LASER ABLATION | DECONTAMINATION & DECOMMISSIONING Other materials were also laser ablated. These were


contaminated lead objects from various locations around the country, all with Alpha contamination (specifically radium). Lead sheets, lead bricks, lead “pigs” and even lead- lined gloves were decontaminated to 100% effectiveness in seconds with only one or two passes under the laser beam. During these tests, continuous air found no detectable


radiological airborne contaminants or the migration of contaminants to personnel or the laser equipment. Pre- and post-testing of the contaminated surfaces


revealed 100% efficiency in removing Alpha contamination and a significant reduction in Beta particles. Areas with denser Beta particles deeply imbedded into the base metal were not as easily removed by the laser, which does not damage the surface. Ultimately, the laser’s greatest success came from its


overall efficiency and a 93%-time savings compared to the manual grinding method. It is not surprising the technicians loved using the laser process compared to hours of stressful grinding.


The laser vaporises organic coatings, rust or oxides


Equipment decontamination In a recent study by Hi Tech Solutions and Reactor Services Inc, radiological decontamination using laser ablation was carefully tested over several weeks. The applications consisted of an aluminium intermodal container lid, a painted and raw steel intermodal container and a steam turbine flexure housing section, all with fixed contamination. The surface of each component was surveyed and


marked-off to identify the contaminated areas to measure the contamination levels pre- and post-laser ablation. The aluminium intermodal container lid had already been chemically decontaminated. Following that, and two days of power tool grinding, it retained fixed contamination that could not be removed. After a sweep of the laser beam, the beta particle


concentration was reduced by an average of 79%. Fixed alpha contamination up to 119 counts per minute (cpm) was removed from each contaminated area in less than a minute, allowing to free release. Contamination that could not be removed with


conventional cleaning and grinding was removed from the lid by laser ablation in less than 1 hour. Alpha and beta particle reduction was measured after


each pass of the scanned laser beam. The alpha particle measurements taken from the painted and bare steel intermodal container were on average 91% lower following one sweep of the laser beam. In each case, a secondary pass of the beam eliminated nearly all detectable levels of contamination.


Laser ablation decontamination Adapt Laser has worked with partners including CleanLASER to develop its laser systems. The portable cleanDECONT CL1000 and CL2000 laser ablation systems use an Nd:YAG, high power laser source. During operation, the laser source is protected by placing it in a clean location outside the radiologically controlled area. In the process, a hand-held, or robot mounted laser


optic, is used to move an intense, focused and pulsed laser beam across the target surface. The end effector and fiber optic umbilical, up to 100m away, are wrapped to remain clean and avoid contamination.


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and hydrocarbons — which normally contain fixed, non- smearable, radiological contaminants. Vaporised residues are collected immediately after ablation by a strong point- source vacuum system that captures process residues. They pass through multi-stage filtering to be scrubbed free of particles and vapours, preventing hazardous airborne contaminants and minimising clean-up. Laser surface preparation by mobile robot delivery is another option. Recent system improvements and new functionality,


includes: ● Laser ablation integrated with Laser Induced Breakdown Spectroscopy, a process control to analyse the target surfaces before and immediately after laser cleaning to verify the absence of unwanted residues.


● Simple means for end users to decouple and exchange fiber optic cables .


● Nuclear-rated glovebox to safely decontaminate small parts.


● Gantry-based robotic work cells to treat large parts inside a Class 1 Laser Safety enclosure.


Laser ablation decontamination will become more capable in future through automation, robotics and AI. ■


Below: Automated laser ablation system DECON in use Courtesy: J-tech, Ltd., Japan


Above: Pre- and post- alpha beta particles Measured on Contaminated Lead Surfaces Courtesy: Philotechnics, Ltd.


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