Executive Assistant - Management Team, CEO & HR Support

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

At Thorizon, we are developing one of the world's most promising advanced reactor technologies. Building a company with that level of ambition requires focus, speed and excellent execution.

As Executive Assistant to our CEO, you will help create the conditions that allow our leadership team to do their best work.

You will become a trusted partner to our CEO, developing a deep understanding of priorities, ways of working and the rhythm of the business. You will help bring structure to a fast-moving environment, anticipate what needs attention before it becomes urgent, and make sure important commitments don't get lost in the pace of everyday business.

You will also play an important role in creating an outstanding employee experience in our Amsterdam headquarters by supporting key HR processes and helping our workplace run smoothly.

This is a role for someone who enjoys taking ownership, building trusted relationships and enabling others to succeed.
Much of what you do will happen behind the scenes. Its impact won't.

In this role you will:

Executive Partnership 

You will work closely with our CEO, providing proactive support that enables focus, effective decision-making and execution.

You will:

• Build a trusted working relationship with our CEO, understanding priorities, preferences and ways of working.
• Manage a dynamic calendar, balancing competing priorities and protecting time for what matters most.
• Coordinate meetings, international travel and logistics with accuracy and professionalism.
• Represent the CEO in day-to-day interactions with investors, Board members, partners, suppliers and other external stakeholders, ensuring communication is thoughtful, timely and well coordinated.
• Prepare meetings by coordinating agendas, briefing materials and action lists, helping ensure decisions are translated into execution.
• Support selected external communications, including LinkedIn.
• Anticipate issues before they arise, exercise sound judgment and help bring structure and momentum to a fast-moving organisation.

HR Support and Employee Experience 

You will help create an environment where people feel welcomed, supported and able to do their best work.

You will:

• Coordinate onboarding so every new colleague has a smooth and welcoming start.
• Support HR administration, including HR systems, pensions, payroll checks and invoice processing.
• Monitor HR, recruitment and general inboxes, ensuring questions receive timely and thoughtful responses.
• Be the first point of contact for day-to-day HR questions in our Amsterdam office.
• Help organise Town Halls, team events and offsites that strengthen our culture and bring people together.

Office Operations

You will help ensure our Amsterdam headquarters reflects the quality, professionalism and ambition of Thorizon.

You will:

• Coordinate the day-to-day operation of the office.
• Build strong relationships with building management, suppliers and service providers.
• Ensure the office is welcoming, well organised and ready for employees and visitors.
• Support workplace health, safety and compliance activities.

About you:

You enjoy making things happen.

You are someone who naturally creates order in environments where priorities evolve quickly.

You notice what needs doing before anyone has to ask.. You enjoy taking ownership, remain calm under pressure and know how to balance responsiveness with sound judgment.

You build trust through professionalism, discretion and reliability. Whether you are speaking with employees, investors, Board members or external partners, you represent Thorizon with confidence and integrity.

You communicate clearly, think ahead and enjoy solving problems. You are comfortable working independently while collaborating across functions and with people at every level of the organisation.

Most importantly, you enjoy helping others perform at their best and are motivated by contributing to something ambitious alongside exceptional colleagues.

You will bring

• Experience supporting senior executives in a dynamic, fast-paced environment.
• Experience interacting professionally with senior internal and external stakeholders.
• Experience with HR administration or employee support is an advantage.
• Excellent organisational skills and exceptional attention to detail.
• The ability to manage multiple priorities with sound judgment, discretion and professionalism.
• Fluent English (C1/C2).
• Dutch and French is a plus.
• Strong working knowledge of Microsoft 365 and experience coordinating travel and expenses.

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 closely with our CEO and leadership team, 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.