Surface contamination of used tritium gas cylinder

At collection of contaminated wastes with tritium, it is required by regulation to know the amount of tritium trapped to the surface and in the bulk of disposal materials. However, it is difficult to measure the amount of tritium on the surface of materials such as tritium gas cylinder or pipes and reaction vessels in a tritium handling system. In this study, several experiments were performed applying the isotope exchange reaction between water vapor in the gas phase and tritium in the surface water to estimate the amount of tritium on the inner surface of used tritium gas cylinder made with aluminum alloy, and the results obtained from these experiments were compared with result of the smear method. Observed value for the amount of tritium on the surface of the aluminum alloy was similar to the value estimated using the trapping capacity of water on aluminum obtained by our previous experimental results. It is confirmed that injection of a little amount of water is possible to extract all tritium on the cylinder inner surface. The smear method could not give quantitatively reliable results for measuring the amount of tritium on the surface.