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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

 Times Cited Count:1 Percentile:75.88(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

 Times Cited Count:1 Percentile:75.88(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 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

 Times Cited Count:3 Percentile:73.15(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

 Times Cited Count:3 Percentile:70.36

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 $$^{o}$$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 $$^{o}$$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

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

 Times Cited Count:7 Percentile:43.1

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

 Times Cited Count:9 Percentile:29.05

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

 Times Cited Count:22 Percentile:11.62

no abstracts in English

Journal Articles

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

J.Nucl.Mater., 114(2-3), p.242 - 249, 1983/00

 Times Cited Count:0 Percentile:100

no abstracts in English

JAEA Reports

Journal Articles

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

Ugajin, Mitsuhiro; Shiba, Koreyuki

J.Nucl.Mater., 91(1), p.227 - 230, 1980/00

 Times Cited Count:14 Percentile:5.1

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

Oral presentation

Thermodynamic assessment of the U-Fe-O system

Shirasu, Noriko; Otobe, Haruyoshi; Kurata, Masaki

no journal, , 

The phase relations of the U-Fe-O system and the phase stability of the ternary compound UFeO$$_{4}$$ were investigated. The thermodynamic modelling has been performed for the U-Fe-O ternary system based on the obtained data and reported phase diagram of UO$$_{2}$$-FeO$$_{1+x}$$ system.

Oral presentation

Thermal properties of (U,Ce)O$$_{2pm x}$$

Hirooka, Shun; Murakami, Tatsutoshi; Kato, Masato; Suzuki, Kiichi; Nelson, A.*; White, J.*; McClellan, K.*

no journal, , 

no abstracts in English

Oral presentation

The Oxygen potential measurement of (U$$_{0.623}$$Pu$$_{0.35}$$Am$$_{0.027}$$)O$$_{2{pm}x}$$ under high temperature

Matsumoto, Taku; Kato, Masato; Morimoto, Kyoichi; Sunaoshi, Takeo*

no journal, , 

The oxygen potentials of (U$$_{0.623}$$Pu$$_{0.35}$$Am$$_{0.027}$$)O$$_{2{pm}x}$$ were measured as a function of oxygen to metal ratio (O/M) in the temperature range from 1673 to 1873 K by the gas equilibrium method using thermogravimetry. The measured oxygen potentials were analyzed by the point defect chemistry method. From this analysis, the oxygen potential of (U$$_{0.623}$$Pu$$_{0.35}$$Am$$_{0.027}$$)O$$_{2{pm}x}$$ was represented as a function of O/M ratio and temperature.

28 (Records 1-20 displayed on this page)