Mechanical Design Engineer

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

As a Nuclear Design Engineer, you’ll be responsible for designing components, assemblies, and systems that meet stringent requirements for safety, cost, availability, and longevity. From early concept through to in-service support, you’ll ensure every design is resilient, efficient, and built to perform under real-world conditions.

You’ll work across nuclear plant systems and supporting equipment—including tooling, assembly/disassembly systems, and maintenance solutions—contributing to every stage from design to deployment and beyond.

What You’ll Be Doing

• Develop innovative, reliable design solutions aligned with system and sub‑system requirements
• Manage projects from concept through to verification, delivery, and in‑service support
• Collaborate with stakeholders across engineering, manufacturing, and service teams
• Lead design verification through testing and analysis
• Maintain safety justifications and resolve in‑service issues
• Interpret test data and validate designs against analytical models
• Drive continuous improvement in tools, processes, and methods
• Support supplier assessments and qualification activities
• Ensure compliance with technical standards, safety requirements, and company values
• Deliver projects on time, within budget, and to quality standards
• Identify and manage technical, cost, and schedule risks
• Lead investigations, technical packages, and problem resolution
• Provide expert guidance within your engineering discipline
• Support production, integration, maintenance, and decommissioning activities
• Define and execute verification, qualification, and safety strategies

Qualifications

• Degree (Bachelor’s, Master’s, or PhD) in Engineering or equivalent experience
• Proven experience in design engineering across the product lifecycle
• Strong analytical, problem‑solving, and innovative thinking skills
• Experience with safety justification, product integrity, and verification methods
• Background in R&D, testing, and analytical modelling
• Membership (or working towards) of a relevant professional body

Benefits

• Work on nationally significant, technically complex projects
• Strong career development and progression opportunities
• 25 days annual leave (buy and sell leave scheme)
• Opportunity to make a real impact in energy, defence and infrastructure

Security Clearance

This role requires the successful candidate to hold a minimum of a Security Check (SC) clearance without any caveats to that clearance.

Due to the nature of work, this role will be delivering and protecting certain assets; the successful candidate must be a UK national or, in MoD approved cases, a Dual National from a non‑ITAR country.

We are committed to equal treatment of candidates and promote, as well as foster all forms of diversity within our company. We believe that bringing together people with different backgrounds and perspectives is essential for creating innovative and impactful solutions. Skills, talent, and our people’s ability to dare are the only things that matter! Bring your unique contributions and help us shape the future.

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