| 摘要 |
PURPOSE:To intermittently or continuously correct a fluctuation of a dust radio- active concentration output caused by a fluctuation of a half-life, and to realize the continuous dust monitor by providing a second radiation detector by separating it in the downstream direction of a filter paper transfer path by a prescribed distance from a first radiation detector placed in a dust collector, and allowing it to oppose the filter paper. CONSTITUTION:A second radiation detector 11 measures dust collection dust which is collected in a dust collection cycle of the previous time, and by its pulse output, a counting rate signal is obtained in a second scaler 12. By using a flow rate from a flowmeter 9 and an output of a first scaler 5, dust radioactive concentration in which the influenced by a fluctuation of a half life is corrected can be derived. In the case when a half-life of dust is shortened due to some state variation of a plant, it returns to a flat output by correcting an output of a second scaler 12 at a later time after a start time of a dust collection cycle 2.
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