In the Euratom funded GEMINI + Project, the design basis for a standard HTGR system meant at delivering steam to industrial sites has been defined. The new Euratom GEMINI 4.0 project optimises the design of the GEMINI+ reactor (core design, flow at the core outlet and related thermal fatigue of components, use of burnable poisons, etc.) to make its safety demonstration more robust. In parallel, guidelines for licensing such a high temperature reactor are under preparation. On the other hand, a roadmap for developing the manufacturing in Europe of the TRISO fuel required by this reactor is defined, as well as a fuel back-end route compatible with European regulations. But beyond optimisation of the design of the nuclear system, the main objective of GEMINI 4.0 is to show that, at the same time as cogeneration of process heat and electricity for industrial customers studied in GEMINI +, this system can supply these customers the hydrogen they need in addition for full decarbonisation of many of their processes. The project shows that, for satisfying the net-zero objectives of the European Union, there must be, in the next decades, a huge development of hydrogen production without CO2 emission. Using high temperature nuclear technologies deployable in the short-term is the most appropriate solution to face in an economically realistic way such intensive growth of consumption of the highpressure hydrogen generally required for industrial applications. As the technology of the GEMINI + system is mature enough for a short term deployment, the project shows indeed that poly-generation (that is simultaneous supply of hydrogen, process heat and electricity) is feasible with such a system: flow sheets for coupling it with high temperature and pressure water splitting processes, like the steam electrolysis or the iodine sulphur thermochemical process, are defined and the economic competitiveness of such coupling is assessed. The project also analyses the specific risks related to the use of a nuclear plant for poly-generation and identifies possible mitigation methods for these risks. Finally, GEMINI 4.0 makes special efforts for communication towards the general public, the industrial potential users and political stakeholders. Communication is critical for the deployment of nuclear poly-generation, which is indeed a new application of nuclear energy and will require new scattered nuclear sites, close to industrial activities. Therefore, both the users and the public must get familiarised with the benefits they will get from this new extension of the use of nuclear to accept and desire it.

HITTNER Dominique;  PASQUET Michel;  MALESA Janusz;  FUETTERER Michael;  TOUGAIT Olivier;  BAUDRAND Olivier; 

2025-10-20

International Atomic Energy Agency

JRC144263

https://inis.iaea.org/records/6szjr-mga90,    https://publications.jrc.ec.europa.eu/repository/handle/JRC144263,