| 摘要 |
<p>PROBLEM TO BE SOLVED: To measure a depth distribution of radioactive cesium efficiently with high accuracy.SOLUTION: An underground radioactivity measuring apparatus includes: an inner tube 4 storing therein a plurality of radiation detectors 2 in multiple stages via shield members 3, and having a beta ray shield function; an outer tube 5 arranged around the inner tube 4; a plurality of first measuring windows 4a formed in a depth direction of the inner tube 4; a plurality of measuring windows 5a formed in a depth direction of the outer tube 5 to correspond to the respective radiation detectors 2; and drive means for moving the inner tube 4 relatively to the outer tube 5, thereby making the first and second measuring windows 4a and 5a into an alignment or a non-alignment state. If the first and second measuring windows 4a and 5a are in the alignment state, the radiation detector 2 measures beta rays and gamma rays in the ground. If the first and second measuring windows 4a and 5a are in the non-alignment state, the radiation detector 2 measures gamma rays in the ground and obtain measurement values of the beta rays from measurement values of the gamma rays, thereby measuring a depth distribution of an underground radioactive matter.</p> |
