Nuclear fission is experiencing renewed interest as a low-carbon energy source capable of supporting the energy transition. In particular, Small Modular Reactors (SMRs) are attracting considerable attention due to their potential to provide not only reliable electricity generation but also industrial heat production.
Many industrial sectors are seeking alternatives to fossil fuels for process heat. SMRs could play a key role in this transition. However, future energy systems will require reactors to operate more flexibly than traditional baseload nuclear plants. Variations in electricity prices, renewable energy availability, and industrial heat demand may require frequent changes in reactor operating conditions. Understanding how these transients affect reactor behavior, thermal-hydraulic performance, and safety margins is therefore a critical research challenge.
KU Leuven is offering a four-year PhD position to contribute to this emerging field.
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Project
The PhD research is part of FLEX-SMR, a project funded by the Belgian Federal Government through the Energy Transition Fund. The project is a collaboration between KU Leuven, The Binding Energy (TBE), and INOVYN Manufacturing Belgium.
The overall objective of FLEX-SMR is to develop cost-optimal solutions for integrating SMRs into industrial energy systems. In particular, the project investigates how an SMR can be operated together with other energy assets, such as electrical boilers, within a Model Predictive Control (MPC) framework that optimally balances electricity and heat production.
Within FLEX-SMR, this PhD focuses on the nuclear engineering aspects of flexible reactor operation. The work combines reactor physics, thermal-hydraulics, model reduction, and control design.
The main research objectives are:
- Development of a high-fidelity dynamic SMR model. Develop and validate advanced dynamic models of a PWR-type SMR, incorporating both reactor physics and thermal-hydraulic phenomena. This task will be performed in close collaboration with TBE.
- Reduced-order and AI-based modelling. Investigate techniques to accelerate reactor simulations for system-level integration and real-time applications. Potential approaches include reduced-order modelling, surrogate models, and machine-learning methods such as neural networks.
- Control design for flexible reactor operation. Develop advanced control strategies that enable safe and efficient reactor operation under time-varying electricity and heat demand while respecting operational and safety constraints.
Research environment
The PhD research will be conducted at the Department of Mechanical Engineering at KU Leuven. The PhD candidate will be supervised by Prof. Niels Horsten, who leads the thermal-hydraulics research activities on SMRs at KU Leuven. The candidate will become part of a growing research effort on advanced nuclear energy systems and will regularly interact with industrial and academic partners involved in the FLEX-SMR consortium.
Profile
We are looking for a highly motivated and enthusiastic researcher with a strong interest in nuclear engineering and advanced modeling techniques.
You have:
A Master's degree in Engineering (or equivalent) with a background in nuclear engineering, mechanical engineering, energy engineering, applied physics, or a related discipline, from a reputable institute, with at least distinction.
A solid background in one or more of the following areas:
- numerical modelling
- heat and mass transfer
- fluid mechanics
- reactor physics
A strong interest in scientific computing and simulation.
The qualities to carry out independent research, demonstrated, e.g., by the grades obtained on your MSc thesis.
Excellent written and spoken English skills.
A critical mindset.
The following qualifications are considered advantageous:
- Knowledge of reactor dynamics modeling
- Experience with system thermal-hydraulic (STH) approaches such as implemented in RELAP5, ATHLET, and many other STH codes
- Familiarity with machine learning or reduced-order modeling
Offer
- A doctoral scholarship of four years and, if successful, a PhD in Engineering Science
- A competitive salary and additional benefits such as health insurance, access to university sports facilities, etc.
- The opportunity to be active in an exciting and international research environment, engage in research collaborations and participate at international conferences
- A full-time employment for four years, with an intermediate evaluation after one year
- An excellent doctoral training at the doctoral school. This will allow you to gain the skills required to successfully complete your PhD, as well as develop yourself as an independent researcher. Moreover, opportunities are provided to acquire deeper knowledge in subjects related to the topic by participating in trainings, summer schools, or lecture series in- and outside of KU Leuven
- A flexible working culture with opportunity to up to 40% remote working
- The selected candidate will be encouraged and supported to apply for an FWO PhD fellowship.
The intended starting date is November 2026, although an earlier or later starting date can be discussed.
Interested?
Applicants should express their interest by sending an email to Prof. Niels Horsten via [email protected]. The email should strictly contain the following information in the text body, in bullets:
Name
Preferred form of address (e.g., Mr., Ms., Mx., or another title)
Master degree (Master specification, University + Country, Year obtained, Promotor)
Master thesis title
A one paragraph (up to half an A4 page) statement explaining the motivation for applying for this vacancy at KU Leuven.
Please also attach an academic CV and a PDF of your diplomas and transcript of course work and grades.
Please submit applications directly by email to Prof. Niels Horsten. Applications submitted exclusively via the KU Leuven online platform may not be considered. Note that if you do not receive a response to your email within three weeks, this means you have not been selected for the second stage. Decision: as soon as a suitable candidate applies (so do not wait until the closing date to apply).
For more information, please contact Prof. Niels Horsten at [email protected].
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