Thermal Hydraulicist

At Amentum, we're not just solving problems; we're engineering the future. Our team is driven by an unyielding commitment to innovation, integrity, and collaboration, tackling some of the most significant challenges in science, security, and sustainability. If you're passionate about making a real impact and want to be part of a community that values ethical excellence, this is the place where your ambition can thrive.

Here, we believe that success comes from continuously pushing boundaries and working together to deliver on our promises. We embrace challenges with confidence and are dedicated to creating a secure and vibrant future for all.

We’ll inspire and empower you to deliver your best work so you can evolve, grow and succeed – today and into tomorrow. We offer an exciting range of opportunities to develop your career within a supportive team who always strive to do the right thing for our people, clients and communities.

Work-life balance and flexibility is a key focus area for us. We’re happy to discuss hybrid, part-time and flexible working hours, patterns and locations to suit you and our business.

About the Opportunity

The Assurance, Technology and Regulation performance unit, is a critical part of the Technology and Consulting business and has been providing critical services to the Nuclear Industry for over 60 years.

Do you want to play a vital role in existing and new defence and civil nuclear programmes in the UK, and want to provide key control and instrumentation support to both defence and civil nuclear sectors? Then this is the opportunity for you.

We are seeking to recruit a Thermal Hydraulicist to join our Nuclear, Science and Engineering (NSE) team in Birchwood, near Warrington.

This role provides a diverse and exciting range of opportunities, undertaking Independent Nuclear Safety and Technical assessment to support the safe operation of all classes of UK submarines across the entire plant life cycle.

From initial concept design through to plant life extension and subsequent decommissioning, this work presents interesting and unique technical challenges and therefore requires a strong commitment to deliver robust safety assurance services to the Ministry of Defence (MoD) in support of the UK’s defence requirements including it’s continuous at sea deterrent.

This role will be of particular interest to candidates with experience in thermal hydraulic modelling who are seeking to broaden their knowledge of the application of codes within design and safety cases.

Key Responsibilities

• Providing independent nuclear safety and technical assessment of documents relating to naval nuclear propulsion plant systems and performance

• presenting advice to relevant safety and technical committees.

• Representing the business at safety and technical meetings with clients, propulsion plant designers and safety case authors.

• Applying personal skills and technical experience to support subject matter experts from other disciplines and projects.

Here's What You'll Need

• Applicants with thermal analysis experience from other industries are also welcomed as comprehensive training will be provided for all successful candidates.

• Degree or Post Graduate qualification in a relevant engineering or scientific discipline.

• Ability to assimilate, analyse and provide judgements on complex technical issues clearly and concisely, based on knowledge and understanding.

• Experience of undertaking thermal hydraulics calculations of Pressurised Water Reactors and/or performance calculations, including faults, severe accident, loss of cooling and decay heat removal conditions.

• Experience of providing assurance activities (formal independent assessment, advice and inspection) in safety or mission critical applications.

• Experience of carrying out Independent Nuclear Safety Assessments.

• Knowledge of Pressurised Water Reactor systems for naval propulsion or civil power generation applications.

• Familiar with modelling codes used within the naval nuclear propulsion or civil power generation programmes.

• Applicants with thermal analysis experience from other industries are also welcomed as comprehensive training will be provided for all successful candidates.

• You will be required to hold or have the ability to achieve full UK security clearance

Our Culture

Our values are built on a strong foundation of safety, integrity, and respect for every individual. People are at the heart of our mission, and we believe in supporting one another through a culture of care and collaboration.

We strive to create a workplace where everyone feels they belong and can thrive. Supporting mental wellbeing and fostering a sense of connection are essential to how we work.

When we embrace different perspectives and work together, we become more innovative, more agile, and more successful.

We partner with VERCIDA, for greater online accessibility please visit to view and access our roles. As a Disability Confident employer, we will interview all disabled applicants who meet the minimum criteria for a vacancy. We welcome applications from candidates who are seeking flexible working and from those who may not meet all the listed requirements for a role.

If you require further support or reasonable adjustments with regards to the recruitment process (for example, you require the application form in a different format), please contact the team.