Reactor System Design Engineer

ALTEN is a global engineering and technology consultancy operating across over 35 countries worldwide. We partner with industry leaders across sectors including Aeronautics, Aerospace, Defence, Naval, Automotive, Energy, Rail, IT and many more to deliver innovative engineering solutions that drive technological advancement & support sustainable transformation.

Our teams of passionate and agile engineers work on cutting-edge projects that shape the future of technology and sustainability. At ALTEN, we empower talented engineers to innovate, solve complex challenges, and deliver impactful solutions that build tomorrow’s world—today.

Join us and start building tomorrow’s world today!

We are seeking a talented Reactor System Design Engineer to join a highly innovative engineering team working on the development of next-generation nuclear technology.

This role will focus on the design and development of Reactor Island systems , including primary and secondary circuit systems, from early concept definition through to detailed design. You'll work within a multidisciplinary environment, collaborating with technical specialists and stakeholders to develop safe, efficient, and compliant system architectures.

This is an excellent opportunity for a Process Engineer or System Design Engineer with 4-8 years' experience looking to work on complex, high-impact engineering projects.

Key Responsibilities:

Lead the design and development of Reactor Island systems, including primary and secondary circuit systems.

Develop system concepts and mature designs through both concept and detailed design phases.

Produce and maintain key design documentation, including: System Design Descriptions (SDDs)

Requirements Specifications

P&IDs

Functional Bills of Materials (FBoMs)

Engineering calculations

Decision logs and optioneering studies

Define system requirements and develop compliant system architectures.

Conduct technical calculations for system and component sizing.

Engage with multidisciplinary stakeholders to ensure requirements are captured and integrated effectively.

Present technical design solutions at formal design reviews and stage-gate assessments.

Ensure designs meet safety, regulatory and operational requirements through the application of Design for X principles.

Required Skills:

4-8 years' experience in process or systems engineering.

Experience applying process system design principles on complex engineering projects.

Ownership of system designs through concept and detailed design phases.

Experience producing: System requirements

System description/design reports

Process flow diagrams

P&IDs

Engineering calculations

Strong technical stakeholder management and cross-functional collaboration skills.

Experience carrying out system optioneering and technical trade-off studies.

Required Qualifications:

A Bachelor’s or Master’s degree in Engineering , or equivalent military experience .

Desirable Skills:

Nuclear industry experience.

Sampling systems design experience.

Experience with reactor, thermal-hydraulic, utility, or process systems.

Knowledge of regulated industries such as nuclear, defence, energy, oil & gas, or chemicals.

Familiarity with systems engineering methodologies and requirements management.

Why join us?

We bring together entrepreneurial, tech-driven people to deliver innovative solutions for leading companies.

At ALTEN, you’ll work on exciting projects, supported by ongoing learning, mentoring, and clear career development tailored to your goals.

Join a passionate team and help build tomorrow, today.

In short you get:

A personalised career path and a rewarding management style

A huge diversity of engineering projects and industries

Private Medical Insurance

Cycle & Tech Scheme

Employee assistance programme

Life insurance & Pension Scheme

Social atmosphere, regular gatherings & team buildings

Flexible way of working (role dependent)

We are proud to support the Armed Forces Covenant & actively encourage applications from members of the Armed Forces community, including veterans, reservists, service leavers, and military spouses/partners. We recognise the value of military skills and experience and are committed to ensuring that no applicant is unfairly disadvantaged during our recruitment and selection processes.

ALTEN is committed to fostering a diverse and inclusive workplace and values the strength that comes from a global mix of backgrounds and perspectives. We welcome applications from all suitably qualified candidates, regardless of background or protected characteristics under the Equality Act 2010. If you require any reasonable adjustments during the recruitment process, please let us know.

This role may require you to have or be willing to go through Security Clearance. As part of the onboarding process candidates will be asked to complete a Baseline Personnel Security Standard; details of the evidence required to apply may be found on the government website Gov.UK. If you are unable to meet this and any associated criteria, then your employment may be delayed, or rejected . Details of this will be discussed with you at interview.