The international safety assessment of the Finnish SMR design has been finalized.

Finland's nuclear regulator has released a summary report regarding a Joint Early Review conducted alongside regulators from the Czech Republic, Poland, Sweden, and Ukraine to evaluate the safety of Steady Energy's LDR-50 reactor designed for district heating.

Last year, the Finnish Radiation and Nuclear Safety Authority (STUK) performed a preliminary safety assessment of the LDR-50. In June 2025, STUK indicated that the draft concept assessment for Steady Energy's LDR-50 demonstrated that "nuclear and radiation safety, security arrangements, emergency preparations, and nuclear material safeguards could be designed to meet safety requirements." The concept assessment is part of a process outlined in the new Nuclear Energy Act that allows STUK to evaluate whether the power plant generally meets safety standards, distinct from the construction permit process. STUK's assessment was based on this draft concept.

In October 2025, STUK initiated the Joint Early Review of the LDR-50 concept with four nuclear safety authorities: the Czech State Office for Nuclear Safety (SÚJB), Poland's National Atomic Energy Agency (PAA), the Swedish Radiation Safety Authority (SSM), and the State Nuclear Regulatory Inspectorate of Ukraine (SNRIU). The review utilized the early assessment of the plant concept previously completed by STUK.

This review is a voluntary collaboration where each authority independently assessed the plant concept according to its national criteria. It does not form part of the licensing process and does not result in binding decisions or a unified stance on the plant concept. The main goal of the review is to aid in the early design of nuclear facilities and provide non-binding feedback to support the design process.

STUK has published a summary report that consolidates the main observations and insights from the nuclear safety authorities regarding the plant concept. The authorities' conclusions were generally consistent across different countries.

The safety solutions of the LDR-50 nuclear power plant concept highlighted several strengths, including a defence-in-depth approach and the use of passive safety mechanisms. During the early planning phase, the concept was deemed largely appropriate, though not yet sufficient from a licensing viewpoint.

None of the authorities involved in the Joint Early Review found any significant barriers in the areas assessed that would inhibit further development of the concept. However, they stressed that the actual licensing phases will require much more detailed analyses, justifications, and planning, particularly concerning safety analysis, emergency management, and the impacts at the plant level.

Teemu Soukki, the inspector leading the project at STUK, remarked, "It was evident that utilizing a national safety assessment from other countries is complex and demands considerable preparation and clear methodologies. Ensuring that this is feasible needs to be considered during the preparation of the national assessment."

Steady Energy emerged from Finland's VTT Technical Research Centre in 2023. The LDR-50 SMR, with a thermal output of 50 MW, is designed to operate at approximately 150°C. Unlike many SMRs worldwide, it is not intended to generate electricity but solely to produce heat, focusing on district heating, industrial steam production, and desalination projects.

Expressing satisfaction with the Joint Early Review's conclusion, Steady Energy CEO Tommi Nyman stated, "This is a very encouraging result for Steady Energy. We aim to introduce the LDR-50 to international markets, and it is reassuring that the nuclear safety authorities involved in the review found no fundamental obstacles to implementing the reactor concept according to their national safety standards."

The company has already established agreements for 15 reactors in Finland, with STUK currently assessing its reactor design. The goal is to begin constructing the first plant, intended to serve as a clean energy source for a district heating system, by 2029.