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, Spain
Primary Responsibilities Lead multi‐disciplinary system engineering and integration activities across major SMR‐300 plant systems, ensuring technical consistency and alignment across engineering disciplines
Develop and manage system requirements, interface definitions,



and component specifications to support detailed design, analysis, and licensing activities
Serve as a technical mentor to early‐career and mid‐level systems engineers, providing design guidance and reviewing calculations, specifications, and technical deliverables
Perform and oversee engineering analyses and calculations, particularly in areas related to thermal‐fluids and overall plant system performance
Conduct and support technical trade studies and design evaluations that inform high‐impact decisions affecting plant architecture, safety, and performance
Coordinate closely with licensing, safety, and regulatory teams to ensure system designs support safety case development and meet applicable codes and regulatory expectations
Collaborate with internal engineering teams, suppliers, and manufacturing partners to ensure system designs are technically sound, manufacturable, and executable
Support t

📌 Senior Nuclear Systems Engineer (Madrid)
🏢 Holtec
📍 Madrid