Nuclear power is regaining momentum as governments look to diversify energy supplies and reduce dependence on fossil fuels. But one of the industry’s biggest unresolved issues remains unchanged: how to store nuclear waste safely over the very long term.
Nuclear waste falls into three categories: low-, intermediate-, and high-level radioactive waste. Most waste generated by nuclear plants consists of lightly contaminated materials such as tools and work clothing, with radioactivity levels of around 1 percent. Spent fuel, by contrast, makes up roughly 3 percent of total waste volume but accounts for 95 percent of the radioactivity.
While nuclear plants produce relatively small amounts of waste compared with many other energy sources, that waste is among the hardest to manage. The source notes that just 5 grammes of high-level waste corresponds to one person’s annual energy needs. A conventional 1 GW nuclear plant, capable of supplying electricity to more than one million people, produces around three cubic meters of vitrified high-level waste each year.
Canada’s repository push
In Canada, the Nuclear Waste Management Organisation (NWMO) has built a test site in Oakville to refine a long-term storage system for spent nuclear fuel. The concept uses copper-coated steel containers surrounded by bentonite clay blocks and sealed deep underground in rock tunnels. The aim is to isolate radioactive material for thousands of years without creating a risk to the public.
The containers are designed to withstand extreme pressure. According to the source, they are built to hold up even if a future ice age leaves the site under a 3-kilometre-thick glacier before the radiation has fully decayed. They have also been tested against crushing forces equivalent to being more than 6 km underwater.
NWMO plans to build the final facility 1,600 km northwest of the test site, near the town of Ignace, Ontario. The repository would sit about 750 metres underground in the hard rock of the Canadian Shield. If completed on schedule, around 2040, it is expected to hold nearly 6 million bundles of spent fuel produced by Canada’s four nuclear power plants over their operating lives.
Other countries and the US backlog
Similar deep geological repositories are also being developed in Finland, Sweden, and Japan. Scientists have addressed a number of technical barriers over the years, making such facilities increasingly viable. Even so, public and political support remains difficult to secure because of long-standing fears of contamination.
In the United States, the federal government has been studying potential repository sites since the 1980s, but progress has lagged behind other countries. Yucca Mountain in northern Nevada was selected for what would have been the country’s first permanent geological repository. The project has faced both geological and political objections. The source points to a nearby volcano that geologists still regard as active, the site’s location in an earthquake zone, and its position above the water table, all of which have raised concerns about radionuclides escaping into the environment.
Politics, however, has been the biggest obstacle. When Nevada Senator Harry Reid became US Senate majority leader in 2007, the project was effectively put on indefinite hold. With renewed interest in nuclear expansion, the Department of Energy (DoE) is again considering alternatives. It has identified sites in Utah, Idaho, Louisiana, Oklahoma, and Tennessee, though Yucca Mountain remains the only legal option for permanent disposal for now. The source says the United States has accumulated around 95,000 metric tonnes of nuclear waste over the years, underscoring the scale of the challenge.
Several deep geological repositories are expected to begin operating in different countries over the coming decades, while scientists continue to explore alternative waste-management approaches. But if governments want to expand nuclear generation, the waste question will have to be addressed alongside the build-out of new reactors.
