Finland’s nuclear safety regulator has found no fundamental barriers to Steady Energy’s LDR-50 small modular reactor design, following an international safety review.
The Finnish Radiation and Nuclear Safety Authority (STUK) has published a summary report of the Joint Early Review (JER), a voluntary assessment of the LDR-50 concept carried out by five national nuclear safety authorities.
STUK led the review alongside the Swedish Radiation Safety Authority (SSM), Poland’s National Atomic Energy Agency (PAA), the Czech State Office for Nuclear Safety (SÚJB), and Ukraine’s State Nuclear Regulatory Inspectorate (SNRIU). Each authority independently assessed the reactor concept against its own national regulatory framework.
The review was not part of a formal licensing process and does not amount to regulatory approval or a licensing decision in any of the participating countries.
The assessment drew on LDR-50 design documentation available in early 2025, together with STUK’s early-stage concept assessment completed in the summer of 2025. Steady Energy said the design has continued to develop significantly since then.
The review found that current documentation was not yet detailed enough to support a formal licensing process – an expected outcome for a concept at this stage of development. However, all five regulators reached broadly consistent conclusions, with none identifying fundamental nuclear safety issues that would prevent the concept progressing to further development.
STUK’s summary report highlighted the LDR-50’s extensive use of passive safety features and its defence-in-depth design philosophy as strengths of the concept. It added that future licensing processes will require more detailed engineering, safety analyses and technical documentation, in line with standard progression from concept design to licensing.
Tommi Nyman, chief executive of Steady Energy, said: “This is a highly encouraging outcome for Steady Energy. Our ambition is to bring the LDR-50 to international markets, and it is a very positive signal that the nuclear safety authorities participating in the review did not identify any fundamental obstacles to implementing the reactor concept in accordance with their national safety requirements.”
Alice Neffe, Steady Energy’s country manager for Poland, said the review carried particular significance for the country’s district heating sector: “Our partners in Poland’s district heating sector are professionals in heat, not necessarily nuclear technology. That’s why this review matters: preliminary as it is, five independent regulators, including PAA, see no fundamental obstacle to a technology that can replace fossil fuels while delivering the same stable heat supply.”
Anton Steen, Steady Energy’s country manager for Sweden, said: “This is very good news and highlights that nuclear heat is a realistic solution for district heating in Sweden during the 2030s.”
The JER is one of the first international initiatives in which multiple nuclear safety authorities have used an early-stage safety assessment performed by another regulator as a reference point when evaluating an advanced small modular reactor concept. STUK said the experience gained would support future international regulatory cooperation on new nuclear technologies.
Steady Energy said it will continue advancing the LDR-50 towards detailed design and future licensing processes in Finland and international markets.
Image credit: Natali _ Mis/Shutterstock
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