| 摘要 |
PURPOSE:To contrive to measure without segmenting a radioactive contaminated surface by grinding the radioactive contaminated surface locally, collecting ground pieces and a blast material in a container, and measuring the radioactivity of the container by a gamma-ray detector and finding the radioactivity concentration. CONSTITUTION:The container 10 where the mixture of the blast material 14 and ground bodies 24 are collected is detached from a sealed duct 16 and the opening part 10a of the container 10 is closed with a lid. Then the container 10 is mounted on the gamma-ray detection surface on the gamma-ray detector. Then a shield box surrounds the entire area of the container 10 to lower the background of the atmosphere in the shield box. Then the gamma-ray detector is put in operation to measure gamma-rays emitted from the container 10. The radioactive contamination concentration is found from a specific expression based upon the layer height of the blast material 14 and ground bodies 24 collected in the container 10, the total counting rate by the gamma-ray detection part, and the surface area of a measurement area. Consequently, the radioactive contamination density of a wall surface 18a can be measured without segmenting the contaminated surface.
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