Public thesis defense Tommy MAI - ICTEAM
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Thermal conductivity measurement methods for dispersion MTR fuel characterization
Monday August 31st, 2026 - 4:15pm - Auditorium: LAVO 52 - Bâtiment Lavoisier, Pl. Louis Pasteur 1, 1348 Louvain-la-Neuve
The thermal characterization of HALEU composite fuels, such as U₃Si₂-Al dispersion fuels for MTR applications, requires advanced techniques to evaluate thermal conductivity across multiple length scales and burnup conditions.
This work developed and evaluated two thermoanalytical methods for characterizing the thermal conductivity of MTR fuel specimens: an adapted MALDONADO pulse-heating approach for bulk measurements and a dedicated microelectromechanical systems thermal suspended bridge (MEMS-TSB) device for microscopic characterization.
The investigation demonstrated that the MALDONADO measurement principle could, in principle, be adapted to a planar sample geometry, representing a first-of-its-kind implementation. Furthermore, the applicable temperature range could theoretically be extended to temperatures exceeding 200 °C. The analytical framework underlying the method was described in greater detail than previously reported in the literature. However, the developed prototype did not enable quantitatively reliable measurements due to several identified design limitations.
For the microscopic thermal conductivity characterization, a MEMS-TSB platform was newly designed and fabricated at the WINFAB facility of UCLouvain. A simplified yet comprehensive manufacturing process was established, including the novel implementation of XeF₂ dry etching as an improved release strategy, together with a compatibility assessment of suitable SiNₓ materials. The resulting batch-fabrication and backend-processing route yielded highly robust devices with a manufacturing yield approaching 100%, ultimately leading to an off-the-shelf like measurement platform. In support of the implementation of the system, a specimen preparation route for micro-rod samples derived from bulk reference materials was also developed at SCK CEN. Experimental measurements were successfully performed on a 316L stainless steel specimen, thereby demonstrating the functionality of the developed MEMS-TSB device. Nevertheless, precise quantitative measurements could not yet be achieved due to limitations associated with the vacuum environment of the utilized test stand.
Jury members
Prof. Thomas Pardoen (UCLouvain), Supervisor
Dr. Sven Van den Berghe (PanTera & Ghent University), Supervisor
Prof. Renaud Ronsse (UCLouvain), Chairperson
Prof. Jean-Pierre Raskin (UCLouvain), Secretary
Prof. Denis Flandre (UCLouvain)
Dr. Ann Leenaers (SCK CEN)
Dr. Tsvetoslav Pavlov (Idaho National Laboratory)
Mr Jared Wight (SCK CEN)