DIFFUSION/DESORPTION OF TRITIUM FROM IRRADIATED BERYLLIUM

[摘要] Stepped-isothermal anneal tritium release measurements at 573 up to 1173 K have been performed on irradiated Be test materials, fabricated and irradiated to meet conditions relevant to the International Thermonuclear Experimental Reactor (ITER). A combined diffusion/desorption model for tritium release allows determination of diffusion coefficients and desorption-rate constants in the mixed-mechanism regime where both diffusion and surface desorption appear to be rate-limiting. The effective tritium diffusivities (m(2)/s) for these materials, and also from new data analysis of previously reported fully dense material, were found to be 81% TD Be: 1.7x10(-11) exp(-3.4 DJ/mol/RT), 99% TD Be: 1.6x10(-1)0 exp(-9.5 kJ/mol/RT), 100% TD Be: 1.4x10(-10) exp(-11.5 kJ/mol/RT). Tritium release data for both the 81% TD and the 99% TD sample were matched reasonably well by the diffusion/desorption model. The model provides evidence for a changing mechanism over both temperature and density, but indicates that diffusion is the primary mechanism with a small and changing contribution from surface desorption.

[发布日期] 1994-09-01

[效力级别]  Proceedings Paper