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Journal Articles

Effect of liquid-sheet thickness on detection sensitivity for laser-induced breakdown spectroscopy of aqueous solution

Oba, Hironori; Saeki, Morihisa; Wakaida, Ikuo; Tanabe, Rie*; Ito, Yoshiro*

Optics Express (Internet), 22(20), p.24478 - 24490, 2014/10

https://doi.org/10.1364/OE.22.024478

Times Cited Count：17 Percentile：66.22(Optics)

For aqueous-solution-based elemental analysis, we used a thin liquid sheet (m-scale thickness) in laser-induced breakdown spectroscopy with nanosecond laser pulses. Laser-induced plasma is emitted by focusing a pulsed Nd:YAG laser (1064 nm) on a 5- to 80-m-thick liquid sheet in air. To optimize the conditions for detecting elements, we studied how the signal-to-background ratio (SBR) for H Balmer and Na-neutral emission lines depends on the liquid-sheet thickness. The SBR of the H Balmer and Na-neutral lines was maximized for a sheet thickness of 20 m at the laser energy of 100 mJ. The hydrodynamics of liquid flow induced by the laser pulse was analyzed by laser flash shadowgraph imaging. Time-resolved observation of the hydrodynamics and plasma emission suggests that the dependence of the SBR on the liquid-sheet thickness is correlated with the volume of flowing liquid that interacts with the laser pulses.

Oral presentation

Development of technology for inspecting the inside of the primary containment vessels and the reactor pressure vessels in the Fukushima Daiichi Nuclear Power Station

Ito, Chikara

no journal, ,

no abstracts in English

Oral presentation

Underwater analysis of (U,Zr)O $_{2}$ 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 $_{2}$ , 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 $_{2}$ , 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.

Oral presentation

Validation studies on quick and in-situ analysis of MOX fuel by combination of laser induced breakdown spectroscopy and ablation resonance absorption spectroscopy

Wakaida, Ikuo; Akaoka, Katsuaki; Miyabe, Masabumi; Kato, Masaaki; Otobe, Haruyoshi; Oba, Hironori; Khumaeni, A.

no journal, ,

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 $^{240}$ Pu/ $^{239}$ 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.

Oral presentation

Development of laser analysis for nuclear fuel management

Wakaida, Ikuo; Akaoka, Katsuaki; Miyabe, Masabumi; Khumaeni, A.; Oba, Hironori; Ito, Chikara

no journal, ,

In the new concept of next generation nuclear fuel cycle for long lived radioactive waste disposal by use of Accelerator Driven Subcritical reactor (ADS Cycle) and by a fast breeder reactor (FBR Cycle), utilization of low-decontaminated fuel with TRU will be promoted. Simultaneous analysis of element and isotope by the combination of Laser Induced Breakdown Spectroscopy (LIBS) and Ablation Resonance Absorption Spectroscopy was demonstrated by MOX fuel. 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, $^{240}$ Pu and $^{239}$ Pu have been observed separately, 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.

Oral presentation

Analysis and optimization of laser induced breakdown spectroscopy for nuclear material

Akaoka, Katsuaki; Miyabe, Masabumi; Otobe, Haruyoshi; Wakaida, Ikuo

no journal, ,

For the remote analysis of low DF TRU (Decontamination Factor Transuranic) fuel, we applied laser induced breakdown spectroscopy (LIBS) to uranium oxide, which included a small amount of calcium oxide as a simulated sample of impurities, and the spectrum emitted from laser-breakdown plasma was examined. To improve analysis precision of the ablated elements, we measured breakdown spectrum of Ca and U under the various experimental conditions such as laser power, observation delay time and gas pressure, optimized them, and obtained 5mJ, 5s and 2kPa. The spectrum was deconvoluted into each peak of some spectra component on U and Nd. And the result, actual intensity of Nd component intermingled in U was determined quantitatively. In order to evaluate the linearity in the impurity analysis, the experiments with various concentration of Nd were carried out.

Oral presentation

Underwater analysis of simulated corium debris using laser-induced breakdown spectroscopy

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 $_{2}$ , by the transportable fiber-coupled LIBS instrument. The experiments were carried out using a wavelength region of 7301100 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.

Oral presentation

Quantitative analysis and LIBS spectra analysis using the least-squares method

Akaoka, Katsuaki; Oba, Masaki; Miyabe, Masabumi; Wakaida, Ikuo

no journal, ,

For quantitative analysis of the mixed oxide (MOX) fuel using Laser Induced Breakdown Spectroscopy (LIBS), great deal of analysis and identification of spectra are necessary. Therefore, we tried "the analysis of the LIBS spectrum by the least-squares method" as quantitative analysis without identification and analysis of the spectra. As a result, the calibration curves for quantitative analysis could be got without them.

Oral presentation

Development of quick and remote analysis for severe accident reactor, 1; Laser remote analysis under severe environment

Wakaida, Ikuo; Oba, Hironori; Akaoka, Katsuaki; Oba, Masaki; Ruas, A.; Saeki, Morihisa; Miyabe, Masabumi; Ikeda, Yuji*; Sakka, Tetsuo*

no journal, ,

no abstracts in English

Oral presentation

Development of quick and remote analysis for severe accident reactor, 2-4; Estimation of LIBS spectra using the least-square method

Akaoka, Katsuaki; Oba, Masaki; Miyabe, Masabumi; Wakaida, Ikuo

no journal, ,

For quantitative analysis of the fuel debris using Laser Induced Breakdown Spectroscopy (LIBS), the measurement of the spectrum data for combination of materials is necessary. Therefore, we tried the estimate of the unknown elemental combination mixture spectrum, using "the analysis of the LIBS spectrum by the least-squares method". As a result, estimated spectra accorded with an actual spectra well.

Oral presentation