A Q-switched Nd:YAG laser with a 1,064 nm and 450 mJ/pulse was employed to study the cleaning characteristics of Type 304 stainless steel specimens artificially contaminated with Cs+ ions. Before laser irradiation, the specimens were treated with KCl and KNO3, respectively. The relative atomic molar percent of Cs+ ion on a metal surface was analyzed by EPMA. Before and after the laser irradiation, the morphology of the metal surfaces was investigated by SEM. The optimum laser fluence determined in the experimental range was 57.3 J/cm2. For all the test specimens, more than 95% of the Cs+ ions were removed by the application of 40 laser shots at 57.3 J/cm2. Cs+ ion removal efficiency was improved by the addition of nitrate ions to the contaminated metal surface. Surface temperature during the laser irradiation was calculated using Hertz-Knudsen equation to investigate the surface characteristics. A portion of particulates generated during the laser irradiation was found to accumulate around a crater of the specimen treated with the KCl solution. It was concluded that the ablated Cs+ ions formed an oxide after thermal activation on the surface and deposited on a metal surface for the KCl system. The higher Cs+ ion removal efficiency of the KNO3 system was attributed to the decomposition of the nitrate ions at a relatively low temperature and the easy reaction of the Cs+ ions with the oxygen generated from the decomposition of nitrate ions.

Laser Cleaning Cs+ Nitrate Chlorine Hertz-Knudsen

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