Reactor base slow positron source, control method and reactor

Abstract

The invention discloses a reactor base slow positron source, a control method and a reactor and belongs to the field of nuclear power. The stack-based slow positron source comprises a slow positron generating assembly, an outer sleeve, a heavy water tank sleeve and a sealing assembly; the outer sleeve is inserted into the heavy water tank through the heavy water tank sleeve, and the tail end of the outer sleeve is immersed in the heavy water; the slow positron generation assembly is arranged at the tail end of the outer sleeve and is sealed in the outer sleeve; the sealing assembly comprises a heavy water sealing mechanism and a light water sealing mechanism, the heavy water sealing mechanism seals a gap between the heavy water tank sleeve and the outer sleeve, and the light water sealing mechanism seals a gap in the pool wall sleeve. The stack-based slow positron source can cool the slow positron generation assembly through heavy water convection, effectively improves the heat dissipation efficiency, and improves the upper limit of the slow positron beam intensity.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of nuclear technology, and particularly relates to a reactor-based slow positron source, a control method and a reactor. BACKGROUND

[0002] The slow positron beam detection technology, especially the detection scheme using slow positron beam as a micro probe, is widely used in non-destructive testing in the field of surface physics and material science, and has the advantages of high detection accuracy, good safety and strong environmental adaptability, and has been widely used in the fields of aerospace, nuclear engineering, semiconductor industry and the like. The beam intensity of the slow positron source based on the reactor is high and stable, and is the slow positron source with the best comprehensive performance. However, the existing reactor-based slow positron sources generally have the problem of insufficient heat dissipation capacity. Since the beam intensity of the slow positron source is closely related to the neutron flux, the higher the neutron flux, the stronger the slow positron beam, but the higher the nuclear heat. The insufficient heat dissipation capacity restricts the development of the reactor-based slow positron source. Therefore, it is of positive significance to provide a reactor-based slow positron source with optimized heat dissipation capacity for improving the beam intensity of the slow positron. SUMMARY

[0003] The present application aims to provide a reactor-based slow positron source to improve the heat dissipation capacity of the reactor-based slow positron source. The present application also provides a reactor-based slow positron source control method and a reactor.

[0004] According to an embodiment of one aspect of the present application, a reactor-based slow positron source is provided, which is arranged in a reactor, wherein the reactor comprises a water pool and a heavy water tank, the heavy water tank is arranged in the water pool, there is a gap between the wall of the heavy water tank and the wall of the water pool, the water pool contains light water, and the heavy water tank contains heavy water; the reactor-based slow positron source comprises:

[0005] a slow positron generating assembly, an outer sleeve, a heavy water tank sleeve and a sealing assembly, wherein

[0006] a pool wall sleeve is arranged on the wall of the water pool,

[0007] the heavy water tank sleeve is connected to the heavy water tank as a whole and communicates with the heavy water tank,

[0008] the outer sleeve extends to the heavy water tank through the pool wall sleeve and the heavy water tank sleeve, so that the end of the outer sleeve is immersed in the heavy water; the slow positron generating assembly is arranged at the end of the outer sleeve and is enclosed in the outer sleeve;

[0009] the sealing assembly comprises a heavy water sealing mechanism and a light water sealing mechanism, the heavy water sealing mechanism seals the gap between the heavy water tank sleeve and the outer sleeve, and the light water sealing mechanism seals the gap in the pool wall sleeve.

[0010] The heavy water tank sleeve is arranged in an open structure, and the outer sleeve end is directly immersed in the heavy water, so that the heavy water directly cools the slow positron generating assembly in circulation, effectively improves the cooling efficiency compared with the air cooling structure, allows the slow positron generating assembly to generate higher beam intensity, and significantly reduces the risk of material melting. At the same time, the distance between the positron generating assembly and the reactor core can be adjusted by controlling the length of the outer sleeve, thereby controlling the slow positron beam intensity. The heavy water in the heavy water tank is isolated and closed by the heavy water sealing mechanism to prevent heavy water leakage and mixing with light water.

[0011] Further, in some embodiments, the sealing assembly includes a bellows, which is sleeved outside the outer sleeve and connected to the heavy water tank sleeve and the pool wall sleeve respectively.

[0012] Further, in some embodiments, the connection end of the bellows and the heavy water tank sleeve is respectively provided with a flange, and the flanges of the bellows and the heavy water tank sleeve are butted to form the heavy water sealing mechanism.

[0013] Further, in some embodiments, the end flange is arranged at one end of the bellows extending to the pool wall sleeve, and a flange is arranged at one end of the pool wall sleeve outside the pool wall and connected to the end flange to form the light water sealing mechanism.

[0014] Further, in some embodiments, a helium gas inlet is arranged on the bellows to allow helium gas to be filled into the bellows.

[0015] The helium gas filled in the bellows can improve the cooling effect.

[0016] Further, in some embodiments, the slow positron generating assembly includes an (n, γ) converter, a (γ, e+) converter and a moderator arranged in sequence along the axis of the outer sleeve, and the (n, γ) converter is arranged on the wall body at the end of the outer sleeve.

[0017] The (n, γ) converter is arranged on the wall body at the end of the outer sleeve, so that the heavy water in the heavy water tank can directly take away the heat generated by the (n, γ) converter, effectively improving the heat dissipation efficiency.

[0018] Further, in some embodiments, the slow positron generating assembly further includes a vacuum cylinder and a beam tube, the vacuum cylinder is arranged in the outer sleeve, the beam tube is arranged in the vacuum cylinder, the (γ, e+) converter and the moderator are arranged in the vacuum cylinder, the moderator is fixedly arranged at the end of the beam tube, and the (γ, e+) converter is arranged in connection with the moderator.

[0019] Further, in some embodiments, a sealing mechanism is provided between the vacuum cylinder and the pool wall sleeve.

[0020] The sealing mechanism between the vacuum cylinder and the pool wall sleeve can further improve the sealing performance and reduce the risk of leakage of heavy water and light water.

[0021] Further, in some embodiments, the outer sleeve is arranged in an inclined manner, wherein the end of the outer sleeve inserted into the heavy water tank is the lower end, and the opening height of the pool wall sleeve outside the pool is higher than the top of the heavy water tank.

[0022] The inclined arrangement of the outer sleeve can ensure that even if leakage occurs, the light water will not fall below the safe liquid level, ensuring the safety of the reactor.

[0023] According to another aspect of the embodiments of the present application, a method for controlling the slow positron beam intensity of a reactor-based slow positron source is provided, which is used to control the slow positron beam intensity of the reactor-based slow positron source provided in any of the preceding embodiments, and comprises the following steps:

[0024] Adjusting the depth of the outer sleeve inserted into the heavy water tank to adjust the distance between the slow positron generating assembly and the reactor core.

[0025] According to another aspect of the embodiments of the present application, a reactor is provided, which comprises a reactor-based slow positron source configured as the reactor-based slow positron source provided in any of the preceding embodiments.

[0026] Further, in some embodiments, the reactor comprises a plurality of the reactor-based slow positron sources;

[0027] The outer sleeve of the reactor-based slow positron source is arranged in an inclined manner, wherein the end of the outer sleeve inserted into the heavy water tank is the lower end;

[0028] The outer sleeves of the plurality of reactor-based slow positron sources have different inclination angles. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 A schematic diagram of the working principle of a reactor-based slow positron source;

[0030] Figure 2 A schematic diagram of the structure of a reactor-based slow positron source in an embodiment;

[0031] Figure 3 A schematic diagram of the structure of a reactor-based slow positron source in a comparative example.

[0032] Meaning of reference signs:

[0033] 1 -(n,γ) converter; 2 -(γ, e+) converter; 3 - moderator; 4 - beam tube; 5 - vacuum cylinder; 6 - coil; 7 - outer sleeve; 8 - heavy water tank sleeve; 9 - bellows; 10 - cell wall sleeve; 11 - heavy water tank sleeve flange; 12 - bellows front end flange; 13 - bellows step flange; 14 - outer sleeve flange; 15 - cell wall sleeve flange; 16 - bellows rear end flange; 17 - vacuum cylinder sealing flange; 18 - vacuum cylinder helium inlet; 19 - vacuum cylinder helium outlet; 20 - bellows helium inlet; 21 - bellows helium outlet; 22 - heavy water tank; 23 - water cell; 24 - water cell wall.

[0034] The above-described drawings are intended to provide a detailed description of the present application, so that those skilled in the art can understand the technical concept of the present application, and are not intended to limit the present application. In order to express concisely, the above-described drawings only schematically draw the structures related to the technical features of the present application, and do not strictly draw the complete structures and all details according to the actual proportions. DETAILED DESCRIPTION

[0035] The present application will be further described in detail through specific examples combined with the drawings.

[0036] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment. The appearances of the phrase that the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive or alternative implementations. Those skilled in the art will appreciate from the present description that various embodiments of the present application can comprise combinations of some or all of the described features, structures, or characteristics, without limitation.

[0037] In the description of the present application, unless otherwise explicitly specified and limited, the technical terms "mount", "connect", "connection" and the like should be understood in a broad sense, for example, can be movable connection, or fixed connection or integrated. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0038] In the description of the present application, the terms indicating the orientation or position relationship such as "upper", "lower", "left", "right", "transverse", "longitudinal", "height", "length", "width" and the like are intended to accurately describe the embodiments and simplify the description, and are not intended to limit the parts or structures involved to have a specific orientation, be installed or operated in a specific orientation, and cannot be understood as limiting the embodiments herein.

[0039] In the description of the present application, the terms "first", "second" and the like are only used to distinguish different objects, and cannot be understood as indicating relative importance or limiting the number, specific order or primary and secondary relationship of the described technical features. In the description of the present application, the meaning of "a plurality of" is at least two.

[0040] Positron is the anti-matter particle of electron, which will annihilate with the electron in the material after incident. With the annihilation property of positron, the micro-defect and micro-structure in the material can be accurately characterized, and the element type and distribution information in the defect and the defect structure characteristics can be obtained. At present, as a micro-probe for detecting the surface of the material, positron beam has been widely used in the fields of surface physics, material science, aerospace industry, nuclear industry and semiconductor industry. In practical application, the penetration depth of high-energy positron (hundreds of keV to MeV) is difficult to control, and it is impossible to realize layer-by-layer analysis of the surface, interface or thin film structure of the material, so the slow positron detection technology with energy in the order of eV-keV has been more widely applied.

[0041] The slow positron source mainly includes three types of radioisotope-based, accelerator-based and reactor-based, which rely on high-energy gamma ray targeting of radioisotopes, high-energy electron targeting of electron accelerators and neutron targeting of reactors to generate slow positrons. At present, with the development of surface physics and thin film materials, the demand for high-precision characterization of the microstructure of the material surface in the field of polymer materials or semiconductor thin film materials in the form of film is higher and higher for the beam intensity and energy monochromaticity of the slow positron beam. Among the three types of slow positron sources, the positron beam intensity of the reactor-based slow positron source (reactor-based slow positron source) can reach 10 8 -10 9 e+ / s, which is much higher than that of the radioisotope source, and the continuity and stability of the beam output are significantly better than those of the accelerator source, so it has the most promising application prospect.

[0042] The basic principle of the reactor-based slow positron source is shown in Figure 1 The neutrons generated by the reactor core bombard the (n, γ) converter to generate γ-ray photons, and the γ-ray photons bombard the (γ, e+) converter to generate positrons. The positrons then enter the moderator, lose energy through inelastic collisions, and then are guided out to form a slow positron beam. In the process of generating the reactor-based slow positron, neutrons and γ photons will deposit energy on the converter, especially on the (n, γ) converter. The process of absorbing neutrons and releasing γ photons will release a large amount of energy, which will be deposited on the (n, γ) converter and account for the main part of the energy deposition of the generating device. Therefore, appropriate heat dissipation measures need to be prepared for the (n, γ) converter in the design to ensure that the temperature of the generating device does not exceed the critical value and safety limit of the material.

[0043] At present, the conventional structure of the reactor-based slow positron source is as shown in Figure 3As shown in the figure, the reactor is provided with a channel accommodating the slow positron source, specifically, a heavy water tank 22 is accommodated in a pool 23 of the reactor, light water is injected into the pool 23 and the heavy water tank 22 is immersed in the light water, and the reactor core is accommodated in the heavy water tank 22, and horizontal channels are formed in the wall of the pool 23 and the wall of the heavy water tank 22 to accommodate the slow positron source device. The channel of the heavy water tank 22 is provided with a heavy water tank sleeve 8 with a closed end, the channel of the pool wall 24 is provided with a pool wall sleeve 10, and a bellows 9 is connected between the heavy water tank sleeve 8 and the pool wall sleeve 10; the heavy water tank sleeve flange 11 at the end of the heavy water tank sleeve 8 is connected to the front end flange 12 of the bellows, and the rear end flange 16 of the bellows is connected to the pool wall sleeve flange 15, forming a sealed structure to block the heavy water and the light water outside the channel. The outer sleeve 7 and the vacuum cylinder 5 arranged in the outer sleeve 7 pass through the pool wall sleeve 10 and the bellows 9 and extend to the end of the heavy water tank sleeve 8, and the slow positron generating assembly is arranged in the vacuum cylinder 5 and specifically includes a beam tube 4 extending out of the reactor core, and an (n, γ) converter 1, a (γ, e+) converter 2 and a moderator 3 arranged in series along the axial direction at the end of the beam tube 4, wherein the (n, γ) converter 1 is arranged at the end of the series structure, and the slow positron beam is guided out of the reactor by a coil 6 after being emitted out of the reactor core along the beam tube 4. During the operation of the slow positron source, neutrons, γ photons and the like mainly generate nuclear heat on the converters and the moderator 3. The end of the vacuum cylinder 5 is provided with a vacuum cylinder sealing flange 17, the vacuum cylinder sealing flange 17 is connected to the rear end flange 16 of the bellows to form a sealed structure, and the vacuum cylinder sealing flange 17 is provided with a vacuum cylinder helium gas inlet 18 and a vacuum cylinder helium gas outlet 19, so that a helium gas flow is formed in the chamber between the vacuum cylinder 5 and the outer sleeve 7, and the heat generated by the converters and the moderator 3 is transferred to the vacuum cylinder through heat radiation and is dissipated through the convection of the flowing helium gas.

[0044] The beam intensity of the reactor-based slow positron source depends on the neutron flux in the reactor core, and the increase of the neutron flux will bring higher nuclear heat, and when it is necessary to further increase the slow positron beam intensity, the helium gas flow cooling will be insufficient to fully remove the nuclear heat, and when the excessive heat is deposited, the temperature of the material will exceed the critical value, causing equipment failure or even material melting. Therefore, the heat dissipation capacity is restricting the application of the reactor-based slow positron source.

[0045] However, since the main body of the reactor-based slow positron source is arranged in the reactor, the space is limited, and the additional cooling device will significantly increase the system complexity and development cost, and the introduction of the new cooling device into the reactor core will also cause the reliability of the system to decrease.

[0046] In order to solve the above problems, an embodiment of one aspect of the present application provides a reactor-based slow positron source with better cooling performance. The structure of the reactor-based slow positron source is as shown in the figure. Figure 2

[0047] ​The slow positron source comprises a slow positron generating assembly, an outer sleeve 7, a heavy water tank sleeve 8 and a sealing assembly. A pool wall sleeve 10 is arranged through the pool wall 24. The heavy water tank sleeve 8 is welded to the wall of the heavy water tank 22 as a whole. The heavy water tank sleeve 8 is open at the end and communicates with the heavy water tank 22. The outer sleeve 7 extends into the heavy water tank 22 through the pool wall sleeve 10 arranged on the pool wall 24 of the pool 23 and the heavy water tank sleeve 8, so that the end of the outer sleeve 7 is immersed in the heavy water. The slow positron generating assembly is arranged at the end of the outer sleeve 7 and is enclosed in the outer sleeve 7.

[0048] The slow positron generating assembly comprises an (n, γ) converter 1, a (γ, e+) converter 2 and a moderator 3 arranged in sequence along the axis of the outer sleeve 7. The (n, γ) converter 1 is arranged on the inner wall of the end of the outer sleeve 7, so that the heavy water in the heavy water tank 22 can directly take away the heat generated by the (n, γ) converter 1 in the form of convective heat exchange, thereby effectively improving the heat dissipation efficiency.

[0049] The vacuum cylinder 5 is arranged inside the outer sleeve 7, and the beam tube is arranged in the vacuum cylinder. The (γ, e+) converter 2 and the moderator 3 are arranged in the vacuum cylinder. The moderator 3 is fixedly arranged at the end of the beam tube 4, and the (γ, e+) converter 2 is arranged in connection with the moderator 3. The heat generated by the (γ, e+) converter 2 and the moderator 3 is transferred to the wall of the vacuum cylinder 5 through radiation heat transfer. The vacuum cylinder 5 and the outer sleeve 7 are filled with flowing helium, which can take away the heat of the wall of the vacuum cylinder 5 in the form of convective heat exchange, thereby achieving the heat dissipation effect.

[0050] The sealing assembly comprises a heavy water sealing mechanism and a light water sealing mechanism. The heavy water sealing mechanism seals the gap between the heavy water tank sleeve 8 and the outer sleeve 7 to prevent the heavy water in the heavy water tank 22 from leaking. The light water sealing mechanism seals the gap in the pool wall sleeve 10 to prevent the light water in the pool 23 from leaking. Specifically, the sealing assembly comprises a bellows 9, one end of which is connected to the heavy water tank sleeve 8, and the other end is connected to a port of the pool wall sleeve 10 located on the outer surface of the pool wall 24, and forms a seal respectively. The heavy water tank sleeve flange 11 is connected to the front end flange 12 of the bellows to form the heavy water sealing mechanism, which seals the heavy water in the heavy water tank 22, so that the heavy water cannot pass through the sealing surface formed by the heavy water tank sleeve flange 11 and the front end flange 12 of the bellows. The end of the bellows 9 extending to the pool wall sleeve 10 is provided with a rear end flange 16 of the bellows, and the end of the pool wall sleeve 10 located on the outer side of the pool wall 24 is provided with a pool wall sleeve flange 15. The pool wall sleeve flange 15 is connected to the rear end flange 16 of the bellows to form the light water sealing mechanism, so that the light water in the pool 23 cannot pass through the sealing surface formed by the pool wall sleeve flange 15 and the rear end flange 16 of the bellows. The end of the vacuum cylinder 5 is provided with a vacuum cylinder sealing flange 17, which is connected to the rear end flange 16 of the bellows and the pool wall sleeve flange 15 to form a double-layer sealing, which on the one hand further improves the sealing effect of the light water, and on the other hand forms a closed chamber between the vacuum cylinder 5 and the outer sleeve 7. The vacuum cylinder sealing flange 17 is provided with a vacuum cylinder helium gas inlet 18 and a vacuum cylinder helium gas outlet 19. Helium gas can flow into the vacuum cylinder helium gas inlet 18 and flow out of the vacuum cylinder helium gas outlet 19, forming a helium gas flow between the vacuum cylinder 5 and the outer sleeve 7 to achieve convective heat dissipation. Further, the bellows 9 is also provided with a bellows helium gas inlet 20 and a bellows helium gas outlet 21. Helium gas flows into the bellows helium gas inlet 20 and flows out of the bellows helium gas outlet 21 to form a helium gas flow between the outer sleeve 7 and the bellows 9, further improving the convective heat dissipation effect.

[0051] In the preferred embodiment, the pool wall sleeve 10, the bellows 9, the heavy water tank sleeve 8 and the outer sleeve 7 passing therethrough are integrally arranged in an inclined manner, so that the end of the outer sleeve 7 is the lower end. The opening of the pool wall sleeve 10 located on the outside of the pool 23 is higher than the top of the heavy water tank 22. The inclined design can further improve the safety of the reactor. Even if the sealing fails and leakage occurs, it can ensure that the light water in the pool 23 is at a safe water level to prevent accidents from worsening.

[0052] The installation method of the slow positron source is as follows: when the reactor is built, corresponding channels are reserved on the heavy water tank 22 and the pool wall 24, and the heavy water tank sleeve 8 is welded and the pool wall sleeve 10 is buried. The bellows 9 is installed in the state that the heavy water and light water in the reactor are emptied. Then, the outer sleeve 7 and the components inside it are inserted from the opening of the pool wall sleeve 10 and assembled.

[0053] After the reactor starts to operate, the neutrons generated in the core penetrate the wall of the outer sleeve 7 to bombard the (n, γ) converter 1 to generate γ photons, the energy deposition on the (n, γ) converter 1 is transferred to the outer sleeve 7 by contact heat transfer and taken away by the heavy water in the heavy water tank 22; the γ photons penetrate the wall of the vacuum cylinder 5 to bombard the (γ, e+) converter 2 to generate positrons, the positrons enter the moderator 3 to be moderated into slow positrons, the slow positrons are emitted from the core along the beam tube 4 and guided by the electromagnetic field generated by the coil 6 and other devices to form a slow positron beam output, and the heat generated by the (γ, e+) converter 2 and the moderator 3 is taken away by the helium gas flow.

[0054] The reactor-based slow positron source provided in the above embodiment uses the heavy water to directly conduct cooling on the front end of the outer sleeve 7, which effectively improves the heat dissipation capacity of the converter and the moderator, especially the heat dissipation capacity of the (n, γ) converter 1 subjected to the neutron bombardment in the core; due to the improvement of the cooling performance, the (n, γ) converter 1 can withstand a higher neutron fluence, and therefore the reactor-based slow positron source can output a slow positron beam with a higher beam intensity. Meanwhile, due to the inclined arrangement, the inherent safety of the reactor is effectively improved, and the risk of leakage of the coolant is reduced. The reactor-based slow positron source has a simple structure, does not introduce a complex new structure in the case of effectively improving the heat dissipation capacity, and is convenient to install and maintain, and the replacement of the converter and other work can be completed by operating outside the reactor.

[0055] Based on the design scheme of the slow positron source, an embodiment of another aspect of the present application provides a control method of the reactor-based slow positron source, which adjusts the distance between the slow positron generation assembly and the reactor core by adjusting the depth of the outer sleeve 7 inserted into the heavy water tank 22 (for example, the outer sleeve 7 with different lengths can be replaced), and then adjusts the neutron fluence of the (n, γ) converter 1 to adjust the slow positron beam intensity.

[0056] An embodiment of still another aspect of the present application provides a reactor which adopts the reactor-based slow positron source provided in the above embodiment. In a preferred embodiment, the reactor is provided with a plurality of reactor-based slow positron sources, and the outer sleeves of the reactor-based slow positron sources are inserted into the heavy water tank 22 at different inclined angles.

[0057] The above embodiments are intended to further illustrate the present application in combination with the drawings, so that those skilled in the art can understand the technical concept of the present application. Within the scope of the present application, optimization or equivalent replacement of the structures or method steps involved, and combination of the embodiments in different embodiments without structural and principle conflicts, all fall within the protection scope of the present application.

Claims

1. A reactor-based slow positron source, disposed in a reactor, wherein the reactor includes a water pool and a heavy water tank, the heavy water tank being disposed within the water pool, a gap existing between the wall of the heavy water tank and the wall of the water pool, the water pool containing light water, and the heavy water tank containing heavy water; characterized in that, include: The components include a slow positron generator assembly, an outer sleeve, a heavy water tank sleeve, and a sealing assembly. A through-wall sleeve is installed on the wall of the pool. The heavy water tank sleeve is integrally connected to the heavy water tank and communicates with the inside of the heavy water tank. The outer sleeve extends through the pool wall sleeve and the heavy water tank sleeve into the heavy water tank, so that the end of the outer sleeve is submerged in the heavy water; the slow positron generating component is disposed at the end of the outer sleeve and enclosed within the outer sleeve; The sealing assembly includes a heavy water sealing mechanism and a light water sealing mechanism. The heavy water sealing mechanism seals the gap between the heavy water tank sleeve and the outer sleeve; the light water sealing mechanism seals the gap inside the pool wall sleeve.

2. The stack-based slow positron source according to claim 1, characterized in that, The sealing assembly includes a bellows, which is sleeved outside the outer sleeve and connected to the heavy water tank sleeve and the pool wall sleeve, respectively.

3. The stack-based slow positron source according to claim 2, characterized in that, The corrugated pipe is connected to the heavy water tank sleeve at the end of the heavy water tank sleeve outside the water pool. Flanges are provided at the connection points, and the flanges of the corrugated pipe and the heavy water tank sleeve are connected to form the heavy water sealing mechanism.

4. The stack-based slow positron source according to claim 2 or 3, characterized in that, The corrugated pipe extends to one end of the pool wall sleeve and is provided with an end flange. The end of the pool wall sleeve located on the outside of the pool wall is provided with a flange and is connected to the end flange to form the light water sealing mechanism.

5. The stack-based slow positron source according to claim 1, 2, or 3, characterized in that, The bellows is provided with a helium inlet to allow helium to be filled into the bellows.

6. The stack-based slow positron source according to claim 1, 2, or 3, characterized in that, The slow positron generation assembly includes (n,γ) converters, (γ,e+) converters, and moderators arranged sequentially along the axial direction of the outer sleeve, with the (n,γ) converters disposed on the wall at the end of the outer sleeve.

7. The stack-based slow positron source according to claim 6, characterized in that, The slow positron generation assembly also includes a vacuum cylinder and a beam tube. The vacuum cylinder is inserted inside the outer sleeve, and the beam tube is inserted inside the vacuum cylinder. The (γ,e+) converter and the moderator are disposed inside the vacuum cylinder. The moderator is fixedly disposed at the end of the beam tube, and the (γ,e+) converter and the moderator are connected together.

8. The stack-based slow positron source according to claim 7, characterized in that, A sealing mechanism is provided between the vacuum cylinder and the pool wall sleeve.

9. The stack-based slow positron source according to claim 1, 2, or 3, characterized in that, The outer sleeve is inclined, wherein the end of the outer sleeve extending into the heavy water tank is the lower end, and the opening height of the pool wall sleeve outside the pool is higher than the top of the heavy water tank.

10. A method for controlling a reactor-based slow positron source, characterized in that, For controlling the slow positron beam intensity of the stack-based slow positron source as described in any one of claims 1 to 9, and comprising the following steps: Adjust the depth to which the outer sleeve is inserted into the heavy water tank to adjust the distance between the slow positron generator assembly and the reactor core.

11. A reactor, characterized in that, The reactor includes a reactor-based slow positron source, which is configured as a reactor-based slow positron source as described in any one of claims 1 to 9.

12. The reactor according to claim 11, characterized in that, The reactor includes multiple reactor-based slow positron sources; The outer sleeve in the slow positron source is inclined, wherein the end of the outer sleeve that extends into the heavy water tank is the lower end; The outer sleeves of the multiple stack-based slow positron sources have different tilt angles.

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