JP3779374B2 - Radiation detection sampler - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radiation detection sampler for calibrating an exhaust stack radiation monitor in a nuclear facility.
[0002]
[Prior art]
An exhaust pipe radiation monitor is installed in an exhaust pipe in a nuclear facility for the purpose of monitoring whether or not a radioactive substance is contained in the exhaust gas.
Conventionally, in order to calibrate such an exhaust stack radiation monitor, a radiation detection sampler that performs nuclide analysis of a radioactive substance contained in a sampling gas of the exhaust stack radiation monitor has been used.
[0003]
This sampler for radiation detection is used only for nuclide analysis of radioactive materials contained in gas. Liquid samples and solid samples are collected by other equipment in an exhaust stack radiation monitor. Using a nuclide analyzer.
[0004]
[Problems to be solved by the invention]
As described above, since the conventional sampler for radiation detection can only perform nuclide analysis of only gas, each facility for performing nuclide analysis with a separate nuclide analyzer is required for liquid samples and solid samples other than gas.
[0005]
On the other hand, when measuring the radioactivity of a radioactive substance contained in a continuously flowing liquid, a sample chamber dedicated to the liquid is used, but when the flow rate of the liquid flowing in the sample chamber is high, the radioactive substance is not contained. There is a problem that measurement accuracy is poor because it does not stay in the sample chamber for a long time.
[0006]
A first object of the present invention is to provide a radiation detection sampler that can perform nuclide analysis of liquid samples other than gas and solid samples with the same radiation detector and has a wide utilization range of equipment.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention constitutes a radiation detection sampler by the following means.
The invention corresponding to claim 1 includes a shielding container, a radiation detector installed at the bottom of the shielding container, and a fluid sample installed in the shielding container so as to be movable up and down above the radiation detector. A flexible pipe for supplying and discharging the gas is connected through the inside and outside of the shielding container, and a chamber having a recess provided at a position facing the radiation detector, and between the radiation detector and the recess. A detachable sample stage provided, and in a state where the sample stage is arranged, the chamber moves above the radiation detector, and the sample in the chamber is used as a detection target. The platform is removed and the chamber is moved downward so that the radiation detector is inserted into the recess.
[0009]
Therefore, in the sampler for radiation detection having such a configuration, when the sample gas is introduced by the sample chamber and the nuclide analysis of the gas is not performed, the nuclide analysis of the liquid or solid sample is performed by the same radiation detector. As a result, the range of use of the facilities is widened.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view showing a configuration example showing a first embodiment of a radiation detection sampler according to the present invention.
[0013]
In FIG. 1 (a), reference numeral 1 denotes a shielding container made of lead, copper or the like installed on a gantry 2, and a cylindrical sample table 3 is installed at the substantially central portion of the bottom surface in the shielding container 1. A liquid or solid analysis sample 5 is placed on a support 4 provided in the middle of the sample stage 3.
[0014]
Further, a germanium semiconductor detector (hereinafter referred to as Ge detector) 6 is provided below the support 4 in the sample stage 3, and this Ge detector 6 is provided through the bottom of the shielding container 1 from the gantry 1 side. The pipe-shaped guide 7 is attached.
[0015]
On the gantry 1 side of the guide 7, a preamplifier 8 is provided which is electrically connected to a cable existing in the guide 7 and amplifies a radiation detection signal detected by the Ge detector 6. Is fitted with a cooling vessel 9 containing liquid nitrogen.
[0016]
On the other hand, a sample chamber 10 is provided in the shielding container 1, and this sample chamber 10 is supported by an elevating mechanism 11 that is vertically attached to the bottom surface of the shielding container 1 so as to be movable in the vertical direction.
[0017]
The sample chamber 10 has a recess 10a formed in a portion corresponding to the Ge detector 6, and the Ge detector 6 can be inserted into the recess 10a. Further, a flexible pipe 12 for filling the sample chamber 10 with the sample gas and a flexible pipe 13 for discharging the sample gas in the sample chamber 10 to the outside are arranged through the appropriate portions of the side wall of the shielding container 1. In addition, the end of the flexible pipe 12 is connected to the lower part of the sample chamber 10, and the end of the flexible pipe 13 is connected to the center of the upper surface of the sample chamber 10.
[0018]
These flexible pipes 12 and 13 can follow up and down movement of the sample chamber 10.
Next, the operation of the radiation detection sampler configured as described above will be described.
[0019]
When analyzing a liquid sample or a solid sample, as shown in FIG. 1A, the sample chamber 10 is moved above the sample stage 3 by the lifting mechanism 11 and is collected on the sample stage 3 by, for example, a tritium recovery device. An analysis sample 5 such as a liquid sample or a solid sample collected by a dust sampler (filter paper) or an iodine filter (activated carbon adsorption filter) is placed.
[0020]
In this way, the Ge detector 6 detects the radiation contained in the liquid or solid sample existing above it, and the detection signal is amplified by the preamplifier 8 and then transmitted to an analyzer (not shown) such as a multi-channel analyzer. The nuclide analysis is performed.
[0021]
On the other hand, when performing a gas analysis, the sample stage 3 and the analysis sample 5 shown in FIG. 1A are taken out to make only the Ge detector 6, and the sample chamber 10 is moved downward by the elevating mechanism 11. As shown in b), it stops at the position where the Ge detector 6 is inserted into the recess 10a formed in the sample chamber 10.
[0022]
In this state, the nuclide analysis can be performed by introducing the sampling gas into the sample chamber 10 through the flexible pipe 12 and transmitting the detection signal from the Ge detector 6 to, for example, a multi-channel analyzer as described above.
[0023]
As described above, in the first embodiment, the sample chamber 10 that is moved up and down by the lifting mechanism 11 is provided in the shielding container 1, and when the nuclide analysis of the sample gas is performed, the sample chamber 10 is placed above the Ge detector 6. When the gas analysis is not performed, the sample chamber 10 is moved upward to place the sample stage 3 on the Ge detector 6 and the liquid or solid sample 5 is placed on the sample stage 3. Since the nuclide analysis can be performed, the range of use of the equipment is widened, and the equipment for performing the nuclide analysis using a separate nuclide analyzer corresponding to each of liquid and solid samples in addition to gas becomes unnecessary. .
[0024]
In the first embodiment, the Ge detector 6 is cooled by liquid nitrogen accommodated in the cooling container 9. However, some radiation detectors do not necessarily have a cooling function by liquid nitrogen.
[0025]
By the way, in the first embodiment, the case where nuclide analysis of a gas, liquid, and solid sample is performed by one radiation detection sampler has been described, but the radioactivity of a radioactive substance contained in a continuously flowing liquid is measured. Therefore, it is not possible to apply the method for nuclide analysis, so a sample chamber dedicated to liquid is required.
[0026]
FIG. 2 is a cross-sectional view showing a liquid-specific radiation detection sampler according to a second embodiment of the present invention.
In FIG. 2, reference numeral 21 denotes a lead shielding container. The liquid flows into the shielding container 21 through an inlet pipe 22 penetrating the lower part of one side wall, and circulates inside the upper part of the other side wall. A sample chamber 24 is provided so as to flow out to the outside through an outlet pipe 23 provided therethrough.
[0027]
The sample chamber 24 is formed with a recess 24a bulging inward from the substantially center of the upper surface of the cylinder whose both ends are closed, and a radiation detector 25 is inserted into the recess 24a.
[0028]
In addition, a hollow fiber membrane filter 26 that permeates liquid and adsorbs a radioactive substance is provided in the sample chamber 24. This hollow fiber membrane filter 26 is a bundle of thin tubular hollow fiber membranes as shown in FIG. 3, and is configured such that liquid that has permeated into the interior from the surface is drained through the hollow portion.
[0029]
In the radiation detection sampler having such a configuration, the liquid that has flowed into the sample chamber 24 from the inlet pipe 22 penetrates from the surface of the hollow fiber membrane filter 26 and is discharged outside through the outlet pipe 23 through the hollow portion. At this time, the radioactive material that did not pass through the hollow fiber membrane is adsorbed on the surface of the hollow fiber membrane.
[0030]
Therefore, even if the flow rate of the liquid flowing in the sample chamber 24 is high, only the radioactive substance contained in the liquid can be retained for a long time on the surface of the hollow fiber membrane, so that the radiation measurement accuracy by the radiation detector 25 can be increased. Can be improved.
[0031]
According to the second embodiment, by providing the hollow fiber membrane filter 26 in the sample chamber 24, only the radioactive substance contained in the liquid can be hollow fiber without slowing the flow rate of the continuously flowing liquid. It can be adsorbed on the surface of the film and can stay in the sample chamber 24 for a long time, and the radiation dose to the radiation detector 25 increases.
[0032]
This means that when the object to be measured is a liquid with a low radioactivity level, the radioactivity value / background radioactivity value ratio (S / N ratio) measured by the radiation detector is improved, and the measurement accuracy is improved. it can.
As described above, the second embodiment has been described on the assumption that the measurement target is a liquid, but it can also be applied to a gas.
[0033]
【The invention's effect】
As described above, according to the sampler for radiation detection according to the present invention, nuclide analysis of liquid samples other than gas and solid samples can be performed by the same radiation detector, and the utilization range of equipment can be expanded.
[0034]
In addition, according to the sampler for radiation detection dedicated to fluid, even if the object to be measured is a fluid with a low level of radioactivity, the substance to be measured and the fluid are separated by the hollow fiber membrane filter provided in the sample chamber, Since the radioactive substance can be retained in the sample chamber, the radioactivity can be accurately measured even if the flow rate of the fluid flowing through the sample chamber is high.
[Brief description of the drawings]
1A and 1B show a first embodiment of a radiation detection sampler according to the present invention, in which FIG. 1A is a sectional view when analyzing a liquid or solid sample, and FIG. 1B is an analysis of a gas sample; FIG.
FIG. 2 is a cross-sectional view showing a second embodiment of a liquid detection sampler for liquids according to the present invention.
3 is an enlarged perspective view showing a portion A of the hollow fiber membrane filter of FIG. 2. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Shielding container 2 ... Lead 3 ... Sample stand 4 ... Support 5 ... Solid analysis sample 6 ... Ge detector 7 ... Guide 8 ... Preamplifier 9 ... Cooling vessel DESCRIPTION OF SYMBOLS 10 ... Sample chamber 11 ... Elevating mechanism 12, 13 ... Flexible piping 21 ... Lead shielding container 22 ... Inlet piping 23 ... Outlet piping 24 ... Sample chamber 24a ... Concave 25 ... Radiation detector 26 …… Hollow fiber membrane filter

Claims (1)

A shielding container, a radiation detector installed at the bottom of the shielding container, a flexible pipe that is installed in the shielding container so as to be movable up and down above the radiation detector, and that supplies and discharges a fluid sample; A chamber that is connected through the inside and outside of the shielding container, and has a recess provided at a position facing the radiation detector, and a removable sample stage provided between the radiation detector and the recess. When the sample stage is arranged, the chamber moves above the radiation detector, and when the sample in the chamber is to be detected, the sample stage is removed and the radiation detector is removed. The radiation detection sampler is characterized in that the chamber is moved downward so that is inserted into the recess .

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