Assystem
Principal Mechanical Engineer
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Principal Mechanical Engineer
Assystem – Senior Mechanical 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 executing complex and strategic infrastructure projects with high safety and security requirements.
Assystem employs 8,000 experts across 13 countries, covering the full project lifecycle—engineering, project management, and digital solutions.
About the Role
Are you an experienced Mechanical Engineer seeking to lead ambitious, technically demanding projects in a high-stakes industry? We’re looking for a passionate, collaborative professional eager to tackle complex engineering challenges, drive teams, and deliver innovative solutions for our clients.
Are you excited by engineering excellence and thriving in fast-paced, multidisciplinary environments? We’d love to hear from you!
Key Responsibilities
Your mission will include:
- Leading and inspiring engineering teams to develop cutting-edge technical solutions.
- Collaborating closely with Project Managers, Lead Engineers, clients, and cross-disciplinary teams to ensure timelines, budget, and safety standards are met.
- Communicating technical progress to stakeholders and aligning projects with business goals.
- Mentoring and supervising engineers, including nurturing junior talent.
- Effectively delegating tasks while fostering collaboration and teamwork.
- Proactively identifying and managing project risks, seizing opportunities wherever possible.
- Overseeing delivery of engineering work packages and assuring technical quality at every stage.
- Authoring and reviewing technical documentation, design reports, and engineering files.
- Managing your workload while supporting the team to meet deadlines and standards.
- Continuously developing your expertise and knowledge for both personal and project growth.
- Engaging with clients and subject matter experts across nuclear safety, operations, and safety domains.
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Qualifications and Experience
Essential:
🎓 A 2:1 BEng in Mechanical Engineering (or equivalent qualification). 🏅 Chextered Engineer status (or commitment to Chartership preferred). 🪓 Industry experience in regulated sectors such as nuclear, chemical, or energy. 📁 Technical documentation and compliance experience—including PED, PUWER, and LOLER.
Advantageous:
🎓 A Master’s degree in Mechanical Engineering. 🏢 Senior leadership or direct experience in complex infrastructure or safety-critical projects. 💻 Proficiency in 3D CAD tools (e.g., AutoCAD, Revit, AutoCAD Plant 3D, PDMS, or MicroStation) (training available if needed). 🔄 Experience in Risk-Led/MBSE (Model-Based Systems Engineering) methodologies and lifecycle design. 📊 FEA expertise (e.g., ANSYS, CAESAR II, or FlowMaster). 📜 Strong grasp of nuclear safety standards and collaboration with Nuclear Safety Engineers. 🔧 In-depth knowledge of mechanical piping systems, supports, vessel design, and dynamic analysis.
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Desirable:
Compliance with BS EN 61508/61511 Functional Safety standards. NEC3/NEC4 contract management skills, including risk identification and dispute resolution. Deep technical and operational understanding of piping and mechanical systems (valves, pumps, specific codes such as ANSI/ASME). Experience working in nuclear power generation, legacy decommissioning, or high-net-zero energy projects. Supplier management and the ability to specify and monitor third-party deliveries.
Behavioral Competencies:
- Advocacy: Articulating technical complexity clearly across multidisciplinary and non-engineering teams.
- Safety Leadership: Upholding safety standards consistently in project execution.
- Resilience: Managing multiple concurrent projects and competing deadlines with clarity and focus.
Important Considerations
Security & Export Control: This role is subject to industry-standard precautionary measures. Candidates will need to satisfy:
- Baseline Personnel Security Standard (BPSS).
- Further vetting requirements (e.g., DV/SC, depending on remit).
Eligibility varies by nationality and residency. Assystem is committed to equality, diversity, and inclusion. We recognise that diverse backgrounds amplify innovation.
We will never:
- Ask for payment at any stage.
- Request personal financial data (e.g., bank details).
- Provide specialised CV writing services as part of the hiring process.
Bring your expertise, dedication, and ambition to help shape Assystem’s future.
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Jessica, London
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