Behavior of tritium release from thin boron films deposited on SS316

Release and diffusion behavior of tritium implanted into thin boron films were examined by isochronal and isothermal heating. For comparison, a polycrystal boron plate was also employed for the same examinations. Changes in the residual amount of tritium with heating were measured by β-ray-induced X-ray spectrometry (BIXS). Most of the tritium desorbed at room temperature was in HTO form, and the residual amount decreased to 20–30% of the initial amount loaded at 773 K. The time-course of the tritium reduction was well represented by an exponential function, suggesting that the tritium release obeys first order reaction kinetics and the rate-determining step is a diffusion process. The apparent activation energy of diffusion was determined to be 0.17 eV. Both the depth profiles calculated from a diffusion equation and determined by computer simulation of X-ray spectra agreed quite well for polycrystal boron.