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Abe, Tetsuo*; Onishi, Kazunori*; Takahashi, Yoshihiro*; Hirao, Toshio
Proceedings of the 6th International Workshop on Radiation Effects on Semiconductor Devices for Space Application (RASEDA-6), p.157 - 160, 2004/10
no abstracts in English
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JNC TJ6420 2000-002, 59 Pages, 2000/03
JNC-TJ6420-2000-002.pdf:4.54MB
no abstracts in English
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PNC TJ9602 97-001, 19 Pages, 1997/03
Failure of machine and structure has to be prohibited to avoid the leak of liquid natrium. The technology of detection of pre-existing phenomena before final failure becomes very important. In this basic study, the laser based ultrasonic sensor technique which is one of promising methods was invernstigated to summarize its principle and current status and to know the applicability of this method. Firstly the importance of non-destructive evaluation (NDE) method and the history of laser based NDE were reviewed. The technological basic of the non-contact generation of elastic wave by laser radiation and the non-contact defection of ultrasonic wave by laser interference technique. The difference of two modes of generation of elastic wave, that is, thermal stress mode and ablation mode, was reviewed. The detection methods of ultrasonic wave by laser interference such as homodyne interferometer, time-delay interferometer and confocal Fabry-Perot interferometer were investigated and their principle and characteristics were compared. Finally, examples of application of these methods for rough surface samples and high temperature materials were considered. It was concluded that these laser based NDE techniques were able to be used in practical applications.
Fukui, Yasutaka; ; Tanimoto, Kenichi; Terunuma, Seiichi
PNC TN9410 95-041, 171 Pages, 1994/12
As the material is irradiated by laser beam, its surface is instataneously heated and ablation. the contaminant in surface layer of radioactive wastes will be decontaminated, provided that such the physical phenomenon is used of decontamination technique. The applicability with decommissioning of laser decontamination technique are investigated by the research of the associated laser techniques and the removing test with metal surface. The results of the research and the test is as follows. (1)The research of laser decontamination. On the YAG and the eximer laser beam, there were some study reports of the decontamination, with the metal and the concrete. The structural material. the biological shield, and the waste strage vessel, these objects were regarded as the objects of the laser decontamination. (2)The removing test of the metal surfacc by lascr beam. The removing performance was examined by irradiating line forcused YAG laser beam with the stainless steel surface. The average removal depth rose, in proportion the product of the energy beam density and the number of beam pulse in He atomosphere. The removal depth was obtained more than 1
m, in condition of the laser beam energy was 400mJ and the moving velocity of the test piece was 0.25mm/sec. About 65% of the ablation products were collected, by the simple absorbing system of the open type. (3)Future plan. It is necessary, Examining the removing performance and the variable property of the removal surface, investigating the decontamination technique of the large area and the collecting technique of the ablation products, and so. Thereafter the application to the decontamination will be studied.