Senior principal mechanical engineer

Job Description Join the Fusion and Modular Nuclear Business Unit! Assystem has an exciting opportunity for a Senior Principal Mechanical Engineer to join our expanding Fusion and Modular Nuclear (FMN) business unit. As leaders in the design and development of new technologies, you will have the opportunity to work across multiple cutting-edge projects developing technical solutions making net-zero power generation a reality. Your mission: Lead and support the development of designs for the following systems: Personnel Airlocks, Main Equipment Access Hatch, Fuel Transfer Channel, Piping Penetrations, Electrical Penetrations, Specialist Nuclear Doors Conduct DFMEA (Design Failure Mode and Effects Analysis) to identify and mitigate potential failure modes early in the design process. Perform HAZID (Hazard Identification Study) to assess and document risks across the system. Complete and maintain Human Factors Checklists to ensure ergonomics and usability are considered in design decisions. Update and manage the project’s Risk Register to track, evaluate, and mitigate emerging risks. Design Package Production in Line with Requirements – Oversee the creation of comprehensive design packages, ensuring alignment with project specifications, technical standards, and operational needs. Management of Interfaces – Coordinate effectively between engineering teams, suppliers, and stakeholders to ensure seamless integration of cooling water systems with other reactor components. Preparation of Technical Specifications – Develop clear, detailed technical specifications to guide procurement, fabrication, and installation of key cooling water system components. Collaborate with cross-functional teams, including both new and existing FTEs and secondees across engineering and project functions. Why Join the Community of Switchers? Over 55 years in nuclear engineering. Ranked among the top 3 largest nuclear engineering companies. Attractive social benefits, including an engaging Employee Committee and holiday bonuses. Ongoing training with numerous career opportunities. 70% of our managers are promoted internally! Hybrid work: 1-2 days remote per week.