Thermal-Hydraulics Engineer

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What will you be doing?

As a Thermal-Hydraulic Modelling Specialist, you will join our advanced engineering team supporting the analysis and performance optimisation of key nuclear energy systems. You’ll contribute to the development and assessment of complex thermal-fluid systems operating in high-integrity environments, helping shape the core of tomorrow’s sustainable energy technologies.

Your main responsibilities will be:

• Lead or support thermal-hydraulic analysis using RELAP5-3D and related tools to model nuclear system performance and transients.
• Develop system-level and component-level models from initial concept to fully validated simulation results, including supporting documentation and justification reports.
• Work within integrated project teams, alongside design engineers and safety analysts, to ensure technically robust, efficient, and compliant outcomes.
• Apply structured problem-solving to complex system behaviours, using parametric studies, sensitivity analysis, and scenario modelling.
• Participate in peer reviews, model validation exercises, and technical governance processes to maintain analytical accuracy and quality.
• Contribute to the system design lifecycle by informing design choices, supporting safety assessments, and enabling performance optimisation.

Who are we looking for?

• We’re looking for proactive engineers with a strong background in thermal-hydraulics who thrive on analytical challenges and want to contribute to cutting-edge energy innovation. If you have experience applying RELAP5-3D or similar system codes in regulated environments—and a passion for system-level understanding—you’ll fit right in. We welcome individuals from nuclear, aerospace, defence, or other safety-critical sectors.
  
  

• We’re hiring at multiple levels—from early-career engineers with strong simulation potential, to experienced analysts ready to lead key modelling scopes.
  
  

You are...

• Passionate about engineering
• result-oriented
• proactive
  
  

Experience, skills and qualifications required:

• Degree in Mechanical, Nuclear, or Energy Engineering (or related discipline)
• Demonstrated experience in RELAP5-3D or similar thermal-hydraulic system codes (e.g. TRACE, CATHARE)
• Solid understanding of fluid dynamics, heat transfer, and system transients
• Experience interpreting P&IDs, system schematics, and technical requirements
• Strong technical documentation and communication skills

Desirable:

• Knowledge of nuclear safety principles, design codes, and licensing requirements
• Experience validating models against test data or benchmark cases
• Familiarity with systems engineering and requirements traceability
• Exposure to digital design integration or multi-physics tools
• Understanding of plant operational parameters and performance limits
  
  

Why join us?

We foster a community of dually talented individuals who are both entrepreneurs and technology specialists. Our teams embody the spirit of innovation and entrepreneurship, enabling us to develop solutions most efficiently.

Our commitment to sustainable growth is unwavering, and we continuously strive for accelerated transformation and continuous improvement. Through ALTEN labs, mentoring programs, internal universities, and more, we are always pushing boundaries and embracing new possibilities.

We offer incredible opportunities to join inspiring projects in the most innovative companies.

We prioritise your career development with personalised support plans tailored to your own aspirations. We're here to empower you and help you reach your full potential.

Join our passionate team and start building tomorrow, today!

In short you get:

• A personalised career path and a rewarding management style
• A chance to work on the most exciting engineering projects and technologies along with Premium Customers
• A huge diversity of engineering projects and industries
• A competitive salary
• Private Medical Insurance
• Pension Scheme
• Cycle-to-work Scheme among many additional benefits
• Social atmosphere, regular gatherings, and team buildings
• Flexible way of working (role dependent)