Phase-based safety review of Micro and small modular reactors from design to decommissioning

The development and deployment of Micro and Small Modular Reactors (MSMRs) is gaining momentum due to their potential for safe, versatile, and environmentally friendly nuclear power generation. This review paper is aimed at examining the safety perspectives of MSMRs, focusing on design principles, regulatory frameworks, construction and commissioning, operational protocols, and decommissioning phases. Ninety-four relevant documents were studied to accomplish the aim of this study, which were identified, evaluated, and included based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The study identified and analyzed 14 safety principles in the design and development phase, 11 regulatory concerns, five major safety considerations during construction and commissioning, three distinct operational safety protocols, and three decommissioning issues for MSMRs. The importance of 14 safety principles and 11 regulatory concerns was explored based on the frequency of studies and their relevance over the timespan until 2024, highlighting the most critical and highly relevant issues. Among the safety principles, inherent and passive safety features, simplified design, and containment safety measures were among the most frequently discussed due to their impact on accident prevention and reactor resilience. Similarly, key regulatory challenges impacting the safety aspects of MSMRs include licensing requirements for unique and varied designs, the lack of reliable assessment methods for passive safety systems, and the absence of a specific regulatory framework, among others.