Mechanical calculations 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 mechanical calculation work for a system or part of the system related in Thorizon’s reactor design. You will be a key person of the calculation 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 deliverables with calculation specification, calculation strategy and hypothesis and calculations notes within the performance, cost, and time constraints of our project. 

In this role you will:

Within this general framework, you will own your activities to ensure the quality and validity of the studies and work performed and develop mechanical calculation 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 calculation 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 calculation tools and for maintaining high-quality, reliable studies. 
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 degreeand proven experiencein mechanical engineeringcalculations(5years).
• Essential experience in FEM simulation and calculation analysis like linear structural analysis, structural seismic response, thermalstressand fatigue of at least 5 years with a confirmed or even expert levelwithABAQUSand/orANSYSsoftware.
• Essential experience with application of code ASME III and/or RCC-M of at least 3 years.
• Good knowledge of design engineering by calculation approach, ,which you combine with a practical approach, supporting design team.
• Good knowledgeexperience in CAD practices.
• Good knowledgeinofficetool applications.
• You get inspired by anorganizationwith a large variety of people, with different experiences andbackgrounds,andhave the ability toadjust yourworkingstyle depending onthesituationandthepeople involved: you are agile but rigorous.
• You are eager to learn and like challenges.
• You rethink issues to find practical solutions to difficultproblems,and youdemonstrateagility byminimizingcomplexity. You have a pragmatic and constructive mindset.
• You are rigorous and autonomous in your field ofexpertise
• You have a good sense of judgement: you think strategically (in your field andconsiderall the dimensions of the project), and you know how toprioritizeyour 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