A Study on Sorption of Tritium on Some Metals

The adsorption and desorption behaviors of tritium on the surfaces of stainless steel, copper, molybdenum and Kovar were studied. After the exposure in tritium gas ( 9 kPa gaseous tritium, 2 minutes exposure at 873 K and 40 minutes cooling ), the tritium desorbed at room temperature and during heating up to 1123 K and total sorbed tritium of the samples were measured. The results showed that the desorbed tritium at room temperature was only 1∼6% of total sorbed tritium and its amount order was: Kovar >copper > stainless steel > molybdenum. The total desorbed tritium was ranging from 2 to 22 MBq/cm², the largest is for Kovar and the smallest is for stainless steel. The tritium released from these materials at room temperature and during heating was mostly in the form of HTO. The thermo-desorption spectra of these materials were obtained. It was found that at least 5, 3, 3, 4 sorption states of tritium exist in the exposed Kovar, molybdenum, copper and stainless steel samples respectively. Doping 1% hydrogen in the carrying gas of helium during the thermo-desorption had rather effect on this process.