Principal Mechanical Engineer – Nuclear & Fusion Systems Lead

Assystem UK Ltd; Bagstone; Hybrid; GBP 90,000 - 140,000; Full time

Benefits offered by this job

Hybrid work

Job summary

Assystem UK Ltd is seeking a Principal Engineer to lead Front End Engineering for Small Modular Reactors, Advanced Modular Reactors, and Fusion projects. You will head an engineering design team, integrating new systems into the wider plant and driving safety-focused design decisions.

You will mentor junior staff, perform optioneering, and deliver compelling ALARP and BAT arguments while ensuring compliance with ASME, European and UK standards. UK security clearance eligibility is preferred.

Qualifications

• Experience in highly regulated industries like nuclear, thermal power generation or oil and gas.
• Proven ability to perform optioneering and studies to evaluate viable options.
• Track record of leading small teams and mentoring staff.
• Excellent communication with internal and external stakeholders.
• Familiarity with ASME, European and UK codes and Product Safety Legislation.

Responsibilities

• Deliver Front End Engineering activities for Small Modular Reactors, Advanced Modular Reactors and Fusion projects.
• Lead engineering design teams and integrate developed systems into broader plant infrastructure.
• Chair design reviews and drive ALARP/BAT arguments to ensure safety and efficiency.
• Mentor junior staff and ensure compliance with statutory H&S and Quality Management systems.

Skills

Nuclear experience

Thermal power

Oil & gas

Optioneering

ALARP/BAT arguments

Team leadership

Mentoring

Stakeholder communication

ASME/UK codes

Product Safety Legislation

Systems engineering

Security clearance (UK)

Job description

Assystem UK Ltd is seeking a Principal Engineer to lead Front End Engineering for Small Modular Reactors, Advanced Modular Reactors, and Fusion projects. You will head an engineering design team, integrating new systems into the wider plant and driving safety-focused design decisions.

You will mentor junior staff, perform optioneering, and deliver compelling ALARP and BAT arguments while ensuring compliance with ASME, European and UK standards. UK security clearance eligibility is preferred.