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A male worker in a hard hat takes measurements beside metal boxes containing low-level waste (mop heads, rags, floor sweepings) stacked five high above his head.

Types of waste

Ontario Power Generation’s safe and reliable nuclear energy production includes the effective management of waste by-products.

Learn about OPG’s commitment to effective, long-term management of waste, for the future of all Ontarians.

What is nuclear waste?

Generating electricity from uranium creates by-products known as nuclear waste.

In a nuclear plant, there are three types:

  • Used fuel
  • Intermediate-level waste
  • Low-level waste

OPG employs different management techniques for the handling and storage of each type.

Types of waste

Explore the types of waste

From storage to long-term management, see how OPG manages nuclear waste.

For CANDU® (CANadian Deuterium Uranium) reactors, nuclear fuel is uranium dioxide processed into ceramic pellets, sealed in tubes. The tubes are welded together to form fuel bundles.

Heat generated by splitting of the uranium atoms (fissioning) turns water into steam, which runs turbines to create electricity.

When a fuel bundle no longer contains enough fissionable uranium to heat water efficiently, it gets replaced by a new fuel bundle.

The used fuel contains more than 99% of the radioactive by-products of nuclear reactors.

The used fuel bundle, still emitting heat and radioactivity, is removed from the reactor by remote control and deposited into a water-filled bay built of reinforced concrete, lined to prevent leaks, and designed to withstand earthquakes.

The water in the bay cools and shields the bundles as the heat and radioactivity gradually declines. Used fuel is stored in water for 10 years or more.

After fuel bundles ‘cool’, they are transferred to Canadian Nuclear Safety Commission (CNSC)- licensed dry storage containers made of concrete and steel, which are welded closed, and affixed with International Atomic Energy Agency (IAEA) seals to verify compliance with the International Non-proliferation Treaty.

When loaded, these containers weigh about 79 tonnes and have a design life of 50 years. Studies indicate that ongoing maintenance and inspection can support safe use of the containers for a much longer time.

In 2002, the Canadian Government required a proposal for the long-term management of used nuclear fuel from representatives of Canada’s nuclear utilities, through the new Nuclear Waste Management Organization (NWMO).

The NWMO conducted a survey of over 18,000 people to understand what Canadians believe is important in managing used fuel over the long term.

Input from the public, 500 specialists, and 2,500 Aboriginal people helped shape this proposal, submitted to the Minister of Natural Resources in November 2005 and approved by the government in June 2007.

In 2010, the NWMO began the process to identify an informed and willing host for Canada’s own repository, and opened it to all interested communities. Twenty-two communities in Saskatchewan and Ontario expressed an interest in learning more about the project.

After years of consultation the NWMO has narrowed its focus to five of the communities and expects to identify a preferred site by 2023.

This Adaptive Phased Management plan calls for isolation and containment of used fuel from Canadian nuclear facilities in a central repository deep underground.

The used fuel is contained by engineered barriers and the surrounding geology, is constantly monitored, and remains retrievable indefinitely, if necessary.

Importantly, Adaptive Phased Management is flexible. Throughout the plan’s implementation Canadians will be engaged in a voluntary, transparent process, invited to make their views known at key decision points, and have genuine opportunities to influence progress and outcomes.

This includes used reactor components, as well as the resins and filters used to keep reactor water systems clean.

These items, which cannot be handled without shielding, are loaded into specially reinforced and shielded transportation packages licensed by the CNSC for shipment to the Western Waste Management Facility (WWMF) in Bruce County.

There, waste is stored in steel-lined, in-ground storage structures.

Minimally radioactive materials such as mop heads, rags, paper towels, floor sweepings and protective clothing used in the nuclear stations during routine operation and maintenance must be addressed as well.

These items do not require shielding and are packed in plastic bags and shipped to the WWMF in CNSC-licensed steel containers for processing and storage.

These materials are compacted or incinerated whenever possible to reduce their volume, so that the concrete warehouses used to store them can be designed with smaller environmental footprints.

How is waste managed?