Corrosion tests of triuran disilicide fuel pellets

The study aims to determine the corrosion stability of triuranium disilicide pellets under the conditions similar to small-nuclear plant (SNPP) modes. For this, corrosion tests were carried out in comparison with uranium dioxide in zirconium mini-autoclaves with distilled (deionized) water at a pressure of 16.2 MPa using a Nabertherm muffle furnace (Germany) at a temperature of 331 ± 3 °C and isothermal exposure of 4 and 10 h. The temperature of isothermal sections was calibrated and controlled using a rhenium-tungsten thermocouple located near the mini-autoclaves. After a 4h exposure, the surface of the triuranium disilicide sample was slightly oxidized without destruction. After 10 h, it was oxidized with a slight detachment of fine particles. The mass gain of the sample together with exfoliated fine particles comprised 0.5% (25 mg). No uranium dioxide was detected on the standard fuel pellet under these oxidation modes.