Operations & Maintenance 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

Are you motivated to provide your expertise and know-how to the ongoing design studies for the innovative reactors? Are you passionate about designing cutting-edge mechanical systems and solving complex engineering challenges? Do you get energized by innovation, and transforming ideas into tangible solutions? Are you a teambuilder that can get the most out of technical experts and specialists, in an innovative and multidisciplinary development environment? 
 
You will be the work package lead of some systems in Thorizon Pioneer related to operations and maintenance and as such responsible for all activities related to design those systems in Thorizon Pioneer design and safety case. In close collaboration with internal functions – thermohydraulics, neutronics, … - you will coordinate studies you need and move the design of your system from a concept to a concrete object. Reporting to the Pioneer Project Director and Pioneer Architect, you will ensure the integration of your system within the overall reactor and manage the interface with the other systems. You will manage potential collaboration with subcontractors on design first and then on realization. In collaboration with the Safety team, you will be accountable for ensuring your system is safe and defend your case towards the regulators.  
 
You have strong experience in operations and maintenance within a nuclear environment and are able to design human operations, specific equipment, and associated activities for safe and efficient execution. You are familiar with radioprotection codes and standards (e.g., IAEA, EURATOM, or local regulations) and know how to implement the ALARA methodology to minimize radiation exposure. Your expertise includes developing operational procedures, defining technical requirements for tools and equipment, and ensuring compliance with safety, waste management, and regulatory frameworks to support seamless project execution. 
You are able to self define your weekly routine. You have a strong spirit of team effort and as such able to maneuver in cross-functional teams. You have a high level of communication skills and stakeholder management. 
This role is based in Amsterdam, Netherlands or in Lyon, France.

In this role you will:

• Define operations and maintenance operations within Thorizon Pioneer, with associated codes and standards, and apply the ALARA methodology.

• Define, validate, and verify (functional) requirements for associated systems of Thorizon Pioneer; optimize the design to deliver on those requirements; and manage trade-offs within the design envelope (e.g., reliability, performance, lifetime, costs) while continuously ensuring maximum safety and preparing for the realization of these systems.

• Work in a cross-functional team within the Pioneer project (typically a project-based team of ~3–6 engineers from different disciplines such as nuclear engineering, core physics, thermal hydraulics, and chemistry).

• Conduct engineering work for your work package (e.g., component and system design, computer models, and analyses to simulate safety and performance).

• Initiate projects with our expert engineers who support you with analyses, validation, verification, and qualification.

• Select, qualify, and manage external contractors who support you in your mission.

• Deliver system documentation, prepare design reviews, and ensure system integration.

• Build documentation and presentations to enable licensing discussions with safety authorities.

• Support program management by coordinating meetings, communicating with external partners, and leading specific projects.

• Participate in meetings with regulators with the aim of defending in-house positions and contribute to maintaining an active dialogue with regulators (in particular ASNR, ANVS, and FANC).

• Work very closely with the Pioneer Architect, Functional Leads and team, the Program Office, COO, CTO, and the rest of the teams in Lyon and Amsterdam.

• Report to the Pioneer Project Director, in the COO line.

About you:

• Master's degree and proven experience in nuclear operations, maintenance, dismantling, or waste management (10+ years).
• Knowledge and understanding of the following disciplines are required: mechanical engineering, neutronics, chemistry (corrosion), thermodynamics, and structural engineering.
• Experience with systems engineering approaches is a plus.
• Able to connect strategy, design requirements, and execution in a complex multidisciplinary environment.
• Capable of managing technical trade-offs while maintaining focus on safety, performance, reliability, and operability.
• Fast learner with the ability to lead complex technical topics and navigate uncertainty.
• Strong stakeholder management, communication, and interpersonal skills.
• Able to work effectively across functions, disciplines, and organizations.
• Takes ownership of deliverables and drives topics through to completion.
• Solution-oriented, proactive, and motivated by pioneering challenges.
• Strong organizational skills, attention to quality, and ability to manage multiple priorities.
• Comfortable working in a diverse international environment and adapting approach to different situations and stakeholders.
• Excellent communication skills in English, both written and spoken.
• French and/or Dutch would be a strong plus.
• Willing to travel between Lyon and Amsterdam.

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