Journal of Nuclear Science and Technology
Online ISSN : 1881-1248
Print ISSN : 0022-3131
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Volume 17, Issue 1
Displaying 1-12 of 12 articles from this issue
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  • Estimation of Average Void Fraction in Vertical Two-Phase Flow Channel under Low Liquid Velocity
    Yukio SUDO
    1980 Volume 17 Issue 1 Pages 1-15
    Published: January 25, 1980
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.17.1
    JOURNAL FREE ACCESS
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    During the reflood phase in a postulated loss-of-coolant accident of a pressurized water reactor, the driving force to feed the emergency core coolant into the core is the effective water head of a two-phase flow in the downcomer surrounding the core in the reactor vessel. The effective water head in the downcomer is dominated by the charac-teristics of the average void fraction in a vertical two-phase flow channel.
    This paper makes clear the effects of the physical properties of fluids, the channel diameter and superficial velocities of two phases on the void fraction in a vertical flow system by both carrying out the experiment of an air-water system under 1 atm and in-vestigating the previous experimental results of steam-water and air-water systems. As the results, the presentation of the average void fraction could be obtained within errors of ±15% by dimensional analyses in cases of both steam-water and air-water systems in the range of low superficial water velocities (<30 cm/s) including the stagnant water condition.
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  • Hidden State Variables and AR-MA Formulation of Reactor Noise
    Kuniharu KISHIDA, Hiroshi SASAKAWA
    1980 Volume 17 Issue 1 Pages 16-25
    Published: January 25, 1980
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.17.16
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    Coupled Markovian Langevin equations in the conventional reactor noise theory are cast into a time series model with the aid of contraction of information, coarse graining in time, and the concept of innovation. This makes it possible to physically interpret time series data and to apply them to reactor diagnosis. An evolution equation for the variance of the innovation is found and discussed in connection with the Riccati equation used in prediction theory. The relation with the Markovian representation well-known in control theory is also discussed. A simple example is treated to demonstrate that the time series model has less information than Langevin equations.
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  • Measurements of Thermal Disadvantage Factors in Light-Water Moderated PuO2-UO2 and UO2 Lattices
    Akio OHNO, Iwao KOBAYASHI, Harumichi TSURUTA, Masao HASHIMOTO, Takenor ...
    1980 Volume 17 Issue 1 Pages 26-36
    Published: January 25, 1980
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.17.26
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    The disadvantage factor for thermal neutrons in light-water moderated PuO2-UO2 and UO2 square lattices were obtained from measurements of thermal neutron density distri-butions in a unit lattice cell, measured with Dy-Al wire detectors. The lattices consisted of 3.4w/0 PuO2-UO2 and 2.6w/0 UO2 fuel rods, and the water-to-fuel volume ratio within the unit cell was parametrically changed. The PuO2-UO2 and UO2 fuel rods were designed to realize equal fissile atomic number density.
    The disadvantage factors thus measured were 1.36±0.07, 1.37±0.08, 1.40±0.06 and 1.38±0.06 in the PuO2-UO2 fuel lattices, and 1.30±0.06, 1.31±0.08, 1.30±0.08 and 1.33 ±O.06 in the UO2, for water-to-fuel volume ratios, of 1.76, 2.00, 2.38 and 2.95, respec-tively. This difference in disadvantage factor between PuO2-UO2 and UO2 fuel lattices corresponds to about 8%. Calculated results obtained by multigroup transport code LASER agreed well with the measured ones.
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  • Fast Neutron Spectra Transmitted through Iron and Sodium Slabs
    Kazuo SHIN, Tatsuo NISHIBE, Ryuji MURAKAMI, Haruyuki FUJITA, Tomonori ...
    1980 Volume 17 Issue 1 Pages 37-43
    Published: January 25, 1980
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.17.37
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    Transmitted neutron spectra were measured for Fe slabs of 9.6 and 19.2 cm thick and 1 and 2 canned Na slabs of 15 cm thick (thickness of the stainless-steel can was 3 mm). The neutrons from the core of fast neutron source reactor "YAYOI" of the Uni-versity of Tokyo were collimated and incident to the slabs. The intensity and the profile of the incident neutron beam was determined by a preliminary experiment. The transmitted neutrons were measured on the collimated axis and polar angle of 30° and 45° to the axis. Point-to-point Monte Carlo calculation was carried out for the purpose of comparison with experimental data. The results of the calculation showed good agree-ment to the experimental spectra.
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  • Determination of Effective Diffusion Parameters in Thermal Reactor Assemblies
    Toshikazu TAKEDA, Etsuro SAJI, Tamotsu SEKIYA
    1980 Volume 17 Issue 1 Pages 44-56
    Published: January 25, 1980
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.17.44
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    Effective diffusion parameters have been determined so as to preserve reaction rates in a super-assembly consisting of few assemblies with different neutronic properties. The effective diffusion parameters are used for few-group diffusion calculations in one- and two-dimensional models of thermal reactor cores. The results are compared with those from reference heterogeneous calculations which take into account heterogeneity in each assembly within the framework of diffusion theory, and those obtained by using the conventional flux-weighted group constants. The use of the effective diffusion param-eters results in a much more accurate prediction of the neutron multiplication factor and power densities than those predicted using the conventional flux-weighted group constants when using fine meshes.
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  • Synthesis of High Purity Uranium Mononitride from Oxide through Carbide
    Tadasumi MUROMURA, Hiroaki TAGAWA
    1980 Volume 17 Issue 1 Pages 57-66
    Published: January 25, 1980
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.17.57
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    The synthesis of UN from UO2 through carbide by oxide-carbide-nitride process has been studied in an NH3 stream and a mixed H2 and N2 stream at temperatures 1, 4001, 750°C. Uranium mononitride is produced from the carbide by the following four stages: (1) deposition of free carbon, (2) deposition and removal of free carbon in the two-phase field (C+UN1-xCx), (3) removal of free carbon in the three-phase field (UN1-xCx+C+N2), and (4) removal of combined carbon in the two-phase field (UN1-xCx+N2). The total amount of impurities (carbon+oxygen) in the UN obtained by the present method is in the range of 0.050.10w/0.
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  • Behavior of Iodine-131 during Rinsing In-Pile Loop with Demineralized Water after Fission Product Release Experiment
    Katsumune YAMAMOTO, Chozaburo NAKAZAKI, Seigo OKAGAWA, Iichiro YOKOUCH ...
    1980 Volume 17 Issue 1 Pages 67-76
    Published: January 25, 1980
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.17.67
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    After a fission product release experiment in one of the in-pile water loops (OWL-1) of Japan Atomic Energy Research Institute, the loop was flushed with fresh water and the concentration of 131I in the water was measured to clarify the behavior of 131I remaining in the loop.
    When the clean up system was shut off, the 131I concentration in the water gradually increased and reached a maximum after about 3 days and then decreased at the rate cor-responding to the half-life of 131I. From the results, some equations were mathematically derived, which predict not only the variation of 131I concentration in the water, but also the relationship between the amounts of 131I in the rinsing water and on the system walls.
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  • FCI-related Material Movements under LOF-driven-TOP Accident Condition of LMFBR
    Nobuo SHIMEGI
    1980 Volume 17 Issue 1 Pages 77-80
    Published: January 25, 1980
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.17.77
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  • Co-ordinated Control of Feedwater and Recirculation Systems for B W R Plant
    Tetsuo ITO, Takao SATO, Takashi OMORI, Masao HIROSE
    1980 Volume 17 Issue 1 Pages 80-82
    Published: January 25, 1980
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.17.80
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  • Dissolution and Solidification of Aluminum Capsule in Production of Mo-99 by Sublimation from Neutron-Irradiated UO2
    Masakazu TANASE, Masahiko ISSHIKI, Kenji SHIMOOKA, Kenji MOTOJIMA
    1980 Volume 17 Issue 1 Pages 83-85
    Published: January 25, 1980
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.17.83
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  • ERRATA
    1980 Volume 17 Issue 1 Pages 88a
    Published: 1980
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
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  • ERRATA
    1980 Volume 17 Issue 1 Pages 88b
    Published: 1980
    Released on J-STAGE: April 18, 2008
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