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Watanabe, Masashi; Kato, Masato
Frontiers in Nuclear Engineering (Internet), 1, p.1082324_1 - 1082324_9, 2023/01
Since the oxygen potential and the oxygen coefficient of UO
have a significant impact on fuel performance, many experimental data have been obtained. However, experimental data of the oxygen potential and the oxygen diffusion coefficient in the high temperature region above 1673 K are very limited. In the present study, we aimed to obtain these data and analyze them by defect chemistry. The oxygen potentials and the oxygen chemical diffusion coefficient of UO were measured by the gas equilibrium method in the near stoichiometric region at temperatures ranging from 1673 to 1873 K. A data set of oxygen potentials was made together with literature data and analyzed by defect chemistry. The oxygen potential of UO was determined as a function of O/U ratio and temperature, and an equation representing the relationship was derived. The oxygen chemical diffusion coefficient values obtained in this study were reasonably close to the literature values. The oxygen partial pressure dependence of the oxygen chemical diffusion coefficients was predicted from the evaluated results of the oxygen potential data, but no clear dependence was observed.
Yanagisawa, Hiroshi
JAEA-Technology 2021-023, 190 Pages, 2021/11
JAEA-Technology-2021-023.pdf:5.25MB
Computational analyses on nuclear criticality characteristics were carried out for heterogeneous lattice systems composed of water moderator and fuel rods utilized in low-power research and test reactors, in which the depletion of fuel due to burnup is relatively small, by using the continuous-energy Monte Carlo code MVP Version 2 with the evaluated nuclear data library JENDL-4.0. In the analyses, the minimum critical number of fuel rods was evaluated using calculated neutron multiplication factors for the heterogeneous systems of the uranium dioxide fuel rod in the Static Experiments Critical Facility (STACY) and the Tank-type Critical Assembly (TCA), and the uranium-zirconium hydride fuel rod in the Nuclear Safety Research Reactor (NSRR). In addition, six sorts of the ratio of reaction rates, which are components of neutron multiplication factors, were calculated in the analyses to explain the variation of neutron multiplication factors with the ratio of water moderator to fuel volume in a unit fuel rod cell. Those results of analyses are considered to be useful for the confirmation of reasonableness and validity of criticality safety measures as data showing criticality characteristics for water-moderated heterogeneous lattice systems composed of the existing fuel rods in research and test reactors, of which criticality data are not sufficiently provided by the Criticality Safety Handbook.
Hosoma, Takashi
JAEA-Research 2015-009, 162 Pages, 2015/08
JAEA-Research-2015-009.pdf:22.3MB
Neutron coincidence counting assay systems have been developed in the last two decades. Objects would extend to high-mass uranium-plutonium dioxide containing other spontaneous fission nuclei, so essentials of neutron multiplicity counting were reconsidered and expanded: (a) Formulae of multiplicity distribution were algebraically derived up to septuplet using a probability generating function; (b) Leakage multiplication was evaluated not by Monte Carlo method but by an average length from an arbitrary point inside a sample to an arbitrary point on its surface and a probability of induced fission within the length; (c) Mechanism of coincidence counting was associated with a couple of different time axes in Poisson process, and consequently a pair of close-to-coincident neutrons from the process was derived. For the formulae, new expressions using combination were wrote down. For spectrum and mean free path, actually treated uranium-plutonium dioxide was selected as an example.
Mineo, Hideaki; Isogai, Hikaru; Morita, Yasuji; Uchiyama, Gunzo*
Journal of Nuclear Science and Technology, 41(2), p.126 - 134, 2004/02
Times Cited Count：7 Percentile：45.11(Nuclear Science & Technology)A simple equation was proposed for the dissolution rate of spent LWR fuel, of which the change in the dissolution area was estimated by taking into account of the area of the cracks occurring due to thermal shrinkage of the pellets during irradiation. The applicability of proposed equation was examined using LWR fuel dissolution test results in the present study as well as the results obtained by other workers. The equation showed good agreements with the dissolution test results obtained from spent fuel pellets and pulverized spent fuel. It was indicated that the proposed equation was simple and would be useful for the prediction of dissolution of spent LWR fuels. However, the initial effective dissolution area, the parameter of the equation, was found to depend on the temperature, which could not be explained by the proposed equation. Further studies on the role of other factors affecting dissolution rate, such as nitrous acid, in the dissolution of spent fuel was required.
Nakajima, Kunihisa; Arai, Yasuo
Journal of Nuclear Materials, 317(2-3), p.243 - 251, 2003/05
Times Cited Count：3 Percentile：25.79(Materials Science, Multidisciplinary)The Knudsen effusion mass-spectrometric measurement of pure UO
(s) are carried out at 1673, 1773 and 1873K to evaluate 
G
(UO
,g) as well as to measure the partial pressures of UO(g) and O(g) over UO(s) as function of the O/U ratio. It was found that the partial pressures of O(g) over UO(s) almost agree with the experimental data reported in the past and the values derived from the empirical equation given by Nakamura and Fujino. Further, it was found that the values of G(UO,g) obtained in this study are in good agreement with the recommended values.
Amaya, M.*; Une, Katsumi*; Minato, Kazuo
Journal of Nuclear Materials, 294(1-2), p.1 - 7, 2001/04
Times Cited Count：12 Percentile：64.73(Materials Science, Multidisciplinary)no abstracts in English
and (U,Gd)OMinato, Kazuo; Shiratori, Tetsuo; Serizawa, Hiroyuki; Hayashi, Kimio; Une, Katsumi*; Nogita, Kazuhiro*; Hirai, Mutsumi*; Amaya, M.*
Journal of Nuclear Materials, 288(1), p.57 - 65, 2001/01
Times Cited Count：21 Percentile：80.29(Materials Science, Multidisciplinary)no abstracts in English
fuelsUne, Katsumi*; Nogita, Kazuhiro*; Suzaka, Yojiro*; Hayashi, Kimio; Ito, Kunio*; Eto, Yoshinori*
International Topical Meeting on Light Water Reactor Fuel Performance, 2, p.775 - 785, 2000/00
no abstracts in English
bombarded with iodine and nickel ions at energies around 100 MeVHayashi, Kimio; ; Fukuda, Kosaku
Advances in Science and Technology, 24, p.439 - 446, 1999/00
no abstracts in English
; *
Nuclear Technology, 122(3), p.265 - 275, 1998/00
Times Cited Count：2 Percentile：24.49(Nuclear Science & Technology)no abstracts in English
by high-energy heavy ionsHayashi, Kimio; ; Fukuda, Kosaku
Journal of Nuclear Materials, 248, p.191 - 195, 1997/00
Times Cited Count：21 Percentile：82.17(Materials Science, Multidisciplinary)no abstracts in English
Okuno, Hiroshi; *
PHYSOR 96: Int. Conf. on the Physics of Reactors, 4, p.L74 - L82, 1996/00
no abstracts in English
Komiyama, Kazumasa*; Okuno, Hiroshi
JAERI-Research 94-047, 39 Pages, 1994/12
JAERI-Research-94-047.pdf:0.89MB
no abstracts in English
*; Arakawa, Takuya*; Okuno, Hiroshi
JAERI-Data/Code 94-018, 36 Pages, 1994/12
JAERI-Data-Code-94-018.pdf:1.09MB
no abstracts in English
Okuno, Hiroshi; Nomura, Yasushi
JAERI-Data/Code 94-014, 33 Pages, 1994/10
JAERI-Data-Code-94-014.pdf:0.98MB
no abstracts in English
Ogawa, Toru; Fukuda, Kosaku; Kashimura, Satoru; Tobita, Tsutomu; Kobayashi, Fumiaki; ; ; ; Kikuchi, Teruo
Journal of the American Ceramic Society, 75(11), p.2985 - 2990, 1992/11
Times Cited Count：40 Percentile：84.42(Materials Science, Ceramics)no abstracts in English
Okuno, Hiroshi; Naito, Yoshitaka; Sakurai, Y.*
Journal of Nuclear Science and Technology, 28(10), p.958 - 960, 1991/10
no abstracts in English
fuel grain size on reactivity; Continuous energy Monte Carlo calculationsSakurai, Y.*; Okuno, Hiroshi; Naito, Yoshitaka
JAERI-M 91-137, 35 Pages, 1991/09
no abstracts in English
-fuel grain size on reactivity; Study by ultra-fine energy group calculations using the computer codes based on the collision probability methodOkuno, Hiroshi; *
JAERI-M 91-107, 49 Pages, 1991/08
no abstracts in English
*; Ohashi, Hiroshi*; Morozumi, Takashi *; Ogawa, Toru; Fukuda, Kosaku
JAERI-M 90-113, 46 Pages, 1990/07
no abstracts in English
