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Sintering kinetics and mechanisms in UO2 and MOX nuclear fuels for LFR-SMRs

  • //applyindex.com/wp-content/uploads/2021/11/belgium.png Belgium
  • University/Institute Name KU Leuven
  • Attendance Type On Campus (Full Time)
  • Position DurationSee Position Description
  • Position Funding Type PhD Research Funding
  • Application deadlineMarch 31, 2026
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Position Details (PhD Research Project)

The researcher will be active in the expert group on Fuel Materials at the Belgian Nuclear Research Centre (SCK CEN) in Mol.
The daily supervision of the PhD will be done by SCK CEN Mentor Gregory Leinders ([emailprotected]) and SCK CEN Co-mentor Frédéric Jutier ([emailprotected]).
The University promotor will be Prof. dr. ir. Jozef Vleugels ([emailprotected]) from the Department of Materials Engineering of KU Leuven.

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Project

Small Modular Reactors (SMRs) are reshaping the future of nuclear energy, offering scalable, safe, and low-carbon solutions. Among these, Lead-cooled Fast Reactors (LFRs) stand out for their passive safety and efficient actinide management. The European EAGLES-300 initiative aims to commercialize a 350 MWe LFR-SMR by 2039, requiring advanced fuel technologies.High-plutonium content (20–30 wt.% Pu/[U+Pu]) mixed-oxide (MOX) fuel materials which are required for LFR-SMRs present fabrication challenges. Conventional sintering methods, developed for light-water reactor MOX, are inadequate due to altered thermodynamic behavior. Optimal sintering parameters are essential but complex to define, especially under industrial conditions using continuous furnaces with variable atmospheres. Even minor deviations in oxygen potential can lead to out-of-specification fuel pellets. Furthermore, the fuel microstructure, density, porosity, and stoichiometry, which are vital parameters for in-pile performance and licensing, are critically influenced by the sintering conditions.

This PhD research aims to address these complexities by investigating the sintering kinetics and mechanisms of UO2 and high-Pu MOX fuel materials. The scientific objectives focus on characterizing powder properties and their influence on pellet formation, examining the effects of additives and manufacturing routes on fuel pellet microstructure, and investigating densification, grain growth, and sintering behavior through both batch and in-situ techniques. Ultimately, the goal is to improve our understanding on how sintering time, heating rate, and gas atmosphere collectively impact the final pellet quality.

The project will be conducted in SCK CEN’s fuel laboratories using powder metallurgical methods. Liquid-to-solid and thermal conversion techniques will be applied to produce uranium and plutonium precursors and oxide feed powders. Pellets will be fabricated by compacting powders using hydraulic or electromechanical presses, and sintering experiments will be performed, with specific attention to accurate temperature and gas atmosphere control. Solid-state characterization will involve optical and electron microscopy, particle size and surface area analysis, density measurements, and X-ray diffraction. In-situ techniques such as thermogravimetric analysis and dilatometry will be applied, complemented by microstructural examination using electron probe microanalysis.

Profile

Master of Sciences, Master of Sciences in Engineering, Master in Nuclear Engineering, Master in Materials Engineering, or an equivalent master degree. The candidate preferably has a background in materials science, physico-chemistry.

The candidate will have to pass the selection campaign of the Scientific Council of SCK CEN, by an oral defense of the research theme on May 21 or 22, 2026.

Before applying, please consult the SCK CEN guidelines for application for PhD.

Deadline for application:March 31, 2026

Notification for oral interviews (if selected): May 4, 2026

Oral presentations:May 21 and 22, 2026

Notification of final decision:June 15, 2026

Start at SCK CEN:October 1, 2026

Offer

Ph.D. fellowship for the duration of a maximum of 4 years.The candidate will obtain a Ph.D. in Engineering Science - Materials Engineering at the Faculty of Engineering of KU Leuven.

Department of Materials Engineering of KU Leuven
KU Leuven
Belgian Nuclear Research Centre (SCK CEN)
SCK CEN guidelines for application for PhD

Interested?

For more information please contact:

Prof. dr. ir. Jozef Vleugels, tel.: +32 16 32 12 44, mail: [emailprotected].
SCK CEN Mentor: Dr. Gregory Leinders, tel.: +32 14 33 31 40, mail: [emailprotected]
SCK CEN Co-mentor: Dr. Frédéric Jutier, tel.: +32 14 33 32 24, mail: [emailprotected]

KU Leuven strives for an inclusive, respectful and socially safe environment. We embrace diversity among individuals and groups as an asset. Open dialogue and differences in perspective are essential for an ambitious research and educational environment. In our commitment to equal opportunity, we recognize the consequences of historical inequalities. We do not accept any form of discrimination based on, but not limited to, gender identity and expression, sexual orientation, age, ethnic or national background, skin colour, religious and philosophical diversity, neurodivergence, employment disability, health, or socioeconomic status. For questions about accessibility or support offered, we are happy to assist you at this email address.

Research Areas & Fields of Study involved in the position

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