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Journal Articles

Radiocesium in Shiitake mushroom; Accumulation in living fruit bodies and leaching from dead fruit bodies

Guido-Garcia, F.; Sakamoto, Fuminori; David, K.*; Kozai, Naofumi; Grambow, B.

Chemosphere, 279, p.130511_1 - 130511_10, 2021/09

 Times Cited Count:0 Percentile:0(Environmental Sciences)

Cesium (Cs) accumulation by Shiitake was investigated to contribute to the elucidation of radiocesium-cycling mechanisms in forest environments. The results demonstrate that Shiitake non-specifically accumulates Cs while accumulating the essential element K and provide evidence that no selective Cs accumulation (or binding) sites exist within the Shiitake fruit body. Furthermore, the present results show that most accumulated Cs quickly leaches out from the dead fruit body with exposure to water. The leached Cs was largely adsorbable on clay minerals, suggesting that the Shiitake fruit body likely contains Cs in the cation form.

Journal Articles

Mechanical failure of high-burnup fuel rods with stress-relieved annealed and recrystallized M-MDA cladding under reactivity-initiated accident conditions

Mihara, Takeshi; Udagawa, Yutaka; Sugiyama, Tomoyuki; Amaya, Masaki

Journal of Nuclear Science and Technology, 58(8), p.872 - 885, 2021/08

 Times Cited Count:0 Percentile:0.02(Nuclear Science & Technology)

Journal Articles

Thermal-neutron capture cross-section measurement of $$^{237}$$Np using graphite thermal column

Nakamura, Shoji; Endo, Shunsuke; Kimura, Atsushi; Shibahara, Yuji*

KURNS Progress Report 2020, P. 94, 2021/08

The present study selected $$^{237}$$Np among radioactive nuclides and aimed to converge a contradiction between reported thermal-neutron capture cross sections. Neutron irradiation was carried out using the graphite thermal column equipped with the Kyoto University Research Reactor. A solution equivalent to 950 Bq order of radioactivity was pipetted out of a $$^{237}$$Np standard solution and dropped onto a fiber filter, which was then dried with an infrared lamp to prepare a $$^{237}$$Np sample. The $$^{237}$$Np sample was quantified using 312-keV gamma ray emitted from $$^{233}$$Pa in a radiation equilibrium with $$^{237}$$Np. To monitor a thermal-neutron flux component at an irradiation position, the $$^{237}$$Np sample was irradiated together with several stable nuclides as neutron flux monitors: $$^{45}$$Sc, $$^{59}$$Co, $$^{98}$$Mo, $$^{181}$$Ta and $$^{197}$$Au. The reaction rate of $$^{237}$$Np was obtained from gamma-ray yields given by $$^{238}$$Np and $$^{233}$$Pa, and then the thermal-neutron capture cross section of $$^{237}$$Np was derived.

JAEA Reports

Preparation of carbonate slurry simulating chemical composition of slurry in overflowed high integrity container and evaluation of its characteristics

Horita, Takuma; Yamagishi, Isao; Nagaishi, Ryuji; Kashiwaya, Ryunosuke*

JAEA-Technology 2021-012, 34 Pages, 2021/07

JAEA-Technology-2021-012.pdf:2.1MB
JAEA-Technology-2021-012(errata).pdf:0.15MB

Waste mainly consisting of carbonate precipitates (carbonate slurry) from the Advanced Liquid Processing System (ALPS) and the improved ALPS at the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Holdings, Inc. have been storing in the High Integrity Container (HIC). The supernatant solution of carbonate slurry contained in some of HICs were overflowed in April of 2015. The all of level of liquid in the HICs were investigated; however, almost of the HICs were under the level of overflow. The mechanism of overflow suggested to be depending on the difference of the properties of the carbonate slurry such as the retention/release characteristics of the bubbles. Therefore, in order to clarify the mechanism of leakage, the repeatability experiment was carried out by using simulated carbonate slurry. The simulated carbonate slurry was perpetrated by using the same cross-flow filter system of the actual ALPS. Moreover, the preparative conditions for the simulated carbonate slurry were the same as Mg/Ca concentration ratio in inlet water of the ALPS (raw water) and the ALPS operating conditions. The chemical characteristics of simulated carbonate slurries were revealed by ICP-AES, pH meter, etc. The density of the settled slurry layer tended to increase depending on the calcium concentration in the raw water. The bubble injection test was conducted in order to investigate the bubble retention/release behavior in the simulated carbonate slurry layer. The simulated carbonate slurry with high settling density, which was generated by high calcium concentration solution was revealed to retain the injected bubbles. Since the ratio of concentration calcium and magnesium during the carbonate slurry generation is assumed to affect the retention of bubbles in the slurry layer, the information on the composition of raw water is one of important factor for overflow of HICs.

Journal Articles

Anisotropic physical properties of layered antiferromagnet U$$_2$$Pt$$_6$$Ga$$_{15}$$

Matsumoto, Yuji*; Haga, Yoshinori; Yamamoto, Etsuji; Takeuchi, Tetsuya*; Miyake, Atsushi*; Tokunaga, Masashi*

Journal of the Physical Society of Japan, 90(7), p.074707_1 - 074707_6, 2021/07

 Times Cited Count:0 Percentile:0.01(Physics, Multidisciplinary)

Journal Articles

Observation of longitudinal magnetic fluctuations at a first-order ferromagnetic quantum phase transition in UGe$$_2$$

Noma, Yuichiro*; Kotegawa, Hisashi*; Kubo, Tetsuro*; To, Hideki*; Harima, Hisatomo*; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika*; Ito, Kohei*; Nakamura, Ai*; et al.

Journal of the Physical Society of Japan, 90(7), p.073707_1 - 073707_5, 2021/07

 Times Cited Count:0 Percentile:0.01(Physics, Multidisciplinary)

Journal Articles

Electrochemical studies of uranium (IV) in an ionic liquid-DMF mixture to build a redox flow battery using uranium as an electrode active material

Ouchi, Kazuki; Komatsu, Atsushi; Takao, Koichiro*; Kitatsuji, Yoshihiro; Watanabe, Masayuki

Chemistry Letters, 50(6), p.1169 - 1172, 2021/06

 Times Cited Count:0 Percentile:0(Chemistry, Multidisciplinary)

The electrochemical behavior of uranium (IV) tetrachloride in ionic liquid-DMF mixture was studied for first time in order to build a redox flow battery (RFB) using U as an electrode active material. We found a quasi-reversible U$$^{III}$$/U$$^{IV}$$ couple that could be applied to the anode reaction of the RFB.

Journal Articles

Distribution of studtite and metastudtite generated on the surface of U$$_{3}$$O$$_{8}$$; Application of Raman imaging technique to uranium compound

Kusaka, Ryoji; Kumagai, Yuta; Yomogida, Takumi; Takano, Masahide; Watanabe, Masayuki; Sasaki, Takayuki*; Akiyama, Daisuke*; Sato, Nobuaki*; Kirishima, Akira*

Journal of Nuclear Science and Technology, 58(6), p.629 - 634, 2021/06

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

Journal Articles

Stoichiometry of lanthanide-phosphate complexes at the water surface studied using vibrational sum frequency generation spectroscopy and DFT calculations

Kusaka, Ryoji; Watanabe, Masayuki

Journal of Physical Chemistry B, 125(24), p.6727 - 6731, 2021/06

 Times Cited Count:0 Percentile:0(Chemistry, Physical)

Journal Articles

Nonmagnetic-magnetic transition and magnetically ordered structure in SmS

Yoshida, Shogo*; Koyama, Takehide*; Yamada, Haruhiko*; Nakai, Yusuke*; Ueda, Koichi*; Mito, Takeshi*; Kitagawa, Kentaro*; Haga, Yoshinori

Physical Review B, 103(15), p.155153_1 - 155153_5, 2021/04

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

JAEA Reports

Design and demonstration of the prototype nitrogen circulation refining system for nitride fuel fabrication (Contract research)

Iwasa, Toma; Takano, Masahide

JAEA-Technology 2020-024, 29 Pages, 2021/03

JAEA-Technology-2020-024.pdf:2.33MB

Partitioning and transmutation of minor actinides (MA) is an important issue to reduce volume and radio-toxicity of high-level radioactive wastes. In Nuclear Science Research Institute, we have been carrying out R&D on MA-bearing nitride fuel for accelerator driven system. In the actual nitride fuel fabrication process, a special nitrogen gas highly enriched with $$^{15}$$N is required to avoid $$^{14}$$C production from $$^{14}$$N by (n,p) reaction in the fuel. For the economical use of such expensive gas, we need a nitrogen circulation refining system that can remove carbon monoxide (CO) evolved by carbothermic nitridation of oxides and can use the nitrogen gas in the closed system without loss. To develop the system, at first we listed up the performance requirements, and then designed and assembled a prototype system for laboratory-scale demonstration. The system consists of CO removal unit and circulation unit that can automatically keep the system pressure and the gas flow rate constant. As a result of demonstration on the nitridation of oxide, both units completely satisfy the requirements. We confirmed that the concept can be applied to the actual fuel fabrication with further additional function such as automatic hydrogen feed for the control of decarburization.

JAEA Reports

Analysis of the radioactivity concentrations in low-level radioactive waste generated from JRR-3 and JPDR facilities

Tsuchida, Daiki; Haraga, Tomoko; Tobita, Minoru*; Omori, Hiroyuki*; Omori, Takeshi*; Murakami, Hideaki*; Mitsukai, Akina; Aono, Ryuji; Ishimori, Kenichiro; Kameo, Yutaka

JAEA-Data/Code 2020-022, 34 Pages, 2021/03

JAEA-Data-Code-2020-022.pdf:1.74MB

Radioactive wastes generated from nuclear research facilities in Japan Atomic Energy Agency are planning to be buried in the near surface disposal field. Therefore, it is required to establish the method to evaluate the radioactivity concentrations of radioactive wastes until the beginning of disposal. In order to contribute to this work, we collected and analyzed concrete samples generated from JRR-3 and JPDR. In this report, we summarized the radioactivity concentrations of 22 radionuclides($$^{3}$$H, $$^{14}$$C, $$^{36}$$Cl, $$^{41}$$Ca, $$^{60}$$Co, $$^{63}$$Ni, $$^{90}$$Sr, $$^{94}$$Nb, $$^{rm 108m}$$Ag, $$^{133}$$Ba, $$^{137}$$Cs, $$^{152}$$Eu, $$^{154}$$Eu, $$^{rm 166m}$$Ho, $$^{234}$$U, $$^{238}$$U, $$^{238}$$Pu, $$^{239+240}$$Pu, $$^{241}$$Am, $$^{243}$$Am, $$^{244}$$Cm) which were obtained from radiochemical analysis of the samples.

Journal Articles

Thermal-neutron capture cross sections and resonance integrals of the $$^{243}$$Am(n,$$gamma$$)$$^{rm 244g}$$Am and $$^{243}$$Am(n,$$gamma$$)$$^{rm 244m+g}$$Am reactions

Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Kimura, Atsushi

Journal of Nuclear Science and Technology, 58(3), p.259 - 277, 2021/03

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

Research and development were made for accuracy improvement of neutron capture cross section data on $$^{243}$$Am among minor actinides. First, the emission probabilities of decay $$gamma$$ rays were obtained with high accuracy, and the amount of the ground state of $$^{244}$$Am produced by reactor neutron irradiation of $$^{243}$$Am was examined by $$gamma$$-ray measurement. Next, the total amount of isomer and ground states was examined by $$alpha$$-ray measurement. Thermal-neutron capture cross sections and resonance integrals were derived both for the $$^{243}$$Am(n,$$gamma$$)$$^{rm 244g}$$Am and for $$^{243}$$Am(n,$$gamma$$)$$^{rm 244m+g}$$Am reactions.

Journal Articles

Single-crystal growth and magnetic phase diagram of the enantiopure crystal of NdPt$$_2$$B

Sato, Yoshiki*; Honda, Fuminori*; Maurya, A.*; Shimizu, Yusei*; Nakamura, Ai*; Homma, Yoshiya*; Li, D.*; Haga, Yoshinori; Aoki, Dai*

Physical Review Materials (Internet), 5(3), p.034411_1 - 034411_9, 2021/03

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

Journal Articles

The Chemistry of uranium (II); Method and practice

Sato, Nobuaki*; Kirishima, Akira*; Watanabe, Masayuki; Sasaki, Takayuki*; Uehara, Akihiro*; Takeda, Shino*

Uran No Kagaku (II); Hoho To Jissen, 143 Pages, 2021/03

This book describes necessary facts when readers would have an opportunity to treat Uranium for experiments. In the content, the method section shows experimental facilities and equipment including method, and the practical section mentions solution and solid state experiments using Uranium and/or radioisotopes.

Journal Articles

Universal scaling behavior under pressure in the heavy-fermion antiferromagnet CeRh$$_2$$Si$$_2$$; $$^{29}$$Si NMR study

Sakai, Hironori; Matsumoto, Yuji*; Haga, Yoshinori; Tokunaga, Yo; Kambe, Shinsaku

Physical Review B, 103(8), p.085114_1 - 085114_8, 2021/02

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

The microscopic origin of a magnetic phase diagram under pressure in a heavy fermion antiferromagnet CeRh$$_2$$Si$$_2$$ was investigated using the $$^{29}$$Si nuclear magnetic resonance (NMR) technique. We investigated the temperature and pressure dependencies of $$q$$-independent local fluctuations caused by the single-site Kondo effect. A universal scaling behavior observed on the energy scale of the local fluctuations in an entire pressure region demonstrates that a characteristic energy scale $$T_0$$ of Kondo interactions monotonically increases by applying pressure without a critical anomaly around the quantum critical pressure $$P_{rm c}$$ of antiferromagnetism. Our NMR result agrees with the Doniach picture of the heavy-fermion phase diagram, where the progressive delocalization of the $$f$$-electrons occurs across $$P_{rm c}$$, accompanied by the development of antiferromagnetic correlations among the $$f$$-electrons.

Journal Articles

Online measurement of the atmosphere around geopolymers under gamma irradiation

Cantarel, V.; Lambertin, D.*; Labed, V.*; Yamagishi, Isao

Journal of Nuclear Science and Technology, 58(1), p.62 - 71, 2021/01

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

The gas production of wasteforms is a major safety concern for encapsulating active nuclear wastes. For geopolymers and cements, the H$$_{2}$$ produced by radiolytic processes is a key factor because of the large amount of water present in their porous structure. Herein, the gas composition evolution around geopolymers was monitored on line under $$^{60}$$Co gamma irradiation. Transient evolution of the hydrogen production yield was measured for samples with different formulations. The rate of its evolution and the final values are consistent with the presence of a chemical reaction of the pseudo-first order consuming hydrogen in the samples. The results show this phenomenon can significantly reduce the hydrogen source term of geopolymer wasteform provided their diffusion constant remains low. Lower hydrogen production rates and faster kinetics were observed with geopolymers formulations in which pore water pH was higher. Besides hydrogen production, a steady oxygen consumption was observed for all geopolymers samples. The oxygen consumption rates are proportional to the diffusion constants estimated in the modelization of hydrogen recombination by a pseudo first order reaction.

Journal Articles

Solvent extraction of cesium using DtBuDB18C6 into various organic solvents

Sasaki, Yuji; Morita, Keisuke; Kitatsuji, Yoshihiro; Ito, Keisuke*; Yoshizuka, Kazuharu*

Solvent Extraction Research and Development, Japan, 28(2), p.121 - 131, 2021/00

 Times Cited Count:0 Percentile:0(Chemistry, Multidisciplinary)

High concentration of Cs is present in high-level radioactive waste. It is well-known that Cs is an alkali element and difficult to extract completely into an organic phase. Crown ether compounds are widely available for Cs extractants; DtBuDB18C6 (di-$$t$$-butyl-dibenzo-18crown6), was used in this study. Organic solvents used for the industrial applications, such as $$n$$-dodecane and 1-octanol, have low solubility concerning the compound; other solvents were employed and tested. In this study, ketone-, ether-, and ester-type solvents showed high solubility for DtBuDB18C6 and DtBuDB18C6, when dissolved in ketones and alcohols, exhibited relatively high Cs distribution ratios ($$D$$(Cs)), closely to 10.

Journal Articles

Flexible fuel cycle system for the effective management of plutonium

Fukasawa, Tetsuo*; Hoshino, Kuniyoshi*; Yamashita, Junichi*; Takano, Masahide

Journal of Nuclear Science and Technology, 57(11), p.1215 - 1222, 2020/11

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

The flexible fuel cycle initiative system (FFCI system) has been developed to reduce spent fuel (SF) amounts, to keep high availability factor for the reprocessing plant and to increase the proliferation resistance for the recovered Pu. The system separates most U from the SF at first, and the residual material called recycle material (RM) which contains Pu, minor actinides, fission products and remaining U will go to Pu(+U) recovery from the RM for Pu utilizing reactor in future. The Pu utilizing reactor is FBR or LWR with MOX fuel. The RM is the buffer material between SF reprocessing and Pu utilizing reactor with compact size and high proliferation resistance, which can suppress the amount of relatively pure Pu. The innovative technologies of FFCI are most U separation and temporary RM storage. They are investigated by the literature survey, fundamental experiments using simulated material and analyses using simulation code. This paper summarizes the feasibility confirmation results of FFCI.

Journal Articles

Improvement of adsorption performances of Sr adsorption fiber and investigation for realizing simple $$^{90}$$Sr analysis

Horita, Takuma; Asai, Shiho*; Konda, Miki; Matsueda, Makoto; Hanzawa, Yukiko; Kitatsuji, Yoshihiro

Bunseki Kagaku, 69(10/11), p.619 - 626, 2020/10

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

We have developed a Sr adsorption fiber for rapid analysis of $$^{90}$$Sr. The prepared Sr adsorption fiber has a Sr-extraction layer that densely retains a Sr-selective extractant, an 18-crown-6 ether derivative, on the fiber surface. Hydrophobic group-containing polymer chains embedded onto the surface of the fiber allow to form a hydrophobic phase, incorporating Sr-selective extractants. This unique surface structure provides high adsorption capacity, leading to rapid and highly efficient adsorption of Sr$$^{2+}$$. The adsorption capacity of the Sr adsorption fiber was 3 times higher than commercially available 18-crown-6 ether derivative-impregnated resin (Sr Resin). The equilibrium adsorption capacity of the Sr adsorption fiber was comparable to the Sr Resin. The retained $$^{90}$$Sr was finally determined by a GM counter. The total analysis time including the Sr adsorption and measurement was about 1 hour.

1561 (Records 1-20 displayed on this page)