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Journal Articles

The Effects of plutonium content and self-irradiation on thermal conductivity of mixed oxide fuel

Ikusawa, Yoshihisa; Morimoto, Kyoichi; Kato, Masato; Saito, Kosuke; Uno, Masayoshi*

Nuclear Technology, 205(3), p.474 - 485, 2019/03

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

This study evaluated the effects of plutonium content and self-irradiation on the thermal conductivity of mixed-oxide (MOX) fuel. Samples of UO$$_{2}$$ fuel and various MOX fuels were tested. The MOX fuels had a range of plutonium contents, and some samples were stored for 20 years. The thermal conductivity of these samples was determined from thermal diffusivity measurements taken via laser flash analysis. Although the thermal conductivity decreased with increasing plutonium content, this effect was slight. The effect of self-irradiation was investigated using the stored samples. The reduction in thermal conductivity caused by self-irradiation depended on the plutonium content, its isotopic composition, and storage time. The reduction in thermal conductivity over 20 years' storage can be predicted from the change of lattice parameter. In addition, the decrease in thermal conductivity caused by self-irradiation was recovered with heat treatment, and recovered almost completely at temperatures over 1200 K. From these evaluation results, we formulated an equation for thermal conductivity that is based on the classical phonon-transport model. This equation can predict the thermal conductivity of MOX fuel thermal conductivity by accounting for the influences of plutonium content and self-irradiation.

Journal Articles

Rapid separation of zirconium using microvolume anion-exchange cartridge for $$^{93}$$Zr determination with isotope dilution ICP-MS

Asai, 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:4 Percentile:70.28(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 $$^{93}$$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$$^{3}$$. 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 $$^{93}$$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.

Journal Articles

${it In-situ}$ observation of dislocation evolution in ferritic and austenitic stainless steels under tensile deformation by using neutron diffraction

Sato, Shigeo*; Kuroda, Asumi*; Sato, Kozue*; Kumagai, Masayoshi*; Harjo, S.; Tomota, Yo*; Saito, Yoichi*; Todoroki, Hidekazu*; Onuki, Yusuke*; Suzuki, Shigeru*

Tetsu To Hagane, 104(4), p.201 - 207, 2018/00

 Times Cited Count:3 Percentile:58.46(Metallurgy & Metallurgical Engineering)

Journal Articles

Recovery of rare metals using nucleic acid bases and extractants immobilized by grafted polymer chains

Saito, Kyoichi*; Asai, Shiho

Bunseki Kagaku, 66(11), p.771 - 782, 2017/11

Recovery and purification of rare metals, which are essential ingredients for highly functional materials, generally comes with operational difficulty. In this study, we have developed polymer adsorbents specially designed for highly-efficient adsorption of rare metal ions and exhibited their practical adsorption performances. Radiation-induced graft polymerization, one of the effective modification techniques for polymers, was employed for preparing the proposed adsorbents. Among such adsorbents, a 6-nylon fiber with nucleic-acid base, adenine, on the surface of the fiber demonstrated specific adsorption of ruthenium and palladium ions. In addition, a 6-nylon fiber with an extractant HDEHP (bis (2-ethylhexyl) phophoric acid) that has high affinity for lanthanides, achieved higher separation speed than a commercially available HDEHP-impregnated resin.

Journal Articles

Preparation of solid phase extraction cartridges for trace analysis of radionuclides

Asai, Shiho; Saito, Kyoichi*

Biomedical Research on Trace Elements, 28(1), p.1 - 10, 2017/04

Radionuclides are commonly determined with radiometry and mass spectrometry. For $$gamma$$-emitting nuclides, the activities can be measured without chemical separation due to the strong penetration ability. In contrast, the measurements of alpha and beta-emitting nuclides are generally associated with tedious and time-consuming chemical separation procedures to remove concomitants. Thus, an adsorbent that achieves rapid separation is desirable to reduce separation time and workload. Our research team has developed compact cartridge-type solid phase extraction materials which enable to facilitate separation procedures. In this review, basic separation performances of the developed cartridges were overviewed along with two application examples to radionuclide-containing samples.

Journal Articles

Removal of radioactive substances using inorganic compounds entangled by polymer chain grafted onto fiber

Saito, Kyoichi*; Kojima, Takashi*; Asai, Shiho

Bunseki Kagaku, 66(4), p.233 - 242, 2017/04

 Times Cited Count:1 Percentile:93.04(Chemistry, Analytical)

Insoluble cobalt ferrocyanide and sodium titanate specifically capture cesium and strontium ions, respectively, in water contaminated with radionuclides which is found in Fukushima Daiichi NPP. The inorganic compounds used in this study were formed as precipitates in the polymer chain grafted onto a commercially available 6-nylon fiber using radiation-induced graft polymerization. An impregnation structure with the precipitates entangled by the grafted polymer chain through an electrostatic interaction via multipoints was indicated. The resultant insoluble cobalt ferrocyanide- or sodium titanate-impregnated fiber exhibited a higher adsorption rate and adsorption capacity per gram of the inorganic compound for cesium or strontium ions in seawater than conventional granular adsorbents.

Journal Articles

Preparation of Sr adsorptive fiber by impregnating with crown ether derivative for $$^{90}$$Sr measurement

Horita, Takuma; Asai, Shiho; Konda, Miki; Hanzawa, Yukiko; Saito, Kyoichi*; Fujiwara, Kunio*; Sugo, Takanobu*; Kitatsuji, Yoshihiro

Bunseki Kagaku, 66(3), p.189 - 193, 2017/03

 Times Cited Count:0 Percentile:100(Chemistry, Analytical)

A Sr-selective adsorption fiber was prepared for rapid analysis of $$^{90}$$Sr content by using radiation-induced emulsion graft polymerization and subsequent chemical modification. A polyethylene fiber with a diameter of 13 $$mu$$m was first immersed in a methanol solution of an epoxy-group-containing vinyl monomer, glycidyl methacrylate (GMA), and polyoxyethylene sorbitol ester (Tween20) as a surfactant for graft-polymerization of GMA. Octadecylamine was then bound to a polymer chain extending from the fiber surface providing hydrophobicity to the polymer chain. Dicyclohexano-18-crown-6 (DCH18C6) was finally impregnated onto the polymer chain via a hydrophobic interaction between the octadecyl moiety of the polymer chain and the cyclohexyl moiety of DCH18C6. The fiber surface structure, characterized by DCH18C6 molecules loosely entangled with polymer chains, afforded realizes the rapid and selective adsorption of Sr ions with an adsorption rate approximately 100 times higher than that of a commercially available Sr-selective resin (Sr Resin).

Journal Articles

Studies of high density baryon matter with high intensity heavy-ion beams at J-PARC

Sako, Hiroyuki; Harada, Hiroyuki; Sakaguchi, Takao*; Chujo, Tatsuya*; Esumi, Shinichi*; Gunji, Taku*; Hasegawa, Shoichi; Hwang, S.; Ichikawa, Yudai; Imai, Kenichi; et al.

Nuclear Physics A, 956, p.850 - 853, 2016/12

 Times Cited Count:10 Percentile:26.66(Physics, Nuclear)

Journal Articles

Rapid measurement scheme for texture in cubic metallic materials using time-of-flight neutron diffraction at iMATERIA

Onuki, Yusuke*; Hoshikawa, Akinori*; Sato, Shigeo*; Xu, P. G.; Ishigaki, Toru*; Saito, Yoichi*; Todoroki, Hidekazu*; Hayashi, Makoto*

Journal of Applied Crystallography, 49(5), p.1579 - 1584, 2016/10


 Times Cited Count:17 Percentile:15.51(Chemistry, Multidisciplinary)

Journal Articles

Universal scaling for the spin-electricity conversion on surface states of topological insulators

Yamamoto, Keita*; Shiomi, Yuki*; Segawa, Koji*; Ando, Yoichi*; Saito, Eiji

Physical Review B, 94(2), p.024404_1 - 024401_6, 2016/05

 Times Cited Count:9 Percentile:43.52(Materials Science, Multidisciplinary)

We have investigated spin-electricity conversion on surface states of bulk-insulating topological insulator (TI) materials using a spin-pumping technique. The sample structure is Ni-Fe/Cu/TI trilayers, in which magnetic proximity effects on the TI surfaces are negligibly small owing to the inserted Cu layer. Voltage signals produced by the spin-electricity conversion are clearly observed and are enhanced with decreasing temperature, in line with the dominant surface transport at lower temperatures. The efficiency of the spin-electricity conversion is greater for TI samples with a higher resistivity of bulk states and longer mean free path of surface states, consistent with the surface spin-electricity conversion.

Journal Articles

Preparation of microvolume anion-exchange cartridge for inductively coupled plasma mass spectrometry-based determination of $$^{237}$$Np content in spent nuclear fuel

Asai, 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:7 Percentile:58.63(Chemistry, Analytical)

Neptunium-237 ($$^{237}$$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 $$^{237}$$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 $$^{237}$$ Np with ICP-MS. Disks with a volume of 0.08 cm$$^{3}$$ 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 $$^{237}$$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%.

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.

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

no abstracts in English

Journal Articles

Removal of cesium ions from contaminated seawater in closed area using adsorptive fiber

Someya, Takaaki*; Asai, Shiho; Fujiwara, Kunio*; Sugo, Takanobu*; Umeno, Daisuke*; Saito, Kyoichi*

Nippon Kaisui Gakkai-Shi, 69(1), p.42 - 48, 2015/02

A large amount of seriously contaminated sea water with radioactive Cs has been reserved in semi-enclosed coastal sea area which is separated by silt fences and embankments. Insoluble cobalt ferrocyanide (Co-FC) microparticles-impregnated fiber was developed for removing Cs from the contaminated sea water. The resultant Co-FC-impregnated fiber was immersed in either nonradioactive or radioactive Cs solution. The adsorption isotherm well correlated with a Langmuir-type equation. In addition, mass-transfer capacity coefficients were determined by fitting the experimental data of the rate of Cs adsorption onto the Co-FC-impregnated fiber to theoretical adsorption curves based on the Cs concentration difference between the bulk and the interface in seawater as a driving force of the overall adsorption rate. Decontamination factors as functions of fiber weight and the contact time required for the removal of cesium ions from the contaminated seawater in a closed area were estimated.

Journal Articles

Spin-electricity conversion induced by spin injection into topological insulators

Shiomi, Yuki*; Nomura, Kentaro*; Kajiwara, Yosuke*; Eto, Kazuma*; Novak, M.*; Segawa, Koji*; Ando, Yoichi*; Saito, Eiji

Physical Review Letters, 113(19), p.196601_1 - 196601_5, 2014/11

 Times Cited Count:185 Percentile:0.92(Physics, Multidisciplinary)

Journal Articles

Simple method for high-density impregnation of Aliquat 336 onto porous sheet and binding performance of resulting sheet for palladium ions

Tanaka, Ryota*; Ishihara, Ryo*; Miyoshi, Kazuyoshi*; Umeno, Daisuke*; Saito, Kyoichi*; Asai, Shiho; Yamada, Shinsuke*; Hirota, Hideyuki*

Separation Science and Technology, 49(1), p.154 - 159, 2014/01

 Times Cited Count:4 Percentile:78.5(Chemistry, Multidisciplinary)

Journal Articles

Determination of mole percentages of brush and root of polymer chain grafted onto porous sheet

Uchiyama, Shoichiro*; Ishihara, Ryo*; Umeno, Daisuke*; Saito, Kyoichi*; Yamada, Shinsuke*; Hirota, Hideyuki*; Asai, Shiho

Journal of Chemical Engineering of Japan, 46(6), p.414 - 419, 2013/06

 Times Cited Count:7 Percentile:66.47(Engineering, Chemical)

Journal Articles

Crosslinked-chelating porous sheet with high dynamic binding capacity of metal ions

Wada, Go*; Ishihara, Ryo*; Miyoshi, Kazuyoshi*; Umeno, Daisuke*; Saito, Kyoichi*; Asai, Shiho; Yamada, Shinsuke*; Hirota, Hideyuki*

Solvent Extraction and Ion Exchange, 31(2), p.210 - 220, 2013/02

 Times Cited Count:2 Percentile:84.96(Chemistry, Multidisciplinary)

A crosslinked chelating porous sheet was prepared by cografting ethylene glycol dimethacrylate (EGDMA) with glycidyl methacrylate onto an electron-beam-irradiated porous polyethylene sheet, followed by the introduction of an iminodiacetate group. At a molar percentage of EGDMA of 1.0 mol%, the sheet exhibited a maximum dynamic binding capacity for copper ions of 0.93 mmol/g, while the equilibrium binding capacity remained the same (1.2 mmol/g) as that of a non-crosslinked chelating porous sheet. The crosslinking of the grafted chain causes copper ions to lower their diffusion rate along the sheet thickness driven by the gradient of the amount of copper ions adsorbed.

JAEA Reports

Inspection and repair techniques in the reactor vessel of the experimental fast reactor Joyo; Observation technical development in a reactor vessel of the fast reactor

Imaizumi, Kazuyuki; Saito, Takakazu; Tobita, Shigeharu; Nagai, Akinori; Kitamura, Ryoichi; Okazaki, Yoshihiro

JAEA-Technology 2012-027, 49 Pages, 2012/08


In-Vessel Observations (IVO) techniques for Sodium cooled Fast Reactors (SFRs) are important in confirming its safety and integrity. In order to secure the reliability of IVO techniques, it was necessary to demonstrate the performance under the actual reactor environment with high temperature, high radiation dose and remained sodium. During the investigation of an incident occurred in Joyo, the following observation systems were specifically developed for Joyo. And the following two observations were conducted. (1) Simple overhead observation using a standard video camera for the top of the sub-assemblies and the in-vessel storage rack (2) Narrow space observation using remote handling device equipped with radiation-resistant fiberscope for the bottom face of the upper core structure. As a result, the observations under the actual reactor environment were successfully made even in the narrow space in the reactor vessel and the results provided useful information on incident investigations and planning of restoration work.

Journal Articles

Dependence of lanthanide-ion binding performance on HDEHP concentration in HDEHP impregnation to porous sheet

Ishihara, Ryo*; Asai, Shiho; Otosaka, Shigeyoshi; Yamada, Shinsuke*; Hirota, Hideyuki*; Miyoshi, Kazuyoshi*; Umeno, Daisuke*; Saito, Kyoichi*

Solvent Extraction and Ion Exchange, 30(2), p.171 - 180, 2012/02

 Times Cited Count:6 Percentile:69.88(Chemistry, Multidisciplinary)

Journal Articles

Removal of cesium using cobalt-ferrocyanide-impregnated polymer-chain-grafted fibers

Ishihara, Ryo*; Fujiwara, Kunio*; Harayama, Takato*; Okamura, Yusuke*; Uchiyama, Shoichiro*; Sugiyama, Mai*; Someya, Takaaki*; Amakai, Wataru*; Umino, Satoshi*; Ono, Tsubasa*; et al.

Journal of Nuclear Science and Technology, 48(10), p.1281 - 1284, 2011/10


 Times Cited Count:37 Percentile:4.19(Nuclear Science & Technology)

110 (Records 1-20 displayed on this page)