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Miyabe, Masabumi; Oba, Masaki; Jung, K.; Iimura, Hideki; Akaoka, Katsuaki; Kato, Masaaki; Otobe, Haruyoshi; Khumaeni, A.*; Wakaida, Ikuo
Spectrochimica Acta, Part B, 134, p.42 - 51, 2017/08
Times Cited Count：30 Percentile：91.13(Spectroscopy)Spectroscopic properties of atomic species of plutonium were investigated by combining laser ablation and resonance absorption techniques for the analysis of a plutonium oxide sample. For 17 transitions of Pu atoms and ions, the absorbance, isotope shift, and hyperfine splitting were determined via Voigt profile fitting of the recorded absorption spectra. Three transitions were selected as candidates for analytical use. Using these transitions, we investigated the analytical performance that was attainable and determined a correlation coefficient R2 between the absorbance and plutonium concentration of 0.9999, a limit of detection of 30-130 ppm, and a relative standard deviation of approximately 6% for an abundance of 
Pu of 2.4%. These results demonstrate that laser ablation absorption spectroscopy is applicable to the remote isotopic analysis of highly radioactive nuclear fuels and waste materials containing multiple actinide elements.
using laser-induced breakdown spectroscopy (LIBS)Oba, Hironori; Saeki, Morihisa; Ito, Chikara; Takano, Masahide; Akaoka, Katsuaki; Thornton, B.*; Sakka, Tetsuo*; Wakaida, Ikuo
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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.
Wakaida, Ikuo; Akaoka, Katsuaki; Miyabe, Masabumi; Khumaeni, A.; Oba, Hironori; Saeki, Morihisa; Ito, Chikara; Otobe, Haruyoshi; Kato, Masaaki
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In the next generation nuclear fuel cycle, low-decontaminated fuel with TRU will be strongly required, and convenience, quick analytical techniques will be necessary. Simultaneous analysis of element and isotope by the combination of Laser Induced Breakdown Spectroscopy (LIBS) and Ablation Resonance Absorption Spectroscopy was demonstrated. For elemental analysis, detection lower limit of 1000 ppm of Pu in U oxide and relative error under 5% have been obtained within 5 min. For isotope analysis, Pu and 
Pu have been observed completely separated, and detection lower limit of several 10 ppm and error under 1% have been accomplished. A simple antenna coupled microwave assisted LIBS was performed and the enhancement of emission intensity of several 10 times was demonstrated. For liquid sample, ultra-thin laminate flow as the laser focused target was accomplished high sensitivity of ppb. For in-situ monitoring, Optical Fiber LIBS Probe by radiation resistant optical fiber is under construction.
Wakaida, Ikuo; Akaoka, Katsuaki; Miyabe, Masabumi; Kato, Masaaki; Otobe, Haruyoshi; Oba, Hironori; Khumaeni, A.
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In Japan Atomic Energy Agency (JAEA), research and development of quick analysis for next-generation MOX fuel without chemical analysis and neutron measurement had been carried out as the entrusted project by MEXT, and basic performances by using un-irradiated MOX fuel were demonstrated. In elemental analysis by Laser Induced Breakdown Spectroscopy (LIBS) with high resolution spectrometer, relative error of 2.9% at 30% Pu and the detection lower limit of 2,500 ppm in U oxide were demonstrated with the operation time of 5 min.. In isotope ratio analysis by Ablation Resonance Absorption Spectroscopy, tunable semiconductor laser system was constructed, and the relative deviation less than 1% in the ratio of Pu/Pu and sensitivity of 30-100 ppm in U were also accomplished within 5min. operation. As for an analysis in liquid sample, ultra-thin laminate flow was experimented as LIBS target, and the sensitivity comparable to conventional ICP-AES was confirmed.
Oba, Hironori; Saeki, Morihisa; Akaoka, Katsuaki; Wakaida, Ikuo
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Wakaida, Ikuo
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Wakaida, Ikuo; Akaoka, Katsuaki; Oba, Masaki; Oba, Hironori; Tamura, Koji; Saeki, Morihisa; Matsumoto, Ayumu*; Sakka, Tetsuo*; Ikeda, Yuji*; Taira, Takunori*
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Wakaida, Ikuo; Miyabe, Masabumi; Akaoka, Katsuaki; Oba, Hironori; Taira, Takunori*
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no abstracts in English
Miyabe, Masabumi; Oba, Masaki; Akaoka, Katsuaki; Kato, Masaaki*; Wakaida, Ikuo
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In the decommissioning of Fukushima Daiichi Nuclear Power Plant, it is expected that extremely strong radioactive waste will be generated, including various alpha-radionuclides and fission products. In particular, since the alpha-radionuclides have many isobars, it is difficult to apply conventional mass spectrometry or radioanalytical technique for the analysis of its isotopic composition. For such analysis, we are developing a remote rapid analytical technique using laser ablation resonance spectroscopy. Thus far laser resonance spectroscopy of elements and isotopes important for atomic energy fields including uranium and plutonium has been carried, so it was demonstrated that resonance features of heavy elements are identified separately. Further, the linearity of the resonance signal is found to be good in the wide range from the detection limit of about 100 ppm to several 10 percent. It was also found that the spectroscopy to suppress Doppler broadening is required for light elements such as fission products having smaller isotope shifts. We also discuss the current state of development of high resolution spectroscopy using Doppler-free spectroscopic techniques.
Miyabe, Masabumi; Oba, Masaki; Akaoka, Katsuaki; Wakaida, Ikuo
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In the decommissioning of the Fukushima Daiichi Nuclear Power Plant, remote elemental and isotopic analysis of highly radioactive substances containing actinide elements, fission products, and reactor materials is of great importance. The composition information is required for various purposes such as verification of safeguards, prevention of recriticality accident, and planning of waste treatment procedure. However, in radiochemical analysis, owing to its limited energy resolution it is very difficult to identify individual nuclides of U and Pu, and because there are various isobars produced through radiative decay chain, isotopic analysis with mass spectrometry is also difficult. Thus we are developing a remote isotopic analytical technique combining atomic absorption spectroscopy and laser ablation technique. Various experimental conditions were optimized to realize highly sensitive and isotope selective analysis. Also, in order to reduce the Doppler effect and the Stark effect, we investigated the expansion behavior of the ablation plume to clarify underlying physics. Moreover, the analytical performance was evaluated using a mixture oxide samples of uranium and plutonium, and good performances were obtained. Furthermore, in order to apply this method to the analysis of nano-particles generated with laser cutting etc., we studied the method of decomposing nano-particles into atoms. We would like to report on the current status and future prospects of the development of this new analytical technique.
Wakaida, Ikuo; Oba, Hironori; Miyabe, Masabumi; Akaoka, Katsuaki; Oba, Masaki; Tamura, Koji; Saeki, Morihisa; Nakanishi, Ryuzo; Ikeda, Yuji*; Sakka, Tetsuo*; et al.
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Wakaida, Ikuo; Oba, Hironori; Miyabe, Masabumi; Akaoka, Katsuaki; Oba, Masaki; Tamura, Koji; Saeki, Morihisa; Nakanishi, Ryuzo; Ikeda, Yuji*; Sakka, Tetsuo*; et al.
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Miyabe, Masabumi; Yamada, Tomonori; Shibata, Takuya; Ito, Chikara; Daido, Hiroyuki; Hasegawa, Shuichi*
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Application of laser ablation is studied in various fields such as laser processing, material science, and analysis. Even in the decommissioning of Fukushima, it is desired to use laser-induced breakdown spectroscopy (LIBS), detecting light emission from laser plasma for remote analysis of decommissioning-related substances such as fuel debris having high radioactivity. However, information on isotopic composition as well as elemental composition is often needed for nuclear engineering field, and there is a technical problem that sufficient isotopic resolution cannot be obtained with LIBS. So far, we have developed an analytical technique in which generated laser plasma is cooled in a low-pressure rare gas and is interacted with a tunable laser beam, and demonstrated that sufficient spectroscopic resolution can be obtained from the resultant absorption spectra. However, even with this method, the narrowest linewidth of the spectra is around several GHz due to Doppler broadening originated from the motion of atoms at room temperature, so remote isotopic analysis was difficult for nuclides having smaller isotope shifts. In this study, we have demonstrated high-resolution spectroscopic measurement by irradiating counter-propagating two resonance laser beams to a laser plasma and measuring laser-induced fluorescence from the highly excited atoms generated through two-step resonance excitation scheme. The present results clearly show the possibility of remote isotopic analysis even for isotopes having smaller isotope shifts.
Wakaida, Ikuo; Oba, Hironori; Taira, Takunori*; Ikeda, Yuji*
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Wakaida, Ikuo
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Wakaida, Ikuo; Oba, Hironori; Akaoka, Katsuaki; Shibata, Takuya; Nakanishi, Ryuzo; Karino, Takahiro; Sakamoto, Kan*; Ikeda, Yuji*; Taira, Takunori*
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Oba, Hironori; Akaoka, Katsuaki; Wakaida, Ikuo
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Oba, Hironori; Akaoka, Katsuaki; Karino, Takahiro; Wakaida, Ikuo; Tamura, Koji*; Nakanishi, Ryuzo*; Sakamoto, Kan*; Taira, Takunori*
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Development of remote inspection and elemental analysis methods in a harsh radiation environment is required, such as inspection of the nuclear fuel debris at the bottom of the post-accident nuclear reactor (Tokyo Electric Power Company, Fukushima Daiichi Nuclear Power Plant). Laser-induced breakdown spectroscopy (LIBS) has been utilized as an effective qualitative and quantitative analytical method for elemental analysis. Inspecting the damaged reactor vessels requires a longer fiber-optic (FO) cable, which significantly attenuates the delivered laser energy by absorption and scattering in the fiber. We report on the first trial of our FO-LIBS system using the microchip laser (MCL) to identify and quantify elements in surrogate nuclear fuel debris under gamma irradiation, the results of trials on surrogate debris analysis, containing uranium oxide, using the MCL, and the results of 100 m-long fiber-delivered LIBS.
Oba, Hironori; Akaoka, Katsuaki; Karino, Takahiro; Wakaida, Ikuo; Ouchi, Atsushi*; Miura, Yusuke*; Eto, Yoshinori*; Sakamoto, Kan*
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