Principal Mechanical Engineer
Confirmed on the employer's own hiring board on Sep 24, 2026. First seen by Alion on Jul 6, 2026. Assystem scores B on the Alion truth index.
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 mobilizes 8,000 experts in 13 countries and intervenes across the entire project lifecycle, in engineering, project management and digital solutions.
We are looking for an experienced Mechanical Engineer to support the technical capability of the Client Design Authority (DA). This role will be suited to engineers with experience in Mechanical Design, although candidates experienced in Mechanical Installation or Maintenance are also welcomed.
What You'll Do
- Produce and review high-quality infrastructure design packages and technical specifications.
- Define reliability, performance, and operational requirements for infrastructure systems.
- Assess maintenance and work control procedures to support safe and effective operations.
- Evaluate infrastructure design, material condition, ageing mechanisms, and asset suitability to support continued facility operation.
- Promote a strong safety, security, and compliance culture across all activities.
- Act as an intelligent customer, ensuring safety-related contracts and technical deliverables meet contractual and regulatory requirements.
What We're Looking For
- Broad mechanical engineering experience, with knowledge of systems such as pumps, cranes, HVAC, pressure systems, or diesel generators.
- Experience in the nuclear sector or another highly regulated/high-hazard industry is desirable but not essential.
- Ability to develop practical, innovative, and cost-effective engineering solutions for plant and infrastructure modifications.
- Good understanding of British and international engineering design standards.
- Strong analytical skills with the ability to make informed, evidence-based decisions using a range of technical data.
- Excellent written and verbal communication skills, with the ability to engage effectively with stakeholders.
- Well organised, with the ability to manage priorities and deliver work to agreed timescales.
Qualifications & Experience
Essential
- HNC (or equivalent qualification/experience) in a relevant engineering discipline.
- Strong understanding of the design intent for mechanical infrastructure within the nuclear sector or a similar highly regulated industry.
⭐ Desirable
- Incorporated Engineer (IEng) status, or equivalent experience.
- Degree (or equivalent qualification/experience) in Mechanical Engineering or a related discipline.
Why join the community of Switchers?:
The Group is currently ranked Third in the world for nuclear engineering.
A dynamic career management policy to enable our employees to progress through our five business lines: operations, project, technical, sales and support functions
Provide opportunities to work on exciting, global projects
Access to an employee assistance programme with free mindfulness, health, wellbeing resources and a confidential support line available 24/7 via phone or text
Discount vouchers for days out and restaurants, eye test and glasses vouchers, cycle to work scheme, free flu jabs
At Assystem, we celebrate diversity and creativity. We believe in harnessing unique perspectives to shape innovative solutions. Your skills and daring spirit are what truly matter. Join us and help shape the future!
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.
Umbrella contractor or permanent staff
Requires sole UK national with SC clearance
Mainly remote working with 1-2 days per month at our client site in Helensburgh.
NOTICE TO CANDIDATES ON RECRUITMENT FRAUD - We are committed to safeguarding candidates from fraudulent activity associated with our recruitment process. Please note that we will never offer specialist CV writing services, request payment or ask for sensitive personal information during the recruitment process.
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.