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Geology and nuclear waste in Finland

Nuclear Monitor Issue: 
Janne Björklund, Finnish Association for Nature Conservation

The issue of final disposal of used nuclear fuel has not yet been resolved. Use of nuclear power includes a difficult moral question: do we have the right to make use of uranium resources and just leave the resulting waste for the next thousands of generations to worry about? Finland, together with Sweden, are internationally often seen as countries close to a final disposal facility.

In Finland, the legislation now forbids the export of nuclear waste. The plan is to use bedrock of Olkiluoto - site next to a nuclear plant - for final disposal. On this process, the key issue is the long-term safety. Spent nuclear fuel is maybe the most dangerous material which exists. There is not a permission to build or use an end-disposal site anywhere, the Finnish company Posiva has only a test-permit at the moment. Several years of research are still needed before even an application of the final disposal site can be posted.

Bedrock in Olkiluoto is full of cracks, because of the location. During a future ice-age, as it did in the past, the glaciers extend fully in top of Olkiluoto island. This creates heavy earthquakes, rifts and cracks to the bedrock.

Mostly this site was choosen because of political reasons, it is next to a nuclear power plant and the local people are not so much against the final disposal site. There were other candidates also, but those created a lot of local resistance.

A survey commissioned by the STUK – the Finnish Radiation and Nuclear Safety Authority - has estimated the long-term safety of the Posiva project. According to this survey by professor in geology Matti Saarnisto, long-term safety of the final disposal site is speculative and is not based on scientific facts. Professor Saarnisto has been a research professor at the Finnish Geological Survey and the Secretary General at the Finnish Academy of sciences.

First of all, the depth to which permafrost can extend during an ice age has been incorrectly estimated. Permafrost can cause massive pressure on the end-disposal capsules and crack them. Posivas estimates the depth of the permafrost a bit over 180 meters. According to professor Saarnisto, the same kind of mathematical models have been used in Canada and the result have been about 700 meters. One can ask, why Posiva doesn't plan to put the final disposal site deeper, f.e.800 meters? Answer can be, that the structure of the bedrock on that depth is so inconvenient that the implementation is very expensive or even impossible.

The reversibility and monitoring of nuclear waste are impossible to realize, as the nuclear waste site will be either partially or wholly submerged in water or continental ice for most of the timeframe being examined. Long-term safety for the site means several hundreds of thousands of years. Professor Saarnisto wrote: 'somewhere in the next 120 000 the depository will be covered by a continental glacier of the Baltic basin waters for some 40 000 years without any possibility to control it'. The controllability and reversibility is anyway needed - if something goes wrong, the nuclear waste capsules need to be returned to the surface.

The prediction of earthquake occurrences is inadequate, according to professor Saarnisto. Huge downward and upward movements of the bedrock are one of the main risks of the depository, together with glacial loadings and permafrost. Posivas report of long-term safety does not deal with these issues properly. Posiva notes that a single breakup of a capsule wouldn't have environmental effects, but this position is presented without arguments.

Several depository sites all over the world have run into serious trouble and the projects have been terminated. What to do with the nuclear waste if end disposal in bedrock seems to be impossible to operate? First of all, we should stop producing more of it..

Further reading:

  1. The decision in principle by the Government concerning Posiva Oy's application for the construction of a final disposal facility for spent nuclear fuel produced in Finland. 2001.
  2. Matti Saarnisto 2008: Evaluation report on the Posiva report 2006-5. Radiation and Nuclear Safety Authority(STUK). available on demand from STUK.
  3. Posiva (2008): Expansion of the Repository for Spent Nuclear Fuel. Environmental Impact Assessment Report.
  4. Expected Evolution of a Spent Nuclear Fuel Repository at Olkiluoto (Revised October 2007) December 2006, Posiva

Source and contact: Janne Björklund, nuclear campaign coordinator, Finnish Association for Nature Conservation