The war in Ukraine showed the risks of surface storage of radioactive waste.
Enough to reassure Switzerland, which wants to bury its high-level waste deep underground, the project is at a crucial turning point.
“We are at a depth of 300 meters in an excavated laboratory” to study the burial of radioactive waste in clay,” explains geologist Christophe Nussbaum, head of the Mont-Terry international laboratory, near Saint-Ursanne in the canton of Svor.
Three sites in the northeast of Switzerland, near Germany, compete to receive this waste.
Plant operators are expected to announce their preferences in September. The government will make a decision in 2029, but opponents can hold a referendum.
The center of Mont-Terry is actually made up of 1.2 km of galleries dug into the rock.
The niches, whose walls are about 5 meters high and stabilized with shotcrete, house various storage simulations thanks to a small amount of radioactive elements monitored by thousands of sensors.
More than 170 experiments were carried out to simulate the various stages – disposal of waste, closing of galleries, monitoring – and reproduce every imaginable physical and chemical effect.
– 8000 generations of people –
Experts estimate that it takes about 200,000 years – or about 8,000 human generations – for the radioactivity of the most toxic waste to return to its natural level.
But the researchers, Mr. Nussbaum points out, are analyzing a repository that is estimated to have a duration of about “a million years, since that’s the duration that needs to be safely contained.” So far the results are positive.
Switzerland is moving too fast for Greenpeace. “There are a lot of unresolved technical issues: it is a guarantee that the system will not lead to the release of radioactivity in 100, 1000 or 100,000 years,” Florian Kasser, in charge of the nuclear NGO, tells AFP. questions.
“We are putting the cart before the horse because, without having solved a lot of questions, we are looking for sites,” he continues, suggesting that Switzerland also needs to first decide how the site will be reported, so as not to be forgotten and so that generations of centuries will come, knowing about danger.
– Horizon 2060 –
In Switzerland, radioactive waste has been produced in power plants for more than 50 years and is managed by the National Cooperative Society for the Storage of Radioactive Waste (Nagra), founded in 1972 by nuclear power plant operators and the Confederation.
For the time being, they are in an “intermediate warehouse” in Würenlingen, about 15 km from Germany.
Very few countries are at an advanced stage of deep geological burial. Only Finland built a site (in granite), and Sweden at the end of January gave the go-ahead for waste disposal, also in granite.
Then comes France, whose Cigeo project, piloted by the National Agency for Radioactive Waste Management (Andra), plans to store radioactive waste underground at Bure (Meuse), in clayey rock. “We are waiting for a declaration of public utility and at the same time we will apply for a building permit,” Andra spokeswoman Emily Grandidier explained during a visit to Mont Terri.
After the accident at the Fukushima nuclear power plant, Switzerland decided to phase out nuclear energy, but gradually: four used reactors can be used as long as the power plants are safe.
Approximately 83,000 m3 of radioactive waste, including a small portion of high-level radioactive waste, must be disposed of. This volume corresponds to the scenario of a 60-year operation life of the Beznau, Gösgen and Leibstadt nuclear power plants, as well as 47 years of the Mühleberg plant closed at the end of 2019.
Work on the landfill should begin by 2060.
“This is the project of the century: for 50 years we have been doing scientific research, and now we have 50 years to approve and implement the project,” said Felix Glauser, a spokesman for Nagra.
The monitoring period will span several decades before the site closes in the next century.