| 主权项 |
1. A radiation monitor comprising:
a gas flow path in which a sampling solenoid valve, a purge solenoid valve, a pump, and an exhaust solenoid valve, each being operated by an AC electric power, are provided, and a sampling gas suctioned from a sampling point is circulated; a flow sensor installed in said gas flow path; a pressure sensor installed in said gas flow path; an AC control section in which the AC electric power is supplied to said sampling solenoid valve, said purge solenoid valve, said pump, and said exhaust solenoid valve, and when a flow path abnormality signal is received, said sampling solenoid valve, said purge solenoid valve, and said exhaust solenoid valve are controlled to be closed and said pump is stopped; a DC control section which is operated by a DC electric power in which the AC electric power supplied from said AC control section is converted, and outputs the flow path abnormality signal in the case where a measured value of said flow sensor or a measured value of said pressure sensor is lower than a set value; a detection unit which detects radiation to be released from the sampling gas suctioned to said gas flow path, and outputs a detection signal; and a measurement unit which measures the detection signal outputted from said detection unit, and outputs radioactivity concentration, wherein said AC control section outputs an AC power source instantaneous power failure detection signal to said DC control section when a decrease in AC voltage is detected; said DC control section measures a duration time of the AC power source instantaneous power failure detection signal when the AC power source instantaneous power failure detection signal is received from said AC control section, and outputs an instantaneous power failure restart signal to said AC control section if the AC voltage is restored within a time shorter than the set value; and said AC control section performs switching control from close to open of said sampling solenoid valve, said purge solenoid valve, and said exhaust solenoid valve, and restarts said pump after a constant time when the instantaneous power failure restart signal is received from said DC control section. |
