Posiva Initiates Deposition Hole Drilling at Onkalo Repository

Drilling Operations Underway

Posiva has begun drilling the first deposition hole at the Onkalo repository in the Olkiluoto bedrock, more than 400 meters below the surface. The operation commenced after a safety and technical review meeting. The Deposition Hole Boring Machine (DHBM), manufactured by Herrenknecht AG, was delivered to the Onkalo site in June 2022. This machine, weighing 78 tonnes, is over 9 meters long, 3 meters wide, and nearly 4 meters tall. The drilling complex also includes a 7-meter, 22-tonne energy unit and an 18.5-tonne drill processing plant.

Prior to this, Herrenknecht AG's crew conducted test drilling of four holes in late 2022, followed by Posiva's crew drilling an additional four test holes with supplier assistance. The current deposition hole is being drilled vertically into the floor of an excavated final disposal tunnel. Upon completion, it will be 8.4 meters deep and 1.75 meters in diameter. A strict tolerance of 25 millimeters deviation from the vertical centerline is enforced along the entire length of the hole. The first three holes will undergo additional measurements upon completion to ensure compliance. If the deviation exceeds the permitted limit, the hole will be rejected for final disposal.

Repository Development and Future Plans

Kimmo Lehtola, Posiva's Construction Manager for Operations, stated that drilling an 8-meter hole at Onkalo typically takes about ten hours of effective drilling time. The objective is to achieve a production rate of approximately two finished deposition holes per working week once the process is fully integrated into normal operations. The first final disposal tunnel, approximately 330 meters long, is designed to accommodate around 30 drilled deposition holes.

The Onkalo repository, located near the Olkiluoto nuclear power plant, was selected in 2000. Posiva, jointly owned by Fortum and Teollisuuden Voima Oyj (TVO), submitted its construction license application in December 2013, which was granted in November 2015. Construction began a year later. In July 2022, Posiva announced the completion of excavation for the first five disposal tunnels, totaling about 1700 meters. Over the 100-year operational period, an estimated 100 deposition tunnels, with a total length of approximately 35 kilometers, will be excavated. Posiva submitted its operating license application for the encapsulation plant and final disposal facility in December 2021, seeking approval for operations from March 2024 to the end of 2070. The Radiation and Nuclear Safety Authority (STUK) has indicated that safety requirements for the operating license have been met, with a government decision anticipated in the autumn. Posiva's President and CEO, Ilkka Poikolainen, aims for operational readiness by the end of 2026.

Multinational Initiative Launched for Maritime Nuclear Applications

ATLAS Initiative Focuses on Maritime Nuclear Potential

The Atomic Technologies Licensed for Applications at Sea (ATLAS) initiative held its inaugural meeting in the USA, gathering international stakeholders to discuss the future of nuclear energy in maritime applications. A joint statement issued during the event highlighted the potential of advanced small modular reactors (SMRs) as a safe and viable option for the maritime sector. This technology could enable higher-speed commercial shipping with reduced refueling needs and provide versatile energy sources, such as floating nuclear power plants, to supply electricity to coastal or remote communities and industries.

The International Atomic Energy Agency (IAEA) describes ATLAS as the first globally coordinated effort to bridge the nuclear and maritime sectors. The initiative aims to foster collaboration among international nuclear and maritime communities to ensure the safe and secure deployment of these technologies and to enhance safeguards for civil nuclear applications at sea. Advances in reactor design, fuel technology, and maritime engineering suggest that some nuclear maritime designs could be ready for deployment as early as the 2030s.

Broad International Support and Future Workstreams

Initial signatories to the joint statement include Argentina, Bangladesh, Belgium, Brazil, Canada, Denmark, the Dominican Republic, Finland, France, Greece, India, Italy, Japan, Malta, the Netherlands, Norway, Poland, Romania, Saudi Arabia, Singapore, Slovenia, South Korea, Turkey, the UAE, the UK, and the USA. The ATLAS initiative will maintain a technology-neutral approach, acknowledging that designs, business models, and operational concepts for these systems are still in early stages of development.

Following the launch event, six project groups are being established to commence practical work this year. These groups will focus on addressing safety, security, safeguards, and regulatory aspects, while also considering deployment scenarios and other attributes of nuclear-powered shipping and floating nuclear power plants. The IAEA emphasized its role in bringing together regulators, governments, industry, and technology developers to establish the necessary institutional and regulatory frameworks for safe, secure, and safeguarded nuclear technology at sea.

Diverse Applications for Nuclear Maritime Technology

Nuclear maritime technologies are envisioned for a wide range of applications. These include powering large vessels such as container ships, bulk carriers, tankers, cruise ships, icebreakers, and offshore support vessels. Additionally, they could provide reliable electricity, heat, desalination, and emergency power for remote communities, ports, disaster response efforts, and offshore industries. The initiative seeks to transform the promise of offshore nuclear energy and nuclear-powered shipping into commercial reality by addressing practical deployment barriers through collaborative efforts among governments, regulators, and industry.

NuCore Energi Seeks Swedish State Support for New Nuclear Power Project

NuCore Energi, a subsidiary of Fortum, has formally applied for state aid from the Swedish government to support a new nuclear power project in the municipality of Oskarshamn. The application initiates discussions with the government regarding the framework and conditions for promoting the project, which could include both SMRs and large-scale reactors, with electrical output ranging from 1,200 MW to 3,400 MW.

Fortum emphasized that no investment decisions have been made for the project. The final scope will depend on factors such as technology selection, benefits of multi-unit construction, projected electricity demand in Sweden, and risk-sharing arrangements with the state. Fortum intends to gradually reduce its ownership in NuCore Energi, aiming to become a minority shareholder, with expectations for additional private and potentially state investors.

Key conditions for the project's progression include commitments from industrial customers to purchase electricity, long-term political support for nuclear power in Sweden, and NuCore Energi gaining access to the Ävrö land area in Oskarshamn, currently owned by Oskarshamn Kraftgrupp AB, in which Fortum holds a significant stake.

Laurent Leveugle, CEO of NuCore Energi, stated that Sweden's nuclear power policy and risk-sharing model provide a foundation for new nuclear development, which would enhance energy security, stabilize the Nordic electricity system, and support industrial growth in Sweden. Niklas Wykman, Minister of Financial Markets, noted that Fortum's establishment of a project company in Sweden indicates the effectiveness of the country's support model.

The Ministry of Finance confirmed that receiving the application allows for the commencement of the decision-making process for state support. This process involves negotiations between the government and NuCore Energi on the terms and scope of support, as well as ongoing dialogue with the European Commission to ensure compliance with EU state aid regulations.

This application follows a feasibility study launched by Fortum in October 2022 to assess the commercial, technological, and societal aspects of new nuclear power in Finland and Sweden. In March 2025, Fortum announced deepened collaborations with EDF (EPR), Westinghouse-Hyundai (AP1000), and GE-Hitachi (BWRX-300), formalizing these partnerships with Early Works Agreements in June 2025. These agreements cover early project planning, site adaptation, and licensing activities, including pre-licensing discussions with Nordic nuclear safety authorities.

Sweden's government adopted a pro-nuclear stance in October 2022 and unveiled a roadmap in November 2023 aiming for at least two large-scale reactor equivalents by 2035 and up to ten by 2045. A new state aid act, effective August 1, 2025, allows companies to apply for support through state loans, two-way contracts for difference, and risk-sharing mechanisms, subject to European Commission approval.

NuCore Energi's application is among several submitted for state support. The first application was received in December 2025 from Videberg Kraft AB, a Vattenfall AB project company, for approximately 1,500 MWe capacity at Ringhals. In June, Blykalla submitted two applications: one for a 330 MWe plant with six SEALER reactors in Norrsundet, Gävle, and another for up to 440 MWe with eight SEALER reactors at Untra in Tierp. Studsvik also applied in June for up to 1,400 MWe of SMR-based power in southern Sweden, with options in Valdemarsvik and Nyköping. Nordic Baseload Power submitted an application in mid-June for two large-scale reactors totaling about 2,500 MWe at the Barsebäck site.