JP2002365367A - Monitoring post system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a monitoring post system capable of measuring the space dose of atmospheric radioactivity and identifying the nuclide of radiation to estimate the origin of radiation. SOLUTION: This monitoring point system for measuring atmospheric radioactivity comprises a γ-ray nuclide analyzing detector 1 and a measurement system therefor 7, an α-ray nuclide measuring detector 2 and a measurement system therefor 8, an α-nuclide analyzing detector 3 and a measurement system therefor 9, a tritium-measuring liquid scintillation counter 4, and a control means 12 for performing transfer of measurement data signal and control signal with the liquid scintillation counter 4 and each measurement systems 7, 8, 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monitoring post system which is installed around a nuclear facility and measures environmental radioactivity.

[0002]

2. Description of the Related Art A conventional monitoring post system generally has a configuration as shown in FIG. That is,
NaI (sodium iodide) detector 211 and its measurement system 212, I
A C (ion chamber) detector 213 and its measuring system 214, a telemeter device 215, and a central management station 216 connected to the telemeter device 215 by wire or wirelessly.
The detector 213 detects high levels of radioactivity and the NaI detector 21
1 is to detect low levels of radioactivity and perform low resolution simple nuclide analysis.

[0003]

The conventional monitoring post system measures the air dose of radioactivity and can perform very simple energy discrimination. However, the origin of the radioactivity (artificial radioactivity or natural radioactivity) Ability) cannot be estimated.

Accordingly, an object of the present invention is to provide a monitoring post system capable of measuring the air dose of radioactivity in the atmosphere, identifying the nuclide of the radioactivity, and estimating the origin of the radioactivity. .

[0005]

In order to solve the above-mentioned problems, a monitoring post system according to a first aspect of the present invention is a monitoring post system for measuring radioactivity in the atmosphere, comprising: a detector for gamma-ray nuclide analysis; System, detector for α-ray measurement and its measurement system, detector for α-nuclide analysis and its measurement system, liquid scintillation counter for tritium measurement, liquid scintillation counter and each of the measurement systems and measurement data And control means for transmitting and receiving signals and control signals.

According to the monitoring post system of the present invention, radioactivity analysis in the atmosphere (including rainwater) becomes possible, the origin of radioactivity (natural or artificial) can be understood, and the accuracy of air dose rate measurement has been improved. The effectiveness of peripheral monitoring can be improved.

According to a second aspect of the present invention, in the first aspect of the invention, the detector for γ-ray nuclide analysis is a germanium detector, the detector for α-ray measurement is a zinc sulfide detector, and the α-nuclide analysis is performed. Is a semiconductor detector. The monitoring post system of the present invention can efficiently detect and measure γ-ray nuclides, α-rays, α-nuclides and tritium in the atmosphere.

According to a third aspect of the present invention, in the first aspect, the rainwater is filtered by a filter, and the radioactivity of the filter is measured. The monitoring post system according to the present invention can efficiently detect the radioactivity of dust contained in rainwater.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the filter has a belt-like shape, and is provided with a waterproof treatment for each rainwater filtering area. ADVANTAGE OF THE INVENTION In the monitoring post system of this invention, the collection date of the dust in rainwater can be classified correctly.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A monitoring post system according to an embodiment of the present invention will be described with reference to FIGS. The overall configuration of the monitoring post system according to the embodiment of the present invention is as shown in FIG. That is,
Ge (germanium) detector 1 for γ-ray nuclide analysis and its measurement system 7, ZnS (zinc sulfide) detector 2 for α-ray measurement
And its measurement system 8, SSD (semiconductor) for α nuclide analysis
Detector 3 and its measurement system 9, liquid scintillation counter 4 for tritium measurement, IC detector 5 and its measurement system
10, NaI detector 6 and its measurement system 11, and Ge measurement system 7
Is connected to the output side from the to the NaI measurement system 11 by wire or wireless, and the output signal of the Ge measurement system 7 is input and
It comprises a personal computer 12 for controlling the Ge measuring system 7 and the like. The Ge measurement system 7 has an amplifier A / D converter, an input / output unit, and the like.

The monitoring post system of this configuration can perform gamma nuclide analysis and alpha nuclide analysis on the radioactivity in the air (including rainwater) at dispersed points, and estimates the origin of the radiation dose in the area. And also the measurement of tritium.

Next, measurement of rainwater radioactivity will be described. FIG. 2 shows a configuration for rainwater collection. In the present embodiment,
Rainwater catch that prevents foreign matter such as dust from entering during normal operation
The lid 22 of 21 is opened by the lid opening / closing mechanism 23 when it rains, and the rainwater accumulates in the rainwater receiver 21 and is transferred to the measurement system by the pump 24. A washing nozzle 26 is installed in the rainwater receiver, and pure water is supplied by the pump 25 for washing before, during, or after collection of the rainwater.

FIG. 3 shows a filtering apparatus for collecting solid components for measuring radioactivity in rainwater. The filtration device includes a rainwater filter 31, a filter 32, a vacuum pump 34 for reducing the pressure to increase the filtration speed, a flexible vacuum hose 33 for connection, and a drain valve 35. Filter 32
Needs to be replaced for each filtration, an example of the mechanism is shown in FIG.

As shown in FIG. 4, when the filter is replaced, the filter upper part 44 and the filter lower part 45 are separated from each other, and the filter lower part 45 is separated.
The 45 slides on the moving rail 41 so that the filter can be easily attached. After the filter is set, the lower filter 45 returns to its original position, and the upper filter 44 and O-ring 42
Are connected to maintain a vacuum. For this purpose, a lifting mechanism 43 is provided. This mechanism can be used not only for rainwater but also for dust collection.

FIG. 5 shows an example in which an air introduction valve 51 for introducing drying air is installed in the filtration device shown in FIG. 3, and is particularly effective for α-ray measurement and α-nuclide analysis. In this apparatus, the drying air has an air flow in the same direction as that at the time of filtration so as not to cause the filtered material to fly up. Further FIG.
Shows an example in which a high-performance filter 61 is installed so as not to introduce dust.

FIG. 7 shows a continuous filter paper 71 used in a rainwater filtration system. In order to prevent the dissolved radioactive element from affecting the next filter portion, the continuous filter paper 71 is coated with a wax or the like at regular intervals (the length used for one measurement) to make the wax portion 72 water-repellent. Is provided.

FIG. 8 shows a configuration for measuring γ-rays in the entire rainwater. That is, the Ge detector 82 and the flow cell 81
A Ge measurement system 83 is provided, and the control system is a control system equipped with a program capable of continuously performing nuclide analysis. This makes it possible to perform nuclide analysis continuously.

FIG. 9 shows a configuration using a Ge detector as an example of an apparatus for performing nuclide analysis. Ge detector 91 cools using liquid nitrogen 93 contained in Dewar bottle 92. However, liquid nitrogen 93 evaporates during use and evaporates,
Cooling head 94 and compressor 9 installed in Dewar bottle 92
6, refrigerant hose 95 and controller 9 to connect them
Liquid nitrogen 93 using a nitrogen evaporation prevention device consisting of 7
To cool.

With this configuration, it is possible to operate the vehicle unattended. Also, at the time of power failure, by cooling with residual liquid nitrogen, measurement can be performed immediately after power recovery. If there is enough time after power restoration, other cooling methods such as cooling using a direct compressor can be used. Further, other than the Ge detector, any detector having a good resolution near normal temperature can be used.

Fig. 2 shows the configuration for measuring the radioactivity of the filter.
See Figure 10. The measurement system consists of a detector 101 (such as ZnS) and its measurement system 102 for α-ray measurement, and a Ge detector 103 and its measurement system for gamma-ray nuclide analysis measurement.
It is installed at a position sandwiching 32. In the measurement of α-rays, in order to prevent α-rays from being attenuated by the filter, drying is performed using a surface collection type filter such as a millipore or a membrane filter, and the measurement is always performed from the surface side (collection side). The drying mechanism for this may be that shown in FIG.

FIG. 11 shows a configuration for preventing the influence of Rn (radon) and Tn (tron) in the air supplied for drying the filter 32 on α-ray measurement. That is, dust contained in the air from the outside is removed in advance by a high-performance filter 111 such as HEPA (high-performance particle filter), and stored in a storage tank 113 that stores the air this time via a pump 112 and a valve 114. Here, the air after storing for a certain period and attenuating Rn and Tn is supplied to the valve 11 on the outlet side.
5 is opened and used by pump 116 for drying.

The plurality of storage tanks 113 are sequentially used, and these are controlled by the controller 117. Also, in order to exclude the effects of daughter nuclides,
A high-performance filter 118 such as HEPA is also installed at the air supply port.

FIG. 12 shows a configuration for measurement at the time of α-nuclide analysis. In the α-nuclide analysis, the resolution is reduced due to the influence of air between the α-nuclide analysis detector 123 such as an SSD detector and the filter 32, and therefore, it is necessary to evacuate during measurement. Therefore, the filter 32 and the α-nuclide analysis detector 123 are installed in the vacuum vessel 121.

In this configuration, it is necessary to replace the filter 32 in the vacuum vessel 121. For example, the mechanism shown in FIG. 4 is used, and the vacuum is maintained by the O-ring 122. In order to prevent the sample from being scattered during the evacuation, a filter mounting base 125 and the like are provided so that evacuation can be performed from the back side of the filter 32. In order to prevent the evacuation time from being lengthened by freezing of the filter 32, the evacuation is performed after drying with dry air.

FIG. 13 shows the configuration of a water sampling apparatus for measuring tritium in the atmosphere by an unmanned person. Air from which dust components have been removed by a filter 136 is sent to a water collector 131 by a pump 135, and water in the air condenses into a collector cooling unit 132 cooled by a cooling unit 133. It collects in the lower part of the collector 131. This water level is observed by the water level detector 134, and when the water level exceeds a certain level, the valve 137 is opened and moved to the water receiving section 138.
Thereafter, a predetermined amount of water is sent to the vial via the pump 139.

For cooling the cooling unit 133, a cooler using a compressor, a cooler using a Peltier effect having no moving parts, or the like is used. Efficiency can be improved by covering the entire water collector 131 with a heat insulating material. Depending on the season, the humidity may be low, in which case a more efficient method is needed.

FIG. 14 shows a pressurized type water sampling apparatus. In this water sampling apparatus, the pressure in the water collector 131 is increased by a pressure pump 141.
The signal of the pressure gauge 142 is taken into the controller 144, and the pressure is controlled by adjusting the opening of the needle valve 143. The pressure is set by calculating the saturated vapor pressure in the controller 144 from the output value of the hygrometer 145.

As a more efficient apparatus for collecting atmospheric moisture, there is an apparatus using an adsorbent packed tower 151 shown in FIG. In FIG. 9A, the moisture adsorbed at room temperature is expelled at a high temperature by using the heater 152, so that the amount of moisture in the air can be increased and the water can be collected more efficiently at the same cooling temperature. In addition,
Heat loss is prevented by winding a heat insulating material 153 around the heater. Further, as shown in FIG. 13B, there is a method of increasing the adsorption capacity by using a cooler 154 during adsorption. As a treatment method after moisture adsorption, while keeping the adsorbent at a low temperature, the system of the water collector 131 is separated from the adsorbent filling tower 151 by valves installed at the front and rear, and a vacuum is applied in a short time, and then the adsorbent is charged. Tower 15
Moisture is transferred to the water collector by heating 1.

The measurement of tritium contained in the atmospheric moisture contained in the vial in this manner is performed by a vial measurement system 164 shown in FIG. The vial measurement system 164 includes an automatic lid device 161 that automatically covers the vial 130, and it is necessary to mix water and a liquid scintillator to measure tritium, but a shaker 162 for that purpose. And liquid scintillation counter 1
It consists of 63, and the sample is automatically transferred to the series for measurement.

As an example, as shown in FIG. 17, a general detector generally has energy dependence of detection sensitivity. Therefore, when the energy of the γ-rays to be subjected to the air dose changes, a phenomenon occurs in which the count differs for the same number of γ-rays. However, since the radiation type does not change rapidly, the energy distribution of γ-rays can be measured by measuring for a long time with a Ge detector and accurately measuring each nuclide,
Correction of other detectors is possible. In addition, since the Ge detector has a low dose, measurement can be performed efficiently by using a Ge detector having a high relative efficiency.

As shown in FIG. 18, the data transmission between the monitoring post system 181 and the central management station 182 is wireless. Thus, the monitoring post system according to the present embodiment can be used even in a place where cable laying is difficult, such as a mountain or a remote island.

Since water is not available in the mountains or on remote islands, it is necessary to store and supply rainwater on the roof or near the monitoring post as the water required for analysis. FIG. 19 shows an apparatus for self-supplying cleaning water. In this apparatus, rainwater is collected by a large rainwater receiver 191, passed through a filter 193, and stored in a storage tank 194. When not in use, cover with lid 192 to prevent dust. If it is accumulated too much, it is washed away from the overflow pipe 195, but a simple filter 198 is installed to prevent the inflow of dust from this part.

Although normal cleaning can be used as it is, in a tritium measurement system, the measurement is affected by a very small amount of contaminants. Therefore, a pure water production apparatus 201 as shown in FIG. 20 is used. That is, the water stored in the storage tank 194 is sent to the pure water production apparatus 201 by the pump 196. The pure water production apparatus 201 produces pure water through processes such as reverse osmosis, ion exchange, and activated carbon adsorption. Then, it is transferred and stored in the pure water storage tank 203 by the pump 202,
Send out at 04 for a given purpose. Although the above is a method of self-supply of water, unattended operation can be performed by using a combination of a solar cell and a fuel cell for electricity.

Each of the above measuring devices is operated automatically, but can be operated by a command from the central management station as appropriate according to a change in weather or a change in surrounding conditions, and more detailed measurement can be performed.

[0035]

According to the monitoring post system of the present invention, it is possible to analyze the radioactivity in the atmosphere (including rainwater), to understand the origin of the radioactivity (natural or artificial), and to improve the accuracy of the air dose rate measurement. And the effectiveness of peripheral monitoring can be increased.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of a monitoring post system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a rainwater collecting unit in the monitoring post system according to the embodiment.

FIG. 3 is a diagram showing a rainwater filter filtering unit in the monitoring post system of the embodiment.

FIG. 4 is a diagram showing a filter replacement mechanism in the monitoring post system of the embodiment.

FIG. 5 is a diagram showing a filter drying mechanism in the monitoring post system according to the embodiment.

FIG. 6 is a diagram showing a dry air filtration device in the monitoring post system of the embodiment.

FIG. 7 is a diagram showing a filter paper for water filtration in the monitoring post system of the embodiment.

FIG. 8 is a diagram showing a flow cell use mechanism in the monitoring post system of the embodiment.

FIG. 9 is a diagram showing a liquid nitrogen evaporation preventing device in the monitoring post system of the embodiment.

FIG. 10 is a diagram showing an α measuring device in the monitoring post system of the embodiment.

FIG. 11 is a diagram showing an apparatus for removing the influence of Rn and Tn during drying in the monitoring post system of the embodiment.

FIG. 12 is a diagram showing an automatic α-nuclide analyzer in the monitoring post system of the embodiment.

FIG. 13 is a diagram showing a device for collecting moisture in the air in the monitoring post system of the embodiment.

FIG. 14 is a diagram showing a pressurized moisture collecting device in the monitoring post system of the embodiment.

FIG. 15 is a diagram showing a moisture collecting device using an adsorbent in the monitoring post system of the embodiment.

FIG. 16 is a diagram showing a vial measuring system in the monitoring post system of the embodiment.

FIG. 17 is a diagram showing a relationship between detector sensitivity and γ-ray energy in the monitoring post system according to the embodiment.

FIG. 18 is a diagram showing a configuration for transmitting information in the monitoring post system of the embodiment.

FIG. 19 is a diagram showing a utility water collection device in the monitoring post system of the embodiment.

FIG. 20 is a diagram showing a pure water production apparatus in the monitoring post system of the embodiment.

FIG. 21 is a diagram showing a conventional monitoring post system.

[Explanation of symbols]

1 ... Ge detector, 2 ... ZnS detector, 3 ... SSD detector, 4 ... Liquid scintillation counter, 5 ... IC detector, 6 ... NaI
Detector, 7: Ge measurement system, 8: ZnS measurement system, 9: SSD measurement system, 10: IC measurement system, 11: NaI measurement system, 12: PC, 21
… Rain water catcher, 22… lid, 23… lid opening and closing mechanism, 24… pump, 25
... Washing water pump, 26 ... Washing nozzle, 31 ... Rainwater filter, 32 ... Filter, 33 ... Vacuum hose, 34 ... Vacuum pump, 35 ... Drain valve, 41 ... Movable rail, 42 ... O-ring, 43 ...
Push-up mechanism, 44… Filter upper part, 45… Filter lower part, 51… Air introduction valve, 61… High performance filter, 71… Continuous filter paper,
72… wax part, 81… float, 82… Ge detector, 83…
Measurement system, 91: Ge detector, 92: Dewar bottle, 93: Liquid nitrogen, 94: Cooling head, 95: Refrigerant hose, 96: Compressor, 97: Controller, 101: α-ray detector, 102: α-ray measurement System, 103… Ge detector, 104… Ge measuring system, 111… High performance filter, 112… Pump, 113… Storage tank, 11
4… Valve, 115… Valve, 116… Pump, 117… Controller, 118… High performance filter, 121… Vacuum vessel, 122… O
Ring, 123… Detector for α nuclide analysis, 124… Measurement system, 125
… Filter stand, 130… Vial bottle, 131… Water collector, 132… Water collector cooling section, 133… Cooling section, 134… Water level detector, 135… Pump, 136… Filter, 137… Valve, 1
38 ... Water receiving unit, 139 ... Pump, 141 ... Pressure pump, 142 ... Pressure gauge, 143 ... Needle valve, 144 ... Controller, 145
... hygrometer, 151 ... adsorbent packed tower, 152 ... heater, 153 ...
Moisturizer, 154 ... cooler, 161 ... automatic lid device, 162 ... shaker, 163 ... liquid scintillation counter, 164 ... vial measuring system, 181 ... monitoring post system, 182 ... central management station, 191 ... rainwater catch, 192 ... lid, 193 ... filter, 194 ... storage tank, 195 ... overflow pipe, 196 ... pump, 197 ... drain valve, 198 ... filter, 2
01 ... pure water production equipment, 202 ... pump, 203 ... pure water storage tank, 204 ... valve, 211 ... NaI detector, 212 ... NaI measurement system, 213 ... IC detector, 214 ... IC measurement system, 215 ... telemeter device , 216 ... Central Management Bureau.

Continued on front page F term (reference) 2G075 AA01 CA02 CA50 DA08 EA01 FA18 FA20 FC03 FC12 2G088 EE10 EE12 EE13 EE21 EE25 EE26 FF04 FF05 FF06 FF17 GG10 GG12 GG21 HH03 HH07 HH08 HH09 KK20 KK28

Claims (4)

[Claims] 1. A monitoring post system for measuring radioactivity in the atmosphere, comprising: a detector for γ-ray nuclide analysis and its measurement system; a detector for α-ray measurement and its measurement system; A monitoring post system comprising: a detector and a measuring system thereof; a liquid scintillation counter for measuring tritium; and a control means for transmitting / receiving a measurement data signal and a control signal to / from the liquid scintillation counter and each of the measuring systems. . 2. The detector for gamma-ray nuclide analysis is a germanium detector, the detector for α-ray measurement is a zinc sulfide detector, and the detector for α-nuclide analysis is a semiconductor detector. The monitoring post system according to claim 1, wherein 3. The monitoring post system according to claim 1, wherein the rainwater is filtered by a filter, and the radioactivity of the filter is measured. 4. The monitoring post system according to claim 3, wherein the filter has a band-like shape, and is subjected to a waterproof treatment every time the rainwater is filtered.