (such as the primary coolant, emergency coolant, moderator, Steam Generator inventory, and others) that will be available to remove the heat from the core.
CANDU reactors have two shutdown systems which must meet strict design and operational requirements and are maintained to assure extremely high reliability. Both shut down system are fully capable - meaning that each of them, acting alone, can terminate the on-power operation and maintain the reactor in a shutdown state without reliance on the other system. These systems are also physically and operationally independent, meaning that they do not rely on the same detectors or sources of power, and any failure in one of the system cannot affect the other system. This design feature gives us assurance that CANDU reactors can be safely shutdown in case of an emergency.
The CANDU reactors also have multiple ways of keeping the fuel cool after shutdown including seismically qualified primary heat transport system and emergency core cooling systems.
CNSC staff confirms that all Canadian NPPs are equipped with back-up electrical generators. The specific equipment design and lay-out varies between NPPs. There is sufficient redundancy in place at each Canadian NPP to provide the reliable back-up electrical supply.
The design of CANDU NPPs varies significantly from the design of Pressurized Water Reactors (PWR) and Boiling Water Reactors (BWR). The CANDU NPPs are equipped with seismically qualified Emergency Power Supply (EPS) generators. These EPS generators supply power for essential equipment to maintain the reactor in safe state.
Yes, the CNSC's head office has a back-up generator, as well as another site to relocate to if necessary.
Venting is sometimes performed to relieve the pressure inside the containment building. In this way, the releases can be controlled and monitored. Any such releases are planned and executed in order to ensure minimum off-site effects.
In Canada, reactor sites are geologically screened to ensure they are constructed in a location that is seismically stable.
CANDU nuclear technology is designed to withstand earthquakes of a magnitude greater than the largest known earthquake for the region where it is being built. "Withstand" means that the reactor has the ability to automatically shut down and cool the core without a release of radiation.
As a licensing requirement, nuclear reactors must be qualified to withstand the level of seismic activity that is expected for each individual reactor location. Seismic qualification is a common component of civil and mechanical design, and nuclear reactors do not differ from any other major infrastructure in this respect. The same robustness and defense-in-depth approach that assures safety and security of a nuclear plant plays a major role in its seismic qualification, and often provides a level of conservatism that continues to protect even during very unlikely events.
Public Safety Canada maintains the Federal Emergency Response Plan and works closely with provincial and territorial emergency measures organizations to promote emergency preparedness. Earthquake prone regions of Canada have earthquake-specific emergency response plans that are exercised on a regular basis. For more information, go to: www.publicsafety.gc.ca.
In Canada, nuclear reactor sites are selected to minimize the possibility of external flooding. Nevertheless, as part of an external hazard assessment, the consequences of external flooding are considered in the reactor design to ensure effectiveness of all safety-related systems credited for automatic shutdown and cooling of the reactor.
The Government of Canada, through the Government Operations Centre, is monitoring and assessing the situation at nuclear plants in Japan in order to assess any potential risks to Canadians.
A number of federal departments and agencies are working together, with other national and international organizations, to monitor the situation in Japan for any potential threats to the health and safety of Canadians:
Health Canada is the Government of Canada lead agency on the impact to human health from potential radiation exposure. Health Canada is currently monitoring the health risks from the possible radiation leak in Japan.
Environment Canada is providing support to Health Canada by running highly specialized computer-based simulations to predict the long-range movement of airborne radioactivity and identify geographical areas that might be affected by a radiation release.
The Canadian Nuclear Safety Commission (CNSC) has activated its Emergency Operations Center and is actively monitoring the situation following the earthquake in Japan and the potential damage to Japan’s nuclear power plants. The CNSC works in close collaboration with the Department of Foreign Affairs and International Trade, the International Atomic Energy Agency’s International Seismic Safety Centre, the Organisation for Economic Co-operation and Development Nuclear Energy Agency, and the U.S. Nuclear Regulatory Commission.
The Department of Foreign Affairs and International Trade is monitoring the situation in Japan and providing advice to Canadians living in Japan as well as those who may be planning to travel there.
Public Safety Canada is coordinating and supporting the efforts of federal organizations to ensure the safety of Canadians.