JPH06100655B2 - Continuous dust monitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a continuous dust monitor capable of continuously measuring the radiation concentration in a fluid around a nuclear reactor, for example.

(Prior Art) Conventionally, there are a continuous dust monitor (online) and a dust monitor for concentration measurement (offline), which are described below, as examples of dust monitors capable of measuring the radiation concentration around a nuclear reactor.

The continuous dust monitor is intended to monitor plant abnormalities by detecting leaks in sampling pipes. As shown in FIG. 5, the air in each place of the nuclear power plant is sucked by a suction pump P through a sampling pipe L provided for sampling, and each sampling pipe L
, VN provided in the middle of the switch are sequentially switched by the valve selector V to collect dust on the filter paper F continuously fed by the filter paper feed mechanism FD, which is then detected by the radiation detector DT. It is configured to monitor at. In addition, S is a sequencer for controlling each of the suction pump P, the filter paper feeding mechanism FD, and the piping valves V1 to VN, and M is a rate meter (counter) that outputs an alarm signal or a recording signal based on the detection result of the radiation detector DT. is there.

A continuous dust monitor with such a configuration can be used as a radiation detector DT.
Since it is equipped with a rate meter M and an absolute value, it is not particularly necessary to measure the radiation concentration as an absolute value, and it suffices to know the relative change from the radiation measurement level under normal conditions, and one location for a long time. It has the advantage of not having to sample and measure the average concentration.

On the other hand, the dust monitor for concentration measurement measures the radiation concentration in the air for judging suitability for human working environment, and is configured as shown in FIG.
FIG. 6 shows a suction pump for directly collecting dust in the air to the fixed type dust collecting filter paper FF without providing a monitor at each fixed point in the nuclear power plant and providing the sampling pipe L as shown in FIG. The dust is collected by P. The filter paper FF thus collected and collected is measured by an off-line radiation measuring instrument (not shown) by manual analysis, and the dust concentration at the sample point is calculated manually by the integrated flow meter FQ. Is. PI is a pressure gauge for measuring the pressure of the air sucked by the suction pump P. The continuous dust monitor in FIG. 5 and the dust monitor for concentration measurement in FIG. 6 are both installed at the measurement posts of the nuclear power plant.

Since the dust monitor for concentration measurement having such a configuration does not have the sampling pipe L, it has an advantage that there is no measurement error due to dust deposition.

(Problems to be Solved by the Invention) However, the continuous dust monitor shown in FIG.
Both the DT and the rate meter M are shared by one channel, and the sampling ring L and the piping valves V1 to VN are arranged on the input side of the dust collecting unit in correspondence with the points to be measured. Therefore, it has the following drawbacks.

(1) Sampling pipes L and pipe valves V1 to VN must be arranged between each sampling point 1 to N and the filter paper F of the filter paper feed mechanism FD, and the deposition loss of dust by each sampling pipe L Therefore, it is difficult to evaluate as a dust concentration measurement.

(2) The measurement time interval of one sampling point (measurement point) to be measured is normally every 4 hours (12 places x 20 minutes = 24).
0 minutes), the response delay is large, and it is not suitable as an atmosphere monitor with changes.

(3) Measurement results are displayed intermittently and continuous recording is not possible.

Moreover, the dust monitor for concentration measurement shown in FIG. 6 has an independent dust collecting unit for each point to be measured, and does not have any functions such as a radiation detector, a rate meter, and a concentration calculation unit.
Since it is an off-line system, it has the following drawbacks.

It is necessary to manually analyze the measurement results with an off-line radiation measuring instrument.

Only average data can be obtained once every 8 hours, and instantaneous data cannot be obtained.

Even if an abnormality such as a failure occurs, it can only be understood on site.

Therefore, the present invention is capable of continuously measuring the radioactivity concentration contained in dust without interruption, does not require a sampling pipe for sampling, has no deposition in the sampling pipe, and improves the measurement accuracy. It is an object of the present invention to provide a continuous dust monitor that can be easily operated by changing (moving) or adding sampling points, and that does not stop the function of the entire system even if a dust sampler at one location fails, and can be operated separately.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention is arranged corresponding to a point to be measured, and a measurement fluid is continuously introduced into a flow path by a fluid suction means. Which is capable of being introduced into the flow passage, and when the fluid is introduced into the flow passage, while filtering the dust contained in the fluid by the filter body provided in the mechanism capable of continuously feeding, the fluid introduced into the flow passage A plurality of samplers having a flow meter for detecting the flow rate, a plurality of radiation detectors respectively detecting the radiation dose of dust filtered by each filter of each sampler, a radiation detector for each sampler and the flow rate It is provided with a calculator for inputting the detection signal from the meter and calculating the radiation concentration, and a display for displaying the calculation result of this calculator.

(Operation) According to the present invention, the dust contained in the fluid is filtered by the filter body at each point to be measured, and the radiation dose contained in the dust and the fluid flow rate passing through the filter body are detected. A dust sampler is constructed so that the radiation dose and fluid flow rate detection signals from each dust sampler are input to the calculator, and the radiation concentration at each point to be measured is calculated here. It is possible to continuously measure the radioactivity concentration contained in it without the need for sampling pipes, and there is no deposition in the sampling pipes.
Measurement accuracy is improved, sampling points can be easily changed (moved) or added, and even if the dust sampler at one location fails, the entire system can be disconnected and operated.

(Example) Hereinafter, the Example of this invention is described with reference to drawings. FIG. 1 is a diagram showing a schematic configuration of an embodiment of the present invention. This is an optical transmission in which the functions of a conventional dust monitor for concentration measurement and a continuous dust monitor are organically combined and sublimated with an optical transmission technique. It is a continuous dust monitor of the method. That is, the dust sampler SM for sampling the air around the installation location and collecting the dust from the dust collecting port IN on the dust collecting filter paper F is arranged at each measurement point. A filter body feed mechanism such as a filter paper feed mechanism FD capable of continuously feeding a filter body such as a filter paper to each dust sampler SM, and a suction pump P for sucking a fluid at a point to be measured such as air through the filter paper F. , A flowmeter FM for detecting the amount of air sucked into the suction pump P, a radiation detector DT for detecting the radiation dose of dust collected by the filter paper F, and detection of the radiation detector DT and the flowmeter FM. It is equipped with an optical interface OI for inputting signals and converting them into optical pulse signals, and for inputting / outputting control / calculation signals from the digital monitor DM, which is a control calculation unit described later, to the suction pump P and filter paper feed mechanism FD. ing. An optical transmission line C is connected to the optical interface OI of each dust sampler SM, and each optical transmission line C is digitally monitored via the optical interface OI.
Commonly connected to DM. This digital monitor DM
Is a device that can control the input / output signals for each dust sampler SM, calculate the radiation concentration based on the detection signals of the flowmeter FM and the radiation detector DT, and display the calculation result on a display device, etc. Is.

In the continuous dust monitor configured as described above, the dust sampler SM is arranged at each point to be measured, and the detection signals of the radiation detector and the flowmeter included in the dust sampler SM are sent to the optical interface OI, the optical transmission line C, Optical interface
It is input to the digital monitor DM via OI, and the radiation concentration at each measurement point is monitored here.

Table 1 shows the difference in structure between the continuous dust monitor according to the present invention and the conventional continuous dust monitor and the dust monitor for concentration measurement.

Since the structure is different as shown in Table 1, the following effects can be obtained.

(1) Input the detection values of the radiation detector DT and the flow meter FM of the dust sampler SM arranged at each point to be measured to the digital monitor DM common to each dust sampler DM,
Since the radiation concentration is calculated here and the result of this calculation is continuously displayed, it is possible to continuously measure the radiation concentration continuously from dust contained in the air at the point to be measured.

(2) Since the sampling pipe L and the valve changer V for sampling are not required unlike the conventional continuous dust monitor, there is no deposition in the sampling pipe, the measurement accuracy is improved, and the sampling pipe is improved. Since it is not necessary, the construction cost can be reduced, and the sampling points can be changed (moved) and expanded easily.

(3) The dust sampler SM is installed corresponding to the point to be measured, and the detection outputs of these are input to the common dust sampler SM, so one dust sampler SM fails. However, the entire system will not stop functioning by disconnecting only the faulty dust sampler SM.

(4) The filter paper feed mechanism FD, the suction pump P, etc. can be controlled automatically or manually according to the calculation result by the digital monitor DM.

2 to 4 are diagrams showing a connection state of an optical transmission line as an information communication system between the dust sampler SM and the digital monitor DM of the present invention. 2 shows a bus system, FIG. 3 shows a network system, and FIG. 4 shows a star coupler system. Table 2 shows a comparison between these merits and demerits. Actually, these methods are selected with reference to Table 2.

In the embodiment described above, each sampler SM and digital monitor DM
Although the optical transmission line C is used as the signal transmission line for the above, the transmission line is not limited to this, and multiplex transmission may be performed using a metal cable such as a coaxial or twisted pair two-core cable. In this case, the optical interfaces OI provided on both ends of the optical transmission line C are unnecessary.

[Advantages of the Invention] According to the present invention described above, the radioactivity concentration contained in dust can be continuously measured without interruption, no sampling pipe is required, no deposition occurs in the sampling pipe, and the measurement accuracy is high. To provide a continuous dust monitor that can be operated separately by changing (moving) sampling points and increasing the number of sampling points easily, even if the dust sampler at one location fails, without disconnecting the entire system. You can

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing an embodiment of a continuous dust monitor according to the present invention, and FIGS. 2 to 4 are diagrams for explaining an information communication system used in the present invention. FIG. 5, FIG. 5 and FIG. 6 are schematic diagrams showing different conventional dust monitors. SM: Sampler, IN: Dust collection port, FD: Filter paper feed mechanism,
F: filter paper, FM: flow meter, P: suction pump, OI ...
Optical interface, DT ... Radiation detector, C ... Optical transmission line, DM ... Digital monitor.

Claims (1)

[Claims] 1. A measurement fluid, which is arranged corresponding to a point to be measured, can be continuously introduced into a flow channel by a fluid suction means, and the fluid can be continuously introduced into the flow channel when the fluid is introduced into the flow channel. A plurality of samplers each having a flow meter for filtering the dust contained in the fluid with a filter provided in a mechanism capable of feeding and detecting the flow rate of the fluid introduced into the flow path, and each filtration for each sampler A plurality of radiation detectors respectively detecting the radiation dose of dust filtered by the body, a radiation detector for each sampler and a computing unit for computing the radiation concentration by inputting detection signals from the flow meter, A continuous dust monitor equipped with an indicator that displays the calculation results of the instrument.