Senior System Engineer

Thorizon is a European developer of next-generation small modular reactors (SMRs) based on molten salt technology. The company builds compact, modular nuclear reactors designed to deliver reliable baseload power and high-temperature industrial heat for sectors such as manufacturing, data centers, and energy-intensive industry. Spun off from NRG, the Netherlands' national nuclear research institute, Thorizon is commercializing molten salt reactor technology that was developed over decades of quiet research. The company aims to begin reactor construction in the early 2030s, with designs optimized for series production and flexible deployment close to end users. Thorizon's mission centers on providing clean, affordable, and safe nuclear energy without compromise. A defining feature of its technology is the use of existing nuclear waste as fuel, dramatically improving fuel efficiency and reducing the long-term waste burden of nuclear power. The company's patented cartridge system divides the reactor core into smaller, factory-produced modules, enabling off-site manufacturing, faster construction timelines, and true modular scalability. Operating at low pressure, the reactors offer an intrinsically safer profile compared to conventional nuclear designs. Thorizon has secured investment and signed a memorandum of understanding with partners including EPZ and NRG PALLAS, as well as provincial authorities, to build Europe's first commercial molten salt reactor in the Netherlands. The company has also received recognition for innovation, winning the ASML Emerging Innovator Award. By working with partners across engineering, fuel production, operations, and financing, Thorizon is positioned to scale its reactor technology to meet the growing demand for clean, dispatchable energy.

Your mission

Help realize one of the world's most promising reactor technologies. 

As a Senior System Engineer, you will play a key role in the development of Europe's first nuclear molten salt reactor demonstrator. You will take ownership of one or more systems that are essential to the success of the reactor and guide their development from concept to integrated design. You will bring together experts from different engineering disciplines, translate technical challenges into clear engineering solutions, and drive decisions that balance performance, safety, reliability, manufacturability and cost. 
 
This role is about mastering complexity. It requires systems thinking, engineering judgment and the ability to create alignment across multidisciplinary teams. We are looking for engineers who have solved complex engineering challenges and are excited to apply their expertise to a new technological frontier. 

In this role you will:

• Leadthe development of one or more major systems within the Thorizon Pioneer programme. 
• Define, validate and manage system requirements throughout the design lifecycle. 
• Drive system architecture, integrationand interface management across multiple engineering disciplines. 
• Balance technical trade-offs between performance, safety, reliability, operability, manufacturabilityand cost. 
• Coordinate multidisciplinary engineering activities and bring together specialists to develop integrated solutions. 
• Initiateand guide analyses, simulations, testing and design activities needed to mature your systems. 
• Identify technical risks, challengeassumptionsand drive engineering decisions based on evidence. 
• Plan and coordinate verification and validation activities to demonstrate that systems meet their intended functions. 
• Deliver system documentation, prepare design reviews and contribute to licensing documentation.
• Collaborate closely with architects, technical leads, projectmanagement and external partners to ensure successful integration of your systems. 
• Contribute to the continuous development of Thorizon's systems engineering practices. 

About you:

• You enjoy solving problems that have never been solved before.
• You are comfortable working at the intersection of multiple engineering disciplines and know how to bring structure to technical complexity. You combine analytical thinking with pragmatism and know how to move engineering work forward by bringing people together.
• You probably hold a Master's degree in Engineeringor another relevant technical discipline. 
• You have significant experience developing complex engineered systems or products. 
• Experience in systems engineering, systems integrationor and technical leadership within a multidisciplinary engineering environment. 
• Experience in industries such as aerospace, defense, energy, industrial equipment, automotive, marine, process industries, or other complex engineering sectors. Nuclear experience is an advantage, not a requirement. 
• A strong understanding of systems engineering principles, including requirements management, interface management, integration,verification and validation. 
• The ability to balance competing technical objectives and make sound engineering trade-offs. 
• Strong communication and stakeholder management skills, with the ability to influence across disciplines and levels of expertise. 
• Curiosity, ownership and the ambition to contribute to pioneering technology. 
• Excellent written and spoken English. 
• Willingness to travel occasionally between our Amsterdam and Lyon offices. 

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What you can expect from us:

• The opportunity to help realize the most promising reactor technology and advance Europe's energy future.
• Being part of an exceptional team that combines engineering rigor, scientific excellence, and entrepreneurial drive.
• Working in multidisciplinary teams on ambitious missions, with responsibility and meaningful impact from day one.
• A fast-moving deep-tech environment where initiative is valued and people are trusted to make decisions.
• Complex, multidisciplinary challenges that will stretch you and accelerate your growth.
• Competitive compensation and participation in our employee profit-sharing plan.
• An international workplace with offices in the heart of Amsterdam and Lyon.