Wastes

Nuclear fuel waste

After reaching the end of its useful life, the nuclear fuel is removed from reactors and becomes high-level radioactive waste. Although the volumes of this solid waste are small, because of the high energy density of uranium, these radioactive wastes pose significant potential health and environmental risks. The radioactivity of used fuel can take thousands of years to decline to the same level as that of the original uranium ore. Nuclear waste also gives off heat and contains toxic chemical elements such as heavy metals.

Managing these risks and the long-lived radioactivity of these materials continues to be a major public concern and the industry’s greatest environmental and financial challenge.

Each year Canada’s nuclear power industry produces about 70,000 bundles of used fuel. Since the mid-1950s through to 2004, the industry and other sources produced about 1.7 million used fuel bundles. Tightly stacked, this amount would fill a soccer field to a height of more than one metre.

Spent fuel is stored at Canadian reactor sites in spent fuel ponds or in dry storage containers. Almost 90 per cent of the current waste fuel bundles are stored in Ontario, mostly at the Darlington and Pickering nuclear power plants near Toronto and at the two Bruce plants on Lake Huron. The remainder is stored at reactor sites in Quebec and New Brunswick.

In Canada, all nuclear fuel waste is stored in interim storage facilities at the reactor sites where they were used.

After remote-controlled removal from reactors, used fuel bundles are first stored in large water-filled pools. The water provides shielding from the radiation and cooling to remove the heat generated by the radioactive materials in the used fuel. The pools are constantly monitored and are extremely robust, built of reinforced concrete, lined to prevent leaks and designed to withstand earthquakes.

After the fuel has been in water for about seven to 10 years, the radioactivity and the heat declines enough to allow the fuel to be safely moved to dry storage in concrete silos or other containers at the reactor.

On-site interim storage of nuclear fuel waste is designed to provide safe management for used fuel. (There is enough storage space at each nuclear plant in Canada to store all the used fuel produced during the operating life of the plant.) But as some of the wastes will remain radioactive for hundreds or thousands of years, a method to dispose of these materials and contain their radioactivity must be found.

In the mid-1990s, government established an independent environmental review panel to assess the safety and public acceptability of this proposal. After public hearings, the panel concluded that the safety of the proposal was technically sound but it remains a socially unacceptable plan in Canada. In 2002, the Government of Canada passed the Nuclear Fuel Waste Act. The legislation required nuclear energy corporations to establish the Nuclear Waste Management Organization to study nuclear fuel waste management options and to recommend a long-term approach. In May 2005, the NWMO released Choosing a way forward, a draft of its study on the future of Canada’s nuclear waste disposal. Three methods of nuclear waste fuel management were evaluated: storage on site at nuclear power stations; centralized surface storage; and deep geological disposal on the Canadian Shield. The draft plan will be reviewed for public comment before the final report is submitted to the Government of Canada at the end of 2005.

As shown by the above charts, the level of radioactivity declines rapidly at first, then tapers off.

Bundles used in Canada’s CANDU nuclear reactors are composed of rods containing uranium pellets. About the size of a fire log, each bundle weights about 22 kilograms and measures half a metre in length.

Dry storage facilities hold used nuclear fuel at Ontario Power Generation’s Pickering power plant.