Development of laser decontamination technique (VI); Normal pulse laser decontamination test

Fukui, Yasutaka ; not registered; Kondo, Hitoshi; Tanimoto, Kenichi

By irradiating the material surface with the laser beam, it is possible that the surface is rapidly heated, melted and transpired. Laser decontamination technique which applies this process to the removal of the material surface layer contaminated in the radionuclide has been developed. In this report, factual waste laser decontamination experiment using the piping of the old Joyo Waste Treatment Facility was carried out for the purpose of applying laser decontamination technique to decommissioning of nuclear fuel cycle facility. And, secondary product splash prevention test of a normal pulse YAG laser was carried out. Main results are as follows. (1)Factual wast decontamination test It is necessary to decontaminate with the aim of 0.15mm removal depth in order to obtain the decontamination effect to B.G.level, when the pollution piping is decontaminated using a normal pulse YAG laser. Conditions for efficiently obtaining 0.15mm removal depth and l.3kJ/cm irradiation energy density in the irradiation of 2 times with 364W oscillator are 30Hz frequency, duty ratio 50 % in irradiation energy density 1.3kJ/cm, and test piece mobile speed 30mm/s. (2)The splash prevention of the secondary product test For the purpose of the splash prevention of the secondary product, the small hood for splash prevention installed in the decontamination nozzle was made. As a result of the test, the following were confirmed : That it does not scatter for the high position almost, though it horizontally scatters in the wide angle, and that the part of the secondary product scatters in the hood outside by reflecting in the hood. It is necessary to make the hood with wedged structure and attraction mechanism for the purpose of shatter-resistant of secandary products.