Jaakko Leppänen

Dr. Jaakko Leppänen is the Research Professor for reactor safety at VTT Technical Research Centre of Finland. He also holds the title of Adjunct Professor at Aalto University. Dr. Leppänen’s professional background is in reactor physics, especially neutron and radiation transport calculations. He is the original author of the Serpent Monte Carlo code, which is used more than 250 universities, research organizations and companies around the world. Since, 2020 Dr. Leppänen has been leading the technical design of VTT’s LDR-50 district heating reactor.

Title of presentation: Nuclear energy for district heating

The energy sector is one of the major consumers of fossil fuels, and therefore also a major contributor to carbon emissions. In many contexts, energy is used as a synonym for electricity, but in reality, most of the world’s primary energy is consumed as transportation fuels and heat. Investing into low-carbon electricity production consequently provides only a partial solution to the climate crisis. Decarbonizing the industrial and heating sectors is necessary for meeting the climate goals, and this requires more drastic changes in the ways energy is produced and consumed.

In 2020, VTT Technical Research Centre of Finland started the development of a small low-temperature nuclear reactor for the purpose of district heating. The LDR-50 reactor is specifically designed to supply heat for small, medium-sized and large district heating networks in Finland, but the potential market also covers other European countries with cold winter climate. The motivation for the development is to provide a low-carbon replacement for fossil heating fuels, taking into consideration independence from the electricity market, and requirements for security of supply.

The LDR-50 features a combination of conventional light water reactor technology and passive safety design. The unit size is 50 megawatts, and the heating plant may consist of one or multiple independent reactor units. The reactor operates at around 150 degrees temperature, without any turbine cycle. In 2023, the project received significant new funding, which enabled moving the development into a new phase. The first demonstration plant is to be commissioned by the end of the decade, followed by commercialization of the technology in the 2030’s.

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  • Title of presentation: Nuclear energy for district heating