| 摘要 |
PURPOSE:To determine the deposited radioactivity and solution type radioactivity or deposited radioactivity and gaseous radioactivity in a pipe without destruction by scanning and measuring gamma rays emitted by the radioactivity in the piping from outside by a gamma-ray detection system which has a collimator window. CONSTITUTION:The gamma-ray detection system 8 which has its detector 7 covered with a shield body 6 having the rectangular collimator window 5 is set at the center part by the piping 9 which is contaminated internally with the radioactivity. Then, the emitted gamma rays are scanned and measured while the detection system is varied in angle 10 around the front surface of the detector 7 as an axis, and gamma rays are counted at intervals of respective measurement angles. The number of gamma rays in each state which reach the detector 7 is calculated from the distance 14 from the axis to the detector, the internal diameter 15 and external diameter 16 of the pipe, radiation absorption coefficients of the piping, water, and gas, and the longitudinal width 17 and thickness 18 of the window 5 on condition that the deposited radioactivity 11 and solution type radioactivity 12 or gaseous radioactivity 13 in the pipe are distributed uniformly.
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