HTGR High Temperature Gas-Cooled Nuclear Reactor – Prof. Jacek Jagielski

HTGR-POLA Project – Materials Research and Infrastructure

NCBJ Materials Research Laboratory prepared to test the construction materials of the HTGR reactor

The project “Technical Description of a Research High-Temperature Gas-Cooled Nuclear Reactor (HTGR)” was implemented by the National Centre for Nuclear Research (NCBJ) between 2021 and 2024 under Agreement No. 1/HTGR/2021/14. Its total funding amounted to PLN 60 million.

The main outcomes included the basic design of the HTGR-POLA reactor and selected elements of the preliminary safety analysis report. Materials research was an important component of the project, supporting the qualification of structural materials intended for long-term operation under high temperatures, elevated pressure, helium coolant conditions and ionising radiation. Particular attention was devoted to high-temperature metallic alloys, welded joints and nuclear-grade graphite used in HTGR core components.
To support these activities, the research infrastructure of the NCBJ Materials Research Laboratory was significantly expanded. The available facilities enable materials testing at temperatures up to 1,250°C, including experiments conducted in inert-gas and water-vapour atmospheres. The infrastructure includes a high-temperature vacuum furnace, a dilatometer, equipment for measuring thermal diffusivity and conductivity, X-ray diffraction and Raman spectroscopy systems, an LA-ICP-MS system, and equipment for in situ high-temperature mechanical testing. These capabilities are complemented by accredited destructive and non-destructive testing methods, including visual and ultrasonic inspection, metallographic examinations, mechanical testing, hardness and impact testing, and fracture-mechanics assessment. The laboratory can consequently evaluate microstructural degradation, phase transformations, thermal and mechanical properties, irradiation effects and the expected service life of metallic and graphite materials intended for HTGR technology. The project strengthened NCBJ’s capabilities for the qualification and certification of materials for Generation IV nuclear systems and created a foundation for further cooperation with the nuclear industry and international research organisations.