保健物理

固化体中放射性核種の溶出に関する研究

多孔性媒質中における拡散と有効拡散係数の測定法に関する一考察

岩井重久, 井上頼輝, 寺島泰

1968 年 3 巻 2 号 p. 261-272
発行日: 1968年
公開日: 2010/03/15

DOIhttps://doi.org/10.5453/jhps.3.261

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The rate of the elution of radionuclides from solidified wastes depends mainly on the dissolution at the surface of the solidified wastes and the diffusion process in the solidified body. Concerning the later process, several methods to determine the effective diffusion coefficients were reviewed and newly developed theoretically in this study. It was revealed that the coefficients representing the diffusion of radionuclides migrating in the solidified wastes can be obtained through measurements of radionuclides which were leached out from a solidified body, with limited or unlimited length, into a finite volume of water.

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中国核実験による放射性降下物の観測

河合広, 本田嘉秀, 森嶋弥重, 古賀妙子, 木村雄一郎, 西脇安

1968 年 3 巻 2 号 p. 273-279
発行日: 1968年
公開日: 2010/03/15

DOIhttps://doi.org/10.5453/jhps.3.273

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We have observed properties of radioactive fallout originated from the first, the second, the third, the fourth and the fifth Chinese nuclear explosions. The differences in gross beta-activities, activities per unit volume and their particle sizes of highly radioactive particles are discussed with relation to the differences in burst conditions among the five explosions from which they originated.
It was found that radioactivities of the highly radioactive particles were roughly proportional to their volumes. The differences in the radioactive decay rates of highly radioactive fallout particles were found in connection with their colors.
From the results of decay characteristics of gross beta-activities and γ-ray spectra of fallout samples, it was found that the contribution of radioactivities of ²³⁹Np in samples from the fifth Chinese explosion was larger than that from the third Chinese explosion.
In comparison between the γ-ray spectra of highly radioactive fallout particles from the third and the fifth Chinese explosions, the particles from the third Chinese explosion were enriched in ⁹⁵Zr+⁹⁵Nb and impoverished in ¹⁰³Ru, while on the particles from the fifth Chinese explosion, the reverse of phenomenon above mentioned was observed.

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セルローズ・アスベスト濾紙に捕集されたα放射性浮遊塵埃の測定

α線スペクトロメトリーと濾紙内部への放射性塵埃の浸透

黒田捷雄

1968 年 3 巻 2 号 p. 280-287
発行日: 1968年
公開日: 2010/07/27

DOIhttps://doi.org/10.5453/jhps.3.280

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In measuring α ray spectra of radioactive airborne dust collected on a filter paper, the presence of α emitters to be detected is masked out by Rn and Tn daughters in atomosphere. Contributions of Tn daughters to α ray spectra of airborne radioactive materials were evaluated for two types of cellulose asbestos filter paper, HE-40 (Toyo) and HV-70 (Honing Worth & Vose), employed in routine air sampling, using the TMC 1024 pulse height analyzer with a silicon semiconductor detector. The distribution was also examined by α counting of thin stripped fragments of the filter paper, and was found to be exponential. On the basis of the results obtained, the collection efficiency of HE-40 and the absorption of α particle in the filter paper are discussed.

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トリチウム化重水のポリマーフィルム透過率測定と防護具の安全性評価

加藤仁三, 大内正房

1968 年 3 巻 2 号 p. 288-294
発行日: 1968年
公開日: 2010/03/15

DOIhttps://doi.org/10.5453/jhps.3.288

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In handling radioactive materials, various kinds of protective clothing made of polymeric films are employed for the protection of radioactive contamination. The permeation rate of the tritiated heavy water and its vapour through polymeric film, such as PVC, polyethylene, rubber was measured by using an ionization chamber with a vibrating reed electrometer.
On the basis of the results obtained, internal exposure of the person wearing the protective clothing is evaluated and discussed.

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体内汚染管理に関する情報理論的考察

安斎育郎, 吉沢康雄

1968 年 3 巻 2 号 p. 295-303
発行日: 1968年
公開日: 2010/03/15

DOIhttps://doi.org/10.5453/jhps.3.295

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The authors emphasized in the former paper that the measured values in the field of radiological protection are inevitably concerned with the uncertain factors which can never be dissolved by mere improvement of measurement techniques. A concept of “Entropy”popularly used in information theory was introduced in this paper in order to give a quantitative estimation of the uncertainty which appears in the problem of internal contamination measurement. Body retention of the radioactive contaminant after a single intake changes with time according to the physical decay and biological elimination. Hence we have uncertainty in case of estimating the initial amount of contamination from a single value of one-point sampling and measurement. When the detected body burden is q (μCi), the probability with which the initial intake Q_o (μCi) may have been over the predecided reference value q_o (μCi) was given as follows,
p (Q_o≥q_o) =1-T_eff/τlog₂q_o/q
where τ is the interval of measurement and T_eff is the effective half life. Apparently,
p (Q_o<q_o) =T_eff/τlog₂q_o/q
The authors also gave a graphical presentation of the entropy and discussed the effectiveness of internal contamination sampling program.

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⁶⁰Co, ⁵⁸Coによる傷口汚染の一事例

矢部明

1968 年 3 巻 2 号 p. 304-306
発行日: 1968年
公開日: 2010/03/15

DOIhttps://doi.org/10.5453/jhps.3.304

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