IDENTIFIKASI FASA PADA PELET BAHAN BAKAR U-ZrHx HASIL PROSES SINTER DENGAN ATMOSFER NITROGEN

Abstract

Phases identification of U-ZrH_X  fuel pellets sintered under nitrogen atmosphere has been carried out. This sintering process is intended to obtain higher density pellets that meet the requirements for use as a fuel in pressurized water reactor (PWR). The results of this study are expected to be used for the determination of phase and density changes occurred in U-ZrHx pellets at various Zr concentrations after sintering at various temperatures. PWR fuel from U-ZrHx pellet needs to be sintered to increase its density. At first, pellets made from U-ZrH_x powder with Zr composition of 35, 45 and 55 wt.% through a pressing process at a pressure of 509-637 MPa. The resulted U-ZrH_x green pellets were subsequently sintered under nitrogen gas atmosphere at 1200 °C and 1300 °C for a fixed sintering time of one hour.  Phase analysis of the sintered U-ZrH_x pellets was done by X-ray diffraction (XRD) technique and the data obtained were processed by using  HighScore Plus software. The test results with XRD indicate the formation of phases such as U(ZrHr₂), UO₃, UO₂, and Zr. The UO₂ and Zr phases were characterized for their density, lattice parameter and percentage of weight. In this experiment it is desired to obtain U-ZrH_x with high density without the formation of many phases. Density measurement shows that the density of zirconium metal and UO₂ decreases with increasing sintering temperature (from 1200 °C to 1300 °C), while the lattice parameter increases with increasing sintering temperature. Data calculation of weight percentage for sintering at 1300 °C shows that the percentage values of the resulted zirconium metal and uranium dioxide are the closest to their theoretical calculation results.