| 摘要 |
PURPOSE:To improve measuring accuracy by supplying sweep gas to lead enriched sample gas into a detector, thereby enabling positive measurement even in the case of the concentration of the sample gas being low. CONSTITUTION:Sample gas from radioactive material handling facilities flows into a dehumidifying tower 11A from a sample gas inlet through a valve 10A, and the ordinary temperature tower 11A removes moisture. An adsorption tower 13A adsorbs object gas from the sample gas dried at the tower 11A. In this case, the adsorption tower 13A is cooled by a temperature regulator 14A to increase the adsorption of the object gas. The passage time can be thereby enlarged to increase an enrichment ratio. After adsorbing the object gas for the fixed time, the valve 10A is closed and a valve 15A is opened, and the adsorption tower 13A is heated by the regulator 14A for the desorption of the adsorbed object gas. Sweep gas is then let flow from the valve 15A to lead the enriched sample gas into a radiation detector 17 through a valve 16A. A measuring appratus 18 then measures the radiation concentration from a detected (17) output signal.
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