Japanese Journal of Health Physics
Online ISSN : 1884-7560
Print ISSN : 0367-6110
ISSN-L : 0367-6110
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Volume 7, Issue 1
Displaying 1-4 of 4 articles from this issue
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  • Determination of Alpha Emitting Particle Size by the Autoradiography Using ZnS (Ag) Powder Screen
    Tsutomu OHATA, Mikio MURATA, Kiyori NAKATO, Futao NIINO
    1972 Volume 7 Issue 1 Pages 3-6
    Published: 1972
    Released on J-STAGE: February 25, 2010
    DOIhttps://doi.org/10.5453/jhps.7.3
    JOURNAL FREE ACCESS
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    The autoradiography using ZnS (Ag) powder screen was studied for estimating the particle size of alphaemitting dust collected on an air sampling filter paper.
    The sensitivities of three commercial emulsion films for the detection of plutonium particles were compared by using a ZnS (Ag) powder screen. The effect of particle size of ZnS (Ag) powder on the sensitivity was examined and also the change of apparent particle size distribution with exposure time was examined.
    As the result the following were obtained;
    1) The sensitivity of a polaroid film is about 10 times higher than that of the X ray films.
    2) The minimum detectable activity for the polaroid film is 0.01 dpm for the exposure of 168 hours, which is equivalent to the diameter of 0.25μ for a 239PuO2 particle.
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  • Estimation of Present and Future Levels of Excess Carbon-14 in the Environment from the Nuclear Tests (I)
    Six Reservoirs Model
    Tetsuo Iwakura
    1972 Volume 7 Issue 1 Pages 7-14
    Published: 1972
    Released on J-STAGE: February 25, 2010
    DOIhttps://doi.org/10.5453/jhps.7.7
    JOURNAL FREE ACCESS
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    The mathematical model with multi-compartments (reservoirs) and the computer program for the estimation of rates of change of the excess carbon-14 levels in environments caused by the successive nuclear tests to date are developed.
    A set of linear differential equations of the first order obtained from nonequilibrium conditions of carbon-14 are solved by Laplace transform. The procedure of the numerical calculations by the digital computer is presented. Input data for the computer are the amount of carbon-14 atoms in steady state in each reservoir, the exchange rate constants of carbon-14 between reserviors, and the explosion yields in megaton and dates of the nuclear tests. The calculated results are compared with the observed data. The reason of disagreements between calculated and observed concentrations of carbon-14 in several reservoirs is dicussed.
    The possible effect of a significant degree of direct exchange of carbon-14 between the troposphere and the deep sea reservoir in cyclic model is also examined by the computer-aided calculation. As a result of the comparison of the chain model with the cyclic one, it is found that by a slight modification of the chain model to the cyclic one, the calculated concentration of carbon-14 fits fairly well to the observed values.
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  • [title in Japanese]
    [in Japanese], [in Japanese], [in Japanese]
    1972 Volume 7 Issue 1 Pages 27-35
    Published: 1972
    Released on J-STAGE: February 25, 2010
    DOIhttps://doi.org/10.5453/jhps.7.27
    JOURNAL FREE ACCESS
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  • Intercomparison of the Accuracy of Dosimetry Systems Used in the Different Facilities
    Hatsumi TATSUTA, Kasuyuki MORIUCHI, Akira KATOH, Iwao YAMACHI, Ken MAT ...
    1972 Volume 7 Issue 1 Pages 37-41
    Published: 1972
    Released on J-STAGE: February 25, 2010
    DOIhttps://doi.org/10.5453/jhps.7.37
    JOURNAL FREE ACCESS
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    Many kinds of dosimeters are being used to evaluate the personal exposure doses in nuclear facilities, industrial plants, and hospitals. This report describes the accuracy and the error in measuring external doses by a variety of dosimeters in different facilities. The standard irradiation of dosimeters was carried out at the Electrotechnical Laboratory of the Ministry of International Trade and Industry, and the measurement of doses was done by the film-service section in each facility.
    The precision of both film badge and glass dosimeter systems under the best condition was about 3% standard deviation in the range of dose from 100mR to 500mR. The film badge was more precise than the glass dosimeter at lower dose (less than 100mR), whereas the glass dosimeter gave better results at higher dose (more than 1000mR). Only two types of thermo-luminescent dosimeters were tested, therefore, the precision of the thermo-luminescent dosimeter system was not given clearly in this report. The study on the accuracy of this system is continuing.
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