Best forgotten

Written by  Martin Arnold

Sweden and Finland have come very far in the search for a final disposal site for high-level radioactive waste. In Finland, it is already being built.


In southeast Sweden, just opposite the island of Gotland, is the Äspö Hard Rock Laboratory in Oskarshamn, which was opened in 1995.  The bedrock here consists almost entirely out of granite. It is more than a billion years old and has less tectonic activity that in the Alps. But the granite often includes other rock formations, and water flows through tiny cracks. The scientific experiments conducted in the rock laboratory should provide answers to questions such as: Are there shifts in the rock? Does water break through? What are the pressure conditions like? Are there gas pockets? How does the rock react to heat? Because granite is more permeable than clay, Sweden opted to use expensive copper in the containment vessels to protect against the risk of corrosion. One copper canister is five metres long and weighs over seven tonnes. When filled, it weighs 25 tonnes. Inside of it the fuel rods are covered with steel and the whole is then encapsulated with copper. At today's global market prices, the copper used would have a value of between 300 million and half a billion euros. But the value of this commodity could still rise and extracting it in the distant future could be a reason to retrieve the dangerous stored materials. With Östhammar, located near the Formark nuclear power plant, Sweden as approved a site for a deep repository for high-level radioactive substances on communal land, particularly as there is already a final disposal facility here for low- and intermediate-level radioactive waste. The population mostly sees the economic advantages because it has created new jobs. In addition, per capita consumption of electricity in Sweden is double that of Switzerland, and the country has a long tradition in nuclear technology. The disused fuel rods from Oskarshamn are located in a central interim storage facility called Clab until they can be sent to a permanent deep repository. In Clab, which stands for "central holding storage for spent nuclear fuel", the fuel rods are placed around 40 metres under the Earth's surface, safe from earthquakes, in massive cooling tanks with 40,000 cubic metres of water and a capacity of 8,000 tonnes. Unlike in other countries where the fuel rods are packed in castor in an interim storage facility as they await final disposal, the fuel rods in Sweden are cooled for 30 to 40 years in a wet storage facility.
Although the granite in Östhammar has fewer inclusions that elsewhere, thus making it more compact, water permeation over the next thousands of years cannot be entirely ruled out. That's why Sweden opted for copper and why an individual chamber is being drilled for every single cannister – just as may someday be done in Switzerland and other countries. It is still unclear if the final resting place will be situated horizontally or vertically. When the container is stored there, the chamber is filled with bentonite, a special lava ash that prevents water over a certain period from coming in contact with the copper casing. A final decision on the permanent disposal site is likely to take place in 2017, allowing the repository to go into operation by 2029 according to Swedish plans.
Hope as passive monitoring
The SKB in Sweden works closely with its Finnish counterparts. Its Scandinavian neighbour is ever further ahead in building a deep repository for high-level radioactive waste. More accurately: it is already long under construction. The access ramp is mounted, but inside the tunnel after around a dozen right turns, which twist their way down into the Earth to a depth of around 440 metres, the tunnel is not yet coated. Apart from the actual access tunnel, there are of course ventilation shafts, demonstration tunnels and rooms for technical equipment. Together with all the secondary shafts, the tunnel is nearly 10 kilometres long. Above ground are offices, encapsulation facilities, cleaning and repair facilities, a research station as well as buildings for the tunnel technology. Onkalo on the island of Olkiluoto was selected from 100 sites and is expected to go into operation in 2020.  No other country in the world has come this far. Posiva plans to store the radioactive waste starting in 2020 and will continue for 100 years, after which time the storage facility will be closed and in the best case will be forgotten about. The name says it all: in Finnnish, Onkalo means "hiding place".


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Cutting of the Documentary "Into Eternity" (2010)