Study of laser assisted decontamination of commonly used clad surfaces

The decontamination factor, defined as the ratio of initial to residual activity, is studied as a function of laser fluence for three kinds of clad surfaces viz., plain zircaloy, autoclaved zircaloy, and stainless steel with cesium as the simulated contamination. It has been found that the decontamination factor exhibits a maximal behavior with the laser fluence and its maximum value occurs at different laser fluences in the three cases. The maximal behavior is attributed to reduced coupling of energy from the laser beam to the substrate due to the initiation of surface-assisted optical breakdown. The results obtained in the experiment carried out in helium environment qualitatively support this explanation.