Finland’s Onkalo wins operating licence, but disposal must wait

Nearly fourteen years after Posiva applied for permission to build Finland’s permanent spent-fuel repository, the project has reached another threshold: permission to operate it. The company says the Finnish government granted Onkalo an operating licence on October 22, 2026. That advances a long effort to give nuclear fuel a permanent destination—but it does not mean disposal has begun. ^{18 2}

Before spent fuel can be permanently placed underground, Posiva must complete commissioning tests and inspections, and Finland’s Radiation and Nuclear Safety Authority, STUK, must verify and approve that work. No opening date has been set, Al Jazeera reported on October 23, citing the operator. The next milestone is not another announcement of intent; it is regulatory acceptance that the facility and the people running it are ready. ¹

Onkalo is intended to become the world’s first permanent underground repository for spent fuel from commercial nuclear power plants. That distinction is narrower—and more meaningful—than calling it the first nuclear-waste disposal site. Other countries already have final-disposal facilities for low- and intermediate-level radioactive waste. Spent reactor fuel is the particular challenge Finland is working to resolve. ^{6 29 41}

The facility is at Olkiluoto in Eurajoki, western Finland. Its above-ground encapsulation plant connects to an underground disposal facility; STUK’s September 2021 description places the intended destination of canisters transferred down the canister-hoist shaft at 420 metres. That is a documented repository level, not a measurement of every tunnel in the complex. ^{6 29}

Onkalo began as an underground research facility, where investigators studied whether Olkiluoto’s bedrock was suitable for final disposal. Research, construction and testing have all served the same eventual purpose. But digging into the rock, assembling disposal equipment and rehearsing its use are different achievements from permanently disposing of radioactive spent fuel. ³⁰

Posiva’s owners are Teollisuuden Voima, known as TVO, and Fortum Power and Heat. Their disposal programme covers spent fuel from the Olkiluoto and Loviisa nuclear power plants and is described as serving Finland’s five reactors. Loviisa is part of that intended programme, even though Fortum holds separate permissions for its power station and associated waste-management facilities. The precise reactor-by-reactor conditions of the final Onkalo licence have not been independently verified for this report. ^{17 6 1 12}

The stated design capacity is 6,500 tonnes of uranium. The unit matters: it measures the uranium associated with the fuel, not the combined weight of fuel, canisters and other packaging. It is also a design figure, not a binding maximum independently established from the final operating licence. ¹

Commissioning is more than checking whether individual machines switch on. Posiva’s integrated trial was designed to test equipment, systems, processes and the organisation together, including the personnel expected to operate them. A repository must function as a coordinated operation, not simply a collection of completed components. ³⁵

There has already been substantial preparatory work. On May 3, 2024, Posiva reported that underground ventilation and piping had been completed and commissioned to the extent required for the trial run. That was readiness for a defined test phase—not a declaration that all commissioning was finished. ³⁶

Test operation began on August 30, 2024, using non-radioactive dummy fuel elements. A December 16 update confirmed that the integrated trial had begun at the end of August and that its tests used no spent nuclear fuel. Those accounts establish that rehearsal began; they do not establish completion and final acceptance of the entire trial programme. ^{34 35}

A later approval was similarly specific. On November 25, 2025, Posiva reported that STUK had approved the construction plan for an extruded copper tube forming part of the disposal canister’s copper shell. That was a component-plan approval, not approval of the entire completed canister or permission to start repository operations. Nor should a manufacturing approval be mistaken for demonstrated long-term containment. ³⁹

The October licence announcement is a more consequential step, but its legal particulars still require care. The grant is documented in Posiva’s announcement; the final government decision instrument was not independently obtained for this report. Its effective period, binding quantities and detailed conditions therefore cannot be certified here, and earlier application documents cannot substitute for the final decision. ^{2 14}

The financial figures need comparable discipline. Al Jazeera put the site’s estimated cost at $1.16 billion. Separately, French reporting on October 23 described an approximate €1 billion construction cost. These concern the same project and should not be added together; an exact conversion between the estimates has not been established. Neither is a verified total for the facility’s entire operating life. ^{1 23}

A Posiva-associated disposal-facility cost record in the International Nuclear Information System illustrates the broader obligations: underground rock characterisation, above- and below-ground investment, operations, decommissioning the encapsulation plant and closing the repository. Building Onkalo is only one part of paying for permanent disposal. A dated operator baseline connecting all those obligations to the headline construction estimate remains unverified. ²¹

What remains unresolved is the timetable. There is no verified test-by-test completion schedule, confirmed date for STUK’s final pre-start acceptance or opening date. Posiva, led by chief executive Ilkka Poikolainen, still has to finish the commissioning work and secure the regulator’s approval. October’s licence moves Onkalo closer to its purpose. It does not establish that any radioactive spent fuel has yet been permanently disposed of there. ¹