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Saeki, Morihisa; Iwanade, Akio; Ito, Chikara; Wakaida, Ikuo; Thornton, B.*; Sakka, Tetsuo*; Oba, Hironori
Journal of Nuclear Science and Technology, 51(7-8), p.930 - 938, 2014/07
Times Cited Count：70 Percentile：98.67(Nuclear Science & Technology)To inspect post-accident nuclear core reactor of the TEPCO Fukushima Daiichi Nuclear Power Plant, a transportable fiber-coupled LIBS instrument was developed. The developed LIBS instrument was designed to analyze the underwater sample in high-radiation field by single-pulse breakdown with gas flow or double-pulse breakdown. To check the feasibility of the assembled fiber-coupled LIBS instrument to the inspection inside Fukushima Daiichi Nuclear Power Plant, we investigated (1) influence of radiation dose on optical transmittance of the laser delivery fiber, (2) survey of the LIBS techniques to analyze the underwater sample and (3) candidates of emission lines for analysis of the debris. By employing the selected emission lines, we demonstrated that the developed LIBS instrument can analyze the simulated debris underwater by the single-pulse breakdown with the gas flow with high signal to noise ratio.
Toshimitsu, Masaaki; Saeki, Morihisa; Sugiyama, Akira; Oba, Hironori; Thornton, B.*; Sakka, Tetsuo*
no journal, ,
no abstracts in English
Toshimitsu, Masaaki; Saeki, Morihisa; Oba, Hironori; Thornton, B.*; Sakka, Tetsuo*
no journal, ,
A laser-induced breakdown spectroscopy (LIBS) technique for element analysis of samples submerged in water using a fiber optic light delivery set-up has been developed. The set-up delivers air to the sample surface via a tube and uses the same fiber optic for laser light delivery, and for observation of the light emitted by the micro-plasma generated for analysis. The emission spectra from metals, alloys and oxide samples such as Fe, SUS304, zircaloy-2, ZrO
can be clearly observed at wavelengths ranging from 730 nm to 870 nm.
Saeki, Morihisa; Iwanade, Akio; Ito, Chikara; Wakaida, Ikuo; Thornton, B.*; Sakka, Tetsuo*; Oba, Hironori
no journal, ,
To perform elemental analysis of solid samples under water and radiation field, we designed and constructed the instrument for fiber-coupled laser induced breakdown spectroscopy (LIBS). The LIBS analysis of the underwater sample is difficult, because the water quickly quenches the plasma plume that is generated by the ablation. To solve this problem, we prepared quasi-atmospheric condition around the plasma plume by using gas flow or double pulse irradiation system, and succeeded to observe similar spectrum between atmospheric and underwater condition. Moreover, the optical property of the fiber was investigated by exposing 
Co 
-ray with total dose over 1 MGy to the optic fiber. As a result, we found that radiation exposure to the fiber leads to slight damage in near infrared one. Thus, we designed the fiber-coupled LIBS system to perform laser ablation by near-infrared laser beam (1064 nm) and to efficiently detect plasma emission in near infrared region.
Saeki, Morihisa; Iwanade, Akio; Ito, Chikara; Wakaida, Ikuo; Thornton, B.*; Sakka, Tetsuo*; Oba, Hironori
no journal, ,
no abstracts in English
Oba, Hironori; Saeki, Morihisa; Miyabe, Masabumi; Akaoka, Katsuaki; Wakaida, Ikuo; Iwanade, Akio; Ito, Chikara; Tanabe, Rie*; Ito, Yoshiro*; Sakka, Tetsuo*; et al.
no journal, ,
no abstracts in English
Oba, Hironori; Saeki, Morihisa; Iwanade, Akio; Wakaida, Ikuo; Ito, Chikara; Sugiyama, Akira; Sakka, Tetsuo*; Thornton, B.*
no journal, ,
no abstracts in English
using laser-induced breakdown spectroscopy (LIBS)Oba, Hironori; Saeki, Morihisa; Ito, Chikara; Takano, Masahide; Akaoka, Katsuaki; Thornton, B.*; Sakka, Tetsuo*; Wakaida, Ikuo
no journal, ,
In the post-accident nuclear core reactor of the TEPCO Fukushima Daiichi Nuclear Power Plants, melted fuel core, fuel cladding and construction material (corium debris) might drop in the lower part of the reactor, which filled with seawater that was injected for urgent cooling. The major components of the debris material are assumed to be uranium oxide (UO, fuel core), zirconium alloy (Zry, fuel cladding) and iron (Fe, construction material). In this presentation, we report underwater analysis of simulated corium debris, (U,Zr)O, by the transportable fiber-coupled LIBS instrument. The experiments were carried out using a wavelength region of 730-1100 nm for pulsed-lasers and plasma emission measurements, which shows no attenuation in the optical transmittance of the fiber optic cable by intense radiation dose. Based on the observed emission spectrum in the region of 750-870 nm, we determined candidates of the emission lines of Zr, U and Fe that are applicable to analyses of the debris without mutual interference. The LIBS spectra of five different concentration ratio samples for Zr/U were measured to obtain calibration data. We succeeded to obtain linear calibration data for emission intensity ratio versus concentration ratio of Zr/U.
Saeki, Morihisa; Ito, Chikara; Wakaida, Ikuo; Thornton, B.*; Sakka, Tetsuo*; Oba, Hironori
no journal, ,
Oba, Hironori; Saeki, Morihisa; Ito, Chikara; Takano, Masahide; Akaoka, Katsuaki; Wakaida, Ikuo; Sakka, Tetsuo*; Thornton, B.*
no journal, ,
In order to inspect the post-accident nuclear core reactor of the TEPCO Fukushima Daiichi Nuclear Power Plants, a transportable fiber-coupled laser-induced breakdown spectroscopy (LIBS) instrument has been developed. In this presentation, we report underwater analysis of simulated corium debris, (U,Zr)O, by the transportable fiber-coupled LIBS instrument. The experiments were carried out using a wavelength region of 730
1100 nm for pulsed-lasers and plasma emission measurements, which shows no attenuation in the optical transmittance of the fiber optic cable by intense radiation dose. Based on the observed emission spectrum in the region of 750870 nm, we determined candidates of the emission lines of Zr, U and Fe that are applicable to analyses of the debris without mutual interference.
Oba, Hironori; Saeki, Morihisa; Ito, Chikara; Takano, Masahide; Akaoka, Katsuaki; Thornton, B.*; Sakka, Tetsuo*; Wakaida, Ikuo
no journal, ,
To inspect the post-accident nuclear core reactor of the TEPCO Fukushima Daiichi Nuclear Power Plants, a transportable fiber-coupled laser-induced breakdown spectroscopy (LIBS) instrument has been employed. In the post-accident nuclear core reactor, melted fuel core, fuel cladding and construction material might drop in the lower part of the reactor, which filled with seawater that was injected for urgent cooling. The major components of the debris material are assumed to be uranium oxide (UO, fuel core), zirconium alloy (Zry, fuel cladding), stainless steel (Fe, construction material) and boron carbide (B
C, critical control material). In this presentation, we report underwater analysis of simulated corium debris, (U,Zr)O, and BC by fiber-coupled LIBS instrument. The experiments were carried out using near-infrared wavelength region for pulsed-lasers and plasma emission measurements, which shows no attenuation in the optical transmittance of the fiber optic cable by intense radiation dose. We determined candidates of the emission lines of Zr, U, Fe and B (BO) that are applicable to analyses of the debris without mutual interference.
Oba, Hironori; Saeki, Morihisa; Wakaida, Ikuo; Thornton, B.*; Sakka, Tetsuo*
no journal, ,
A fiber-optic probe LIBS technique has been performed for analyzing elemental composition of samples under severe environment such as a high radiation dose condition. Application possibility of remote, onsite/in-situ LIBS as a tool for decommissioning of nuclear power station is discussed.
