| Project/Area Number |
04680231
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Nuclear engineering
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| Research Institution | KOBE UNIVERSITY OF MERCANTILE MARINE |
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Principal Investigator |
MIYAKE Hiroshi Kobe Unv.Mercant.Marine, Fac.Mercant.Marine, Prof., 商船学部, 教授 (00031443)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAUCHI Tomoya Kobe Unv.Mercant.Marine, Fac.Mercant.Marine, Instruct., 商船学部, 助手 (40211619)
ODA Keiji Kobe Unv.Mercant.Marine, Fac.Mercant.Marine, Ass.Prof., 商船学部, 助教授 (40169305)
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1993: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1992: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | Radon / Thoron / Equilibrium-Equivalent / Passive Monitor / Daughter Concentration / alpha-energy Discrimination / CR-39 Track Detector / Electrostatic-Collection |
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| Research Abstract |
Simultaneous and discriminative measurement of the concentrations of radon, thoron and their daughters was performed using a passive monitor with CR-39 track detector. Etch pits on a detector were discriminated with their sized and shapes for alpha particle energy of 6.0MeV(^<218>Po, ^<212>Bi), 7.7MeV(^<214>Po) and 8.8MeV(^<212>Po). Discriminating capability was enhanced by use of a degrader mounted on the detector. Etch pits were automatically classified for their sized and shapes using a computer-aided counting system. Radon and thoron daughters were electrostatically collected onto the degrader surface in order to eliminate alpha particles impinged from the space near the detector surface with reduced energy. A cup for electrostatic collection was designed to prevent the alpha particles emitted from daughters attached on the cup wall and to obtain a flat distribution of daughters collected on the detector surface. This method was applied to the measurement of equilibrium-equivalent concentrations of radon and thoron in thoron-rich fields.
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