Principal Layout Integration 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 mobilises 8,000 experts in 13 countries and intervenes across the entire project lifecycle, in engineering, project management and digital solutions.

Reporting to the Layout Engineering Manager, the Principal Layout Integration Engineer will provide technical leadership across Fusion and Modular Nuclear programmes.

The Principal Layout Integration Engineer will act as a recognised subject‑matter expert for plant layout integration, piping layout, building integration, modularisation and multidisciplinary coordination. The role will support project delivery, capability growth, business development and the development of engineering best practice.

Whilst providing technical leadership and strategic direction, the Principal Layout Integration Engineer will remain actively involved in project delivery, supporting development of complex layouts, technical studies and the resolution of challenging engineering issues.

• Lead plant layout development from concept through detailed design for complex facilities and plant areas.
• Act as technical lead for major buildings, systems or programme‑level integration activities.
• Lead development of equipment, piping, cable tray, access and maintenance arrangements.
• Lead piping routing studies and layout optimisation activities.
• Provide technical leadership across multiple projects and programmes.
• Lead requirements‑driven layout development and multidisciplinary integration activities.
• Define layout integration methodologies, standards and engineering approaches.
• Lead major optioneering, constructability, modularisation and plant integration studies.
• Lead complex multidisciplinary reviews and technical workshops.
• Provide technical assurance and review of layout deliverables.
• Lead resolution of complex layout, routing, requirements and integration challenges.
• Ensure layout solutions satisfy operational, safety, constructability and lifecycle requirements.
• Support bids, proposals and client engagement activities.
• Develop layout standards, procedures and best practice guidance.
• Mentor engineers and support capability development.
• Support recruitment, succession planning and capability growth.
• Author and review technical reports, engineering strategies and client‑facing documentation.

Join Assystem and become a key player in delivering critical nuclear projects that shape the future of energy. Embrace this opportunity to excel in a dynamic environment where your expertise and leadership will drive global innovation.

• Pension scheme (8% company contribution / 4% personal contribution)
• 25 days paid annual leave + bank holidays + option to buy or sell days
• Professional fees reimbursed
• Flexible working
• Employee referral scheme

• Degree qualified in Mechanical Engineering or related discipline, or equivalent industrial experience.
• Extensive experience in plant layout, piping layout, plant integration and multidisciplinary engineering delivery.
• Experience leading complex engineering studies and technical decision‑making.
• Strong understanding of systems engineering principles, requirements management and interface management.
• Strong understanding of constructability, maintainability, modularisation and lifecycle considerations.
• Experience leading multidisciplinary teams, workshops and design reviews.
• Experience supporting major design reviews, technical governance activities and engineering assurance processes.
• Experience using E3D, PDMS, Plant 3D, Siemens NX, Revit, Inventor and Navisworks, or equivalent platforms.
• Excellent report writing, presentation and stakeholder management skills.
• Proven ability to influence senior stakeholders, clients and project teams.
• Ability to define engineering strategy whilst remaining engaged in technical delivery.
• SC Clearance or capable…