著者

秋葉 澄伯 山田 裕司 床次 眞司 新倉 礼子 川畑 政治

出版者

鹿児島大学

雑誌

基盤研究(B)

巻号頁・発行日

2001

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1.鹿児島県内11市の死亡率を比較解析したところ、1980年代に桜島火山からの降灰量が著しく高かった垂水市で、女性の肺がん死亡率が最も高かった。2.活動性火山である桜島、霧島山に隣接した居住地域である鹿児島市、霧島町、垂水市の屋外におけるラドンとその子孫核種濃度を測定した。その結果、鹿児島市は3Bq/m^3、霧島町は5Bq/m^3であった、これは国内平均濃度5Bq/m^3と比べ有意差が見られなかった。しかし、垂水市内においては異例の高濃度事象(50Bq/m^3)を頻回に計測した。さらに、気象データを観測し、気象に関わる各種の変数がラドンとその子孫核種濃度に与える影響を検討した。その結果、ラドンとその子孫核種濃度と二酸化硫黄あるいは浮遊粒子状物質濃度との間には相関が見られなかったが、降灰量との間には相関が見られた。3.呼吸器疾患を持たない集団である一般対象家屋の屋内ラドンとその子孫核種濃度を測定した。その結果、鹿児島市は14.6Bq/m^3、牧園町は14.5Bq/m^3、垂水市は平均11(最低値5最高値24)Bq/m^3であった、これは国内平均濃度15.5Bq/m^3と比べ有意差が見られなかった。4.肺がん、慢性呼吸器疾患等を対象に質問票調査並びに家屋での屋内ラドンとその子孫核種濃度を測定した。その結果、家屋内の平均ラドン濃度は約10.8Bq/m^3と有意差は見られなかった。しかし、ある肺がん患者の家屋でラドン濃度が43Bq/m^3、その子孫核種濃度が90Bq/m^3と高い濃度を計測した。これらの放射能濃度を年間実効線量当量に換算すると約10mSvとなり、国際放射線防護委員会が勧告している一般公衆に対する年限度の1mSvに比べて非常に高い値となった。

著者

山田 裕司 小泉 彰 宮本 勝宏 稲葉 次郎

出版者

日本保健物理学会

雑誌

保健物理 (ISSN:03676110)

巻号頁・発行日

vol.29, no.3, pp.283-289, 1994 (Released:2010-02-25)

参考文献数

11

被引用文献数

1 1

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Decontamination Factors (DFs) of HEPA filter were measured against 239Pu oxide aerosols. Collection performance of HEPA filter media was investigated using monodisperse NaCl aerosols at various air flow face velocities. From the penetration curves the most penetrating particle size, MPPS, and the maximum penetration, Pmax, were obtained in each face velocity. The MPPSs at 0.8-11cm s-1 flow were not found in 0.3μm size range but in 0.1-0.15μm size range. The reciprocal of Pmax, which means the minimum of decontamination factor, DFmin, linearly increased with decreasing face velocity in a logarithmic paper. Experimental DFs against Pu aerosols in the MPPS range were nearly equal to the DFmin, and the others were always larger than the DFmin. This means that there are no differences between Pu and NaCl aerosols in terms of filtration. The DFmin estimated from the nonradioactive test aerosols is important for evaluating the performance of HEPA filters in the radiation protection field.

著者

石川 徹夫 安岡 由美 楢崎 幸範 床次 眞司 石井 忠 須田 博文 山田 裕司

出版者

公益社団法人 日本アイソトープ協会

雑誌

RADIOISOTOPES (ISSN:00338303)

巻号頁・発行日

vol.53, no.3, pp.133-140, 2004-03-15 (Released:2011-03-01)

参考文献数

21

被引用文献数

1 2

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Measurements of radon in water have been conducted by many investigators so far. While liquid scintillation counting is widely used for radon-in-water measurements in Japan, there are other available devices such as IM-fontactoscopes and atmospheric radon monitors with bubbling kits. In the present study, an intercomparison exercise was conducted for four devices using water samples with two different radon concentrations. The devices used are : a liquid scintillation counter, an IM-fontactoscope, a pulse ionization chamber with a bubbling kit and a radon monitor (which employs a silicon semiconductor detector) with a bubbling kit. As a result, there was a good agreement among the measured values for other devices than the IM-fontactoscope (differences were within±3%), The atmospheric radon monitors (with bubbling kits) could be useful for field surveys of radon-in-water, considering their portability. On the other hand, the values measured with the IM-fontactoscope deviated from other measure-ment values (47% for sample A and 22% for sample B) . The deviation might be caused by a calibration method for the IM-fontactoscope. Since the IM-fontactoscopes are used at some institutes in Japan even nowadays, it is necessary to check values measured with them for determination of radon-in-water concentrations.

著者

石川 徹夫 床次 眞司 米原 英典 福津 久美子 山田 裕司

出版者

日本保健物理学会

雑誌

保健物理 (ISSN:03676110)

巻号頁・発行日

vol.36, no.4, pp.329-338, 2001 (Released:2010-02-25)

参考文献数

21

被引用文献数

13 16 16

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To estimate dose from radon progeny, the effective dose per unit exposure to radon progeny (dose conversion factor, DCF) is needed. A dominant parameter related to DCF is the activity size distribution of radon progeny. In the present study, the DCF was calculated in the wide range of particle diameters (0.5-20nm [AMTD] and 20-5, 000nm [AMAD]), using a dosimetric approach. The calculations were based on a computer program, LUDEP, which implements an ICRP66 respiratory tract model. The calculated results showed that the DCF is sensitive to particle size distribution. The DCFs calculated for reference conditions in mines and homes were 13.7mSv WLM-1 and 14.3mSv WLM-1, respectively. These values were in good agreement with those reported in a few references. The DCF calculated in the present study is useful for the dose assessment of radon progeny in places that have different aerosol characteristics.

著者

小木曽 洋一 山田 裕司 飯田 治三 福津 久美子 福田 俊

出版者

Japan Health Physics Society

雑誌

保健物理 (ISSN:03676110)

巻号頁・発行日

vol.33, no.3, pp.308-313, 1998 (Released:2010-02-25)

参考文献数

15

著者

山田 裕司 宮本 勝宏 森 貞次 小泉 彰

出版者

Japan Health Physics Society

雑誌

保健物理 (ISSN:03676110)

巻号頁・発行日

vol.17, no.4, pp.461-467, 1982 (Released:2010-02-25)

参考文献数

11

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Collection performance of a HEPA filter and a new type filter which was recently developed for removing fine particles below 0.3μm was verified by using a laser aerosol particle counter in the particle size range from 0.12 to 0.42μm diameter in which the filter performance was not sufficiently clarified. Tested filter sheets were 14.5cm by 14.5cm in dimensions.DOP particles ranging from 0.12 to 0.17μm exhibited higher penetration of HEPA filter than DOP particles from 0.27 to 0.42μm by a factor of 20 at the standard face velocity of 2.4cm/sec. The penetration of HEPA filter was 6.6×10-4 for 0.12 to 0.17μm DOP particles, and that of the new type filter was 3.1×10-6.It was confirmed that overall system penetration of two HEPA filters in series could be described as the product of each stage penetration.

著者

石川 徹夫 床次 眞司 山田 裕司

出版者

公益社団法人 日本アイソトープ協会

雑誌

RADIOISOTOPES (ISSN:00338303)

巻号頁・発行日

vol.52, no.4, pp.203-209, 2003-04-15 (Released:2010-07-21)

参考文献数

17

被引用文献数

2 2

著者

山田 裕司 宮本 勝宏 小泉 彰

出版者

Japan Health Physics Society

雑誌

保健物理 (ISSN:03676110)

巻号頁・発行日

vol.21, no.4, pp.237-244, 1986

被引用文献数

3 1

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It is very important in a nuclear air cleaning system that HEPA (High Efficiency Particulate Air) filter is for reduction of releasing amounts of airborne radioactive particles. HEPA filter, by definition, has a minimum collection efficiency of 99.97% for 0.3μm particles. However, <i>DF</i> (Decontamination Factor), which is necessary for safety management, can not be directly derived from the efficiency. And the current standard defined for 0.3μm particles has no scientific justification, because it has been found that the most penetrating particle size through HEPA filter is not always 0.3μm.<br>In the present paper, a numerical experiment was made in order to estimate a relationship between <i>DF</i> and the efficiency. And new standard, in which the minimum <i>DF</i> is able to be easily obtained, was proposed. In the multistage filtration system, it was found that lower values of <i>DF</i> was possible to be experimentally indicated in the second and the third stages, even if the collection performance of the each filter is the same.

著者

山田 裕司 小泉 彰 宮本 勝宏

出版者

日本エアロゾル学会

雑誌

エアロゾル研究 = Journal of aerosol research (ISSN:09122834)

巻号頁・発行日

vol.11, no.1, pp.35-43, 1996-03-20

被引用文献数

7

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Aerosol penetrations through fibrous filters with pinholes were studied theoretically and experimentally. An equivalent thin filter layer (ETFL) model assuming a virtual filter layer was proposed to account for penetration through filters with pinholes. From one to thirty pinholes per filter were made on HEPA filter media using columnar pins of 0.195, 0.150 or 0.130 mm in diameter. Aerosol penetration through these filters was measured using monodisperse NaCl aerosols ranging from 0.05 to 0.3 μm in diameter at air flow face velocities of 0.00775, 0.0233 and 0.0698 m/s. Net penetration through the pinholes increased in proportion to the pinhole number and size. But there was no change in pressure drops across the filters. As a result of analysis based on the ETFL model, the layer thickness was estimated to range from 1/5 to 1/12 of the normal filter thickness. The predicted penetration curves were confirmed to agree well with the measured curves.

著者

山田 裕司 宮本 勝宏 小泉 彰

出版者

Japan Health Physics Society

雑誌

保健物理 : hoken buturi (ISSN:03676110)

巻号頁・発行日

vol.33, no.3, pp.294-297, 1998-09

著者

山田 裕司 福津 久美子 床次 眞司 卓 維海 孫 全冨 張 守志

雑誌

大気電気研究 (ISSN:02863405)

巻号頁・発行日

vol.64, pp.78-79, 2004-03-22