| 摘要 |
PURPOSE:To perform accurate BG(background) compensation using a measuring system and an absorption collecting system which together form one system to enable accurate measurements of dust radioactive concentration to be made by incorporating a sequence for measuring and collecting the background every time a dust collecting filter is replaced and transferred. CONSTITUTION:A dust-collecting roll filter 6 is transferred and newly set and accurate BG including the contamination of a dust collecting portion 3 is measured 7 with no radioactive dust included. Next, dust in air is sucked 4 into the collecting portion 3 from a suction pipe 1 via a valve 2, and the dust collected on the filter 6 is measured using a detector 7 capable of measurement while discriminating between alpha-and beta-rays, and a value measured by the detector 7 is corrected using a previously measured value of BG. Dust radioactive concentration is constantly measured 7 even during collection and measurement, and when the radioactive concentration is in excess of an abnormal reference value, an alarm for abnormality is issued using a control and monitoring board 9. Thus accurate BG measurements and alpha-ray spectrum analyses can be made using only the measuring system and the absorption collecting system that together form one system.
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