RADIATION MONITORING DEVICE

摘要

A radiation monitoring device comprises a radiation monitor and a test unit for testing the radiation monitor. The radiation monitor includes a radiation detector and a measurement unit. The test unit includes a test pulse generator and a test pulse controller. The measurement unit includes a counter circuit, a computing part that computes a count rate with the standard deviation kept constant, an input switching circuit. When a test mode is selected in the radiation monitor, the test pulse controller changes the repetition frequency of test pulses in a step-function manner to the same repetition frequency of a start count rate specified as reference, replaces a count rate in the computing part at current computing cycle with the start count rate, switches the input switching circuit to the test pulse input at next computing cycle to start the test, and then finishes the test after a predetermined time elapses.

主权项

1. A radiation monitoring device comprising:
a radiation monitor that measures radiation; and a test unit that tests the radiation monitor,wherein either a measurement mode or a test mode is selectable, and the test mode is selected at a test and the measurement mode is selected ordinarily at radiation monitoring,the radiation monitor including:
a radiation detector that detects radiation and outputs detection signal pulses; and a measurement unit that receives the detection signal pulses and measures a count rate,the test unit including:
a test pulse generator that generates test pulses; and a test pulse controller that controls a repetition frequency of the test pulses output from the test pulse generator and switches an input of the measurement unit,the measurement unit including:
a pulse amplifier circuit that shapes waveform of the detection signal pulses and amplifies height of the detection signal pulses, and removes high frequency noise superimposed on the detection signal pulses; a noise discriminating and removing circuit that discriminates and removes a noise pulse from the output pulses of the pulse amplifier circuit, and outputs digital pulses; a counter circuit that receives and counts the digital pulses; a computing part that receives count values output from the counter circuit and computes the count rate with a standard deviation of the count values kept constant; a display and operation part that displays an output of the computing part and receives an operation for the measurement unit; and an input switching circuit that switches an input of the pulse amplifier circuit to either one of an input of the detection signal pulses, neutral with no input, or an input of the test pulses under control of the test pulse controller via the computing part,wherein when the test mode is selected and a test item is chosen, the test pulse controller switches the input switching circuit to neutral; then changes the repetition frequency of the test pulses in a step-function manner to the same repetition frequency of a start count rate set arbitrarily or specified as a reference according to the test item; and replaces a count rate in the computing part at current computing cycle with the start count rate set arbitrarily or specified according to the test item; then switches the input switching circuit to the test pulse input from neutral at next computing cycle; starts the test; and then finishes the test after a predetermined time elapses.