Primary neutron source assembly for nuclear-powered icebreaker

Abstract

The application discloses a primary neutron source assembly for a nuclear power icebreaker, which comprises a hoisting joint, a connecting pipe and a primary neutron source rod connected in sequence along an axial direction. The connecting pipe constitutes a long rod-shaped connecting structure, so that the assembly can pass through a neutron source guide assembly from above an in-pile component and be inserted into a reactor core after installation of a compression part is completed; the hoisting joint is provided with a pin matched with a limiting structure to realize axial limiting. A primary neutron source body and an axial positioning structure are arranged in the primary neutron source rod, so that the source body is located at a predetermined height of a reactor active section. The assembly is also provided with a pressure balance through hole, a radial gap and a helium filling structure, so as to improve heat transfer, pressure balance and heat expansion adaptability, and meet installation and operation reliability requirements of the reactor of the nuclear power icebreaker.

Description

Technical Field

[0001] This application belongs to the field of nuclear reactor engineering technology, specifically relating to a primary neutron source assembly for a nuclear-powered icebreaker. Background Technology

[0002] During the physical startup of a nuclear reactor, the reactor is typically in a deep subcritical state, and relying solely on control rod boosting is insufficient to achieve a core neutron flux level that the nuclear measurement system can stably monitor. To increase the neutron flux during startup and ensure reliable core status indication by the nuclear measurement system, a primary neutron source is usually installed within the core. This primary neutron source continuously releases neutrons, providing the necessary neutron counting basis for the physical startup after the initial fuel loading, control rod operation, and critical approach process.

[0003] Currently, most primary neutron source assemblies are fixed to fuel assemblies. When using this type of structure, a specialized loading tool is typically used to install the primary neutron source assembly onto the designated fuel assembly before the reactor clamping components are installed. This installation method places high demands on the operating space above the reactor core, the installation sequence, and underwater operating conditions.

[0004] The reactor compartments of civilian nuclear-powered icebreakers are compactly arranged, and the installation sequence of reactor components and related equipment is limited by hull space and overall assembly processes. In some installation scenarios, the primary neutron source assembly needs to be installed after the fuel assemblies and clamping components have been installed. Traditional primary neutron source assemblies, fixed to the fuel assemblies, cannot pass through the already installed clamping components and neutron source guide structures, making them unsuitable for this installation sequence.

[0005] Furthermore, primary neutron sources are highly radioactive. If the components are short or require operators to connect, position, and lock them close to the source, it will increase the radiation protection pressure during installation. Icebreakers may also be subjected to loads such as vibration, tilting, and impact during operation. The primary neutron source components need to maintain reliable axial positioning within the reactor core to prevent displacement, loosening, or abnormal collisions with surrounding structures.

[0006] During reactor operation, the components are simultaneously exposed to high temperature, high pressure, and radiation environments. Dimensional differences may arise between the primary neutron source, the cladding structure, and the external cladding due to material thermal expansion and radiation effects; the hollow inlet may also experience significant pressure differentials if the internal and external pressures cannot be balanced in a timely manner. Inadequate design of source positioning, gap compensation, heat transfer, sealing, or pressure balancing may affect the structural integrity and operational reliability of the components.

[0007] Therefore, it is necessary to provide a primary neutron source assembly for nuclear-powered icebreakers that can be inserted into the reactor core from above the reactor internals after the clamping components are installed, while taking into account the requirements for precise positioning of the neutron source, assembly fixation, radiation protection, thermal expansion compensation, heat transfer and pressure balance. Summary of the Invention

[0008] The purpose of this application is to provide a primary neutron source assembly for nuclear-powered icebreakers, in order to solve the problem that existing primary neutron source assemblies are difficult to adapt to the special installation sequence and compact layout conditions of nuclear-powered icebreaker reactors, and to improve the radiation safety, in-reactor positioning accuracy and operational reliability of the primary neutron source assembly during installation.

[0009] The technical solution to achieve the purpose of this application is as follows: This application provides a primary neutron source assembly for a nuclear-powered icebreaker, comprising a lifting joint, a connecting pipe, and a primary neutron source rod connected sequentially along the axial direction. The connecting pipe is an axially extending long tubular connector, with its upper end connected to the lifting joint and its lower end connected to the primary neutron source rod, so that the primary neutron source assembly forms a long rod-shaped structure capable of passing through a neutron source guide assembly above the reactor inboard components and inserting into the reactor core. The lifting joint is used to connect with external lifting tools and is provided with a radially extending pin, which is used to cooperate with a limiting structure on the neutron source guide assembly to axially limit the primary neutron source assembly. A primary neutron source body is disposed inside the primary neutron source rod, and the axial length of the connecting pipe is set such that when the pin is engaged with the limiting structure, the primary neutron source body is located at a predetermined height position in the reactor active section.

[0010] Optionally, the upper and lower ends of the connecting pipe are respectively provided with internal threads, and the lifting joint and the primary neutron source rod are respectively threaded to the upper and lower ends of the connecting pipe.

[0011] Optionally, the upper part of the nozzle is provided with a pressure balancing through hole, which connects the internal space of the nozzle with the reactor coolant environment to balance the internal and external pressures of the nozzle.

[0012] Optionally, the primary neutron source rod includes a cladding tube, an upper plug, a lower plug, the primary neutron source body, a gasket, a clamping tube, and a support tube; the upper plug and the lower plug are respectively welded to the upper and lower ends of the cladding tube, and the primary neutron source body, the gasket, the clamping tube, and the support tube are all disposed inside the cladding tube.

[0013] Optionally, the gasket, the clamping tube, and the support tube together constitute the axial positioning structure of the primary neutron source, and the axial dimension of the axial positioning structure is set to keep the primary neutron source at the predetermined height position of the reactor active section.

[0014] Optionally, a radial gap is provided between the primary neutron source and the cladding tube, the radial gap being used to compensate for the difference in thermal expansion between the primary neutron source and the cladding tube.

[0015] Optionally, the casing tube is filled with helium; the lower end is provided with an axially penetrating gas through hole, which is sealed after helium is filled into the casing tube.

[0016] Optionally, the wall of the support tube is provided with transverse holes, which connect the inner and outer spaces of the support tube to allow helium gas to flow into the gap area inside the cladding tube.

[0017] Optionally, the primary neutron source is provided with a stainless steel cladding layer on the outside, and the cladding tube constitutes a second cladding structure located outside the stainless steel cladding layer.

[0018] Optionally, the limiting structure is a slot or limiting hole provided on the neutron source guide assembly, and the pin is engaged in the slot or limiting hole when the hoisting joint reaches the installation position.

[0019] Optionally, the primary neutron source is a californium-252 neutron source.

[0020] Optionally, the connecting pipe, the casing pipe, the upper plug, the lower plug, the clamping pipe, and the support pipe are all made of stainless steel.

[0021] The beneficial technical effects of this application are as follows: The primary neutron source assembly for nuclear-powered icebreakers provided in this application includes a lifting joint, a long tubular connector, and a primary neutron source rod connected sequentially along the axial direction. The lifting joint engages with the limiting structure of the neutron source guide assembly via radially extending pins. A primary neutron source body is housed within the primary neutron source rod, and the axial length of the connector ensures that the primary neutron source body is positioned at a predetermined height within the reactor active section when the assembly is fully positioned. Through the aforementioned long rod-like structure, after the clamping components are installed, the assembly can be lifted from above the reactor core using external lifting tools, passing through the neutron source guide assembly and inserting into the reactor core. This adapts to the compact compartments and special installation sequences of nuclear-powered icebreakers, while simultaneously increasing the distance between operators and the primary neutron source body, reducing radiation risks during installation. The engagement of the pins and the limiting structure improves the axial positioning reliability of the assembly under ship vibration, tilting, and impact environments. The length of the connector and the internal positioning structure of the primary neutron source rod together ensure the height accuracy of the primary neutron source body within the active section, thereby meeting the neutron flux requirements for physical activation and providing a reliable foundation for thermal expansion compensation, heat transfer, pressure balance, and long-term structural integrity of the assembly. Attached Figure Description

[0022] Figure 1 A schematic diagram of the overall structure of the primary neutron source assembly for a nuclear-powered icebreaker provided in this application; Figure 2 A cross-sectional schematic diagram of the nozzle of the primary neutron source assembly for a nuclear-powered icebreaker provided in this application; Figure 3 A cross-sectional schematic diagram of the primary neutron source rod of the primary neutron source assembly for a nuclear-powered icebreaker provided in this application.

[0023] In the figure: 1-lifting joint, 2-pin, 3-connector, 4-primary neutron source rod, 31-pressure balance through hole, 41-upper plug, 42-cladding tube, 43-lower plug, 44-primary neutron source body, 45-gasket, 46-compression tube, 47-support tube, 48-lateral small hole, 49-axial inflation through hole. Detailed Implementation

[0024] To enable those skilled in the art to better understand this application, the technical solution of this application is clearly and completely described below with reference to the accompanying drawings and specific embodiments. Obviously, the following specific embodiments are only some embodiments of this application and are not intended to limit the scope of protection of this application. Equivalent substitutions, modifications, or improvements made by those skilled in the art based on the content of this application without departing from the concept of this application should all fall within the scope of protection of this application.

[0025] like Figures 1 to 3 As shown, this embodiment provides a primary neutron source assembly for a nuclear-powered icebreaker. The assembly is generally slender and rod-shaped, including a lifting joint 1, a connecting pipe 3, and a primary neutron source rod 4 connected sequentially from top to bottom along the axial direction. The assembly, through the lifting joint 1 and external lifting tools, traverses the distance between the upper operating area of ​​the reactor internals and the reactor core via the connecting pipe 3, and delivers the primary neutron source rod 4, located at the lower end of the assembly, into the corresponding region of the reactor's active section.

[0026] The lifting joint 1 is located at the upper end of the primary neutron source assembly and serves as the operating interface between the assembly and external lifting tools. The upper part of the lifting joint 1 can be equipped with a connecting section that mates with the lifting tools. The specific form of the connecting section can be threaded, snap-fit, sleeved, or other detachable connection methods, depending on the lifting tools. Through the lifting joint 1, operators can perform lifting, alignment, lowering, and removal operations of the assembly above the in-core components without needing to operate directly near the primary neutron source body 44.

[0027] The lifting joint 1 is equipped with a pin 2 extending radially outward. A limiting structure is provided on the upper part or corresponding installation position of the neutron source guide assembly. This limiting structure can be a slot, a limiting hole, or other structure capable of forming an axial limit with the pin 2. When the primary neutron source assembly is lowered to the predetermined installation position, the pin 2 enters and engages with the limiting structure, suspending or supporting the primary neutron source assembly at a designated position within the in-core components, and restricting further downward movement of the assembly or significant axial movement during operation.

[0028] The pin 2 and the limiting structure can be fitted with guide surfaces, chamfers, or assembly gaps as needed for installation, so that the pin 2 can smoothly enter the slot or limiting hole during the assembly lowering process. The limiting structure can also have a circumferential positioning function, so that the lifting joint 1 maintains a predetermined circumferential posture after reaching the installation position. Through this mechanical limiting method, the assembly can remain stable when subjected to vibration, tilting, or impact loads during the navigation of the nuclear-powered icebreaker.

[0029] Connector 3, located between lifting joint 1 and primary neutron source rod 4, is a long, axially extending tubular connector. Connector 3 serves both to transfer the assembly's lifting and self-weight loads and to provide sufficient axial length to allow external lifting tools and personnel to remain away from the highly radioactive primary neutron source 44 located at the lower end of the assembly. The length of connector 3 is determined comprehensively based on its installation position above the in-reactor components, the length of the neutron source guiding assembly, the location of the reactor's active section, and the available lifting space.

[0030] In this embodiment, the upper and lower ends of the connecting pipe 3 are respectively machined with internal threads. The lower part of the lifting joint 1 is provided with an external thread that mates with the internal thread at the upper end of the connecting pipe 3, and the upper part of the primary neutron source rod 4 is provided with an external thread that mates with the internal thread at the lower end of the connecting pipe 3, thereby detachably connecting the lifting joint 1, the connecting pipe 3, and the primary neutron source rod 4 into a whole. The threaded connection can be equipped with mechanical anti-loosening, spot welding anti-loosening, or other reliable anti-loosening structures according to the anti-loosening requirements of nuclear-grade equipment.

[0031] like Figure 2 As shown, a pressure balancing through-hole 31 is provided at the upper part of the nozzle 3. The pressure balancing through-hole 31 penetrates the pipe wall of the nozzle 3, connecting the internal space of the nozzle 3 with the reactor coolant environment. When the components are heated or depressurized along with the reactor, the reactor coolant can enter or leave the interior of the nozzle 3 through the pressure balancing through-hole 31, so that the pressure inside and outside the nozzle 3 can be made consistent in a timely manner, avoiding local deformation or instability of the nozzle 3 due to large pressure differences.

[0032] The pressure balancing through-hole 31 is preferably located near the upper end of the nozzle 3 to reduce the impact of foreign matter ingress and deposition on the connectivity of the through-hole, and to facilitate manufacturing and inspection. The number, diameter, and circumferential position of the pressure balancing through-hole 31 can be determined according to the pressure balancing speed, nozzle strength, and flow-induced vibration requirements, as long as pressure connectivity between the internal space of the nozzle 3 and the reactor coolant environment can be achieved.

[0033] like Figure 3 As shown, the primary neutron source rod 4 includes an upper plug 41, a cladding tube 42, a lower plug 43, a primary neutron source body 44, a gasket 45, a clamping tube 46, and a support tube 47. The cladding tube 42 is a tubular covering component extending axially. The upper plug 41 and the lower plug 43 are respectively assembled at the upper and lower ends of the cladding tube 42 and are sealed and welded to the cladding tube 42, thereby forming a sealed space to accommodate the primary neutron source body 44 and its positioning components.

[0034] A primary neutron source 44 is housed within the cladding tube 42. The primary neutron source 44 may be a californium-252 neutron source. Californium-252 can continuously release neutrons through spontaneous fission. When the primary neutron source 44 is located at a predetermined height in the reactor active section, it can increase the neutron flux level in the subcritical state of the reactor core, enabling the nuclear measurement system to obtain an effective count above the background, and providing monitoring conditions for the reactor physical start-up process.

[0035] The primary neutron source 44 is externally covered with a stainless steel cladding layer for the first layer of sealing and covering of the radioactive source material; the cladding tube 42 is located outside the stainless steel cladding layer, forming a second layer of cladding structure. The double-layer cladding can improve the sealing safety of the primary neutron source 44 during manufacturing, transportation, installation and in-reactor operation, and reduce the possibility of direct contact between the source material and the reactor coolant environment.

[0036] The gasket 45, the clamping tube 46, and the support tube 47 are disposed inside the cladding tube 42 and together constitute the axial positioning structure of the primary neutron source 44. The axial positioning structure is located on the upper and lower sides of the primary neutron source 44, respectively, or by combining gaskets 45, clamping tubes 46, and support tubes 47 of different axial lengths, to limit the primary neutron source 44 and keep it in a predetermined axial position within the cladding tube 42.

[0037] When determining the axial position of the primary neutron source 44, a dimensional chain can be established based on the installation reference of the pin 2 and the neutron source guide assembly limiting structure, the axial length of the connecting pipe 3, the connection dimensions of the primary neutron source rod 4 and the connecting pipe 3, the structural dimensions of the upper plug 41 and the lower plug 43, and the height position of the reactor active section. By designing the dimensional chain, after the pin 2 is engaged with the limiting structure, the center or effective source region of the primary neutron source 44 is located at the predetermined height position required by the reactor active section.

[0038] A radial gap is provided between the primary neutron source 44 and the cladding tube 42. This radial gap can absorb the radial dimensional differences between the cladding layer of the primary neutron source 44 and the cladding tube 42 caused by manufacturing tolerances, temperature changes and irradiation, avoid the primary neutron source 44 from applying excessive contact load to the cladding tube 42 due to limited thermal expansion, and also reduce the risk of source jamming or local stress concentration in the cladding.

[0039] The cladding tube 42 is filled with helium gas at a certain pressure. Helium gas has good chemical stability and heat transfer properties, and can fill the gaps between the primary neutron source 44 and the cladding tube 42, as well as around the positioning components, transferring the decay heat generated by the primary neutron source 44 to the cladding tube 42, which is then carried away by the reactor coolant. Helium gas can also provide a controlled atmosphere inside the cladding, reducing the possibility of adverse chemical reactions occurring in the internal components.

[0040] The lower plug 43 is provided with an axially penetrating inflation port 49. During the manufacturing process, after the upper plug 41 and the lower plug 43 are sealed to the casing tube 42 and the internal leak test of the casing is passed, the interior of the casing tube 42 can be evacuated and filled with helium through the axial inflation port 49. After reaching the predetermined inflation state, the axial inflation port 49 is fused and sealed, and the sealing part is checked for sealing performance.

[0041] The support tube 47 has transverse holes 48 in its wall, which connect the inner and outer spaces of the support tube 47. When helium is filled through the axial inflation port 49, the helium can enter other gap areas outside the support tube 47 and inside the casing tube 42 through the transverse holes 48, thereby improving the uniformity of inflation and reducing local closed spaces caused by the positioning components. The transverse holes 48 can also promote the balance of gas pressure inside and outside the support tube 47 when the temperature changes.

[0042] The connecting pipe 3, cladding tube 42, upper plug 41, lower plug 43, clamping tube 46, and support tube 47 can all be made of stainless steel, for example, austenitic stainless steel of appropriate grade selected according to the reactor coolant environment, irradiation conditions, and welding requirements. The gasket 45 can also be made of a metal compatible with the cladding tube 42. All materials should meet the requirements for strength, corrosion resistance, irradiation stability, and manufacturability under in-reactor operating conditions.

[0043] The primary neutron source rod 4 in this embodiment can be manufactured and assembled as follows: First, the cladding tube 42, upper plug 41, lower plug 43, gasket 45, clamping tube 46 and support tube 47 are cleaned and their dimensions are checked; then, the support tube 47, clamping tube 46, gasket 45 and primary neutron source 44 are sequentially installed into the cladding tube 42 according to a predetermined dimensional chain, so that the primary neutron source 44 is in the designed axial position; then, the upper plug 41 and lower plug 43 are installed into both ends of the cladding tube 42 and sealed by welding.

[0044] After the end plug is sealed, the neutron source rod 4 is inspected for sealing. Once the inspection is passed, a vacuum is drawn through the axial filling hole 49 on the lower end plug 43, and helium is introduced. The helium diffuses through the transverse holes 48 on the support tube 47 into the various gap areas inside the cladding tube 42. After filling, the axial filling hole 49 is sealed, and the appearance, dimensions, and sealing are inspected again.

[0045] After the primary neutron source rod 4 is manufactured, its upper end is connected to the lower end of the connecting pipe 3, and the lifting connector 1 is connected to the upper end of the connecting pipe 3 to form a complete primary neutron source assembly. During the assembly process, the engagement length and tightness of each threaded connection should be controlled, and the pin 2, pressure balance through hole 31, and outer surface of the primary neutron source rod 4 should be inspected to ensure that the assembly shape can smoothly pass through the neutron source guide assembly.

[0046] During on-site installation at the reactor, the fuel assemblies and clamping components may already be installed. Operators connect the external lifting equipment to lifting connector 1, lift the primary neutron source assembly, and align the primary neutron source rod 4 and connecting pipe 3 with the neutron source guide assembly inlet at the top of the in-core components. The assembly is then slowly lowered, allowing the primary neutron source rod 4 and connecting pipe 3 to move towards the reactor core along the neutron source guide assembly.

[0047] When the lifting joint 1 reaches the installation position, the radially extending pin 2 enters the slot or limiting hole on the neutron source guide assembly, thereby axially limiting the assembly. After limiting, the external lifting tool is disconnected from the lifting joint 1. At this time, the primary neutron source body 44 is located at the predetermined height position of the reactor active section under the combined action of the length of the connecting pipe 3 and the axial positioning structure inside the primary neutron source rod 4.

[0048] During reactor operation, pin 2 bears the load required for axial positioning of the assembly, and nozzle 3 transmits the structural load between lifting joint 1 and primary neutron source rod 4. Pressure balancing through-hole 31 maintains communication between the inside of nozzle 3 and the reactor coolant environment; helium gas inside cladding tube 42 transfers heat generated by primary neutron source 44 to cladding tube 42, while radial clearance compensates for the thermal expansion difference between primary neutron source 44 and cladding tube 42. These structures collectively ensure the assembly maintains functional integrity under conditions of high temperature, high pressure, irradiation, and ship vibration and tilting.

[0049] When it is necessary to dismantle or replace the primary neutron source assembly, the external lifting tool can be reconnected to the lifting joint 1, allowing the pin 2 to disengage from the limiting structure of the neutron source guide assembly, and then the assembly can be lifted upwards along the neutron source guide assembly. The long rod-like structure allows the dismantling operation to be completed above the in-core components, and maintains a large distance between the operators and the primary neutron source body 44.

[0050] This embodiment utilizes a long rod-shaped assembly structure formed by the lifting joint 1, the connecting pipe 3, and the primary neutron source rod 4 to achieve remote insertion and removal after the clamping components are installed; reliable axial fixation is achieved through the cooperation of the pin 2 and the limiting structure; the height position of the primary neutron source body 44 is ensured by the length of the connecting pipe 3 and the internal positioning structure of the primary neutron source rod 4; and the sealing, heat transfer, thermal expansion adaptation, and pressure balance capabilities of the component are improved through double-layer coating, radial gap, helium filling structure, transverse small hole 48, and pressure balance through hole 31.

[0051] The present application has been described above with reference to the accompanying drawings and specific embodiments, but the present application is not limited to the specific embodiments described above. Connection methods, welding processes, inspection methods, dimensional determination methods, and hoisting tool types not described in detail in this application can all be implemented using existing technologies in the field.

Claims

1. A primary neutron source assembly for a nuclear-powered icebreaker, characterized in that, It includes a hoisting joint (1), a pipe (3), and a primary neutron source rod (4) connected sequentially along the axial direction. The connecting pipe (3) is a long tubular connector extending along the axial direction. The upper end of the connecting pipe (3) is connected to the hoisting joint (1), and the lower end of the connecting pipe (3) is connected to the primary neutron source rod (4), so that the primary neutron source assembly forms a long rod-shaped structure that can pass through the neutron source guide assembly from above the in-core components and be inserted into the core. The lifting joint (1) is used to connect with external lifting tools and is provided with a pin (2) extending radially. The pin (2) is used to cooperate with the limiting structure on the neutron source guide assembly to axially limit the primary neutron source assembly. The primary neutron source rod (4) contains a primary neutron source body (44), and the axial length of the connecting pipe (3) is set as follows: When the pin (2) engages with the limiting structure, the primary neutron source (44) is located at a predetermined height in the active section of the reactor.

2. The primary neutron source assembly for a nuclear-powered icebreaker according to claim 1, characterized in that, The upper and lower ends of the connector (3) are respectively provided with internal threads, and the hoisting joint (1) and the primary neutron source rod (4) are respectively threaded to the upper and lower ends of the connector (3).

3. The primary neutron source assembly for a nuclear-powered icebreaker according to claim 1, characterized in that, The upper part of the connector (3) is provided with a pressure balancing through hole (31), which connects the internal space of the connector (3) with the reactor coolant environment to balance the internal and external pressures of the connector (3).

4. The primary neutron source assembly for a nuclear-powered icebreaker according to claim 1, characterized in that, The primary neutron source rod (4) includes a casing tube (42), an upper plug (41), a lower plug (43), the primary neutron source body (44), a gasket (45), a clamping tube (46), and a support tube (47). The upper plug (41) and the lower plug (43) are respectively welded to the upper and lower ends of the cladding tube (42). The primary neutron source (44), the gasket (45), the clamping tube (46) and the support tube (47) are all disposed inside the cladding tube (42).

5. The primary neutron source assembly for a nuclear-powered icebreaker according to claim 4, characterized in that, The gasket (45), the clamping tube (46), and the support tube (47) together constitute the axial positioning structure of the primary neutron source (44), and the axial dimension of the axial positioning structure is set to keep the primary neutron source (44) at the predetermined height position of the reactor active section.

6. The primary neutron source assembly for a nuclear-powered icebreaker according to claim 4, characterized in that, A radial gap is provided between the primary neutron source (44) and the cladding tube (42), the radial gap being used to compensate for the difference in thermal expansion between the primary neutron source (44) and the cladding tube (42).

7. The primary neutron source assembly for a nuclear-powered icebreaker according to claim 4, characterized in that, The casing tube (42) is filled with helium; the lower end plug (43) is provided with an axially penetrating gas through hole (49), which is sealed after helium is filled into the casing tube (42).

8. The primary neutron source assembly for a nuclear-powered icebreaker according to claim 7, characterized in that, The wall of the support tube (47) is provided with a transverse hole (48), which connects the inner and outer spaces of the support tube (47) so that helium gas can flow into the gap area inside the cladding tube (42).

9. The primary neutron source assembly for a nuclear-powered icebreaker according to claim 4, characterized in that, The primary neutron source (44) is provided with a stainless steel cladding layer on the outside, and the cladding tube (42) constitutes a second cladding structure located outside the stainless steel cladding layer.

10. The primary neutron source assembly for a nuclear-powered icebreaker according to claim 1, characterized in that, The limiting structure is a slot or limiting hole provided on the neutron source guide assembly, and the pin (2) is engaged in the slot or the limiting hole when the hoisting joint (1) reaches the installation position.

11. The primary neutron source assembly for a nuclear-powered icebreaker according to claim 4, characterized in that, The primary neutron source (44) is a californium-252 neutron source.

12. The primary neutron source assembly for a nuclear-powered icebreaker according to claim 4, characterized in that, The connecting pipe (3), the casing pipe (42), the upper plug (41), the lower plug (43), the clamping pipe (46), and the support pipe (47) are all made of stainless steel.

Images