JPH0424586A - Simple-type dust sampler - Google Patents

Abstract

PURPOSE:To enable sharp reduction of the weight by rotating a rotary disk at a prescribed speed, by driving a prescribed flow rate of sample air against a dust sticking surface on the rotary disk by a blower and by measuring dust caught and collected on the dust sticking surface, by a radiation detector. CONSTITUTION:A flat rotary disk 1 is fitted to a shaft of a motor 3. An adhesive sheet 2 is stuck on the surface of this disk 1 being opposite to the motor 3, so as to prepare a dust sticking surface. A blower 5 is disposed so that a blowoff port thereof is opposed to the dust sticking surface and that the axial line of the blowoff port is made parallel to the shaft of the motor 3. On the opposite side of the motor 3 to the blower 5, a radiation detector 4 is disposed so that a detecting surface thereof is opposed in proximity to the dust sticking surface. The disk 1 is rotated at a prescribed speed, a prescribed flow rate of sample air is driven against the dust sticking surface by the blower 5 and the dust caught and collected on this surface is measured by the detector 4. When the drive of the sample air is continued, an output of the radiation detector increases with time and saturated after a certain time. The time till it is saturated is in reverse proportion to the concentration of the dust in the air, while the strength of radioactivity measured at the point of saturation is in proportion to the strength of the radioactivity in unit dust. When the time of the saturation and the output of the detector at the time point of the saturation are known, accordingly, the radioactivity in the air can be calculated with ease.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention collects dust floating in the atmosphere inside the building of a nuclear facility, and detects the radioactivity of the dust using a radiation detector. Concerning a dust sampler that measures and determines radioactivity in the atmosphere.

(Conventional technology) Among the buildings of nuclear power facilities, there are rooms where dust sampling points are not installed to measure the radioactivity of dust floating in the indoor atmosphere, and there are sampling points installed but continuous sampling is not required. A simple dust sampler that is easy to carry and move is used to measure dust radioactivity when and where necessary for the purpose of environmental monitoring at work sites, such as in rooms where dust is not being used. be.

A conventional example of this simple dust sampler is shown in FIG. As shown in the figure, a filter paper feeding mechanism (
I3) is arranged, and the filter paper (
12) is equipped with a radiation detector (11) that measures the radioactivity of the collected dust, and a suction pump (19). The suction section (19) is equipped with a flow meter (16), a pressure gauge (17), a filter (18), and a valve.
B).

Although it is said to be movable, the total weight of the dust collecting section (A) and the suction section (B) is about 80 kg, requiring a great deal of effort to carry it around.

(Problems to be Solved by the Invention) A portable and simple dust sampler is required to be small and lightweight, but there is a limit to the weight reduction with the conventional configuration shown in Fig. 4. A sampler method was required. Therefore, the object of the present invention is to realize a simple dust sampler that can be significantly reduced in weight in place of the method in which dust is collected by suction with a pump and collected on a filter paper, and that is also the purpose of the present invention. .

[Structure of the invention]

(Means for Solving the vA Problem) The simple dust sampler of the present invention includes a rotating disk attached to a motor shaft and rotated at a predetermined speed, and a dust sampler provided on a surface of the rotating disk facing the motor. an adhesion surface,
A blower is arranged with an air outlet facing the dust adhesion surface of the rotating disk and with the axis of the air outlet parallel to the motor shaft, and a blower is placed with a detection surface close to and facing the dust adhering surface of the rotating disk. a radiation detector and the motor.

One has a bracket that holds a blower and a radiation detector and organizes them into a portable device, and the other has a configuration in which the rotating disk is replaced with an impeller, a dust adhesion surface is formed on the blade, and the blower is removed. There are things.

(Function) In the simple JIS 1 to sampler of the present invention, the rotating disk is rotated at a predetermined speed, and a blower blows a constant flow rate of sample air onto the dust adhering surface on the rotating disk, and the sample air is captured on the dust adhering surface. The collected dust is measured with a radiation detector.

In the case of a simple dust sampler with an impeller, the impeller is rotated to create a flow of air from the front to the rear of the impeller, and the dust is collected on the dust adhesion surface on the back of the impeller, and the dust is detected for radiation. Measure with a device.

In both cases, the output of the radiation detector increases with time and saturates after a certain amount of time. Radioactivity in the atmosphere (μci/m3) is determined from the time until saturation and the detector output at the time of saturation.
can be found.

(Example) Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

FIGS. 1(a) and 1(b) show a simple dust sampler according to an embodiment of the present invention. As shown, a flat rotating disk (]) is attached to the shaft of the motor (3). For installation, a thread is cut in the shaft of the motor (3) in the opposite direction of rotation, and the rotating disk (1) is tightened with a nut, making installation and removal easy.

The surface of the rotating disk (1) facing the motor (3) is made into a dust-attached surface by pasting an adhesive sheet (2).

Further, a blower (5) is disposed with an outlet facing the dust adhering surface of the rotating disk (1) and with the axis of the outlet parallel to the shaft of the motor (3).

Further, on the opposite side of the motor (3) from the blower (5), a radiation detector (4) is arranged with its detection surface closely facing the dust adhesion surface of the rotating disk (1). And the motor (
3), the blower (5) and the radiation detector (4) are held together by a bracket (6) and assembled into a portable device. Note that (7) is a handle and (8) is a guard.

In the simple dust sampler of the embodiment of the present invention constructed as described above, the rotating disk ( ) is rotated at a predetermined speed, and dust is adhered by the adhesive sheet (2) on the rotating disk (1). A constant flow rate of sample air is blown onto the surface by a blower (5), and the dust collected on the dust-attached surface is measured by a radiation detector (4).

When the sample air is continued to be blown and the measurement by the radiation detector is continued, the output of the radiation detector increases with time and becomes saturated after a certain period of time. The time it takes to reach saturation is shorter as the amount of dust in the air increases, and longer as the amount of dust is lower. The relationship between the dust concentration in the air and the constant radioactivity intensity of radiation detector (4) is shown in Figures 3 (a), (b), and (c).

In the figure, (A) represents the air volume hitting the rotating disk (1), (B) represents the unit dust, and (C) represents the unit radioactivity. Moreover, (Y/X) indicates the ratio of the measured radioactivity intensity at the saturation point and the sampling time. Figure 3(b), Figure 3(
c) shows the case where the dust concentration in the air is two times and three times the concentration in FIG. 3(a), respectively, and b. As is clear from the figure, the time to reach the saturation point is inversely proportional to the dust concentration in the air. Also, the measured radioactivity intensity (detector output) at the saturation point.

It is proportional to the radioactivity intensity in unit dust.

That is, saturation time = K・(dust concentration in the air) ゛------ (1) Measured radioactivity intensity = 2 (radioactivity intensity in unit dust)... (2) Here Kx , Kz is a proportionality constant. Therefore, =K (Radioactivity in the atmosphere) In other words, the radioactivity in the atmosphere (μci/m3) is proportional to .

The above value of K can be obtained by calibrating the measurement system, so if the saturation time and the detector output at the time of saturation are known, the radioactivity in the atmosphere can be easily calculated.

Now, if the time to reach the saturation point is long.

By analyzing initial short-term data, the saturation point can also be predicted. Using this method, the concentration of dust radioactivity in the environmental space can be measured in a short period of time.

The simple dust sampler shown in Figure 1 consists of a rotating disk (1)
Since it is flat, the radiation detector (4) can be brought close to the radiation detector (4) for measurement, and highly sensitive measurement is possible. In addition, the sampling air containing dust is detected by the radiation detector (4).
Therefore, the problem of high background due to contamination of the detection surface of the radiation detector (4) is unlikely to occur.

Since the configuration is completely different from the conventional system shown in FIG. 4, the weight is approximately 1710 mm compared to the conventional system, making it effective as a portable dust sampler. Furthermore, it is easy to handle because it is only necessary to replace the adhesive sheet (2) instead of replacing the filter paper.

Next, another embodiment of the present invention will be described with reference to FIGS. 2(a) and 2(b). The simple dust sampler of this example is
An impeller (9) is used instead of the rotating disk (1) in the simple dust sampler shown in Fig. 1, and the impeller (9) has a configuration in which the blower (5) is removed. An adhesive sheet (2) is pasted on the surface to form a dust adhesion surface.

In the simple dust sampler of this example, the motor (
3) rotates the impeller (9) at a predetermined speed, causing air to flow from the front to the rear of the impeller (9) as shown by the arrow, thereby causing dust to adhere to the surface on the back of the impeller (9). The dust is collected and the dust is measured by the radiation detector (4).6 The subsequent data processing and effects are the same as in the embodiment shown in FIG.

The simple dust sampler shown in Fig. 2 has the advantage of being lightweight since it does not require a blower, but since the impeller (9) is twisted, the dust on the detection surface of the radiation detector (4) and the back of the blade is The detection distance from the adhesion surface increases, and the detection sensitivity decreases accordingly. Furthermore, since the air flow hits the radiation detector (4), there is a risk that the detection surface of the detector will be contaminated and the back ground will become high.

〔Effect of the invention〕

As detailed above, according to the present invention, a rotating disk or an impeller is rotated at a predetermined speed by a motor, and a constant flow rate of sample air is blown onto the dust adhesion surface by a blower provided on the rotating disk, or by using the impeller. A flow of sample air is generated to collect dust on each dust adhesion surface, and the collected dust is measured with a radiation detector until it reaches the measured radioactivity intensity when the detector output is saturated. By creating a simple dust sampler that determines radioactivity in the atmosphere based on the amount of time, the weight can be reduced to about 1/10 compared to the conventional method of suctioning with a pump and collecting dust on filter paper. , portability is greatly improved.

Furthermore, it is easy to handle because it is only necessary to replace the adhesive sheet forming the dust adhesion surface instead of replacing the filter paper. Furthermore, since the structure is simple, it has the advantage that it can be manufactured at low cost.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are a schematic side view and a front view of a rotating disk of a simple dust sampler according to an embodiment of the present invention, respectively, and FIGS. 2(a) and (b) are respectively a schematic side view and a front view of a simple dust sampler according to an embodiment of the present invention. A schematic side view of the simple dust sampler according to the embodiment and a front view of its impeller, FIG. 3(a); (b), (
C) is a diagram showing the relationship between the dust concentration in the air and the measured radiation intensity, and FIG. 4 is a schematic diagram showing a conventional portable simple dust sampler. DESCRIPTION OF SYMBOLS 1... Rotating disc, 2... Adhesive sheet, 3... Motor, 4... Radiation detector, 5... Blower, 6...
Bracket, 9...impeller. Agent Patent Attorney Norio Ogo (a) (b) Figure ■ (a) (b) Figure Figure Figure Figure

Claims (2)

[Claims] (1) A motor, a rotating disk attached to the shaft of the motor and rotated at a predetermined speed, a dust adhering surface provided on the surface of the rotating disk facing the motor, and dust adhering to the rotating disk. a blower disposed with an outlet facing the surface and with its axis parallel to the motor shaft; a radiation detector disposed with a detection surface closely facing the dust adhering surface of the rotating disk; and the motor; A simple dust sampler equipped with a blower and a bracket that holds a radiation detector and organizes it into a portable device. (2) A motor, an impeller attached to the shaft of this motor and rotated at a predetermined speed, a dust adhesion surface provided on the surface of this impeller facing the motor, and a dust adhesion surface of this impeller detected. A simple dust sampler comprising a radiation detector whose surfaces are placed close to each other and a bracket that holds the motor and the radiation detector and organizes them together as a portable device.