Onkalo (or ‘cave’) is being dug into the bedrock near the Olkiluoto power station by Posiva, which is 60 percent owned by TVO and 40 percent by Fortum. The latter utility owns two commercial reactors in Loviisa on the south-east coast, and has applied to build a third. TVO has two operating reactors on Olkiluoto, an island in the municipality of Eurajoki, on the west coast between Rauma and Pori.
Finland is the first country in the world to attempt to build a safe permanent storage place for nuclear waste, at an estimated cost of some three billion euros. Similar repositories are planned in Sweden – where this so-called multi-barrier deep geological disposal system was devised – and France, but construction has not begun.
In the meantime, most of the world’s spent fuel rods are being temporarily stored in tanks of water – a practice being increasingly called into question since last spring’s Fukushima disaster. There are now some 1900 tonnes of high-level nuclear waste being held in interim storage in Finland.
Do the math
TVO is building a third nuclear power production unit (OL3) and has received the green light from the government for a fourth (OL4). Meanwhile Fortum has two at Loviisa, and hopes to build a third there someday. However that is unlikely to be approved during the current legislative term at least.
In effect, the companies are planning to make Onkalo only large enough for waste from their own potential seven reactors – and are counting Fennovoima’s already-approved one as Finland’s eighth.
Spent fuel from the Fortum and TVO plants will have to be stored for 40-60 years before it cools enough to be stored underground. As the oldest Finnish reactors have been in operation since the late 1970s, some of their waste will soon be old enough for encapsulation.
Speaking to YLE journalists last week, Posiva President Reijo Sundell reiterated that there is no possibility of also using the repository to store spent fuel from Finland’s sixth reactor. It is to be built by a newly-formed consortium, Fennovoima, in Pyhäjoki on the upper part of Finland’s west coast. Last week a court removed the last legal obstacles to those site choices.
TVO offers to share know-how
The Nuclear Energy Act revision of 1994 requires nuclear power plant operators to arrange permanent disposal of nuclear waste within the country. The radioactive waste from Finland’s nuclear plants cannot be exported. Fennovoima has asked for permission to use Onkalo, but been rebuffed by TVO and Fortum.
“We’re not trying to be nasty,” said Sundell on Wednesday. “But the simple fact is that there is not enough room. We can’t expand the site under the sea. We can’t create another deeper level because then it might not withstand the pressure of an ice age. And we can’t build a shallower level because the underground water there is saltier and therefore more corrosive.”
“However we would be happy to share our know-how,” he added. “There are many other places in Finland where there is bedrock suitable for building a similar repository.”
Posiva is to formally apply for planning permission to build the storage area of the repository next year. Permanent disposal of radioactive waste at Onkalo is to begin in 2020 and be completed about a century later. The material is to be sealed in copper canisters and surrounded by bentonite clay in a labyrinth of tunnels extending 420 meters underground.
OL3 online in 2013
This depth was reached in June 2010, and commemorated in a ceremony led by then-Minister of Economic Affairs Mauri Pekkarinen. However it will take decades for the entire network of tunnels to be completed.
Meanwhile OL3, which will be the world’s largest nuclear power reactor, remains far behind schedule and over budget. It was originally to have begun operations in 2009. TVO project director Jouni Silvennoinen said in September that fuel will be loaded next autumn, with commercial operations to begin roughly a year after that. Since then, however, TVO has announced another year's worth of delays, pushing the start-up back to 2014.
Also in September, the Rauma newspaper Länsi-Suomi reported that the Finnish Radiation and Nuclear Safety Authority (STUK) has identified safety concerns at operating Finnish power plants as part of stress tests conducted after last spring’s Fukushima crisis in Japan. These include the lack of backup cooling systems that are independent of electrical supply at the Olkiluoto1 and 2 reactors.
Guaranteed for 100 millennia?
The Onkalo project is best known internationally because of Danish filmmaker Michael Madsen’s 2010 documentary Into Eternity, which earned more than a dozen awards at film festivals worldwide. Experts interviewed for the film expressed doubts as to whether the repository can really remain undisturbed for 100,000 years – which is some 10 times longer than any structure made by humans has so far lasted. It also raises the tantalising question of whether, and how, future generations of humans – or anyone else – should be warned to stay away from the site.
Such long-term questions about the plan have been raised by experts such as Geology Professor Matti Saarnisto, former Secretary-General of the Finnish Academy of Science and Letters, who studied the plan for the nuclear safety watchdog STUK. In June 2010 he told Parliament that “an exaggeratedly positive image has been presented of the integrity of the structure of Olkiluoto’s bedrock”. He warns that a honeycomb of storage sites extending over an area of several square kilometres will weaken the bedrock, making it vulnerable to earthquakes, and that during an ice age permafrost could spread deep into the rock, potentially rupturing the canisters and releasing radioactivity into the groundwater.
In short, it is difficult for anyone to guarantee that none of these will occur during the estimated 100,000 years that it will take for the radioactivity level of the waste to decline to non-hazardous levels.
CORRECTION: The statement in the video clip attributed to Jouni Silvennoinen of TVO was made by Posiva's Reijo Sundell.