Measurement of plutonium spectrum using laser induced breakdown spectroscopy; High resolution spectroscopy (350-670nm)

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

JAEA-Research 2020-001, 142 Pages, 2020/03

JAEA-Research-2020-001.pdf:4.0MB

Laser Induced Breakdown Spectroscopy (LIBS) method is an attractive technique because real-time, in-situ and remote elemental analysis is possible without any sample preparation. The LIBS technique can be applied for analyzing elemental composition of samples under severe environments such as the estimation of impurities in the next generation nuclear fuel material containing minor actinide (MA) and the detection of fuel debris in the post-accident nuclear core reactor of TEPCO's Fukushima Daiichi Nuclear Power Station. For applying LIBS to the analysis of nuclear fuel materials, it is indispensable to identify the emission spectrum and its intensity on impurities intermingled within complex emission spectra of matrix elements such as uranium (U) and plutonium (Pu). In the present study, an echelle spectrometer with a resolving power of 50,000 was employed to identify spectra of plutonium of wavelength ranging from 350 to 670nm. The 465 atomic spectra and 341 ionic spectra can be identified. We have confirmed that the measured wavelength of spectra is consistent with published values.

Preliminary missions for the decommissioning of the laboratory building No.1 for the plutonium research program

Segawa, Yukari; Horita, Takuma; Kitatsuji, Yoshihiro; Kumagai, Yuta; Aoyagi, Noboru; Nakada, Masami; Otobe, Haruyoshi; Tamura, Yukito*; Okamoto, Hisato; Otomo, Takashi; et al.

JAEA-Technology 2016-039, 64 Pages, 2017/03

JAEA-Technology-2016-039.pdf:5.24MB

The laboratory building No.1 for the plutonium research program (Bldg. Pu1) was chosen as one of the facilities to decommission by Japan Atomic Energy Agency Reform in September, 2013. The research groups, users of Bldg. Pu1, were driven by necessity to remove used equipment and transport nuclear fuel to other facilities from Bldg. Pu1. Research Group for Radiochemistry proactively established the Used Equipment Removal Team for the smooth operation of the removal in April, 2015. The team classified six types of work into the nature of the operation, removal of used equipment, disposal of chemicals, stabilization of mercury, stabilization of nuclear fuel, transportation of nuclear fuel and radioisotope, and survey of contamination status inside the glove boxes. These works were completed in December, 2015. This report circumstantially shows six works process, with the exception of the approval of the changes on the usage of nuclear fuel in Bldg. Pu1 to help prospective decommission.

Measurement of uranium spectrum using laser induced breakdown spectroscopy; High resolution spectroscopy (470-670 nm)

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

JAEA-Research 2016-005, 40 Pages, 2016/05

JAEA-Research-2016-005.pdf:1.82MB

Laser Induced Breakdown Spectroscopy (LIBS) method is an attractive technique because real-time, in-situ and remote elemental analysis is possible without any sample preparation. The LIBS technique can be applied for analyzing elemental composition of samples under severe environments such as the estimation of impurities in the next generation nuclear fuel material containing minor actinide (MA) and the detection of fuel debris in the post-accident nuclear core reactor of TEPCO Fukushima Daiichi Nuclear Power Plant. For applying LIBS to the analysis of nuclear fuel materials, it is indispensable to identify the emission spectrum and its intensity on impurities intermingled within complex emission spectra of matrix elements such as uranium (U) and plutonium (Pu). In the present study, an echelle spectrometer with a resolving power of 50,000 was employed to identify spectra of natural uranium of wavelength ranging from 470 to 670 nm. The 173 atomic spectra and 119 ionic spectra can be identified. We have confirmed that the measured wavelength and oscillator strength of spectra are consistent with published values.

Laser-induced breakdown spectroscopy for nuclear fuel material

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

Reza Kenkyu, 42(12), p.918 - 922, 2014/12

For the remote analysis of the next generation nuclear fuel material containing minor actinide (MA), Laser Induced Breakdown Spectroscopy (LIBS) was applied to uranium oxide (UO) including a small amount of neodymium oxide (NdO) as a simulated sample of MA. By using deconvolution technique for the spectra of Nd in U, the complex, overlapped and confused spectra were separated and their actual intensities were determined. As a result, the calibration curve with good linearity and the detection limit of less than 700 ppm were demonstrated.

Propagation of U(V)-reduction in the presence of U(IV) aggregate in a weakly acidic solution

Kitatsuji, Yoshihiro; Otobe, Haruyoshi; Kimura, Takaumi; Kihara, Sorin*

Electrochimica Acta, 141, p.6 - 12, 2014/09

https://doi.org/10.1016/j.electacta.2014.07.012

Reduction processes of U(VI) in weakly acidic solutions were investigated based on electrochemical and spectrophotometric measurements. A reversible one-electron reduction of U(VI) to U(V) and a further irreversible reduction of U(V) were observed voltammetrically at a gold microdisk electrode in solutions of pH from 2.0 to 3.5. Aggregates of U(IV) were formed as a deposit on the electrode and a colloid in the bulk solution, when the electrolysis was carried out at a gold gauze electrode, even though the potential applied was that available for the first one-electron reduction wave of U(VI) observed. It was elucidated that the aggregate was produced by the combination of the one-electron reduction to U(V) and the disproportionation of U(V) producing U(IV) and U(VI). The aggregate enhanced the rate of the disproportionation of U(V), and hence the reduction current of U(VI) increased abruptly when a definite amount of aggregate was formed on the electrode, in the solution, or both.

Syntheses and thermal analyses of curium trichloride

Hayashi, Hirokazu; Takano, Masahide; Otobe, Haruyoshi; Koyama, Tadafumi*

Journal of Radioanalytical and Nuclear Chemistry, 297(1), p.139 - 144, 2013/07

https://doi.org/10.1007/s10967-012-2413-7

Curium trichloride was synthesized by the solid state reaction of curium nitride with cadmium chloride heated from room temperature to 748K in a dynamic vacuum. The product was hexagonal CmCl, of which lattice parameters were determined to be a= 0.73850.0005 and c= 0.42010.0005 nm. The melting temperature of the CmCl sample was determined to be 9703 K by differential thermal analyses using a gold crucible. These values are close to those reported in literatures. The results show that mg-scale CmCl samples for thermochemical measurements were prepared from the purified oxide sample without the use of corrosive reagents.

Maintenance of Module for TRU High Temperature Chemistry

Tagami, Susumu; Sano, Naruto; Otobe, Haruyoshi; Akabori, Mitsuo; Kurobane, Shiro

JAEA-Technology 2010-034, 65 Pages, 2010/10

JAEA-Technology-2010-034.pdf:3.56MB

An experimental facility called the Module for TRU High Temperature Chemistry (TRU-HITEC) was installed in the Back-end Cycle Key Elements Research Facility (BECKY) of the Nuclear Fuel Cycle Safety Engineering Research Facility (NUCEF) in February, 2003. The main purpose of this facility is to perform the basic studies of the behavior the transuranium elements (TRU) in pyrochemical reprocessing and oxide fuels. Hot-experiment started in December, 2004. TRU-HITEC consists of three / cells and a glove box. This is the only facility in the country as large-scale facilities maintained a high purity argon gas atmosphere. The experience gained through the maintenance and improvement is useful also for the maintenance of similar designed facility. This report describes the maintenance method and improvement for the purpose of keeping the performance of TRU-HITEC.

Laser induced breakdown spectroscopy of the uranium including calcium; Time resolved measurement spectroscopic analysis (Contract research)

Akaoka, Katsuaki; Maruyama, Yoichiro; Oba, Masaki; Miyabe, Masabumi; Otobe, Haruyoshi; Wakaida, Ikuo

JAEA-Research 2010-004, 13 Pages, 2010/05

JAEA-Research-2010-004.pdf:1.42MB

For the remote analysis of low DF TRU (Decontamination Factor Transuranic) fuel, Laser Breakdown Spectroscopy (LIBS) was applied to uranium oxide including a small amount of calcium oxide. The characteristics, such as spectrum intensity and plasma excitation temperature, were measured using time-resolved spectroscopy. As a result, in order to obtain the stable intensity of calcium spectrum for the uranium spectrum, it was found out that the optimum observation delay time of spectrum is 4 microseconds or more after laser irradiation.

Basic study on remote analysis for next generation fuel by combination of laser induced breakdown spectroscopy (LIBS) and ablation initiated resonance absorption spectroscopy (AIRAS)

Wakaida, Ikuo; Akaoka, Katsuaki; Oba, Masaki; Maruyama, Yoichiro; Miyabe, Masabumi; Otobe, Haruyoshi; Niki, Hideaki*

Kaku Busshitsu Kanri Gakkai (INMM) Nippon Shibu Dai-30-Kai Nenji Taikai Rombunshu (CD-ROM), 9 Pages, 2010/01

In Japan Atomic Energy Agency, basic study on remote analysis by combination of LIBS for impurity measurement and AIRAS for isotope measurement is performed to apply rapid and on-site analysis of next generation fuel. For the impurity measurement of the sample with the matrix of Lanthanide or Uranium oxide which has complex spectrum structure, detection linearity to % order and the detection limit of order 100 ppm are obtained by the optimization of the measurement conditions of the delay time, gas pressure and by the deconvolution of the spectrum. For the isotope analysis, the laser system specialized for the resonance spectroscopy by frequency stabilized semiconductor tunable laser has been developed. And under the low pressure rare gas condition, spectrum resolution of 800 MHz is measured and the detection of U in Natural Uranium is realized.

Oxygen potential measurements of AmPuO by EMF method

Otobe, Haruyoshi; Akabori, Mitsuo; Arai, Yasuo

Journal of Nuclear Materials, 389(1), p.68 - 71, 2009/05

https://doi.org/10.1016/j.jnucmat.2009.01.009

The dependence of the oxygen potentials on oxygen non-stoichiometry and temperature of AmPuO has been elucidated by electromotive force (EMF) measurements. The value of AmPuO was changed at 1333 K over 0.02 0.25 by the coulomb titration method. The temperature dependence of the oxygen potential was also measured in the range of 1173-1333 K. It was found that the oxygen potential decreased from -80 to -360 kJmol with increasing from 0.021 to 0.22 at 1333 K and that those remained almost constant at -360 kJmol around = 0.23. It was concluded that AmPuO should be composed of the single fluorite-type phase over 0.02 0.22 and the mixed phases of fluorite-type and (Am,Pu)O around = 0.23.