Spatial tritium transport in single-crystal lithium aluminate

• Published in: Journal of nuclear materials Vol. 212; pp. 912 - 916
• Main Authors: Kopasz, J.P., Seils, C.A., Johnson, C.E.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.1994
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/0022-3115(94)90968-7

Isothermal anneal tests have been performed on large single-crystal samples (approximately 1.5 mm diameter) of LiAlO 2 in an attempt to determine the diffusivity of tritium in lithium aluminate. To understand the effects of impurities on the tritium transport, single crystals of Mg-doped LiAlO 2 were also studied. The crystals were sectioned after annealing to determine the tritium concentration profiles within the crystals. From these profiles the tritium diffusivity, D, and the desorption rate constant, K, were calculated. The tritium diffusivities determined for the doped and undoped materials were the same within experimental error. The measured diffusivity is given by ln D( 2/s) = −11.8 - (1.50 × 10 4)/ T. Tritium release for these samples was generally in the mixed diffusion-desorption regime, as determined from the ratio aK D , where a is the grain radius. Our data indicate that for grain radii less than 100 μm, the tritium transport will be in the desorption-controlled regime.