Mechanical 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

You will be responsible for mechanically design a system or part of the system related in Thorizon’s reactor design. You will be a key person of the mechanical expertise center, whose primary missions are, on the one hand, to provide expertise in this area to the system in charge of the reactor design studies and, on the other hand, to define, execute, and deliver the mechanical studies with drawings, part lists, specifications for manufacturing and supplying within the performance, cost, and time constraints of our project. 

Within this general framework, you will own your activities to ensure the quality and validity of the studies and work performed, and develop mechanical expertise in line with the needs of the Thorizon project and its future developments. Concretely, you support system design teams (from PILOT to FOAK/NOAK) by providing deep mechanical engineering input and ensuring that all design choices are technically sound and consistent with requirements and applicable Codes & Standards. You take responsibility for the correct use of design tools and for maintaining high-quality, reliable engineering studies. 

In this role you will:

​​​​A key part of your role is to ensure strong interfaces between mechanical engineering and the wider organization: system design, project teams, licensing, safety, functional leads, and management.  

Your level of expertise allows you to prioritize based on the importance of the needs, and as an expert, you have the power to recommend any necessary actions for the project related to your area of expertise. 

Furthermore, you participate in external networks, including international initiatives, to stay at the forefront of industry development.
In this environment, you get the unique opportunity to put your knowledge to the best use, develop your ideas, explore various aspects of mechanical engineering, and play a crucial role in the company’s growth. 

About you:

• Master's degree and proven experience in mechanical engineering (5 years). 
• Essential experience in CAD practices (2D and 3D) of at least 5 years with a confirmed or even expert level. 
• Good knowledge of structural and thermos-mechanical analyses methods, design by rules and quality assurance, which you combine with a practical approach, supporting realization. 
• Good knowledge and proven application of Codes and Standards and regulations (RCC-MRx, ASME, ESPN…). 
• Good knowledge in office tool applications. 
• You have experience in industrial mechanical systems such as pressure vessels, piping systems, large mechanical components, and handling equipment. 
• You get inspired by an organization with a large variety of people, with different experiences and backgrounds, and have the ability to adjust your working style depending on the situation and the people involved: you are agile but rigorous. 
• You are eager to learn and like challenges. 
• You are creative and innovative: You rethink issues to find practical solutions to difficult problems, and you demonstrate agility by minimizing complexity. You have a pragmatic and constructive mindset. 
• You have a good sense of judgement: you think strategically (in your field and consider all the dimensions of the project), and you know how to prioritize your actions according to the key issues at stake. 
• You have excellent communication skills: you listen before you react, you are concise, you treat people with respect, you keep calm in stressful situations, you have excellent writing skills. You are an excellent communicator in English, and preferably also French or Dutch, both spoken and written.  
• You create impact: your productions are models for your colleagues. 

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