Finland’s Steady Energy and Kuopion Energia consider SMRs for district heating

6 December 2023

Finland’s Steady Energy, a startup company spun out from the VTT Technical Research Centre of Finland earlier this year and municipal energy company Kuopion Energia have signed a letter of intent (LOI) that includes an option for the construction of up to five district heating small modular reactors (SMRs) starting in 2030. This follows a previous LOI signed in October between Steady Energy and Helsinki-based energy company Helen for the construction of up to 10 SMRs for district heating.

Under that agreement, Helen and Steady Energy agreed to launch a planning process with the objective of concluding a pre-investment agreement concerning nuclear heat production within six months.

"We now have an option to build a total of 15 reactors, which would correspond to approximately €1bn ($1.1bn) in turnover," said Steady Energy CEO Tommi Nyman. "The signed letters of intent reflect the strong desire within the energy industry to develop new affordable and low-emission energy technologies for producing district heat."

Finland has a well-developed district heating system, which is mostly produced using fossil fuels, peat and biomass, Steady Energy noted. Utilities are now looking to move to new and innovative low emission alternatives such as SMRs. Steady Energy plans to build the world's first district heating plant based on its LDR-50 SMR by 2030.

The LDR-50 has been in development at VTT since 2020. The 50 MW reactor is designed to operate at around 150 degrees Celsius and below 10 bar (145 psi). Steady Energy says its operating conditions are less demanding than those of traditional reactors, simplifying the technical solutions needed to meet the high safety standards of the nuclear industry.

The project was part of VTT LaunchPad, a science-based spin-off incubator, where VTT researchers and technology are brought together with business leaders and investors to renew industries. VTT LaunchPad supports incubator teams to develop VTT-owned intellectual property rights into fundable spin-off companies.

The LDR-50 reactor module comprises two nested pressure vessels, with their intermediate space partially filled with water. When heat removal through 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 electricity or any mechanical moving parts, which could fail and prevent the cooling function. The innovation was awarded a patent in 2021.

According to Steady Energy, the passive heat removal solution incorporated into the LDR-50 reactor plays a major role in its safety. Passive systems make it possible to meet extremely high safety requirements with simplified technology.

Nyman said the advantages of SMRs include consistent and reliable production, emission-free operation, reasonable cost and minimal use of natural resources. "Additionally, SMRs, as the name suggests, are much smaller in size than traditional nuclear power plants. For example, the newly completed Olkiluoto 3 reactor has a thermal power capacity almost 100 times greater than the 50 MWt unit developed by Steady Energy. SMRs are therefore faster to construct and the facilities can be safely placed underground within the bedrock."

Describing its modular district heating plant, Steady Energy says the physical size of a single LDR-50 unit is comparable to the size of a city bus, lifted to the upright position. During its operating cycle, the reactor produces 600-700 GWh of heat. The peak heating power is 50 MW, but the production can also be scaled down to meet the consumption. In baseload operation the reactor is run at full power during the cold season, and cycle length is around two years. After the operating cycle has been completed, the core is reloaded with fresh fuel. When operating at a lower power level, the fuel is consumed more slowly, and the reloading interval is correspondingly extended.

A district heating plant may consist of one or several independent reactor units, enabling the capacity to be scaled up. In addition to the reactor units, the plant includes auxiliary systems and technical buildings. The overall footprint of the heating plant corresponds to a small or medium-sized industrial site. In addition to an above-ground siting option, the reactor units could also be located in an underground rock cavern. Both options are currently being investigated.

"Our goal is to build the first plants in Finland to demonstrate the feasibility of the technology," Nyman said. "Then we will target the global marketplace. Combating climate change requires a rapid reduction of emissions, and we have one effective solution to offer."

Image: Cutaway of a district heating plant consisting of four LDR-50 reactor units (courtesy of LDR)

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