Small modular reactors

STUK is preparing for the possibility that there will be desire want to build smaller nuclear power plants with an electricity output of less than 300 megawatts in Finland. STUK is familiarising itself with different types of small nuclear power plants and their specific characteristics, and is participating in international cooperation.

Small modular reactors and nuclear safety

Nuclear power plants with small nuclear reactors must be as safe as large nuclear power plants. The licence holders responsible for the safety of nuclear energy use must comply with Finnish legislation and its supplementary regulation, both in the operation of the installations and in their licensing.


Safety remains a fundamental prerequisite for the use of nuclear energy

Whatever the type and size of reactor, the safety of people and the environment must be ensured. Small nuclear power plants must also be shown to meet the safety objectives set out in the regulation. However, there may be differences in the suitability and application of the more detailed technical requirements between small nuclear power plants and existing large nuclear power plants.

The management of nuclear waste is part of safe use of nuclear energy. Finland is the first country in the world to build a final nuclear waste disposal facility. Similar nuclear waste disposal solutions will also work for water-cooled small reactors. No solutions are yet available for the disposal of spent fuel from other types of reactors.


Safety must always be assessed on a case-by-case basis

Many small nuclear power plants have safety benefits. Low power means lower reactor-specific residual heat and radioactive material, which is beneficial for safety. Low power makes it easier to use passive systems, such as gravity flow of water instead of pumps. This can reduce the dependence on electricity supply and human and equipment activity. However, safety is affected by many factors and must therefore always be assessed on a case-by-case basis.


A small nuclear power plant could potentially be located closer to residential areas than existing power plants

Small nuclear power plants can be located close to residential areas if the safety of the location is justified. For example, in the case of district heating, the plant producing heat must be located relatively close to the population. The safety of the location of the plant must be justified - the plant must not pose a risk to its environment.


The current regulation allows for conventional technology small nuclear power plants

 In Finland, the nuclear regulations are designed for large nuclear power plants and are not fully adapted to small reactors. The licensing and control of a small nuclear power plant based on conventional light water technology would not differ significantly from the licensing and control of existing plants. 

The current overall reform of the nuclear energy legislation will take into account small nuclear power plants. The aim is to allow the licensing of a variety of reactors, provided that safety can be demonstrated. The reform of STUK's nuclear safety code will reduce the level of detail of the requirements and make them more targeted, allowing for different solutions.

International cooperation takes place in several forums

The International Atomic Energy Agency's (IAEA) Nuclear Harmonization and Standardization Initiative (NHSI) aims at common safety assessments and allows other authorities to use their own safety assessments to support their own.

The SMR Regulators Forum is a forum for cooperation between interested IAEA member countries to exchange information and experience on the regulatory control of small nuclear power plants among nuclear safety authorities. It also identifies the specificities of the regulatory framework for small nuclear power plants.

STUK also participates in the OECD's Nuclear Energy Agency (NEA) working group on new technologies and in WENRA's Reactor Harmonisation Working Group. 

STUK also participates in bilateral and multilateral cooperation with nuclear safety authorities in other countries.

Discussions with designers and other actors in the field of small modular reactors

  • Together with the French and Czech nuclear safety authorities, STUK is assessing selected features of the Nuward reactor developed by the French energy company EDF. The project will provide STUK with an opportunity to reflect on how current nuclear energy legislation applies to small nuclear power plants at a concrete level. The lessons learned will be used to develop nuclear energy legislation.
  • In 2022, Fortum launched a study on the conditions for building new nuclear power in Finland and Sweden. Fortum and STUK meet regularly to discuss the study.
  • Rolls-Royce SMR is exploring opportunities for cooperation with Fortum in the field of small nuclear power in Finland and Sweden. As part of this work, Rolls-Royce SMR is in preliminary discussions with STUK on the small reactor it is developing.
  • LUT University has a Memorandum of Understanding with the US company Ultra Safe Nuclear Corporation to build a small gas-cooled high-temperature reactor in Lappeenranta. STUK is holding preliminary discussions with LUT and USNC on the project.  
  • VTT and Steady Energy are developing the LDR-50 district heating reactor. STUK is having preliminary discussions with VTT on the development work. 

Further reading