An Assessment of Radioactivity Levels of 210Pb and 40K in Tobacco and Radiation Exposure from Smoking

No research has been conducted on the radiation influence of tobacco on the alimentary system, although there have been some previous works on the respiratory system. In this study, the radioactive concentrations of 210Pb and 40K in a cigarette sample were first measured. The transfer factors of the nuclides from tobacco into smoke and solution (saliva and/or alcohol) were then examined. Moreover, the radiation doses from smoke inhalation were also evaluated. The radioactive concentrations of 210Pb and 40K in the cigarette tobacco were 0.01 and 0.3 Bq/cigarette. Since this 210Pb activity and the 210Po activity previously reported for the same sample were comparable, it can be concluded that there was a radioactive equilibrium between the 2 nuclides. The observed transfer factor of 210Pb (12%) into smoke was almost the same as that of 40K (15%), whereas the reported value for 210Po (60%) was significantly higher. The radiation doses due to inhalation of cigarette smoke varied from organ to organ, depending on the organotropic properties of the nuclide. For example, the kidneys, respiratory tract, and spleen showed relatively high doses from 210Pb and 210Po. The leaching rates indicated an inconsistent tendency related to solution types. This result could suggest that alcohol drinking, which is common in smokers, does not especially enhance the leaching characteristics

岡山大学における核燃料物質の安全管理のための劣化ウランと天然ウランの鑑別について

In Japan, the Law for the Regulation of Nuclear Source Materials, Nuclear Fuel Materials and Reactors (Regulation Law) controls the nuclear fuel materials such as thorium (Th), uranium (U) and plutonium (Pu). Under the Regulation Law, all related materials and reactors are needed to register to the Government. In Okayama University, many nuclear fuel materials, mainly uranium compounds, are registered and stored in 11 departments, separately. Discrimination between depleted uranium and natural uranium is important for the observance of the Regulation Law and the safety management of the nuclear fuel materials in the Okayama University. However, the discrimination of the two kind of uranium has poorly analyzed. In this study, we analyzed several uranium compounds by using γ-ray spectrometry to determine whether the depleted uranium or not

Rationalization of measures to protect the working environment in radiation controlled areas from the perspective of the relationship between surface and airborne contamination

放射線管理区域において業務従事者の放射線防護が正確に実施されていることを確認するために放射性同位元素の環境測定が行われている。しかし，実際の測定においては，濃度が低いなど実測困難な場合が多いこと，多くの人手と経費を要していることから，より合理的な測定の実施ができないかということについての検討が期待されている。このため本総説では，まず大学などの放射線管理区域における作業環境測定方法の現状についてまとめた。次に，放射線管理区域の床，作業台などにおける放射性同位元素の表面汚染と空気汚染に着目し，汚染粒子の移行など表面汚染と空気汚染の関係機構について，また，スミア法や直接測定法などの各種表面汚染測定法の汚染採取効率などを指標とした特性とこれら測定法の改良の試みについてまとめた。さらに，実際の作業場所において，作業内容，換気，表面材料などが表面汚染と空気汚染の関係に及ぼす影響について，その検討例を紹介した。得られた知見をまとめるとともに，測定箇所・測定頻度の適性化やそれぞれの測定箇所に適した測定法の選定など作業環境測定の一層の合理化に向けて，今後どのような検討が必要なのかについて提案した。In radiation controlled areas, measures have been taken to assess the radiation dose to workers, but these efforts are limited due to high labor and cost factors in extremely low dose radiation controlled areas. And so they have been expected to be rationalized. Therefore, we first reviewed the present conditions of these working environment measurement and elucidated the relationship between surface and airborne contamination in radiation controlled areas. Second, we reviewed the qualities of several surface contamination measurements such as smear test and possibilities for their improvement. As a result, we developed some future programs for rationalization of the working environment measurements, for example, an algorithm for selecting the proper surface contamination measurement for each measurement area based on the conditions specific to that area

Basic study on the effects of the archeological investigation and the construction work on the environmental radiation

In this paper, we investigated how the excavation of ruins and the construction work affected the environmental radiation in the Shikata campus of Okayama University (S-campus). The environmental radiation was steady in the S-campus until 1997, but began to change since 1998, while the ruin's survey and the construction work started frequently after 1998 in the S-campus. In general, the soil and the concrete include the natural radioisotope (uranium series and thorium series, etc). When ruins are surveyed, it is necessary to move a large amount of the soil. In addition, a large amount of the concrete is used for the construction work. To measure the environmental radiation, the monitor posts were set up on the east and west sides of the building of the Radioisotope Center (RIC). We sampled the soil in the container in each place. We used the high-purity germanium detector to analyze them. The monitor posts showed the difference in the in-air dose rate in each place in the S-campus. The in-air dose rate at the east side of the RIC was higher than that at the west side. The result of analysis showed that the soil includes the (40)K at the east side. While the specific activity of the 40K was 0.849Bq/g at the east side, the (40)K was hardly detected in the soil at the west side. The each soil included the 214-lead and 214-bismus ((214)Pb, (214)Bi), however, there was no significant difference in the specific activity of the each soil. The concrete included (40)K, whose specific activity was 0.492Bq/g. It was suggested that the change of the environmental radiation was attributed to radon and its daughter nuclides in the soil rather than the radiation from the concrete in the buildings

Approach on the simple and easy method for measurement of airborne radioactive iodine((125)I)

放射性ヨウ素（(123)I，(125)I，(131)I）は飛散しやすいなどの特性があり，他の放射性核種に比べ慎重な取扱いが求められている。また，この核種の空気中濃度限度は非常に低く，濃度測定には大量の空気を吸引しなければならず，そのための装置も大掛かりとなる。このため，本研究では，活性炭ろ紙をホルダにセットし，これを注射器に取り付けた簡易な装置を考案・試作し，空気中の放射性ヨウ素濃度を簡便に測る方法について実験・検討した。その結果，まず放射性ヨウ素にNa(125)Iを用いた場合の捕集効率は44.5％であることが分かった。次に，50mℓ注射器を用いて1ℓの空気を吸引・ろ過し，Nal（Tl）ウェルタイプシンチレーションカウンタで30分間放射能を測定した場合，本装置では空気中濃度限度の2.12倍の濃度の(125)Iが測定可能であり，気体状ヨウ素の漏れを防いで捕集効率を94.3％以上に上げることができれば，空気中濃度限度まで測定可能であることが示された。このため，本法は簡便かつ安価に異常を検知する測定方法として利用できるのではないかと考えられた。Radioactive iodines (iodine-123, -125, -131) are used as the marker in vitro test, nuclear medicine and so on. It is necessary to handle them carefully, because radioactive iodines scatter easily. As air concentration limits of radioisotopes are very low levels, we should prepare the measurement technique using a large-volumed aspirator and large-scaled equipments. In this study, we examined the simple and easy method for the measurement of concentration of airborne radioactive iodines. We designed and manufactured the simple set of holder and charcoal filter connected to hypodermic syringe. The collecting efficiency of airborne iodine-125 by this system was 44.5%. In the case of that a liter of the air was filtered by this system connected to 50 mℓ syringe and counted the radioactivity for 30 minutes by the NaI(Tl) well-type scintillation counter, It is indicated that iodine-125 of air concentration limit can be measured

Effects of some physical conditions on leaching rate of radon from radioactive minerals originating from some hot springs

In order to determine the best physical conditions for leaching more radon from minerals into water, we measured the leaching rate of radon from radioactive minerals under the conditions of some different grain sizes and water temperatures. Water temperature affected the leaching rate of radon although the grain size did not significantly affect it. Furthermore, we proposed ultrasonic irradiation to the mixture of a mineral and water as the method of leaching more radon. Ultrasonic irradiation was efficient to leach more radon from the mineral soaked in water because of ultrasonic cavitation.</p

Radioactivity and radon emanation fraction of the granites sampled at Misasa and Badgastein

The chemical composition was analyzed and the radioactivity, radon exhalation rate and emanation fraction were measured to investigate the characteristics of the granites sampled at Misasa and Badgastein, world famous for radon therapy. The Misasa granite was probably composed of quartz, albite and microcline. The Badgastein granite was probably composed of quartz and muscovite. The radon exhalation rates and emanation fractions of the Misasa granite were much higher than those of the Badgastein granite, regardless of the Ra-226 activity concentrations

Volume Reduction by the Incineration of the Combustible Radioactive Solid Samples from Radioisotope Usage at the Utilization Facility : Estimation of the Distribution of Low Energy β-Emitter Using the Imaging Plate

We want to establish a system of volume reduction by the incineration of the combustible radioactive solid wastes from radioisotope usage at the utilization facility. We have been performing experiments using an experimental incineration system to examine the distribution of radionuclides during incineration and to collect basic data. To reproduce the realistic conditions of incineration of low-level radioactive wastes in an experimental system, we adopted new incineration methods in this study. Low level radioactive samples (LLRS) were set up in a mesh container of stainless steel and incinerated at high temperature (over 800•Ž) generated by two sets of high calorie gas burners. Low energy ƒÀ-emitters 35S, 45Ca, 33P, and a high energy ƒÀ-emitter 32P were used for the experiment. Their translocation percentages in exhaust air and dust were estimated using the Imaging Plate. Distribution of radionuclides during the incineration was similar to that estimated by conventional methods by our study or to that reported in incineration of liquid scintillation cocktail waste. We concluded that the use of the Imaging Plates is a simple and reliable method for estimation of the distribution of low energy ƒÀ-emitters in incineration gas and ash