Senior Principal Mechanical Engineer

Company Description Today, Assystem is among the top three independent nuclear engineering firms worldwide. With over 60 years of experience in highly regulated sectors, the group supports public and industrial stakeholders in the execution of complex and strategic infrastructure projects, subject to high safety and security requirements. Assystem mobilizes 8,000 experts in 13 countries and intervenes across the entire project lifecycle, in engineering, project management and digital solutions.

Job Description ð Join the Fusion and Modular Nuclear Business Unit! ð Take on a pivotal role in shaping the future of clean energy by establishing, leading, and managing the Cooling Water Island engineering team within a groundbreaking Small Modular Reactor (SMR) development program. Drive the development of a high-performing team, overseeing the design, integration, and execution of critical cooling water systems essential to reactor operation.

Play a key role in defining technical strategies, ensuring regulatory compliance, and collaborating across multidisciplinary teams to deliver innovative, high-efficiency engineering solutions that will help revolutionize nuclear power.

Your mission:

Leadership of the Engineering Activities of the Cooling Water Team – Lead and mentor a team of engineers, driving technical excellence, innovation, and collaboration to deliver critical cooling water systems for the Small Modular Reactor (SMR) program.

Development of Safety and Functional Requirements – Define and establish rigorous safety and performance criteria, ensuring compliance with industry regulations and best practices to support safe and reliable reactor operation.

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.

Maintain Equipment Lists and Schedules – Track, update, and manage critical equipment inventories and project schedules to ensure timely delivery and smooth execution of engineering activities.

Management of Risk and Opportunity – Proactively identify potential risks and opportunities, implementing strategies to mitigate challenges and optimize system performance, cost-effectiveness, and overall project success.

Why Join the Community of Switchers?ð Over 55 years in nuclear engineering.ð Ranked among the top 3 largest nuclear engineering companies.ð¼ Attractive social benefits, including an engaging Employee Committee and holiday bonuses.ð Ongoing training with numerous career opportunities.ð 70% of our managers are promoted internally!ð  Hybrid work: 1-2 days remote per week.

QualificationsFEED to Detailed Design Experience – Proven expertise in leading projects from Front-End Engineering Design through to execution.

Multi-Disciplinary Team Leadership – Skilled in managing and coordinating diverse engineering teams.

Steam Cycle Modelling Oversight – Ability to define modelling outcomes and ensure accurate implementation.

Project Budget & Lifecycle Planning – Experienced in budgeting and planning for full design life cycles.

Cooling Water Equipment Expertise – Strong track record in designing and optimizing cooling water systems.

Regulatory & Compliance Knowledge – Well-versed in ONR, Environment Agency, and HSE regulations.

Requirements Capture Experience – Skilled in gathering and…