WO2018099429A1 - Experimental device for preparing liquid sample of carbon-14 in radioactive graphite - Google Patents

Abstract

Disclosed is an experimental device (10) for preparing a liquid sample of carbon-14 in radioactive graphite. The experimental device comprises: a pressure-bearing steel cylinder (101), a top end cover (102), a sealing cover (103), two electrodes (104), an ignition wire (105), a support for a sample crucible (106), and an air inflation and discharge valve (107). The experimental device further comprises an adsorption device (110) for tritium-containing steam, wherein the adsorption device (110) in use is arranged inside the pressure-bearing steel cylinder (101), such that an internal space of the pressure-bearing steel cylinder (101) is divided into a first space (115) and a second space (116), and the adsorption device (110) has multiple through holes, the first space (115) and the second space (116) being communicated merely by the adsorption device (110).

Description

Experimental device for preparing carbon-14 liquid sample in radioactive graphite

Cross-reference to related applications

The present application claims priority to Chinese Patent Application No. 20161109388, the entire disclosure of which is incorporated herein in in.

Technical field

The invention relates to the technical field of nuclear industry, in particular to an experimental device for preparing a carbon-14 liquid sample in radioactive graphite.

Background technique

A large amount of graphite material is used in the nuclear industry, and graphite is radioactive after being irradiated by neutrons. In order to process radioactive graphite, it is necessary to establish an analytical method for the radioactivity contained in the graphite, in particular to accurately determine the content of carbon-14 therein. The difficulty in carbon-14 analysis is to prepare carbon-14 in the solid graphite material into a liquid sample for subsequent analysis of carbon-14 using a sophisticated radioactive analytical instrument.

A liquid sample of carbon-14 is currently widely used in the "combustion-absorption method". That is, the graphite containing carbon-14 is ignited in air or oxygen to convert carbon into carbon dioxide, and the absorption liquid absorbs carbon dioxide. Because radioactive graphite also contains another radionuclide, helium. Water vapor containing hydrazine is formed during combustion and is also absorbed by the absorbing liquid, thus causing serious interference with the subsequent measurement of the radioactivity of carbon-14. Therefore, before absorbing liquid, there must be a process of removing water vapor containing hydrazine. For example, Qiu Yongmei et al. reported the preparation of a carbon-14 and the experimental apparatus in the development of a 14C analytical sample preparation system for reactor decommissioned graphite (Atomic Energy Science and Technology, 2010, Vol. 44 (suppl.): 119-123). The method for preparing the carbon-14 sample can be summarized as follows: the graphite is heated and burned under an oxygen atmosphere, the gas is passed through a condenser tube and a silica gel dryer to remove the hydrazine-containing water, and the carbon-14 liquid sample is prepared through the absorbing liquid in the collector. However, the method and apparatus have It has the following disadvantages: (1) complicated equipment, many components, large volume, poor integration; (2) difficult to achieve standardization, most of which are temporary experimental devices, which are not conducive to large-scale production and popularization; (3) control difficulties: When the gas flow rate is too small, it is not conducive to complete combustion of graphite. When the gas flow rate is too large, it is not conducive to the carbon dioxide gas being completely absorbed by the absorption liquid; (4) More radioactive waste: the entire pipeline will be contaminated by carbon-14 and helium; (5) Equipment exists Hazard: Graphite powder has a large specific surface area and is prone to explosion when mixed with oxygen.

In order to partially solve the disadvantages of the above methods, especially for operational safety reasons, there is also a technique for preparing a carbon-14 sample using a high pressure sample burning device (oxygen bomb). A significant difference between this type of technology and previous sample preparation methods is the introduction of a special sample burning device (oxygen bomb). Specifically, the method comprises: burning graphite and oxygen to generate carbon dioxide and hydrazine-containing water vapor in a sealed high-pressure sample burning device; and then opening a valve of the combustion device to guide combustion of carbon dioxide and hydrazine-containing water vapor to be similar to Qiu Yongmei et al. provide water vapor removal and carbon dioxide absorption. However, the method and apparatus still have the following disadvantages: (1) In addition to the sample burning device, it is additionally required to be equipped with a device containing water vapor and carbon dioxide absorption: the equipment is complicated, the integration is poor, and most of them need to temporarily set up water removal and absorb carbon dioxide. The device is not conducive to the promotion of the device. If there is no supporting device, it is impossible to remove the interference of the helium, which is difficult to be used for accurate analysis of C-14; (2) The deflation operation of the sample burning device must be manually controlled and the working intensity is large: the operation of the sample burning device to deflate needs to be based on Internal residual pressure to mediate a bleed valve to keep the deflation rate slow and steady. At present, this operation can only be completed by manual manual control of the spiral bleed valve. The staff needs to continuously mediate for several hours, and the working intensity is very high. (3) The manual deflation operation causes the absorption to be unstable, and the experimental error is large: the sample burning device is released. The gas also requires a slow introduction into the hydrophobic adsorption material and the sodium hydroxide solution, which has a direct effect on the absorption of hydrophobic water and carbon dioxide. In particular, when the passing speed is too fast, the absorption rate is lowered, which affects the measured carbon-14 content. However, the deflation speed is adjusted by manually controlling the spiral bleed valve, the deflation speed fluctuates greatly, the absorption is unstable, the experimental error is large, and the result repeatability is poor.

Therefore, it is a technical problem that needs to be solved to provide a simple and effective apparatus for preparing a liquid sample of carbon-14 in radioactive graphite.

Summary of the invention

The invention provides a simple and effective experimental device for preparing a carbon-14 liquid sample in radioactive graphite.

An experimental device for preparing a carbon-14 liquid sample in radioactive graphite, comprising: a pressurized steel cylinder, a top end cover, a sealing cover, two electrodes, an ignition wire, a sample crucible support, a charge and exhaust valve, wherein The adsorption device of the water vapor is disposed in the pressure-bearing cylinder when the adsorption device is used, thereby dividing the internal space of the pressurized cylinder into the first space and the second space, and the adsorption device has a plurality of through holes, the first space and the second The space is only connected by the adsorption device.

An experimental device for preparing a carbon-14 liquid sample in radioactive graphite, comprising: a sealable reaction vessel and an ignition device; the sealed reaction vessel has a charge and exhaust valve, wherein further comprising an adsorption device containing water vapor, The adsorption device is disposed in the sealed reaction vessel to divide the internal space of the sealed reaction vessel into the first space and the second space, and the adsorption device has a plurality of through holes, and the first space and the second space are only connected by the adsorption device; The first space is used to place a graphite sample and the second space is used to place a carbon dioxide absorbing liquid.

An experimental device comprising: a sealable reaction vessel and an ignition device; the sealed reaction vessel has a charge and exhaust valve, wherein further comprising an adsorption device, the adsorption device is disposed in the sealed reaction vessel, thereby sealing the reaction The inner space of the container is divided into a first space and a second space, and the adsorption device has a plurality of through holes, and the first space and the second space are only connected by the adsorption device; the first space is used for placing the sample to be reacted, and the sample to be reacted after the reaction At least two gases are formed, an adsorption device is used to absorb the gas to be removed in at least two gases, and a second space is used to place a material for absorbing the gas to be collected in the two gases.

Compared with the prior art, the device of the invention integrates the functions of water vapor absorption, carbon dioxide absorption and sample combustion into the pressure-bearing steel cylinder, and the operation is simple.

Other features and advantages of the invention will be set forth in the description which follows, The objectives and other advantages of the invention may be realized and obtained by means of the structure particularly pointed in the appended claims.

The technical solution of the present invention will be further described in detail below through the accompanying drawings and embodiments.

DRAWINGS

The drawings are intended to provide a further understanding of the invention, and are intended to be a In the drawing:

1 is a schematic structural view of an experimental apparatus for preparing a liquid sample of carbon-14 in radioactive graphite according to an embodiment of the present invention.

2 is a flow chart of a method for preparing a liquid sample of carbon-14 in radioactive graphite according to an embodiment of the present invention.

Description of the reference numerals

experimental device	10
Pressure cylinder	101
Top end cap	102
Sealing cap	103
electrode	104
Ignition wire	105
Sample	106
Charge and exhaust valve	107
Beaker	108
Absorption lye	109
Adsorption device	110
First air permeable partition	111
Water vapor absorbing material	112
Second air permeable partition	113
Rubber seal ring	114
First space	115
Second space	116
Magnetic rotor	117

detailed description

The preferred embodiments of the present invention are described below with reference to the accompanying drawings, and it should be understood that The preferred embodiments are merely illustrative of the invention and are not intended to limit the invention.

Referring to FIG. 1 , an experimental apparatus 10 for preparing a liquid sample of carbon-14 in radioactive graphite according to an embodiment of the present invention includes: a pressurized steel cylinder 101 , a top end cover 102 , a sealing cover 103 , two electrodes 104 , an ignition wire 105 , The sample crucible 106, the charge and exhaust valve 107, the beaker 108, the carbon dioxide absorption alkali solution 109, and the helium-containing water vapor adsorption device 110.

The shape and size of the pressurized steel cylinder 101 are not limited and can be set as needed. It can be understood that the pressure-bearing cylinder 101 can also be a container which can be subjected to high pressure by using other metal materials. In the present embodiment, the pressure-bearing cylinder 101 is cylindrical, and its side and bottom are sealed, and the top is open and has a thread that cooperates with the sealing cover 103.

The top end cap 102 is used to form a sealed reaction chamber with the pressurized cylinder 101 that can withstand high pressures. In use, the top end cap 102 is inserted into the top opening of the pressurized cylinder 101.

A sealing cover 103 is used to secure the top end cap 102 to the pressurized cylinder 101. The structure of the sealing cover 103 can be set as needed. In the present embodiment, the sealing cover 103 has a thread that cooperates with the top of the pressurized cylinder 101, and the sealing cover 103 and the top end cover 102 are integrally formed. In use, the sealing cap 103 is fixedly connected to the pressure-bearing cylinder 101 by a screw, thereby pressing the top end cap 102 to ensure that the seal is intact.

The two electrodes 104 are spaced apart from the top end cap 102 and extend from the outside to the inside of the pressurized cylinder 101. The exposed end of the two electrodes 104 is for connection to an external power source, and one end extending to the inside of the pressurized cylinder 101 is used to apply a voltage to achieve ignition. The method of ignition is not limited, and may be an arc discharge or the like. It can be understood that the arrangement positions of the two electrodes 104 are not limited to the top end cover 102, and may be disposed on the pressure-receiving cylinder 101 as long as it extends from the outside to the inside of the pressure-receiving cylinder 101. In the present embodiment, one end of the two electrodes 104 extending to the inside of the pressure-receiving cylinder 101 is electrically connected through an ignition wire 105. In the case where the external power source is energized, a loop is formed by the two electrodes 104 and the ignition wire 105, and the ignition wire 105 is instantaneously ignited and blown by itself. The ignition wire 105 ignites the graphite sample to be tested in the sample crucible 106 to vaporize the sample. It will be appreciated that the electrode 104 and the ignition wire 105 are of an alternative construction and that the invention may also be ignited by other means of ignition or by means of ignition, such as heating the entire reaction vessel.

The sample crucible 106 is disposed in the pressurized cylinder 101 for carrying the graphite sample to be tested. The sample cassette 106 can be disposed on a fixture within the pressurized cylinder 101. In this embodiment, the sample The crucible 106 is fixed to an electrode 104, and the electrode 104 is disposed on the top end cap 102 so that the sample crucible 106 can be taken out of the pressurized cylinder 101 while the top end cap 102 is opened to load the sample. It is to be understood that the sample crucible 106 is not limited to helium, as long as it is a sample carrying device that can withstand high temperatures.

The charge and exhaust valve 107 is used for burning the forward pressurized cylinder 101 with oxygen, and after the combustion and absorption are completed, the exhaust gas in the pressurized cylinder 101 is discharged. The charge and exhaust valve 107 may be disposed on the pressurized cylinder 101 or on the top end cover 102. Preferably, the charge and exhaust valve 107 is disposed on the pressurized cylinder 101 and on the back side of the sample crucible 106 such that the gas flow will blow the sample inside the sample crucible 106 during the aeration process. The charge and exhaust ports of existing devices are typically disposed on the top end cap 102 and facing the sample loaded with the sample. When the unit is filled with oxygen, the intake air stream may blow the sample away. In the present embodiment, the charge and exhaust valve 107 is disposed on the side wall of the pressure-receiving cylinder 101 near the bottom.

The adsorption device 110 is disposed in the pressurized cylinder 101 to divide the internal space of the pressurized cylinder 101 into the first space 115 and the second space 116. The sample cassette 106 is disposed within the first space 115. The adsorption device 110 has a plurality of through holes, and the first space 115 and the second space 116 are communicated only by the adsorption device 110. The hydrazine-containing water vapor and carbon dioxide gas produced by the reaction in the first space 115 may be diffused to the second space 116 by the adsorption device 110, and the hydrazine-containing water vapor may be absorbed by the water vapor absorbing material in the adsorption device 110. The adsorption device 110 includes a first gas permeable partition 111, a second gas permeable partition 113 spaced apart from the first gas permeable partition 111, and a water disposed between the first gas permeable partition 111 and the second gas permeable partition 113. The vapor adsorbing material 112 and a rubber sealing ring 114. Preferably, the edge of the second gas permeable partition 113 is fixed to the rubber seal ring 114 to form a container for placing the water vapor absorbing material 112. In the present embodiment, the adsorption device 110 has a cylindrical or truncated cone shape, and its side surface is fitted to the inner wall of the pressure-bearing steel cylinder 101, and the side wall sealing is realized by the rubber sealing ring 114. A step or a projection (not shown) may be formed on the inner wall of the pressurized cylinder 101 so that the adsorption device 110 can be stuck at the step or the projection. The water vapor absorbing material 112 may be a water absorbing silica gel or the like. A material such as water-absorbing silica gel itself has a large amount of voids, and together with the first gas permeable partition 111 and the second gas permeable partition 113, a passage through which the gas flows freely between the first space 115 and the second space 116 is formed.

The beaker 108 is disposed in the second space 116 inside the pressure-bearing cylinder 101 for containing and absorbing Lye 109. The absorbing alkali 109 is used to absorb carbon dioxide. It will be appreciated that the beaker 108 may also be another container containing the lye 109. In this embodiment, the beaker 108 is disposed at the bottom of the pressure-bearing cylinder 101. The absorbing alkali solution 109 is an aqueous sodium hydroxide solution.

Further, a magnetic rotor 117 may be included in the beaker 108. The magnetic rotor 117 is used to agitate and absorb the alkali liquid 109, thereby accelerating the absorption of carbon dioxide by the absorption alkali liquid 109. It will be appreciated that the magnetic rotor 117 is an optional structure.

It can be understood that the beaker 108, the sample crucible 106, and the carbon dioxide absorbing alkali solution 109 are generally not produced and sold together with other components, and only when the experimental apparatus 10 prepares a liquid sample of carbon-14 in the radioactive graphite, the beaker can be placed. 108. Sample enthalpy 106 and carbon dioxide absorbing lye 109 may not be understood as part of the experimental apparatus 10.

Referring to FIG. 2, an embodiment of the present invention further provides a method for preparing a liquid sample of carbon-14 in radioactive graphite. The method includes the following steps:

S11, providing a sealed reaction vessel having a water vapor-containing adsorption device 110, thereby dividing the internal space of the reaction vessel into a first space 115 and a second space 116; a radioactive graphite sample, a second space 116 is provided with carbon dioxide absorption alkali solution 109;

S12, the sealed reaction vessel is filled with oxygen-containing gas, so that the gas pressure in the reaction vessel reaches 1MPa to 4MPa;

S13, the radioactive graphite sample is burned in an oxygen-containing gas, and the ruthenium-containing water vapor and carbon dioxide gas are formed in the first space 115;

S14, maintaining a period of time, causing the hydrazine-containing water vapor and carbon dioxide gas to diffuse into the second space 116 through the adsorption device 110, the hydrazine-containing water vapor is absorbed by the adsorption device 110, and the carbon dioxide gas is absorbed by the absorption lye 109;

S15, exhausting the sealed reaction vessel.

It can be understood that, in step S14, as the absorption of carbon dioxide by the absorbing alkali 109, the carbon dioxide in the first space 115 and the second space 116 spontaneously diffuses, and after a certain time, the absorbing alkali 109 is applied to all the carbon dioxide in the pressurized cylinder 101. Completely absorbed. In the prior art, the reacted gas is discharged from the pressure-receiving reaction vessel, and the helium-containing steam is adsorbed by the adsorption device and the carbon dioxide gas is absorbed into the alkali solution through the conduit. This method requires manual regulation of traffic to keep enough traffic Small, to avoid the effect of adsorption and removal of mites, carbon dioxide absorption. Moreover, as the gas pressure in the reaction vessel gradually decreases, manual adjustment is required to ensure that the flow rate is stable. In step S14, the absorption alkali liquid 109 may be further stirred to accelerate absorption of carbon dioxide by the absorption alkali liquid 109.

It can be understood that the experimental apparatus 10 and method of the present invention can not only prepare a liquid sample of carbon-14 in radioactive graphite, but can be used to generate two or more different gases after any reaction, and some gases need to be removed, some gases The experiment that needs to be collected.

The following is a specific example of the preparation of a liquid sample of carbon-14 in radioactive graphite using the experimental apparatus 10 of the present invention.

Example 1

In the present embodiment, a method for preparing a liquid sample of carbon-14 in radioactive graphite using the experimental apparatus 10 is as follows:

(1) opening the sealing cover 103 of the experimental device 10, taking out the top end cap 102;

(2) The sample 坩埚106 is placed on the inner support below the top end cover 102, and the sample 坩埚106 is filled with a mass of 0.05 g to 0.2 g of the radioactive graphite sample to be tested, and the ignition wire 105 is connected;

(3) placing a beaker 108 containing a fixed volume of 5.0 ml to 20.0 ml of sodium hydroxide absorbing alkali solution 109 into the bottom of the pressurized steel cylinder 101;

(4) A suitable amount of the silica water vapor absorbing material 112 is placed in the water vapor adsorption device 110 as needed, and then placed inside the pressure-bearing steel cylinder 101 to ensure that the inner wall of the pressure-bearing steel cylinder 101 is sealed by the adsorption device 110;

(5) replacing the top end cap 102, so that the electrode 104, the ignition wire 105, the sample crucible 106, and the sample to be burned are loaded into the pressure-bearing cylinder 101;

(6) sealing the sealing cover 103;

(7) from the charging and exhausting valve 107 is charged with an appropriate amount of high-pressure oxygen, so that the internal pressure of the pressure-bearing cylinder 101 reaches 1MPa to 4MPa;

(8) placing the entire experimental device 10 in the cold water water, and detecting the leak to ensure that the experimental device 10 is sealed;

(9) connecting the electrode 104 to an external power source, igniting the ignition wire 105 and the graphite to be burned by an external power source;

(10) After the sample is burned and cooled, the experimental device 10 is placed on a magnetic stirring device, and the magnetic rotor 117 in the beaker 108 is magnetically stirred to absorb the lye 109 for 5 minutes to 10 minutes to promote the absorption of the lye 109. Absorption of carbon dioxide in a gas;

(11) After the carbon dioxide absorption is completed, the gas in the pressurized cylinder 101 is discharged through the charging and discharging valve 107, and the deflation process can be quickly completed without considering the discharge speed;

(12) The sealing cover 103 is opened, and the beaker 108 is taken out, and the sodium hydroxide in the beaker 108 absorbs the alkali liquid 109 as a subsequent analysis sample.

In order to detect the absorption of carbon dioxide in the gas by the lye 109 in the experimental apparatus 10 and the preparation method of the present invention, in the present embodiment, the gas in the pressurized cylinder 101 is discharged through the charging and exhaust valve 107. The exhausted gas is slowly introduced into the second sodium hydroxide absorbing alkali solution in the other beaker through the conduit, and the second sodium hydroxide absorbing alkali liquid further absorbs the residual carbon dioxide of the gas. As a result, it was found that the carbon dioxide absorbed in the second sodium hydroxide absorption alkali liquid was almost zero. Thus, it can be seen that the absorbing alkali 109 in the experimental apparatus 10 and the preparation method of the present invention can completely absorb the carbon dioxide in the pressurized cylinder 101.

The invention has the following advantages: the device of the invention integrates the functions of water vapor absorption, carbon dioxide absorption and sample combustion, etc., into the pressure-bearing cylinder, and the operation is simple; the method of the invention makes the carbon dioxide in the gas after the reaction diffuse to reach the absorption base The liquid surface avoids the difficulty of manually controlling the deflation process guided by the catheter, which not only reduces the working intensity, greatly improves the efficiency of sample preparation, but also reduces the artificial experimental error and uncertainty, and improves the reliability of the sample preparation process. .

It is apparent that those skilled in the art can make various modifications and variations to the invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and modifications of the invention

Claims (10)

1. An experimental device for preparing a carbon-14 liquid sample in radioactive graphite, comprising:

   Pressure-bearing cylinder, top end cover, sealing cover, two electrodes, ignition wire, sample 坩埚 bracket, charge and exhaust valve;

   Wherein, further comprising an adsorption device containing hydrazine vapor, the adsorption device being disposed in the pressure-bearing steel cylinder when used, thereby dividing the internal space of the pressure-bearing steel cylinder into a first space and a second space, the adsorption The device has a plurality of through holes, and the first space and the second space are communicated only by the adsorption device.
2. The experimental apparatus for preparing a carbon-14 liquid sample in radioactive graphite according to claim 1, wherein the adsorption device comprises a first gas permeable partition, a second gas permeable partition spaced apart from the first gas permeable partition, a water vapor absorbing material disposed between the first gas permeable partition and the second gas permeable partition, and a rubber sealing ring.
3. The experimental apparatus for preparing a carbon-14 liquid sample in radioactive graphite according to claim 2, wherein said second gas permeable separator edge is fixed to said rubber sealing ring to form a container.
4. The experimental apparatus for preparing a carbon-14 liquid sample in radioactive graphite according to claim 2, wherein the inner wall of the pressure-bearing cylinder is cylindrical, and the adsorption device has a cylindrical shape or a truncated cone shape, and the side surface and the bearing body are The inner wall of the cylinder is fitted and the side wall seal is achieved by means of the rubber sealing ring.
5. The experimental apparatus for preparing a carbon-14 liquid sample in radioactive graphite according to claim 2, wherein the water vapor absorbing material is water absorbing silica gel.
6. The experimental apparatus for preparing a carbon-14 liquid sample in radioactive graphite according to claim 1, wherein a step or a projection is formed on an inner wall of the pressure-bearing cylinder to fix the adsorption device to the step or Raised.
7. The experimental apparatus for preparing a carbon-14 liquid sample in radioactive graphite according to claim 1, wherein the two electrodes are disposed on the top end cap, and the sample crucible holder is fixed on one of the electrodes; Two electrodes, an ignition wire and a sample crucible support are disposed in the first space; the charge and exhaust valve is disposed on the pressure-bearing steel cylinder and directly connected to the second space Connected.
8. The experimental apparatus for preparing a carbon-14 liquid sample in radioactive graphite according to claim 1, further comprising a sample crucible and a beaker; the sample crucible being disposed on the sample crucible holder and configured to carry a radioactive graphite sample; The beaker is disposed in the second space and is used for containing carbon dioxide to absorb alkali liquor.
9. An experimental apparatus for preparing a carbon-14 liquid sample in radioactive graphite, comprising: a sealed reaction vessel and an ignition device; the sealed reaction vessel has a charge and exhaust valve, wherein further comprising an adsorption device containing water vapor The adsorption device is disposed in the sealed reaction vessel to divide the internal space of the sealed reaction vessel into a first space and a second space, and the adsorption device has a plurality of through holes, the first The space and the second space are only in communication through the adsorption device; the first space is for placing a graphite sample and the second space is for placing a carbon dioxide absorbing liquid.
10. An experimental apparatus comprising: a sealed reaction vessel and an ignition device; the sealed reaction vessel has a charge and exhaust valve, wherein further comprising an adsorption device, the adsorption device being disposed in the sealed reaction vessel Thereby dividing the inner space of the sealed reaction vessel into a first space and a second space, the adsorption device having a plurality of through holes, the first space and the second space being communicated only by the adsorption device; a first space for placing a sample to be reacted, the sample to be reacted to form at least two gases, the adsorption device for absorbing a gas to be removed in the at least two gases, and the second space for placing An absorbing material for absorbing a gas that needs to be collected among the two gases.

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