JPH09257936A - Radioactive gas monitor - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To provide a radioactive gas monitor capable of accurately specifying a leaking portion of radioactive gas and having a small burden on an operator. A suction unit includes a suction nozzle for sucking gas (air) and an indicator for displaying a measurement result.
And 4. The suction nozzle 32 has a flexible hose 4
It is connected to the detection tank 15 of the measurement unit 10 via 0. When the pump 12 of the measurement unit 10 is operated, the gas around the suction port at the tip of the suction nozzle 32 is sucked and guided to the detection tank 15 via the hose 40. The measurement result of the measurement unit 10 is given to the indicator 34 of the suction unit 30 via the cable 42. The operator carries the small and lightweight portable suction unit 30 and searches the leaking location of the radioactive gas while looking at the display of the indicator 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radioactive gas monitor for detecting a radioactive gas, and more particularly to a radioactive gas monitor used for identifying a leaking point of the radioactive gas.

[0002]

2. Description of the Related Art In a nuclear power plant or a facility for handling radioactive isotopes, it is necessary to constantly monitor whether or not radioactive gas is leaked or generated from pipes or devices in order to prevent workers from being exposed to radiation.

Conventionally, in order to monitor such radioactive gas leakage, a part of the exhaust gas from the exhaust duct of each room or the sampling gas from the sampling pipe is led to a stationary gas monitor to measure the concentration of the radioactive gas. Was measured. However, with this method, it is possible to detect the presence or absence of gas leakage or the like on a room-by-room basis, but it is impossible to specify a specific leakage location in the room.

Therefore, conventionally, for example, a small dust monitor is used to identify the leaked portion. in this way,
A small dust monitor was brought into the room, and dust was sampled and measured at each location to identify the leak location. This method indirectly detects a radioactive gas by detecting a particulate radioactive substance generated by the decay of the radioactive gas (a gaseous radioisotope). This method was effective for identifying the leak location of the source correlated with the particulate matter, but was not suitable for the source not correlated with the particulate matter.

Further, this method cannot cope with an instantaneous change because it is an integrated measurement.

[0006] Another method for identifying the leak location of the radioactive gas is to bring a small gas monitor into the room and perform measurement at each location.

[0007]

However, in the dust monitor, for example, for sampling dust, 15
Since it takes a considerable amount of time for a series of measurement work, such as about 20 minutes for radiation measurement and about 20 minutes for radiation measurement, it takes a very long time to perform measurement at each location in the room and identify the gas leakage location. was there.

Further, the dust monitor and the gas monitor described above are required to be equipped with a pump and a detection mechanism although they are small in size, so that the size and weight of the device are apt to be large and large, lacking maneuverability, and being difficult for a measuring operator. There was a problem that the burden was heavy.

The present invention has been made in order to solve such a problem, and it is an object of the present invention to provide a radioactive gas monitor capable of accurately specifying a leaking point of radioactive gas and having a small burden on an operator. To aim.

[0010]

In order to achieve the above-mentioned object, a radioactive gas monitor according to the present invention comprises a detector for detecting radiation and a pump for introducing an external gas into the detector. It is characterized by having a unit, a portable suction unit including a suction nozzle having a small suction port for searching a gas leakage source, and a hose for guiding gas from the suction nozzle to the detection unit.

In this structure, the operator holds the portable suction unit by hand and brings the small suction port of the suction nozzle close to a desired position to suck the ambient air. The air sucked from the small suction port is introduced into the detection unit of the measurement unit via the hose, and the radiation is detected and measured. By detecting the radiation at each location in this way, the leaking location of the radioactive gas can be specified.

According to this structure, the measuring unit is provided with large-sized and heavy components such as the detection unit and the pump, and the portable suction unit held by the operator has a small and lightweight structure. The burden on the operator can be significantly reduced, and the measurement can be performed even in a place where the gas monitor could not be brought close due to the limitation of the weight and size in the past. Further, according to the present invention, since the air is sucked from the small suction port of the suction nozzle, it is possible to precisely specify the leaking location of the radioactive gas.

Further, the present invention is characterized in that the portable suction unit is provided with a result output section for showing a measurement result obtained by the measuring unit.

With this configuration, the measurement result obtained by the measurement unit is output to the result output section of the portable suction unit. This output may be, for example, a visual display of the measured value or an audio output such as an alarm. The worker can identify the leakage location of the radioactive gas by referring to the result output from the result output unit. According to this configuration, even when performing suction at a location away from the measurement unit, the operator can know the measurement result by the result output unit of the portable suction unit, so that a single operator can perform a wide range search. It becomes possible to do.

Further, the present invention is characterized in that at least a part of the suction nozzle is formed of a flexible material.

In this structure, since a part of the suction nozzle has a flexible structure, the suction port of the suction nozzle can be brought close to a deep place such as a back side portion of the pipe.

Further, the present invention is characterized in that a sensor for detecting a physical characteristic of gas is provided in the vicinity of the suction port at the tip of the suction nozzle.

In this structure, a sensor for detecting the physical characteristics of the gas (for example, temperature, humidity, etc.) is provided in the vicinity of the suction port at the tip of the suction nozzle, so that the characteristics of the gas including radioactivity can be comprehensively determined. be able to. Also, if the suction nozzle is equipped with a sensor such as a temperature sensor that can obtain the detection result in a shorter time than the measurement by the gas monitor, the sensor is used to perform a rough search in advance, and the result of this search is leaked. It is also possible to adopt a method in which radiation is measured only where it is determined that there is a possibility that the leakage is determined. This method is effective, for example, when it is known that the temperature of the radioactive gas to be detected is higher than the room temperature of the measurement target chamber.

It is also possible to arrange the portable suction unit in the measurement target chamber, pass the hose through a through hole provided in a partition wall that divides the inside and outside of the measurement target chamber, and dispose the measurement unit outside the measurement target chamber. Characterize.

According to this structure, since the measurement unit is arranged outside the measurement target room where the background radiation is small, the radiation detection limit can be improved.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a radioactive gas monitor according to the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram showing the configuration of an embodiment of a radioactive gas monitor according to the present invention. As shown in FIG. 1, the radioactive gas monitor according to the present embodiment includes a measurement unit 10 including a pump 12 and a detection unit 14 for measuring radiation.
A portable suction unit 30 held by the worker during measurement work,
And a flexible hose 40 and a cable 42 that connect the measurement unit 10 and the suction unit 30.

The suction unit 30 includes a suction nozzle 32 for sucking gas (air) and an indicator 34 for displaying a measurement result.
And The appearance of the suction unit 30 is shown in FIG. As shown in FIG. 2, the suction unit 30 includes a suction nozzle 32 and a grip portion 36 held by an operator. The suction nozzle 32 has, for example, a length of about 1 m, and the suction port 32a at its tip has a relatively small diameter (for example, a diameter of 6 mm) so that the suction portion can be accurately specified. Further, the suction nozzle 32 is connected to the hose 40 in the grip portion 36. An indicator 34 is provided on the rear end surface of the grip portion 36.
The measurement unit 1 is provided with a cable 42 (not shown in FIG. 2) for data transmission arranged along the hose 40.
0 is connected to the measuring unit 18. The indicator 34
May be provided at a position other than the rear end surface of the grip portion 36, but is preferably provided at a position near the rear end of the grip portion 36 that is easily seen by an operator. The shape / structure of the suction unit 30 shown in FIG. 2 is merely an example, and other shapes / structures can be used.

Returning to FIG. 1 again, the suction nozzle 32 is connected to the detection tank 15 of the measuring unit 10 via a hose 40. The hose 40 has a certain length (for example, about 20 m) so that the hose 40 can be searched throughout the room. When the pump 12 of the measurement unit 10 is operated, the gas around the suction port 32a at the tip of the suction nozzle 32 is sucked and guided to the detection tank 15 via the hose 40.

In the measurement unit 10, the detector 16 detects the radiation emitted from the gas introduced into the detection tank 15 of the detection unit 14. As the detector 16, any type of detector may be used depending on the detection target. As an example, a detector using a plastic scintillator can be used. In the present embodiment, the detection unit 14 is, for example, a gas flow type.

The measuring unit 18 uses the detection signal of the detector 16 to detect the amount of radiation of the gas in the detection tank 15 (for example, cpm).
Value). This measurement result is output to the indicator 20 and also to the indicator 34 of the suction unit 30 via the cable 42. Each of the indicators 20 and 34 displays this measurement result. The worker uses the suction unit 30.
While looking at the indicator 34, each location in the room is searched to identify the leakage location.

In this embodiment, the operator holds the suction unit 30 and brings the suction port 32a at the tip of the suction nozzle 32 into contact with a portion where gas may leak, and sucks the gas around it. For example, if the volume of the detection tank 15 is set to about 1 liter and the suction nozzle 32, the hose 40, and the flow rate of about 3 times the volume of the detection tank 15, the gas in the detection tank 15 can be replaced in about 1 minute. it can. Therefore, with this device, it is possible to quickly determine the possibility of gas leakage in about 1 minute per location.

In the present embodiment, the pump 12 and the detector 14
Since the measuring unit 10 including a relatively large and heavy member such as the above is installed on the floor and the operator carries the small and lightweight portable suction unit 30 to search for a gas leakage location, The burden on the operator during work is greatly reduced. Further, according to the present embodiment,
Mobility is improved by making it easy to measure high positions such as piping near the ceiling.

Further, in this embodiment, the suction unit 30
An indicator 34 for visually displaying the measurement result was provided in the, but instead of the indicator 34, the measurement result is voiced, such as an alarm that generates a louder sound as the radioactivity concentration increases. You may provide the apparatus shown by. Note that, for example, if a work procedure in which two workers are paired and one person monitors the indicator 20 of the measurement unit 10 and reports the result to the operator of the suction unit 30 is possible, The indicator 34 of the suction unit 30 is not always necessary.

Next, another structure of the suction nozzle 32 of the suction unit 30 will be described with reference to FIG. In the configuration of FIG. 3, part of the suction nozzle 32 is made of a flexible material. This portion is called a flexible portion 32b. The suction nozzle 32 has a structure in which the flexible portion 32b is bendable. Therefore, according to this configuration,
Suction nozzle 3 even in recessed parts such as the back side of piping
The two tips can be brought closer together. Further, the suction nozzle 32 has a tapered shape from a portion attached to the grip portion 36 toward the suction port 32a at the tip.

In the structure shown in FIG. 3, part of the suction nozzle 32 has a flexible structure, but the suction nozzle 32 may have a flexible structure as a whole. Further, the suction nozzle 32 may be detachably attached to the grip portion 36, and a plurality of kinds of suction nozzles 32 may be appropriately selected and used. In addition, a mesh (aperture ratio of 60% or more) may be attached to the inside of the grip portion 36 so that the hose 40 does not get bogged when a large amount of dust is sucked.

FIG. 4 shows an example in which a temperature sensor 38 is provided at the tip of the suction nozzle 32. The gas monitor requires a certain amount of time until the gas inside the detection tank is replaced, so a corresponding time is required for measurement (about 1 minute in the above example).
Cost. Compared with this, the temperature sensor has extremely quick response. Therefore, when the temperature of the radioactive gas to be detected has a temperature difference from the atmospheric gas (eg, air) in the vicinity of the leak point, the temperature sensor 38 is provided near the suction port 32a at the tip of the suction nozzle 32 as shown in FIG. As a result, it is possible to identify a location where gas leakage is likely to occur in almost real time. That is, in this configuration, after the temperature sensor 38 roughly identifies a location where gas leakage is likely to occur, the gas at that location is actually sucked to measure the radioactivity, thereby determining the presence or absence of leakage of the radioactive gas. To confirm. By such a procedure, it is possible to quickly identify the gas leakage point.

In this structure, in addition to the indicator for displaying the radiation measurement result, the temperature sensor 3 is provided on the grip 36.
An indicator (not shown) that displays the detection result of 8 is provided. The output signal of the temperature sensor 38 is supplied to the indicator through a signal line (not shown). The output signal of the temperature sensor 38 may also be supplied to the measuring unit 10.

A sensor other than a temperature sensor such as a humidity sensor may be provided at the tip of the suction nozzle 32. If the sensor provided in the suction nozzle 32 has a quicker response than that of the gas monitor, it can be used for a rough search for a gas leak location similar to the temperature sensor 38 described above. Further, the data from these sensors can be used together with the measurement result of the radiation by the measurement unit 10 for comprehensive determination of the type of leaked gas.

Next, a preferred example of the device arrangement in this embodiment will be described. In the present embodiment, it is of course possible to bring the measurement unit 10 into the room to be measured and perform the measurement, but if the influence of background radiation is taken into consideration, only the suction unit 30 is brought into the room and the measurement unit 10 is placed outdoors. It is more preferable to adopt an arrangement configuration in which That is, the room to be measured by the radioactive gas monitor of the present embodiment (measurement target room) is usually a room in which leakage of radioactive gas is detected by room-by-room measurement. Therefore, when the measuring unit 10 is brought into the room, the radiation from the radioactive gas diffused in the room becomes the background, and the detection limit is deteriorated to some extent. In addition, the room where the pipes and valves are installed generally has a high background due to the radiation from the radioactive gas in the pipes. On the other hand, the measurement unit 10 is installed outside the measurement target chamber, and the suction unit 30
If the configuration is such that only one is brought into the room, the background becomes low and the detection limit can be improved. In this case, the hose 40 needs to be routed from the indoor suction unit 30 to the outdoor measurement unit 10. To do this, for example, on the partition that separates the room from the outside,
An insertion hole provided with a valve may be provided. According to this configuration, it is possible to prevent the air in the room from leaking to the outside by closing the valve at the normal time, while inserting the suction nozzle 32 and the measurement unit 10 from the inside and the outside of the room, respectively, at the time of measurement. By connecting to the hole and opening the valve, the gas sucked from the suction nozzle 32 can be introduced into the measurement unit 10.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a radioactive gas monitor according to the present invention.

FIG. 2 is a perspective view showing an example of a configuration of a suction unit.

FIG. 3 is a perspective view showing an example of a configuration of a suction nozzle.

FIG. 4 is a perspective view showing a suction nozzle provided with a temperature sensor.

[Explanation of symbols]

10 measuring unit, 12 pump, 14 detector, 1
5 detection tanks, 16 detectors, 18 measuring parts, 20 indicators, 30 suction units, 32 suction nozzles, 34 indicators, 36 grips, 40 hoses, 42 cables.

Claims (5)

[Claims] 1. A measuring unit having a detection unit for detecting radiation, a pump for introducing an external gas into the detection unit, and a suction nozzle having a small suction port for searching a gas leakage source. A radioactive gas monitor, comprising: a portable suction unit; and a hose that guides gas from the suction nozzle to the detection unit. 2. The radioactive gas monitor according to claim 1, wherein the portable suction unit is provided with a result output section that shows a measurement result obtained by the measurement unit. 3. The radioactive gas monitor according to claim 1, wherein at least a part of the suction nozzle is made of a flexible material. 4. The radioactive gas monitor according to claim 1, wherein a sensor for detecting a physical characteristic of gas is provided in the vicinity of the suction port at the tip of the suction nozzle. Gas monitor. 5. The radioactive gas monitor according to any one of claims 1 to 4, wherein the portable suction unit is arranged in a measurement target chamber, and the hose is provided on a partition wall that divides the inside and the outside of the measurement target chamber. A radioactive gas monitor characterized in that the measurement unit is arranged outside the chamber to be measured through a conduction hole.