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Kato, Masato; Komeno, Akira; Uno, Hiroki*; Sugata, Hiromasa*; Nakae, Nobuo; Konashi, Kenji*; Kashimura, Motoaki
Journal of Nuclear Materials, 393(1), p.134 - 140, 2009/08
Times Cited Count:41 Percentile:92.61(Materials Science, Multidisciplinary)In plutonium compounds, the lattice parameter increases due to self-radiation damage by -decay of plutonium isotopes. The lattice parameter change and its thermal recovery in plutonium and uranium mixed dioxide (MOX) were studied. The lattice parameter for samples of MOX powders and pellets that had been left in the air for up to 32 years was measured. The lattice parameter increased and was saturated at about 0.29%. The change in lattice parameter was formulated as a function of self-radiation dose. Three stages in the thermal recovery of the damage were observed in temperature ranges of below 673K, 673-1073K and above 1073K. The activation energies in each recovery stage were estimated to be 0.12 eV, 0.73 eV and 1.2 eV, respectively, and the corresponding mechanism for each stage was considered to be the recovery of the anion Frenkel defect, the cation Frenkel defect and a defect connected with helium, respectively.
Kato, Masato; Konashi, Kenji*; Nakae, Nobuo
Journal of Nuclear Materials, 389(1), p.164 - 169, 2009/05
Times Cited Count:23 Percentile:83.37(Materials Science, Multidisciplinary)Stoichiometries in (UPu)O and (UPu)O were analyzed from the experimental data of oxygen potential based on point defect chemistry. The relation between the deviation x from stoichimetric composition and oxygen partial pressure were evaluated. The concentrations of the point defects in MOX were estimated from the measured data of oxygen potential as functions of temperature and using Krger-Vink diagram. The analysis results showed that x was proportional to near stoichiometric region of both (UPu)O and (UPu)O, which suggested that intrinsic ionization was dominant defect. The model to calculate oxygen potential was derived and represented the experimental data with precision, and thermodynamic data.
Nakae, Nobuo
PNC TN1102 97-015, 27 Pages, 1997/12
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Komoda, S.; Nakae, Nobuo; Matsumoto, Mitsuo
Journal of Nuclear Materials, 188, p.319 - 322, 1992/00
Times Cited Count:0 Percentile:0.01(Materials Science, Multidisciplinary)Abe, Tomiyuki; Nakae, Nobuo; Kodato, Kazuo; Matsumoto, Mitsuo
Journal of Nuclear Materials, 188, p.154 - 161, 1992/00
Times Cited Count:6 Percentile:53.2(Materials Science, Multidisciplinary)Nakae, Nobuo; ;
Donen Giho, (70), p.77 - 81, 1989/06