Leakage self-display all-metal corrugated pipe valve based on beta particle excitation fluorescence

Abstract

The invention discloses a leakage self-display all-metal corrugated pipe valve based on beta particle excitation fluorescence, and relates to the technical field of special valves. The valve comprises a valve body, a valve rod, a corrugated pipe, an executing mechanism and a connecting sleeve arranged on the outer side of the corrugated pipe in a sleeving mode. The core improvement is that a window is arranged on the pipe wall of the connecting sleeve, and the inner surface of the window is coated with a fluorescent material layer which can be excited by beta particles released by tritium decay to emit visible light; meanwhile, the sealing surface of the valve rod head at the lower end of the valve rod is coated with a metal coating. According to the invention, on-line and real-time self-display and rapid positioning of trace leakage are realized by utilizing the radioactivity of tritium; by adopting a full 316L austenitic stainless steel main body structure and a valve rod head gold-plated sealing surface, excellent tritium compatibility, embrittlement resistance and high sealing reliability are ensured; the whole structure is compact, an external complex detection module is not needed, and the device is particularly suitable for gas conveying control in tritium-related systems such as controllable nuclear fusion.

Description

Technical Field

[0001] This invention relates to the field of special valve technology, and in particular to a leak-indicating all-metal bellows valve based on β-particle-excited fluorescence. Background Technology

[0002] In the deuterium-tritium fuel cycle and tritium chemistry and process systems of controlled nuclear fusion devices, the safe and reliable delivery of tritium-containing gas is crucial. Valves, as key control components, must meet extremely stringent dual performance requirements of "tritium compatibility" and "ultra-high sealing performance": First, all materials in contact with tritium-containing media must be able to withstand tritium radioactive irradiation and possess excellent resistance to hydrogen embrittlement and helium embrittlement to inhibit tritium permeation; second, the valve's leakage rate must be better than 1.0 × 10⁻⁶. -9 Pa·m³ / s, to prevent the leakage of radioactive materials.

[0003] Currently, all-metal bellows valves have become the preferred choice for tritium-related systems due to their theoretically achievable zero external leakage characteristic. However, existing bellows valves and related technologies still have the following significant shortcomings in achieving long-term, safe, and reliable operation: 1. Current mainstream leak detection methods have the following drawbacks: 1) Helium mass spectrometry leak detection: As an offline testing method before valves leave the factory or are installed, it cannot perform real-time, online status monitoring of valves during system operation; 2) Environmental tritium monitoring ionization chamber method: This method monitors the overall tritium activity change in a closed space. It can only alarm when the valve leakage is large and causes a significant increase in the environmental tritium concentration. The response time is often more than ten minutes, which cannot achieve early warning of trace leaks and makes it difficult to accurately locate the specific leaking valve. 3) Integrated pressure detection method: This method infers bellows integrity by adding a pressure gauge or pressure transmitter inside the valve cavity. However, this method has low sensitivity, making it difficult to detect minute tritium leaks caused by microcracks. Furthermore, the added cavity and components significantly increase the valve's size and structural complexity, introducing more potential leak points and hindering system miniaturization and integration. 4) Other targeted methods: such as the visual leak detection method using color-changing reagents, which is only applicable to specific chemical media (such as acidic and alkaline fluids) and is completely unsuitable for inert or radioactive tritium environments; while a simple transparent window design can only observe the mechanical state of valve opening and closing and cannot identify micro-cracks in bellows and the resulting leaks.

[0004] 2. In existing valve designs, the selection of key materials in contact with tritium-containing media has the following shortcomings: 1) Organic sealing materials: Some valves still use organic materials such as fluororubber and polytetrafluoroethylene as sealing elements. Under strong tritium irradiation, these materials will undergo irradiation aging and embrittlement, leading to a sharp decline in sealing performance and becoming a weak link in the safe operation of the system; 2) Inappropriate selection and treatment of metal materials: Although metals with certain resistance to hydrogen embrittlement, such as beryllium bronze, are used as valve head materials, their excessive hardness requires a very large actuator driving force to cause plastic deformation of the valve seat to achieve a seal. This results in a cumbersome actuator, and the excessive actuator driving force can cause irreversible plastic deformation of the valve head sealing surface, leading to a reduction in valve service life. Furthermore, such solutions often lack systematic materials science design to address tritium permeation and helium embrittlement issues, and the sealing surface is not reinforced for wear and corrosion resistance. Long-term use carries the risk of accelerated wear and seal failure.

[0005] 3. The existing valve's basic sealing structure has inherent risks: Traditional bellows valves rely primarily on the "bellows-seat" sealing pair for external sealing. The bellows, as a dynamic, lifespan-limited thin-walled element, is susceptible to fatigue failure under repeated stretching and compression cycles. If the bellows ruptures, high-pressure tritium-containing gas will leak directly into the valve stem cavity and to the outside. Existing structures lack secondary seals or isolation barriers in the event of bellows failure.

[0006] 4. The existing valve design is not conducive to system compactness and high reliability requirements: In pursuit of sealing force or integrated detection functions, some existing designs have had to adopt large actuators or add complex detection modules. This not only makes the valves themselves bulky and heavy, but also contradicts the trend of miniaturization and centralization of nuclear facility equipment. Furthermore, the increased number of connection points and components objectively increases the potential leakage points of the system, reducing overall reliability.

[0007] In summary, existing bellows valves face several critical issues that urgently need to be addressed, including real-time online micro-leakage monitoring, long-life tritium-compatible material systems, basic safety sealing structures, and compact integrated designs. Summary of the Invention

[0008] The purpose of this invention is to provide a leak-indicating all-metal bellows valve based on β-particle-excited fluorescence, which can realize online, real-time, and highly sensitive micro-tritium leak self-detection and visual early warning, while possessing excellent tritium compatibility, highly reliable sealing, and compact structure, so as to solve the shortcomings of existing tritium-related valves in terms of leak monitoring, material tolerance, and system integration.

[0009] The technical solution of this invention to solve the above-mentioned technical problems is: a leak-indicating all-metal bellows valve based on β-particle excited fluorescence, comprising a valve body, a valve stem vertically inserted into the top of the valve body, capable of opening / closing the flow channel of the valve body by vertical movement, a bellows sleeved on the lower outer side of the valve stem, capable of extending and retracting with its movement, and a sealed cavity formed between the inner wall of the bellows, the outer wall of the valve stem, and the inner cavity of the valve body, and an actuator for driving its movement is provided on the upper part of the valve stem. It also includes a connecting sleeve fitted on the outside of the bellows. The two ends of the connecting sleeve are connected to the valve body and the actuator, respectively. A viewing window is provided on the wall of the connecting sleeve. The inner surface of the viewing window is coated with a fluorescent material layer that can be excited by β particles released by tritium decay to emit visible light. The lower end of the valve stem is provided with a valve stem head for cutting off the flow channel of the valve body, and the sealing surface of the valve stem head is covered with a metal plating layer.

[0010] As a further improvement of the present invention, the top of the valve body has a sealing end face, and the upper end of the bellows is sealed to the annular protrusion of the outer wall of the valve stem by welding; the lower end of the bellows is fitted to the sealing end face of the valve body by a sealing gasket, and is pressed and fixed to the valve body by a connecting sleeve and a locking nut sleeved on the connecting sleeve.

[0011] As a further improvement of the present invention, the metal base of the valve body, sealing gasket, locking nut, connecting sleeve, valve stem and valve stem head are all made of 316L austenitic stainless steel, and the bellows is made of 316L austenitic stainless steel bellows.

[0012] As a further improvement of the present invention, the metal plating on the sealing surface of the valve stem head is a pre-plated nickel layer and a chemically plated gold layer formed sequentially on its metal substrate.

[0013] As a further improvement of the present invention, the electroless gold plating layer is a cyanide-free sulfite gold plating layer with a thickness of 1.0 μm to 2.5 μm.

[0014] As a further improvement of the present invention, the viewing window is a quartz glass window and is sealed and welded to the connecting sleeve.

[0015] As a further improvement of the present invention, the viewing window is a sapphire window and is sealed and welded to the connecting sleeve.

[0016] As a further improvement of the present invention, the fluorescent material layer is formed by coating and curing a mixture of fluorescent powder and a highly breathable adhesive, wherein the mass ratio of the fluorescent powder to the highly breathable adhesive is 1:3 to 1:5.

[0017] As a further improvement of the present invention, a light-shielding cover with a mesh structure is hinged to the outer wall of the connecting sleeve above the window.

[0018] As a further improvement of the present invention, the actuator includes a cylinder sleeved on the outer side of the upper part of the valve stem, the lower end of the cylinder being fixedly connected to a connecting sleeve, and the inner wall of the connecting sleeve and the outer wall of the valve stem being in sliding sealing fit; the cylinder is provided with a piston that can move vertically, and the piston is fixedly connected to the upper end of the valve stem, and a spring is vertically provided between the upper end face of the piston and the top surface of the cylinder cavity.

[0019] Beneficial effects Compared with the prior art, the advantages of the leak-indicating all-metal bellows valve based on β-particle-excited fluorescence of the present invention are as follows: 1. Achieved online, real-time, highly sensitive self-display and precise location of trace tritium leaks: This invention creatively utilizes the β particles released by tritium decay itself as an excitation source. When even an extremely small rupture or crack occurs in the bellows, causing tritium gas to leak into the inner cavity of the connecting sleeve, the leaking tritium gas activates the fluorescent material layer coated on the viewing window, causing it to emit visible light. This technology does not rely on external detection equipment or large amounts of tritium gas accumulation, has a rapid response, extremely high detection sensitivity, and can directly and quickly locate the leaking valve by observing the light emitted from the specific valve's viewing window. It completely overcomes the shortcomings of traditional helium mass spectrometry leak detection, which requires offline operation, has a slow response to environmental monitoring and cannot locate the leak, and has insufficient sensitivity of integrated pressure detection methods. 2. A comprehensive and superior tritium-compatible material system has been constructed: All components in this valve that come into contact with tritium-containing media are made of 316L austenitic stainless steel as the base material. This material itself has good resistance to hydrogen embrittlement and helium embrittlement, and low tritium permeability. In particular, a special surface treatment process of "pre-plating nickel + cyanide-free gold plating" is adopted for the critical valve stem sealing surface. The excellent ductility of the gold plating layer allows for a tight fit with the sealing surface of the valve body cavity under relatively small actuating force, thereby significantly reducing the size of the actuator; at the same time, the gold plating layer can effectively block tritium from penetrating into the base material. Combined with passivation and annealing processes, the corrosion resistance, wear resistance and long-term stability of the sealing surface are further improved, solving the problems of irradiation aging of organic materials and the need for strong sealing of hard metals. 3. A dual safety guarantee of "structural sealing" and "fluorescent early warning" is formed: By welding the upper end of the bellows to the valve stem and pressing the lower end to the valve body with a gasket, combined with the encapsulation of the connecting sleeve, a relatively independent "monitoring chamber" is formed on the outside of the bellows. Even if the bellows ruptures due to fatigue, the leaked tritium gas is confined within this chamber and immediately displayed by fluorescence. Meanwhile, the connecting sleeve with which the valve stem slides and seals against the external environment still acts as a barrier. Structurally, this significantly reduces the risk of tritium directly leaking into the environment, achieving a higher level of safety design that combines passive response to leakage with active early warning and structural protection. 4. Compact structure, easy system integration, and high reliability: The leakage detection function of this invention is directly integrated into the valve's inherent connecting sleeve viewing window, eliminating the need for additional bulky pressure sensors or complex piping, thus maintaining the simplicity and compactness of the overall valve structure. Simultaneously, thanks to the excellent sealing performance provided by the gold-plated valve stem head, smaller and lighter pneumatic actuators can be used. This integrated and miniaturized design not only reduces potential leakage points within the valve itself but also better meets the requirements for compact and lightweight equipment layout in nuclear facilities, improving the integration and reliability of the entire piping system.

[0020] The invention will become clearer from the following description, taken in conjunction with the accompanying drawings, which are used to explain embodiments of the invention. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a perspective view of the present invention; Figure 2 This is a schematic diagram of the internal structure of the present invention.

[0023] Wherein: 1-valve body; 2-sealing gasket; 3-locking nut; 4-connecting sleeve; 5-valve stem; 6-cylinder; 7-spring; 8-piston; 9-valve stem head; 10-bellows; 11-viewing window. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0025] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; of course, they can also refer to a mechanical connection or an electrical connection; furthermore, they can refer to a direct connection, an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] Embodiments of the present invention will now be described with reference to the accompanying drawings.

[0027] Example: Specific embodiments of the present invention are as follows: Figure 1-2 As shown, a leak-indicating all-metal bellows valve based on β-particle-excited fluorescence is innovatively applied to the physical properties of tritium decay for leak detection, and a complete set of tritium-compatible materials and sealing systems is built around this function.

[0028] This valve is a normally closed pneumatic bellows gate valve, and its main structure is a valve body 1 with inlet and outlet medium flow channels. A valve stem 5 is vertically inserted into the top of the valve body 1, capable of opening / closing the flow channels within the valve body 1 by vertical movement. Specifically, the lower end of the valve stem 5 has a valve stem head 9 for cutting off the flow channels of the valve body 1, and the sealing surface of the valve stem head 9 is covered with a metal plating layer; the upper part of the valve stem 5 has an actuator for driving its movement. Furthermore, a bellows 10, which can extend and retract with the movement of the valve stem 5, is fitted onto the lower outer side of the valve stem 5, and a sealed cavity is formed between the inner wall of the bellows 10, the outer wall of the valve stem 5, and the inner cavity of the valve body 1.

[0029] In addition, the valve also includes a connecting sleeve 4 sleeved on the outside of the bellows 10. The two ends of the connecting sleeve 4 are connected to the valve body 1 and the actuator, respectively, and a viewing window 11 is provided on the wall of the connecting sleeve 4. The inner surface of the viewing window 11 is coated with a fluorescent material layer that can be excited by β particles released by the decay of tritium to emit visible light.

[0030] In this embodiment, the valve body 1 has a sealing end face at its top, and the upper end of the bellows 10 is sealed to the annular protrusion on the outer wall of the valve stem 5 by welding. The lower end of the bellows 10 is fitted to the sealing end face of the valve body 1 by a sealing gasket 2, and is pressed and fixed to the valve body 1 by a connecting sleeve 4 and a locking nut 3 fitted on the outside of the connecting sleeve 4. Meanwhile, the actuator includes a cylinder 6 fitted on the outer side of the upper part of the valve stem 5. The lower end of the cylinder 6 is fixedly connected to the connecting sleeve 4, and the inner wall of the connecting sleeve 4 and the outer wall of the valve stem 5 are in a sliding seal fit. A piston 8 that can move vertically is provided in the cylinder 6, and the piston 8 is fixedly connected to the upper end of the valve stem 5. A spring 7 is vertically provided between the upper end face of the piston 8 and the top surface of the inner cavity of the cylinder 6.

[0031] In this valve, the self-disclosure of leakage based on β-particle-excited fluorescence is achieved through a connecting sleeve 4 fitted onto the outside of the bellows 10. Specifically, the viewing window 11 is fixedly mounted on the connecting sleeve 4 using high-vacuum sealing welding technology—such as vacuum brazing or laser sealing welding. The viewing window 11 is preferably made of quartz glass or sapphire, both of which have excellent light transmittance, radiation resistance, and mechanical strength, ensuring long-term stable signal transmission.

[0032] The core of this valve's ability to achieve "online, real-time, highly sensitive self-display and precise positioning of trace tritium leaks" lies in the functional treatment of the inner surface of the viewing window 11—the side facing the bellows 10. A layer of fluorescent material is coated on this surface. This layer can be prepared by mixing zinc sulfide-based or rare-earth-based fluorescent powder with a highly permeable epoxy resin adhesive or aerogel material at a mass ratio of 1:3 to 1:5 and stirring until homogeneous. The mixture is then coated onto the clean inner surface of the viewing window, controlling the wet film thickness to 50μm-80μm, and subsequently baked at 80℃ for 2-3 hours to cure, forming a robust coating with a dry film thickness of approximately 30μm-50μm.

[0033] Its working principle and effects are explained as follows: When the bellows 10 inside the valve develops micron-sized cracks or even ruptures due to fatigue, corrosion, or other reasons, high-pressure tritium-containing gas leaks into the "low-pressure monitoring chamber" formed by the outer wall of the bellows 10, the inner wall of the connecting sleeve 4, and the viewing window 11. Tritium (³H) atoms continuously release β particles during decay. These β particles have sufficient energy to excite the luminescent centers in the phosphor when they bombard the fluorescent material layer, emitting visible light such as green, blue, or orange. Because this physical process requires extremely low tritium concentration and the excitation is instantaneous, measurements show that when the tritium concentration in the monitoring chamber reaches approximately 1 × 10⁻⁶... 5 Visible fluorescence can be generated at a concentration of Bq / m³, and the response time from tritium gas injection to the observation of the fluorescence signal is less than 30 seconds. Therefore, operators do not need any external instruments; they can determine in real time and intuitively whether the valve has experienced an extremely small leak simply by observing whether the specific viewing window 11 on the valve is lit, and quickly locate the leak point. This perfectly solves the problems of traditional methods, such as inability to operate online, slow response, and inability to locate the leak.

[0034] In this embodiment, to further optimize observation conditions under strong ambient light, an openable and closable light-shielding shield can be hinged to the outer wall of the connecting sleeve 4 above the viewing window 11. This light-shielding shield can be made of radiation-resistant polytetrafluoroethylene or metal mesh. In bright environments, closing this shield can effectively block ambient light interference, ensuring that weak fluorescence signals can be clearly identified.

[0035] Meanwhile, to achieve the goal of "constructing a comprehensive and excellent tritium-compatible material system," the valve underwent systematic material selection and treatment for its key pressure-bearing and sealing components. Specifically, the metal base material of the valve body 1, sealing gasket 2, locking nut 3, connecting sleeve 4, valve stem 5, and valve stem head 9 is all made of 316L austenitic stainless steel. The metal bellows 10 is also made of 316L austenitic stainless steel. This material, with its excellent resistance to hydrogen embrittlement and helium embrittlement and relatively low tritium permeability, forms the basis for the valve's tolerance to tritium irradiation environments.

[0036] In this embodiment, to achieve "excellent tritium compatibility" and a "compact structure," the valve's stem head 9 sealing surface undergoes innovative treatment. Specifically, the sealing surface of the stem head 9 is precision machined to a surface roughness Ra≤0.8μm. Based on this, the following composite coating process is applied to the sealing surface: S1. Pre-plating nickel layer: First, a nickel layer with a thickness of approximately 0.5μm-1μm is chemically plated onto the 316L stainless steel substrate of the valve stem head 9. The plating solution may contain components such as nickel sulfate hexahydrate (250g / L-300g / L), sodium hypophosphite monohydrate (25g / L-30g / L), and citric acid (10g / L-15g / L). The main function of this layer is to enhance the adhesion between the substrate and subsequent plating layers and to alleviate the potential difference between different metals.

[0037] S2. Cyanide-free electroless gold plating: Subsequently, a dense gold layer with a thickness of 1.0 μm to 2.5 μm is deposited using a cyanide-free sulfite gold plating process. The plating solution mainly contains sodium gold sulfite (3 g / L-8 g / L), sodium sulfite (40 g / L-60 g / L), and sodium hypophosphite (10 g / L-20 g / L), with the pH value controlled at 9-11.

[0038] S3. Post-treatment: After gold plating, passivation treatment is performed, such as immersing in 5% chromic acid solution for 5-10 minutes to form a protective film, followed by low-temperature annealing—150℃-200℃ for 1-2 hours under inert atmosphere protection to eliminate internal stress.

[0039] The working principle and effect are explained as follows: Gold possesses excellent ductility, chemical inertness, and low tritium permeability. When the valve is closed, the soft gold layer, upon contacting the hard sealing seat of the valve body 1, undergoes microscopic plastic deformation requiring only a relatively small actuator thrust, thereby achieving an extremely high level of metal-to-metal seal. This allows the actuators required to drive the valve, such as the cylinder 6, piston 8, and spring 7, to be designed to be smaller and lighter, directly achieving a more compact overall valve structure. Simultaneously, the gold layer acts as an ideal barrier, effectively preventing tritium penetration into the substrate material and completely avoiding the problem of organic sealing materials easily aging and failing under tritium irradiation, thus ensuring the valve's long lifespan and high reliability.

[0040] Furthermore, through the aforementioned structural design, this valve also forms a dual safety barrier combining "active early warning" and "passive isolation." Specifically, the lower end of the bellows 10 is mechanically pressed onto the valve body 1 by the sealing gasket 2. The sealing at its upper end is the core of the structure that achieves "dual safety protection": the upper end of the bellows 10 and the annular protrusion on the valve stem 5 are welded together using high-energy beam welding, such as laser welding, to achieve an integrated and permanent sealed connection.

[0041] Its working principle and effect are explained as follows: This fully welded structure completely and permanently isolates the lower part of the valve stem 5 and the tritium-containing fluid inside the valve from the outside environment. Even if the bellows 10 ruptures at its expandable corrugated section, the leaked tritium gas will only be confined to the "monitoring chamber" formed by the outer side of the bellows 10 and the inner side of the connecting sleeve 4, and will immediately trigger the aforementioned fluorescent display for early warning. At the same time, the sliding seal between the valve stem 5 and the external environment still serves as a robust secondary barrier, greatly reducing the probability of tritium-containing media directly leaking into the external environment in terms of physical structure. This achieves a higher level of safety design, moving from simple "leak plugging" to "early warning + isolation".

[0042] It should be noted that the actuator in this embodiment adopts a normally closed pneumatic design. The cylinder 6 is fixed to the connecting sleeve 4. The piston 8 is fixed to the upper end of the valve stem 5 and moves within the cylinder 6. The spring 7 is positioned above the piston 8, providing the default driving force for valve closure. When the valve needs to be opened, compressed gas is introduced into the lower chamber of the piston 8, overcoming the spring force and pushing the valve stem 5 upwards. As mentioned earlier, because the sealing force required for the gold-plated sealing surface of the valve stem head 9 is small, this pneumatic actuator can be significantly miniaturized, further improving the overall integration of the valve and reducing system space occupation and potential leakage points.

[0043] In summary, the embodiments of the present invention have successfully manufactured a novel tritium system-specific valve by integrating β-particle excited fluorescence detection technology, high-performance tritium-compatible coating process, and fully welded bellows sealing structure into an innovative design. This valve combines intelligent leak warning, excellent environmental resistance, intrinsic safety, and compact appearance, providing a reliable solution for the safety control of tritium pipelines in cutting-edge fields such as controlled nuclear fusion.

[0044] The present invention has been described above in conjunction with the preferred embodiments, but the present invention is not limited to the embodiments disclosed above, but should cover various modifications and equivalent combinations made in accordance with the essence of the present invention.

Claims

1. A leak-indicating all-metal bellows valve based on β-particle-excited fluorescence, comprising a valve body (1), wherein a valve stem (5) capable of opening / closing the flow channel of the valve body (1) by vertically moving is vertically inserted into the top of the valve body (1), a bellows (10) capable of extending and retracting with its movement is sleeved on the lower outer side of the valve stem (5), and a sealed cavity is formed between the inner wall of the bellows (10), the outer wall of the valve stem (5), and the inner cavity of the valve body (1), wherein an actuator for driving its movement is provided on the upper part of the valve stem (5), characterized in that, It also includes a connecting sleeve (4) sleeved on the outside of the bellows (10). The two ends of the connecting sleeve (4) are connected to the valve body (1) and the actuator, respectively. A viewing window (11) is provided on the wall of the connecting sleeve (4). The inner surface of the viewing window (11) is coated with a fluorescent material layer that can be excited by β particles released by tritium decay to emit visible light. The lower end of the valve stem (5) is provided with a valve stem head (9) for cutting off the flow channel of the valve body (1), and the sealing surface of the valve stem head (9) is covered with a metal plating layer.

2. The leak-indicating all-metal bellows valve based on β-particle-excited fluorescence according to claim 1, characterized in that, The valve body (1) has a sealing end face at the top. The upper end of the bellows (10) is sealed to the annular protrusion of the outer wall of the valve stem (5) by welding. The lower end of the bellows (10) is in contact with the sealing end face of the valve body (1) through a sealing gasket (2), and is pressed and fixed to the valve body (1) by a connecting sleeve (4) and a locking nut (3) sleeved on the connecting sleeve (4).

3. The leak-indicating all-metal bellows valve based on β-particle-excited fluorescence according to claim 2, characterized in that, The metal base of the valve body (1), sealing gasket (2), locking nut (3), connecting sleeve (4), valve stem (5) and valve stem head (9) is 316L austenitic stainless steel, and the bellows (10) is 316L austenitic stainless steel bellows.

4. The leak-indicating all-metal bellows valve based on β-particle-excited fluorescence according to any one of claims 1-3, characterized in that, The metal plating on the sealing surface of the valve stem head (9) consists of a pre-plated nickel layer and a chemically plated gold layer formed sequentially on its metal substrate.

5. The leak-indicating all-metal bellows valve based on β-particle-excited fluorescence according to claim 4, characterized in that, The electroless gold plating layer is a cyanide-free sulfite gold plating layer with a thickness of 1.0 μm to 2.5 μm.

6. The leak-indicating all-metal bellows valve based on β-particle-excited fluorescence according to claim 1, characterized in that, The viewing window (11) is a quartz glass window and is sealed and welded to the connecting sleeve (4).

7. The leak-indicating all-metal bellows valve based on β-particle-excited fluorescence according to claim 1, characterized in that, The viewing window (11) is a sapphire window and is sealed and welded to the connecting sleeve (4).

8. The leak-indicating all-metal bellows valve based on β-particle-excited fluorescence according to claim 1, characterized in that, The fluorescent material layer is formed by coating and curing a mixture of fluorescent powder and a highly breathable adhesive, wherein the mass ratio of the fluorescent powder to the highly breathable adhesive is 1:3 to 1:

5.

9. The leak-indicating all-metal bellows valve based on β-particle-excited fluorescence according to claim 1, characterized in that, A light-shielding cover with a mesh structure is hinged to the outer wall of the connecting sleeve (4) above the window (11).

10. The leak-indicating all-metal bellows valve based on β-particle-excited fluorescence according to claim 1, characterized in that, The actuator includes a cylinder (6) sleeved on the upper outer side of the valve stem (5). The lower end of the cylinder (6) is fixedly connected to the connecting sleeve (4), and the inner wall of the connecting sleeve (4) and the outer wall of the valve stem (5) are in sliding sealing fit. The cylinder (6) is provided with a piston (8) that can move vertically, and the piston (8) is fixedly connected to the upper end of the valve stem (5). A spring (7) is vertically provided between the upper end face of the piston (8) and the top surface of the inner cavity of the cylinder (6).

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