Sweden has radioactive waste. Most of it comes from nuclear power, but some also comes from medical care, industry and research.
It is Sweden's common responsibility to deal with this waste. We must not pass it on to future generations, but manage and dispose of it today.
The responsibility of doing this falls upon those who produce the nuclear waste in question, according to a law promulgated by the right-wing government in 1977. To deal with this requirement, the Swedish nuclear industry formed the company SKB (Swedish Nuclear Fuel and Waste Management Co). An extensive research program was begun to find and implement an optimal solution for the Swedish nuclear waste problem.
SKB's mission is to manage and dispose of radioactive waste from the Swedish nuclear power plants. But we also manage other types of radioactive waste. Work is currently under way to find a site for disposal of the spent nuclear fuel - a final repository.
The final repository.
But before we look at the final repository, the facility most people associate with nuclear waste, let us look at the other facilities of the SKB.
While not really a facility, the first thing SKB procured was the custom built nuclear waste ship m/s Sigyn.
m/s Sigyn was launched in 1982 and transports all Swedish nuclear waste between the nuclear power plants and the relevant SKB facilities. As all the nuclear plants are on the coast and have their own dedicated harbours, waste transports are much less of a hassle and controversy than it is in for example the US and Germany where waste is shipped by truck and train.
Low and intermediate level nuclear waste (such as contaminated tools, clothes, pipes, water purification filter resins and also waste from industry and health applications) are transported to SFR (Final repository for radioactive operational waste). SFR is located 55 metres below the bottom of the sea and is accessed from a tunnel opening on the edge of the vast man-made cooling lagoon outside Forsmark nuclear power plant (in which it's damn nice to bath in the summer as the water is 30 degrees hot).
SFR outside Forsmark.
The waste is sorted and compressed. The low level waste is put in containers while the intermediate level waste is mixed with concrete and encased in square boxes of steel or concrete which are put in the three repository tunnels (4, 5, and 6 below). After 500 years the radioactivity of the intermediate waste has fallen to the same level as the surrounding rock, for low level waste the time required is 50 years.
Rock tunnel in SFR.
Originally it was thought the current SFR would not be large enough to hold all low and intermediate level waste that will be generated in Sweden, so the facility was constructed to be easily enlarged if needed (observe the three unfinished tunnels opposite 4, 5, and 6). Better waste sorting means that this will not be necessary.
The below ground facilities of SFR.
Now onto the thing that tend to worry people the most, spent nuclear fuel. Nuclear fuel consist of small black pellets of uranium dioxide which are stacked into vertical fuel rods in fuel assemblies. Each assembly contain many fuel rods.
Pellets, fuel rod and a 4 metres long fuel assembly.
The fuel spends 5 years inside the reactor core until it is spent. It is now intensely radioactive and also gives off lots of heat. To make it easier to deal with it, the spent fuel is stored at the nuclear power plant for one year in cooling ponds filled with water. After one year 90 % of the radioactivity has diminished and the fuel is put in special transportation casks, loaded onto m/s Sigyn and shipped to Clab.
m/s Sigyn at work.
Clab (Central interim storage facility for spent nuclear fuel) is where all Swedish spent fuel currently ends up, and this has been the situation since 1985 when Clab was completed.
Clab is located next to Oskarshamn nuclear power plant and houses vast, deep cooling pools blasted from the rock at a depth of 30 metres below the ground.
The water effectively shields the rest of the rock vault from radiation.
In these pools the spent nuclear fuel is stored for 30-40 years to cool and let the radioactivity diminish further. After the stay in Clab the radioactivity of the fuel has subsided to about 0,5 % of the levels it had when it was brought fresh out of the reactor.
Spent fuel at the bottom of a pool.
Couldn't we just let the spent fuel stay in Clab while we await some future technology that can help us deal with it (like transmutation)? In theory, yes. This is known as the "zero alternative".
A study was conducted in 2000 concerning continued storage in Clab [...]. The results showed that Clab can, with reasonable maintenance, be operated in a safe manner for a hundred years or more and that the spent nuclear fuel can be stored for even longer.
But this is not a very good or responsible idea.
No one knows what society will look like in the future
Thus, as long as we have the society we have today, we can assume that it will be possible to continue to operate Clab safely for 100 years or more. But if Clab has to be abandoned, due for example to war or environmental disasters, the consequences may be serious.
Another serious consequence of the zero alternative is that the competence that exists today concerning the planned system for final disposal might be lost. In the meantime. The competence in the nuclear waste field currently possessed by regulatory authorities, nuclear power utilities, SKB, universities and consultants will dissipate. The necessary enthusiasm, overview and expertise exist now. To risk wasting these resources is not a good alternative.
Moreover, indefinite interim storage is contrary to Swedish law. And according to international agreements, the nuclear waste must not burden future generations.
So, something must be done. This something is known as the deep, or final, repository. At the present, it doesn't exist. But that situation is about to change.
Since the seventies SKB has been investigating the Swedish bedrock. In 1986 the Äspö hard rock laboratory was constructed. It is in effect a miniature of the future repository. Many experiments on the repository technology have been made here and it has become an international center of nuclear waste repository research.
Äspö HRL above ground and below.
In the early nineties the knowledge had become so good SKB decided to start looking for a number of candidate sites. Four sites were chosen. Of these, two decided in municipal referendums that they would not host the repository. The two remaining sites were, not very surprising, Oskarshamn and Östhammar, municipalites that both host nuclear power plants (Östhammar host Forsmark npp). There have been extensive consultation with the local population and the local authorities, without whose support the project would be entirely impossible.
In 2002 SKB began doing site investigations in Forsmark and Oskarshamn. They will be completed in 2007. If the results are favourable (and I have a feeling they are very likely favourable...) an application to build the repository will be filed with the Environmental court and the Government in 2009. Construction will begin in 2011 and finish in 2018. Finland has already begun building its own repository, using the Swedish technology developed at Äspö HRL.
But, what is this technology? How will the repository work, in detail?
The technology is called KBS-3. Basically, the spent fuel bundles are put into iron capsules which are then put into big copper canisters. These copper canisters are then put into holes drilled in the floor of tunnels that are located 500 metres down in the bedrock. After that, the canisters are surrounded by bentonite clay. Bentonite clay swells when it comes into contact with water, stopping the penetration of the water. This is very important as water is what will move the radionuclides if a canister starts leaking. The clay also protects the canisters from corrosion. After the entire complex is loaded with the last of the 4500 nuclear waste canisters, it will be completely filled by bentonite clay. Then the door will be locked and the key thrown away. No surveillance or maintenance will be needed. Ever.
The KBS-3 method.
But is it safe, really? Will it really protect the biosphere from the spent fuel for the next 100.000 years (after which the radiation levels have fallen to the level of natural uranium ore)?
Yes, it is really, really safe. Te repository relies on the defence in depth philosophy. This means that if anything goes wrong, there is another layer of defence. And if that layer also fails there is another and another et cetera.
The first layer is the fuel pellets themselves. They are ceramic and not very prone at all to be dissolved by water.
Nuclear fuel pellets. Each pellet contains about as much energy as three barrels of oil. With breeding that become 200 barrels.
They are encapsulated within the canister. The canister is 5 metres long and has a diameter of 1 metre. Loaded with spent fuel it weighs 25-27 tons. Experiments and research (on for example ancient copper ore in the bedrock and copper cannons that have been in the sea for 300 years) show that the copper canisters should suffer a corrosion of 0,02 mm at best and 4.4 mm at worst after 100.000 years of corrosion. As people like to be on the safe side, it was decided the shell should be 50 mm thick. As long as the canisters are tight no radionuclides will escape. But what if the canisters are penetrated due to some unforeseen event?
Then we get to the next layer of defence, the bentonite clay. The bentonite has three effects. First it protects the canister from geologic movements, due to for example earthquakes. Sweden is in one of the most geologically stable places on the planet, but a future ice age could create earthquakes anyway. The second effect is to protect the canister from water. Without water there is no corrosion. And well, bentonite swells and pushes water away when it gets wet. The third effect is also that it stops water. Without water there is no transport of radionuclides if a canister should be penetrated.
Okay, but what if the fuel is dissolved by water, the canisters are corroded through and radionuclides move through the bentonite in spite of all the safety measures?
Then there are still 500 metres of stone between the biosphere and the spent fuel.
Some people say that plutonuium is an artificial element and hence in some way more "evil" than more natural dangers (bear with me on this one, it's relevant for the subject). As a matter of fact, plutonium is, contrary to conventional wisdom, a natural element. As far as we know, it existed before man. But only once and in a single place.
That place is Oklo in Gabon, where several natural nuclear fission reactors were found. Nature's own plutonium smithy.
Anyway, that was 1.5 billion years ago and what is really fascinating is that the "spent fuel" (the radionuclides) only moved a few metres in all that time. This in spite of the fact that there was lots of ground water sloshing around, in spite of the surroundings being sandstone and not crystalline bedrock, and in spite of the "fuel" not being ceramic and contained within copper canisters. Not to speak of it underwent nuclear fission down there, something our spent nuclear fuel certainly won't do! And in spite of staying there 1.5 billion years instead of 100.000. That's a time factor of 15000. To Oklo's defence, there were lots of clay around, though it's not as good as our bentonite.
1.5 billion year old nuclear reactor core. The yellow spots are yellowcake.
So yes. It's really, really safe.
The cynical among you (and there are a great many) might say, ok this might work, but it won't matter if it's not built due to some corporation's short term greed and reluctance to pay for it all.
That's the beauty of SKB and this Swedish system. It's already payed for. Every kilowatt-hour of nuclear electricity is taxed 0,1 eurocents and put in the (for other purposes) untouchable nuclear waste fund. It currently stands at 4 billion euros (the total cost for the waste program will be about twice that). This fund covers all the cost of all nuclear waste, from the waste research to shipping waste to dismantling the power plants to building the repository. All waste costs are internalised in the price of nuclear power. If coal, oil and gas were forced to do this all fossil power companies and their sucontractors of all kinds in the entire world would swiftly go bankrupt.
Now, some of you are saying, what about breeder reactors? What about the future of nuclear power? What do we do after uranium-235 runs out? The official Swedish answer is that there will be no future of nuclear power as nuclear power is being phased out.
Now, we all know that is bondoggle, but for the sake of the argument let's say no new Swedish reactors are built ever again. In that scenario, the last Swedish reactor will close in 2045 after 60 years of service. Its last fuel will stay in the pools at Clab for a further 40 years and in 2085, at my one hundredth birthday, the repository will be closed and the key thrown away. Until that day we have full retrievability. After that day we have to dig through 500 metres of bentonite clay to retrieve the precious fuel. A lot easier than digging through the 500 metres of bedrock in the first place.
But who seriously believes there will be enough U-235 around in 2085, considering the vast expansion of nuclear power that will likely happen during the 21th century? Long before the repository is full, we will start removing fuel from the repository for reprocessing and breeding.
The Swedish nuclear waste program, the "rolls-royce of nuclear waste programs", is just a big sham. But it's a sham most other countries can only envy.