The Euratom NPHyCo project: Conceptualization, technical work plan and current status

This manuscript provides an overview of the goals, technical content, and close-to-final status of the Euratom NPHyCo project. NPHyCo stands for N uclear P owered Hy drogen Co generation, and its ultimate goal is the design and preparation of a large-scale (MW-range) hydrogen cogeneration facility coupled to a nuclear power plant (NPP), which can become operational in a short-term horizon. The project analyses the existing economic, technical, safety and regulatory considerations for NPP owners to produce nuclear hydrogen through several cases of study applied to selected NPP sites and European markets. The manuscript summarizes the main outcomes as of December 2024 regarding the integration scenarios of a hydrogen production plant (HPP) into a NPP site, based on the coupling configuration and sharing of balance-of-plant components between facilities. Given the interest and degree of cooperation of the Ukrainian state operator Energoatom, most of the technical calculations are based on the specifications of Rivne and Khmelnytskyi NPPs, both powered with water-water energy reactor (VVER) technology. The project has delineated a HPP configuration with an overall capacity of 45 MW. The safety assessment relies on deterministic and probabilistic methodologies, which are applied through numerical simulation tools. The results are mostly based on example scenarios. However, they allow to derive general conclusions. Deterministic calculations are applied to a hydrogen plant either in a container or building solution, to determine the optimal configuration and required safety measures upon an intended release of hydrogen and subsequent ignition, leading to a fire or explosion. The hazards of the worst-case scenario in the HPP towards safety-related NPP structures are evaluated based on onsite and offsite HPP integration at Rivne NPP, with the corresponding structural fragility criterion. The techno-economic study addresses the hydrogen value chain, encompassing low-temperature and high-temperature electrolysis technologies, up to storage and transportation. The study evaluates if existing systems and resources at the NPP are sufficient and suitable to supply the HPP, and thereby lead to reduced capital expenses (CAPEX) and operational expenses (OPEX). A summary of techno-economic analysis is summarized in this paper. Several sensitivity analyses have served to obtain the configuration to minimize the levelized cost of hydrogen (LCOH) and advance operational strategies to determine the best dynamic configuration for the hybrid system operation. A final business plan for hydrogen production by means of already existing NPPs, has been also developed. For the licensing of the HPP in the vicinity of the NPP, the degree of integration and distance between facilities are the most critical factors. The licensing impact is investigated for three different levels of plant integration.