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Journal Articles

Defect equilibria and thermophysical properties of CeO$$_{2-x}$$ based on experimental data and density functional theory calculation result

Watanabe, Masashi; Nakamura, Hiroki; Suzuki, Kiichi; Machida, Masahiko; Kato, Masato

Journal of the American Ceramic Society, 105(3), p.2248 - 2257, 2022/03

https://doi.org/10.1111/jace.18249
 Times Cited Count：1 Percentile：6.98(Materials Science, Ceramics)

Properties of CeO$$_{2}$$ were evaluated by DFT simulation to determine band gap, Frenkel defect formation energy and defect migration energy. Band gap and Frenkel defect formation energy were used to analyze defect equilibria. Oxygen partial pressure dependence of defect equilibria was evaluated based on oxygen potential experimental data and DFT calculation, and a Brouwer diagram was derived. The defect formation energies, including Frenkel defect, electron-hole pair and so on, were determined and used to evaluate the properties, including oxygen diffusion coefficients, electrical conduction, heat capacity and thermal conductivity. Mechanisms of various properties were discussed for a deeper understanding based on defect chemistry, and the relationship among properties were systematically described.

Journal Articles

Relative oxygen potential measurements of (U,Pu)O$$_{2}$$ with Pu = 0.45 and 0.68 and related defect formation energy

Hirooka, Shun; Matsumoto, Taku; Sunaoshi, Takeo*; Hino, Tetsushi*

Journal of Nuclear Materials, 558, p.153375_1 - 153375_8, 2022/01

https://doi.org/10.1016/j.jnucmat.2021.153375
 Times Cited Count：2 Percentile：31.78(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Oxide-metal ratio dependence of central void formation of mixed oxide fuel irradiated in fast reactors

Ikusawa, Yoshihisa; Maeda, Koji; Kato, Masato; Uno, Masayoshi*

Nuclear Technology, 199(1), p.83 - 95, 2017/07

https://doi.org/10.1080/00295450.2017.1314748
 Times Cited Count：4 Percentile：37.06(Nuclear Science & Technology)

Based on thermal computation results obtained using an irradiation behavior analysis code, we have evaluated the effect of O/M ratio on fuel restructuring from the results of PIEs for the B14 irradiation test fuel, which was a mixed oxide fuel and was irradiated in the experimental reactor Joyo. The thermal computation results showed that fuel restructuring in the stoichiometric oxide fuel was accelerated, though the fuel temperature in the stoichiometric oxide fuel was evaluated as lower than that of the hypo-stoichiometric one. We explained this behavior as follows: first, the fuel temperature decreased due to the high thermal conductivity at stoichiometry; second, the pore migration velocity increased due to the increase in vapor pressure caused by the high vapor pressure of UO$$_{3}$$, which was derived from the high oxygen potential at stoichiometry. In addition, our results indicated that the central void diameter strongly depended on not only fuel temperature, but also vapor pressure.

Journal Articles

Oxygen potentials, oxygen diffusion coefficients and defect equilibria of nonstoichiometric (U,Pu)O$$_{2pm x}$$

Kato, Masato; Watanabe, Masashi; Matsumoto, Taku; Hirooka, Shun; Akashi, Masatoshi

Journal of Nuclear Materials, 487, p.424 - 432, 2017/04

https://doi.org/10.1016/j.jnucmat.2017.01.056
 Times Cited Count：12 Percentile：75.51(Materials Science, Multidisciplinary)

Oxygen potential of (U,Pu)O$$_{2pm x}$$ was evaluated based on defect chemistry using an updated experimental data set. The relationship between oxygen partial pressure and deviation $$x$$ in (U,Pu)O$$_{2pm x}$$ was analyzed, and equilibrium constants of defect formation were determined as functions of Pu content and temperature. Brouwer's diagrams were constructed using the determined equilibrium constants, and a relational equation to determine O/M ratio was derived as functions of O/M ratio, Pu content and temperature. In addition, relationship between oxygen potential and oxygen diffusion coefficients were described.

Journal Articles

Oxygen thermochemistry of urania-rare earth system; UO$$_2$$-CeO$$_2$$

Hirooka, Shun; Murakami, Tatsutoshi; Nelson, A. T.*; McClellan, K. J.*

INL/EXT-14-33515, p.34 - 36, 2014/10

https://doi.org/10.2172/1169217

Collaborative study has been done on the properties of nuclear materials between the DOE and Japan and the oxygen potential of (U,Ce)O$$_2$$ was measured in this year. Experimental measurements of the oxygen potential were conducted on Ce=20% and 30% composition rates simulating Pu content in advanced MOX fuel in JAEA by gas equilibrium method where oxygen partial pressure in the atmosphere was controlled with mixing dry/wet Ar/H$$_2$$ gas. More than 100 data points were obtained in the O/M range of 1.945 $$sim$$ 2.000 at 1200$$^{circ}$$C, 1400$$^{circ}$$C and 1600$$^{circ}$$C. The experimental results were analyzed by the defect analysis and analytical equations were obtained to calculate O/M as functions of temperature and oxygen potential. From the comparison with that of (U,Pu)O$$_2$$, applicability of the same defect chemistry and S-style curve are common. Also, it is revealed that (U,Ce)O$$_2$$ requires evidently higher oxygen potential for the O/M.

Journal Articles

Oxygen potential measurements of fluorite-type Zr$$_{0.5}$$Pu$$_{0.5}$$O$$_{2-y}$$ by EMF method

Otobe, Haruyoshi; Nakamura, Akio; Yamashita, Toshiyuki; Minato, Kazuo

Journal of Nuclear Materials, 344(1-3), p.219 - 222, 2005/09

https://doi.org/10.1016/j.jnucmat.2005.04.045
 Times Cited Count：3 Percentile：24.22(Materials Science, Multidisciplinary)

Actinides-bearing zirconias are prominent candidate materials for various nuclear applications: targets for actinide transmutation, inert material fuels, radioactive waste forms, etc. In this study, the oxygen potential (g(O$$_{2}$$)) behavior of fluorite-type (F-type) Zr$$_{0.5}$$Pu$$_{0.5}$$O$$_{2-y}$$ has been measured by EMF method using the zirconia oxygen sensor. It was found that the g(O$$_{2}$$) values of F-type Zr$$_{0.5}$$Pu$$_{0.5}$$O$$_{2-y}$$ were about 150 kJ/mol higher than those of F-type PuO$$_{2-y}$$ at the same oxygen-nonstoichiometric (O/M) values. The g(O$$_{2}$$) values of F-type Zr$$_{0.5}$$Pu$$_{0.5}$$O$$_{2-y}$$ were 50 kJ/mol lower than those of pyrochlore Zr$$_{2}$$Pu$$_{2}$$O$$_{7+x}$$ at the same O/M values. These results suggest that the g(O$$_{2}$$) behavior depends on the cation and anion ordering/disordering, in addition to the cation composition ratio (Zr/Pu).

Journal Articles

Thermodynamics of the UO$$_{2}$$ solid solution with magnesium and europium oxides

Fujino, Takeo*; Sato, Nobuaki*; Yamada, Kota*; Nakama, Shohei*; Fukuda, Kosaku; Serizawa, Hiroyuki; Shiratori, Tetsuo*

Journal of Nuclear Materials, 297(3), p.332 - 340, 2001/09

https://doi.org/10.1016/S0022-3115(01)00627-4
 Times Cited Count：4 Percentile：33.39(Materials Science, Multidisciplinary)

Oxygen potential of solid solution Mg$$_{y}$$Eu$$_{z}$$U$$_{1-y-z}$$O$$_{2+x}$$ was examined as a function of O/Metal ratio at 1000, 1100 and 1200$$^{circ}$$C. The O/Metal ratio which gave the steepest change of the oxygen potential(GOM) was 1.995 for y=0.05, z=0.1 and y=0.05, z=0.05. The position decreased to 1.908 at higher Mg$$^{2+}$$ concentration of y=0.1, z=0.05. The GOM did not change with temperature in a range 1000-1200$$^{circ}$$C. At GOM, a friction of 0.473 of total Mg$$^{2+}$$ occupy the interstitial position of the fluorite lattice.

JAEA Reports

Study on fission product behaviors with strong radioactivity in severe accidents

Yamawaki, Michio*; Yamaguchi, Kenji*; Ono, Futaba*; Huang, J.*; Harada, Yuhei; Hidaka, Akihide; Sugimoto, Jun

JAERI-Tech 2000-015, p.38 - 0, 2000/03

JAERI-Tech-2000-015.pdf:1.31MB

no abstracts in English

Journal Articles

Development of oxygen sensors using zirconia solid electrolyte for fuel rods

*; Endo, Yasuichi; Yamaura, Takayuki; Matsui, Yoshinori; Niimi, Motoji; Hoshiya, Taiji; Kobiyama, M.*; Motohashi, Yoshinobu*

JAERI-Conf 99-006, p.343 - 348, 1999/08

https://jopss.jaea.go.jp/pdfdata/JAERI-Conf-99-006.pdf

no abstracts in English

Journal Articles

Thermodynamic study of U$$_{1-y}$$Gd$$_{y}$$O$$_{2+x}$$ by solid state EMF measurements

Nakamura, Akio

Zeitschrift f$"u$r Physikalische Chemie, 207, p.223 - 243, 1998/00

no abstracts in English

JAEA Reports

None

Sato, Isamu*; *; ; Arima, Tatsumi*; ; Kajitani, Yukio

PNC TY9606 97-001, 117 Pages, 1997/07

PNC-TY9606-97-001.pdf:19.16MB

no abstracts in English

JAEA Reports

Development of oxygen sensing technology in an irradiated fuel rod; Characteristic test of oxygen sensor

Saito, Junichi; Hoshiya, Taiji; ;

JAERI-Tech 96-015, 58 Pages, 1996/03

JAERI-Tech-96-015.pdf:1.66MB

no abstracts in English

Journal Articles

Contribution to the study of the U-Cs-Mo-I-O system

Ugajin, Mitsuhiro; Nagasaki, Takanori*; Ito, Akinori

Journal of Nuclear Materials, 230(3), p.195 - 207, 1996/00

https://doi.org/10.1016/0022-3115(96)80014-6
 Times Cited Count：7 Percentile：54.42(Materials Science, Multidisciplinary)

no abstracts in English

JAEA Reports

Thermochemical calculations for the urania-cesium iodide reaction

Ugajin, Mitsuhiro

JAERI-M 92-065, 113 Pages, 1992/05

JAERI-M-92-065.pdf:2.03MB

no abstracts in English

Journal Articles

Phase relation and thermodynamic properties of cubic fluorite-type solid solution, Ba$$_{y/2}$$Y$$_{y/2}$$U$$_{1-y}$$O$$_{2+x}$$(x$$>$$0,x=0,x$$<$$0)

Fujino, Takeo*; Yamashita, Toshiyuki; Ouchi, Kinji

Journal of Nuclear Materials, 183, p.46 - 56, 1991/00

https://doi.org/10.1016/0022-3115(91)90469-N
 Times Cited Count：9 Percentile：69.46(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Composition and oxygen potential of cubic fluorite-type solid solution Eu$$_{y}$$U$$_{1-y}$$O$$_{2+x}$$(x$$>$$0,x$$<$$0) and rhombohedral Eu$$_{6}$$UO$$_{12+x}$$(x$$<$$0)

Fujino, Takeo; Ouchi, Kinji; *; *; *

Journal of Nuclear Materials, 174, p.92 - 101, 1990/00

https://doi.org/10.1016/0022-3115(90)90426-N
 Times Cited Count：25 Percentile：89.09(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Application of Kirkwood-Buff theory to the study of the oxygen potential of nonstoichiometric ternary uranium oxides

Journal of Nuclear Materials, 114(2-3), p.242 - 249, 1983/00

https://doi.org/10.1016/0022-3115(83)90263-5
 Times Cited Count：0 Percentile：0.02(Materials Science, Multidisciplinary)

no abstracts in English

JAEA Reports

Chemical Interaction in Uranium-Plitnium Mixed Oxide Fuel Pins for LMFBR; Review

JAERI-M 8688, 44 Pages, 1980/02

JAERI-M-8688.pdf:1.76MB

no abstracts in English

Journal Articles

The Chemical state of burnup-simulated (Th,U)O$$_{2}$$ at high oxygen potential

Ugajin, Mitsuhiro; Shiba, Koreyuki

Journal of Nuclear Materials, 91(1), p.227 - 230, 1980/00

https://doi.org/10.1016/0022-3115(80)90051-3
 Times Cited Count：14 Percentile：94.62(Materials Science, Multidisciplinary)

no abstracts in English

Oral presentation

Oxygen potential measurement of (U,Ce)O$$_{2}$$

Murakami, Tatsutoshi; Kato, Masato; Nelson, A.*; McClellan, K.*

no journal, , 

no abstracts in English

32 (Records 1-20 displayed on this page)