Effects of heavy-ion irradiation on Gd2Zr2O7 bearing simulated TRPO waste

Considering the urgent demand of nuclear waste disposal, a comprehensive study on the irradiation performance of nuclear waste forms is extremely necessary, especially on those containing multiple-nuclides with multiple-valence. The irradiation effects of Gd 2 Zr 2 O 7 pyrochlore bearing simulated trialkyl phosphine oxides (TRPO) waste (consisting of ZrO 2 , MoO 3 , RuO 2 and PdO) were studied in this work. Gd 10.685 Mo 4.734 Zr 28.924 Ru 1.000 Pd 1.745 O 91.825 and Gd 8.883 Mo 9.901 Zr 33.760 Ru 2.089 Pd 3.644 O 118.368 were irradiated by 1.5 MeV Xe 20+ to fluences from 1 × 10 12 to 1 × 10 15 ions/cm 2 at room temperature. The results showed an irradiation induced disordering with slight micro-swelling. In addition, the ion irradiation tolerance of the solid solutions decreased as the TRPO waste content increased. The decrease and shift of Raman peaks indicated the structural disordering and inner stress after irradiation. The micromorphology and element distribution of the irradiated surface remained almost unchanged. The structural evolution from pyrochlore to fluorite and even amorphous structure were disclosed in this study.