Effects of the Protective Covers Against Radioactive Contamination of a GM Survey Meter Probe on the Counting Value

概要

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A GM survey-meter probe is usually covered with a polyethylene or poly (vinylidene chloride) sheet to prevent radioactive contamination. We investigated the effects of the thickness of these protective covers on the counting values of the survey-meter. A source was put on a detection face of the probe wrapped with the protective cover, and the counting values of the radiation from the source (14C, 35S, 45Ca, 51Cr and 32P) were measured. As the result, the decay rate of the counting values of 14C and 35S were high, that of 32P was low, and that of 45Ca was between these nuclides, in any thickness of these protective covers. On the other hand, in the case of 51Cr, the decay rate of the counting values with the poly (vinylidene chloride) cover was far higher than that with the polyethylene in any thickness. From calculation of transmittance of radiation from 51Cr, such difference in the decay rate between these covers was ascribed to the difference in constituent elements of these covers. Further, it was confirmed that the differences in the decay rates of the counting values by using the polyethylene sheets were available to identify certain of nuclides.
日本放射線安全管理学会の論文