EFFECT OF PURGE GAS OXIDIZING POTENTIAL ON TRITIUM RELEASE FROM LI-CERAMICS AND ON ITS PERMEATION THROUGH 316L SS CLADS UNDER IRRADIATION (TRINE EXPERIMENT)

The effect of red-ox potential of helium purge gas (variously doped wi th H-2, H2O and O-2) was examined on tritium release from Li-ceramics (LiAlO2 and Li2ZrO3 pellets) and on its permeation rate through the 31 6L stainless steel clads (bare and coated) held at 500 degrees C. Decr easing the H-2 content from 1000 vpm (reference 'R' gas mixture) to 10 0 vpm, and substituting H2O for H-2, the tritium permeation rate (ca. 1.410(10) atoms cm(-2) s(-1) in R-gas) increases. Tritium inventories in the Li ceramics were increased too. When a strong oxidizing purge ( 1000 vpm O-2 added to He containing 100 vpm H2O) was used, a retention time (tau) Of two days at 400 degrees C was measured for Li2ZrO3. in this oxidizing environment the tritium permeation loss dropped by a fa ctor five for the uncoated capsules while an aluminide coating became a very effective tritium barrier: tritium permeation flux at 550 degre es C fell below the measurable limit.