In Forsmark, Sweden, the decision to bury nuclear waste at a depth of over 500 meters it became a work of art: a network of tunnels It is being opened in the rock to keep spent fuel for up to 100.000 years, at an estimated cost of just over $1 billion …and a timeline that spans generations.
The plan stems from the long-standing impasse surrounding nuclear energy since the first regular power plants in the 1950s: today, this source accounts for approximately 10% of the world’s electricity, produced by more than 400 plantsHowever, it still depends on temporary solutions for high-level radioactive material, which remains highly radioactive. for hundreds of thousands of years.
The problem that doesn’t fit in swimming pools or promises.
The discussion about nuclear waste It starts with the time scale, not the volume scale.
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Low-activity waste, which amounts to approximately 95% Of the total volume produced, this includes contaminated clothing, tools, cleaning supplies, and medical equipment.
In general, this material remains radioactive for shorter periods and is usually sent to disposal facilities near the surface for a few hundred years.
Intermediate activity waste, approximately 4% Of the total, they mainly consist of used filters and reactor components.
They are more radioactive, but they don’t generate enough heat to require cooling.
Depending on how long they remain radioactive, they may be sent to deeper disposal sites or share facilities with low-level radioactive waste.
The knot is in the last group: the high-activity residues, approximately 1% do nuclear waste worldwide, largely composed of spent fuel.
Even when the rods cease to be efficient for use in reactors, they remain dangerous.
O spent fuel It can remain highly radioactive for up to hundreds of thousands of years, requiring careful handling, shielding, and a long-term strategy.
What exists today: temporary containment and constant surveillance.
The most common routine begins inside the nuclear power plants themselves.
O spent fuel It goes to pools specifically designed for this purpose, where the water acts as a shield against radiation and as a cooling method.
Then, the material can be transferred to what is called dry barrel storage, large, thick steel and concrete containers that isolate the contents from the environment.
The problem is that, even when the initial cooling is complete, the system still depends on… monitoring and maintenance.
Swimming pools need circulation and temperature control to prevent evaporation. Without water, radioactive fuel rods can overheat and melt, releasing radioactive material.
The example cited for this risk is Fukushima in 2011, when an earthquake and tsunami damaged cooling systems, led to catastrophic degradation of the cores, and hydrogen explosions that released radioactive material into the environment.
Therefore, Forsmark’s promise in Sweden is not just to build, but to replace the “short term” with a logic of isolation that attempts to dispense with the human being as the permanent guardian of the nuclear waste.
Why Forsmark became the address of the 100.000-year risk
The Forsmark repository was designed to be a final and permanent repository for spent fuelcapable of maintaining nuclear waste high activity out of reach of the environment for up to 100.000 years.
The location is next to the Nuclear Power Plant of Forsmark and also close to SFR, the Swedish final disposal site for low and medium-level waste, which concentrates logistics in one region.
The choice of the subsoil of Forsmark, the Sweden, is based on three technical arguments presented in the project. First, the geological stability and the very low seismic activity.
Second, a bedrock with few or no known fracture zones.
Third, the age and stability of the rock, described as having formed almost two billion years, remaining virtually stable ever since.
The logic is straightforward: if the rock mass has withstood the test for ages, it may be the last barrier to the nuclear waste.
Underground geometry: a 5 km ramp and a city of tunnels.
Above ground, the facility appears “typical” for a large construction site: storage for excavated earth and rock, buildings for crews and equipment.
What changes is underneath.
From the surface in Forsmark, the SwedenThe project includes a winding ramp of five kilometers descending to a maximum depth of 500 meters.
From this main route, the part that defines the scale originates: a network of tunnels branched that can add up to 66 km, spread across an area of 3 to 4 square kilometers.
Those tunnels are the final destination of nuclear waste the most dangerous in the country, the spent fuel which is currently in temporary storage.
The engineering was designed to reduce direct intervention: each capsule will have its own vertical deposition hole in the tunnel floor, and movement is described as being done remotely, with vehicles developed to minimize human exposure.
6.000 copper capsules and the mathematics of irradiated fuel
The number that shapes the repository of Forsmark é 6.000This is the total number of containers of copper planned, each with approximately 2 tonnes de spent fuel.
The combination of quantity and mass explains why the project is planned as an underground industrial system, not as an isolated “vault”.
Capsules are described as containers for copper on five meters long and one meter of diameter, with an outer coating of copper de five centimeters thick, designed to withstand corrosion and the mechanical forces of subsurface movement.
Within the copperA cast iron insert is then inserted, responsible for maintaining the spent fuel firmly in place.
Logistics begins before the copper.
After being used in a power plant, the spent fuel It is transported by ship to the facility known as Clab, alongside operational nuclear power plants in Oskarshamnwhere all the spent fuel Swedish is stored temporarily.
The estimated length of stay there is 30 the 40 years, the period cited to allow the radiation to gradually degrade before the encapsulation and shipment stage. Forsmark, the Sweden.
KBS-3 in three barriers: copper, bentonite and rock.
The basic method of the repository of Forsmark it’s called KBS-3, a technique developed by SKB for the permanent disposal of high-activity waste.
The central idea is to replicate, in a controlled manner, the conditions in which radioactive materials exist naturally in the Earth’s crust without contact with humans for very long periods: buried deep within stable rock, far from the environment.
The system was described as a sequence of three barriers.
The first is the capsule of copperAfter the insert is mounted, the seal is made using a technique called friction welding.
Next, the weld joint is inspected to identify cracks and weaknesses that could compromise the seal. Once encapsulated, the assembly proceeds to… Forsmark.
The second barrier is a buffer of bentonite clay, presented as a water absorbent and compared to the substance used in cat litter due to its ability to form clumps.
In its technical function, bentonite serves to prevent the flow of water into and out of a container.
When exposed to water, it expands and makes the deposition hole tighter.
The third barrier is the rock itself. Buried 500 meters underground… Forsmark, the Sweden, nuclear waste It lies beneath geologically stable rock and, according to the design, is isolated from the external environment.
As the capsules enter, the tunnel is sealed with concrete and bentonite clay. At the end, the network of tunnels It would be filled and sealed, as if it had never existed.
Timeline, cost and scale: from 2009 to the year 2080
The repository of spent fuel de Forsmark It is attributed to SKB, a company created by the Swedish nuclear industry to manage and dispose of waste.
The project was initially proposed in 2009 and, after more than a decade of research and planning, it was approved in 2024.
Construction began in January 2025, with an estimated cost of just over $1 billion.
The aforementioned work sequence prioritizes above-ground structures before the complete excavation of the underground network.
It is estimated that the repository will be able to store its first containers of copper until the end of the 2030s, according to the first tunnels get ready, while others tunnels They would continue to be excavated even after the operation had begun.
The timeline is admittedly long.
Full system completion is expected to occur. 2080Until then, the total projected excavation is… 2,3 million cubic meters Made of rock and soil, a volume that helps explain why the “end” of the project is not measured by inauguration, but by saturation and sealing.
Where the plan might be delayed: corrosion, legal challenges, and the weight of the improbable.
Even with construction underway, the plan to Forsmark, the SwedenIt is not described as unanimous. A study by the Royal Institute of Technology… Sweden It is cited that the capsules of copperDesigned to resist corrosion, these devices might be more vulnerable than previously thought.
Furthermore, a Swedish NGO has filed a legal challenge requesting more rigorous safety assessments, which could potentially delay the project for several more years.
These frictions highlight the sensitive point of any solution for nuclear wasteIt is not enough for the method to work under normal conditions.
It needs to withstand material uncertainties, gradual changes in the subsoil, and regulatory decisions, without relying on constant human maintenance.
It is precisely this dependence, typical of swimming pools and temporary structures, that the project of Forsmark Try to reduce it to a minimum.
What remains afterward: a place that only “ends” when it disappears.
The final design of the repository is almost paradoxical.
After depositing the 6.000 capsules of copper and seal the tunnelsThe plan calls for the surface facilities to be demolished and the site to be intentionally left unmarked.
The installation would only be truly complete when it ceased to exist as a visible work of art.
To Forsmark, the SwedenThis means turning a billion-dollar construction site into an indistinct point, while the nuclear waste it would remain below, locked by copper, bentonite and rock.
The inevitable comparison: Finland and the same path.
The report puts Forsmark as one of the first final and permanent storage projects for spent fuel.
The only other facility cited as equivalent is Onkalo, in Finland, planned to come online sometime the year following the aforementioned schedule, using the same technology and techniques as the model of Forsmark.
The existence of two similar projects suggests an engineering pattern that can be replicated, provided the geological prerequisite exists.
Nevertheless, the timeline itself and the technical disputes serve as a reminder that, in the real world, the solution for nuclear waste It’s not an event, it’s a process.
Forsmark, the SwedenThis attempts to close a chapter that nuclear energy opened in the 1950s and never truly closed: where to leave the spent fuel when it remains dangerous for periods that transcend any political, industrial, or human cycle.
The bet is that tunnels deep, capsules of copper And rock sealing can achieve what pools and dry barrels cannot promise without supervision.
If the Sweden That’s right, the nuclear waste It will become a buried problem, not a problem managed day after day. If I’m wrong, The error may be slow.invisible and expensive to fix.
Would you entrust your future to a system sealed in Forsmark, the Sweden, for 100.000 years, or do you think so? nuclear waste Does it still require alternatives before being locked away forever?