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Olkiluoto waste dump: Deadly legacy under the Baltic Sea
A permanent storage site for high-level nuclear waste is planned on the island of Olkiluoto, Finland. There is no
operating permanent waste dump for high-level civilian waste anywhere in the world. The plan is based on the
KBS-31 concept coined by Swedish nuclear industry in early 1980s based on 1970s research. The model has
stayed fundamentally unchanged since then and has been copied as such into Finland. A proposed location for
a KBS-3 type waste dump was identified by the industry in 1999 in Finland and in 2009 in Sweden. Neither
country has granted a permission to build a nuclear waste storage site. In Finland, the industry is undertaking
required research in order to be able to submit a construction permit application in 2012. The company is
targeting start of operation in 2020. In Sweden, the industry aims to start dumping high-level waste in 2023.
The KBS-3 method is designed for hard rock, immersed in groundwater. The method relies on man-made
artificial barriers to isolate the nuclear waste from the environment. The plan is to pack the waste in cast iron
inserts in copper canisters and place them in holes bored in tunnel floors, surrounded by bentonite clay. The
repository tunnels are intended to be at a depth of about 400-500 metres. None of the barriers will last
forever; the industry attempts to show that they can be trusted to last "long enough" in order to graduate the
radioactive contamination and delay it until the radiotoxicity of the waste has been sufficiently reduced. This is
generally taken to imply a time period of hundreds of thousands of years.
The criteria used by Finnish authorities are far too lenient - even relatively low residual doses of radiation to a
small population can cause substantial mortality, when sustained over incomprehensibly long periods of time.
Regulation in Finland only requires the industry to demonstrate that exposure to radiation is below 0.1 mSv/a
per person during the first 10 000 years.
There are enormous uncertainties and gaps in knowledge in regard to the failure mechanisms and rates of the
barriers, many raised even by scientific reviewers commissioned by the national nuclear watchdogs.
How the barriers can fail
Corrosion, erosion and mechanical stress can cause the artificial barriers to fail much faster than
anticipated. Recent studies by Swedish Royal Technical University have demonstrated, that copper can
be corroded in the absence of oxygen at a 1000-fold faster rate than the industry assumes. As a result,
the 5cm thick copper capsules could be breached in less than a millennium2. During the first centuries,
the waste remains very hot, speeding up the failure of all artificial barriers even by orders of
magnitude. Worst-understood corrosion mechanisms include electrochemical corrosion and stresscorrosion cracking. Prolonged exposure to high temperatures will affect the properties of the bentonite
clay in unknown ways3. The bentonite buffer can be eroded by groundwater and the process is poorly
1
KBS refers to the Swedish words for "nuclear fuel safety".
Hultquist, G. et al. (2009). Water Corrodes Copper. Catalysis Letters, Volume 132, Numbers 3-4.
http://dx.doi.org/10.1007/s10562-009-0113-x
3 W.E. Falck and K.-F. Nilsson (2009). Geological Disposal of Radioactive Waste: Moving Towards Implementation.
Reference Report. European Commission Joint Research Centre, p 13.
http://ec.europa.eu/dgs/jrc/downloads/jrc_reference_report_2009_10_geol_disposal.pdf
2
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understood4. Chemical reactions and other interactions between substances in cement, steel,
bentonite, groundwater and host rock are poorly understood5.
Some of the thousands of waste canisters will most likely have manufacturing defects or get damaged
during deposition and backfilling6. Thus, radionuclides will start spreading into the surroundings
immediately, as will generation of hydrogen from the corrosion of steel. There can be rapid release
pathways for migration of radionuclides to the surface, including unidentified cracks in the bedrock and
damage caused to the bedrock during excavation. Complete identification of cracks and groundwater
flows in the bedrock is very demanding or next to impossible7.
Human intrusion into a KBS-3 waste dump could have catastrophic consequences, either by removing
the barriers or by enabling the use of the waste for dirty bombs or atomic bombs. After large scale use
of civil and military nuclear technology has come to an end, nuclear waste will remain the most
accessible source of material for nuclear weapons. The waste dump also contains large quantities of
scarce raw materials, such as copper and steel. Communicating the contents of the waste dump to
future civilizations is a virtually impossible task.
Scandinavia will experience at least one ice age during the next 100 000 years. Ice ages entail
extremely strong earthquakes caused by changes in the enormous mass of over a kilometer-thick ice
sheet.8 Fault lines caused by these ice ages are also found in the proximity of the proposed waste dump
sites. Permafrost, earthquakes and intrusion of fresh, oxygen-containing water will breach what is left
of the man-made barriers. In the worst case, a new fault line will cut through a nuclear waste dump,
completely obliterating all barriers at once and providing a direct release route for waste to the
surface. The massive movements of water, soil and ice associated with ice ages will spread radioactive
contamination over large tracts of land and water, making any clean-up impossible.
The Finnish nuclear watchdog has commissioned an evaluation of the Finnish waste management company
Posiva's research on long term safety of the waste depository from professor Matti Saarnisto, Secretary
General of the Finnish Academy of sciences and former head of the Finnish Geological Survey. According to
Saarnisto, “the huge downward and upward movements [of the bedrock] are one of the main risks of the
nuclear waste depository together with glacial loading and permafrost, but they are not addressed in adequate
detail in the report. […] All predictions of depository safety beyond the next glaciation […] are speculation and
not based on scientific facts. […] During the next 120 000 years the depository will be covered by a continental
4
Swedish Nuclear Power Inspectorate (2008). SKI:s yttrande och utvärdering av SKB:s redovisning av Fud-program 2007.
http://www.stralsakerhetsmyndigheten.se/Global/Publikationer/Rapport/Avfall-transport-fysiskt-skydd/2008/SKI-FUD2008-48.pdf
5
W.E. Falck and K.-F. Nilsson (2009). Geological Disposal of Radioactive Waste: Moving Towards Implementation.
Reference Report. European Commission Joint Research Centre.
http://ec.europa.eu/dgs/jrc/downloads/jrc_reference_report_2009_10_geol_disposal.pdf
6
The Finnish nuclear waste company Posiva has assumed the defect rate to be one in a thousand canisters, see Vieno, T.
& Nordman, H. 1999. Safety assessment of spent fuel disposal in Hästholmen, Kivetty, Olkiluoto and
Romuvaara TILA-99.Posiva Oy, Helsinki, Finland. Posiva Report POSIVA 99-07. Later, testing has shown that significant
thinning could occur during manufacturing in one in a hundred canisters, see Pastina, B. & Hellä, P. (2006). Expected
Evolution of a Spent Nuclear Fuel Repository at Olkiluoto. Posiva.
7 W.E. Falck and K.-F. Nilsson (2009). Geological Disposal of Radioactive Waste: Moving Towards Implementation.
Reference Report. European Commission Joint Research Centre.
http://ec.europa.eu/dgs/jrc/downloads/jrc_reference_report_2009_10_geol_disposal.pdf
8
Matti Saarnisto 2008: Evaluation report on the Posiva report 2006-5. STUK, available on demand.
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glacier or the Baltic basin waters for some 40 000 years without any possibility to control it.” Saarnisto also
remarks: the “sections which I have evaluated have been written by a person/persons with inadequate
knowledge and in some sections are based on elementary books or poor-quality reports.”8
From barrier failure to environmental contamination
Both in Finland and Sweden, the proposed sites are on the coast of the Baltic Sea, partially directly under the
surface of the Baltic Sea, at a depth of 400-500 m. At this depth, groundwater flows through the dump and
towards the sea. This means that when the waste dump starts to leak, radionuclides will reach the sea in 50100 years9.
Estimates of radionuclide solubility in groundwater and migration rates in the bedrock have enormous
uncertainties and are based on poor-quality data. Most chemical research on e.g. uranium and plutonium has
been carried out under conditions, including but not limited to temperature, that are ‘far from those occurring
in nature'. Of particular relevance for the Finnish and Swedish projects is lack of data on the behavior of
radionuclides in salty water. 10,11
Bentonite clay can be a particularly problematic choice of buffer, as it forms colloids that bind poorly soluble
radionuclides. These colloids are not readily adsorbed by bedrock and can therefore be easily transported in
groundwater.12,13 This greatly increases the amount of waste that reaches the biosphere.
Some of these uncertainties and gaps could be redressed by prolonged experiments in conditions mimicking
those expected to prevail in the waste dump; first of these experiments only got underway in the late 1990s
and the results so far do not support modeled long-term behavior of copper and clay. The industry claims they
can address the uncertainties by using conservative estimates. However, the gaps in knowledge are often large
enough to render any guess as good as the other and hence the entire concept of a conservative estimate lacks
meaning14.
9
Björn Dverstorp (2007). SSI:s granskning av SKB:s storregionala grundvattenmodellering för östra Småland (SKB Rapport
06-64). Swedish Radiation Protection Authority.
10 IAEA (2007). Spent Fuel and High Level Waste: Chemical Durability and Performance under Simulated Repository
Conditions Results of a Coordinated Research Project 1998–2004. IAEA-TECDOC-1563. http://wwwpub.iaea.org/MTCD/publications/PDF/te_1563_web.pdf
11 W.E. Falck and K.-F. Nilsson (2009). Geological Disposal of Radioactive Waste: Moving Towards Implementation.
Reference Report. European Commission Joint Research Centre, pp17-18.
http://ec.europa.eu/dgs/jrc/downloads/jrc_reference_report_2009_10_geol_disposal.pdf
12
Alonso, U. et al (2007). Bentonite colloid diffusion through the host rock of a deep geological repository. Physics and
Chemistry of the Earth, 32:469-476. http://dx.doi.org/10.1016/j.pce.2006.04.021
13 W.E. Falck and K.-F. Nilsson (2009). Geological Disposal of Radioactive Waste: Moving Towards Implementation.
Reference Report. European Commission Joint Research Centre, p 20.
http://ec.europa.eu/dgs/jrc/downloads/jrc_reference_report_2009_10_geol_disposal.pdf
14 See e.g. “Using Thermodynamic Sorption Models for Guiding Radioelement Distribution Coeffient (Kd) Investigations –
A Status Report”. http://www.oecdbookshop.org/oecd/display.asp?sf1=identifiers&st1=662001061P1
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Baltic sea
Olkiluoto
waste dump
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Figures 3 and 4: The proposed waste depository in Olkiluoto is located less than a kilometer from the Baltic sea, in a
place where the groundwater flows from the bedrock directly into the sea.
800
m
Waste
storage
site