JIG FOR POSITIONING RADIOACTIVE SOURCE, AND METHOD OF INSPECTING INSPECTION OBJECT

PROBLEM TO BE SOLVED: To perform an inspection on a member even with a small frontage while accurately perceiving a region to be inspected.SOLUTION: After a guide tube 11 of a radiation source guide jig 10A is inserted into piping 1, the radiation source guide jig 10A is moved so that a linear light emitted from beam light sources 14, 14 disposed on tips 12a, 12a of side rods 12, 12 matches a marking M, M disposed on a weld zone 5. In this state, the radiation source guide jig 10A is moved by an actuator 9 so that intervals between the tips 12a, 12a on both side rods 12, 12 and an outer peripheral surface of the piping 1 are the same. By this operation, the tip 11a of the guide tube 11 is positioned against the center C of a pipe axis of the weld zone 5. A transmission tube 20 is inserted in the guide tube 11, and a radiation source 20a is exposed from the tip 11a. Then the weld zone is inspected on the basis of a radiation ray emitted from the radiation source 20a.