阅读说明：本技术 放射性同位素生产装置 (Radioisotope production device ) 是由 朱贵凤 邹杨 严睿 康旭忠 陈金根 邹春燕 余呈刚 周波 于 2021-07-09 设计创作，主要内容包括：本发明公开了一种放射性同位素生产装置。该放射性同位素生产装置包括：一端开口的容纳管,用于填装燃料盐；容纳管内设置有第一进气管和第二进气管；所述第一进气管的顶端和所述第二进气管的顶端均位于所述燃料盐的液面以上；所述第一进气管的底端位于所述液面以下；所述第二进气管的底端设置有气体分布器；所述气体分布器的出气口位于所述液面以下且朝向所述液面；所述第一进气管的底端低于所述气体分布器的出气口。该放射性同位素装置具有结构简单、可靠性高、成本低、可更换等优势,利用该装置生产放射性同位素具有流程简单、燃料利用率高、生产效率高、污染小、过程安全、可在线提取等优势。(The invention discloses a radioactive isotope production device. The radioisotope production apparatus includes: the accommodating pipe is opened at one end and is used for filling fuel salt; a first air inlet pipe and a second air inlet pipe are arranged in the accommodating pipe; the top end of the first air inlet pipe and the top end of the second air inlet pipe are both positioned above the liquid level of the fuel salt; the bottom end of the first air inlet pipe is positioned below the liquid level; the bottom end of the second air inlet pipe is provided with an air distributor; the gas outlet of the gas distributor is positioned below the liquid level and faces the liquid level; the bottom end of the first air inlet pipe is lower than the air outlets of the air distributors. The radioactive isotope device has the advantages of simple structure, high reliability, low cost, replaceability and the like, and the radioactive isotope produced by the device has the advantages of simple flow, high fuel utilization rate, high production efficiency, small pollution, safe process, capability of on-line extraction and the like.)

1. A radioisotope production device, comprising: the accommodating pipe is opened at one end and is used for filling fuel salt; a first air inlet pipe and a second air inlet pipe are arranged in the accommodating pipe;

the top end of the first air inlet pipe and the top end of the second air inlet pipe are both positioned above the liquid level of the fuel salt; the bottom end of the first air inlet pipe is positioned below the liquid level; the bottom end of the second air inlet pipe is provided with an air distributor; the gas outlet of the gas distributor is positioned below the liquid level and faces the liquid level; the bottom end of the first air inlet pipe is lower than the air outlets of the air distributors.

2. A radioisotope production device as claimed in claim 1, wherein said fuel salt comprises a nuclear fuel and a base salt; the nuclear fuel is preferably low enriched uranium; the base salt is preferably a fluoride and/or chloride of a metal M, wherein the metal M is one or more of the following elements: li, Be, Na, K, Rb and Zr; the base salt is more preferably NaF and ZrF₄A mixture of (a).

3. A radioisotope production device as claimed in claim 1, wherein said gas distributor is a showerhead, a surface of said showerhead preferably being ellipsoidal.

4. A radioisotope production device as claimed in claim 1, wherein said accommodating tube is provided at an open end thereof with a cover plate, said cover plate being provided with an air outlet tube, a bottom end of said air outlet tube being higher than said liquid level; the air outlet pipe, the first air inlet pipe and the second air inlet pipe all penetrate through the cover plate.

5. A radioisotope production device as claimed in claim 1, wherein a bottom end of said first gas inlet pipe is disposed near a bottom of said accommodating pipe;

and/or the gas outlet of the gas distributor is arranged close to the liquid level.

6. A radioisotope production device as claimed in claim 4, wherein said first inlet conduit, said second inlet conduit and said outlet conduit are provided with valves, any of said valves being switchable between an open state and a closed state.

7. A radioisotope production device as claimed in claim 1, wherein said containment tube is a double-walled sleeve.

8. A radioisotope production device as claimed in claim 7, wherein said double casing has a heating means disposed in a tubular gap; wherein the heating device is preferably an electric heating wire;

and/or a fuel salt monitoring device is arranged in the tube gap of the double-layer sleeve.

9. A radioisotope production device as claimed in claim 1, wherein an insulating layer is provided around the outer periphery of said accommodating tube, wherein said insulating layer is preferably made of a silicon fiber material.

10. A radioisotope production device as claimed in claim 1, wherein said accommodating tube is made of a nickel-based alloy;

and/or the bottom end of the accommodating pipe is arc-shaped.

Technical Field

The present invention relates to a radioisotope production apparatus.

Background

Radioisotopes have found widespread use in the fields of medicine, industry, agriculture, scientific research, resource management and environmental protection, among others.

The production of radioactive isotopes mainly includes an accelerator target activation method, a reactor target fission method, spent fuel extraction, and the like. The target activation method is used for producing neutron-deficient isotopes and has the defects of low yield, low specific activity, high cost and the like. The reactor target fission method is a main way for isotope production, and by irradiating the fission uranium fuel with high flux, a plurality of radioactive isotopes can be produced in large quantity, so that the method has the advantages of high yield, high specific activity, small generator volume and the like, but has the defects of low utilization rate of uranium, more three wastes, nuclear diffusion risk, high cost and the like.

Liquid fuel salts have great advantages in isotope extraction over solid fission targets. It does not need target preparation and shearing and dissolving treatment, and more importantly, related isotopes and their precursor nuclei exist in the forms of gas, volatile and aerosol, such as Xe-133, I-131, Sr-89, Y-90, Mo-99, etc. Because the uranium-enriched fuel is insoluble in fuel salt, the uranium-enriched fuel can be blown into a gas path system in modes of bubbling, spraying and the like, and then is separated from most of high-radioactive substances, so that the isotope extraction process and difficulty are greatly simplified, and the uranium-enriched fuel is basically free from uranium fuel waste and pollution. Therefore, the production of radioisotopes by means of molten salt reactors will have extremely high yields and convenience.

Half a century ago, oak ridge in the united states successfully operated two molten salt stacks, and a large number of radioisotopes, such as Mo-99, Te-132, etc., were examined in the molten salt experimental reactor (MSRE) tail gas system. In the early century, with the rise of development and development of a molten salt reactor, researches on the production of radioisotopes by utilizing the molten salt reactor are increasing. In view of the advancement and technical challenges of molten salt reactors, there is still a significant threshold for building a molten salt reactor compared to other radioisotope production methods. Isotope production in molten salt piles also faces some of its own challenges: (1) the molten salt reactor fuel salt loop has a complex heat exchanger structure and a core component, and radioactive isotope particles are easy to deposit on the surfaces of the metals and graphite, so that less radioactive isotopes are available; (2) the more the content of bubbles carried in the fuel salt loop is, the higher the proportion of the radioactive isotope particles entering the tail gas system is, but the high bubble content can influence the operation safety of the molten salt reactor, so that the proportion of the radioactive isotope particles entering the tail gas system is limited; (3) the bubbling separation system of the molten salt reactor is usually arranged in a pump, the efficiency of the bubbling separation system is related to the running state of the pump, and new requirements are put on the design of the pump.

Disclosure of Invention

The invention aims to solve the technical problems of complex flow, low production efficiency, low fuel utilization rate, more three wastes, nuclear diffusion risk, high cost and the like in the production of radioactive isotopes in the prior art, and provides a radioactive isotope production device. The radioactive isotope device has the advantages of simple structure, high reliability, low cost, replaceability and the like, and the radioactive isotope produced by the device has the advantages of simple process, high fuel utilization rate, high production efficiency, small pollution, safe process, online extraction and the like.

In order to achieve the purpose, the invention adopts the following technical scheme:

the present invention provides a radioisotope production apparatus, comprising: the accommodating pipe is opened at one end and is used for filling fuel salt; a first air inlet pipe and a second air inlet pipe are arranged in the accommodating pipe;

the top end of the first air inlet pipe and the top end of the second air inlet pipe are both positioned above the liquid level of the fuel salt; the bottom end of the first air inlet pipe is positioned below the liquid level; the bottom end of the second air inlet pipe is provided with an air distributor; the gas outlet of the gas distributor is positioned below the liquid level and faces the liquid level; the bottom end of the first air inlet pipe is lower than the air outlets of the air distributors.

When the radioactive isotope production device is used, fuel salt is subjected to fission reaction through neutron irradiation of a reactor to generate isotopes, the isotopes are attached to bubbles blown out of the first air inlet pipe and are brought to the liquid level of the fuel salt, and the isotopes are brought out of the liquid level under the impact of gas blown out of the gas distributor and are collected.

In the present invention, the gas distributor may be a device for uniformly distributing gas, preferably a showerhead, which is conventional in the art.

Wherein, preferably, evenly be provided with a plurality of ventholes on the shower nozzle.

Wherein, preferably, the surface of the nozzle is ellipsoidal. The ellipsoidal nozzle can enable the sprayed gas to be distributed more widely, so that the sweeping efficiency is improved.

In the invention, preferably, the open end of the containing pipe is provided with a cover plate, the cover plate is provided with an air outlet pipe, and the bottom end of the air outlet pipe is higher than the liquid level; the air outlet pipe, the first air inlet pipe and the second air inlet pipe all penetrate through the cover plate.

The first intake pipe and the second intake pipe can be fixed to the setting of apron on the one hand, and on the other hand also can prevent the nuclear diffusion, sets up the outlet duct on the apron, can collect the radioisotope that produces more safely, conveniently.

In the present invention, the fuel salt may be conventional in the art and generally includes nuclear fuel and base salts. Wherein the nuclear fuel is preferably low enriched uranium. The base salt may be a compound having a low melting point and a high boiling point, as is conventional in the art, preferably a fluoride and/or chloride of a metal M, wherein the metal M is one or more of the following elements: li, Be, Na, K, Rb and Zr; more preferably NaF and ZrF₄A mixture of (a).

In the present invention, preferably, the bottom end of the first air inlet pipe is disposed near the bottom of the accommodating pipe.

The gas outlet port of the first gas inlet pipe is close to the bottom of the accommodating pipe, so that the radioactive isotopes generated in the accommodating pipe are completely attached to the bubbles blown out by the first gas inlet pipe and are brought to the liquid level of the fuel salt.

In the present invention, preferably, the gas outlets of the gas distributor are disposed close to the liquid level.

The gas outlet of the gas distributor is arranged close to the liquid level of the fuel salt, the impact force of the gas blown out from the gas outlet on the liquid level is stronger, and more isotope particles can be blown out of the liquid level.

In the invention, the first air inlet pipe, the second air inlet pipe and the air outlet pipe can be provided with valves according to the conventional operation, and any one valve can be switched between an open state and a closed state.

The valve can adjust the aperture of first intake pipe, second intake pipe and outlet duct, opens the valve when needs admit air or give vent to anger, and the valve is closed to the time spent not, can make the radioisotope that generates all discharge and collect by the outlet duct, has improved collection efficiency and has reduced the risk of nuclear diffusion.

In the invention, preferably, the outer periphery of the accommodating pipe is further provided with an insulating layer.

The material of the insulating layer can be conventional in the field, and preferably is a silicon fiber material.

The heat preservation can hold the intraductal temperature of holding in the holding process and keep invariable at the preheating in-process before the holding pipe dress salt.

In the present invention, preferably, the accommodating tube is a double-layer sleeve.

Due to the design of the double-layer sleeve, when the inner-layer pipe leaks, the outer-layer pipe still has the capacity of containing fuel salt, and the release of radioactive substances is avoided.

Wherein, preferably, set up heating device in the tube clearance of double-deck sleeve pipe. Wherein the heating means is preferably an electric heating wire.

Be provided with heating device in the double-deck sheathed tube intertube, can heat the device before the device adorns fuel salt, at the device production radioisotope in-process, if heat transfer is too fast, also can open heating device, heats the fuel salt in the device, makes the intraductal fuel salt of double-deck cover keep liquid, and the temperature is 500 ~ 800 ℃ promptly, and the radioisotope that generates can be carried to the liquid level department of fuel salt by the bubble.

Wherein, preferably, be provided with fuel salt monitoring devices in the tube clearance of double-deck sleeve pipe.

The fuel salt monitoring device can enable the fuel salt to be rapidly monitored when leaking into the tube gap, and the safety of the radioisotope production device is improved.

In the present invention, the material of the accommodating tube may be an alloy, preferably a nickel-based alloy, which is conventional in the art and resistant to the high-temperature corrosion of the fuel salt.

In the invention, when the accommodating pipe is a double-layer sleeve, the inner layer of the double-layer sleeve can be nickel-based alloy, and the outer layer of the double-layer sleeve can be zirconium alloy. The double-layer sleeve is arranged in the reactor, and the cooling medium of the reactor cools the double-layer sleeve, so that the temperature of the fuel salt is kept in a proper range, and the zirconium alloy is more resistant to corrosion of the cooling medium.

In the present invention, preferably, the bottom end of the accommodating tube is arc-shaped.

The radioisotope production device of the present invention, a preferred embodiment, is provided with instructions for assembly and use:

s1: the loading process before stacking comprises the following steps:

(1) and (3) assembling the radioisotope production device in a factory, starting the electric heating wire in the double-layer sleeve, and wrapping the heat-insulating layer on the periphery of the double-layer sleeve to keep the temperature of the double-layer sleeve constant in the salt loading process.

(2) Opening the valve of the first inlet pipe and the valve of the outlet pipe to protect the gas (N)₂Or inert gas) to purge oxygen impurities within the apparatus.

(3) The base salt (e.g. NaF and ZrF) is pressed in from the first inlet pipe by means of gas pressure₄Mixture), the protective gas is discharged from the gas outlet pipe, after being filled with the basic salt, the mixture is kept stand for a period of time, the protective gas is introduced into the gas outlet pipe, and the basic salt is discharged from the first gas inlet pipe rowAnd (6) discharging.

(4) And (4) performing a salt washing operation, and filling the fuel salt until a specified liquid level is reached.

(5) And (6) cooling. And after the salt is filled, continuously injecting protective gas from the top end of the first gas inlet pipe and the top end of the second gas inlet pipe, and discharging the protective gas from the gas outlet pipe. And moving out the heat-insulating layer, closing the heating device, and waiting for the fuel salt to be gradually solidified.

(6) And (6) packaging. As the protective gas is continuously blown into the device, more air holes still exist in the solid molten salt after the fuel salt is condensed. The first air inlet pipe, the second air inlet pipe and the gas distributor are filled with protective gas. And after complete condensation, the valve of the first air inlet pipe, the valve of the second air inlet pipe and the valve of the air outlet pipe are all closed for packaging.

(7) And (5) transporting. And (4) adopting a shock absorption package, and conveying the isotope production device to a specified reactor site through integral transportation.

S2: the in-pile operation and reloading process comprises the following steps:

(1) and (4) performing nuclear heat thawing. The isotope production apparatus is installed in the reactor. The reactor is started, the fuel salt undergoes nuclear fission reaction through high-flux neutron irradiation, a large amount of heat is released, the fuel salt is continuously heated until the fuel salt is melted, the problem of thermal expansion stress caused by melting can be solved because the solid molten salt is of a porous structure, and the problem of local freezing and blocking does not exist because the first air inlet pipe, the second air inlet pipe and the gas distributor are filled with protective gas and do not contain the solid molten salt.

(2) Isotope production. As the fuel salt is subjected to fission reaction, a large amount of fission products are generated, wherein the fission products comprise some difficultly soluble gases and isotope particles, such as Xe-133, Mo-99 and precursor nuclei thereof. These isotope particles are suspended in the fuel salt or attached to the wall surface.

(3) And (4) collecting isotopes. And blowing protective gas into the device through the first gas inlet pipe, wherein the gas forms bubbles in the fuel salt and penetrates through the fuel fission zone. Since gas and isotope particles, etc. tend to adhere to the surface of the bubble, the bubble can bring it to the level of the fuel salt. And (3) blowing protective gas into the device through the second gas inlet pipe, wherein the particle isotopes break the liquid surface under the impact of the protective gas and are discharged out of the device along with gas flow through the gas outlet pipe, and then the isotopes are collected outside the device.

(4) And (4) heat transfer. During operation, the isotope production apparatus achieves temperature control through thermal equilibrium. Nuclear heat is generated in the fuel salt, and the fuel salt flows through bubbling and thermal gradient, so that the internal temperature of the fuel salt is more uniform. The nuclear heat is in turn transferred from the fuel salt to the inner tube of the double-walled sleeve and then to the outer sleeve by thermal radiation, the outer sleeve being cooled by the cooling medium in the reactor.

(5) And (6) replacing the device. After the device has reached its useful life, replacement of the device may be effected within the stack in order to continue to utilize the fuel salt. The specific process is as follows: a new such radioisotope production unit is installed in the reactor, the new unit being cleaned and packaged in the factory. And closing the valves of the air outlet pipes of the new device and the old device, and interconnecting the first air inlet pipe of the new device and the first air inlet pipe of the old device. Said fuel salt in the old unit is forced into the new unit by blowing gas into said second gas inlet pipe of the old unit. The connection is broken and the valve is closed. And taking out the old device from the reactor to finish the replacement of the in-reactor device. The new device can be pre-filled with a certain amount of new fuel salt, and the salt is replaced after the nuclear heat is heated. The new fuel salt can compensate the isotope production reduction problem caused by the burning up of the old fuel, and simultaneously compensate the fuel salt loss problem caused by the fuel salt residue in the salt changing process.

On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.

The positive progress effects of the invention are as follows:

(1) compared with the current solid fuel fission target method, the radioisotope production device provided by the invention has the advantages of high yield, online extraction, simple process flow, lower cost and the like;

(2) compared with isotope production in a molten salt reactor, the invention does not need to rebuild the reactor, can utilize the existing reactor and the radioisotope production device to produce isotopes, and has the advantages of low construction threshold, simple device structure, high reliability and the like;

(3) the simple internal structure reduces the attachment of isotopes on the wall surface, so that the isotope extraction efficiency is higher, in a molten salt reactor experiment, the proportion of isotope particles reaching the liquid level of the fuel salt is approximately 50 percent, the isotope extraction efficiency is close to 100 percent, and the isotope extraction efficiency is greatly improved;

(4) the radioisotope production device is convenient to replace when the service life is reached, the recycling of fuel salt is convenient, the fuel loss is reduced, radioactive waste is reduced, and the pollution is reduced;

(5) the local freezing and blocking problem of each part does not exist in the isotope production; a large amount of bubbles exist in the solid molten salt, so that local stress can be decomposed during melting, and the device is not easy to damage.

Drawings

FIG. 1 is a schematic view of a radioisotope production apparatus;

FIG. 2 is a schematic diagram of a salt charging process of a radioisotope production apparatus;

fig. 3 is a schematic view of the radioisotope production apparatus during operation and refueling.

1-double layer sleeve; 2-fuel salt; 3-cover plate; 4-a first inlet pipe; 41-first intake pipe valve; 5-air outlet pipe; 51-an outlet valve; 6-a second air inlet pipe; 61-second intake pipe valve; 62-a spray head; 7-isotopic particles; 8-bubbles; 9-protective gas space.

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.

The starting materials used in the following examples are all commercially available.

Example 1

S1: the pre-stack loading process is shown in figure 2.

(1) The isotope production apparatus is assembled in a factory. Preheating the device before charging salt. An electric heating wire in the double-layer sleeve 1 is heated, and a heat-insulating layer made of silicon fiber materials is wrapped outside the device, so that the temperature in the salt filling process is constant.

(2) And opening the first air inlet pipe valve 41 and the air outlet pipe valve 51, introducing the protective gas, and purging oxygen impurities in the device.

(3) By basic salts (NaF and ZrF)₄Mixture of (d) inside the cleaning device. The method specifically comprises the following steps: the base salt is pressed in from the first air inlet pipe 4 through air pressure, the protective gas is discharged from the air outlet pipe 5, after the base salt is filled, the mixture is kept stand for a period of time, the protective gas is introduced into the air outlet pipe 5, and the base salt is discharged from the first air inlet pipe 4.

(4) And (4) filling liquid fuel salt 2 until a specified liquid level.

(5) And (6) cooling. After the salt loading is finished, the first gas inlet pipe 4 continuously injects the protective gas, meanwhile, the second gas inlet pipe valve 61 is opened to inject the protective gas, and the gas outlet pipe 5 continuously discharges the protective gas. And moving out the heat-insulating layer, closing the power supply of the electric heating wire, and waiting for the fuel salt 2 to be gradually solidified.

(6) And (6) packaging. Because the protective gas is continuously blown into the device, a plurality of air holes still exist in the liquid fuel salt 2 after the liquid fuel salt is condensed into solid salt. The first air inlet pipe 4 and the second air inlet pipe 6 are filled with protective gas. After complete condensation, the first inlet valve 41, the second inlet valve 61 and the outlet valve 51 are all closed and packaged.

(7) And (5) transporting. And the isotope production device is conveyed to a designated reactor site by integral transportation by adopting a damping package.

S2: the in-stack operation and replacement process is shown in fig. 1 and 3.

(1) And (4) performing nuclear heat thawing. An isotope production device is installed in the reactor. The reactor is started, the fuel salt 2 undergoes nuclear fission reaction through high-flux neutron irradiation, a large amount of heat is released, the fuel salt 2 is continuously heated until being melted, the problem of thermal expansion stress caused by melting can be solved due to the fact that the solid molten salt is of a porous structure, and the problem of local freezing and blocking does not exist due to the fact that no solid fuel exists in the first air inlet pipe 4 and the second air inlet pipe 6.

(2) Isotope production. Due to the fission reaction of the fuel salt 2, a large amount of fission products are generated, which include some insoluble gases and isotope particles 7, such as Xe-133, Mo-99 and their precursor nuclei. These isotope particles 7 are suspended in the fuel salt 2 or attached to the wall surface.

(3) And (4) collecting isotopes. The first inlet valve 41 and the second inlet valve 61 are opened and a shielding gas is bubbled into the apparatus, the gas forming bubbles 8 in the fuel salt 2 through the fuel fission zone. Since the gas and the isotope particles 7 and the like are liable to adhere to the surface of the bubble, the bubble can bring it into the liquid level of the fuel salt 2. Then the liquid level is broken through the gas impact under the liquid level surface, and the isotope particles 7 are brought into the protective gas space 9. The isotope is discharged out of the device along with the airflow from the air outlet pipe 5 in the protective gas space 9, and then the isotope is collected outside the device.

(4) And (4) heat transfer. During operation, the isotope production apparatus achieves temperature control through thermal equilibrium. The nuclear heat is generated in the fuel salt 2, and the fuel salt 2 flows through bubbling and thermal gradient, so that the internal temperature is more uniform. The nuclear heat is in turn transferred from the fuel salt 2 to the inner jacket and then to the outer jacket by thermal radiation, the outer jacket being cooled by the cooling medium in the reactor.

(5) And (6) replacing the device. After the device has reached its useful life, replacement of the nuclear fuel and the device can be carried out in the stack in order to continue to use the fuel salt 2. The specific process is as follows: a new isotope production plant is installed at the same location in the reactor, which is already cleaned and packaged in the factory. The outlet valve 51 of the new and old installation is closed and the first inlet conduit 4 of the new installation is interconnected with the first inlet conduit 4 of the old installation. The fuel salt 2 in the old device is forced into the new device by blowing gas into the second gas inlet pipe 6 of the old device. The connection is broken and the valve is closed. And taking the old device out of the reactor, and finishing the replacement of the in-reactor device and the fuel salt 2. The new device can be pre-filled with a certain amount of new fuel salt 2, and the salt is replaced after the nuclear heat is heated. The new fuel salt 2 can compensate the isotope production reduction problem caused by the burning up of the old fuel, and simultaneously compensate the fuel salt loss problem caused by the fuel salt residue in the salt changing process.

The radioisotope production device in the embodiment 1 has a simple internal structure, effectively reduces the attachment of isotopes on the wall surface, and brings about 100% of isotope particles to the liquid level of the fuel salt by bubbles, while in the molten salt reactor experiment, the proportion of the isotope particles reaching the liquid level of the fuel salt is only about 50%, thereby greatly improving the extraction efficiency of the isotopes.