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Journal Articles

Variation of crystallinity and secondary ion quantity of uranium particles with heating temperature of Sample preparation

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$$^{circ}$$C reduced uranium secondary ion quantity to 33% compared with baking at 350$$^{circ}$$C. Uranium hydride generation ratio of the sample baked at 850$$^{circ}$$C was also 4 times higher than the sample baked at 350$$^{circ}$$C. Baking at 850$$^{circ}$$C 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 350$$^{circ}$$C is suitable for uranium particles in the safeguards sample.

Journal Articles

Preparation of the particles containing isotope reference uranium for the determination of the low abundant U isotope ratios

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 ($$^{233}$$U and $$^{236}$$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.

Journal Articles

Optimization of SIMS-APM for high enrichment uranium particles including higher uranium hydride

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

Journal Articles

Age determination analysis of a single uranium particle for safeguards

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:2 Percentile:48.75(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 $$^{230}$$Th/$$^{234}$$U ratio was measured using single-collector inductively coupled plasma mass spectrometry and a $$^{233}$$U-based reference material comprising a certain amount of $$^{229}$$Th as a progeny nuclide of $$^{233}$$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.

Journal Articles

High-spin states in $$^{35}$$S

Go, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Aoi, Nori*; Azaiez, F.*; Furutaka, Kazuyoshi; Hatsukawa, Yuichi; Kimura, Atsushi; Kisamori, Keiichi*; Kobayashi, Motoki*; et al.

Physical Review C, 103(3), p.034327_1 - 034327_8, 2021/03

 Times Cited Count:3 Percentile:63.12(Physics, Nuclear)

Journal Articles

The Impact of nuclear shape on the emergence of the neutron dripline

Tsunoda, Naofumi*; Otsuka, Takaharu; Takayanagi, Kazuo*; Shimizu, Noritaka*; Suzuki, Toshio*; Utsuno, Yutaka; Yoshida, Sota*; Ueno, Hideki*

Nature, 587, p.66 - 71, 2020/11

 Times Cited Count:26 Percentile:91.26(Multidisciplinary Sciences)

no abstracts in English

Journal Articles

Numerical simulation of liquid jet behavior in shallow pool by interface tracking method

Suzuki, Takayuki*; Yoshida, Hiroyuki; Horiguchi, Naoki; Yamamura, Sota*; Abe, Yutaka*

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 7 Pages, 2020/08

Journal Articles

Evolution of shell structure in exotic nuclei

Otsuka, Takaharu*; Gade, A.*; Sorlin, O.*; Suzuki, Toshio*; Utsuno, Yutaka

Reviews of Modern Physics, 92(1), p.015002_1 - 015002_52, 2020/03


 Times Cited Count:137 Percentile:96.45(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Experimental study of Gamow-Teller transitions via the high-energy-resolution $$^{18}$$O($$^3$$He,$$t$$)$$^{18}$$F reaction; Identification of the low-energy "super" -Gamow-Teller state

Fujita, Hirohiko*; Fujita, Yoshitaka*; Utsuno, Yutaka; Yoshida, Kenichi*; Adachi, Tatsuya*; Algora, A.*; Csatl$'o$s, M.*; Deaven, J. M.*; Estevez-Aguado, E.*; Guess, C. J.*; et al.

Physical Review C, 100(3), p.034618_1 - 034618_13, 2019/09


 Times Cited Count:10 Percentile:77.61(Physics, Nuclear)

no abstracts in English

Journal Articles

Study on optimizing microwave heating denitration method and powder characteristics of uranium trioxide

Segawa, Tomoomi; Kawaguchi, Koichi; Kato, Yoshiyuki; Ishii, Katsunori; Suzuki, Masahiro; Fujita, Shunya*; Kobayashi, Shohei*; Abe, Yutaka*; Kaneko, Akiko*; Yuasa, Tomohisa*

Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 9 Pages, 2019/05

A solution of plutonium nitrate and uranyl nitrate is converted into a mixed oxide by microwave heating denitration method. In the present study, for improving the efficiency of microwave heating and achieving high-temperature uniformity to produce homogeneous UO$$_{3}$$ powder, the microwave heating test of potassium chloride and uranyl nitrate solution, and numerical simulation analysis were conducted. The potassium chloride agar was adjusted to the dielectric loss, which is close to that of the uranyl nitrate solution and the optimum support table height was estimated to be 50 mm for denitration of the uranyl nitrate solution by microwave heating. The adiabator improved the efficiency of microwave heating denitration. Moreover, the powder yield was improved by using the adiabator owing to ease of scraping of the denitration product from the bottom of the denitration vessel.

Journal Articles

Accurate sensitive analytical technique of ultra-trace plutonium in the IAEA environmental samples

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.

Journal Articles

Radioactive strontium measurement using ICP-MS following cascade preconcentration and separation system

Takagai, Yoshitaka*; Furukawa, Makoto*; Kameo, Yutaka; Matsueda, Makoto; Suzuki, Katsuhiko*

Bunseki Kagaku, 66(4), p.223 - 231, 2017/04

 Times Cited Count:5 Percentile:21.21(Chemistry, Analytical)

no abstracts in English

Journal Articles

Analysis of plutonium isotope ratios including $$^{238}$$Pu/$$^{239}$$Pu in individual U-Pu mixed oxide particles by means of a combination of alpha spectrometry and ICP-MS

Esaka, Fumitaka; Yasuda, Kenichiro; Suzuki, Daisuke; Miyamoto, Yutaka; Magara, Masaaki

Talanta, 165, p.122 - 127, 2017/04

 Times Cited Count:13 Percentile:51.41(Chemistry, Analytical)

The isotope ratios of $$^{238}$$Pu/$$^{239}$$Pu, $$^{240}$$Pu/$$^{239}$$Pu, $$^{241}$$Pu/$$^{239}$$Pu, and $$^{242}$$Pu/$$^{239}$$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 $$^{240}$$Pu/$$^{239}$$Pu, $$^{241}$$Pu/$$^{239}$$Pu, and $$^{242}$$Pu/$$^{239}$$Pu isotope ratios with ICP-MS after particle dissolution and chemical separation of uranium, plutonium and americium with UTEVA resins. Furthermore, $$^{238}$$Pu/$$^{239}$$Pu isotope ratios were able to be calculated by using both the $$^{238}$$Pu/($$^{239}$$Pu+$$^{240}$$Pu) activity ratios that had been measured through alpha spectrometry and the $$^{240}$$Pu/$$^{239}$$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 $$^{238}$$Pu/$$^{239}$$Pu, in individual U-Pu mixed oxide particles.

Journal Articles

Determination of plutonium isotope ratios in individual uranium-plutonium mixed particles with inductively coupled plasma mass spectrometry

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:48.72(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, $$^{240}$$Pu/$$^{239}$$Pu, $$^{241}$$Pu/$$^{239}$$Pu and $$^{242}$$Pu/$$^{239}$$Pu isotope ratios were successfully determined, while it was impossible to determine $$^{238}$$Pu/$$^{239}$$Pu ratios due to the high process blank values on m/z 238.

Journal Articles

Accurate purification age determination of individual uranium-plutonium mixed particles

Miyamoto, Yutaka; Suzuki, Daisuke; Esaka, Fumitaka; Magara, Masaaki

Analytical and Bioanalytical Chemistry, 407(23), p.7165 - 7173, 2015/09

 Times Cited Count:8 Percentile:33.69(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 $$^{241}$$Am/$$^{241}$$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 $$^{241}$$Am/$$^{241}$$Pu ratio was accurately determined by spiking pure $$^{243}$$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.

Journal Articles

Precise determination of $$^{12}_{Lambda}$$C level structure by $$gamma$$-ray spectroscopy

Hosomi, Kenji; Ma, Y.*; Ajimura, Shuhei*; Aoki, Kanae*; Dairaku, Seishi*; Fu, Y.*; Fujioka, Hiroyuki*; Futatsukawa, Kenta*; Imoto, Wataru*; Kakiguchi, Yutaka*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2015(8), p.081D01_1 - 081D01_8, 2015/08

 Times Cited Count:14 Percentile:68.36(Physics, Multidisciplinary)

Level structure of the $$^{12}_{Lambda}$$C hypernucleus was precisely determined by means of $$gamma$$-ray spectroscopy. We identified four $$gamma$$-ray transitions via the $$^{12}$$C$$(pi^{+},K^{+}gamma)$$ reaction using a germanium detector array, Hyperball2. The spacing of the ground-state doublet $$(2^{-}, 1^{-}_{1})$$ was measured to be $$161.5pm0.3$$(stat)$$pm0.3$$ (syst)keV from the direct $$M1$$ transition. Excitation energies of the $$1^{-}_{2}$$ and $$1^{-}_{3}$$ states were measured to be $$2832pm3pm4$$, keV and $$6050pm8pm7$$, keV, respectively. The obtained level energies provide definitive references for the reaction spectroscopy of $$Lambda$$ hypernuclei.

Journal Articles

Superdeformation in $$^{35}$$S

Go, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Kobayashi, Motoki*; Kisamori, Keiichi*; Takaki, Motonobu*; Miya, Hiroyuki*; Ota, Shinsuke*; Michimasa, Shinichiro*; Shimoura, Susumu*; et al.

JPS Conference Proceedings (Internet), 6, p.030005_1 - 030005_4, 2015/06

Journal Articles

Development of numerical simulation for jet breakup behavior in complicated structure of BWR lower plenum, 6; Influence of the simulant molten fuel properties on jet breakup phenomenon in multi-channels

Suzuki, Takayuki; Yoshida, Hiroyuki; Abe, Yutaka*; Kaneko, Akiko*

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 7 Pages, 2015/05

In order to improve the safety of Boiling Water Reactor (BWR), it is required to know the behavior of the plant when an accident occurred. Especially, it is important to estimate the behavior of molten core jet in the lower part of the reactor pressure vessel at a severe accident. In the BWR lower plenum, the flow characteristics of molten core jet are affected by many complicated structures, such as control rod guide tubes, instrument guide tubes and core support plate. The objective of this study is to develop the simulation method for the flow characteristic of molten core jet including the effects of the complicated structures in the lower plenum based on interface tracking method code TPFIT (Two Phase Flow simulation code with Interface Tracking). To verify and validate the applicability of the developed method in detail, it is necessary to obtain the experimental data that can be compared with detailed numerical results by the TPFIT. Therefore, experimental works by use of multi-phase flow visualization technique were also carried out. In the experiments, time series of interface shapes are observed by high speed camera and velocity profiles in/out of the jet were measured by the PIV method. In this paper, we carried out a numerical simulation of the jet breakup phenomena in the multi-channels with various simulant molten materials to evaluate the influence of properties on the jet breakup phenomena. As a result, it was confirmed that density and surface tension affected on the falling down velocity of the simulant materials and the interface behavior of the molten jet. However, viscosities of the simulant materials have small effects on jet breakup phenomena, including the interface shape and size of fragments.

JAEA Reports

Model development of light water reactor fuel analysis code RANNS for reactivity-initiated accident conditions

Udagawa, Yutaka; Suzuki, Motoe; Amaya, Masaki

JAEA-Data/Code 2014-025, 27 Pages, 2015/02


A light water reactor fuel analysis code RANNS has been developed to analyze thermal and mechanical behaviors of a single fuel rod in mainly reactivity-initiated accident (RIA) conditions. The recent model development for the RANNS code has been focused on improving predictability of stress, strain, and temperature inside a fuel rod during pellet cladding mechanical interaction (PCMI), which is one of the most important behaviors of high-burnup fuels under RIA conditions. This report provides descriptions of the models developed and/or validated recently via experimental analyses using the RANNS code on the RIA-simulating experiments conducted in the nuclear safety research reactor (NSRR): models for mechanical behaviors as relocation of fuel pellets, pellet yielding, pellet-cladding mechanical bonding, and PCMI failure limit of fuel cladding, and thermal behaviors as pellet-cladding gap conductance and heat transfer from fuel rod surface to coolant water.

Journal Articles

Direct isotope ratio analysis of individual uranium-plutonium mixed particles with various U/Pu ratios by thermal ionization mass spectrometry

Suzuki, Daisuke; Esaka, Fumitaka; Miyamoto, Yutaka; Magara, Masaaki

Applied Radiation and Isotopes, 96, p.52 - 56, 2015/02

 Times Cited Count:15 Percentile:80.05(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%$$^{235}$$U enriched, NBL) and SRM 947 (NBS) solutions. As a result of isotope ratio analysis, accurate values for U and Pu ratios, except for $$^{238}$$Pu/$$^{239}$$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 $$^{238}$$Pu/$$^{239}$$Pu isotope analysis, it was shown that this analytical technique has a potential of powerful tool for nuclear safeguards and forensics.

349 (Records 1-20 displayed on this page)