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How to Apply IAEA Design Safety Standards to SMRs


Interest in small modular reactors (SMRs) has gained momentum worldwide as an innovative and reliable low-carbon solution to sustainably meet energy demand. SMRs are advanced reactors that generally produce electricity of up to 300 MW(e) per module. The emergence of new SMR designs and the potential for their near term deployment prompted many Member States to assess their regulatory framework readiness to regulate novel SMR designs. The first in a series of publications by the IAEA is now available to support them in this endeavour.

The publication, Applicability of Design Safety Requirements to Small Modular Reactor Technologies Intended for Near Term Deployment, “identifies directions for further development of additional requirements or guidance. Furthermore, it provides a relevant test case and work methodology for similar studies to be conducted in the near future,” said Aurelian Tanase, Technical Specialist at Canadian Nuclear Safety Commission.

The document is the result of discussions and contributions from representatives of regulatory bodies, technical and scientific organizations, operating organizations and SMR designers and is part of the IAEA’s initiative to provide guidance to licensing authorities based on international consensus and best practices. “The views of an international team of experts of various affiliations and backgrounds enabled a balanced, multidisciplinary approach to different issues and from multiple angles,” Tanase added.

Globally, there are about 70 SMR designs and concepts, and the novel approaches of SMRs can pose challenges to the existing regulatory framework. In comparison to existing reactors, proposed SMR designs are generally simpler, and the safety concept for SMRs relies more on passive systems and inherent safety features, such as low power and operating pressure. Read more about the IAEA’s approach to SMR licensing.

Design requirements

The technical document, released in December 2020, is the latest publication supporting the IAEA Safety Standards Series. The document describes the main design characteristics of SMR technologies as compared to large reactors and assesses the applicability of design safety requirements from an engineering perspective. “Taking into account the SMR licensing processes that are being implemented in several countries, the IAEA facilitated discussions about the applicability of the specific safety requirements for the design of nuclear power plants to two SMR technologies intended for near term deployment: light water reactors (LW-SMRs) and high-temperature gas-cooled reactors (HTG-SMRs),” said Palmiro Villalibre, the IAEA Nuclear Safety Officer responsible for the publication. The requirements, sometimes referred to as SSR-2/1 (Rev. 1), centres around land-based, stationary nuclear power plants with water-cooled reactors. “While the publication refers to two specific technologies, it provides insights on how to apply the IAEA design requirements in a technology-neutral, all-inclusive manner,” Villalibre added. 

The applicability of each of the 82 design safety requirements established in SSR-2/1 (Rev. 1) were evaluated to LW- and HTG-SMRs. Though most of the requirements can be applied to SMRs, the publication suggests changes or specific interpretation of eight requirements for LW-SMRs and 30 for HTG-SMRs. For example, given that nuclear power plants incorporating SMRs are being designed to utilize an off-site manufacture for major portions of SMRs, there is a need for the inclusion of manufacturing as one of the provisions associated with the safety requirements for construction. Another example is the requirement addressing the availability of the supplementary control room. For HTG-SMRs, the reliance on such facilities might be of lower importance as these facilities are less dependent on operators’ actions.

“This is one piece of a set of publications that the Agency will issue to assist Member States in application of the Agency safety standards for innovative SMR technologies,” Villalibre said. Additional publications are under development in relation to SMRs, such as those related to safety assessment and emergency preparedness.

Furthermore, the IAEA is managing the collaborative work of a multidisciplinary team of experts for review of the safety standards’ applicability to SMRs to promote the adoption of a consistent approach in all areas of SMR safety. They are developing an overarching safety report, which will provide a roadmap for the application of IAEA safety standards to all types of SMRs. This is expected to be published next year. The roadmap will be based on the review of the applicability of IAEA safety standards to the different stages of the technologies’ lifecycle: siting, design, construction, commissioning, operation, decommissioning, and radioactive waste management.

Read more about the IAEA’s activities related to SMRs.

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