Senior Principal Mechanical Engineer

Assystem is a global leader committed to accelerating the energy transition. With 7,750 employees across 12 countries, we tackle the monumental task of switching to low-carbon energy. Our 55+ years of experience in highly regulated sectors ensure we deliver top-notch engineering, project management, and digital solutions.

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 responsibilities include:

• Leading and supporting the development of designs for systems such as Personnel Airlocks, Main Equipment Access Hatch, Fuel Transfer Channel, Piping Penetrations, Electrical Penetrations, and Specialist Nuclear Doors.
• Conducting DFMEA (Design Failure Mode and Effects Analysis) to identify and mitigate potential failure modes early in the design process.
• Performing HAZID (Hazard Identification Study) to assess and document risks across the system.
• Completing and maintaining Human Factors Checklists to ensure ergonomics and usability are considered in design decisions.
• Updating and managing the project’s Risk Register to track, evaluate, and mitigate emerging risks.
• Overseeing the creation of comprehensive design packages, ensuring alignment with project specifications, technical standards, and operational needs.
• Coordinating interfaces between engineering teams, suppliers, and stakeholders for seamless integration of cooling water systems with other reactor components.
• Preparing detailed technical specifications to guide procurement, fabrication, and installation of key cooling water system components.
• Collaborating with cross-functional teams, including both new and existing FTEs and secondees across engineering and project functions.

Why join us?

• 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.

Qualifications:

• Leadership experience managing multidisciplinary engineering teams.
• Experience in Steam Cycle Modelling and defining modelling outcomes.
• Proficiency in project budgeting and lifecycle planning.
• Strong background in designing and optimizing cooling water systems.
• Knowledge of regulatory and compliance standards (ONR, Environment Agency, HSE).
• Experience in requirements capture and systems engineering principles.
• Management of subcontractors.
• Chartered Engineer (CEng) qualification.
• Eligibility for SC security clearance.

Additional skills and attributes:

• Excellent communication skills, both written and oral.
• Strong leadership capabilities.
• Focus on delivering quality within time and budget constraints.
• Integrity and ability to inspire it in others.
• Understanding of interdisciplinary challenges beyond own discipline.
• Ability to work independently with initiative and self-motivation.
• Comfort working in a multi-party, multi-national environment.
• Willingness to travel within the UK for work as needed.

Applicants must meet residency criteria for UK security clearance if not already cleared to SC level. We promote diversity and equal opportunity, believing that varied backgrounds and perspectives foster innovation and impactful solutions. Your unique contributions will help us shape the future.