JPH0792271A - Radiation measuring method - Google Patents

Abstract

PURPOSE:To precisely measure the radiation concentration of dust particles by a method wherein the radiation of captured and collected dust particles is counted and the counted value of the radiation of the atmospheric gas is subtracted from its counted value. CONSTITUTION:A control device 10 closes a boundary part 3a, the circumference of a radiation detector 13 in a dust collection part 3 is filled with a sampling gas, and a gas suction operation is suspended (a dust-collection selection valve 5 is closed and a bypass selection valve 8 is opened) so as to prevent dust particles from being accumulated on the filter paper 2. The detector 13 counts the radiation of the gas atmosphere, and its counting rate is sent to a data processing device 12. The device 12 computes a background counting rate BG. The device 10 opens and closes the valves 5, 9, and dust particles in the gas are accumulated on the filter paper 2. The detector 13 sends a dust counting rate to the device 12 at every prescribed time. The device 12 subtracts the BG from the dust counting rate, it finds a net dust counting rate, it integrates the dust collecting time, and it finds the next counted number. The number is divided by the volume of the gas, and the radiation concentration of dust particles in the air of a measuring place is measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation measuring method for measuring the dust radiation concentration in the air of a nuclear facility,
In particular, the present invention relates to a radiation measuring method capable of improving the measurement accuracy by accurately estimating the background count value at the start of collection.

[0002]

2. Description of the Related Art Generally, in measuring the dust radiation concentration in the air of a nuclear facility, dust in the air is collected (dust collection) by filter paper while sucking the air at the measurement location in the facility.
A dust radiation monitor is widely used to measure the dust radiation concentration in the air by measuring the dust radiation.

FIG. 8 is a time chart showing the operation of this type of dust radiation monitor. In this dust radiation monitor, a sampling pipe for sucking air from a measurement place in the facility is connected to a suction pump from a filter paper and its drive unit via a dust collecting pipe and a dust collecting selection valve. The sampling pipe is connected to the suction pump via the bypass pipe and the bypass selection valve.

Now, as shown in FIG. 8A, when the bypass selection valve is opened and the dust collection selection valve is closed,
The air sucked from the sampling pipe is discharged to a duct (not shown) via the bypass pipe and the suction pump.

At this time, the drive unit moves the filter paper and introduces a new filter paper surface into the sampling pipe (time t1).
Here, the radiation detector arranged above the filter paper is shown in FIG.
As shown in (b), the radiation on the filter paper is counted and the count rate is sent to the data processing device. At this time, no radioactivity has accumulated on the filter paper (state a), and the count rate shows the lowest value. Based on the count rate, the data processing device is shown in FIG.
As shown in (c), the background count rate BG is measured (period Tb).

Then, the bypass selection valve is closed,
When the dust collection selection valve is opened (time t2), the air sucked into the sampling pipe passes through the filter paper, is sucked into the suction pump, and is discharged into the duct. In addition, dust in the air, when the sucked air passes through the filter paper,
It is collected on the filter paper (state c).

On the other hand, the radiation detector counts the radiation of dust collected on the filter paper and sends the counting result to the data processor. The data processing device measures the dust radiation concentration in the air as shown in the following equation (1) based on the counting result and the background counting rate BG described above (within the period Tc).

[0008]

[Equation 1]

However, NET count; (detector output count rate-
Background count rate) × time or (detector output count rate × time−background count rate × time) Here, the output count rate of the radiation detector is as shown in FIG. Rises sharply at. This is because there are two types of radiation sources contained in the air at the measurement location: gaseous ones and particulate ones. This is because it is counted. The air at the measurement location contains more radioactivity than the air at the location where the dust radiation monitor is installed.

After a certain amount of dust collection time has passed, particulate matter (dust) is accumulated on the filter paper, and the dust radiation concentration is measured in proportion to the accumulated amount. This allows
The measured value of dust radiation concentration is higher than the actual value in the initial stage of dust collection, but approaches the actual value as the dust collection time elapses.

That is, at the initial stage of dust collection, the NET count in the numerator of equation (1) rises rapidly and the dust collection time in the denominator of equation (1) takes a small value, resulting in equation (1). The dust radiation concentration obtained by is an unnecessarily high value. After the measurement is completed, the drive unit moves the filter paper to introduce a new filter paper surface into the sampling pipe (time Tc) in the same manner as described above, thereby starting the next measurement.

[0012]

However, in the radiation measuring method as described above, there is a problem that the dust radiation concentration is rapidly increased and measured due to the increase in the output count rate of the detector at the initial stage of dust collection. is there.

This increase is large in proportion to the radiation concentration difference between the installation location of the dust radiation monitor and the measurement location. This may exceed the dust radiation warning level. Also, when the alarm level is exceeded, not only is the entry into the measurement location restricted, but even if the entry is possible, radioactive dust should not be inhaled from the respiratory organs.
It is necessary to wear a mask with a filter to enter the area.

Further, if the mask is worn, the workability may be poor and the work may not be completed during the scheduled period.
The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a radiation measurement method capable of correcting a measurement error due to a count increase at the start of dust collection and improving the accuracy of measurement of dust radiation concentration. And

[0015]

The invention according to claim 1 is characterized in that a gas containing dust is sucked through a filter paper and the radiation emitted from the dust collected on the filter paper is counted. In a radiation measuring method for obtaining a dust radiation concentration in a gas, when sucking the gas, while filling the periphery of the filter paper with the atmosphere of the gas, interrupting the suction to count the radiation of the atmospheric gas, When the counting of the radiation of the atmospheric gas is completed, the suction is restarted to collect the dust on the filter paper, the radiation of the collected dust is counted, and the atmospheric gas is counted from the counted value of the radiation of the dust. Is a radiation measurement method for calculating the dust radiation concentration based on the subtraction result.

Further, the invention according to claim 2 sucks a gas containing dust through a filter paper, counts the radiation emitted from the dust collected on the filter paper, and based on this dust radiation count value. In the radiation measurement method for determining the dust radiation concentration in the gas, when determining the dust radiation concentration in the gas, the dust radiation count value counted after a predetermined time has elapsed from the start of the collection. A radiation measuring method for calculating the dust radiation concentration based on the above.

Further, in the invention corresponding to claim 3, the gas containing dust is sucked through the filter paper, the radiation emitted from the dust collected on the filter paper is counted, and the dust radiation count value is used. In the radiation measurement method for determining the dust radiation concentration in the gas, when determining the dust radiation concentration in the gas, the dust radiation count value counted after exceeding a predetermined count value from the start of the collection A radiation measuring method for calculating the dust radiation concentration based on the above.

In the invention according to claim 4, the background radiation is counted to obtain the background count value, the gas containing dust is sucked through the filter paper, and the dust collected from the filter paper is collected. Emitted radiation is counted, by subtracting the background count value from the dust radiation count value, in a radiation measurement method for determining the dust radiation concentration in the gas, as the process for determining the background count value, The radiation measuring method includes a calculation process of counting background radiation to obtain an original count value and adding a predetermined added value to the original count value.

Further, in the invention corresponding to claim 5, the gas containing dust is sucked through the filter paper, the radiation emitted from the dust collected on the filter paper is counted, and the dust radiation count value is used. In the radiation measuring method for obtaining the dust radiation concentration in the gas, when the dust radiation concentration in the gas is obtained, the radiation amount of the dust accumulated on the filter paper from the start of the collecting is counted, and this counting is performed. The count value N is calculated by integrating the results at regular intervals
The count value N2 by 1 and the next integration is calculated, and the background count value BG is calculated by substituting the count values N1 and N2 for the first time and the next time into the following formula, and the background count value BG is calculated from the dust radiation count value. It is a radiation measuring method of subtracting and calculating the dust radiation concentration based on the subtraction result. BG = (3N1-N2) / 2

[0020]

Therefore, according to the invention corresponding to claim 1, by taking the above means, when the gas is sucked, the atmosphere around the filter paper is filled with the gas atmosphere and the suction is interrupted. When the radiation is counted and the radiation of the atmosphere gas is finished, suction is restarted to collect dust on the filter paper, and the radiation of the collected dust is counted,
The radiation gas count value is subtracted from the dust radiation count value, and the dust radiation concentration is calculated based on this subtraction result, so the measurement error due to the count increase at the start of dust collection is corrected, The accuracy of measurement of radiation concentration can be improved.

Further, in the invention corresponding to claim 2, when the dust radiation concentration in the gas is obtained, the dust radiation is counted based on the dust radiation count value counted after a predetermined time has elapsed from the start of the collection. Since the concentration is calculated, it is possible to correct the measurement error due to the count increase at the start of dust collection by the dead time of the predetermined time, and improve the accuracy of the measurement of the dust radiation concentration.

Further, in the invention corresponding to claim 3, when the dust radiation concentration in the gas is obtained, the dust radiation count value counted after a predetermined count value has been exceeded from the start of the collection is used as the dust radiation count value. Since the radiation concentration is calculated, the dead time until the predetermined count value is reached can correct the measurement error due to the count increase at the start of dust collection, and improve the accuracy of dust dust concentration measurement.

Further, the invention according to claim 4 is, as a process for obtaining a background count value, an operation for counting background radiation to obtain an original count value and adding a predetermined addition value to the original count value. Since it includes processing,
It is possible to correct the measurement error due to the count increase at the start of dust collection and improve the accuracy of measurement of the dust radiation concentration without causing a dead time at the start of collection.

Further, in the invention according to claim 5, when the dust radiation concentration in the gas is obtained, the radiation of dust accumulated on the filter paper is counted from the start of the collection, and the counting result is measured at regular intervals. The count value N1 obtained by the first integration and the count value N2 obtained by the next integration are calculated, and these first and next count values N1, N2 are calculated as "BG = (3N1-N2) /
The background count value BG is obtained by substituting it into the formula of 2 ", the background count value BG is subtracted from the dust radiation count value, and the dust radiation concentration is calculated based on the subtraction result. The measurement time can be shortened because the time for measuring the BG is not provided, and the measurement error due to the count increase at the start of dust collection is corrected to improve the accuracy of measurement of the dust radiation concentration. You can

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a dust radiation monitor according to the first embodiment of the present invention. In this dust radiation monitor, a sampling pipe 1 for introducing a sampling gas (air) is provided at a predetermined measurement place in the facility, and the sampling pipe 1 collects dust in the sampling gas by a filter paper 2 The dust collecting pipe 4 is connected to the suction pump 6 via the dust collecting selection valve 5.

The sampling pipe 1 is connected to the bypass pipe 7 before the dust collector 3, and the bypass pipe 7 is connected to the suction pump 6 via the bypass selection valve 8. The suction pump 6 sucks the sampling gas and discharges it to a duct (not shown).

Here, the dust collecting section 3 has an unwinding roller 2a on which the filter paper 2 is wound in advance and a filter paper 2 unwound from the unwinding roller 2a and traveling intermittently through the inside of the dust collecting section 3. And a take-up roller 2b for taking up the film are respectively arranged outside. The traveling direction of the filter paper 2 in the dust collecting portion 3 is orthogonal to the air suction direction.

The take-up roller 2b is driven by the filter paper drive unit 9, and the filter paper drive unit 9 is controlled by the controller 10. Further, the boundary portion 3 a between the filter paper 2 and the dust collecting portion 3 is closed or opened by the dust collecting portion driving portion 11, and the dust collecting portion driving portion 11 is controlled by the control device 10.

The control device 10 follows a predetermined control procedure.
The filter paper drive unit 9, the dust collection unit drive unit 11, the dust collection selection valve 5, and the bypass selection valve 8 are controlled, and the control timings thereof are sent to the data processing device 12.

Further, in the dust collecting section 3, a radiation detector 13 is arranged above the filter paper 2. The radiation detector 13 counts the radiation in the vicinity of the filter paper 2 and sends the count rate as a count result to the data processing device 12.

The data processor 12 measures the background count rate BG and the dust radiation concentration in the air at the measurement location based on the control timing received from the controller 10 and the count rate received from the radiation detector 13. And has a function of transmitting the measurement result to the display unit 14. The display unit 14 displays the measurement result received from the data processing device 12.

Next, a radiation measuring method using such a dust radiation monitor will be described with reference to the time chart of FIG. 2 and the schematic diagram of FIG. Now, it is assumed that the previous radiation measurement is finished and the radiation measurement is newly started this time.

As shown in FIG. 2 (e), the control device 10 closes the dust collecting selection valve 5 and opens the bypass selection valve 8 (time t3) so that the sampling gas flows through the bypass pipe 7. To

Subsequently, the control unit 10 controls the dust collecting section driving section 1
After controlling 1 to open the boundary 3a, the filter paper drive unit 9 is controlled to drive the take-up roller 2b to introduce a new filter paper 2 into the dust collecting unit 3.

Since the boundary portion 3a is opened in the dust collecting portion 3, as shown in FIGS. 3 (h) and 2 (f), the dust collecting portion 3 is formed.
Clean external air is introduced from the outside to the minimum state Na of the output count of the radiation detector 13 (state a).

Subsequently, the control device 10 closes the boundary portion 3a to stop the introduction of the external air, and thereafter opens the dust collecting selection valve 5 and closes the bypass selection valve 8. At time t4, as shown in FIG. 3I, the surroundings of the radiation detector 13 in the dust collecting unit 3 are filled with the atmosphere of the sampling gas to be replaced (state b). When the surroundings of the radiation detector 13 are replaced with the atmosphere of the sampling gas, the control device 10 does not accumulate the dust in the sampling gas on the filter paper 2, so the dust collecting selection valve 5 is closed and the bypass is performed. The selection valve is opened (time t5).

The radiation detector counts the radiation in the gas atmosphere and sends the count rate Nb to the data processor. Based on this count rate, the data processing device is shown in FIG.
As shown in (g), the background count rate BG is calculated and stored.

Next, the control device opens the dust collecting selection valve 5 and closes the bypass selection valve 8 (at time t).
6), as shown in FIG. 3 (j), the dust in the sampling gas is accumulated on the filter paper 2 (state c). Further, the radioactivity detector 13 sends out the dust count rate to the data processing device 12 every predetermined time corresponding to the accumulated amount of dust.

Thus, the data processing device 12 subtracts the background count rate BG having the above-mentioned Nb from the dust count rate received at every predetermined time to obtain the net dust count rate Nc, and collects the dust. By accumulating time, as shown in equation (1), the net count value NET
Find the count. Further, the data processing device 12 uses the NE
The T-count is divided by the volume of the sampling gas represented by the numerator of the equation (1) to measure the dust radiation concentration in the air at the measurement location, and the measurement result is sent to the display device 14.

The display device 14 is based on this measurement result.
The dust radiation concentration in the air at the measurement location is displayed. This completes the radiation measurement of this time.

Thereafter, similarly to the above, the radiation measurement for the next time and thereafter is executed. As described above, according to the first embodiment, when the sampling gas is sucked, the atmosphere around the filter paper 2 is filled with the gas atmosphere as shown in the state b, and the suction is performed so that dust is not accumulated on the filter paper 2. When the radiation of the atmosphere gas is interrupted and the radiation of the atmosphere gas is finished, suction is restarted to collect dust on the filter paper 2 and the radiation of the collected dust is counted. The atmospheric gas radiation count value was subtracted from the dust radiation count value, and the dust radiation concentration was calculated based on this subtraction result, so the measurement error due to the count increase at the start of dust collection was corrected. The accuracy of measurement of dust radiation concentration can be improved.

Next, a radiation measuring method according to the second embodiment of the present invention will be described with reference to the time chart of FIG. It should be noted that the method of the present embodiment is a measurement technique in which the replacement step by the sampling gas atmosphere for obtaining the background count rate BG is omitted as compared with the first embodiment, and specifically, the method has the same configuration as that of FIG. In the device, a predetermined idle time Td is provided from the time when the external air is introduced to the time when the dust radiation accumulated on the filter paper 2 is counted.

That is, the control device 10 is similar to the above.
At the start of measurement, the dust collection selection valve 5 is closed, and the bypass selection valve 8 is opened, so that the sampling gas is bypassed by the piping 7
And the boundary part 3a by controlling the dust collecting part driving part 11
After opening, the filter paper drive unit 9 is controlled to drive the filter paper 2 to send a new filter paper 2 to the dust collecting unit 3 to bring the dust collecting unit 3 to the state a shown in FIG. 3 (h). Control.

Further, the data processor 12 calculates and stores the background count rate based on the count rate in the state a (period Tb). Subsequently, the control device 10 opens the dust collecting selection valve 5 and closes the bypass selection valve 8 to remove the dust in the sampling gas from the filter paper as in the state c shown in FIG. 3 (j). The radioactivity detector 13 sends the dust count rate corresponding to the radiation of the dust to the data processing device 12 every predetermined time.

Here, the data processing device 12 ignores the received dust count rate until the predetermined idle time Td elapses. As a result, N in the numerator of the formula (1) is collected at the initial stage of dust collection.
Even if the ET count sharply increases, the dust collection time in the denominator of the equation (1) takes a value larger than the predetermined space time Td, and as a result, the dust radiation concentration obtained by the equation (1) is set to an appropriate value. can do.

After the elapse of the predetermined idle time Td, the data processor 12 receives the dust count rate and the background count rate BG described above every predetermined time, as described above.
Based on the above, the dust radiation concentration in the air at the measurement location is measured, and the display device 14 displays the measurement result.

Thereafter, as described above, the radiation measurement from the next time onward is executed. As described above, according to the second embodiment,
When the dust radiation concentration in the gas is obtained, the dust radiation concentration is calculated based on the dust radiation count value counted after the passage of the predetermined space time Td from the start of the collection. With the dead time of only the empty time Td, it is possible to correct the measurement error due to the count increase at the start of dust collection, and improve the accuracy of measurement of the dust radiation concentration.

Next, a radiation measuring method according to the third embodiment of the present invention will be described with reference to the time chart of FIG. The method of the present embodiment is different from the second embodiment in that a predetermined measurement start count rate Nd is provided instead of the predetermined free time Td, and the dust count rate received from the radiation detector 13 is the measurement start count rate Nd. The dust radiation concentration is calculated based on the dust count rate after exceeding.

Here, the control device 10 controls the dust collecting portion 3 to the state a shown in FIG. Further, the data processing device 12 calculates and stores the background count rate based on the count rate in the state a.

Subsequently, the control device 10 opens the dust collecting selection valve 5 and closes the bypass selection valve 8 to remove dust in the sampling gas from the filter paper as shown in FIG. 3 (j). The radioactivity detector 13 sends the dust count rate corresponding to the radiation of the dust to the data processing device 12 every predetermined time.

Here, the data processing device 12 ignores the dust count rate lower than the predetermined measurement start count rate Nd in order to prevent the measurement error due to the rapid increase of the radiation count rate as described above. It should be noted that a certain amount of dust collection time is required for the dust count rate at the initial stage of dust collection to exceed the measurement start count rate Nd.

As a result, even if the NET count in the numerator of the formula (1) sharply increases at the initial stage of dust collection, the dust collection time in the denominator of the formula (1) takes a large value, resulting in the formula (1). The dust radiation concentration obtained by can be set to an appropriate value.

Thereafter, radiation measurement is executed in the same manner as described above.
As described above, according to the third embodiment, when the dust radiation concentration in the gas is obtained, the dust radiation count value is counted after the predetermined count value Nd is exceeded after the start of the collection, and the dust radiation count value is counted. Since the radiation concentration is calculated, the measurement error due to the count increase at the start of dust collection is corrected by the dead time until the predetermined count value Nd is reached, and the accuracy of dust radiation concentration measurement is improved. be able to.

Next, a radiation measuring method according to the fourth embodiment of the present invention will be described with reference to the time chart of FIG. In the method of the present embodiment, in the apparatus having the same configuration as in FIG. 1, unlike the conventional method, the data processing apparatus 12 adds a predetermined addition value n to the original counting rate counted at the time of background counting, and The counting rate is calculated.

That is, by adding the added value n,
Since the background count rate used when obtaining the NET count is corrected to a value of an appropriate size, it is possible to correct a rapid increase in the count rate in the initial stage of dust collection and to accurately measure the dust radiation concentration. The added value n can be empirically obtained from the previous measurement record.

As described above, according to the fourth embodiment, as the process for obtaining the background count value, the background radiation is counted to obtain the original count value, and a predetermined addition value n is added to the original count value. Since the calculation processing to add is included, the measurement error due to the count increase at the start of dust collection can be corrected and the accuracy of dust radiation concentration measurement can be improved without causing dead time at the start of collection. it can.

Next, a radiation measuring method according to the fifth embodiment of the present invention will be described with reference to the time chart of FIG. Note that the method of the present embodiment is a technique for omitting the background measurement time and accurately measuring the dust radiation concentration in the device having the same configuration as in FIG. 1, unlike the prior art, and specifically, The data processing device 12 obtains the background count rate based on the dust measurement rate sent from the radiation detector 13, and calculates the dust radiation concentration based on the background count rate and the dust count rate.

Further, the data processing device 12 calculates the count value N1 by the first integration and the count value N2 by the next integration by integrating the dust count rate received from the radiation detector 13 every predetermined period. These count values N1, N2
Has a function of calculating the background count value BG by substituting in the formula of “BG = (3N1−N2) / 2” stored in advance. Further, the data processing device 12 subtracts the background count value BG from the count value N obtained by integrating the dust count rate for a predetermined period to obtain the NET count, and the N count is calculated.
It has the function of calculating the dust radiation concentration based on the ET count.

Here, as shown in FIG. 7, the data processing device 12 calculates the initial count value N1 by integrating the dust count rate for a predetermined period from the start of dust collection. At this time, the count value N1 is equivalent to the area of the trapezoid surrounded by a1, b1, c2, a2, and a1.

Similarly, the data processor 12 integrates the dust count rate for a predetermined period after the completion of the integration of the count value N1 to obtain the next count value N2. The count value N2
Is equivalent to the area of a trapezoid surrounded by a2, c2, a3 and a2.

Here, when the first count value N1 is subtracted from the next count value N2, the count value (N2-N1) accumulated in the next predetermined period is obtained. This count value (N2-N1) is equivalent to the area of the parallelogram enclosed by b2, c2, d3, c3 and b2.

Then, by simple geometrical consideration, when the count value (N2-N1) is divided into two, the count value {(N2-N1) / 2} accumulated in the first predetermined period is obtained.
In addition, the count value {(N2-
N1) / 2} is equivalent to the area of the triangle surrounded by b1, c2, b2, and b1.

Therefore, the count value accumulated in the first predetermined period from the count value N1 of the first predetermined period {(N2-N1) /
By subtracting 2}, the background count value BG in the predetermined period can be obtained.

That is, the data processor 12 calculates the background count value BG by the following equation (2). BG = N1- (N2-N1) / 2 = (3N1-N2) / 2 (2) Hereinafter, as described above, the data processing device 12 obtains the count value N obtained by integrating the dust count rate for a predetermined period. The background count value BG is subtracted from this to obtain the NET count, and the dust radiation concentration is calculated based on this NET count.

As described above, according to the fifth embodiment, when the dust radiation concentration in the gas is obtained, the dust radiation accumulated on the filter paper 2 from the start of the collection is counted, and the counting result is kept constant. Count value N for the first integration by integrating for each period
1 and the count value N2 by the next integration are obtained, and these first and next count values N1 and N2 are calculated as “BG = (3N1-N
2) / 2 ”is substituted into the formula and the background count value BG
Is calculated and the background count value BG is subtracted from the dust radiation count value, and the dust radiation concentration is calculated based on the subtraction result, so that there is no time to measure the background count value BG. Therefore, the measurement time can be shortened, and the measurement error due to the count increase at the start of dust collection can be corrected to improve the accuracy of measurement of the dust radiation concentration.

In the first embodiment, after the dust collecting portion 3 is set to the state b shown in FIG. 3 (i), the dust in the sampling gas is not accumulated on the filter paper 2, so the dust collecting selection valve 5 is set. The case where the bypass selection valve is set to the closed state and the bypass selection valve is set to the open state has been described. However, the state is not limited to this, and after the state is set to the state b, the suction pump 6 is stopped to prevent accumulation of dust on the filter paper 2. However, the same effects can be obtained by implementing the present invention in the same manner. In addition, the present invention can be modified in various ways without departing from the scope of the invention.

[0067]

As described above, according to the present invention, it is possible to provide a radiation measuring method capable of correcting a measurement error due to a count increase at the start of dust collection and improving the accuracy of measurement of dust radiation concentration.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a dust radiation monitor according to a first embodiment of the present invention.

FIG. 2 is a time chart for explaining the operation in the embodiment.

FIG. 3 is a schematic diagram for explaining the operation in the embodiment.

FIG. 4 is a time chart for explaining a radiation measuring method according to the second embodiment of the present invention.

FIG. 5 is a time chart for explaining a radiation measuring method according to the third embodiment of the present invention.

FIG. 6 is a time chart for explaining a radiation measuring method according to a fourth embodiment of the present invention.

FIG. 7 is a time chart for explaining a radiation measuring method according to a fifth embodiment of the present invention.

FIG. 8 is a time chart showing the operation of a conventional dust radiation monitor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sampling piping, 2 ... Filter paper, 2a ... Unwinding roller, 2b ... Winding roller, 3 ... Dust collecting part, 3a ... Boundary part,
4 ... Dust collection piping, 5 ... Dust collection selection valve, 6 ... Suction pump, 7 ...
Bypass piping, 8 ... Bypass selection valve, 9 ... Filter paper drive unit,
10 ... Control device, 11 ... Dust collection part drive part, 12 ... Data processing device, 13 ... Radiation detector, 14 ... Display part.

Claims (5)

[Claims] 1. A radiation measuring method for obtaining a dust radiation concentration in the gas by sucking a gas containing dust through a filter paper and counting radiation emitted from the dust collected on the filter paper, When sucking the gas, the circumference of the filter paper is filled with the atmosphere of the gas, the suction is interrupted to count the radiation of the atmosphere gas, and the suction is performed when the counting of the radiation of the atmosphere gas is finished. To collect dust on the filter paper, count radiation of the dust collected, subtract the radiation radiation count of the atmosphere gas from the radiation radiation count of the dust, and obtain the subtraction result. A radiation measuring method, characterized in that the dust radiation concentration is calculated based on the above. 2. A gas containing dust is sucked through a filter paper, radiation emitted from the dust collected on the filter paper is counted, and the dust radiation concentration in the gas is calculated based on the dust radiation count value. In the radiation measurement method for determining the dust radiation concentration in the gas, the dust radiation concentration is calculated based on the dust radiation count value counted after a predetermined time has elapsed from the start of the collection. A radiation measuring method characterized by: 3. A gas containing dust is sucked through a filter paper, the radiation emitted from the dust collected on the filter paper is counted, and the dust radiation concentration in the gas is counted based on this dust radiation count value. In the radiation measurement method for determining, in determining the dust radiation concentration in the gas, based on the dust radiation count value counted after exceeding a predetermined count value from the start of the collection, the dust radiation concentration, A radiation measuring method characterized by calculating. 4. The background radiation is counted to obtain a background count value, a gas containing dust is sucked through a filter paper, and the radiation emitted from the dust collected on the filter paper is counted. By subtracting the background count value from the dust radiation count value, in a radiation measurement method for determining the dust radiation concentration in the gas, as the process for determining the background count value, counting the background radiation A radiation measuring method comprising a calculation process of obtaining a count value and adding a predetermined added value to the original count value. 5. A gas containing dust is sucked through a filter paper, the radiation emitted from the dust collected on the filter paper is counted, and the dust radiation concentration in the gas is counted based on this dust radiation count value. In the radiation measuring method for determining, when determining the dust radiation concentration in the gas, counting the radiation of the dust accumulated on the filter paper from the start of the collection, and integrating the counting result at regular intervals. The count value N1 obtained by the first integration and the count value N2 obtained by the next integration are obtained, the background count value BG is obtained by substituting these first and next count values N1, N2 into the following equation, and this background count value BG is calculated. A radiation measuring method, comprising: subtracting from the dust radiation count value, and calculating the dust radiation concentration based on the subtraction result. BG = (3N1-N2) / 2