Journal of Nuclear Science and Technology
Online ISSN : 1881-1248
Print ISSN : 0022-3131
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Volume 6, Issue 1
Displaying 1-11 of 11 articles from this issue
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  • Chemical Bonding of Thorium Monocarbide
    Tsuneo SATOW, Shigeru TAMAKI
    1969 Volume 6 Issue 1 Pages 1-5
    Published: January 25, 1969
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.6.1
    JOURNAL FREE ACCESS
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    The magnetic susceptibility of non-stoichiometric thorium monocarbide having compositions between ThC0.72 and ThC0.96 was measured at various temperatures. The susceptibility showed weak paramagnetism independent of temperature, which increased with decreasing carbon content (χmole=6.0 X10-5 emu for ThC0.72, 4.1X10-5 emu for ThC0.96). The bonding of Th-Th, Th-C and C-C is discussed with the aid of a metallic bonding model applied to the compound. The bond energies of Th-Th and Th-C have been analyzed on the basis of Pauling's scheme, and evaluat-ed to be -51 kcal/mole and -271 kcal/mole respectively, at a composition of ThC0.95. The narrow band of ThC is examined from measured results of magnetic susceptibility.
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  • Preparation of Uranium Carbide from Uranium Tetrafluoride
    Takashi MITAMURA, Masayoshi KANNO, Takashi MUKAIBO
    1969 Volume 6 Issue 1 Pages 6-11
    Published: January 25, 1969
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.6.6
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    The reaction of UF4 with Al and graphite to form UC has been studied in the temperature range between 900° and 1, 200°C. From a mixed powder of stoichiometric composition, UC with a small amount of UF3 was obtained, corresponding to the reaction
    3UF4+4Al+3C→3UC+4AlF3
    under constant flow of Ar.
    The X-ray pattern of the product from 300min reaction at 1, 200°C revealed the presence solely of UC phase. Taking the effect of Al content into consideration, the reaction is better explained by the reaction formula
    UF4+2Al+C→UCH+AlF+AlF3.
    The by-products were ascertained by chemical and X-ray analyses. The reaction follows a logarithmic law derived from the weight change us. holding time curves. Products of single phase of UC were obtained within a relatively short time above 1, 000°C. The apparent activation energy of the reaction was determined to be 64kcal/mol.
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  • A Method for Determination of Plutonium in Blood by Anion Exchange
    Jun AKAISHI
    1969 Volume 6 Issue 1 Pages 12-19
    Published: January 25, 1969
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.6.12
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    The anion exchange behavior of Pu(IV) and Pu(VI) were studied in solutions of both nitric acid and of ethanol-nitric acid mixture, and a method of determining plutonium content in blood was developed. About 10ml of blood were wet-incinerated with concentrated nitric acid and evaporated to dryness. The residue was dissolved in 8ml of 8 N nitric acid, and 12 ml of ethanol was added. The solution was passed through a resin column of Dowex 2, X8 (9 mm diem., 3.0 cm long). After washing the column with ethanol-nitric acid mixed solution, plutonium was eluted with 10 ml of 1 N nitric acid containing sulfur dioxide. The eluate was transferred to a cell for electrodeposition, which was carried out with 500 mA/cm2 for 3 hr using a stainless steel disk as cathode.
    The plutonium yield from the ion exchange was 8591%, and the electrodeposition quanti-tative. The blank activity from the reagents, resin and disk was 10-14Ci. With this method a 10-hr count with silicone semiconductor spectrometer, will permit determination of 5X10-1410-13Ci of plutonium in 10 ml of blood.
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  • New Approximate Analysis of Nonlinear Space-Dependent Reactor Dynamics due to Reactivity Accidents
    Jiro WAKABAYASHI, Hidekazu YOSHIKAWA
    1969 Volume 6 Issue 1 Pages 20-27
    Published: January 25, 1969
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.6.20
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    The nonlinear space-dependent reactor dynamics related to reactivity accidents have been studied analytically by means of a modified Helmholtz modal expansion method. In this method the neutron fluxes and delayed neutron precursors are expanded in terms of steady state or asymptotic shapes (persisting mode shapes) and of the shapes of higher eigenfunctions of the Helmholtz equation satisfying the boundary conditions that the values of eigenfunctions at the extrapolated boundary of reactor are zero.
    The expansion coefficients are time-dependent, and are obtained by solving simultaneous nonlinear differential equations.
    A code (SPEX-1) was developed for the computations related to this analysis, with which a sample calculation was performed on a problem concerning the self-shutdown behavior due to Doppler feedback in a power excursion.
    The merits of the modified Helmholtz modal expansion method are as follows:
    (1) Improved convergency of the solution as compared with the conventional modal expansion procedure;
    (2) Easy comparison with the one-point kinetic model;
    (3) Simplicity of the procedure of calculations related to power excursion analysis.
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  • A Stochastic Operator Method of Calculating the Time Interval Distributions in Neutron Detection
    Kunitoshi KURIHARA, Tamotsu SEKIYA
    1969 Volume 6 Issue 1 Pages 28-34
    Published: January 25, 1969
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.6.28
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    An operator method has been applied to formulate probability distribution functions of neutron counts in a reactor.
    Assuming all statistical events occurring in the reactor to be Markovian, an operator representation of the no count probability for a given time interval is given. The basic equation for the probability is derived from the Kolmogorov-Chapman equation, and the formal solution obtained thereof. Approximate expressions are also given, for two types of detectors- absorption and fission. The effects of moments of order higher than the second are evaluated numerically.
    Further development of the operator calculus has yielded relations connecting the waiting time distribution and the interval distribution with the no count probability.
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  • Studies of the Criticality of 20% Enriched Uranium Fast Critical Assemblies (FCA-I)
    Jitsuya HIROTA, Shoji NOMOTO, Naohiro HIRAKAWA, Masafumi NAKANO
    1969 Volume 6 Issue 1 Pages 35-42
    Published: January 25, 1969
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.6.35
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    A series of critical experiments and analyses have been made on cylindrical assemblies fueled with 20 % enriched uranium metal in the JAERI fast critical facility.
    The first assembly contains in the core 10.8 % of stainless steel and 6.5 % of void by volume, and is provided with a natural uranium blanket 30 cm thick. Based on a number of correction experiments, the critical mass of the assembly was determined to be 94.9±0.3 kg of 235U. With a reduced blanket thickness of 10 cm, the critical mass was found to increase by 16.4 %. When one quarter of the enriched uranium metal was substituted by graphite, the critical mass increased by 36.6 %.
    Comparison of these results with theoretical calculations indicated that the criticality of the assemblies can be well estimated by means of the Sn Sapproximation with ANL-635 set.
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  • A Note on the Heterogeneity Effect of Sodium Scattering Resonance on Neutron Spectrum
    Tatsuzo TONE
    1969 Volume 6 Issue 1 Pages 43-44
    Published: January 25, 1969
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.6.43
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  • A Method of Isotopic Ratio Determination of Uranium by Ge(Li) Detector
    Ren CHIBA, Katsuyuki EBISAWA
    1969 Volume 6 Issue 1 Pages 45-46
    Published: January 25, 1969
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.6.45
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  • Some Improvements on Spherical Capsule Type Glass Dosimeter
    Ryosuke YOKOTA, Yuhei MUTO, Jiro NAOI, Shunji NISHIJIMA
    1969 Volume 6 Issue 1 Pages 46-48
    Published: January 25, 1969
    Released on J-STAGE: April 18, 2008
    DOIhttps://doi.org/10.3327/jnst.6.46
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  • Errata
    1969 Volume 6 Issue 1 Pages 48b
    Published: 1969
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
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  • Errata
    1969 Volume 6 Issue 1 Pages 48a
    Published: 1969
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    Download PDF (51K)
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