A unique place to grow your career

At Sellafield Ltd, we are harnessing our expertise; bringing together world-class skills and innovative technology to solve complex nuclear, infrastructure, and engineering challenges. By joining Sellafield Ltd, you join an amazing team of people, from all walks of life, where you can thrive in a connected, considerate culture of innovation, collaboration, and community; and play a significant part in
the UK’s sustainable nuclear future.

The challenges we face are amongst the most complex anywhere in the world. We are using advanced technologies to shape, create and advance the world’s nuclear decommissioning knowledge and capability. That’s why our work is driven by people with a passion for problem-solving and innovation.

About the role

Principal Developers are responsible for designing, developing, and implementing innovative technical software solutions (both on-prem and cloud) that meet our strategic business needs. They serve as Subject Matter Experts for the technical aspects of software products within the ISO portfolio. They’re responsible for the delivery of bespoke applications development and maintenance for projects. They develop and maintain bespoke applications as part of the ISO Development and Configuration capability, delivering solutions in a safe, secure, and professional manner to relevant technical and business best practice and standards in order to support Sellafield Ltd in its technical vision.

The business ambition and appetite for digital transformation has never been so great at Sellafield Ltd as today. Data and Development Managers will play a key role in supporting ISO/ICT, and wider Sellafield Ltd, in developing and utilising digital products by driving strength and depth in their area of expertise: DevOps, business automation, or business intelligence.

The position requires great technical and problem-solving skills to enable leverage of current platforms, to meet business need and align to a product centric way forward for the Enterprise. Challenges include navigating ambiguity, gaining buy-in from stakeholders, and ensuring alignment with wider business objectives. The role may also require advocating for resources, clarifying reporting structures, and refining responsibilities based on evolving demands. Establishing credibility and building relationships will be key to long-term success.

Key responsibilities

• Support the delivery of digital products across ISO/ICT and Sellafield Ltd by developing software components and writing clean, secure, and well-tested code to provide quality solutions.
• Troubleshoot and resolve complex technical issues that arise during development and after deployment.
• Provide technical leadership during all phases of the software development lifecycle (SDLC).
• Ensure that security, stability and capacity are embedded in the development and deployment of services.
• Proactively manage service components in line with key performance indicators (KPIs), supporting service availability and capacity management as well as the identification and resolution of service faults.
• Optimise development processes by analysing existing workflows, identifying improvements, and supporting their implementation.
• Design, review, and support the quality assurance of software solutions to ensure they effectively mitigate security threats.
• Apply modern development techniques and standards to the delivery of all software solutions and encourage adherence to them among other developers.
• Use a variety of prototyping methods, sharing best practice and supporting other developers in their application, while considering the strategic end-to-end design of services.
• Design systems in line with architectural principles, policies and organisational standards. This may also include supporting their implementation and procurement.
• Support systems integration by defining the integration build, coordinating build activities across systems, and participating in testing.
• Support engagement with the Digital & Business Partnering team to understand customer needs and translate them into user stories. This includes identifying appropriate tools and methods to prioritise user stories and clearly articulating the distinction between user needs and desires.

Your Skills and Qualifications

• A degree or equivalent experience in a relevant field, such as Computer Science.
• Strong understanding of agile software development methodologies.
• Excellent problem solving and analytical skills.
• Strong interpersonal skills, demonstrating ability to work in teams and collaborate effectively.
• Strong stakeholder engagement; ability to translate business needs into technical solutions.
• Excellent documentation and knowledge transfer capability.
• Proficiency with Test Strategies, Test Frameworks and Test Automation.
• Proficiency in some or all of the following:
• C#, SQL, PL/SQL, JavaScript, Vue.js, React, HTML, CSS, PowerShell.
• Microsoft Power Platform and PowerApp development.
• Proficiency in K2 and/or ServiceNow.
• Deep Azure expertise across core services (Compute, Storage, Networking, Identity, Security, Monitoring).
• Complex workload migrations into Azure, including operationalisation • DevOps engineering: CI/CD (e.g., Azure DevOps/GitHub), IaC (Terraform, Bicep, ARM), automation (PowerShell, Bash).
• Azure security and governance (Entra ID, Conditional Access, PIM, Defender for Cloud, Azure Policy, RBAC, Key Vault, Private Endpoints, BYOIP/Hub Spoke).
• Experience with cost management (tags, budgets, reservations, rightsizing, workloads on demand).
• Expertise in observability: Azure Monitor, Log Analytics, Application Insights, alerts, workbooks.

Skills Considered Desirable:
• Proven experience as a Full Stack Developer.
• Able to lead and mentor junior developers.
• Knowledge of the Microsoft Power Platform Centre Of Excellence process and governance.
• Experience working in a highly regulated environment.
• Understanding of Sellafield Ltd, including its operations and ICT estate or equivalent.

Why us?

At Sellafield Ltd, we are committed to supporting our employees in fulfilling their potential. With having 100 years of work in front of us, we offer comprehensive training and development opportunities, enabling you to feel inspired in your role. Whatever area you join us in, you’ll find a genuinely exciting and rewarding career.

Making sure our employees feel supported is important to us. Therefore, to help you get the most out of life in and outside of work, we also offer a range of employee benefits:
• You will benefit from an annual bonus of up to 10% – 15%, made up of company and personal performance
• An attractive defined contribution pension scheme – the company will match up to 13.5% for a 7% employee contribution!
• 30 days annual leave + bank holidays. Plus, the ability to purchase an extra 2.5 days per year.
• The ability to carry over 10 days annual leave each financial year
• Paid Sick Leave
• Family Friendly Policies – Visit our Rewards & Benefits page to read more
• Cycle to Work Scheme
• Lifestyle Benefits sasra.co.uk
• Learning & Development Opportunities https://careers.sellafieldsite.co.uk/work-with-us/learning-and-development/
• Reward & Recognition Policies
• Welfare & Employee Assistance Programme
• Free Aviva Health App & Annual Health Check
• MyDiscounts – Employee Savings & Discounts
• MyBenefits – A Charity Giving Scheme
• Many, many more! Click this link to visit our Rewards & Benefits page: https://careers.sellafieldsite.co.uk/work-with-us/rewards-and-benefits/

Sellafield Ltd is a unique place to grow your career, offering a remarkable blend of role variety, job security, personal growth, professional development, and truly significant work. This is your opportunity to tackle some of the biggest challenges in the nuclear, infrastructural and engineering worlds and create a clean and safe environment for generations to come. Explore Sellafield Ltd today.

Additional Information

• The closing date for this vacancy is 14th June 2026.

• In the event of a high number of responses to any advert, Sellafield Ltd reserves the right to close the advert early. Once closed, the advert will be removed from our website. We encourage you to submit your application as soon as possible to avoid disappointment.

• As part of the application process you will be asked to provide evidence of your qualifications. Attaching them at application stage will ensure a smooth process and prevent delays.

A minimum of 3 GCSEs at Grade 4/Grade C or above in English, Maths & Science (or equivalent). Functional Skills Level 2 will also be considered as equivalent to GCSE Grade 4 (Grade C). Other equivalent qualifications may be considered.

• Please regularly check your Spam/Junk folders for news about this vacancy, correspondence could contain invitations to interview and other important updates.

• Sellafield Ltd are recognised as a Disability Confident Employer (Level 3). Disability Confident employers offer an interview to disabled applicants that meet the minimum criteria for a vacancy. Sellafield Ltd define the minimum criteria as the ‘essential skills’ which are listed on the vacancy notice. Whilst completing your application form, you will be able to indicate if you wish to be considered under the disability confident scheme. If you would prefer to discuss this directly with us, please contact the GBS Recruitment team on recruitment@sellafieldcloud.co.uk

• Please be aware that this role is subject to achieving security clearance. This role requires higher level of National Security Vetting where applicants must typically have 5 or 10 years of continuous residency in the UK. Factors such as your nationality, any nationalities you may have previously held, and your place of birth can restrict the level of clearance you’re able to achieve.