IT System Administrator

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

Thorizon runs a modern, cloud-first IT environment built on Microsoft 365 and Azure. It is designed for an AI-driven way of working and for the security and sovereignty requirements of the nuclear sector. 
As our System Administrator, you are the hands-on owner of that environment. You make sure our engineers, scientists and support teams in Amsterdam and Lyon can work securely and without friction, every day. You will continuously improve the environment through automation and good documentation. 
Roughly two thirds of the role is operations, security and service, and one third is improvement and automation projects. Over time, there is room to grow towards cloud and platform engineering. 
You will report to our Data & AI Director and work closely with external partners and vendors and with our engineering teams. 
This role is based in Amsterdam, The Netherlands.

In this role you will:

• Administer and secure our IT environment:
  • You will administer and continuously improve our Microsoft 365 and cloud environment, including identity and access, devices, and tooling for collaboration and security.
  • You will operate our zero-trust and secure-access setup and investigate and follow up on security alerts. You will also maintain endpoint security, patching and logging.
  • You will manage office networks, printing and meeting rooms at both sites, together with local partners where needed.
  • You will make sure backup, monitoring and recovery are in place and tested.
• Run IT operations and support:
  • You will run and mature our IT operations, including the service desk, onboarding and offboarding, device lifecycle and asset management, licensing, and incident, change and problem management.
  • You will be the go-to person for colleagues with IT questions. You will solve issues yourself or coordinate with vendors, and you will help raise digital literacy across the organisation.
  • You will manage key IT suppliers and service partners, and you will keep licensing and costs under control.
  • You will document systems, procedures and decisions so that knowledge does not live in one person’s head.
• Protect what matters:
  • You will support our information security function in policies, access reviews, risk assessments, vulnerability management, audits and security incidents.
  • You will ensure that systems, data storage, and remote and vendor access comply with export control requirements (EU dual-use regulation) and with the integrity and traceability expectations of a safety-critical environment.
• Automate and grow:
  • You will replace manual work with scripted and repeatable solutions, using PowerShell, Intune and Entra configuration, and increasingly infrastructure as code.
  • You will support the IT side of engineering platforms, such as CAD and version control systems, simulation and data environments, and secure environments for AI tools. You will work together with the people who build and use them.
  • This is a role where success depends on reliable, secure systems and satisfied colleagues in a fast-moving engineering environment, not on perfect designs.

About you:

• You enjoy owning an environment end to end, from fixing a laptop to tightening a conditional access policy, and you are motivated to make things more automated and secure each month.
• You bring:
  • 3 to 10 years of experience in system administration or IT engineering, ideally in a growing, technical or regulated organisation.
  • Strong hands-on experience with Microsoft 365, Entra ID and Intune, and working knowledge of cloud computing.
  • A solid grasp of security fundamentals, including identity and access management, endpoint security, patching and zero-trust principles.
  • Scripting skills in PowerShell, or comparable skills in Python or Bash.
  • Fluency in English.
  • Experience with the following is a plus: Infrastructure as Code, Git, CI/CD, HCP and SASE or ZTNA platforms. So is experience in nuclear, defense, aerospace or other export-controlled or safety-critical industries, and knowledge of Dutch or French.
• Beyond technical skills, how you work is critical:
  • You work with openness: you make assumptions explicit, document what you build, and engage constructively with disagreement.
  • You take responsibility: you own problems end to end and do not depend on perfect organisational clarity to act.
  • You contribute to unity across teams: you serve colleagues across disciplines and both sites, and you explain technology in plain language.
  • You are pragmatic: you choose solutions that fit a ~50-person company with a credible path to scale, and you avoid unnecessary complexity.
• What makes this role unique:
  • You will be the hands-on owner of the IT environment of a nuclear deep-tech company at a formative stage, with real influence on tooling and security choices.
  • You will work directly with engineers who design a new reactor system, in a sector where integrity, security and sovereignty truly matter.
  • You will have a clear path to grow into cloud, platform or security engineering as the company grows.

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.