A tritium penetration experimental system and method

Abstract

The present invention relates to the technical field of tritium permeation experiment, and in particular to a tritium permeation experiment system and method. The tritium permeation experiment system comprises: a tritium filling unit, a helium filling unit, a permeation unit and a vacuum unit; the permeation unit comprises a cladding tube, a water pipe, a sealing member and a secondary container, the cladding tube is nested in the water pipe, the water pipe is nested in the secondary container, the sealing member comprises an air joint and a water joint, the air joint is arranged at the end of the cladding tube, the water joint is arranged at the end of the water pipe, and one end of the air joint connected to the cladding tube is connected to the water joint; a sealed air chamber is formed in the cladding tube, the sealed air chamber is respectively connected to the tritium filling unit and the helium filling unit, the tritium filling unit and the helium filling unit are connected to the vacuum unit, and the vacuum unit is connected to the secondary container. The present invention solves the problem of leakage and protection of tritium under high pressure.

Description

Technical Field

[0001] The invention relates to the technical field of tritium penetration experiments, and in particular to a tritium penetration experiment system and method. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] The reason why tritium has attracted attention in nuclear power plants is that it mainly exists in the form of tritium coolant. Tritium has a long half-life (12.3 years). If it is left in the plant, it will cause the radioactivity level in the coolant to increase. Once tritium coolant is inhaled, ingested or enters the human body through the skin, it will cause harm to human health. Tritium is a nuclide of key concern in environmental impact assessment and environmental monitoring. GB6249-2011 strictly limits the emission of liquid tritium and gaseous tritium.

[0004] The main sources of tritium in a pressurized water reactor nuclear power plant are fuel fission (ternary fission), burnable poison absorbers, secondary neutron source rod cores, soluble boron and soluble lithium and deuterium in the coolant, etc. The tritium produced by the first three sources can penetrate into the coolant through the cladding tube material. When designing a pressurized water reactor nuclear power plant, it is necessary to give the tritium release share of different cladding tubes. The penetration process of tritium in the cladding tube material is very complicated, so it is necessary to conduct experimental research on the tritium permeation performance of the cladding tube.

[0005] The prior art discloses a tritium permeation test method, in which a T-He mixed gas at normal pressure (slightly higher than 1atm or 124kPa) is filled inside a stainless steel cladding tube, and the tritium seeping out of the outer surface of the cladding tube is purged into the tritium test system with He-Ne gas outside the cladding tube. In a pressurized water reactor nuclear power plant, the coolant temperature is relatively high (about ~300°C) and the operating pressure is about 15MPa. In order to prevent the cladding tube from deforming, a certain pressure of helium needs to be pre-filled inside the tube. However, the above tritium permeation test does not consider the leakage and protection of tritium under high pressure. Summary of the invention

[0006] In view of the shortcomings of the prior art, an object of the embodiments of the present invention is to provide a tritium permeation experimental system to solve the problems of tritium leakage and protection under high pressure.

[0007] In order to achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0008] A tritium permeation experimental system comprises: a tritium filling unit, a helium filling unit, a permeation unit and a vacuum unit; the permeation unit comprises a cladding tube, a water pipe, a sealing member and a secondary container, the cladding tube is nested in the water pipe, the water pipe is nested in the secondary container, the sealing member comprises an air joint and a water joint, the air joint is arranged at the end of the cladding tube, the water joint is arranged at the end of the water pipe, and one end of the air joint connected to the cladding tube is connected to the water joint; a sealed air chamber is formed in the cladding tube, a sealed water chamber is formed between the cladding tube and the water pipe, the sealed air chamber is communicated with the tritium filling unit and the helium filling unit respectively, the tritium filling unit and the helium filling unit are communicated with the vacuum unit, and the vacuum unit is communicated with the secondary container.

[0009] Optionally, the permeation unit further comprises a coil, the sealed gas chamber is connected with the tritium filling unit and the helium filling unit via the coil, the coil is spirally arranged with multiple turns, and the diameter of the coil is smaller than the diameter of the cladding tube.

[0010] Optionally, the air joint is a double-conical tube, the first end of the air joint is an inner conical surface, the second end of the air joint is an outer conical surface, the end of the water joint away from the water pipe is an inner conical surface, the inner conical surface of the first end of the air joint is connected to the coil, and the outer conical surface of the second end of the air joint is connected to the inner conical surface of the water joint.

[0011] Optionally, the seal also includes a first nut and a second nut, a conical joint is provided at the end of the coil, the conical joint has an outer conical surface, the outer conical surface of the conical joint cooperates with the inner conical surface of the first end of the gas joint, the first nut presses the conical joint onto the first end of the gas joint, and the second nut presses the second end of the gas joint onto the water joint.

[0012] Optionally, a heating unit is further included, wherein the secondary container is disposed in the heating unit, and the heating unit is used to heat the permeation unit.

[0013] Optionally, the secondary container includes a secondary container upper cover and a secondary container lower tube, the secondary container upper cover is sealedly connected to the secondary container lower tube, and the vacuum unit is communicated with the secondary container upper cover.

[0014] Optionally, a first pneumatic valve and a first manual valve are provided on the pipeline connecting the tritium filling unit and the permeation unit, a second pneumatic valve and the first manual valve are provided on the pipeline connecting the helium filling unit and the permeation unit, a third pneumatic valve and a second manual valve are provided on the pipeline connecting the vacuum unit and the permeation unit, a fourth pneumatic valve is provided on the pipeline connecting the vacuum unit and the helium filling unit, and a fifth pneumatic valve is provided on the pipeline connecting the vacuum unit and the tritium filling unit.

[0015] The embodiment of the present invention further provides a tritium permeation experimental method of the tritium permeation experimental system as described above, comprising:

[0016] The tritium filling unit inputs negative pressure tritium gas into the permeation unit;

[0017] The helium filling unit inputs positive pressure helium to the permeation unit;

[0018] The permeation cell was heated and cooled to room temperature.

[0019] Optionally, the tritium filling unit inputs negative pressure tritium gas to the permeation unit, including: the vacuum unit evacuates the sealed air chamber to a first preset vacuum degree; heats the tritium filling unit to a first preset temperature, and releases the tritium gas pressure to the first preset pressure; and cools the tritium filling unit to recover the remaining tritium gas in the pipeline;

[0020] The helium filling unit inputs positive pressure helium to the permeation unit, comprising: the vacuum unit evacuates the helium filling unit to a first preset vacuum degree; the helium filling unit fills the pipeline with helium to a second preset pressure; the helium filling unit recovers the remaining helium in the pipeline;

[0021] The permeation unit is heated and cooled to room temperature, including: evacuating the secondary container to a second preset vacuum degree, inserting the heating unit into the lower cylinder of the secondary container, heating the heating unit to a second preset temperature, maintaining the temperature for a first preset time, and then stopping heating.

[0022] Optionally, the first preset vacuum degree is 1×10 -4 Pa, the first preset temperature is 350°C, the first preset pressure is 10Pa~1000Pa, the second preset pressure is 5MPa, the second preset vacuum degree is 10Pa~100Pa, the second preset temperature is 150°C~350°C, and the first preset time is 5h~50h.

[0023] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0024] 1. The tritium permeation experimental system proposed by the present invention realizes double sealing of the sealed air chamber and the sealed water chamber through the sealing element. All the gas in the sealed air chamber and all the water vapor in the sealed water chamber leak into the secondary container, and the secondary container can still be kept in a negative pressure state of less than 1 bar. The vacuum secondary container design effectively ensures the safety of high-pressure tritium operation.

[0025] 2. The use of stainless steel coils effectively reduces the escape of tritium to the outside of the gas chamber when high-pressure helium and negative-pressure tritium are mixed, and at the same time blocks the heat transfer from the heated gas chamber to the first manual valve, thereby improving the high-pressure sealing stability of the valve gasket.

[0026] 3. The present invention uses a tritium filling system to achieve accurate injection of tritium and a helium filling system to achieve accurate input of helium, which improves the accuracy of tritium permeation experimental parameter control and reduces the uncertainty of subsequent experimental data analysis. The tritium permeation experimental system proposed in the present invention simulates the working environment of stainless steel cladding tubes in pressurized water reactor nuclear power plants well, can achieve tritium permeation under preset working conditions and measurement and analysis after permeation, provides experimental samples for the establishment of theoretical research on tritium permeation under high temperature and high pressure of solid samples, and helps to improve the rationality of tritium source design in pressurized water reactor nuclear power plants.

[0027] Advantages of additional aspects of the present invention will be given in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention.

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0030] Figure 1 is a diagram of a tritium permeation experiment system according to an embodiment of the present invention;

[0031] Figure 2 is a schematic diagram of an osmosis unit according to an embodiment of the present invention;

[0032] Figure 3 is a schematic diagram of the connection of the sealing member according to an embodiment of the present invention;

[0033] In the figure: 1. first pneumatic valve; 2. second pneumatic valve; 3. third pneumatic valve; 4. fourth pneumatic valve; 5. fifth pneumatic valve; 6. first manual valve; 7. second manual valve; 8. tritium filling unit; 9. helium filling unit; 10. vacuum unit; 11. lower tube of secondary container; 12. upper cover of secondary container; 13. heating unit; 14. cladding tube; 15. water pipe; 16. sealing element; 17. air joint; 18. water joint; 19. first nut; 20. second nut; 21. cone joint.

[0034] In order to show the positions of various parts, the distances or sizes between them are exaggerated and the schematic diagram is for reference only. DETAILED DESCRIPTION

[0035] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0036] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the present invention explicitly states otherwise, singular forms are also intended to include plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0037] Aiming at the current design requirements of tritium source items in pressurized water reactor nuclear power plants and the shortcomings of existing tritium penetration test technology, a tritium penetration experimental system is proposed through optimization and improvement. It can simulate the operating environment of pressurized water reactor nuclear power plants as much as possible, while improving the protection function of the system. It can solve the current problems such as the assessment of tritium penetration release share in stainless steel cladding tubes, and improve the rationality of the design of tritium source items in pressurized water reactor nuclear power plants.

[0038] like Figure 1 As shown, in one embodiment of the present invention, a tritium permeation experiment system is proposed, including: a tritium filling unit 8, a helium filling unit 9, a permeation unit and a vacuum unit 10, the permeation unit includes a cladding tube 14, a water pipe 15, a sealing member 16 and a secondary container, the cladding tube 14 is nested in the water pipe 15, the water pipe 15 is nested in the secondary container, the sealing member 16 includes an air joint 17 and a water joint 18, the air joint 17 is arranged at the end of the cladding tube 14, the water joint 18 is arranged at the end of the water pipe 15, and one end of the air joint 17 connected to the cladding tube 14 is connected to the water joint 18; a sealed air chamber is formed in the cladding tube 14, a sealed water chamber is formed between the cladding tube 14 and the water pipe 15, the sealed air chamber is communicated with the tritium filling unit 8 and the helium filling unit 9 respectively, the tritium filling unit 8 and the helium filling unit 9 are communicated with the vacuum unit 10, and the vacuum unit 10 is communicated with the secondary container. The specific structures of the tritium filling unit 8, the helium filling unit 9 and the vacuum unit 10 may be based on existing technologies.

[0039] In order to prevent the tritium in the high-pressure helium in the tube from leaking out, a stainless steel seal 16 is designed to achieve sealing, realize the double sealing of the sealed air chamber and the sealed water chamber, and meet the high-temperature water vapor sealing requirements. In order to meet the protection requirements of tritium, a vacuum secondary container is designed outside the stainless steel cladding tube 14. Once a leak occurs, all the gas in the sealed air chamber and all the water vapor in the sealed water chamber leak into the secondary container, and the secondary container can still be kept at a state of less than 1 bar, and both tritium and water can be sealed in the secondary container. The safety of high-pressure tritium operation is effectively guaranteed by the vacuum secondary container design.

[0040] like Figure 1As shown, the pipeline connecting the tritium filling unit 8 and the permeation unit is provided with a first pneumatic valve 1 and a first manual valve 6, the pipeline connecting the helium filling unit 9 and the permeation unit is provided with a second pneumatic valve 2 and the first manual valve 6, the pipeline connecting the vacuum unit 10 and the permeation unit is provided with a third pneumatic valve 3 and a second manual valve 7, the pipeline connecting the vacuum unit 10 and the helium filling unit 9 is provided with a fourth pneumatic valve 4, and the pipeline connecting the vacuum unit 10 and the tritium filling unit 8 is provided with a fifth pneumatic valve 5. The first manual valve 6 is connected to the first pneumatic valve 1 and the second pneumatic valve 2 through a VCR three-way joint, and the second manual valve 7 is connected to the third pneumatic valve 3.

[0041] like Figure 2 As shown, the permeation unit also includes a coil, and the sealed air chamber is connected to the tritium filling unit 8 and the helium filling unit 9 through the coil, and the coil is arranged in a spiral shape with multiple turns, and the diameter of the coil is smaller than the diameter of the cladding tube 14. The function of the coil is to effectively reduce the escape of tritium to the outside of the air chamber when high-pressure helium and negative-pressure tritium are mixed. Another function of the stainless steel coil is to block the heat transfer from the heated air chamber to the first manual valve 6, thereby improving the high-pressure sealing stability of the valve sealing gasket.

[0042] Specifically, the first manual valve 6 is connected to the sealed air chamber via a 2m long stainless steel coil with an outer diameter of 1 / 8 inch. The first manual valve 6 is connected to the stainless steel coil via a 1 / 4VCR joint, and the sealed air chamber is connected to the stainless steel coil via a stainless steel seal 16. When 5MPa high-pressure helium is input from the upper end of the coil, 1kPa tritium in the stainless steel coil is pressed into the air chamber by the high-pressure helium. The coil structure can effectively reduce the escape of tritium to the outside of the air chamber when the high-pressure helium and negative-pressure tritium are mixed. After closing the first manual valve 6, the tritium content in the high-pressure helium in the manual valve external pipeline is at a background state. Figure 3 As shown, the 2-meter-long stainless steel coil is coiled into 14 circles with a length of about 0.1m. The first manual valve 6 is connected to the VCR joint. The highest heating point of the air chamber is at the lower end of the coil. The first manual valve 6 is 0.1m away from the highest heating point, which effectively blocks the heat transfer from the heated air chamber to the first manual valve 6 and improves the high-pressure sealing stability of the valve sealing gasket.

[0043] like Figure 3As shown, the second end of the gas joint 17 is welded to the cladding tube 14, and the water joint 18 is welded to the water pipe 15. The gas joint 17 is a double-conical tube, the first end of the gas joint 17 is an inner conical surface, the second end of the gas joint 17 is an outer conical surface, and the end of the water joint 18 away from the water pipe 15 is an inner conical surface. The inner conical surface of the first end of the gas joint 17 is connected to the coil, and the outer conical surface of the second end of the gas joint 17 is connected to the inner conical surface of the water joint 18. Specifically, the sealing member 16 also includes a first nut 19 and a second nut 20. The end of the coil is provided with a conical joint 21, and the conical joint 21 has an outer conical surface. The outer conical surface of the conical joint 21 cooperates with the inner conical surface of the first end of the gas joint 17. The first nut 19 presses the conical joint 21 against the first end of the gas joint 17, and the second nut 20 presses the second end of the gas joint 17 against the water joint 18. The upper end of the coil is welded to a VCR joint, and the lower end of the coil is welded to a cone joint 21. The cone joint 21 is sealed with the inner cone surface of the first end of the gas joint 17 through a copper gasket, and the outer cone surface of the second end of the joint is sealed with the inner cone surface of the water joint 18 through a copper gasket.

[0044] The tritium permeation experimental system further includes a heating unit 13, the secondary container is arranged in the heating unit 13, and the heating unit 13 is used to heat the permeation unit. The secondary container includes a secondary container upper cover 12 and a secondary container lower tube 11, the secondary container lower tube 11 and the secondary container upper cover 12 can be vacuum sealed by a CF80 knife-edge flange, and the vacuum unit 10 is connected to the secondary container upper cover 12.

[0045] The tritium permeation experimental system of the present invention realizes accurate injection of tritium by using the tritium filling system, realizes accurate input of helium by using the helium filling system, and the secondary container effectively guarantees the tritium safety of the tritium permeation experiment. The experimental system simulates the working conditions of the stainless steel cladding tube 14 of the nuclear power plant well, and provides an experimental sample for the establishment of a theoretical model of high temperature and high pressure tritium permeation of solid samples.

[0046] The present invention also provides a tritium permeation experimental method based on the tritium permeation experimental system, and the tritium permeation experimental method comprises the following steps (all valves are in a closed state before the method is performed):

[0047] (a) The tritium filling unit 8 inputs negative pressure tritium gas to the permeation unit: the first pneumatic valve 1, the fifth pneumatic valve 5 and the first manual valve 6 are opened, and when the molecular pump unit of the vacuum unit 10 evacuates the sealed air chamber to a first preset vacuum degree, the first pneumatic valve 1, the fifth pneumatic valve 5 and the first manual valve 6 are closed; when the tritium metal chemical bed of the tritium filling unit 8 is heated to a first preset temperature, the first pneumatic valve 1 and the first manual valve 6 are opened, and when the tritium gas pressure is released to the first preset pressure, the first manual valve 6 is closed, and after the tritium metal chemical bed of the tritium filling unit 8 is cooled to room temperature, the residual tritium gas in the pipeline is recovered, and the first pneumatic valve 1 is closed and opened;

[0048] (b) The helium filling unit 9 inputs positive pressure helium to the permeation unit: the second pneumatic valve 2 and the fourth pneumatic valve 4 are opened, and when the molecular pump unit of the vacuum unit 10 evacuates the helium filling unit 9 to the first preset vacuum degree, the fourth pneumatic valve 4 is closed; the first manual valve 6 and the second pneumatic valve 2 are opened, and when the high-purity helium cylinder of the helium filling unit 9 fills the pipeline with helium to the second preset pressure through the pressure regulating valve, the first manual valve 6 is closed, and the helium filling unit 9 recovers the remaining helium in the pipeline, and recovers the remaining helium to the negative pressure recovery tank of the vacuum unit 10 for tritium purification, and the recovery pipeline is vacuumed at the same time; the first manual valve 6 is disconnected from the first pneumatic valve 1 and the second pneumatic valve and sealed with a VCR plug. The VCR plug is a 1 / 4 female VCR plug. The first manual valve 6 is a manual valve with a caliber of 1 / 4 inch, and the interface is a male 1 / 4 inch. It needs to be sealed with a 1 / 4 female VCR plug to prevent tritium from leaking from the inside of the valve body.

[0049] (c) The permeation unit is heated and cooled to room temperature: The permeation unit is placed in the lower cylinder 11 of the secondary container, the upper cover 12 of the secondary container is placed above the lower cylinder 11 of the secondary container, and the upper cover 12 of the secondary container and the lower cylinder 11 of the secondary container are sealed by using a CF80 copper pad to form a complete secondary container. The third pneumatic valve 3 and the second manual valve 7 are opened, and when the secondary container is evacuated to the second preset vacuum degree, the third pneumatic valve 3 and the second manual valve 7 are closed. The lower cylinder 11 of the secondary container is inserted into the heating unit 13. When the heating unit 13 is heated to the second preset temperature, it is kept for the first preset time and then the heating is stopped.

[0050] Wherein, the first preset vacuum degree is 1×10 -4 Pa, the first preset temperature is 350°C, the first preset pressure is 10Pa~1000Pa, the second preset pressure is 5MPa, the second preset vacuum degree is 10Pa~100Pa, the second preset temperature is 150°C~350°C, and the first preset time is 5h~50h.

[0051] In order to make the technical solution provided by the embodiment of the present invention clearer, the tritium permeation experimental method provided by the embodiment of the present invention is described by taking an example.

[0052] The tritium permeation method of this embodiment includes the following steps (all valves are closed before the method is performed):

[0053] (a) The tritium filling unit 8 inputs negative pressure tritium gas into the permeation unit: the first pneumatic valve 1, the fifth pneumatic valve 5 and the first manual valve 6 are opened, and the molecular pump unit of the vacuum unit 10 evacuates the sealed gas chamber to 1×10 -4 When the tritium filling unit 8 reaches 350°C, the first pneumatic valve 1 and the first manual valve 6 are opened. When the tritium gas pressure is released to 1000Pa, the first manual valve 6 is closed, the tritium filling unit 8 is cooled to recycle the remaining tritium gas in the pipeline, and the first pneumatic valve 1 is closed and opened.

[0054] (b) The helium filling unit 9 inputs positive pressure helium to the permeation unit: the second pneumatic valve 2 and the fourth pneumatic valve 4 are opened, and the molecular pump unit of the vacuum unit 10 evacuates the helium filling unit 9 to a vacuum of 1×10 -4 When the pressure reaches 5 MPa, the fourth pneumatic valve 4 is closed; when the helium filling unit 9 fills the pipeline with helium to 5 MPa, the first manual valve 6 is opened and closed, and the helium filling unit 9 recovers the remaining helium in the pipeline; the first manual valve 6 is disconnected from the first pneumatic valve 1 and the second pneumatic valve 2 and sealed with a VCR plug.

[0055] (c) The permeation unit is heated and cooled to room temperature: the permeation unit is placed in the lower cylinder 11 of the secondary container, the upper cover 12 of the secondary container is placed above the lower cylinder 11 of the secondary container, and the upper cover 12 of the secondary container and the lower cylinder 11 of the secondary container are sealed with a CF80 copper pad to form a complete secondary container. The third pneumatic valve 3 and the second manual valve 7 are opened, and when the secondary container is evacuated to 80Pa, the third pneumatic valve 3 and the second manual valve 7 are closed. The lower cylinder 11 of the secondary container is inserted into the heating unit 13, and when the heating unit 13 is heated to 350°C, it is kept for 5 hours and then the heating is stopped.

[0056] After the experimental system was heated for 5 hours, the preset vacuum level was still maintained in the secondary container, and no tritium or water vapor leakage occurred.

[0057] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A tritium penetration experimental system, It is characterized in that include: Tritium filling unit, helium filling unit, permeation unit and vacuum unit; The permeation unit comprises a cladding tube, a water pipe, a sealing member and a secondary container, wherein the cladding tube is nested in the water pipe, and the water pipe is nested in the secondary container, and the sealing member comprises an air joint and a water joint, wherein the air joint is arranged at the end of the cladding tube, and the water joint is arranged at the end of the water pipe, and one end of the air joint connected to the cladding tube is connected to the water joint; A sealed air chamber is formed in the cladding tube, and a sealed water chamber is formed between the cladding tube and the water tube. The sealed air chamber is communicated with the tritium filling unit and the helium filling unit respectively. The tritium filling unit and the helium filling unit are communicated with the vacuum unit, and the vacuum unit is communicated with the secondary container. A first pneumatic valve and a first manual valve are arranged on the pipeline connecting the tritium filling unit and the permeation unit, a second pneumatic valve and the first manual valve are arranged on the pipeline connecting the helium filling unit and the permeation unit, a third pneumatic valve and a second manual valve are arranged on the pipeline connecting the vacuum unit and the permeation unit, a fourth pneumatic valve is arranged on the pipeline connecting the vacuum unit and the helium filling unit, and a fifth pneumatic valve is arranged on the pipeline connecting the vacuum unit and the tritium filling unit.

2. The tritium permeation experimental system as claimed in claim 1, It is characterized in that The permeation unit further comprises a coil, the sealed gas chamber is connected with the tritium filling unit and the helium filling unit through the coil, the coil is spirally arranged with multiple turns, and the diameter of the coil is smaller than the diameter of the cladding tube.

3. The tritium permeation experimental system as claimed in claim 2, It is characterized in that The air joint is a double-conical tube, the first end of the air joint is an inner conical surface, the second end of the air joint is an outer conical surface, the end of the water joint away from the water pipe is an inner conical surface, the inner conical surface of the first end of the air joint is connected to the coil, and the outer conical surface of the second end of the air joint is connected to the inner conical surface of the water joint.

4. The tritium permeation experimental system as claimed in claim 3, It is characterized in that The seal also includes a first nut and a second nut. A conical joint is provided at the end of the coil, and the conical joint has an outer conical surface. The outer conical surface of the conical joint cooperates with the inner conical surface of the first end of the gas joint. The first nut presses the conical joint onto the first end of the gas joint, and the second nut presses the second end of the gas joint onto the water joint.

5. The tritium permeation experimental system as claimed in claim 1, It is characterized in that It also includes a heating unit, the secondary container is arranged in the heating unit, and the heating unit is used to heat the permeation unit.

6. The tritium permeation experimental system as claimed in claim 1, It is characterized in that The secondary container comprises a secondary container upper cover and a secondary container lower tube, the secondary container upper cover is sealedly connected with the secondary container lower tube, and the vacuum unit is communicated with the secondary container upper cover.

7. A tritium permeation experimental method of the tritium permeation experimental system according to any one of claims 1 to 6, It is characterized in that include: The tritium filling unit inputs negative pressure tritium gas into the permeation unit; The helium filling unit inputs positive pressure helium to the permeation unit; The permeation cell was heated and cooled to room temperature.

8. The tritium permeation test method as claimed in claim 7, It is characterized in that The tritium filling unit inputs negative pressure tritium gas to the permeation unit, including: the vacuum unit evacuates the sealed air chamber to a first preset vacuum degree; heats the tritium filling unit to a first preset temperature, releases the tritium gas pressure to the first preset pressure; cools the tritium filling unit to recover the remaining tritium gas in the pipeline; The helium filling unit inputs positive pressure helium to the permeation unit, comprising: the vacuum unit evacuates the helium filling unit to a first preset vacuum degree; the helium filling unit fills the pipeline with helium to a second preset pressure; the helium filling unit recovers the remaining helium in the pipeline; The permeation unit is heated and cooled to room temperature, including: evacuating the secondary container to a second preset vacuum degree, inserting the heating unit into the lower cylinder of the secondary container, heating the heating unit to a second preset temperature, maintaining the temperature for a first preset time, and then stopping heating.

9. The tritium permeation test method according to claim 8, It is characterized in that The first preset vacuum degree is 1×10 - 4 Pa, the first preset temperature is 350°C, the first preset pressure is 10Pa~1000Pa, the second preset pressure is 5MPa, the second preset vacuum degree is 10Pa~100Pa, the second preset temperature is 150°C~350°C, and the first preset time is 5h~50h.

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