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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：50.37(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.
Lee, C. G.; Iguchi, Kazunari; Inagawa, Jun; Suzuki, Daisuke; Esaka, Fumitaka; Magara, Masaaki; Sakurai, Satoshi; Watanabe, Kazuo; Usuda, Shigekazu
Journal of Radioanalytical and Nuclear Chemistry, 272(2), p.299 - 302, 2007/05
Times Cited Count：47 Percentile：93.87(Chemistry, Analytical)no abstracts in English
Usuda, Shigekazu; Yasuda, Kenichiro; Kokubu, Yoko; Esaka, Fumitaka; Lee, C. G.; Magara, Masaaki; Sakurai, Satoshi; Watanabe, Kazuo; Hirayama, Fumio; Fukuyama, Hiroyasu; et al.
International Journal of Environmental Analytical Chemistry, 86(9), p.663 - 675, 2006/08
Times Cited Count：14 Percentile：40.1(Chemistry, Analytical)The IAEA introduced the environmental sample analysis method, as a powerful tool to detect undeclared nuclear activities, into strengthened safeguards system. The principle of the method is that nuclear signatures can be evidenced if trace amount of nuclear materials in environmental samples taken from inside and outside of nuclear facilities are accurately analyzed. Currently, isotope ratios of uranium and plutonium in "swipe" samples are measured, which are collected in nuclear facilities. In future, the subject of environmental sample analysis will expand to soil, sediment, vegetation, water and airborne dust taken from outside of the nuclear facilities. If physical and chemical form of the nuclear materials is identified, we may estimate their origin, treatment process and migration behavior. This paper deals with the developed analytical techniques for the safeguards environmental samples, the current R&D on techniques related to estimation of the physical and chemical form, and possible analytical methodologies applicable to ultra-trace amounts of nuclear materials.
Lee, C. G.; Iguchi, Kazunari; Esaka, Fumitaka; Magara, Masaaki; Sakurai, Satoshi; Watanabe, Kazuo; Usuda, Shigekazu
Nuclear Instruments and Methods in Physics Research B, 245(2), p.440 - 444, 2006/04
Times Cited Count：8 Percentile：50.27(Instruments & Instrumentation)The etching rates of fission track detectors made of polycarbonate containing uranium particles were measured after thermal neutron irradiation with fluence of 810
n/cm
, in order to study the influence of uranium enrichment on the etching rate that was calculated from the weight loss by etching. There is a strong correlation between the etching rate of detector and the enrichment E of uranium particle: the former increases as the latter increases. Particularly, the etching rate per particle was proportional to E
rather than E
, which is probably due to the overlapping of fission tracks. The etching behaviors of detector revealed that the existence of two different etching rate regions, a nonlinear region in the beginning of etching process and a subsequent constant region, which was explained as the opening of fission tracks and the broadening of opened tracks, respectively.
Iguchi, Kazunari; Esaka, Konomi; Lee, C. G.; Inagawa, Jun; Esaka, Fumitaka; Onodera, Takashi; Fukuyama, Hiroyasu; Suzuki, Daisuke; Sakurai, Satoshi; Watanabe, Kazuo; et al.
Radiation Measurements, 40(2-6), p.363 - 366, 2005/11
Times Cited Count：11 Percentile：59.86(Nuclear Science & Technology)In particle analysis for safeguards environmental samples, the fission track technique is very important to detect sub-micrometer particles containing uranium. In the technique the authors developed, the particles were recovered onto the polycarbonate membrane filter. The filter was dissolved in solvent and dried to form a thin film of detector, in which the particles were confined. After thermal neutron irradiation and etching, the particles of interest in the detector were easily identified with fission tracks, and were picked up for isotope ratio analysis. It was found, however, that the particles in the vicinity of the detector surface may fall off during the etching process. Therefore, optimization of the etching condition is required. In this work, the effects of etching time and enrichment of uranium in particles were investigated. Preliminary results suggest that etching time should be shorter with the increase in the enrichment.
Esaka, Konomi; Esaka, Fumitaka; Inagawa, Jun; Iguchi, Kazunari; Lee, C. G.; Sakurai, Satoshi; Watanabe, Kazuo; Usuda, Shigekazu
Japanese Journal of Applied Physics, Part 2, 43(7A), p.L915 - L916, 2004/07
Times Cited Count：41 Percentile：78.91(Physics, Applied)An effective method for isotope ratio analysis of individual particles containing uranium in safeguards swipe samples was developed by using a fission track (FT) technique combined with thermal ionization mass spectrometry (TIMS). The particles in the sample were directly recovered onto a polycarbonate membrane filter, which was set in a filtration system. After the particle recovery, the filter was dissolved to form a non-coated FT detector film containing the particles. Individual particles containing uranium were then identified by the observation of fission tracks created by thermal neutron irradiation. By combination of the FT technique with TIMS, isotope ratios of uranium for individual particles in the swipe sample prepared from a uranium standard reference material could be effectively determined.
Esaka, Fumitaka; Watanabe, Kazuo; Magara, Masaaki; Hanzawa, Yukiko; Usuda, Shigekazu
Journal of Trace and Microprobe Techniques, 19(4), p.487 - 496, 2001/11
Times Cited Count：9 Percentile：30.1(Chemistry, Analytical)The capability of total-reflection X-ray fluorescence spectrometry (TXRF) technique was studied to screen a swipe sample for uranium content, which was employed to decide on the further isotopic ratio measurements by secondary ion mass spectrometry (SIMS) for safeguards environmental sample analysis. A part of the measurement system of TXRF was modified to be able to use the same glassy carbon carrier for SIMS analysis. Particles in the swipe sample were recovered on the carbon carrier. The relative sensitivities of 11 elements including uranium were determined using selenium as an internal standard. The detection limit of uranium was 0.4 ng. The screening technique studied was applied to the practical swipe samples taken from the laboratories. The results confirm that TXRF can be a promising screening technique for uranium in swipe samples for safeguards environmental sample analysis.
Yamane, Tsuyoshi; ; Akino, Fujiyoshi; Kaneko, Yoshihiko
Journal of Nuclear Science and Technology, 27(2), p.122 - 132, 1990/02
no abstracts in English
;
JAERI-M 87-023, 10 Pages, 1987/02
no abstracts in English
; Minato, Kazuo; Ikawa, Katsuichi; ;
Journal of Nuclear Science and Technology, 18(11), p.887 - 894, 1982/00
Times Cited Count：4 Percentile：52.53(Nuclear Science & Technology)no abstracts in English
