Neutron irradiation damage in Al2O3 and Y2O3

Two ceramics under consideration for use in fusion reactors, Al2O3 and Y2O3, were irradiated in the EBR-II fission reactor at 650, 875, and 10250K to fluences between 2 and 6 x 1021 n/cm2 (E greater than 0.1 MeV). Samples evaluated include sapphire, Lucalox, alumina, Y2O3, and Y2O3-10 percent ZrO2 (Yttralox). All Al2O3 specimens swelled significantly (1 to 3 percent), with most of the growth observed in sapphire along the c-axis at the higher temperatures. Al2O3 samples irradiated at 875 and 10250K contained a high density of small aligned ''pores''. Irradiated Y2O3-based ceramics exhibited dimensional stability and a defect content consisting primarily of unresolved damage and/or dislocation loops. The behavior of these ceramics under irradiation is discussed, and the relevance of fission neutron damage studies to fusion reactor applications is considered