Senior Mechanical Engineer

About the role

Assystem is seeking a Senior Mechanical Engineer to join its Fusion and Modular Nuclear Business Unit. Reporting to the Turbine Island Lead, you will drive the design development of the Turbine Island for nuclear power projects, collaborating with multidisciplinary teams and the supply chain.

Key responsibilities

• Validate supplier deliverables against project requirements.
• Create and review Process Flow Diagrams, P&ID, layout drawings, sizing calculations, datasheets and specifications.
• Lead optioneering studies, decision records, design descriptions and requirement specifications.
• Apply systems engineering principles to develop functional and design requirements.
• Integrate Turbine Island design with the overall power plant architecture.
• Provide technical support for Turbine Island interfaces and stakeholder activities.
• Participate in design reviews, HAZID/HAZOP studies and safety licensing processes.
• Ensure compliance with health & safety policies, project quality standards and the Quality Management System.

Required profile

• Experience in nuclear, thermal power, oil & gas or other highly regulated sectors.
• Proven background in steam turbines, condensers, feedwater heaters, pumps and piping systems from FEED to detailed design and EPC delivery.
• Strong procurement expertise, including development of specifications and supplier collaboration.
• Excellent communication skills with internal and external stakeholders.
• Ability to manage critical interfaces and project milestones.

Required skills

• Process Flow Diagram (PFD) creation
• Piping & Instrumentation Diagram (P&ID) development
• Layout drawing and sizing calculation
• Technical datasheet and specification authoring
• Optioneering and decision‑record analysis
• Systems engineering (functional and design requirements)
• HAZID/HAZOP study participation
• Nuclear safety licensing and environmental permitting knowledge
• Steam turbine, condenser, feedwater heater and pump design

What we offer

• Hybrid work model (1‑2 remote days per week)
• Attractive social benefits and holiday bonuses
• Continuous training and clear career progression
• Internal promotion culture – 70% of managers promoted from within