Role Overview An exceptional opportunity has arisen for a Principal Mechanical Engineer to join a major programme developing next-generation Small Modular Reactor technology. This role offers the chance to work at the forefront of advanced nuclear engineering, contributing to one of the most innovative and high-profile clean-energy initiatives in the world. Engineers who are currently operating at Senior level and are ready to step up into a principal role will also be considered. Key Responsibilities Lead the design and analysis of mechanical systems central to SMR performance, including pressure systems, thermal-mechanical components, and plant-wide mechanical assemblies. Act as Technical Authority for mechanical engineering, providing oversight, verification, and approval of design outputs. Ensure all work aligns with nuclear safety principles, regulatory expectations, and SMR-specific design requirements. Lead the development and substantiation of safety-classified mechanical systems, producing evidence to support safety case submissions. Conduct and review HAZOP, FMEA, reliability assessments, and stress/thermal analyses. Manage project delivery across multidisciplinary teams, ensuring outputs meet quality, cost, and schedule expectations. Engage with clients, regulators, and stakeholders, representing mechanical engineering interests in design reviews and technical disc...