Nuclear Harmonization and Standardization Initiative

The Nuclear Harmonization and Standardization Initiative (NHSI), launched in 2022, is aimed at facilitating the effective global deployment of safe and secure advanced nuclear reactors, including SMRs.

In October 2024, participants gathered for the third NHSI Plenary, marking significant progress under both the Industry Track and the Regulatory Track and charting the course for Phase II. The Industry Track’s four Topical Groups focused on: harmonization of high-level user requirements; common approaches on codes and standards; experimental testing and validation through the newly established NEXSHARE collaborative data sharing network; and accelerating infrastructure implementation for small modular reactors. Five white papers were published, focusing on the work of the groups and covering serially manufactured products, non-nuclear codes and standards, and long-lead items.

The Regulatory Track’s three Working Groups produced (i) a framework for regulatory cooperation in design reviews, including a framework for sharing information among regulatory bodies, (ii) a multinational pre-licensing joint review process through which regulators can jointly evaluate specific technical areas of a proposed reactor design, (iii) a process for leveraging reviews already completed by regulatory bodies in other Member States and (iv)a collaborative review process that allows regulators to work together in parallel during ongoing national regulatory reviews. This work is captured in three technical documents, to be published in 2025.

During 2024, the Initiative laid the groundwork for Phase II (2025–end 2026), which will focus on the implementation of Phase I outcomes and cover new areas, including nuclear security considerations.