The Senior Nuclear Systems Engineer supports the development of a next‑generation nuclear power plant as part of a multidisciplinary engineering team responsible for Nuclear Island (NI) systems‑level design. This role is intended for experienced engineers who can act as a technical authority for assigned NI systems, independently leading system‑level design, integration, and licensing activities while mentoring junior engineers in a highly regulated environment. Supporting the SMR‑300, this position works closely with engineering, manufacturing, and licensing teams as part of a U.S. Government cost‑shared development program, developing system requirements, specifications, analyses, and design documentation to support safe, compliant, and executable plant designs.Location: Almondsburry, UK or Madrid, SpainPrimary ResponsibilitiesLead multi‑disciplinary system engineering and integration activities across major SMR‑300 plant systems, ensuring technical consistency and alignment across engineering disciplinesDevelop and manage system requirements, interface definitions, and component specifications to support detailed design, analysis, and licensing activitiesServe as a technical mentor to early‑career and mid‑level systems engineers, providing design guidance and reviewing calculations, specifications, and technical deliverablesPerform and oversee engineering analyses and calculations, particularly in areas related to thermal‑fluids and overall plant system performanceConduct and support technical trade studies and design evaluations that inform high‑impact decisions affecting plant architecture, safety, and performanceCoordinate closely with licensing, safety, and regulatory teams to ensure system designs support safety case development and meet applicable codes and regulatory expectationsCollaborate with internal engineering teams, suppliers, and manufacturing partners to ensure system designs are technically sound, manufacturable, and executableSupport technical reviews, design documentation development,



and internal design approval processes in alignment with program milestones and quality standardsServe as a technical lead for assigned Nuclear Island systems, owning system integration, requirements, and cross‑discipline alignment.Execute assigned system‑level engineering scope for the SMR‑300 development program, delivering work with a high standard of quality, safety, and regulatory rigorRequirementsBachelor’s degree in Engineering (Mechanical, Nuclear, Electrical, or related discipline); Master’s degree preferred8+ years of progressive engineering experience, with demonstrated growth in technical responsibility and scopePrior experience serving as a system owner or lead engineer for safety‑related Nuclear Island (NI) systems on an operating or new‑build nuclear power plant strongly preferredDemonstrated experience mentoring and technically developing junior engineers, including review of designs, calculations, and system‑level deliverablesProven ability to lead multidisciplinary engineering teams, resolve highly complex technical issues, and drive system‑level decisionsStrong fundamentals in heat transfer and fluid dynamics, with demonstrated application to complex plant systemsExperience developing engineering designs, specifications, drawings, and technical requirements in collaboration with engineers, suppliers, and manufacturersExperience working in the nuclear energy industry in a system design or systems engineering capacity preferred; candidates with aerospace, defense, or other regulated‑industry systems experience also encouragedFamiliarity with engineering and design tools such as SmartPlant, Mathcad, AutoCAD, Pipe Flo, HTRI, Engineering Lifecycle Management (ELM), and requirements management tools (e.g., DOORS NG) preferredExcellent technical writing, communication, and stakeholder engagement skillsProficiency in Microsoft Office applications, particularly Word and ExcelEIT and/or PE certification preferredOur benefits go beyond the basics, reflecting our commitment to supporting your whole self…your health, your future, and your career growth.
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📌 Senior Nuclear Systems Engineer (Madrid)
🏢 Holtec
📍 Madrid