Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
ssbauer spectroscopyMorii, Shiori
Hosha Kagaku, (51), p.21 - 23, 2025/03
To understand the influence of redox properties of structural Fe in clay minerals on removal and immobilization of radionuclides in geological disposal environment, we investigated redox and structural properties of Fe in clay minerals at reducing conditions. Clay mineral sample was reduced by controlled-potential electrolysis at -0.5 V vs the standard hydrogen electrode. Redox state and structural properties of Fe in this prepared clay mineral sample was investigated by Fe-57 Mssbauer spectroscopy. From the Mssbauer spectra, we found that structural Fe(III) in octahedral sheets was reduced to Fe(II). This fundamental information about the Fe in clay minerals will contribute to technical reliabilities of geological disposal.
Yomogida, Takumi; Ouchi, Kazuki; Morii, Shiori; Oka, Toshitaka; Kitatsuji, Yoshihiro; Koma, Yoshikazu; Konno, Katsuhiro*
Scientific Reports (Internet), 14, p.14945_1 - 14945_11, 2024/06
Times Cited Count：1 Percentile：36.75(Multidisciplinary Sciences)Particles containing alpha (
) nuclides were identified from sediment in stagnant water in the Unit 3 reactor building of the Fukushima Daiichi Nuclear Power Station (FDiNPS). We analyzed different concentrations of alpha nuclides samples collected at two sampling sites, torus room and Main steam isolation valve (MSIV) room. Most of the -nuclides in the stagnant water samples of the torus room and the MSIV room were present in particle fractions larger than 10 
m. We detected uranium-bearing particles in m-size by scanning electron microscopy-energy dispersive X-Ray (SEM-EDX) observation. Other short lived -nuclides were detected by alpha track detection. The -nuclide-containing particles with several tens to several hundred m in size were mainly comprised iron (Fe) by SEM-EDX analysis. This study clarifies that the morphologies of U and other -nuclides in the sediment of stagnant water in the FDiNPS's Unit 3 reactor building.
Morii, Shiori; Yomogida, Takumi; Asai, Shiho*; Ouchi, Kazuki; Oka, Toshitaka; Kitatsuji, Yoshihiro
KEK Proceedings 2023-2, p.132 - 137, 2023/11
New analytical method of a combination of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and isotope dilution mass spectrometry (IDMS) for quantification of Zr isotopes in a solid sample was investigated. Solid Zr-isotope reference was added to a simulated radioactive waste sample as a spike, then Zr isotope ratio was measured by LA-ICP-MS. As a result, we successfully quantify Zr isotopes in the simulated radioactive waste sample by new IDMS. There is a possibility that this new method can be applied for quantification of Zr-93 in difficult to dissolve radioactive wastes.
Morii, Shiori; Yomogida, Takumi; Asai, Shiho*; Ouchi, Kazuki; Oka, Toshitaka; Kitatsuji, Yoshihiro
Bunseki Kagaku, 72(10.11), p.441 - 448, 2023/10
Rapid analytical method for the determination of Zr-93 in radioactive wastes has been developed. Laser ablation (LA)-ICP-MS was applied to the analysis of Zr isotopes in simulated high-level radioactive waste (HLW). Sample preparation time was dramatically reduced by using a DGA resin as the adsorbent for Zr. Direct quantification of Zr isotopes in this resin sample was carried out by LA-ICP-MS. Laser settings were optimized to obtain a reliable isotope ratio of the sample by LA-ICP-MS. Quantification of Zr isotopes in the simulated HLW solution by isotope dilution mass spectrometry (IDMS) was examined. The amount of Zr-90 in the sample obtained by IDMS corresponded to a value calculated from the given concentration of Zr in the sample within uncertainty. Thus, this method can be applied for the quantification of Zr-93 in radioactive wastes.
Yomogida, Takumi; Saeki, Morihisa*; Morii, Shiori; Oba, Hironori*; Kitatsuji, Yoshihiro
Analytical Sciences, 37(12), p.1843 - 1846, 2021/12
Times Cited Count：1 Percentile：3.83(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.
-emitting nuclides analysis of the stagnant water including sediments in Fukushima Daiichi NPS, 11; Dissolution of fine particles and -emitting nuclides by immersing in an acid solutionYomogida, Takumi; Morii, Shiori; Oka, Toshitaka; Koma, Yoshikazu; Kitatsuji, Yoshihiro
no journal, ,
Most of -emitting nuclides in sediment of stagnant water exist as iron particles and U particles. An attempt was made to selectively dissolve iron particles by immersion in an acid solution and investigate the abundance of -nuclides in these particles. Most of the uranium in the sediment is present on iron particles like other alpha nuclides, and the proportion of uranium present as U particles is estimated to be 5% or less.
-emitting nuclides analysis of the stagnant water including sediments in Fukushima Daiichi NPS, 7; Analysis of U and Np in the stagnant water at the Unit 1 reactorMorii, Shiori; Ouchi, Kazuki; Yomogida, Takumi; Oka, Toshitaka; Kitatsuji, Yoshihiro; Koma, Yoshikazu; Konno, Katsuhiro*
no journal, ,
The existence of -emitting nuclides on the sediment contained in the stagnant water of the Unit 1 reactor of Fukushima Daiichi Nuclear Power Station was investigated. The stagnant water was fractionated using filters and U and Np concentrations in the solid fraction and filtrate were determined using ICP-MS. Most of them were present in the fraction which pore size is larger than 10 m, like those in the Units 2 and 3. Some were present in the stagnant water on fine particles or ions smaller than 0.1 m.
-emitting nuclides analysis of the stagnant water including sediments in Fukushima Daiichi NPS, 9; Analysis of fine particle containing -emittersYomogida, Takumi; Ouchi, Kazuki; Morii, Shiori; Oka, Toshitaka; Kitatsuji, Yoshihiro; Koma, Yoshikazu; Konno, Katsuhiro*
no journal, ,
Fine particles containing -nuclides in sediment of stagnant water of Unit 1 were analyzed. We have detected several sub-m to a few m size particles containing U by SEM-EDX, these particles contain elements derived from fuel cladding materials such as Zr, suggesting the possibility that these particles are fine fuel debris. On the other hand, by the alpha-track method, we have detected fine particles main composed of iron oxide with a diameter from 10 m to a few hundred m, which attached Pu, Am and Cm on their surface. These results indicated that the existence forms of -nuclides were similar to those in the stagnant water of torus room in Units 2 and 3.
ssbauer spectroscopyMorii, Shiori; Yomogida, Takumi; Nakada, Masami; Oka, Toshitaka; Kitatsuji, Yoshihiro; Takahashi, Yoshio*
no journal, ,
To understand the influence of redox properties of structural Fe in clay minerals on removal and immobilization of radionuclides in geological disposal environment, we are investigating redox and structural properties of Fe in clay minerals over a large range of redox potentials. Clay mineral sample was reduced by controlled-potential electrolysis. Redox state and structural properties of Fe in this prepared clay mineral sample was investigated by Fe-57 Mssbauer spectroscopy. From the Mssbauer spectra, we obtained information about the amount of structural Fe(II) which reduced from structural Fe(III) and structural properties of Fe(II).
Morii, Shiori; Yomogida, Takumi; Nakada, Masami; Oka, Toshitaka; Kitatsuji, Yoshihiro; Takahashi, Yoshio*
no journal, ,
The purpose of this research is to understand the redox reaction between structural Fe in clay minerals and concomitant elements in environments. Then, we are investigating redox properties of Fe in clay minerals over a large range of redox potentials (Eh) and pH. Redox state of the Fe-bearing clay mineral sample (nontronite) was controlled by potential electrolysis at various Eh-pH conditions. From this experiment, we obtained information about the dependence of the redox state of structural Fe in clay minerals on Eh and pH conditions.
Kitatsuji, Yoshihiro; Fukaya, Hiroyuki; Haraga, Tomoko; Oka, Toshitaka; Otake, Yoshinori; Tambo, Masaki; Inada, Arisa; Aono, Ryuji; Kinase, Akari; Ikarugi, Riko; et al.
no journal, ,
To proceed with the decommissioning of Fukushima Daiichi Nuclear Power Station Accident (1F), it is necessary to secure human resources for radionuclide analysis, which is a prerequisite for the safe treatment and disposal of treated water and waste containing radionuclides generated as a result of the decommissioning. The Nuclear Science Research Institute of JAEA, together with the Fukushima Research and Engineering Institute, has started a project to train analytical personnel who will be responsible for decommissioning in the future. In this presentation, we will introduce the training of analytical operators, managers, and engineers for young staff members and our efforts using the summer intern program.
Yanagisawa, Kayo; Ikarugi, Riko; Morii, Shiori; Oka, Toshitaka; Kitatsuji, Yoshihiro; Fukaya, Hiroyuki; Haraga, Tomoko; Otake, Yoshinori; Tambo, Masaki; Inada, Arisa; et al.
no journal, ,
no abstracts in English
ssbauer spectroscopyMorii, Shiori; Yomogida, Takumi; Nakada, Masami; Oka, Toshitaka; Kitatsuji, Yoshihiro; Takahashi, Yoshio*
no journal, ,
no abstracts in English
Morii, Shiori; Yomogida, Takumi; Ouchi, Kazuki; Kitatsuji, Yoshihiro
no journal, ,
Zr-93 is one of the long-lived fission products in radioactive waste. To ensure the long-term safety of radioactive waste, estimating the risks associated with radiation from Zr-93 is essential. In previous studies, determination methods of Zr-isotope in liquid sample using ICP-MS were developed. However, those methods were complicated and time consuming. Then, this research is developing the new method that determining Zr-isotope in solid sample using LA-ICP-MS. Sr, Mo, Ru are needed to separate from Zr, because those elements are isobars and interfere the quantitative of Zr. DGA resin was used to separate Zr from simulated HLW solution. Diluted simulated HLW solution was loaded onto the DGA resin cartridge. 2 M nitric acid and 4 M nitric acid were loaded onto the resin and interference elements were eluted from the resin. After nitric acid was loaded, more than 99% of Zr was retained on the resin. Thus, this method enables preparing solid Zr sample for determination of Zr-isotope.
Morii, Shiori; Yomogida, Takumi; Asai, Shiho*; Ouchi, Kazuki; Oka, Toshitaka; Kitatsuji, Yoshihiro
no journal, ,
We are developing a rapid analytical method to analyze Zr-isotopes in solid sample using laser ablation (LA)-ICP-MS. In this study, we examined the proper method for sample preparation, optimized the laser settings for the measurement, and successfully demonstrated that the developed method using LA-ICP-MS enables us to analyze Zr-isotopes rapidly.
-emitting nuclides analysis of the stagnant water including sediments in Fukushima Daiichi NPS, 1; -emitting nuclides in the stagnant water at the unit 3 reactor of Fukushima Dai-ichi NPSOuchi, Kazuki; Oka, Toshitaka; Yomogida, Takumi; Morii, Shiori; Kitatsuji, Yoshihiro; Koma, Yoshikazu; Konno, Katsuhiro*
no journal, ,
To understand the existence of -nuclides in the particulate solids contained in the stagnant water in the unit 3 reactor of Fukushima Daiichi Nuclear Power Station, the stagnant water was classified by particle size using filters with pore diameters of 10, 1, 0.1, and 0.02~m, and U and Np concentrations in the solid fraction and filtrate were investigated using ICP-MS. Both nuclides were present in large particles larger than 10~m, and some were present in the stagnant water on fine particles or ions smaller than 0.02~m.
-emitting nuclides analysis of the stagnant water including sediments in Fukushima Daiichi NPS, 2; Detection of fine particle containing -emitters by SEM-EDX and alpha TrackYomogida, Takumi; Ouchi, Kazuki; Morii, Shiori; Oka, Toshitaka; Kitatsuji, Yoshihiro; Koma, Yoshikazu; Konno, Katsuhiro*
no journal, ,
To investigate the morphology of -nuclides in solid fraction of the stagnant water in the Fukushima Daiichi Nuclear Power Station's Unit 3 reactor, we tried to detect particles containing -nuclides by scanning electron microscopy-X-ray detection (SEM-EDX) and the alpha track method. As a result of SEM-EDX observation, several sub-m to 10 m size particles containing U were identified. The particles containing alpha emitters were identified by alpha-track method. These particles with few hundred m in diameter were mainly composed of iron.
