Further examination of irradiated hot-pressed beryllium oxide based fuel specimens.

Abstract

The work reported in AAEC/E106 on the metallographic examination of (U,Th)02 dispersed in BeO irradiated in a thermal neutron flux is extended. X—ray diffraction studies have demonstrated that strain developed in the matrixes of both coarse and fine dispersions during irradiation was more severe in the fine dispersion. It is thought that in the coarse dispersion it arose from the swelling of fuel particles and in the fine dispersion, from fission fragment damage. The strain was relieved by annealing in the range 1000 — 1350ºC and was partly relieved in the coarse dispersion by crushing. Fission gas bubbles were observed in the microstructure of specimens annealed at 1250ºC and 1500ºC after irradiation.