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Tomita, Ryohei; Tomita, Jumpei; Suzuki, Daisuke; Yasuda, Kenichiro; Miyamoto, Yutaka
Hosha Kagaku, (48), p.1 - 15, 2023/09
Secondary Ion Mass Spectrometry (SIMS) is the method to detect secondary ions produced by the sputtering of primary ions. SIMS is one of effective method to measure isotopic composition of particles containing nuclear material in environmental sample for safeguards. We are a group member of the International Atomic Energy Agency (IAEA)'s network of analytical laboratories and have developed analytical techniques using SIMS and other mass spectrometers for nuclear safeguards. We will introduce the principle of SIMS and analytical techniques developed by our group to measure isotopic composition of uranium particles which having a particle diameter of micron order in environmental sample for safeguards.
Miyamoto, Yutaka; Suzuki, Daisuke; Tomita, Ryohei; Tomita, Jumpei; Yasuda, Kenichiro
Isotope News, (786), p.22 - 25, 2023/04
no abstracts in English
Tomita, Ryohei; Tomita, Jumpei; Yomogida, Takumi; Suzuki, Daisuke; Yasuda, Kenichiro; Esaka, Fumitaka; Miyamoto, Yutaka
KEK Proceedings 2022-2, p.108 - 113, 2022/11
Automated Particle Measurement (APM) is the first measurement of environmental sample for safeguard purpose. APM tells us the number of particles in sample, their enrichment and their location. Precision and accuracy of APM is easily affected by particle condition. We have investigated how influential baking temperature in sample preparation are for uranium secondary ion quantity, uranium hydride generation and particle crystallinity. Our experimental results showed that baking temperature of 800
C reduced uranium secondary ion quantity to 33% compared with baking at 350C. Uranium hydride generation ratio of the sample baked at 850C was also 4 times higher than the sample baked at 350C. Baking at 850C raised only crystallinity of uranium particles. Baking sample at too high temperature caused less uranium secondary ion generation and much more uranium hydride generation. It made precision and accuracy of APM worse. In our experiment, baking at 350C is suitable for uranium particles in the safeguards sample.
Tomita, Jumpei; Tomita, Ryohei; Suzuki, Daisuke; Yasuda, Kenichiro; Miyamoto, Yutaka
KEK Proceedings 2022-2, p.154 - 158, 2022/11
Precise determination of minor U isotopes (
U and 
U) of particles from the safeguard environmental samples is powerful method for detecting the undeclared nuclear activities. In this study, preparation method of U particle was examined to utilize for the minor U isotope determination. The porous silica particles were used as the particle matrix and lutetium was mixed to the impregnation solution as U impregnation indicator for the particle picking. The result of the Scanning Electron Microscope indicated that the contacting the solution with Si particles overnight gently could produce the impregnated particles effectively rather than the mixing them with PFA stick.
Yomogida, Takumi; Kitatsuji, Yoshihiro; Miyamoto, Yutaka
KEK Proceedings 2022-2, p.148 - 153, 2022/11
The Research Group for Safeguards Analytical Chemistry is currently developing a method to analyze the chemical state of uranium particles in environmental samples collected at nuclear facilities using micro-Raman spectroscopy. The chemical state of uranium particles in environmental samples can be partially oxidized by long-term exposure to air. It is necessary to develop a method to analyze the chemical state of the entire particle. In this study, uranium dioxide stored under atmospheric conditions was analyzed by micro-Raman mapping. The Raman spectra showed that uranium peroxide was locally present in the UO
particle. The Raman peaks originating from the structure of UO around 570 cm
and 1150 cm could not be observed in the point analysis of the particle center. On the other hand, in mapping analysis, Raman peaks originating from the structure of UO can be observed from the same particle, demonstrating that Raman mapping analysis is an effective method for analyzing the chemical state of the entire particle.
Tomita, Ryohei; Tomita, Jumpei; Yomogida, Takumi; Suzuki, Daisuke; Yasuda, Kenichiro; Esaka, Fumitaka; Miyamoto, Yutaka
KEK Proceedings 2021-2, p.146 - 150, 2021/12
no abstracts in English
Suzuki, Daisuke; Tomita, Ryohei; Tomita, Jumpei; Esaka, Fumitaka; Yasuda, Kenichiro; Miyamoto, Yutaka
Journal of Radioanalytical and Nuclear Chemistry, 328(1), p.103 - 111, 2021/04
Times Cited Count：3 Percentile：45.99(Chemistry, Analytical)An analytical technique was developed to determine the age of uranium particles for safeguards. After the chemical separation of uranium and thorium, the 
Th/
U ratio was measured using single-collector inductively coupled plasma mass spectrometry and a U-based reference material comprising a certain amount of 
Th as a progeny nuclide of U. The results allowed us to determine the purification age of two certified materials, i.e., U-850 and U-100, which was in good agreement with the reference purification age (61 y). Moreover, the age of a single U-850 particle was determined with a difference of -28 to 2 years from the reference date.
Esaka, Fumitaka
Bunseki, 2018(10), p.408 - 411, 2018/10
Recent development of analytical techniques for identification of particles containing nuclear materials, isotope ratio analysis of uranium and plutonium using mass spectrometry, and age determination is described in this paper. These techniques are successfully applied to the trace analysis for nuclear non-proliferation.
Miyamoto, Yutaka; Yasuda, Kenichiro
Journal of Nuclear and Radiochemical Sciences (Internet), 18, p.13 - 15, 2018/07
A sequential separation technique using an anion-exchange column developed in the previous works have the potential to completely separate picograms of Am from the lanthanides using mixtures of acetic acid, hydrochloric acid, and nitric acid as the eluents, without any functional ligands or special columns. This experimental result implies that ultra-trace actinides, including Am, Pu, U, and Th in environmental samples can be sequentially separated by combination of these mixed-media eluents and an anion exchange column.
Yomogida, Takumi; Esaka, Fumitaka; Magara, Masaaki
Analytical Methods, 9(44), p.6261 - 6266, 2017/11
Times Cited Count：9 Percentile：55.65(Chemistry, Analytical)A combination of micro-sampling, micro-Raman spectroscopy (MRS), and secondary ion mass spectrometry (SIMS) was applied to the characterization of individual uranium particles. Reference particles with U
O
(NBL CRM U010) and UO were identified by scanning electron microscopy combined with energy dispersive X-ray detection (SEM-EDX) and transferred onto grassy carbon substrates by micro-sampling. The crystalline phases of the reference particles with diameters ranging from 1 
m to 5 m were determined non-destructively by using MRS thanks to the optimization of laser power at the measurement. Isotope ratios were also determined with SIMS after the MRS analysis and were consistent with values in the literature. These results indicate that chemical forms and isotope ratios of individual uranium particles as small as 1 m can be analyzed efficiently by using the proposed method.
Miyamoto, Yutaka; Yasuda, Kenichiro; Suzuki, Daisuke; Esaka, Fumitaka; Magara, Masaaki
KEK Proceedings 2017-6, p.292 - 298, 2017/11
Our updated analytical techniques of ultra-trace plutonium in the IAEA environmental samples by ICP-MS were mentioned. Some careful techniques to accurately determine ultra-trace plutonium in the range of femto-grams to pico-grams were introduced. The uncertainties of analytical results were estimated according to the GUM concept. Our trials of determination of sub-femto grams americium in an environmental sample were also mentioned.
Esaka, Fumitaka
Analytical Sciences, 33(10), p.1097 - 1098, 2017/10
Times Cited Count：4 Percentile：83.2(Chemistry, Analytical)Inductively coupled plasma-mass spectrometry (ICP-MS) is widely used in various fields such as environmental, geological, and clinical sciences. In this report, recent advances of the ICP-MS analysis and expected applications are described.
Pu/
Pu in individual U-Pu mixed oxide particles by means of a combination of alpha spectrometry and ICP-MSEsaka, Fumitaka; Yasuda, Kenichiro; Suzuki, Daisuke; Miyamoto, Yutaka; Magara, Masaaki
Talanta, 165, p.122 - 127, 2017/04
Times Cited Count：15 Percentile：52.34(Chemistry, Analytical)The isotope ratios of Pu/Pu, 
Pu/Pu, 
Pu/Pu, and 
Pu/Pu were measured for individual Pu and U-Pu mixed oxide particles by a combination of alpha spectrometry and inductively coupled plasma mass spectrometry (ICP-MS). As a consequence, we were able to determine the Pu/Pu, Pu/Pu, and Pu/Pu isotope ratios with ICP-MS after particle dissolution and chemical separation of uranium, plutonium and americium with UTEVA resins. Furthermore, Pu/Pu isotope ratios were able to be calculated by using both the Pu/(Pu+Pu) activity ratios that had been measured through alpha spectrometry and the Pu/Pu isotope ratios determined through ICP-MS. Therefore, the combined use of alpha spectrometry and ICP-MS is useful in determining plutonium isotope ratios, including Pu/Pu, in individual U-Pu mixed oxide particles.
Miyamoto, Yutaka; Yasuda, Kenichiro; Magara, Masaaki
Journal of Radioanalytical and Nuclear Chemistry, 309(1), p.303 - 308, 2016/07
Times Cited Count：2 Percentile：19.71(Chemistry, Analytical)The technique of sequential separation for U, Th, Pb, lanthanides and Pu using a single anion-exchange column and mixed acids media were developed. An automatic system utilizing a small column and pressurized gas was assembled for this sequential separation. By adjusting the eluent chemical composition for Pu separation, this separation technique has been achieved. Some pieces of tree ring sample were digested, and ultra-trace U and Pu in the samples were separated by this system. The analytical results of U and Pu measured by mass spectrometry will be mentioned.
Esaka, Fumitaka; Magara, Masaaki
Mass Spectrometry Letters, 7(2), p.41 - 44, 2016/06
Secondary ion mass spectrometry (SIMS) is a promising tool to measure isotope ratios of individual uranium particles in environmental samples for nuclear safeguards. However, the analysis requires prior identification of a small number of uranium particles that coexist with a large number of other particles without uranium. In the present study, this identification was performed by scanning electron microscopy -energy dispersive X-ray analysis with automated particle search mode. The analytical results for an environmental sample taken at a nuclear facility indicated that the observation of backscattered electron images with 
1000 magnification was appropriate to efficiently identify uranium particles. Lower magnification (less than 500) made it difficult to detect smaller particles of approximately 1 m diameter.
Esaka, Fumitaka; Suzuki, Daisuke; Yomogida, Takumi; Magara, Masaaki
Analytical Methods, 8(7), p.1543 - 1548, 2016/02
Times Cited Count：8 Percentile：50.61(Chemistry, Analytical)The isotope ratio analysis of individual uranium particles in environmental samples taken at nuclear facilities is important to clarify their origins for nuclear safeguards. In the present study, automated particle screening was used to select uranium particles prior to precise isotope ratio analysis by thermal ionization mass spectrometry (TIMS). As a result, molecular ion interferences on the uranium mass region were able to be almost completely avoided in the analysis of real inspection samples using APM-TIMS. Therefore, the performance of APM-TIMS was sufficient for obtaining isotope ratio data of individual particles without molecular ion interferences.
Esaka, Fumitaka; Suzuki, Daisuke; Miyamoto, Yutaka; Magara, Masaaki
Journal of Radioanalytical and Nuclear Chemistry, 306(2), p.393 - 399, 2015/11
Times Cited Count：6 Percentile：45.92(Chemistry, Analytical)An analytical technique was developed by a combination of single particle dissolution, chemical separation of uranium, plutonium and americium with extraction chromatography using UTEVA resins and measurement with inductively coupled plasma mass spectrometry (ICP-MS). This method was applied to plutonium isotope ratio analysis of individual U-Pu particles with U/Pu ratios ranging from 1 to 70. Consequently, Pu/Pu, Pu/Pu and Pu/Pu isotope ratios were successfully determined, while it was impossible to determine Pu/Pu ratios due to the high process blank values on m/z 238.
Miyamoto, Yutaka; Yasuda, Kenichiro; Magara, Masaaki
KEK Proceedings 2015-4, p.44 - 48, 2015/11
We developed an automatic system for sequential separation with an anion-exchange column to simply and quickly separate less than pico-grams of ultra-trace U, Th, Pb, the lanthanide, and Pu in an environmental sample without foreign contamination. The objective sequential separation of ultra-trace multi-elements succeeded by choosing the HCl-HF mixture based acetic acid for Th separation and the HCl-diluted HF mixture for Pu separation. The objective elements in a multi-elements mixture were completely separated for 6 h 15 min by use of the automatic system and the optimized separation condition.
Miyamoto, Yutaka; Suzuki, Daisuke; Esaka, Fumitaka; Magara, Masaaki
Analytical and Bioanalytical Chemistry, 407(23), p.7165 - 7173, 2015/09
Times Cited Count：8 Percentile：31.37(Biochemical Research Methods)Age of individual uranium-plutonium mixed particles with various U/Pu atomic ratios were determined by inductively-coupled plasma mass spectrometry. Micron-sized particles were prepared from U and Pu certified reference materials. The Pu reference was stored for 4-6 years since the last purification. The Pu purification age was obtained from the Am/Pu ratio which was calculated from the product of three measured ratios of Pu and Am isotopes in the eluted fractions. Am, U and Pu in a sample solution were sequentially separated a small anion-exchange column. The Am/Pu ratio was accurately determined by spiking pure 
Am to the sample solution. The determined age of particles with various U/Pu ratios was in good agreement with the expected age with high accuracy and high precision.
Esaka, Fumitaka
Ekisupato Oyo Kagaku Sirizu; Kiki Bunseki, p.119 - 135, 2015/09
Bulk analysis has been conventionally used for measuring solid materials. In contrast, surface analysis is extensively used for analyzing chemical compositions and chemical states of solid surface. The surface compositions often differ from those of bulk materials. Recently, doping of impurity elements and deposition of thin films on the surface of the materials are key techniques to fabricate functional materials. Therefore, surface analysis becomes important to characterize such materials. In this paper, the principle and feature of some surface analytical techniques are described.
