JP2015081910A - Accumulation device of gas generated by radiation disintegration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an accumulation device of gas generated by radiation disintegration.SOLUTION: An accumulation device of gas generated by radiation disintegration includes: a container 10 which stores a water sample 70 containing tritium; a deaerator 20 connected to the container 10; a sampling syringe 30 connected to the container 10 and having a recovery part 31 being a closed space; and a copper pipe 40 which is connected to a pipeline 61. The sampling syringe 30 is configured such that, when the recovery part 31 has been evacuated by the deaerator 20, helium 3 is recovered into the recovery part 31 and the helium 3 inside the recovery part 31 can be transported under pressure to the inside of the copper pipe 40 according to a compression operation. The copper pipe 40 is configured such that the helium 3 can be encapsulated inside the copper pipe 40 by pressure bonding and closing an opening of its both ends.

Description

  The present invention relates to a concentration device for gas generated by radiation decay.

  In order to develop and effectively use groundwater resources, or to assess the environmental impact of landfill disposal of waste, it is necessary to understand the flow of groundwater in the target area. One method for grasping the flow state is to measure the residence time (groundwater age) of underground water using environmental radioactivity.

  As one of such methods, focusing on the fact that tritium (3H), which is one of the radioisotopes, is β decayed and changed to helium 3 (3He), the groundwater age is estimated by measuring the concentration of 3He. The method of doing is known (for example, refer nonpatent literature 1). Hereinafter, this method is referred to as a tritium-helium method (3H-3He method).

  Since helium 3 is a gas, when collecting a groundwater sample, a water sampling device is used to prevent air contamination. In the water sampling device, the groundwater sample is circulated in the copper pipe so that the atmosphere is not mixed, and the both ends of the copper pipe are crimped in this state, thereby holding the groundwater sample inside the copper pipe. Then, using a mass analyzer for rare gas analysis, the ratio of helium 4 to helium 3 in the copper pipe holding the groundwater sample is measured.

  However, since the concentration of helium 3 obtained from the groundwater sample is very low, it is difficult to accurately measure the concentration of helium 3. Therefore, the present situation is that the ratio of the concentration of helium 4 to helium 3 is measured to estimate the origin of the gas.

  Therefore, in order to determine the amount of helium 3 produced from tritium, it is necessary to concentrate (collect) helium 3.

  Such a problem is present not only when the helium 3 derived from tritium is concentrated, but also when the gas generated by the radiation decay is concentrated.

Yasunori Mahara, Atsuko Ota: "2. Current Status and Distribution of Environmental Tritium 2.5 Dating and Actual Measurement of Groundwater Using Tritium + Helium-3", J. Plasma Fusion Res. Vol.85. No.7 (2009) 434 -436

  An object of this invention is to provide the concentration apparatus of the gas produced | generated by radiation decay.

  A first aspect for achieving the above object includes a container for storing a water sample containing a radioisotope, a deaeration device connected to the container, and a recovery unit that is a closed space connected to the container. And the recovery means has a radiation generated from the radioisotope in the container after the degassing device degass the water sample in the container and evacuates the recovery part. It is in the concentrator of the gas produced | generated by the radiation decay characterized by the destruction gas being collect | recovered in the said collection | recovery part.

  In the first aspect, the water sample in the container is degassed, and the gas of the radiation decay origin that is present from the beginning is removed. Does not contain gas. That is, it is possible to concentrate in the recovery means the gas that originates in the radiation decay that originates only from the radioisotope dissolved in water after deaeration. By measuring this concentrated gas with a mass analyzer, for example, dating of groundwater can be performed more accurately.

  According to a second aspect of the present invention, in the gas concentration device produced by radiation decay described in the first aspect, the recovery means is a variable volume container and a metal tube having the recovery part, The variable volume container degasses the water sample in the container and, after the collection unit is evacuated by the degassing device, sucks and collects the radiation decay gas from the container, and collects this Radiation decay gas is configured to be capable of being pumped into the metal tube, and the metal tube is configured to be capable of sealing the radiation decay gas inside by crimping and closing the openings at both ends. It is in the concentrator of the gas produced | generated by the radiation decay characterized by being characterized.

  In the second aspect, the radiation decay gas once collected in the variable volume container can be concentrated and held in the copper tube, and the copper tube can be directly used in a mass spectrometer.

  According to a third aspect of the present invention, in the gas concentration apparatus produced by the radiation decay described in the first or second aspect, by cooling the inside of a pipe line connecting the container and the recovery means. And a concentrating device for gas generated by radiation decay, comprising a cooling device for liquefying water evaporated from a water sample by deaeration.

  In the third aspect, the water vapor is cooled by the cooling device to become water. That is, since water is not discharged outside the concentration device, the amount of radiation decay gas generated from an arbitrary amount of water sample is determined by measuring the weight of water in the container and water collected by the cooling device. be able to.

  ADVANTAGE OF THE INVENTION According to this invention, the concentration apparatus of the gas produced | generated by radiation decay is provided.

It is a schematic block diagram of the concentration apparatus which concerns on this embodiment. It is the schematic which shows the state of the concentration apparatus at the time of deaerating a water sample. It is the schematic which shows the state which made the concentration apparatus 1 cure. It is the schematic which shows the state of the concentration apparatus at the time of collect | recovering helium 3 to a sampling syringe. It is the schematic which shows the state of the concentration apparatus at the time of concentrating helium 3 to a copper pipe from a sampling syringe. It is sectional drawing of a copper pipe. It is the schematic of an expansion member.

<Embodiment 1>
Hereinafter, a gas concentration device (hereinafter referred to as a concentration device) generated by tritium radiation decay will be described by taking tritium as an example of a radioisotope.

  FIG. 1 is a schematic configuration diagram of a concentration device according to the present embodiment. As shown in the figure, the concentration device 1 includes a container 10 that can store a water sample 70 therein, a deaeration device (vacuum pump) 20, a sampling syringe 30 and a copper tube 40 (metal tube) as recovery means. ) And a cooling device 50.

  A first conduit 61 is connected between the container 10 and the buffer container 51 connected to the cooling device 50, and a second conduit 62 is connected between the buffer container 51 and the sampling syringe 30. Yes. A third pipe 63 is connected between the branch part P1 of the second pipe 62 and the deaerator 20, and a fourth pipe is connected between the branch part P2 of the third pipe 63 and the copper pipe 40. 64 is connected. Further, a fifth pipe 65 is connected between the branch part P3 of the first pipe 61 and the branch part P4 of the second pipe, and the sampling syringe 30 (rear end) is connected from the branch part P5 of the second pipe 62. The sixth pipe line 66 is connected between the (part side).

  The water sample 70 is groundwater collected in an area to be dating, and contains tritium (a radioactive isotope). In addition, the water sample 70 also contains helium 3 that has already been generated as a result of β-decay of tritium.

  The container 10 can store the water sample 70. The container 10 is sealed with a stopper so that the inside is sealed to prevent outside air from entering the inside. The first pipe 61 communicates with the inside of the container 10 through the stopper.

  A bag-like expansion member 71 made of an elastic material such as rubber is disposed inside the container 10. A pipe line 72 that feeds air into the expansion member 71 is connected to the expansion member 71, and one end of the pipe line 72 is exposed to the outside of the container 10. By sending air to the expansion member 71 through the pipe line 72, the expansion member 71 expands and can push up the water level inside the container 10. Thereby, the gas of the space part 73 in the upper part of the container 10 can be pushed out to the 1st pipe line 61 by the raise of a water level.

  The deaeration device 20 is a device that can evacuate the pipe line 60 side, and is connected to the container 10 via a first pipe line 61, a second pipe line 62, and a third pipe line 63. The degassing device 20 can discharge the gas dissolved in the water sample 70 inside the container 10 to the outside of the container 10 (the degassing device 20). That is, although details will be described later, a gas such as helium 3 dissolved in the water sample 70 can be degassed from the water sample 70.

  Moreover, the deaeration device 20 is also connected to the sampling syringe 30 and the copper pipe 40 via the second pipe line 62 and the fourth pipe line 64, and the inside thereof can be evacuated. Yes.

  A sampling syringe 30 which is an example of a variable volume container has a collection unit 31 which is a closed space inside, and the collection unit 31 is connected to the container 10 via a first pipeline 61 and a second pipeline 62. It is connected to the. The recovery unit 31 is configured to recover the helium 3 generated inside the container 10. Moreover, the recovery part 31 is compressed by pressing the piston 32, and the helium 3 can be pumped into the copper pipe 40 via the pipe line 60.

  Furthermore, the rear end side of the sampling syringe 30, that is, the space portion 33 on the piston 32 side is connected to the sixth pipeline 66 and is connected to the deaeration device 20 via the sixth pipeline 66 and the third pipeline 63. Has been. Therefore, not only the recovery unit 31 but also the space 33 on the piston 32 side can be evacuated by the deaeration device 20. With such a configuration, the piston 32 can be moved with a smaller load.

  The copper tube 40 is a copper tubular member having both ends opened. The fourth pipe 64 is inserted from the opening at one end, and the helium 3 pumped from the sampling syringe 30 is supplied to the inside. Moreover, both ends can be crimped to close the openings.

  The figure shows a state in which one opening of the copper pipe 40 is closed and the other opening is inserted into the fourth pipe line 64. In this state, the helium 3 is concentrated inside, and the other opening is closed, so that the helium 3 can be held inside the copper tube 40 in a state of being cut off from the outside air. And this copper pipe 40 can be removed from the 4th pipe line 64, and it can use for the mass analyzer for a noble gas analysis.

  The cooling device 50 is a device that cools a part of the first pipeline 61. Here, a buffer container 51 having an internal space is provided in the middle of the first pipeline 61, and the cooling device 50 is configured to cool the buffer container 51 from the outer surface.

  The cooling device 50 adjusts the temperature of the buffer container 51 so that the helium 3 is maintained in a gas state, while the gas other than the helium 3 such as water (water vapor) becomes a liquid.

  Thereby, helium 3 flows as a gas to the sampling syringe 30, while water vapor or the like can remain in the buffer container 51 as water.

  The first pipe 61 is provided with a valve V <b> 1 between the container 10 and the buffer container 51. In the second pipeline 62, a valve V2 is provided between the buffer container 51 and the branch portion P4. In the third pipeline 63, a valve V3 is provided between the branch part P1 and the branch part P2, and a valve V4 is provided between the branch part P2 and the deaeration device 20. The fifth pipe 65 is provided with a valve V5, and the sixth pipe 66 is provided with a valve V6.

  The operation of recovering helium 3 derived from tritium using the concentration device 1 having the above-described configuration will be described.

  FIG. 2 is a schematic diagram illustrating a state of the concentration device 1 when degassing a water sample. As shown in the figure, first, the water sample 70 in the container 10 is degassed. Specifically, the water sample 70 is deaerated by opening the valves V1 to V4 and V6 and operating the deaerator 20 with the valve V5 closed.

  By this deaeration, helium 3 dissolved in the water sample 70 is discharged as a gas. This helium 3 is discharged out of the system of the concentrator 1 through the pipe line 60. As a result, the dissolved water such as helium 3 is degassed from the water sample 70, but the tritium remains contained.

  Further, during the deaeration, the collection unit 31, the space unit 33, and the copper tube 40 inside the sampling syringe 30 are also decompressed and evacuated.

  FIG. 3 is a schematic view showing a state in which the concentration device 1 is cured. After the helium 3 is discharged from the concentrator 1 by degassing, the valve V1, V5 is closed and left for a predetermined period. At this time, as a countermeasure when a leak occurs in each valve or each pipe, for example, the first pipe 61, the upstream portion (reference numeral 61a in the figure) of the first pipe 61 from the container 10 is closed with a clamp or the like. Is preferred. By closing the first conduit 61 in this way, it is possible to prevent tritium in the atmosphere from being mixed into the container 10 through the leakage of the first conduit 61.

  In this manner, the water sample 70 from which the helium 3 has been removed is left in the container 10 while being blocked from the outside air. Although it depends on the volume of the container 10 and the amount of the water sample 70, the period is about several months to ten and several months.

  If the concentration device 1 is kept cured in such a situation, the tritium in the water sample 70 is destroyed and helium 3 is generated. Since the inside of the container 10 is maintained in a vacuum, the helium 3 is eluted from the water sample 70 and accumulated in the space 73.

  FIG. 4 is a schematic diagram showing a state of the concentration device 1 when helium 3 is collected in the sampling syringe. As shown in the figure, helium 3 newly destroyed from tritium is collected in a sampling syringe 30 in a container 10.

  Specifically, after curing, the valves V1 to V4 and V6 are closed, the valve V5 is opened, and communication is performed from the container 10 to the collection unit 31 of the sampling syringe 30. Then, air is sent from the pipe line 72 to the expansion member 71 to expand the expansion member 71. As a result, the helium 3 in the space 73 is pushed out to the first pipeline 61.

  On the other hand, the recovery unit 31 is expanded by pulling the piston 32 of the sampling syringe 30 and helium 3 is taken into the recovery unit 31. In addition, since the pressure difference is not produced in both space parts because the collection | recovery part 31 and the space part 33 are maintained substantially vacuum, the collection | recovery part 31 expanded by the piston 32 can be maintained with the same size. That is, the piston 32 does not crush the collection part 31 due to the pressure difference between the two space parts.

  The degree to which the expansion member 71 is inflated is such that the pushed-up water enters the first pipe 61 to the fifth pipe 65 to the second pipe 62 and does not reach the collection unit 31 of the sampling syringe 30. It is preferable to do. Thereby, the helium 3 does not remain in the container 10 or each pipeline, and all the helium 3 can be recovered in the recovery part 31.

  Thus, the helium 3 existing in the space 73 of the container 10 is collected in the recovery unit 31 by the expansion of the expansion member 71 and the suction by the sampling syringe 30.

  FIG. 5 is a schematic view showing a state of the concentration device 1 when the helium 3 is concentrated from the sampling syringe to the copper tube, and FIG. 6 is a cross-sectional view of the copper tube. As shown in the figure, the helium 3 collected in the sampling syringe 30 is pumped to the copper tube 40.

  Specifically, by closing the valves V1, V2, V4 to 6 and pressing the piston 32 of the sampling syringe 30 with the valve V3 opened, pressure is applied to the helium 3 in the recovery unit 31, and the second pipe It is pumped to the copper pipe 40 through the path 62 and the fourth pipe 64.

  As shown to Fig.6 (a), the copper pipe 40 is formed in the tubular shape, and the one opening 41 is crimped | bonded and closed. An annular seal member 67 is attached to the distal end portion of the fourth conduit 64 of the concentration device 1. The other opening 42 of the copper pipe 40 is attached to the pipe line 60 via a seal member 67.

  The internal space 43 of the copper tube 40 is evacuated in the above-described deaeration process, and the helium 3 is concentrated by the pressure feeding from the sampling syringe 30 thereafter. That is, the internal space 43 of the copper tube 40 is filled only with helium 3.

  And as shown in FIG.6 (b), the other opening 42 of the copper pipe 40 is crimped | bonded and closed with attaching to the 4th pipe line 64, and the internal space 43 is made into the sealed space. Thereby, it is possible to hold the helium 3 in the internal space 43 in a state of being cut off from the outside air.

  Thereafter, the copper pipe 40 is removed from the fourth pipe 64, and the copper pipe 40 is used in a mass analyzer to measure the concentration of helium 3 in the internal space 43. The age of the groundwater can be estimated by using the tritium-helium method based on the measured concentration of helium 3.

  According to the concentration device 1 described above, the helium 3 once collected by the sampling syringe 30 is compressed and pumped to the copper tube 40, so to speak, the helium 3 in the water sample 70 is contained in the copper tube 40. Is recovered in a concentrated state as a gas.

  Moreover, in the concentration apparatus 1, prior to the collection by the sampling syringe 30, the water sample 70 in the container 10 is degassed and the helium 3 existing from the beginning is removed (or the concentration is negligibly small). . Then, it is cured for a certain period from the state without helium 3, and helium 3 derived from tritium generated during that period can be obtained. That is, the obtained concentration of helium 3 does not include helium 3 existing before curing, and a more accurate concentration of helium 3 derived from tritium can be obtained.

  Furthermore, when degassing, even if the water vapor is about to be discharged out of the system from the container 10 via the first pipe 61, it becomes water by the cooling device 50 and is not discharged outside the concentration device 1. That is, the amount of water contained in the water sample 70 initially supplied into the container 10 does not change in the concentration device 1. Therefore, after the total amount of the initial water sample 70 is X and helium 3 is collected in the copper tube 40, the water sample 70 in the container 10, the water collected by the cooling device 50, If the total of the amount of remaining water measured is Y, the difference between X and Y is the amount of helium 3. Thus, by measuring the amount of water, the amount of helium 3 generated from an arbitrary amount of water sample 70 can be determined.

  In addition, although the sampling syringe 30 and the copper tube 40 were illustrated as a collection | recovery means, if it is the structure which can collect | recover the tritium origin helium 3 supplied from the container 10 in the state interrupted | blocked from external air, the specific structure of a collection | recovery means Is not particularly limited.

<Embodiment 2>
The other form of the expansion member which raises the water level of the water sample 70 in the container 10 is illustrated. FIG. 7 is a schematic view of a container provided with an expansion member. In addition, the same code | symbol is attached | subjected to the same thing as Embodiment 1, and the overlapping description is abbreviate | omitted.

  As shown to Fig.7 (a), you may provide piston 71A as an expansion member in the bottom part side of the container 10 which has space inside. By pushing up the piston 71 </ b> A, the water level of the water sample 70 in the container 10 can be raised, and the gas in the space 73 can be pushed out to the first pipe 61.

  Moreover, as shown in FIG.7 (b), a through-hole may be provided in the bottom part side of the container 10 which has space inside, and the rod-shaped member 71B as an expansion member may be provided in this through-hole via a sealing member. By pushing the rod-like member 71 </ b> B into the container 10, the water level of the water sample 70 can be raised, and the gas in the space 73 can be pushed out to the first pipeline 61.

  The present invention can be used in the industrial field of estimating groundwater age.

DESCRIPTION OF SYMBOLS 1 Concentrator 10 Container 20 Deaerator 30 Sampling syringe 31 Collecting part 32 Piston 40 Copper pipe 50 Cooling device 51 Buffer container 61-66 Pipe line 70 Water sample V1-V6 Valve

Claims (3)

A container for storing a water sample containing a radioisotope;
A deaerator connected to the vessel;
A recovery means having a recovery portion that is a closed space connected to the container;
The recovery means is configured such that after the degassing device degass the water sample in the container and evacuates the recovery part, the radioactive decay gas generated from the radioisotope in the container is in the recovery part. An apparatus for concentrating gas generated by radiation decay, characterized by being configured to be recovered. In the concentration apparatus of the gas produced | generated by the radiation decay of Claim 1,
The collection means is a variable volume container and a metal tube having the collection unit,
The variable volume container degasses the water sample in the container and, after the recovery unit is evacuated by the degassing device, sucks and recovers the radiation decay gas from the container, Configured to be able to pump the radiation decay gas into the metal pipe,
The metal tube is configured such that the radiation decay gas can be sealed inside by crimping and closing the openings at both ends. Concentration of gas generated by radiation decay apparatus. In the concentration apparatus of the gas produced | generated by the radiation decay as described in Claim 1 or Claim 2,
A cooling device for liquefying water evaporated from a water sample by deaeration by cooling the inside of a pipe line connecting the container and the recovery means is provided. Collector.

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