Neutronics internship - Assessment of reactor physics experimental integral data knowledge for chloride based nuclear reactors

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

The main objective of the internship is to identify, analyze, and critically assess existing reactor physics experimental integral data relevant to the project’s scope (e.g. k-eff, reaction rates, ...). The results will contribute to a better understanding of current data limitations and uncertainties, and help guide modelling, simulation, and experimental efforts within the project.

In this role you will:

Main Tasks 

• Perform a comprehensive literature review of experimental integral data from journals, technical reports, and databases (e.g. IRPHE, ...).
• Identify key experiments, measurement techniques, and associated uncertainties.
• Compare experimental results with calculated results and give an interpretation of the comparison where relevant.
• Assess the consistency, reliability, and applicability of available data for the targeted innovative application.
• Summarize findings in clear technical reports and presentations.
• Propose recommendations for data selection, further analysis, or future experimental needs.

By the end of the internship, the candidate will have: 

• Developed a structured and critical overview of experimental integral data relevant to an advanced nuclear project.
• Gained hands-on experience with experimental databases and neutronics calculations.
• Contributed directly to an innovative research and development effort.
• Built strong foundations for further work in integral data evaluation, reactor modelling, and experimental techniques.

About you:

• Master’s-level student (or final-year undergraduate) in nuclear engineering, physics, ora relatedfield.
• You are passionate about neutronics andwilling to merge existing knowledge into the Thorizon reactors.
• Strong analytical skills and ability to synthesize complex technical information.
• Familiarity with neutronics key concepts,data bases and automation skills (Python) is highly desirable.
• Excellent communicator (clear is kind) in English both spoken and written. French or Dutch is a plus.
• Strong organizational and multitasking abilities, with attention to detail and accuracy.
• You like working in an agile manner and are comfortable at the fast-moving pace of a technological scale-up.  

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.
• The expected salary conditionsare of 600 €/month.
• The expected duration of the internshipis of 5-6months starting as of 1st of September 2026 (start date can also be changed depending on the needs of the candidate).