Between September 18 and November 18, 2025, a student competition was held in the Cold Crucible laboratory with the goal of designing a model for processing data from a torsional viscometer. Fifteen students registered for the competition, seven of whom advanced to the final round. The winner was Vojtěch Votruba, a student of the Faculty of Mathematics and Physics at Charles University, specializing in Theoretical Physics, whose model achieved the most accurate evaluation of the measured data.
The competing models introduced new approaches to interpreting experimental results, significantly contributing to more precise determination of viscosity at extreme temperatures. These findings have a direct impact on nuclear safety, particularly in analyzing the behavior of corium—a melt formed during a severe nuclear accident, composed of molten fuel, its cladding, and reactor structural materials.
Determining viscosity at high temperatures is extremely challenging due to the stringent requirements for measurement device durability and the limited availability of experimental data. Nevertheless, these data are crucial for predicting the spreading of corium in the core catcher and its subsequent cooling, which is essential for mitigating the consequences of an accident.
We thank all participants for their professional approach and creative proposals, which helped expand our capabilities in experimental viscosity evaluation.