Development of laser decontamination(5); Decontanination test of the hot samples

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

Process of laser decontamination system is as follows. As the material is irradiated by laser beam, its surface is instantaneously heated and ablated. Laser decontamination system is able to decontaminate thoroughly. In this work, the characteristics of laser beam transmission by optical fibers, and decontamination effect of laser beam irradiation to test pieces which are cut down of pipe in the hot facility, are experimented for apply laser decontamination technique to radioactive wastes treatment and decommissioning of nuclear fuel facilities. The results are as follows. (1)Beam transmission. Transmission of Q switch pulse YAG laser's beam by optical fibers are examined. Transmission energy is in proportion to incident energy to fiber. Transmission energy of bundled fiber is 168mJ to 406mJ of incident energy. In the case of incident energy was 425mJ, transmission energy was decrease, because some fibers of bundled fiber were damaged by laser beam. (2)Decontamination test of the hot samples. Counting rate of pipe test piece were decreased more than 90% by first irradiation of Q switch pulse YAG laser. Counting rate of pipe test piece were decreased no more than 4% by on and after second irradiation of Q switch pulse YAG laser. To move the test piece slowly, and to raise the density of irradiation energy, and to use the helium gas for auxiliary gas are effective to increase decontamination effect.