Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Yomogida, Takumi; Saeki, Morihisa*; Morii, Shiori; Oba, Hironori*; Kitatsuji, Yoshihiro
Analytical Sciences, 37(12), p.1843 - 1846, 2021/12
Times Cited Count：0 Percentile：0(Chemistry, Analytical)In this study, we developed a simple and one-step Pd separation technique based on photoreduction with Xe lamp irradiation for the determination of 
Pd in highly radioactive samples. A simulated high-level radioactive liquid wastes (HLLW) solution, which consists of 14 major elements (Rb, Sr, Zr, Mo, Ru, Rh, Pd, Cs, Ba, La, Ce, Pr, Nd, Sm) in a 3 mol L
HNO
solution, was used to evaluate the separation performance. The Pd precipitate were formed by Xe lamp irradiation and recovered by centrifugation. The results showed that the recovery of Pd from a simulated HLLW solution depend on the irradiation time and concentration of ethanol. By optimizing the conditions at photo irradiation, the Pd recovery from the simulated HLLW solution reached up to 50 %, while 99.5 % of the other 13 elements were separated. The Pd precipitate could be separated from the elements that are the main source of radioactivity (Sr, Cs, and Ba) and the source of spectral interference for the determination of Pd (Zr, and Ru). These results indicate that selective separation of Pd is achieved with the proposed method, showing the applicability of the proposed separation technique to HLLW samples.
Saeki, Morihisa*; Matsumura, Daiju; Yomogida, Takumi; Taguchi, Tomitsugu*; Tsuji, Takuya; Saito, Hiroyuki*; Oba, Hironori*
Journal of Physical Chemistry C, 123(1), p.817 - 824, 2019/01
Times Cited Count：14 Percentile：53.94(Chemistry, Physical)Reaction kinetics of laser-induced particle formation in an aqueous solution of PdCl
was investigated by transmission electron microscope (TEM) and dispersive X-ray absorption fine structure (DXAFS). The Pd particle was generated by irradiation of nanosecond pulsed 266-nm laser. The TEM observation showed dependence of the particle size on the laser fluence and promotion of the particle growth by irradiation of high-fluence laser. The DXAFS data give us the Pd
concentration. Temporal changes of the Pd concentration analyzed based on Finke-Watzky two step mechanism. The analysis elucidates that the laser photon contributes to the reduction of the PdCl ion by the one-photon process and to the autocatalytic growth of the Pd particles by the multi-photon process.
Kusaka, Ryoji
Bunko Kenkyu, 67(6), p.239 - 240, 2018/12
A spectroscopic technique for analysis developed by collaboration between Japan Atomic Energy Agency (JAEA) and Quantum and Radiological Science and Technology (QST) is discussed for readers outside the field of nuclear energy. This paper introduces a quantitative analysis for Pd radioisotope contained in a spent nuclear fuel by using laser-induced photoreduction and inductively coupled plasma mass spectrometry (ICP-MS). The importance and problems of quantitative analysis for radioisotopes in spent nuclear fuels are described, and the principle, advantages, and future applications of the spectroscopic technique are discussed.
Pd by ICP-MS; The Relation between separation conditions and Pd recoveryYomogida, Takumi; Asai, Shiho; Saeki, Morihisa*; Hanzawa, Yukiko; Horita, Takuma; Esaka, Fumitaka; Oba, Hironori*; Kitatsuji, Yoshihiro
Bunseki Kagaku, 66(9), p.647 - 652, 2017/09
Times Cited Count：2 Percentile：6.93(Chemistry, Analytical)Palladium-107 is a long-lived fission product, which can be found in high-level radioactive liquid wastes (HLLW). Determination of the Pd contents in HLLW is essential to evaluate the long-term safety of HLLW repositories. However, the Pd content in HLLW has not been reported because of difficulties in pretreatment for the measurement. In this study, we investigated applicability of laser-induced photoreduction to HLLW solution: it enables a simple and non-contact separation of Pd. The results showed the recovery of 60% was achieved at the conditions: 40% ethanol, 20 min irradiation, 100 mJ of pulse energy. Additionally, major radionuclides and potentially interfering components in ICP-MS were removed from the simulated HLLW over a wide concentration range of Pd from 0.24 to 24 mg L, showing the applicability of the proposed separation technique to HLLW samples.
Saeki, Morihisa*; Taguchi, Tomitsugu*; Oba, Hironori*; Matsumura, Daiju; Tsuji, Takuya; Yomogida, Takumi
Denki Gakkai Kenkyukai Shiryo, Denshi Zairyo Kenkyukai (EFM-17-010
021), p.15 - 18, 2017/09
Irradiation of nanosecond pulsed UV laser into a solution of palladium ion leads to formation of palladium particles with sub-micron size particles by time-resolved X-ray absorption spectroscopy.
Pd in Pd recovered by laser-induced photoreduction with inductively coupled plasma mass spectrometryAsai, Shiho; Yomogida, Takumi; Saeki, Morihisa*; Oba, Hironori*; Hanzawa, Yukiko; Horita, Takuma; Kitatsuji, Yoshihiro
Analytical Chemistry, 88(24), p.12227 - 12233, 2016/12
Times Cited Count：16 Percentile：53.58(Chemistry, Analytical)Safety evaluation of a radioactive waste repository requires credible activity estimates confirmed by actual measurements. A long-lived radionuclide, Pd, which can be found in radioactive wastes, is one of the difficult-to-measure nuclides and results in a deficit in experimentally determined contents. In this study, a precipitation-based separation method has been developed for the determination of Pd with ICP-MS. The photoreduction induced by laser irradiation at 355 nm provides short-time and one-step recovery of Pd. The proposed method was verified by applying it to a spent nuclear fuel sample. In order to efficiently recover Pd, a natural Pd standard was employed as the Pd carrier. The chemical yield of Pd was about 90% with virtually no impurities, allowing accurate quantification of Pd.
Pd in Pd recovered from spent nuclear fuel solution by laser induced photoreductionAsai, Shiho; Yomogida, Takumi; Saeki, Morihisa*; Oba, Hironori*; Hanzawa, Yukiko; Horita, Takuma; Kitatsuji, Yoshihiro
no journal, ,
Pd is a long-lived radionuclide that can be found in HLW. The estimation of the amount of Pd in HLW is considered crucial for long-term safety evaluation of HLW. However, experimentally determined concentrations of Pd in HLW has not been reported due to the difficulty in recovering significant amount of Pd from HLW which has high radioactivity. In this study, we have focused on remotely operated separation technique based on laser-induced photoreduction, which allows to keep the distance from samples. To validate the applicability of the proposed method, spent nuclear fuel with a traceable irradiation history was employed instead of HLW. The resulting Pd precipitate contained almost no impurities, such as actinides (U, Np, Pu, Am, Cm), major fission products (Zr, Mo, Tc, Ru, Rh, Ba, Cs, Ce), resulting in the interference-free measurement of Pd with ICP-MS. The amount of Pd per 1 mg of 
U in the sample was 239
9 ng/mg-U.
Saeki, Morihisa*; Matsumura, Daiju; Taguchi, Tomitsugu*; Yomogida, Takumi; Oba, Hironori*
no journal, ,
We are developing wet separation of precious metals using photo-induced particle formation. Previously we demonstrated that this method could effectively separate a palladium (Pd) metal from a mixed solution with a molybdenum (Mo) ion. In this work, we showed that the Mo ion plays a role as a photosensitizer in the photo-induced particle formation of Pd in an acidic condition by time-resolved X-ray fine structure (XAFS) measurement.
Saeki, Morihisa*; Oba, Hironori*; Taguchi, Tomitsugu*; Yokoyama, Jun*; Asai, Shiho; Yomogida, Takumi; Hanzawa, Yukiko; Nakashima, Nobuaki*
no journal, ,
We are developing separation of platinum-group metals from a solution of high-level radioactive waste by laser-induced particle formation. In this report, we will show method and proof-of-principle experiments of the separation using the laser-induced particle formation.
Asai, Shiho; Yomogida, Takumi
no journal, ,
Palladium found in spent nuclear fuel is characterized by having radiopalladium Pd (Half-life: 6.5
10
y). With its long half-life, accurate determination of the amount of Pd in spent nuclear fuel is essential for estimating the radiation effects. However, no experimentally determined concentration has been reported due to the difficulties in obtaining pure palladium form spent nuclear fuel with conventional separation techniques. In this study, Pd in spent nuclear fuel solution was separated by precipitation triggered by photoreduction of Pd(II) with pulsed laser irradiation. About 20 min of the irradiation to the spent nuclear fuel solution provides high Pd recovery of more than 90%. The prepared Pd precipitate was dissolved with aqua regia and measured with ICP-MS. Almost no impurities were detected in the Pd precipitate, resulting in the accurate determination of Pd.
Saeki, Morihisa*; Matsumura, Daiju; Tsuji, Takuya; Yomogida, Takumi; Taguchi, Tomitsugu*; Oba, Hironori*
no journal, ,
Previously we demonstrated that laser-induced particle formation achieved the recovery of Pd particles with a diameter of sub-micrometers. In this work, we studied Pd particle formation by time-resolved X-ray fine structure spectroscopy (XAFS). Increase of irradiation power results in increase of reaction order from 0.82 to 1.39. The result suggests that the pulsed laser irradiation contributes not only to the reduction of the Pd ion but also to the Pd particle growth in the laser-induced particle formation.
Saeki, Morihisa*; Matsumura, Daiju; Tsuji, Takuya; Yomogida, Takumi; Taguchi, Tomitsugu*; Oba, Hironori*
no journal, ,
Irradiation of a nanosecond pulsed UV laser into a solution of palladium ion leads to formation of palladium particles with submicron size (100-800 nm). We investigate formation mechanism of the submicron size particles by time-resolved X-ray absorption fine structure (XAFS) spectroscopy.
Yomogida, Takumi; Asai, Shiho; Saeki, Morihisa*; Hanzawa, Yukiko; Horita, Takuma; Esaka, Fumitaka; Oba, Hironori*; Kitatsuji, Yoshihiro
no journal, ,
Recently, we developed a precipitation-based separation method for the determination of Pd with ICP-MS. However, a pulsed-laser light source is indispensable to form Pd precipitation in the separation method. There were difficulties in handling of a pulsed-laser light source. Simplified irradiation procedure is desirable to facilitate a Pd separation procedure. In this study, we developed a simple Pd separation technique based on photoreduction with Xe lamp irradiation and applied the technique to a simulated HLW solution. The Pd recovery from a simulated HLW solution reached 50%, while 99% of the other 13 elements were removed. These results indicate that selective separation of Pd is achieved with the simplified irradiation procedure.
by multiphoton excitation in alcohol solutionsMatsuda, Shohei; Nakashima, Nobuaki*; Yokoyama, Keiichi; Yatsuhashi, Tomoyuki*; Chosrowjan, H.*; Taniguchi, Seiji*; Somekawa, Toshihiro*
no journal, ,
The photoredox reactions of lanthanides as a photochemical separative technique proposed in the 1970s are expected to be applied for recovery and recycling of rare metals and nuclear fuel reprocessing. In this study, Eu ions in methanol and ethanol solutions were reduced to Eu ions upon irradiation with nanosecond laser pulses. Eu was observed when the laser wavelength was tuned to f-f transition bands at 394 and 465 nm. The formation rate of Eu was proportional to the square of the incident laser intensity, indicating that the photoreduction is induced by a two-photon process. The efficiency of the photoreduction in ethanol was higher than that in methanol.
O / EtOH SolutionSaeki, Morihisa*; Matsumura, Daiju; Yomogida, Takumi; Taguchi, Tomitsugu*; Tsuji, Takuya; Saito, Hiroyuki*; Nakanishi, Ryuzo*; Oba, Hironori*
no journal, ,
When nanosecond pulsed UV laser is irradiated into a HO / EtOH solution of platinum group metal (PGM) ions, PGM particles with sub-micron size are formed. We investigated laser induced particle formation of Pd in the HO / EtOH solution by in situ time-resolved XAFS spectroscopy and showed dependence of the reaction rate of laser-induced particle formation on the laser fluence. The dependence on the laser fluence elucidated that the photons contribute not only to the reduction of the Pd, but also to the autocatalytic growth of the Pd particles.
using ns pulsed UV laser; Dependence of chemical kinetics on laser pulse energySaeki, Morihisa*; Yomogida, Takumi; Matsumura, Daiju; Nakanishi, Ryuzo*; Taguchi, Tomitsugu*; Tsuji, Takuya; Saito, Hiroyuki*; Oba, Hironori*
no journal, ,
In the absence of a photoactivator, the laser-induced particle formation in an HO/ EtOH solution of PdCl was performed by three kinds of irradiation condition using fourth harmonics of the pulsed UV laser (266 nm). In the irradiation, pulsed laser energy was arranged to 5, 10 and 25 mJ, where average laser power is kept to 250 mW. The reaction kinetics of the laser-induced particle formation was observed using dispersive XAFS measurement. About half of Pd ions were reduced with 5 mJ pulsed laser irradiation. In contrast, all Pd ions were reduced with 25 mJ pulsed laser irradiation. The result elucidates that the laser photon contributes to the generation of Pd metals by the multi-photon process.
Matsuda, Shohei; Nakashima, Nobuaki*; Yokoyama, Keiichi; Yatsuhashi, Tomoyuki*; Chosrowjan, H.*; Taniguchi, Seiji*; Somekawa, Toshihiro*
no journal, ,
The photochemical reactions of lanthanide and actinide ions are expected to be utilized for recovery and recycling of rare earths, and nuclear fuel reprocessing. Heading towards research for implementation of photochemical purification, a unified evaluation of the efficiency of multiphoton processes is required. In this study, we have evaluated the fluence dependence of photoreduction of Eu(III) more precisely than before by measuring the beam profile of the excitation laser. The reduction rate of Eu(III)
Eu(II) is proportional to the square of the laser fluence, indicating that the photoreduction of Eu(III) is induced by a two-photon process.
