Finland’s Posiva Oy says the final disposal of used nuclear fuel will be tested without used fuel in the coming months. Posiva, which is responsible for the final disposal of used nuclear fuel, is jointly owned by Finnish nuclear utilities Fortum and Teollisuuden Voima Oyj. The construction licence for Posiva’s repository at Eurajoki, near the Olkiluoto NPP, was granted in 2015 and work began the following year. The site was selected in 2000.
In the trial run phase, the equipment and systems of the final disposal facility will be used for the first time in accordance with jointly designed processes. The experiments are designed to ensure that safe final disposal is ensured before the operation begins.
The fuel cools down about 40 years before the final disposal. At Posiva Oy’s final disposal facility, the fuel is encapsulated in cast iron capsules surrounded by corrosion-preventing copper shell. The capsules are placed in the Onkalo facility in final disposal holes drilled to a depth of about 430 metres, surrounded by bentonite clay.
During the trials, the operation of the final disposal facility will be tested in its entirety, but without the used fuel. Four capsules are placed in eight-metre-deep holes in a final disposal tunnel about 70 metres long. The final disposal tunnel is then filled with bentonite clay and closed with a concrete plug. The trials will also test the recovery of damaged capsules back to the ground surface.
The final disposal of used nuclear fuel in Finland will be the world’s first project of this kind. The plant has many unique devices and systems that have been created as a result of decades of research and are now being used together for the first time, Posiva noted. the test run, which is also being called a co-operation test, will take several months.
Posiva’s subsidiary, Posiva Solutions, with its unique expertise, has offered the world’s nuclear waste organisations the opportunity to participate and learn how safe final disposal is implemented in practice. “The cooperation test is significant wayfinder in managing the last missing link in the sustainable use of nuclear energy, namely the return of used fuel back to the rock, said Posiva.
Posiva has been preparing for the disposal of used nuclear fuel for more than 40 years. Its encapsulation plant is located above ground, and the fuel repository of underground disposal facility is located in the bedrock at a depth of approximately 400-430 metres. Posiva has applied for an operating licence to the Ministry of Economic Affairs & Employment and expects to dispose of their used fuel in the facility between 2024 and 2070.
The government will make the final decision on Posiva’s application, after the Radiation and Nuclear Safety Authority (STUK – Säteilyturvakeskus) has given its approval. STUK began its review in May 2022 and the ministry had requested STUK’s opinion by the end of 2023. Earlier this year, STUK asked for the deadline to be extended until the end of 2024 noting that the project was progressing without major problems, but at a slightly slower pace than was previously anticipated.
