Journal of Nuclear Science and Technology
Online ISSN : 1881-1248
Print ISSN : 0022-3131
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Volume 1, Issue 4
Displaying 1-7 of 7 articles from this issue
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  • Thermal Decomposition of Uranyl Nitrate Hexahydrate in the Presence of Graphite
    Kazumi IWAMOTO
    1964 Volume 1 Issue 4 Pages 113-119
    Published: 1964
    Released on J-STAGE: February 28, 2008
    DOIhttps://doi.org/10.3327/jnst.1.113
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    An attempt has been made to pursue the course of the thermal decomposition of uranyl nitrate hexahydrate in the presence of graphite, and compositions of the product at various stages in the decomposition have been determined by X-ray diffraction and by thermogravimetric measurement. The influence of graphite on the decomposition appeared in the temperature region above 500 ??, and reduction with graphite of the decomposed product into uranium dioxide was observed above 750 ?? . It was also demonstrated that uranium dioxide and carbide-dispersed graphite-base fuel could be prepared by thermal decomposition of hexahydrate in the graphite matrix.
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  • Characteristic Spectra in Neutron Thermalization, (II)
    The Effect of Chemical Binding
    Akira FURUHASHI
    1964 Volume 1 Issue 4 Pages 120-129
    Published: 1964
    Released on J-STAGE: February 28, 2008
    DOIhttps://doi.org/10.3327/jnst.1.120
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    The method of modal expansion for the time-dependent thermal neutron spectra is extended to include the effect of chemical binding of heavy moderators. The Laguerre moments in energy transfer are calculated from the generalized phonon frequency spectrum. The heavy gas model is treated as a special case. It is shown that the heavy mass approximation corresponds to neglect of multiple phonon processes in the energy exchange mechanism.
    Numerical calculations are made for heavy Einstein solids. It is concluded that thermalization time constant diminishes with increasing energy quantum more rapidly than the second moment of the energy transfer kernel. In contrast to the time decay constants, the characteristic spectra are not strongly influenced by chemical binding. It is also shown that the Doppler approximation appreciably underestimates the effect of chemical binding.
    Finally, diffusion cooling in chemically bound system is discussed by assuming the energy-independent diffusion constant, and the possibility is suggested that, in a strongly chemically bound system, the first higher mode in energy may decay more slowly than the first higher mode in space.
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  • Reactor Noise Analysis of Swimming Pool Type Reactor
    Shuji YAMADA
    1964 Volume 1 Issue 4 Pages 130-136
    Published: 1964
    Released on J-STAGE: February 28, 2008
    DOIhttps://doi.org/10.3327/jnst.1.130
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    Reactor power frequency spectrum measurements at various power levels (0.2W, 1W, 5W, 100W, 500W, 5kW and 100kW) were made with HTR** (swimming-pool type). A low frequency AC amplifier, a magnetic tape recorder, a frequency selective amplifier with twin-T filters, a multiplier, and an integrator were used. Speed-up and speed-down techniques of tape recorder were convenient for extending the frequency range of the analysis.
    The measured frequency spectrum of reactor noise determined the modulus of zero power transfer function, and indicated a prompt neutron mean life time of (7.58±1.58)×10-5 sec based on an effective delayed neutron fraction of 0.0082. The calculations were made with a HIPAC-103 computer. At higher power, some resonance peaks were found in the low frequency region. The absolute value of reactor power obtained by noise analysis agreed within 3% with the power meter indication at the power below 5kW.
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  • Research of Radioisotope Production with Fast Neutrons, (V)
    Trial Preparation of Carrier-Free 65Ni
    Eiji SHIKATA
    1964 Volume 1 Issue 4 Pages 137-140
    Published: 1964
    Released on J-STAGE: February 28, 2008
    DOIhttps://doi.org/10.3327/jnst.1.137
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    The preparation of carrier-free 65Ni was studied using the reaction 65Cu(n, p) 65Ni in a nuclear reactor. High purity copper metal was irradiated for 20 min in the JRR-2 reactor. Nickel-65 formed in the copper target was separated by anion exchange method. About 1 μc 65Ni per gram of copper was obtained by irradiation with a fast neutron flux of 9×1011 n/cm2/sec and thermal neutron flux of 3.6×1013 n/cm2/sec. The specific activity was greater than 3 mc/mg Ni which was over 600 times more than that produced by (n, γ) reaction on nickel irradiated at the same time. However, the reaction yield of 65Ni per gram of target by the (n, p) reaction was only 1/5, 000 of that by the (n, γ) reaction, so that it proved that the method would be unsuitable for practical application.
    The cross section for the reaction 65Cu(n, p) 65Ni has been estimated semi-theoretically to be 0.6mb, an experimental value of 0.2mb was calculated from the results of the present work.
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  • Preliminary Observations of Single Crystals of UO2 by Transmission Electron Microscope
    Shoichi NASU, Ryuzo UEDA
    1964 Volume 1 Issue 4 Pages 141-142
    Published: 1964
    Released on J-STAGE: February 28, 2008
    DOIhttps://doi.org/10.3327/jnst.1.141
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  • Errata
    1964 Volume 1 Issue 4 Pages 143a
    Published: 1964
    Released on J-STAGE: April 21, 2008
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  • Errata
    1964 Volume 1 Issue 4 Pages 143b
    Published: 1964
    Released on J-STAGE: April 21, 2008
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