Finnish SMR innovation awarded in European Commission Nuclear Innovation Prize contest

News, Press release

Passive heat removal solution developed and patented by VTT received the third place in the European Commission Nuclear Innovation Prize contest.

VTT is developing the LDR-50 district heating reactor to produce low-carbon heat for small, medium-size and large district heating networks. Decarbonization of the heating sector is one of the most formidable climate challenges for cities in Northern and Central Europe.

Small modular reactors (SMRs) are actively developed for a wide range of energy solutions around the world.

- VTT’s reactor concept is designed to operate at around 150 °C temperature and low pressure. The operating conditions are modest compared to conventional power reactors, which simplifies the technical solutions. The technology could be deployable to large-scale commercial use during the 2030’s. The innovation prize is a significant recognition for the work carried out by the LDR-50 design team, and a clear sign that the development is on the right track, research professor Jaakko Leppänen from VTT comments.

The awarded passive heat removal solution plays a major role in the safety design of the LDR-50 reactor. Passive systems enable meeting the extremely high safety requirements of nuclear reactors with simplified technology.

The LDR-50 reactor module is comprised of two nested pressure vessels, with their intermediate space partially filled with water. When heat removal though the primary heat exchangers is compromised, water in the intermediate space begins to boil, forming an efficient passive heat transfer route into the reactor pool. The system does not rely on any mechanical moving parts, which could fail and prevent the cooling function. The invention was granted a patent in November 2021.

More information:

Nuclear Innovation Prize: seven applications awarded | European Commission ( 

pienrektorin jäähdytys
Ville Tulkki
Ville Tulkki
Jaakko Leppänen
Jaakko Leppänen
Research Professor
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