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 technical reviews, design documentation development, and internal design approval processes in alignment with program milestones and quality standards
- Serve 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 rigor

Requirements

- Bachelor’s degree in Engineering (Mechanical, Nuclear, Electrical, or related discipline); Master’s degree preferred
- 8+ years of progressive engineering experience, with demonstrated growth in technical responsibility and scope




- Prior 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 preferred
- Demonstrated experience mentoring and technically developing junior engineers, including review of designs, calculations, and system‑level deliverables
- Proven ability to lead multidisciplinary engineering teams, resolve highly complex technical issues, and drive system‑level decisions
- Strong fundamentals in heat transfer and fluid dynamics, with demonstrated application to complex plant systems
- Experience developing engineering designs, specifications, drawings, and technical requirements in collaboration with engineers, suppliers, and manufacturers
- Experience 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 encouraged
- Familiarity 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) preferred
- Excellent technical writing, communication, and stakeholder engagement skills
- Proficiency in Microsoft Office applications, particularly Word and Excel
- EIT and/or PE certification preferred

Our 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