Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 130

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Study on chemical interaction between UO$$_{2}$$ and Zr at precisely controlled high temperatures

Shirasu, Noriko; Sato, Takumi; Suzuki, Akihiro*; Nagae, Yuji; Kurata, Masaki

Journal of Nuclear Science and Technology, 60(6), p.697 - 714, 2023/06

 Times Cited Count:1 Percentile:63.33(Nuclear Science & Technology)

Interaction tests between UO$$_{2}$$ and Zr were performed at precisely controlled high temperatures between 1840 and 2000 $$^{circ}$$C to understand the interaction mechanism in detail. A Zr rod was inserted in a UO$$_{2}$$ crucible and then heat-treated at a fixed temperature in Ar-gas flow for 10 min. After heating in the range of 1890 to 1930 $$^{circ}$$C, the Zr rod was deformed to a round shape, in which the post-analysis detected the significant diffusion of U into the Zr region and the formation of a dominant $$alpha$$-Zr(O) matrix and a small amount of U-Zr-O precipitates. The abrupt progress of liquefaction was observed in the sample heated at around 1940 $$^{circ}$$C or higher. The higher oxygen concentration in the $$alpha$$-Zr(O) matrix suppressed the liquefaction progress, due to the variation in the equilibrium state. The U-Zr-O melt formation progressed by the selective dissolution of Zr from the matrix, and the selective diffusion of U could occur via the U-Zr-O melt.

Journal Articles

Outlining zircon growth in a granitic pluton using 3D cathodoluminescence patterns, U-Pb age, titanium concentration, and Th/U; Implications for the magma chamber process of Okueyama granite, Kyushu, Japan

Yuguchi, Takashi*; Ito, Daichi*; Yokoyama, Tatsunori; Sakata, Shuhei*; Suzuki, Satoshi*; Ogita, Yasuhiro; Yagi, Koshi*; Imura, Takumi*; Motai, Satoko*; Ono, Takeshi*

Lithos, 440-441, p.107026_1 - 107026_14, 2023/03

 Times Cited Count:0 Percentile:0.02(Geochemistry & Geophysics)

We propose a new method for elucidating zircon growth in granitic plutons, based on variations in three-dimensional 3D cathodoluminescence (CL) patterns, U-Pb ages, titanium concentration, and Th/U ratios. We focused on the zircon growth processes in the Okueyama granite (OKG) in central Kyushu, Japan, to obtain interpretations of magma chamber processes that result in the formation of granitic plutons. The OKG consists of three lithofacies: biotite granite (BG), hornblende granite (HG), and hornblende granodiorite (HGD). To determine the 3D internal structure and growth pattern of a zircon crystal, we performed CL observations for multi-sections of the samples. Simultaneously, we also determined the zircon U-Pb age and titanium concentration of the center sections of the samples. The 3D distribution of the oscillatory zoning can be used to determine the crystal nucleus. The simultaneous determination of zircon U-Pb ages and Ti concentrations of the granite samples indicates the time-temperature (t-T) history of granitic magma before its solidification. The t-T histories of the BG, HG, and HGD represented similar cooling behaviors within the magma chamber: rapid cooling from the zircon crystallization temperature to the closure temperature of the biotite K-Ar system between 16 Ma and 10 Ma. The variations in the Th/U ratios against temperature also demonstrate a different trend at the boundary of approximately 670 $$^{circ}$$C. Fractional crystallization in the magma chamber progressed significantly at temperatures above 670 $$^{circ}$$C; below 670 $$^{circ}$$C, crystallization progressed slowly, indicating only minimal changes in the magma composition. The variations in the Th/U ratio against temperature in the BG, HG, and HGD portrayed common tendencies, indicating the same behavior in the progression of fractional crystallization among the three lithofacies, which in turn, represented the same behavior within the entire magma chamber.

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

Simultaneous determination of zircon crystallisation age and temperature; Common thermal evolution of mafic magmatic enclaves and host granites in the Kurobegawa granite, central Japan

Yuguchi, Takashi*; Yamazaki, Hayato*; Ishibashi, Kozue*; Sakata, Shuhei*; Yokoyama, Tatsunori; Suzuki, Satoshi*; Ogita, Yasuhiro; Sando, Kazusa*; Imura, Takumi*; Ono, Takeshi*

Journal of Asian Earth Sciences, 226, p.105075_1 - 105075_9, 2022/04

 Times Cited Count:4 Percentile:54.83(Geosciences, Multidisciplinary)

Simultaneous determination of the U-Pb age of zircon and concentration of titanium in a single analysis spot, using inductively coupled plasma mass spectrometry with laser ablation sample introduction, produces paired age and temperature data of zircon crystallisation, potentially revealing time-temperature ($$t-T$$) histories for evolved magma. The Kurobegawa granite, central Japan, contains abundant mafic magmatic enclaves (MMEs). We applied this method to evaluate MMEs and their host (enclosing) granites. Cooling behaviour common to both MMEs and host rocks was found between 1.5 and 0.5 Ma. Rapid cooling from the zircon crystallisation temperature to the closure temperature of biotite K-Ar system was within $$sim$$1 million year. Combining the obtained $$t-T$$ paths of MMEs and host rocks with petrological information can provide insights into magma chamber processes. This suggests that MME flotation, migration, and spread through the magma chamber ceased at 1.5-0.5 Ma, indicating the emplacement age of the Kurobegawa granitic pluton, as no large-scale reheating episodes have occurred since then.

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

Radioactivity and radionuclides in deciduous teeth formed before the Fukushima-Daiichi Nuclear Power Plant accident

Takahashi, Atsushi*; Chiba, Mirei*; Tanahara, Akira*; Aida, Jun*; Shimizu, Yoshinaka*; Suzuki, Toshihiko*; Murakami, Shinobu*; Koarai, Kazuma; Ono, Takumi*; Oka, Toshitaka; et al.

Scientific Reports (Internet), 11(1), p.10355_1 - 10355_11, 2021/05

 Times Cited Count:6 Percentile:38.85(Multidisciplinary Sciences)

Journal Articles

Microparticles with diverse sizes and morphologies from mechanical and laser cutting of fuel debris simulants and geopolymer as a covering material

Zhou, Q.*; Saito, Takumi*; Suzuki, Seiya; Yano, Kimihiko; Suzuki, Shunichi*

Journal of Nuclear Science and Technology, 58(4), p.461 - 472, 2021/04

 Times Cited Count:6 Percentile:69.63(Nuclear Science & Technology)

Journal Articles

Morphological reproductive characteristics of testes and fertilization capacity of cryopreserved sperm after the Fukushima accident in raccoon (${it Procyon lotor}$)

Komatsu, Kazuki*; Iwasaki, Tsugumi*; Murata, Kosuke*; Yamashiro, Hideaki*; Goh, V. S. T.*; Nakayama, Ryo*; Fujishima, Yohei*; Ono, Takumi*; Kino, Yasushi*; Shimizu, Yoshinaka*; et al.

Reproduction in Domestic Animals, 56(3), p.484 - 497, 2021/03

 Times Cited Count:9 Percentile:85.28(Agriculture, Dairy & Animal Science)

We have established an archive system of livestock and wild animals from the surrounding ex-evacuation zone. Wildlife within the alert zone have been exposed to low-dose-rate (LDR) radiation for a long and continuous time. In this study, we analysed the morphological characteristics of the testes and in vitro fertilization (IVF) capacity of cryopreserved sperm of raccoons from the ex-evacuation zone of the FDNPP accident. This study revealed that the chronic and LDR radiation exposure associated with the FDNPP accident had no adverse effect on the reproductive characteristics and functions of male raccoons.

JAEA Reports

Technical design of the pressure-resistant chamber for open inspections of the storage containers of nuclear fuel materials

Marufuji, Takato; Sato, Takumi; Ito, Hideaki; Suzuki, Hisashi; Fujishima, Tadatsune; Nakano, Tomoyuki

JAEA-Technology 2019-006, 22 Pages, 2019/05

JAEA-Technology-2019-006.pdf:2.84MB

Radioactive contamination incident occurred at Plutonium Fuel Research Facility (PFRF) in Oarai Research and Development Institute, Japan Atomic Energy Agency on June 6, 2017. During inspection work of storage container containing nuclear fuel materials, the PVC bag packaging in the storage container ruptured when a worker opened the lid in the hood, and a part of contents was spattered over the room. The cause of the increase of internal pressure of the storage container was gas generation by alpha radiolysis of the epoxy resin mixed with nuclear fuel materials. Opening inspection of about 70 similar containers stored in PFRF has been planned to confirm the condition of the contents and to stabilize the stored materials containing organic compounds. For safe and reliable open inspection of the storage containers with high internal pressure in the glove box, it is necessary to develop a pressure-resistant chamber in which the storage containers are opened and the contents are inspected under gastight condition. This report summarizes the concerns and countermeasures of the chamber design and the design results of the chamber.

Journal Articles

Application of automated particle screening for effective analysis of individual uranium particles by thermal ionization mass spectrometry

Esaka, Fumitaka; Suzuki, Daisuke; Yomogida, Takumi; Magara, Masaaki

Analytical Methods, 8(7), p.1543 - 1548, 2016/02

AA2015-0572.pdf:0.66MB

 Times Cited Count:8 Percentile:50.09(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.

Journal Articles

2016 Professional Engineer (PE) test preparation course "Nuclear and Radiation Technical Disciplines"

Takahashi, Naoki; Yoshinaka, Kazuyuki; Harada, Akio; Yamanaka, Atsushi; Ueno, Takashi; Kurihara, Ryoichi; Suzuki, Soju; Takamatsu, Misao; Maeda, Shigetaka; Iseki, Atsushi; et al.

Nihon Genshiryoku Gakkai Homu Peji (Internet), 64 Pages, 2016/00

no abstracts in English

Journal Articles

Growth of single-phase nanostructured Er$$_2$$O$$_3$$ thin films on Si (100) by ion beam sputter deposition

Mao, W.*; Fujita, Masaya*; Chikada, Takumi*; Yamaguchi, Kenji; Suzuki, Akihiro*; Terai, Takayuki*; Matsuzaki, Hiroyuki*

Surface & Coatings Technology, 283, p.241 - 246, 2015/12

 Times Cited Count:3 Percentile:13.74(Materials Science, Coatings & Films)

Single-phase nanocrystalline thin films of Er$$_2$$O$$_3$$ (440) has been first prepared using Si (100) substrates by ion beam sputter deposition at 973 K at a pressure of $$<$$ 10$$^{-5}$$ Pa and $${it in}$$-$${it situ}$$ annealing at 1023 K at a pressure of $$approx$$ 10$$^{-7}$$ Pa. Er silicides formed during the deposition are eliminated via the annealing, which results in the single phase and the smooth surface of the Er$$_2$$O$$_3$$ thin films. The epitaxial relationship between Si (100) and Er$$_2$$O$$_3$$ (110) is clarified by X-ray diffraction and reflection high energy electron diffraction.

Journal Articles

R&D activities of tritium technologies on Broader Approach in Phase 2-2

Isobe, Kanetsugu; Kawamura, Yoshinori; Iwai, Yasunori; Oyaizu, Makoto; Nakamura, Hirofumi; Suzuki, Takumi; Yamada, Masayuki; Edao, Yuki; Kurata, Rie; Hayashi, Takumi; et al.

Fusion Engineering and Design, 98-99, p.1792 - 1795, 2015/10

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Activities on Broader Approach (BA) were started in 2007 on the basis of the Agreement between the Government of Japan and the EURATOM. The period of BA activities consist of Phase1 and Phase2 dividing into Phase 2-1 (2010-2011), Phase 2-2 (2012-2013) and Phase 2-3 (2014-2016). Tritium technology was chosen as one of important R&D issues to develop DEMO plant. R&D activities of tritium technology on BA consist of four tasks. Task-1 is to prepare and maintain the tritium handling facility in Rokkasho BA site in Japan. Task 2, 3 and 4 are main R&D activities for tritium and these are focused on: Task-2) Development of tritium accountancy technology, Task-3) Development of basic tritium safety research, Task-4) Tritium durability test. R&D activities of tritium technology in Phase 2-2 were underway successfully and closed in 2013.

Journal Articles

SiC coating as hydrogen permeation reduction and oxidation resistance for nuclear fuel cladding

Usui, Takahiro*; Sawada, Akihiko; Amaya, Masaki; Suzuki, Akihiro*; Chikada, Takumi*; Terai, Takayuki*

Journal of Nuclear Science and Technology, 52(10), p.1318 - 1322, 2015/10

 Times Cited Count:48 Percentile:97.23(Nuclear Science & Technology)

SiC coating is one of countermeasures for the prevention of oxidation and hydrogen embrittlement of fuel claddings because SiC has high resistance of oxidation and hydrogen permeation. Hydrogen permeation and oxidation experiments for the cladding materials with SiC coatings were conducted in unirradiated conditions. The sputtering method was employed to make SiC coatings. In the hydrogen permeation experiment, SUS316 was used as a base material of the coating. SUS316 with SiC coatings showed hydrogen permeation reduction by one order of magnitude. In the oxidation experiments, Zry-4 and SUS316 were used as base materials of the coatings. The weight gain of the Zry-4 specimens with a SiC coating decreased by about one-fifth compared to the uncoated ones. This phenomenon was observed for SUS316 at 750 $$^{circ}$$C as well. The peel-off of the coating was observed in some experiments, and it is considered that the peel-off was caused by the difference of the thermal expansions between coatings and base materials. Thicker coatings showed better oxidation resistance, but thinner coatings showed more tolerance of peel-off.

Journal Articles

Temperature of thermal spikes in amorphous silicon nitride films produced by 1.11 MeV C$$_{60}^{3+}$$ impacts

Kitayama, Takumi*; Nakajima, Kaoru*; Suzuki, Motofumi*; Narumi, Kazumasa; Saito, Yuichi; Matsuda, Makoto; Sataka, Masao*; Tsujimoto, Masahiko*; Isoda, Shoji*; Kimura, Kenji*

Nuclear Instruments and Methods in Physics Research B, 354, p.183 - 186, 2015/07

 Times Cited Count:2 Percentile:17.42(Instruments & Instrumentation)

Journal Articles

Recent progress on tritium technology research and development for a fusion reactor in Japan Atomic Energy Agency

Hayashi, Takumi; Nakamura, Hirofumi; Kawamura, Yoshinori; Iwai, Yasunori; Isobe, Kanetsugu; Yamada, Masayuki; Suzuki, Takumi; Kurata, Rie; Oyaizu, Makoto; Edao, Yuki; et al.

Fusion Science and Technology, 67(2), p.365 - 370, 2015/03

 Times Cited Count:1 Percentile:9.61(Nuclear Science & Technology)

Journal Articles

R&D status on water cooled ceramic breeder blanket technology

Enoeda, Mikio; Tanigawa, Hisashi; Hirose, Takanori; Nakajima, Motoki; Sato, Satoshi; Ochiai, Kentaro; Konno, Chikara; Kawamura, Yoshinori; Hayashi, Takumi; Yamanishi, Toshihiko; et al.

Fusion Engineering and Design, 89(7-8), p.1131 - 1136, 2014/10

 Times Cited Count:21 Percentile:83.69(Nuclear Science & Technology)

The development of a Water Cooled Ceramic Breeder (WCCB) Test Blanket Module (TBM) is being performed as one of the most important steps toward DEMO blanket in Japan. Regarding the fabrication technology development using F82H, the fabrication of a real scale mockup of the back wall of TBM was completed. Also the assembling of the complete box structure of the TBM mockup and planning of the pressurization testing was studied. The development of advanced breeder and multiplier pebbles for higher chemical stability was performed for future DEMO blanket application. From the view point of TBM test result evaluation and DEMO blanket performance design, the development of the blanket tritium simulation technology, investigation of the TBM neutronics measurement technology and the evaluation of tritium production and recovery test using D-T neutron in the Fusion Neutronics Source (FNS) facility has been performed.

Journal Articles

Sputtering of SiN films by 540 keV C$$_{60}$$$$^{2+}$$ ions observed using high-resolution Rutherford backscattering spectroscopy

Nakajima, Kaoru*; Morita, Yosuke*; Kitayama, Takumi*; Suzuki, Motofumi*; Narumi, Kazumasa; Saito, Yuichi; Tsujimoto, Masahiko*; Isoda, Shoji*; Fujii, Yoshikazu*; Kimura, Kenji*

Nuclear Instruments and Methods in Physics Research B, 332, p.117 - 121, 2014/08

 Times Cited Count:7 Percentile:48.01(Instruments & Instrumentation)

Journal Articles

Adsorption of H atoms on cubic Er$$_2$$O$$_3$$ (001) surface; A DFT study

Mao, W.*; Chikada, Takumi*; Shimura, Kenichiro*; Suzuki, Akihiro*; Yamaguchi, Kenji; Terai, Takayuki*

Journal of Nuclear Materials, 443(1-3), p.555 - 561, 2013/11

 Times Cited Count:3 Percentile:25.48(Materials Science, Multidisciplinary)

In this work, ${it ab initio}$ calculations based on density functional theory (DFT) and generalized gradient approximation were performed to investigate the structural and electronic properties of the cubic Er$$_{2}$$O$$_{3}$$ (001) surface and H adsorption processes on this surface. Several stable adsorption sites were identified, and at the most energetically favorable adsorption sites it was found that H bonds with O atoms at the cubic Er$$_{2}$$O$$_{3}$$ (001) surface with an adsorption energy of 295.68 kJ mol$$^{-1}$$ at coverage 1/8 ML, which was inclined to decrease with the increase of H coverage ($$>$$ 1/4 ML). In addition, the calculations revealed that the dissociative H atom configurations have adsorption energies that are at least 152.64 kJ mol$$^{-1}$$ greater than the H$$_2$$ molecule configurations on the surface. These results are discussed in regard of the hydrogen isotope permeation behavior in the tritium permeation barrier in a fusion reactor.

Journal Articles

Size and elemental analyses of nano colloids in deep granitic groundwater; Implications for transport of trace elements

Saito, Takumi*; Suzuki, Yohei*; Mizuno, Takashi

Colloids and Surfaces A; Physicochemical and Engineering Aspects, 435(Sp.IAP2012), p.48 - 55, 2013/10

 Times Cited Count:20 Percentile:46.72(Chemistry, Physical)

Nano colloids in granitic groundwater obtained from a borehole located at the -300-m stage of the Mizunami Underground Research Laboratory were studied in terms of their size distributions by flow-field flow fractionation. In order to deal with relatively low concentrations of colloids, colloids were enriched first by ultrafiltration, and then by in-situ enrichment using a large injection loop and the slot flow technique. The size distributions of organic and inorganic constituents of colloids were measured by UV/Vis, fluorescence and inductively coupled plasma mass spectrometry, from which possible association of trace elements with host colloidal phases consisting of major elements and organic materials was discussed. Trace elements, namely, Sr, lanthanides (La, Ce, Eu, Lu), actinide elements (U, Th) and heavy metals (Cu, Zn and W), exhibited distinct size distributions, reflecting their preferential association with certain host colloidal phases.

130 (Records 1-20 displayed on this page)