VTT spin-out to build SMRs for district heating

A new spin-out from Finland’s VTT Technical Research Centre is designing a new type of small modular reactor (SMR) to decarbonise domestic heating with nuclear energy.

The nuclear startup – named Steady Energy - recently raised €2m to advance its technology. In development at VTT since 2020, the LDR-50 SMR operates at around 150 degrees Celsius and below 10 bar (145psi), delivering a heat output of 50MW. Steady Energy claims these conditions are less demanding than traditional reactors, making it inherently safer and easier to meet nuclear certification.

“The pressure required by the LDR-50 reactor is comparable to the pressure that of a household espresso machine,” said Steady Energy CEO, Tommi Nyman. “It operates at a lower pressure than a district heating network. This ensures that in case of a malfunction which leads to a leak, the leak is contained within the heating plant, without endangering people or the environment.”

Decarbonising domestic heating is one of the biggest challenges of the energy transition, with around 50 per cent of all energy consumed by EU households going towards keeping homes warm. District heat consumption in Europe is approximately 500TWh, 300TWh of which is produced by fossil fuels.

“To preserve our planet and ensure generations to come have a healthy planet, all combustion-based heating must come to an end,” Nyman continued. “Alongside renewable energy, nuclear energy provides a steady source of energy and heat that meets the needs of modern society and helps us in our fight against climate change.”

Steady Energy CEO Tommi Nyman - VTT/Steady Energy

“75 per cent of district heating systems in the EU are currently powered by fossil fuel. The situation is even worse in China. Nuclear energy is already a major source of low-carbon electricity, and small modular reactors represent a pathway to expand the use of the technology to other energy sectors in addition to heating.​”

The LDR-50 reactor module is made of two nested pressure vessels, with their intermediate space partially filled with water. If heat removal through the primary heat exchangers is compromised, water in the intermediate space begins to boil, creating an efficient passive heat transfer route into the reactor pool. The system does not rely on electricity or any mechanical moving parts, which could fail and prevent the cooling function. VTT says the innovation was awarded a patent in 2021.  

As well as being safer than other reactors, VTT and Steady Energy say the LDR-50 will also be cheaper, making it accessible to countries where nuclear power has traditionally been considered out of reach.

“On top of being safer than traditional reactors, SMRs are more affordable,” said Nyman. “We’re setting up a demonstration plant for district heating purposes ideally in Finland, but our long-term plan is to have several plants operating around the world, producing carbon-neutral heat to homes, offices and for various industrial applications.”

Steady Energy is currently working on a 1:1 scale mock-up of the LDR-50 that is powered by electric heat. The company plans to build the first LDR-50 reactor-based heating plant by 2030.