| 摘要 |
PURPOSE:To measure the trace of radioactive substance in a gas, by a method wherein a compressable and capacity reducible fibrous filter with a large adsorption area is used to absorb a large amount of radioactive substance and then, compressed and reduced in the capacity to measure the radiation dose thereof. CONSTITUTION:In a ventilation air conditioning system duct 1, a bypass piping line 2 is provided to trap radioactive substance bypassing and air of the ventilation air conditioning system duct flows into the bypass piping line 2 to pass through an active carbon fiber filter 4. At this point, radioactive iodine in the air is adsorbed and trapped by the active carbon fiber filter 4 and then, the air returns to the ventilation air conditioning duct. Thus, the radioactive iodine in the air is trapped. Then, the active carbon fiber filter 4 finished with the trapping of the radioactive iodine is compressed and reduced in the capacity to about one over one thousand by a proper method. The active carbon fiber filter 4 thus treated is subjected with a germanium detector 9 to measure the radiation dose.
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