The HTGR-POLA high-temperature gas-cooled nuclear reactor, developed by scientists from the National Centre for Nuclear Research, may play a significant role in the decarbonisation of energy-intensive industries requiring access to steam and heat at very high temperatures. The completed basic design and advanced safety analyses of the research and demonstration reactor have just been presented in the prestigious journal of the American Nuclear Society, Nuclear Technology, confirming the maturity and international potential of Polish Generation IV reactor technology.

In order to carry out an effective energy transformation in Poland, it is necessary to combine renewable sources and nuclear energy. However, this applies not only to electricity production, but also to the decarbonisation of industry. For many industries, this is a complex issue, mainly due to the demand for high-temperature heat. One solution could be high-temperature gas-cooled reactors (HTGR), which enable the production of steam at temperatures above 500°C.

Although this technology has been known for over 50 years, its potential has never been fully utilised. It is only with the ongoing climate change and the need to move away from fossil fuels that interest in this type of reactor has been renewed. HTGRs are now among the most promising of the so-called Generation IV nuclear reactors. Despite Poland's limited experience in developing nuclear technologies, which have so far been based on small research reactors, the current situation provides an opportunity to join the world's leading manufacturers of nuclear reactor technologies. The project that offers this opportunity is the HTGR-POLA reactor developed at the National Centre for Nuclear Research (POLski Atomowy).

NCBJ has been involved in projects related to the implementation of HTGR reactor technology for almost 15 years. Projects such as HTR-PL, GEMINI+ and GoHTR have not only allowed us to gain experience in designing this type of reactor, but also provided an opportunity to conduct market analyses and create legal, organisational and technical instruments for their market implementation. All these activities have enabled the next step, which is to design the HTGR-POLA high-temperature reactor from the ground up. The cooperation with the Japan Atomic Energy Agency (JAEA), established in 2019, has played a key role in this process. The HTTR (High Temperature Engineering Test Reactor), which has been operating in Japan since 1998, became an important source of knowledge that NCBJ specialists gained thanks to the commitment of both parties, acquiring a 50% share in the intellectual property of the basic design. 

The HTGR-POLA reactor design incorporates the latest technological solutions, compared to the HTTR, which was developed over 30 years ago. Although both are research reactors and serve as technology demonstrators, there are fundamental differences between them, which have influenced the solutions used in the HTGR-POLA. These differences are presented in the latest scientific paper by the project leaders from both sides: Prof. Mariusz Dąbrowski and dr Hirofumi Ohashi in the American Nuclear Society's journal Nuclear Technology. It shows that the first significant difference is the heat exchanger – in the Japanese reactor, the heat produced in the reactor is released into the atmosphere, although in the near future it will be used to test the possibilities of zero-emission hydrogen production. The HTGR-POLA project will feature a steam generator with a temperature of over 550°C, which will be used for industrial applications. There are also significant differences in the design of the fuel assemblies. Instead of fuel channels integrated with the cooling system, the Polish design separates the channels containing the fuel from the channels cooling the reactor core through which gaseous helium flows. The aim to increase safety through the use of passive systems has also resulted in differences in the design of the core itself. In the case of HTGR-POLA, the core has a significantly larger height-to-diameter ratio (approximately 2.17, compared to 1.26 for HTTR). This solution will allow the core design to be scaled up from a 30 MWt research reactor to a 180 MWt commercial reactor, while maintaining safety requirements. This will also be possible by reducing the active area of the core and placing an additional layer of neutron reflector in it. As a result, in the higher-power commercial version, the diameter of the core will remain the same, and only its height will increase by adding additional layers of fuel blocks. This solution will also facilitate the transport and manufacture of reactor components. 

The Polish reactor is designed to continuously generate electricity and process heat. Therefore, a very important part of the project is the Energy Conversion Installation, or the so-called conventional island. It includes a steam generator, an electricity-generating turbine, as well as a reboiler, which will be responsible for supplying high-temperature heat to the industrial facility. The reactor will also be able to supply district heating to local consumers. In the HTGR-POLA project, the entire conventional island was developed by scientists from the National Centre for Nuclear Research (NCBJ) and engineers from the Polish company Energoprojekt Katowice.

Although the main application of HTGR reactors is the production of high-temperature heat, work is underway to adapt them for other purposes as well. These include, for example, the production of hydrogen by steam electrolysis, methane-steam reaction, or methane pyrolysis. Such work is currently being carried out on the Japanese HTTR reactor. Although the basic design of the HTGR-POLA reactor does not currently envisage connecting it to a hydrogen production facility, the strong interest of companies in the hydrogen industry in this technology is prompting consideration of this application during the development of the technical and detailed design. Similar interest in the potential of HTGR reactors can be seen on the part of the petrochemical industry and synthetic fuel production.

According to some analyses, the use of zero-emission high-temperature reactors to replace existing installations in energy-intensive industries could reduce capital expenditure on replacing ageing equipment by up to 35% and lower electricity costs by 9 to 28%. This prospect makes HTGR technology very attractive, and the HTGR-POLA reactor and its future commercial variant a solution for the decarbonisation of industry not only in Poland, but also in Europe and worldwide.

The full study is available in the publication: Dąbrowski, M. P., & Ohashi, H. (2026). Polish-Japanese Collaborative Design of the Research-Demo High-Temperature Gas-Cooled Reactor HTGR-POLA. Nuclear Technology, 1–10. https://doi.org/10.1080/00295450.2025.2562640.