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Zr determination with isotope dilution ICP-MSAsai, Shiho; Hanzawa, Yukiko; Konda, Miki; Suzuki, Daisuke; Magara, Masaaki; Kimura, Takaumi; Ishihara, Ryo*; Saito, Kyoichi*; Yamada, Shinsuke*; Hirota, Hideyuki*
Talanta, 185, p.98 - 105, 2018/08
Times Cited Count：8 Percentile：31.98(Chemistry, Analytical)Estimating the risks associated with radiation from long-lived fission products (LLFP) in radioactive waste is essential to ensure the long-term safety of potential disposal sites. In this study, the amount of Zr, a LLFP, was determined by ICP-MS after separating Zr from a spent nuclear fuel solution using a microvolume anion-exchange cartridge (TEDA cartridge). The TEDA cartridge achieved highly selective separation of Zr regardless of its small bed volume of 0.08 cm
. The time taken to complete the Zr separation was 1.2 min with a flow rate of 1.5 mL/min, which was 10 times faster than that for a conventional anion-exchange resin column. Almost all the other elements were removed, leading to accurate measurement of Zr. The result connects experimental value to theoretical prediction provided by ORIGEN2, which requires verification. With the measured value, we demonstrated that the theoretical value is reliable enough to estimate radiation risks.
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.
Okubo, Ayako; Shinohara, Nobuo; Magara, Masaaki
Journal of Radioanalytical and Nuclear Chemistry, 314(1), p.231 - 234, 2017/10
Times Cited Count：2 Percentile：19.65(Chemistry, Analytical)The model date of two enriched uranium materials were determined using a new method for nuclear forensics investigation. In this method, the 
Th/
U ratio was calculated without spike addition from measured ratios of Th/Th and U/
U, and calculated Th/U ratio in secular equilibrium. The obtained model date for the low-enriched uranium material was agreed with the known production date within uncertainty. For the highly enriched uranium material, slightly younger model date than the known production date was obtained. The U interference on Th counting in thermal ionization mass spectrometry measurement was suspected as a potential cause.
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.
Si with XPS and XASEsaka, Fumitaka; Nojima, Takehiro; Udono, Haruhiko*; Magara, Masaaki; Yamamoto, Hiroyuki
Surface and Interface Analysis, 48(7), p.432 - 435, 2016/07
Times Cited Count：16 Percentile：39.42(Chemistry, Physical)XPS is widely used for non-destructive chemical state analysis of solid materials. In this method, depth profiling can be carried out by a combination with ion beam sputtering. However, the sputtering often causes segregation and preferential sputtering of atoms and gives inaccurate information. The use of energy-tunable X-rays from synchrotron radiation (SR) enables us to perform non-destructive depth profiling in XPS. Here, the analytical depth can be changed by changing excitation X-ray energy. In the present study, we examined methods to perform depth profiling with XPS by changing excitation energy and XAS by changing electron energy for detection. These methods were then applied to the analysis of native surface oxide layers on MgSi crystals. In this XAS analysis, the peak at 1843.4 eV becomes dominant when the electron energy for detection increases, which implies that Si-O or Si-O-Mg structure is formed as the surface oxide layer on the MgSi.
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.
Konda, Miki; Asai, Shiho; Hanzawa, Yukiko; Magara, Masaaki
JAEA-Technology 2015-054, 22 Pages, 2016/03
JAEA-Technology-2015-054.pdf:3.44MB
Isotope dilution mass spectrometry (IDMS) with ICP-MS is reliable method for determination of Zr-93, which is one of the long-lived fission products found in spent nuclear fuel and high-level radioactive wastes. In order to use an isotope standard solution of zirconium as the spike for IDMS, dissolving a commercially available solid isotope standard is indispensable. Prior to the dissolution of the Zr-91 isotope standard, solubility of metal zirconium in a mixture of HNO
and HF was evaluated using zirconium metal chips. Then, 2 mg of the Zr-91 isotope standard was dissolved with 0.2 mL of 1 M HNO-3 v/v% HF mixed solution, followed by adjusting the concentration of Zr-91 to approximately 1,000 g/g. IDMS, in which a natural isotopic abundance standard solution of zirconium was used as the spike, was employed for the determination of the concentration of Zr-91 in the prepared Zr-91 isotope standard solution. The concentration of Zr-91 in the prepared Zr-91 isotope standard solution was (9.6
1.0) 10
g/g, which is in good agreement with the predicted concentration. This indicates that the Zr-91 metal isotope standard was completely dissolved with sufficient chemical stability. Additionally, no impurities were detected in the prepared Zr-91 isotope standard solution. These positive results denote that the Zr-91 isotope standard solution with the preferable quality for IDMS of Zr-93 can be obtained by the proposed dissolution procedures.
Np content in spent nuclear fuelAsai, Shiho; Hanzawa, Yukiko; Konda, Miki; Suzuki, Daisuke; Magara, Masaaki; Kimura, Takaumi; Ishihara, Ryo*; Saito, Kyoichi*; Yamada, Shinsuke*; Hirota, Hideyuki*
Analytical Chemistry, 88(6), p.3149 - 3155, 2016/03
Times Cited Count：8 Percentile：29.82(Chemistry, Analytical)Neptunium-237 (Np) is one of the major long-lived radionuclides found in spent nuclear fuel. To evaluate the long-term safety of a HLW repository, the Np content in spent nuclear fuel must be determined. In this study, micro-volume anion-exchange porous polymer disk-packed cartridges were prepared for Am-Np separation, which is required prior to the measurement of Np with ICP-MS. Disks with a volume of 0.08 cm were cut out from porous sheets having triethylenediamine (TEDA)-containing polymer chains densely attached on the pore surface. The resulting TEDA-introduced disk cartridge was applied to a spent nuclear fuel sample. The chemical yield of Np was 90.4%, which is sufficiently high for ICP-MS measurement of Np. Compared with the conventional separation technique using commercially available anion-exchange resin columns, the time required to adsorb, wash and elute Np using the TEDA-introduced disk cartridge was reduced by 75%.
Th-U age dating of bulk uranium for nuclear forensicsGaffney, A.*; Hubert, A.*; Kinman, W. S.*; Magara, Masaaki; Okubo, Ayako; Pointurier, F.*; Schorzman, K. C.*; Steiner, R. E.*; Williams, R. W.*
Journal of Radioanalytical and Nuclear Chemistry, 307(3), p.2055 - 2060, 2016/03
Times Cited Count：22 Percentile：89.8(Chemistry, Analytical)In and inter-laboratory measurement comparison study, four laboratories (LLNL, LANL, CEA, JAEA) determined Th-U model ages of uranium certified reference material NBL U050 using isotope dilution mass spectrometry. The model dates determined by the participating laboratories range from 9 March 1956 to 19 October 1957, and are indistinguishable given the associated measurement uncertainties. These model ages are concordant with to slightly older than the known production age of NBL U050, indicating unsufficient purification of U050.
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.
Lee, C.-G.*; Suzuki, Daisuke; Esaka, Fumitaka; Magara, Masaaki; Song, K.*
Talanta, 141, p.92 - 96, 2015/08
Times Cited Count：13 Percentile：44.45(Chemistry, Analytical)Thermal ionization mass spectrometry (TIMS) with a continuous heating technique is known as an effective method for measuring the isotope ratio in trace amounts of uranium. In this study, the analytical performance of thermal ionization mass spectrometry with a continuous heating technique was investigated using a standard plutonium solution (SRM 947). The influence of the heating rate of the evaporation filament on the precision and accuracy of the isotope ratios was examined using a plutonium solution sample at the fg level. Changing the heating rate of the evaporation filament on samples ranging from 0.1 fg to 1000 fg revealed that the influence of the heating rate on the precision and accuracy of the isotope ratios was slight around the heating rate range of 100 to 250 mA/min. All of the isotope ratios of plutonium (SRM 947), Pu/Pu, Pu/Pu, Pu/Pu and Pu/Pu, were measured down to sample amounts of 70 fg. The ratio of Pu/Pu was measured down to a sample amount of 0.1 fg, which corresponds to a PuO particle with a diameter of 0.2 m. Moreover, the signals of Pu could be detected with a sample amount of 0.03 fg, which corresponds to the detection limit of Pu of 0.006 fg as estimated by the 3 
criterion. Pu and Am formed by the decay of Pu could be discriminated owing to the difference in the evaporation temperature. As a result, Pu/Pu as well as Pu/Pu and Pu/Pu in plutonium samples could be measured by TIMS with a continuous heating technique and without any chemical separation processes.
Miyamoto, Yutaka; Yasuda, Kenichiro; Magara, Masaaki
Analyst, 140(13), p.4482 - 4488, 2015/07
Times Cited Count：6 Percentile：21.67(Chemistry, Analytical)Uranium, Thorium, lead, and the lanthanides were automatically and sequentially separated with a single anion-exchange column. This separation was achieved using eluents consisting of simple and highly pure acid mixture of HCl, HNO, acetic acid, and HF. This simple, automatic system is driven with pressurized nitrogen gas, and controlled by a computer program. For an evaluation examination, a reference powdered rock sample was separated by using this system. Abundances of objective elements, including 0.23 ng of lutetium, were accurately determined without corrections of chemical recovery yield or subtraction of processing blank. This separation technique saves time and effort for chemical processing, and it is useful for ultra-trace quantitative and isotopic analyses of elements in small environmental samples.
Esaka, Fumitaka; Suzuki, Daisuke; Magara, Masaaki
Analytical Chemistry, 87(5), p.3107 - 3113, 2015/03
Times Cited Count：13 Percentile：44.45(Chemistry, Analytical)The analysis of uranium particles in environmental samples taken from nuclear facilities is a useful tool to unveil undeclared nuclear activities related to the production of nuclear weapons. An efficient method to analyze isotope ratios of individual uranium particles is thermal ionization mass spectrometry (TIMS) combined with a fission track technique. A drawback in the fission track-TIMS technique is so-called particle-mixing. Here, some uranium particles are measured as a single particle and an averaged isotope ratio is obtained, which may lead to misunderstanding conclusions for source identification. In the present study, micro-sampling under a scanning electron microscope has been added to the procedure of the fission track-TIMS technique. The analysis of a mixed sample containing uranium particles in SRM 950a and CRM U100 materials indicated that the problem of particle mixing was almost avoidable with the proposed technique.
Suzuki, Daisuke; Esaka, Fumitaka; Miyamoto, Yutaka; Magara, Masaaki
Applied Radiation and Isotopes, 96, p.52 - 56, 2015/02
Times Cited Count：15 Percentile：77.56(Chemistry, Inorganic & Nuclear)Isotope ratios of uranium and plutonium in individual U-Pu mixed particles with various U/Pu ratios were determined by thermal ionization mass spectrometry with a continuous heating method without chemical separation. Prior to the measurements, micron-sized U-Pu mixed particles with U/Pu ratios of 1, 5, 10, 18 and 70 were produced by using certified reference materials CRM U-010 (1%
U enriched, NBL) and SRM 947 (NBS) solutions. As a result of isotope ratio analysis, accurate values for U and Pu ratios, except for Pu/Pu, were successfully determined for the particles with all U/Pu ratios. Although some pre-treatment such as chemical separation would need for accurate determination of Pu/Pu isotope analysis, it was shown that this analytical technique has a potential of powerful tool for nuclear safeguards and forensics.
Pu/
U ratios in individual particles by ICP-MS without prior chemical separationEsaka, Fumitaka; Suzuki, Daisuke; Miyamoto, Yutaka; Magara, Masaaki
Microchemical Journal, 118, p.69 - 72, 2015/01
Times Cited Count：8 Percentile：29.03(Chemistry, Analytical)The determination of the time elapsed since the last purification of plutonium with chemical separation gives important information for monitoring nuclear activities related to reprocessing and nuclear weapon production. Although methods for the analysis of plutonium solutions have been extensively studied, few studies were conducted for the measurement of individual particles. In this work, a simple technique was developed for age determination of individual plutonium particles by a combination of single particle dissolution and measurement by inductively coupled plasma mass spectrometry (ICP-MS) without prior chemical separation. The analytical results of individual plutonium particles having an age of 5.98 y indicated that the use of Pu/U ratios allowed for the determination of accurate ages, though that of Pu/U and Pu/U ratios was not suitable because of the contamination of natural uranium during the process of sample preparation.
