A public interest information project about nuclear waste burial in Canada.

Know Nuclear Waste 

Radioactive wastes are created at each stage of the nuclear fuel chain: uranium mining, milling, refining, fabrication, and end uses (including military, medical and electricity production).


Wastes are classified into low-level, intermediate level or high level;  classification of waste follows two criteria : the duration of the radioactivity and the intensity of this radioactivity. Duration is linked with the time necessary for the radioactivity of a radio-active element to be cut in half, called the half-life.


  • Low-level Waste - generated from hospitals, laboratories and industry (paper, rags, tools, clothing, filters etc.) plus uranium mining wastes
  • Intermediate-level Waste - contains higher amounts of radioactivity and may require special shielding; includes resins, chemical sludges and reactor components, as well as contaminated materials from reactor decommissioning.
  • High-level Waste - irradiated nuclear fuel; also called spent fuel, nuclear fuel waste. Note that reactor components can also be highly radioactive, but are not categorized as "high level waste".

Definition: Radioactive by-products resulting from fusion, fission, refinement, or processing of radioactive materials.  Definition Source: Webster's II New Riverside University Dictionary


Nuclear fuel waste is also called high level waste, spent fuel, or highly radioactive waste, and is created  by operating nuclear reactors, which convert the uranium fuel into high level radioactive waste

Nuclear fuel waste consists of fuel bundles that have been used by a nuclear power plant to generate electricity and then removed from the reactor. A fuel bundle is about the size and shape of a fireplace log. It weighs about 24 kilograms and is about half a metre long.

  • Over 99 percent of the radioactivity created by a nuclear reactor is contained in the spent fuel.
  • An unprotected individual standing one metre from a CANDU fuel bundle just out of the reactor would receive a lethal dose in seconds.
  • Nuclear fuel waste is one million times more radioactive than the uranium in the fuel bundle before being placed in the reactor
  • Nuclear fuel waste takes one million years to "decay" to the same level of radioactivity as the uranium fuel


Nuclear fuel waste contains hundreds of radioactive substances created inside the reactors: (1) when uranium atoms split, the fragments are radioactive; these are the "fission products"; (2) when uranium atoms absorb neutrons without splitting, they are transmuted into "transuranium elements" such as plutonium, americium, and curium. Due to the presence of these toxic materials, spent fuel remains extremely dangerous for millions of years.

Nuclear power plants have been producing electricity commercially in Canada since the early 1960s. Today, five plants in three provinces house 22 nuclear power reactors

  • Bruce Nuclear Generating Station, Ontario (8 reactors)
  • Pickering Nuclear Generating Station, Ontario (4 reactors operating, 4 shut down)
  • Darlington Nuclear Generating Station, Ontario (4 reactors)
  • Gentilly-2 Nuclear Facility, Québec (1 reactor,  shut down)
  • Point Lepreau Generating Station, New Brunswick (1 reactor)

As of June 30, 2024, a total of approximately 3.3 million used CANDU fuel bundles (about 64,260 tonnes of heavy metal (t-HM)) were in storage at the reactor sites, an increase of about 74,550 bundles since the 2023 NWMO Nuclear Fuel Waste Projections report. The inventory increases on average by 80,000 bundles per year. 

For the existing reactor fleet, the total projected number of used fuel bundles produced to the end of life of the reactors is approximately 5.9 million used CANDU fuel bundles (approximately 112,750 t-HM).

This projection is based on published plans as of September 2024 and NWMO planning assumptions regarding the refurbishment and life extension of Darlington and Bruce reactors, as well as continued operation of Pickering A until 2024 and Pickering B until the end of 2026. Additional scenarios included in this year’s estimates provide a range of forecasts (5.7 to 6.4 million bundles) to reflect uncertainties in future life extension plans of the existing reactor fleet. [Source: Nuclear Fuel Waste Projections in Canada – 2024 Update, NWMO-TR-2024-09, Nuclear Waste Management Organization, November 2024]

What is nuclear waste?