Irradiation of lithium zirconate pebble-bed in BEATRIX-II Phase II

Abstract

BEATRIX-II was an in-situ tritium recovery experiment that was designed to characterize the behavior of lithium ceramics irradiated to a high burnup, and to assess their suitability for use in a fusion reactor blanket. This paper describes the results from the vented canister containing 29.47 g of lithium zirconate spheres packed in a bed 13.2 mm OD, 2.3 mm ID and 103 mm long. The enriched lithium spheres (85% 6Li) were irradiated to a burnup of 5.2% (total lithium) in a steep temperature profile −400°C edge, 1100°C center. The sweep gas was He-O.1% H 2, with systematic tests using alternate compositions: He-0.01% H 2 and pure He (maximum duration 8 days). Tritium recovery decreased slightly at lower H 2 concentrations; for example, the buildup of inventory during a 4-day test in pure He was 0.8 Ci, approximately 6.5% of the tritium generated in the lithium zirconate during that period. The steadiness of the bed central temperature and the tritium release rate, together with low moisture release indicate good performance of the zirconate bed.