| 摘要 |
PURPOSE:To improve accuracy and detecting speed by computing beta ray amount from the output difference between the detector reacting with both of beta ray and gamma ray and the detector reacting with gamma ray only and detecting the failure of atomic reactor system with employment of attenuation characteristics of beta ray. CONSTITUTION:Radiation detector 21a detects gamma ray and beta ray with piezo-electric element 11. Radiation detector 21b detects gamma ray only by shielding the opening 16 of the detector 21a with metal. Detecting values of the detectors 21a and 21b are amplified with amplifiers 22 and 23 and applied to ratemeter 24 and counter 25, producing direct current with ratemeter 24 to enter into the comparator circuit 26. Here, the outputs of both ratemeter 24 are compared, when the difference thereof shows higher than a certain allowable range, the power of alarm circuit 27 is produced to ring the alarm.
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