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Home Senior Mechanical Engineer

Our Vacancy

Senior Mechanical Engineer

  • Defence
  • Permanent /
  • Derby
  • United Kingdom
  • 18/10/25
  • On site

Assystem is an international company with one mission: accelerate the energy transition around the world.


Every day, our 7,500 switchers located in 12 countries (Europe, Middle East, Pacific Asia & Africa) connect their six thousand billion neurons to tackle the task of the century: switching to low-carbon energy.


We are a collective committed to the actors who are making the energy switch. Sharing our knowledge, expertise and values allows us to innovate and think differently about the energy transition.


Drawing on more than 55 years’ experience in highly regulated sectors subject to strict security and safety requirements, we provide our customers with engineering and project management services, as well as digital services and solutions to optimise the performance of complex infrastructure projects throughout their life cycle. The Group is currently ranked third in the world for nuclear engineering.


To ensure a viable, efficient, and reliable energy future for all.


Job Description

Your future team:

Are you ready to ignite your career in engineering with thrilling challenges and ground breaking projects within Nuclear and Defence? Assystem Energy & Infrastructure are expanding its team in Derby and are looking for enthusiastic Engineers to join our innovative team

 Your Missions:

📸 To have experience in reviewing concessions of engineered parts and ensuring they meet with Engineering Standards, design intent, and update engineering substantiation documentation to ensure the component satisfies fit, form, and function.

🧩 To have good understanding of modelling and drawing practices and be able to demonstrate appropriate CAD competencies for integration and modification activities.

⚙️ Be influential and experienced across all stages of the design lifecycle (e.g., creating analysis models using ANSYS or ABAQUS, producing tolerance stack calculations, creating, developing, and maintaining the master model and associated definition – model-based design (MBD) and 2D).

🏭 Have experience in Design for Manufacture activities and a deep understanding of manufacturing buy-off processes, right through to supporting parts in service.

🔩 To have strong manufacturing process understanding in machining, castings, forgings, rotary equipment, and an appreciation of welding techniques.

🧾 Managing and maintaining data integrity is vital to this role, so attention to detail is essential.

📐 Created and maintained per company procedures, definition/drawing standards, models/definitions at component and assembly levels, examining interfacing components, and identifying problems based on nominal or adverse tolerance effects during manufacturing processes.

🤝 Collaborate and communicate with design, manufacturing, and the wider integrated project team, offering support at gated reviews.

🌱 Support junior team members and work effectively in a team-oriented environment.

My profile

🔧 Experience as a Senior or Principal Mechanical Engineering in the nuclear, aerospace, or regulated sector

 🧾 Experience in ASME Y14.5, GD&T or equivalent standard.

 ⚠ Understanding of safety legislation and obligations

 📚 High degree of knowledge around Design for Manufacture & inspection methods.

🖥 Familiarity with 3D CAD systems (Siemens NX or similar) for model and drawing creation

📂 Familiarity with PLM systems (Teamcentre or similar)

🎓 Professional qualification in an engineering related field

 Please be aware that many roles at Assystem are subject to both security and export control restrictions.

  • These restrictions mean that factors such as your nationality, any nationalities you may have previously held, and your place of birth can restrict the roles you are eligible to perform within the organisation.
  • All applicants must as a minimum achieve Baseline Personnel Security Standard. Many roles also require higher levels of National Security Vetting where applicants must typically have 5 to 10 years of continuous residency in the UK depending on the vetting level required for the role, to allow for meaningful security vetting checks.

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.

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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