UK Office for Nuclear Regulation contributes to IAEA regulatory cooperation toolkit for advanced reactors

The International Atomic Energy Agency (IAEA) recently published the Nuclear Harmonization and Standardization Initiative (NHSI) Regulatory Cooperation Toolkit. The UK Office for Nuclear Regulation (ONR) played a significant role in the development of this toolkit, which is designed to support cooperation among national nuclear regulators in the review of advanced reactor technologies.

The toolkit is one of the key outputs of Phase 2 of the NHSI (2025—2026), developed jointly by multiple regulators participating in the NHSI Regulatory Track and the Small Modular Reactor (SMR) Regulators' Forum. It provides practical guidance, templates, and methodologies to help regulators conduct collaborative reviews, leverage existing regulatory assessment outcomes, and address differences between national regulatory frameworks.

The toolkit comprises two complementary types of resources: one focused on methodologies for resolving regulatory differences, and the other supporting the use of existing regulatory review outcomes. ONR experts contributed to its development drawing on UK experience in developing new regulatory policies, SMR design assessments, international cooperation agreements, and multinational reactor reviews. The IAEA publication also references several UK regulatory practices, including the use of regulatory information in generic design assessments, promoting the internationalisation of assessment work, transparency regarding the regulatory impact of assessed designs, and providing recommendations on regulatory differences through early engagement prior to formal assessments.

The publication reflects years of work under the NHSI Regulatory Track and continues ONR's ongoing collaboration with international partners such as the US Nuclear Regulatory Commission and the Canadian Nuclear Safety Commission.

The release of the toolkit also lays the foundation for the Global Framework for Advanced Reactor Review (GFARR). GFARR aims to establish a harmonised framework for advanced reactor reviews applicable across multiple technology pathways. ONR has already contributed to the development of the first GFARR technical document, which is based on IAEA safety standards and covers defence in depth, safety classification, design basis analysis, and engineered safety systems, to support clearer and more consistent international collaborative reviews in the future.

Diego Fernandez Lisbona, ONR's Head of Advanced Nuclear Technology Regulation and lead for the TerraPower Natrium Generic Design Assessment, stated that the publication of the toolkit represents a significant step forward in international regulatory cooperation, demonstrating that regulators can share experience, build trust, and improve review efficiency without compromising independence or safety standards. He noted that the toolkit is not an end point but a practical foundation for GFARR; as advanced reactors progress globally, such regulatory harmonisation efforts will support the internationalisation of future designs and cross-border review collaboration.