How is Radioactive Waste Classified?

The Canadian Standards Association (CSA)—in collaboration with industry, government and CNSC—has developed a standard that recognizes four main
classes of radioactive waste:

Low-level radioactive waste
Intermediate-level radioactive waste
High-level radioactive waste
Uranium mine and mill waste

The waste classification system is generally organized according to the degree of containment and isolation that is required to ensure safety in the short- and
long-term. It also takes into consideration the hazard potential of the different
types of radioactive waste.

1 & 2) Low-Level and Intermediate-Level Radioactive Waste

In Canada, low-level radioactive waste (LLRW) contains material with radionuclide content that is above established clearance levels and exemption quantities but generally has limited amounts of long-lived activity. LLRW generally does not require significant shielding during handling and interim storage. Shielding refers to a barrier between stored waste and nuclear workers, such as a concrete wall or protective clothing.

Image: Low-level radiation waste facility (Source: AECL)

Intermediate-level radioactive waste (ILRW) typically shows levels of penetrating radiation sufficient enough to require shielding during handling and interim storage.

Canada does not have, at present, a long-term management facility to accept all low and intermediate-level waste. The owners of low- and intermediate-level waste (L&ILRW) are responsible for managing the waste they produce. This usually takes place on site within its own facility.

How is low-level and intermediate-level radioactive waste managed?

The owners of low- and intermediate-level radioactive waste (L&ILRW) are responsible for managing the waste they produce. This usually takes place on site within its own facility. Currently, Canada does not have a long-term management facility for low- and intermediate-level waste to accept all low- and intermediate-level radioactive waste. All L&ILRW in Canada is currently held on site in interim storage facilities, which are safe, secure and environmentally sound.

Image: Dry storage of nuclear fuel waste (Source: OPG)

Certain types of radioactive waste, such as that from hospitals, universities and industry, contain only small amounts of radioactive materials with short half-lives. This means that radioactivity decays away in hours or days. After safely holding the waste until the radioactivity has decayed to levels authorized by the CNSC, it can then be disposed of by conventional means (in local landfill or sewer systems).

With the notable exception L&ILRW originating from nuclear power plants, low- and intermediate-level radioactive waste that requires long-term management may be returned to the manufacturer or may be transferred to an authorized waste management operator such as the waste management facility operated by AECL at its Chalk River Laboratories on a fee-for-service basis.

3) High-level radioactive waste

Image: Fuel bundle

High-level radioactive waste is used (irradiated) nuclear fuel and/or waste that generates significant heat. Canada’s nuclear power program has produced over two million used fuel bundles over the past half century. If these bundles were stacked end-to-end, they would fit into a space the size of six hockey rinks stacked to the top of the boards. At present, there are currently no long-term management facilities for high-level nuclear fuel waste anywhere in the world. All used nuclear fuel in Canada is currently held on site in interim storage facilities, which are safe, secure and environmentally sound. Finding solutions for the long-term management of used nuclear fuel is the responsibility of the NWMO.

How is high-level radioactive waste managed?

All used nuclear fuel in Canada is currently held on site in interim storage facilities, which are safe, secure and environmentally sound. Interim storage of used nuclear fuel at a nuclear facility typically consists of two phases known as wet storage and dry storage.

Initially, used nuclear fuel bundles are stored under water in bays or pools after they have been removed from the reactors. These reinforced, leak-proof facilities enable the fuel to cool off in a shielded and secure facility.

After 6 to 10 years in wet storage, the used nuclear fuel can be safely transferred to dry storage in concrete canisters, containers or silos.

At present, there are currently no operating long-term management facilities for used nuclear fuel anywhere in the world, although some are under development. Finding solutions for the long-term management of used nuclear fuel is the responsibility of the NWMO.

4) Uranium mine and mill waste

Uranium mine waste rock and mill tailings are specific types of radioactive waste generated during the mining and milling of uranium ore and production of uranium concentrate. In addition to tailings, mining activities produce large quantities of mineralized and unmineralized waste rock, excavated in order to access the uranium ore body. The tailings and mineralized waste rock contain significant concentrations of long-lived radioactive elements, primarily thorium-230 and radium-226, which will not significantly decrease over a long period of time.

How are uranium mines and mills managed?

In general, long-term management in near-surface facilities adjacent to the mines and mills is the only practical option for these wastes, given the large volumes of waste generated in mining and milling operations. The tailings are monitored and managed in facilities, such as engineered tailing ponds or placed back in mined-out open pits. Cameco Corporation and Areva Resources Inc. manage the only operating uranium mines and mills in Canada.

Image: Engineered tailing pond (Source: AREVA)

Regarding inactive facilities, such as the mining and tailings facilities around Elliot Lake, in Ontario, the facilities have been decommissioned and the former operators continue to carry out monitoring and maintenance activities. There are also former uranium mining and milling sites located in Saskatchewan, Ontario and the Northwest Territories. These inactive sites are being managed for the long-term by their former owners or the federal or provincial government.

There is an initiative to remediate inactive legacy uranium mine and mill sites in Northern Saskatchewan that were decommissioned during the end of the Cold War era and do not meet today’s environmental standards.

Through regular facility visits and inspections, harmonized with the Saskatchewan departments of Environment and Resource Management, and Labour, CNSC staff monitor these waste management facilities to protect workers, the public and the environment.