Nuclear and Geothermal Technology and Society

More than electricity

When people hear "nuclear", many think only of power plants. But on any given day in Canada, radioisotopes are helping doctors find and treat cancer, sterilizing syringes and bandages, protecting orchards from pests and checking welds in pipelines.

These technologies bring big benefits and real risks. Deciding how to use them, and what to do with their waste, involves physics, but it also involves health, the economy, the environment, and the rights of the communities affected. In this lesson you will look at several technologies and practise weighing evidence, the way the curriculum asks you to (expectation D1.2).

Medicine

• Diagnosis: a radiopharmaceutical is injected, swallowed or breathed in, travels to a particular organ, and gives off gamma rays that a special camera detects. Technetium-99m (half-life about 6 hours) is the most widely used. It comes from the decay of molybdenum-99 (half-life about 66 hours), which is made in nuclear reactors. For decades, the NRU research reactor at Chalk River, Ontario, produced a large share of the world's molybdenum-99; it closed in 2018, and supply now comes from several reactors around the world.
• Treatment: high-energy gamma rays from cobalt-60 are aimed at tumours to destroy cancer cells, and iodine-131 is used to treat some thyroid conditions. In 1951, teams in Saskatoon (led by physicist Harold Johns) and in London, Ontario, were among the first in the world to treat cancer patients with cobalt-60 radiation.
• Sterilizing medical supplies: gamma rays from cobalt-60 kill bacteria on sealed packages of syringes, gloves and bandages without heating them. Canada is a major supplier of cobalt-60, produced in some Ontario CANDU reactors.

Benefits: earlier diagnosis, effective treatment, safer supplies. Risks and costs: patients and workers receive radiation doses (kept as low as reasonably achievable); short half-lives mean supply chains must be fast and reliable; radioactive sources must be secured and disposed of safely.

Food and agriculture

• Food irradiation exposes food to gamma rays, X-rays or electron beams. The radiation kills bacteria such as E. coli and Salmonella, kills insects, and slows sprouting in potatoes and onions. The food is not made radioactive (the radiation passes through it, just as an X-ray passes through you). Canada allows irradiation of a limited list of foods, such as potatoes, onions, spices and ground beef, and irradiated foods must carry the Radura symbol.
• Sterile insect technique: large numbers of insects are raised and made sterile with radiation, then released. When wild insects mate with the sterile ones, no offspring are produced, so the pest population shrinks without spraying as much pesticide. In British Columbia's Okanagan Valley, this method has been used for many years to control the codling moth, a pest of apple orchards.

Benefits: fewer food-borne illnesses, less spoilage, less pesticide. Concerns: some consumers distrust irradiated food; irradiation facilities use powerful sources that must be secured; sterile insect programs cost money every year.

Geothermal and thermal technologies

Geothermal energy is thermal energy from inside the Earth.

• Where very hot rock or underground steam is close to the surface (for example in Iceland and parts of California), geothermal power plants use the steam to spin turbines. In a dry-steam plant, steam comes straight from the ground; other plants use very hot water that "flashes" into steam. Benefits: steady, low-emission power. Costs: drilling is expensive and works only in suitable places; underground fluids can carry dissolved gases and minerals that must be managed.
• Most of Canada does not have hot rock that close to the surface, but ground-source heat pumps (from Heat Pumps, Refrigerators and Thermal Technologies) work almost anywhere. They cut heating costs and emissions but cost more to install, and their buried loops must be protected against antifreeze leaks.
• Other thermal technologies with social and environmental impacts include thermal regulating units that keep vaccines and medicines at the right temperature, and cold-chain shipping that fast-freezes food so it can travel long distances.

Managing used nuclear fuel

Canada's nuclear reactors have produced used fuel since the 1960s. Freshly removed bundles are very hot and highly radioactive, so they are first stored in deep water pools at the station for several years (water cools them and shields the radiation). Then they are moved into thick dry storage containers at the reactor sites.

Because some radioisotopes in used fuel have half-lives of thousands of years (from Radioactive Half-Life), the long-term plan must protect people and the environment for a very long time. The Nuclear Waste Management Organization (NWMO) plans a deep geological repository: used fuel sealed in copper-coated steel containers, surrounded by a buffer of bentonite clay (which swells to block water), placed in tunnels hundreds of metres deep in stable rock. Each barrier slows any escape.

Where to build such a site is as much a social decision as a scientific one. The NWMO's process was designed so that a site would be chosen only with the willingness of the local municipality and of the First Nations and Métis communities in whose territory it would be built. In late 2024, after years of study and dialogue, the NWMO selected an area in northwestern Ontario where both Wabigoon Lake Ojibway Nation and the Township of Ignace had said they were willing to host the project. In contrast, in 2020 members of the Saugeen Ojibway Nation voted against a separate proposal by Ontario Power Generation to build a repository for low- and intermediate-level waste near the Bruce station, and that proposal did not go ahead. These decisions show that First Nations hold rights and responsibilities for their lands and waters, and that their consent shapes how nuclear projects proceed.