Abstract:
PURPOSE:To operate the system continuously and fully automatically by making the system check its own sensitivity and zero point automatically and performing compensation and warning. CONSTITUTION:A shutter 28 is opened by a timer 48, and an approximately constant detected signal is outputted from an ionization chamber 10 which is irradiated by a reference radiation source 24. At the same time, the contact 44 is turned ON, the detected signal is compared 40 with a sensitivity reference value at the first time. If the sensitivity is deviated from the range of the specified value, the warning operation is actuated. Then, a switch 38 is turned ON by a check controller 50, the radiation detector 10 is turned to a zero check state, contact 46 is turned ON, and the zero check is performed. In a second comparator 42, the detected signal in the zero check state from the AD converter 20 is compared with the zero reference value. If the detected signal is deviated from the zero reference range, a specified warning is actuated.
Abstract:
PURPOSE:To enable simple sampling of radioactive dusts from multisystem, by a method wherein a filter paper is fed stage by stage to sample radioactive dusts in a concentrated manner from a multisystem sampling zone. CONSTITUTION:A plurality of dust flow ports 20 are aligned at equal intervals along a movement path 100. A filter paper retainer 22 adheres firmly to a long-sized filter paper 10 for securing in a position where it is located facing and opposite to the dust flow port 20 with the long-sized filter paper 10 inbetween. Sampling of dusts in air flowing in a suction pipe 28 is conducted in a condition that the dust flow port 20 adheres firmly to the filter paper retainer 22 with the filter paper 10 inbetween. Under a condition that the filter paper 10 is separated from the flow port 20 and it does not move, a solenoid valve 44 is opened, and a suction negative pressure is not applied to a dust feeding means 16. As a result, radioacdive dust does not leak from the dust flow port 20.
Abstract:
PURPOSE:To perform continuous full automatic operation by automatically updating the sensitivity compensating value which is computed from a signal detected at the time of irradiation of a reference radiation and the reference value corresponding to the reference radiation, and performing compensation. CONSTITUTION:During the time of normal monitoring operation, a contact 42 is turned ON or a contact 44 is turned OFF, and the converted 20 detected signal is outputted 22a after the sensitivity component value is compensated by a computing device 34. When a timer 46 reaches the sensitivity compensation time, the contact 42 is turned ON, an AND gate 56 is closed, a converter 20 is stopped, and a shutter 28 is opened. Then the detected signal in the ionization chamber 10 irradiated by a reference radiation source 24 is converted 20. In the case the monitored sensitivity is normal, approximately constant signal value is outputted to the sensitivity compensating circuit 22 from the converter 20. Since the contact 44 is turned ON at this time, the detected signal is stored in a register 36. Said detected signal and the reference signal are computed 40, and the result is supplied to the computing device.
Abstract:
PURPOSE:To calculate rapidly and automatically the density of a radioactive substance in the air by using the measured value of the radioactivity of filter paper adsorbing dust in the air and duct collection conditions recorded on the surface of the filter paper, by measuring the radioactivity of the filter paper at every dust adsorption part. CONSTITUTION:The monitor path consists of the 1st monitor path 10 and 2nd monitor path 12. Both monitor paths 10 and 12 are equipped with a roll of dust absorbing long-sized filter paper 14 in an interchangeable cassette including supply reel 16 and take-up reel 18. In the 1st monitor path 10, dust in the air is adsorbed and dust collection conditions are recorded; in the 2nd monitor path 12, radioactivity is measured and the dust collection conditions are read. Controller 44 calculates the density of the radioactive substance in the air from the radioactivity measured value and the dust collection conditions. The arithmetic result of controller 44 is outputted from output device 46 as radioactive substance density data.
Abstract:
PURPOSE:To form a device maintaining always a normal operation state by correcting zero adjustment and sensitivity by using switching automatically at predetermined times, a reference ray source control device and comparators. CONSTITUTION:The electric charge gathered at the current collecting electrode 12 of an ionization chamber 10 according to radiation dose is converted to voltage by an electrometer 14, and the voltage is digitized by an A/D converter 16. The digital signal is recorded and displayed with a display device 20, a printer 22 and an integrator 24 via a zero point adjusting circuit 100 and a sensitivity correctinng circuit 200. Zero point adjustment and sensitivity correction are carried out by driving flip- flops 44, 68 by the signal of a timer 42 and changing over switches. Select switches 30, 40 are turned on to input the zero adjustment output to a register 32, by which zero point is adjusted. A sensitivity correction value is outputted by the value of a register 58 obtained by irradiation with a reference ray source 46 and the reference value of a register 60 by opening a shutter 50. Zero point as well as the upper and lower limit values of sensitivity are applied to comparators 78, 80, and an alarm is emitted when out of these values. Thereby, the normal operation is continued.
Abstract:
PURPOSE:To perform accurate measurement of the amount of variation at all times by automatically updating the zero adjusting value at a specified interval, and adjusting the zero point of a detected signal by said zero point adjusting value. CONSTITUTION:Electric charges collected 12 in an ionization chamber 10 are converted to a voltage signal. ON and OFF operations of a switch 30 in a meter 14 is controlled by a switching signal from a zero point adjusting circuit 18. The output of an AD converter 16 is supplied to a register 36 when the switch 30 is turned OFF and supplied to a register 32 when the switch 30 is turned ON. The outputs of the registers 32 and 36 are operated 40, and the zero point is adjusted. When an FF 44 is inverted for a specified time by the output of a time 42 in a circuit 18, a contact 38 is turned OFF, and the supply of signal to the register 36 is stopped. When a signal is outputted Q from the FF 44, the switch 30 and the contact 34 are turned ON, and the detected signal under the zero checking state is supplied to the register 32, and the zero point adjusting value is updated.