Towards commercial heat production

Development of the LDR-50 district heating reactor was started at VTT Technical Research Centre of Finland in February 2020. Substantial additional funding was allocated to the project in January 2023, enabling the participation of some 30–40 experts in the technical development.

In June 2023, a VTT spin-off company called Steady Energy was established for the purpose of commercializing the LDR technology. VTT will continue the basic design in the frame of a project agreement made with the company. Steady Energy will supplement the work by an experimental program, which includes, for example, the construction of a large-scale electrically heated thermal hydraulics test facility.

After the experimental programme has been completed, Steady Energy will become the supplier of LDR technology, with VTT as its technical support organization. The first nuclear heating plant is scheduled to be commissioned by the end of the decade, after which the technology is finalized for commercial serial production.

Frequently asked questions about reactor development

Contact information

More information about the project:

  • Project manager: Senior Scientist Tapani Ryynänen
  • Technical development: Research Professor Jaakko Leppänen
  • Contact by email:

More information about Steady Energy:

Collaboration with external parties

During the development phase, VTT and Steady Energy will collaborate with various industrial parties and end users of heat. In the initial phase, the collaboration is mainly carried out through subcontracts with companies specialized in nuclear engineering, construction technology and pressure components. The list of partner organizations is updated along with the progress.

EcoSMR-Hub community

In 2019–2022, VTT coordinated the EcoSMR ecosystem project funded by Business Finland, with the goal of promoting Finnish expertise in small modular reactor technology and creating collaboration networks between industrial parties. Nuclear district heating was one of the central topics. Studies related to SMR technology development and business opportunities will be continued within the EcoSMR-Hub community, to be established during 2023.

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