Most of radionuclides are soluble in high-level waste borosilicate glass and are integrated in the vitreous network. However, Ruthenium and Palladium are poorly soluble and form RuO$_2$ particles and Pd-Te beads (Fig. 1a) during the vitrification process. Ruthenium is highly conductive and forms needle-shaped particles that may change the physical properties of the glass melt. Moreover, particles containing Ru0 are sometimes observed in nuclear glasses (Fig. 1b). These particles are then bigger and denser, and Ru$^0$ is more conductive than RuO$_2$. Therefore, the unexpected reduction of RuO$_2$ in Ru$^0$ may have a significant impact on the physical properties of the melt and hinder the vitrification process.