100 ng. Thermal Ionization Mass Spectrometry, TIMS. International Target Values, ITV TIMS U 1 TIMS TRITON : 0.

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1 BNSEKI KAGAK Vol. 67, No. 11, pp The Japan Society for Analytical Chemistry , Thermal Ionization Mass Spectrometry, TIMS 1 6 International Target Values, ITV TIMS TIMS 1 : : ng 2000 K K TRITON : 0.7 mm : 18.5 mm : mm TM-1000 VHX- 600

2 682 B N S E K I K A G A K Vol Table 1 TIMS measurement conditions Filament type Function Signal Ionization Filament (Rhenium) Mass calibration by 187 Re (Peak center, Focus) Re ionization during measurement 50 mv 150 mv Mass calibration by 238 (Peak center, Focus) 30 mv Fig. 1 Schematic diagram of the contact angle measurement system 2 2 New Brunswick Laboratory NBL CRM O 8, 235 : atom mg CRM mol L 1 40 ml mol L ml 193 mg L 1 ADVANTEC RFD240NA MILLIPORE Milli-Q Academic A Pa 4.5 A A K kv Fig. 1 1 μl θ JIS 17 θ/ Evaporation filament (Tungsten) Cup Configuration Integration Time Data acquisition start (Heat slope: 40 ma/cycle) Max pilot Data acquisition stop (Max current) μl 193 ng A 3.0 A 30 Table 1 Total Evaporation, TE mv 30 V 5500 ma L2 L1 C H1 H s A Fig Fig

3 : 683 Fig. 3 Effect of the Joule-heating times on the contact angle The contact angles of 3 filaments were measured in each Joule-heating time. Fig. 2 SEM images of a tungsten filament without Joule-heating and in each Joule-heating times of (a) 20 min, (b) 60 min and (c) 120 min at 1000 and at fold magnification Fig /min /min Fig

4 684 B N S E K I K A G A K Vol Fig. 4 Optical microscope images of the tungsten filament without Joule-heating and in different Jouleheating times of (a) 20 min, (b) 60 min and (c) 120 min at 1000 and at fold magnification Fig. 5 Comparison of the relative difference for 235 / 238 of the CRM obtained by using filaments with different Joule-heating times The number of measured filaments were (a) n = 20, (b) n = 20 and (c) n = 19, respectively. Error bars show 2 σ. 3 4 Fig / , , CRM / Fig. 6 Relation between the current of the evaporation filament and 235 / 238 obtained by using filaments with different Joule-heating times of (a) 20 min, (b) 60 min and (c) 120 min n n n Fig ma 235 CRM CRM 010

5 : ma CRM ) Safeguards techniques and equipment edition. Vienna : International Atomic Energy Agency, 2011., p. 87 (2011), (IAEA Library Cataloguing in Publication Data). 2) ISO 8299, Nuclear fuel technology Determination of the isotopic and elemental uranium and plutonium concentrations of nuclear materials in nitric acid solutions by thermal-ionization mass spectrometry (2005). 3) ASTM C , Standard Test Method for Determination of ranium Content and Isotopic Composition by Isotope Dilution Mass Spectrometry (2011). 4) ASTM C , Standard Test Method for Determination of ranium or Plutonium Isotopic Composition or Concentration by the Total Evaporation Method sing a Thermal Ionization Mass Spectrometer (2014). 5) S. Bürger, S. D. Balsley, S. Baumann, J. Berger, S. F. Boulyga, J. A. Cunningham, S. Kappel, A. Koepf, J. Poths : Int. J. Mass Spectrom., 311, 40 (2012). 6) S. Boulyga, S. Konegger-Kappel, S. Richter, L. Sangély : J. Anal. At. Spectrom., 30, 1469 (2015). 7) K. Zhao, M. Penkin, C. Norman, S. Balsley, K. Mayer, P. Peerani, C. Pietri, S. Tapodi, Y. Tsutaki, M. Boella, G. Renha Jr., E. Kuhn : International Target Values 2010 for Measurement ncertainties in Safeguarding Nuclear Materials, STR-368, (2012), (International Atomic Energy Agency, Vienna). 8) : (Bunseki), 2016, 46. 9) H. P. Jong, C. Inhee, S. Kyuseok : Mass Spectrom. Lett., 1, 17 (2010). 10) M. H. Studier, E. N. Sloth, L. P. Moore : J. Phys. Chem., 66, 133 (1962). 11) N. Sasaki, K. Kubo, M. Asano, S. Magari : Mass Spectroscopy, 17, 745 (1969). 12) M. Kraiem, K. Mayer, T. Gouder, A. Seibert, T. Wiss, J. P. Hiernaut : J. Anal. At. Spectrom., 25, 1138 (2010). 13) J. M. Mannion, C. R. Shick, G. A. Fugate, M. S. Wellons, B. A. Powell, S. M. Husson : Talanta, 168, 183 (2017). 14) : 80, 341 (2016). 15) W. D. Callister, Jr., D. G. Rethwisch : Material Science and Engeering 7 th edition, p. 198 (2007), (Wiley). 16) : JAERI-Tech , p. 8 (1999), ( ). 17) JIS R 3257, (1999). 18) H. Nakae, R. Inui, Y. Hirata, H. Saito : Acta mater., 46, 2313 (1998).

6 686 B N S E K I K A G A K Vol Effect of Surface Conditions of the Filament sed in Thermal Ionization Mass Spectrometer on an ranium Isotopic Measurement Shigeo TAGCHI 1, Hironari MIYACHI 1,2, Kazushi HORIGOME 1, Masahiko YAMAMOTO 1 and Takehiko KNO 1 1 Nuclear Fuel Cycle Engineering Laboratories, Sector of Decommissioning and Radioactive Waste Management, Japan Atomic Energy Agency (JAEA), 4-33, Oaza muramatsu, Tokai-mura, Nka-gun, Ibaraki Present address: Reprocessing Plant, Japan Nuclear Fuel Limited (JNFL), 4-108, Aza Okitsuke, Obuchi, Rokkasho-mura, Kamikita-gun, Aomori (Received May 10, 2018; Accepted July 9, 2018) Prior to the coating of a sample to a filament surface, a Joule-heating treatment of the filament was performed to remove any impurities from the filament and to minimize the influence of the background in thermal ionization mass spectrometry. In this work, the effect of the surface condition of the tungsten filament induced by the Joule-heating treatment on an uranium isotopic ( 235 / 238 ) measurement has been investigated. By the Joule-heating treatment, crystal grains were formed on the filament surface, and the filament surface became smooth. It was found that by extending the Joule-heating time, the surface became smoother and the precision of uranium isotopic ( 235 / 238 ) measurement was improved. Keywords: thermal ionization mass spectrometry; tungsten filament; precision; isotopic; uranium.