Thermal coupling between a small modular nuclear reactor and a high-temperature steam electrolysis process: energy performance mapping of key design options

• 16 layouts coupling a Small Modular Reactor to High-Temperature Electrolysis compared. • A 13% H 2 production gain obtained by the main layout vs the uncoupled thermal layout. • Results on the main configuration deviate by 3% from a freely available heat layout. • Results on the main configuration outperform the heat-pump solution by more than 4 %. • The solutions with two-ways thermal coupling more efficient than the one-way layout. This article presents the main results of a three-year R&D program on the coupling of a Small Modular Reactor (SMR) nuclear unit to a hydrogen production process using High-Temperature Steam Electrolysis (HTSE). Different coupling architectures are investigated and their energetic evaluation is performed in comparison with a reference configuration. The separate effects that are considered are comprehensive and include: thermal coupling (with or without, unidirectional or bidirectional − modulo internal heat recovery effort in the HTSE process itself), direct or indirect steam supply, location of the Rankine cycle extraction point, pressurization of the HTSE (with or without mechanical energy recovery through gas expansion) and oxygen content (impact of the swept gas). Remarkably, the simulation results obtained on the reference configuration show a gain of over 13% in hydrogen production compared with the solution involving no thermal coupling between the SMR and the HTSE process (when HTSE heat is provided through electrical heaters), with a deviation as low as 3 % from an idealized configuration with freely available heat. It even outperforms the heat-pump solution by more than 4 %. These key energetic results were supplemented by other technical criteria, such as those relating to safety and technological maturity.