Finnish energy company Helen Ltd is establishing a subsidiary, Helen Ydinvoima Oy, for the development of its nuclear power project. The new company, which will begin operations at the start of February, aims at this stage to investigate the prerequisites for constructing nuclear power in Helsinki and to prepare the project for an investment decision.
“Transferring the nuclear energy programme to its own project development company enables flexible development of the programme as an independent entity,” said Helen CEO Olli Sirkka. “It also creates better conditions for the project’s success by opening up opportunities for various financing and business solutions.”
Helen Ydinvoima Oy continues the work of Helen’s nuclear energy programme, which began in 2024, with the goal of meeting the City of Helsinki’s ambitious emission targets by ending Helen’s combustion-based energy production by 2040 through the use of small modular reactors (SMRs).
Even before that Helen had shown growing interest in Nuclear power. In November 2022, Helen began a joint study with Finnish utility Fortum to explore possible collaboration in new nuclear power, especially SMRs. The companies formed a study group to explore possible synergy benefits.
The following year, in October 2023, Helen signed a letter of intent (LOI) with Steady Energy, valid until 2027, aimed at enabling an investment in a small-scale nuclear power plant for district heating. This included promoting reform of the Finnish Nuclear Energy Act, applying for a site licence and a technological permit, and fixing the contract price of the plant. It also enabled Helen to procure up to ten reactor units from Steady Energy with an output of 50 MWe.
Helen formally established its nuclear energy programme in September 2024 with Sirkka saying that he believed Helsinki would have its own NPP before 2035.
In May 2025, Steady Energy said it planned to build a pilot SMR in central Helsinki at the turbine hall of the Salmisaari B coal power plant, owned by Helen. Steady Energy and Helen signed a lease agreement for the site, valid until 2028. Construction was set to start in late 2025, with a budget of €15-20m ($17-23m) funded by capital investments already raised by Steady Energy.
The pilot facility will comprise a full-scale model of Steady Energy’s LDR-50 reactor module. Steady Energy was spun out of the VTT Technical Research Centre of Finland in 2023. The 50 MW LDR-50 is a simplified pressurised light water reactor specifically designed to operate at around 150°C and below 10 bar (145 psi). The reactor module comprises two nested pressure vessels, with their intermediate space partially filled with water.
In November 2025, Helen and the City of Helsinki began investigating the possibility of building a small NPP in Helsinki and launched an assessment, the first stage of which involves examining three potential sites. These are the Vuosaari and Salmisaari power plant areas and the Norrberget area in western Östersundom.
Currently, Helen is running a competitive bidding process for plant suppliers, exploring business and partnership models, and investigating collaboration opportunities with both industry and other energy companies. The project is assessing the prerequisites for nuclear energy production at previously announced potential plant sites through studies and environmental impact assessments.
Helen Ydinvoima Oy’s Board Chairman is Jarmo Tanhua, who has more than 30 years of experience in the nuclear power sector. He served for 17 years as CEO of Teollisuuden Voima Oyj, during which time Finland’s latest nuclear power plant, Olkiluoto 3, was built in Olkiluoto.
“Jarmo Tanhua is one of the few people in the world who can say they have led the construction of a new nuclear power plant in the 21st century. With his unique experience, we will continue even stronger towards nuclear energy and non-combustion-based energy production,” said Sirkka.
“In Finland, we have good experiences and excellent expertise in nuclear power,” Tanhua noted. “There is a clear need for Helen’s project, and it starts from a new perspective. We want to find out whether it is possible to build and commission the first new small nuclear power plant in Finland. Of course, such a project is of great interest.”
The company’s CEO is nuclear engineer Pekka Tolonen, who has years of experience in the nuclear and energy sectors and has led numerous energy projects. Tolonen moves to his new position from his previous role as Helen’s Director of Electricity Production.
Janne Liuko, who has led Helen’s nuclear energy programme, will continue as the project leader in the new company. The Board will also include Helen’s CFO Timo Rajala, Director of Electricity Production and Optimisation Harri Mattila, and Director of Heating and Cooling Timo Aaltonen.
