Senior Mechanical Engineer - Machinebouw

Originally named Great British Nuclear, Great British Energy - Nuclear is an arm’s length body of the Department for Energy Security and Net Zero, dedicated to supporting the development and deployment of new nuclear technologies in Great Britain. We play a crucial role in advancing nuclear new build, ensuring the UK’s energy security, and achieving net-zero carbon emissions. Great British Energy - Nuclear focuses on fostering innovation, facilitating investment, and coordinating efforts across the nuclear industry to build a resilient and sustainable energy future. Great British Energy - Nuclear’s first step was to start the technology selection process for Small Modular Reactors (SMRs) in 2023. SMRs can potentially be quicker to deploy and less expensive to build than traditional nuclear power plants because they are smaller, have factory based modular manufacturing and more flexible deployment options. In June 2025, Great British Energy - Nuclear announced that Rolls-Royce SMR had been selected as the preferred bidder to build the UK’s first SMRs, following a technology selection process that began in 2023. Great British Energy - Nuclear is aiming to deliver fast, based on a supportive and collaborative culture which values equality and diversity and creates an inclusive workplace. We draw on deep nuclear expertise – our Executive Committee has over 100 years of nuclear experience at home and abroad. GBN-E will unlock billions of pounds of private and public investment from design to operation, helping to get sites ready for development, and working to grow manufacturing capacity and skills capability. we value diversity and expertise . If you have a disability and would prefer to apply in a different format or would like us to make reasonable adjustments to enable you to apply or attend an interview, please contact us at recruitment@greatbritishnuclear.We have an exciting and challenging opportunity for a Principal Mechanical Engineer position to join our Engineering & Design Services Capability working within the Nuclear Energy Sector. This is an exciting and challenging role where you will perform the Principal Mechanical Engineer role on a range of projects from Concept Studies through to Detailed Design. Working within a multi‑disciplinary team, you will lead the development of mechanical engineering deliverables—including calculations, analyses, reports, and specifications—ensuring high technical quality throughout. You will take ownership of projects and sub‑tasks from a mechanical perspective, and effectively communicate your designs to engineers, designers, construction teams, and key stakeholders across all disciplines. Candidates should be chartered, with strong mechanical design experience in highly regulated industries—ideally nuclear. They must demonstrate solid knowledge of relevant standards, legislation, and engineering principles, supported by commercial awareness and experience in FEED projects. Excellent communication and client‑facing skills are essential, along with the ability to manage multiple projects and build strong stakeholder relationships. The role requires effective leadership within multi‑disciplinary teams, an initiative-taking approach to collaboration, and a commitment to continual professional development. This is a hybrid role with a mix of remote and site/office-based work. You will challenge and deliver value engineering solutions so you will need to be confident and assertive in front of clients. As a Principal Mechanical Engineer, you will lead the mechanical aspects of multi‑discipline projects from feasibility through detailed design, ensuring safe, compliant, and technically sound solutions. You will work across projects, collaborating with clients to deliver innovative, fit‑for‑purpose designs. Your role includes producing and overseeing high‑quality technical documentation, assuring the quality of team outputs, and coordinating effectively with wider engineering teams. You will visit sites as needed, strengthen stakeholder relationships, and confidently present and defend mechanical engineering solutions in client‑facing settings. Leading mechanical engineering aspects of multi-discipline design projects, from feasibility to detailed design stages. Produce and oversee the creation of high-quality design and technical documentation. Provide quality assurance through surveillance, review, and checking of team outputs. Collaborate with multi-disciplinary teams to deliver fit-for-purpose engineering solutions. Ensure safety is an integral part of mechanical engineering design and project delivery. Strong mechanical engineering background, including material selection, tolerancing, geometric tolerancing, surface finishes and welding. Knowledge of crane and lifting equipment design and associated standards (BS2573, LOLER, PUWER, Machinery Regulations). Design experience with mechanical/electromechanical machinery and general fabrications. Competent piping design engineer with working knowledge of ASME 31.3, PER, PSSR and CDM regulations, Safety Case compliance. Ability to produce design packages—including drawings, calculations, method statements, and risk assessments—suitable for manufacture and installation. Experience with space management, equipment layout, and supporting design through construction, commissioning, and plant operations. Familiarity with design guides, piping specifications, standards, and engineering practices. Understanding of nuclear safety case principles and ability to produce design substantiation for safety‑related equipment. nuclear sector experience preferred. Knowledge of mechanical handling equipment and relevant nuclear regulatory requirements. Understanding of Design for Assembly in nuclear environments and knowledge of machining/fabrication manufacturing processes. Capable of producing and checking mechanical engineering calculations and deliverables. Strong report‑writing skills; Specifically for Mechanical Engineering, Rotating Equipment Speciality: Vibration analysis and rotor dynamics (API 617/618/610) Condition monitoring (Bentley Nevada, FFT analysis) Alignment, balancing, and commissioning Performance curves and duty point analysis Gas/steam turbine fundamentals (in nuclear: secondary cycle systems) Commissioning planning and factory acceptance tests (FAT/SAT) Degree in relevant engineering discipline