forumNordic

Unveiling Nordic Innovations

Innovative Small Nuclear Heat Reactor Can Reduce Fossil Fuel Emissions

Steady Energy Ltd was established in June 2023 as a spin-out company from Technical Research Centre of Finland (VTT), one of Europe’s leading research institutions owned by the Finnish state.

Matti Pentti, COO, notes, “Our company’s objective is to produce Low-temperature District heating Reactors (LDR) which are small modular nuclear reactors operating at conditions suitable for heat production without using any steam turbines. The reactor relies on well-established tried and tested low-pressurised water technology, combined with a passive safety design.”

The core personnel at Steady Energy bring together extensive experience from nuclear industry, with some 60 VTT professionals who continue to work on nuclear energy projects, plus some 20 other energy professionals who also have many decades of experience from Finnish nuclear industry, their regulators, research bodies, and various other energy sectors.

Summary of Reactor Project

  1. Adjustable low-heat power 50 MW max per reactor
  2. Delivered temperature 160 °C max
  3. Working pressure 8 bar max
  4. Refueling every 2-3 years
  5. Located in deep underground reactor cavern as strong as a civil defence shelter
  6. Contained in physically separated water circuits at lowest pressure inside the reactor, therefore preventing any possible leak retained inside plant
  7. A new governmental-backed study, expected to be released shortly, approves that the reactor plant may be located safely inside cities, in special fortified underground caverns 
  8. They are based on proven and safe existing technology
  9. Detailed technology dedicated to Steady Energy
  10. LDR’s nuclear energy has as low CO2 emissions as offshore wind.


This modular LDR is the simplest and most economical use of nuclear energy that heats water at temperatures below 160 °C, and that can cut up to 10% of global COemissions by the gradual replacing of fossil fuel heating plants. 

Although there are some similarities with the systems and functions of big nuclear power plants, these LDRs can reduce production and operating costs to acceptable levels even though the regulatory licensing and implementation requirements are almost the same as for big plants.

The total production of district heating is some 513 TWh within the EU27, where 250 TWh of the required heat is produced by fossil fuels. Steady Energy aims to replace these fossil fuel plants utilizing existing transmission infrastructure with their small low-temperature modular reactors that are located and operate deep inside in underground caverns.

Design Innovations of Steady Energy’s LDR

The advantage of low operating temperature is that the reactor operates at a low pressure of around 8 bars, which is close to an espresso machine or a bottle of champagne. This simplifies reactor design. The required wall thickness for pressure vessels is just a few centimetres, which allows the components to be manufactured using conventional technology. Safety design is simplified because accident scenarios do not involve high pressure situations as in big nuclear reactors.

They have developed some innovative cooling solutions that are an essential part of the safety features of their reactor. The safety design of the reactor relies on passive systems, enabling the very high level of safety required for nuclear reactors to be achieved with simple double-wall pressure vessel technology.

In terms of licensing and implementation by STUK, the nuclear regulator, almost the same requirements must be met as for large production units. This means that a commercial product requires a planning and construction time period of 6-10 years for the first reactors to be in operation in the 2030s.

Mr. Pentti states that Steady Energy has Letter of Intent signed with municipal energy companies, HELEN Oy (in Helsinki) and Kuopion Energia Oy (in Kuopio, another Finnish city) with options for more than 10 reactors to be delivered in Finland. Plans are also ongoing for export deliveries to various markets in Europe – the graph above illustrates that there is no lack of opportunities!

The company’s product, as planned, has no chimney, no emissions, no stack of coal, no biomass or tanks, no trucks, no trains, or ships, and can supply a steady flow of heat at a relatively steady price, in a secure manner.

At this early stage, the financing has been led by VTT, Yes VC, Lifeline Ventures with others, including the founders.

© 2024 forumNordic. All rights reserved. Reproduction or distribution of this material is prohibited without prior written permission. For permissions: contact (at) forumnordic.com