Journal of Nuclear Science and Technology
Online ISSN : 1881-1248
Print ISSN : 0022-3131
Volume 17, Issue 6
Displaying 1-11 of 11 articles from this issue
  • Nobuhiko MATSUMOTO, Toshiyuki KAMEOKA, Kiyoshi TOKIEDA, Yoshizo OKAMOT ...
    1980 Volume 17 Issue 6 Pages 397-403
    Published: June 25, 1980
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    Thermal insulation system is often used to high temperature gas-cooled reactors. In the present paper, transient behavior of the gas flow in thermal insulation media is ex- perimentally studied in the case of sudden decrease of coolant pressure. The structure of these systems is capable of substituting for the simplified model that the gas in a container filled with porous insulation media exhausts from a balancing hole to the main flow. In the case of rapid depressurization, transient behaviors are measured by pressure sensors along an axial direction of the insulation layer, changing experimental parameters such as pressure gradient, opening of a balancing hole and packed density. The induced pressure is measured along the axial direction of the insulation layer. The induced pres- sure difference and the peak value of pressure difference are summarized with parameters. Lastly, a satisfactory agreement between experimantal and analytical results is obtained for several specified cases of testing.
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  • Out-Pile Experiment
    Yoshiaki HIMENO, June TAKAHASHI
    1980 Volume 17 Issue 6 Pages 404-412
    Published: June 25, 1980
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    Sodium mist behavior in argon cover gas space over sodium pool was investigated ex-perimentally using of a test vessel having cover gas volume of 100l. Mass concentration and gravitational settling flux of the mist (i.e. sodium aerosol) were determined between pool temperature range of 290520°C. Apparatuses used for the concentration determination were a He-Ne laser mist concentration meter (LCM) and mist traps, which were developed specifically for the present experiment. The mist gravitational settling flux φ was determined by using of collection plates, which were exposed to the mist entrained cover gas over sodium pool.
    The experimental results revealed that the concentration C was very high from 0.15 to 20 g/m3. It increased with pool temperature. The mist particle radii, which were determined from the gravitational settling flux ψ and decay curve of the concentration, were from 1.5 to 13 μm in the range of the present experiment. The vapor evaporation rate φe from the pool surface, which were also determined from the experimental ψ data, were found to increase with saturated vapor pressure Ps at pool surface. This rate did not depend so strongly on experimental geometries and cover gas flow convection pattern over sodium pool. Evaluations of transient C changing and steady state C fluctuation indicated that the mist formation was occurred near the pool surface.
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  • Michitsugu MORI, Saburo TODA, Masa-aki OCHIAI, Shinzo SAITO
    1980 Volume 17 Issue 6 Pages 413-424
    Published: June 25, 1980
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    Out-of-pile experiments were performed with Zircaloy-4 rods in subcooled water envi-ronment to study the basic phenomena occurring in the transient cooling process undergone by a fuel rod during a reactivity-initiated accident (RIA) affecting a light water reactor (LWR). The experimental results show that the cooling process of the fuel rod during an RIA can be divided into three phases separated by the quenching temperature Tq and the rewetting temperature Tr.
    It is also noted from the experimental results that with increasing degree of subcool-ing, Tq tends to rise to levels far exceeding the maximum liquid superheat temperature of water ; Tr, on the other hand, is little affected by the cooling water temperature, and remains close to that of the maximum superheat temperature.
    Numerical calculations indicate conclusively that radial heat transfer to coolant water is the dominant factor that governs the transient cooling process in an RIA affecting the cold start-up of a BWR, rather than the axial heat conduction through rod which is con-sidered to be the basic mechanism of cooling that governs the reflooding process during a LOCA.
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  • Kouichi KAMIUTO, Kiyoshi NAKAGAWA, Ryozo ECHIGO, Shu HASEGAWA, Yoshihi ...
    1980 Volume 17 Issue 6 Pages 425-435
    Published: June 25, 1980
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    An experimental and analytical study has been performed to clarify the effect of porous bodies on heat transfer at high temperatures. It is found that placing porous bodies in a duct, prominent heat transfer enhancement is attained due to both the absorption of intensive thermal radiation from the heating wall and the promotion of convective heat transfer by porous bodies and that radiation effect is notably appeared in the porous bodies with high permeability. On the other hand, analytical model developed here is successfully applied to predict the effect of radiation on heat transfer and the excellent agreements between the theory and the experiment are obtained.
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  • Haruyuki FUJITA, Sakae OKADA, Kunio FUJITA, Hiroshi SAKAMOTO, Kunio HI ...
    1980 Volume 17 Issue 6 Pages 436-442
    Published: June 25, 1980
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    Experiments were performed to study the ratio of permeabilities of protium to tritium through Pd-Ag-Au alloy at the conditions of 350°C ?? T ?? 550°C and p<1, 000 mmHg.
    The observed ratio was 2.12±0.03 at 350°C, and it was almost independent of temperature. It is remarkable that the obtained ratio of permeabilities is considerably larger than the square root of the atomic weight ratio √3.
    The dependence of separation factor for the hydrogen isotopes on pressure and "cut" is also discussed.
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  • Ruthenium Species Appearing in Fluorination Step as Identified by Thermochromatography and IR Measurements
    O. CORBIN, A. VANDERCHMITT, M. LUCAS
    1980 Volume 17 Issue 6 Pages 443-447
    Published: June 25, 1980
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    The following three reactions were studied by thermochromatography in relation to the reprocessing of oxide fuels : (a) fluorination of RuF3 by F2, (b) fluorination of RuO2 by F2, (c) fluorination of RuO2 mixed with an excess of an oxide UO2 or Y2O3. The reaction products were as follows. The RuF3-F2 reaction yields RuF5. Fluorination of RuO2 by F2 results in the production of a mixture of RuF4-RuF5-RuOF4. (RuF5 may be produced by fluorination of RuF4 resulting from decomposition of RuOF4 in the apparatus for thermochromatography). When dried at 150°C prior to fluorination the products of RuO2-F2 reaction in the presence of an excess UO2 on Y2O3 are much more volatile than those obtained in the absence of these oxides. More than 60% is a mixture of RuF5 and RuO, with a smaller amount of RuOF4, RuF4 and RuF5. When the RuO2-Y2O3 or UO2 are dried at 800°C prior to fluorination, RuO4 and RuF6 are also produced, but the yields is about 1020%. Results from I. R. measurements are interpreted the same way.
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  • Masami SHIMIZU, Toshifusa DOI, Asashi KITAMOTO, Yoichi TAKASHIMA
    1980 Volume 17 Issue 6 Pages 448-460
    Published: June 25, 1980
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    In order to study the separation characteristics for a pair of dual temperature mul-tistage-type H2/H2O-exchange columns, each stage of which is composed of the scrubbing packed bed for the water/vapor isotopic exchange and the hydrophobic Pt catalyst bed for the vapor/hydrogen isotopic exchange, the authors tried to compose the finite difference equations considering the water/vapor isotopic exchange and the vapor/hydrogen isotopic exchange and then made it possible to calculate the D-content in the water, vapor and hydrogen at any point in a pair of dual temperature multistage-type H2/H2O-exchange columns by way of six variable one order matrix equation derived from the six boundary conditions.
    Utilizing the results mentioned above, the authors tried a further study to get an optimum value of hydrogen/water molar flow ratio, number of stages in a cold column and a hot column, degradation ratio ((ZWB - Z-WF)/ZWB) and specific volume (m3/kmol D2O•h) of a pair of dual temperature multistage-type H2/H2O-exchange columns, in an example case where the temperature in the cold and hot columns, the enrichment factor, the catalytic exchange efficiency and scrubbing efficiency were given at normal pressure.
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  • Susumu MINATO
    1980 Volume 17 Issue 6 Pages 461-469
    Published: June 25, 1980
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    Data of variations in natural background r-radiation flux density obtained from observa-tions near the ground surface made for a period of almost 1 year are given together with data on simultaneous measurements on changes in various environmental influencing factors, such as the degree of soil dryness, atmospheric radon daughter concentration and rainfall rate. Statistical and time series analyses of these data have provided much information on the relationships between the flux density and influencing factors and periodical char-acteristics of those variations in the natural environment. It is concluded from the results of the analyses that the atmospheric randon daughters and rainfall play an important role in short- and middle-term variations in the background radiation flux, while the change of soil dryness contributes to long-term variations.
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  • Makoto OBU
    1980 Volume 17 Issue 6 Pages 471-473
    Published: June 25, 1980
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
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  • Shungo IIJIMA, Hisao YAMAKOSHI
    1980 Volume 17 Issue 6 Pages 474-476
    Published: June 25, 1980
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
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  • Hisao YAMAKOSHI, Shungo IIJIMA
    1980 Volume 17 Issue 6 Pages 477-479
    Published: June 25, 1980
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
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