Nuclear waste storage may be less problematic and dangerous than we tend to imagine, but that is not to say that it does not involve serious headaches and enormous precautions. And in this fight to make waste safer, deep geological storage seems to prevail as a strategy.
Deep geological storage. This way of storing nuclear waste is based on a very simple idea, that of burying it far below the surface. With this, deep geological storage (AGP) seeks to avoid some of the problems generated by more “shallow” storage.
Problems such as the cost derived from surveillance, not only before possible incidents but also against the possibility of material theft. Although shallow storage may be cheaper in the short term, this need for constant maintenance makes it a more cost-effective option.
More than just a graveyard. It is not worth burying them in any way, obviously. The key to this storage lies in finding secure repositories. This depends on the geological conditions. So that the warehouse does not generate problems, it must be located in a stable geological formation.
Warehouses of this type combine the natural barrier provided by the geological formations surrounding the AGP with artificial barriers created during its construction. The objective is to isolate the content properly and ensure that, even in the event of an accident, any release would be small enough to cause no impact.
Another fundamental factor in the AGPs is the management of the heat emanated by the residues. These can radiate their energy in the form of heat, so the warehouse must make it easier for it to dissipate without affecting its operation or the waste stored in it.
Additional security measures. The operation of these warehouses is complementary to the security measures that are commonly used in the treatment of waste, such as the use of specific containers for the storage of this type of waste or the passage of a certain period of time of “cooling” beforehand. the transfer of waste to its final resting place.
Onkalo, un precedent en Europa. The first warehouse of this type in our environment is being built in Finland. Onkalo, which can be translated as “cave”, is 430 meters deep (the repository will be 420 meters below sea level). According to plans, the repository will remain open for about 100 years and will gradually accept new radioactive waste. After that it will be permanently sealed for the next 100,000 years.
Onkalo is not the only project in its class. In neighboring Sweden, preparations are advancing for the construction of such a warehouse. Also France could open one in the coming decades. Outside of Europe, Canada is preparing to do the same and the United States already has a warehouse with similar characteristics for radioactive material for military use.
And in Spain? At the end of last year the Government and the Nuclear Safety Council approved the creation of a decentralized network of warehouses for nuclear waste. These warehouses would be used to temporarily house the nuclear waste from the seven active reactors in the State.
The plan also includes the creation of an AGP as a final resting place for this waste. We will have to wait until we get to this point. Until 2073. Although the plan contemplates the creation of this storage system, it does not foresee its entry into operation for another half century.
He who cleans a lot is not clean… The long-term objective involves technologies that generate less waste. Fusion power is a form of nuclear energy that does not create hazardous waste. This is based on the fusion of isotopes of hydrogen into helium. This implies that the process does not generate, in essence, hazardous waste.
Fission energy also has room for improvement. Today most of the fuel used by nuclear power plants goes to swell the mass of waste it generates. This is because current plants can only use a fraction of the fuel.
There are technologies that will allow us in the future to make better use of uranium resources. Examples of this are molten salt and thorium reactors. The latter have residues with a considerably shorter half-life than those generated by current plants. We know the technology, but there is still a long way to go until it is profitable. Until then we will have to plan what to do with our waste. The AGP are the best asset we have today.
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