QUANTITATIVE DETERMINATION METHOD FOR RADIOACTIVE SUBSTANCE IN INSIDE OF STRUCTURE BY MEASUREMENT OF gammaRAYS

摘要

PROBLEM TO BE SOLVED: To provide a method in which a radioactive substance can be quantitatively determined by usingγrays without destroying or decomposing a structure in a complicated shape even when the radioactive substance existing in the inside of the structure does not radiate neutron rays so much. SOLUTION: A known radioactive substance whichγrays exists in a plurality of regions 2a, 2b in the inside of a structure whose shape and material are known. In this case, the regions in which the radioactive substance exists and the amount of the radioactive substance in the regions are quantitatively determined on the basis of a plurality of measured results of the intensity of theγrays measured through a plurality of measuring devices 30 to which collimators 10, 20 having differentγ-ray incident areas are attached and on the basis of the theoretically calculated result of the intensity of theγrays at a time when the rays from the radioactive substance in a unit mass reach the plurality of measuring devices 30 to which the collimators 10, 20 are attached.