Postirradiation examination of BEATRIX-II, phase I

Abstract

BEATRIX-II is an in-situ tritium recovery experiment that was designed to characterize the behavior of lithium ceramics irradiated to high burnup in a fast neutron flux. Postirradiation examination was carried out on the Phase I vented canisters: one containing a Li 2O ring capable of temperature changes and the other a Li 2O solid specimen with a center temperature of 1000°C. The tritium inventory of the ring specimen at 630°C was determined to be in the range from 0.2–0.6 wppm, while for the solid specimen the inventory varied from 1.4 wppm at the surface to 0.06 wppm at the inner surface. Downstream transport of the Li 2O by the sweep gas was determined to be insignificant from analyses of acid rinses of selected canister surfaces. Densification and restructuring of the solid specimen during irradiation resulted in the development of a central annulus. Ceramography was used to characterize the columnar grain structure and the mechanisms involved in its evolution.