| 摘要 |
<p>PROBLEM TO BE SOLVED: To detect a defect position not only in terms of a plane but also in a depth direction, by detecting the amount of radiation that is emitted from a radiation source and is transmitted through an inspection target by a detection part, then reversing the positions of the radiation source and a detector, and then detecting the amount of radiation again, and hence comparing detection results before and after the position change. SOLUTION: A radiation source 1 accommodates a radiation substance in a radiation source accommodation container with an opening only at one side. Cesium 137 or cobalt 60 is preferable as the radiation substance of the radiation source 1, and the amount of application of radiation is set to a small amount of prescribed value or less. A detector 2 consists of nine detection parts (K1-K9) that are aligned in three rows vertically and horizontally, and is arranged so that a detection part being positioned at the center is located at the front of the radiation source 1 while sandwiching the inspection target. Each detection part is provided with a scintillator consisting of a crystal body of sodium iodide and a photomultiplier. Radiation through the inspection target is detected at each detection part, then the positions of the radiation source 1 and the detector 2 are reversed for examining the amount of attenuation of radiation, and the detection results are compared before and after the position change.</p> |
