Ever since the first nuclear power plants were constructed in the 1950s, the world has been trying to figure out how to dispose of the highly dangerous by-product from these plants.
As of 2015, the world had 270,000 tons of used nuclear fuel stored in temporary above-ground sites in underwater ponds at nuclear power stations. But Finland thinks it has found the answer to safely storing its spent nuclear fuel, by burying it deep within the bowels of the earth in a specially-built repository.
Off Finland’s west coast is the little island of Olkiluoto. Lush and green, no one would suspect that this serene landscape will house some of the deadliest waste in the world. The island is already home to one of two of Finland’s nuclear power plants and is now the site of a massive tunneling project expected to have operational costs for 100 years of up to 3.5 billion euros ($4 billion) until the 2120s, when the tomb will be sealed for good.
“This has required all sorts of new know-how,” said Ismo Aaltonen, chief geologist at nuclear waste manager Posiva, which got the green light to develop the site last year. Actually, the project began in 2004 with the building of a research facility used to study the feasibility of using the island’s bedrock for storage of nuclear waste.
Starting in 2020, Finland plans to start storing 5,500 tons of nuclear waste in the tunnels of Onkalo, more than 420 meters (1,380 feet) below the surface of the Earth.
Today, the repository consists of 15 kilometers (9.3 miles) of tunnels with three shafts for staff and ventilation. When the warren is finished, it will consist of 42 kilometers (26.1 miles) of tunnels going deep within the Earth. The temperature in the underground warren is cool, and the bedrock is extremely dry. This is important in protecting the spent nuclear rods from the corrosive effects of water, according to Phys.Org.
Safety questions over storage of spent nuclear fuel
Engineers at Posiva have been studying the best ways to seal the fuel rods to keep them safe. They expect the fuel rods to have lost most of their radioactivity after a few hundred years, but their plans call for storing them for at least 100,000 years, says the Times of India.
The plan is to place the spent fuel rods in iron casts, then seal them into thick copper canisters before lowering them into the tunnels. Each canister will be surrounded by a buffer of bentonite, a type of clay that should protect the rods from shuddering in the surrounding bedrock as well as act as a protection from any water seepage.
Additionally, clay blocks and additional bentonite will be used to seal up the tunnels before closing the repository for good. Posiva says this method was developed in Sweden and insists it is very safe. As a matter of fact, Sweden has a similar project underway now.
Opponents of the project have their say
Nuclear power opponents, like Greenpeace, are raising concern over the possibility of radiation leaks. “Nuclear waste has already been created and therefore something has to be done about it,” said the environmental group’s Finnish spokesman Juha Aromaa. “But certain unsolved risk factors need to be investigated further.”
Greenpeace contends that we are asking ourselves a question that is impossible to answer. How can we know what the island will be like in 100,000 years, and who will be living there? Furthermore, geologists cannot rule out another ice age. While Finland is not particularly seismically active, Greenpeace wants geologists to ensure that Onkalo can withstand any tectonic pressure brought on by an ice age.
Actually, a study done in 2015 by researchers at the University of Turku warned that in the event of a new ice age, the permafrost could reach some 200 meters or more below where the rods would be buried. Posiva’s research claims that in the scenario mentioned in the study, the rocks could fracture, but not as far down as the rods would be buried.
This argument alone was enough for the Finnish nuclear authority to demand additional modeling on the possible long-term effects of a prolonged freeze.
Should the waste repository be advertised?
After the repository is sealed with giant concrete plugs, the question remains, should there be a sign warning people about what the site contains? Some people are wondering about future inhabitants, and should we have a warning in place as to what dangers lurk beneath the concrete plugs.
Posiva is pondering this question, wondering if the site should be landscaped to look as if nothing is there. A spokesman said, “It is still being discussed if the place should be marked with warning signs.”
Regardless, Olkiluoto’s current residents have grown used to having a nuclear waste dump in their backyards. One local farmer, Timo Rauvola appears to have grown very nonchalant about the whole business. “Personally, I believe that when (the waste) is placed deep down there with care and expertise, it is better than how it is now around the world — placed wherever.”
