Abstract: A method for the removal of embedded contamination from a metallic surface in which a laser beam is directed on to the contaminated surface. The laser beam has sufficient power density to cause direct ejection of laser-generated melt pool liquid from the metallic surface thereby removing a metallic surface layer containing the embedded contamination. Means are provided for the collection of laser ejected material in order to prevent recontamination of the metallic surface or contamination of previously uncontaminated surfaces.

Abstract: In a method of detecting the spatial position of a laser beam relative to a body locatable in the path of the laser beam by detecting an acoustic signal produced by the beam in the body, wherein the laser beam carries a power modulation signal and the body has a plurality of acoustic sensors for detecting the acoustic signal produced in the body by the laser beam, the method includes detecting in the outputs of the acoustic sensors signals corresponding to the power modulation of the incident laser beam and detecting any difference in phase between the detected signals. A processor may be provided for processing the outputs of the acoustic sensors, the processor including a sensor for sensing in the respective outputs signals corresponding to the power modulation of the output beam of the laser and a phase sensitive detector for detecting differences in phase between the detected signals.

Abstract: A method of treating a concrete or other non-metallic surface contaminated with embedded radionuclides to reduce the total level of radioactivity in a concrete or other hydraulically bonded material body is described. The method comprises the steps of producing relative mutual movement between the surface to be removed and a laser heat source such that a layer adjacent the surface is caused to be detached from said concrete body. The surface may be detached as a vapour, in flakes or as a sheet.

Abstract: In a method of treating a surface 12 of an object 10 contaminated with radionuclides 14, a laser source 16 is directed at the surface 12 to apply a local area 18 of intense heat to the surface 12. The laser source 16 is arranged to pass in a raster manner to cause local melting of the surface 12, surface 12 subsequently solidifying and fixing the radionuclides 14 therein. At least one layer of a coating material be applied before or after the application of the intense heat to fix and seal the radionuclides on or in the object.