JPH09288185A - Sampler for radiation detection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable nuclide analysis of a liquid sample except for gas and a solid sample with the same radiation detector by performing nuclide analysis measuring of the liquid or solid sample with the same radiation detector when a gas sample is introduced from a sample chamber and nuclide analysis measuring is not performed. SOLUTION: When a liquid sample or a solid sample, for instance is analyzed, a sample chamber 10 is moved upward a sample base 3 by a lift mechanism 11, and an analysis sample 5 such as the liquid sample or a dust sample sampled from a tritium collection device and the solid sample sampled from an iodine filter is mounted on the sample base 3. Thereby, a Ge detector 6 detects radiation containing the liquid sample or the solid sample existing on the upper part, after its detection signal is amplified with a preamplifier 8, it is transmitted to an analyzer, for instance, a multi-channel analyzer, and nuclide analysis is performed therein.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation detection sampler for calibrating a stack radiation monitor in a nuclear facility.

[0002]

2. Description of the Related Art An exhaust stack radiation monitor is installed in an exhaust stack in a nuclear facility for the purpose of monitoring whether or not radioactive materials are contained in the exhaust gas. Conventionally, in order to calibrate such a stack radiation monitor, a radiation detection sampler for analyzing a nuclide of a radioactive substance contained in the sampling gas of the stack radiation monitor has been used.

This radiation detection sampler is used only for the analysis of nuclides of radioactive substances contained in gas. Liquid samples and solid samples are collected by other equipment such as a stack radiation monitor, and their nuclides are collected. The analysis is performed using another nuclide analyzer.

[0004]

As described above, since the conventional radiation detection sampler can only analyze the nuclide of gas, the nuclide analysis is performed by using different nuclide analyzers for liquid samples and solid samples other than gas. Each equipment for that is required.

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 velocity of the liquid flowing in the sample chamber is high, Since the radioactive substance does not stay in the sample chamber for a long time, there is a problem that the measurement accuracy is poor.

A first object of the present invention is to provide a sampler for radiation detection which can perform nuclide analysis of liquid samples other than gas and solid samples by the same radiation detector, and has a wide range of equipment utilization. .

A second object of the present invention is to use a fluid-exclusive sampler for radiation detection, which can prolong the residence time of the radioactive substance and improve the measurement accuracy even if the flow velocity of the fluid flowing in the sample chamber is high. To provide.

[0008]

In order to achieve the above object, the present invention constitutes a radiation detecting sampler by the following means. The invention corresponding to claim 1 has a shielding container, a radiation detector provided on the bottom surface side in the shielding container, and a recess into which the radiation detector can be inserted in a portion corresponding to the radiation detector. And a sample chamber in which a flexible pipe for supplying or discharging a sample gas to the inside is connected by penetrating the inside and outside of the shielding container,
This sample chamber is supported so as to be movable up and down, and when performing a nuclide analysis measurement of a liquid or solid sample, the sample chamber is moved to an upper space portion inside the shielding container, and when performing a gas nuclide analysis measurement, A moving mechanism that lowers the sample chamber to a position where the radiation detector is inserted into the recess, and when performing a nuclide analysis of the liquid or solid sample, a sample table is provided near the radiation detector, A liquid or solid sample is placed thereon, and the liquid or solid sample is subjected to nuclide analysis measurement by the radiation detector.

Therefore, in the radiation detecting sampler having such a configuration, when the sample gas is introduced into the sample chamber and the nuclide analysis of the gas is not performed, the same radiation detector is used to analyze the nuclide of the liquid or solid sample. Since the measurement can be performed, the utilization range of the equipment is widened.

According to the second aspect of the invention, a sample chamber is provided in the shielded container and a radiation detector is provided, and the radiation detector emits radioactive substances contained in a fluid continuously flowing in the sample chamber. In a radiation detector sampler for measuring the activity, a hollow fiber membrane filter constituted by a hollow fiber membrane for separating a radioactive substance from the fluid is provided in the sample chamber.

Therefore, in the radiation detecting sampler having such a structure, by providing the hollow fiber membrane filter in the sample chamber, the radioactive substance contained in the fluid is not slowed down without slowing down the flow velocity of the fluid. Only this can be adsorbed on the surface of the hollow fiber membrane and retained in the sample chamber for a long time.

[0012]

BEST MODE FOR CARRYING OUT 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.

In FIG. 1 (a), reference numeral 1 denotes a shield container made of lead, copper or the like installed on a pedestal 2. A cylindrical sample stand 3 is installed in the shield container 1 at substantially the center of its bottom surface. Then, the liquid or solid analysis sample 5 is placed on the support 4 provided in the middle of the sample table 3.

Further, a germanium semiconductor detector (hereinafter referred to as a Ge detector) 6 is provided below the support 4 in the sample table 3, and the Ge detector 6 is provided from the gantry 1 side to the shielded container 1
Is attached to a pipe-shaped guide 7 which is provided by penetrating the bottom portion of the.

A preamplifier 8 for electrically amplifying the radiation detection signal detected by the Ge detector 6 is electrically connected to a cable existing in the guide 7 on the side of the gantry 1 of the guide 7.
Is provided, and a cooling container 9 containing liquid nitrogen is attached to the end of the guide 7.

On the other hand, a sample chamber 10 is provided in the shielding container 1, and the sample chamber 10 is supported by an elevating mechanism 11 mounted vertically on the bottom surface of the shielding container 1 so as to be vertically movable.

The sample chamber 10 is composed of the above-mentioned Ge.
A recess 10a is formed in a portion corresponding to the detector 6, and the Ge detector 6 can be inserted into the recess 10a.
In addition, 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 respectively arranged by penetrating 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 portion 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.

These flexible pipes 12 and 13 are
It is capable of following up and down movements of the sample chamber 10. Next, the operation of the radiation detecting sampler configured as described above will be described.

When analyzing a liquid sample or a solid sample,
As shown in FIG. 1 (a), the sample chamber 10 is moved above the sample table 3 by the elevating mechanism 11, and a liquid sample or a dust sampler (filter paper) collected on the sample table 3 by, for example, a tritum collection device. An analysis sample 5 such as a solid sample collected by an elementary filter (activated carbon adsorption filter) is placed.

In this way, the Ge detector 6 detects the radiation contained in the liquid or solid sample present above it, and the detection signal is amplified by the preamplifier 8 and then
The radionuclide is analyzed by transmitting it to an analyzer (not shown), for example, a multi-channel analyzer.

On the other hand, when performing gas analysis, FIG.
The sample stage 3 and the analysis sample 5 shown in FIG.
1 to move it downward, and then stop at the position where the Ge detector 6 is inserted into the recess 10a formed in the sample chamber 10 as shown in FIG. 1 (b).

In this state, nuclide analysis can be performed by introducing a 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.

As described above, in the first embodiment, the sample chamber 10 which is moved up and down by the elevating mechanism 11 is provided in the shielded container 1, and when the nuclide analysis of the sample gas is performed, the sample is placed above the Ge detector 6. When the gas analysis is not performed by moving the chamber 10, the sample chamber 10 is moved upward to place the sample stage 3 on the Ge detector 6 part, and the liquid or solid sample 5 is placed on the sample stage 3. Since it has been made possible to perform nuclide analysis by installing it, the range of use of the equipment is widened, and equipment for performing nuclide analysis by another nuclide analyzer that corresponds to each sample of liquid and solid other than gas as in the past is provided. It becomes unnecessary.

Although the Ge detector 6 is cooled by the liquid nitrogen housed in the cooling container 9 in the first embodiment, some radiation detectors do not necessarily have the cooling function by the liquid nitrogen. Good.

By the way, in the first embodiment described above, the case where the nuclide analysis of the gas, the liquid and the solid sample is performed by one radiation detection sampler has been described. However, the emission of the radioactive substance contained in the continuously flowing liquid is described. It cannot be applied to those that measure the activity and analyze the nuclide, so a sample chamber dedicated to the liquid is required.

FIG. 2 is a sectional view showing a radiation detecting sampler dedicated to a liquid as a second embodiment of the present invention. In FIG. 2, reference numeral 21 denotes a lead shielding container, and this shielding container 2
The liquid 1 flows into the inside of 1 through an inlet pipe 22 that penetrates through the lower part of one side wall, and circulates through the inside to flow out through an outlet pipe 23 that penetrates the upper part of the other side wall. A sample chamber 24 is provided.

The sample chamber 24 is formed with a recess 24a which bulges inward from the substantial center of the upper surface of the cylindrical body whose both end openings are closed. A radiation detector 25 is inserted into this recess 24a. There is.

Further, the hollow fiber membrane filter 2 which permeates a liquid into the sample chamber 24 and adsorbs a radioactive substance.
6 are provided. The hollow fiber membrane filter 26 is a bundle of thin tubular hollow fiber membranes as shown in FIG. 3, and is configured such that the liquid that has penetrated from the surface to the inside is drained through the hollow portion.

In the radiation detecting sampler having such a structure, the liquid flowing into the sample chamber 24 from the inlet pipe 22 permeates from the surface of the hollow fiber membrane filter 26 to the inside and is discharged to the outside through the outlet pipe 23 through the hollow portion. To be done. At this time, radioactive substances that have not passed through the hollow fiber membrane are adsorbed on the surface of the hollow fiber membrane.

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 on the surface of the hollow fiber membrane for a long time. The measurement accuracy can be improved.

According to the second embodiment described above, by providing the hollow fiber membrane filter 26 in the sample chamber 24, only the radioactive substance contained in the liquid can be provided without slowing down the flow velocity of the liquid flowing continuously. Can be adsorbed on the surface of the hollow fiber membrane and retained in the sample chamber 24 for a long time, and the radiation dose to the radiation detector 25 increases.

This means that when the object to be measured is a liquid having a low radioactivity level, the radioactivity / background radioactivity ratio (S / N ratio) measured by the radiation detector is improved and the measurement accuracy is improved. can do. Although the second embodiment has been described as the measurement target being a liquid, it can be applied to a gas.

[0033]

As described above, according to the radiation detecting sampler of the present invention, it is possible to perform the nuclide analysis of liquid samples other than gas and solid samples by the same radiation detector, thus expanding the range of use of the equipment. can do.

Further, according to the radiation detecting sampler dedicated to the fluid, even if the object to be measured is a fluid having a low level of radioactivity, the hollow fiber membrane filter provided in the sample chamber separates the object to be measured and the fluid. Since the radioactive substance can be separated and retained in the sample chamber, the radioactivity can be accurately measured even if the flow velocity of the fluid continuously flowing in the sample chamber is high.

[Brief description of drawings]

1A and 1B show a first embodiment of a radiation detection sampler according to the present invention, where FIG. 1A is a sectional view when a liquid or solid sample is analyzed, and FIG. 1B is a gas sample analysis. Sectional view of the case.

FIG. 2 is a cross-sectional view showing a second embodiment of a liquid-specific radiation detection sampler according to the present invention.

FIG. 3 is an enlarged perspective view showing a portion A of the hollow fiber membrane filter of FIG.

[Explanation of symbols]

 1 ... Shielding container made of lead, copper, etc. 2 ... Stand 3 ... Sample stand 4 ... Support 5 ... Solid analysis sample 6 ... Ge detector 7 ... Guide 8 ... Preamplifier 9 ... Cooling container 10 ... Sample chamber 11 ... Lifting mechanism 12, 13 ... Flexible piping 21 ... Lead shielding container 22 ... Inlet piping 23 ... Exit piping 24 ... Sample chamber 24a ... Recess 25 ... Radiation detector 26 ... Hollow fiber membrane filter

Claims (2)

[Claims] 1. A shielded container, a radiation detector provided on the bottom side in the shielded container, and a recess into which the radiation detector can be inserted in a portion corresponding to the radiation detector A sample chamber to which a flexible pipe for supplying or discharging a sample gas penetrates the inside and outside of the shielding container and is connected, and supports this sample chamber so that it can be moved up and down, and performs nuclide analysis measurement of a liquid or solid sample. When moving the sample chamber to the upper space of the shield container, when performing the nuclide analysis measurement of the gas, a moving mechanism that lowers the sample chamber to the position where the radiation detector is inserted into the recess When performing a nuclide analysis of the liquid or solid sample, a sample table is provided near the radiation detector, and a liquid or solid sample is placed on the sample table. By the radiation detector is placed a radiation detecting samplers, characterized in that the liquid or solid sample is measured nuclide analysis. 2. A radiation detector for providing a sample chamber in a shielded container and a radiation detector for measuring the radioactivity of a radioactive substance contained in a fluid continuously flowing in the sample chamber by the radiation detector. A sampler for radiation detection, wherein a hollow fiber membrane filter constituted by a hollow fiber membrane for separating radioactive substances from the fluid is provided in the sample chamber.