TRITIUM RELEASE FROM BERYLLIUM DISKS AND LITHIUM CERAMICS IRRADIATED IN THE SIBELIUS EXPERIMENT

The SIBELIUS experiment was designed to obtain information on the compatibility between beryllium and ceramics, as well as beryllium and steel, in a neutron environment. This experiment comprised irradiation of eight capsules, seven of which were independently purged with a He/0.1% H-2 gas mixture. Four capsules were used to examine beryllium/ceramic (Li2O, LiAlO2, Li4SiO4, and Li2ZrO3) and beryllium/steel (Types 316L and 1.4914) compacts. Isothermal anneal experiments have been run on representative beryllium and ceramic disks from each of the four capsules at 550 to 850 degrees C in steps of 100 degrees C. The results indicate that tritium release from the beryllium did not exhibit burst release behavior, as previously reported, but rather a progressive release with increasing temperature. Generally, similar to 99% of the tritium was released by 850 degrees C. Tritium release from the ceramic discs was quite similar to the behavior shown in other dynamic tritium release experiments an lithium ceramics. The tritium content in beryllium discs adjacent to a steel sample was found to be significantly lower than that found in a beryllium disc adjacent to a ceramic sample. Recoil of tritium from the ceramic into the beryllium appears to be the source of tritium entering the beryllium, probably residing in the beryllium oxide layer.