| 摘要 |
PURPOSE:To calculate the position of the sludge boundary surface for a radioactive substance storage tank and the radiation density thereof by raising a radiation detector elevationally along the tank and measuring and detecting the curved point of radiation quantity distribution curve. CONSTITUTION:While a radiation detector 3 is elevationally moved up and down in a guide tube 2 in a storage tank 1 by the operation of a constant speed elevator 5 to convert the detection signal therefrom to a radiation quantity rate through a converter 7, the relationship between the radiation quantity rate and the elevational position of the detector 3 is recorded on a recorder 8 as a radiation quantity distribution curve. The radiation density above or below the sludge boundary surface B in the boundary between the supernatant liquid W and the sludge S varies above 10<3> and the surface B is represented as a curved point M along the distribution curve. Accordingly, the point M can be discriminated simultaneously upon recording of the curve to thus immediately indicate the surface B. Thus, the radiation content density can be measured in the sludge S by measuring the distributed state of the curve and the energy of gamma rays.
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