Emergency shutdown device and method for solid reactor core

Abstract

The invention discloses an emergency shutdown device for a solid reactor core. The emergency shutdown device comprises a safety rod, a guide cylinder and a driving mechanism, wherein the safety rod comprises a cladding and a neutron absorber, and can slide into a reactor core along the axial direction; the guide cylinder is arranged in a reactor core and provides a guide slide way for the safety rod, and the guide slide way is provided with a horizontally arranged bottom surface and inclined surfaces on two sides; and the driving mechanism provides axial driving for the safety rod. A cushion block is arranged on the lower surface of the cladding, and the safety rod abuts against the inclined wall face through the cushion block and is separated from the bottom face. The emergency shutdown device for the solid reactor core can effectively reduce the sliding resistance of the safety rod, reduce the cladding wear of the safety rod and improve the shutdown response speed and reliability. The invention also provides an emergency shutdown method for the solid reactor core.

Description

Technical Field

[0001] The invention belongs to the field of nuclear power, and in particular relates to a solid-state reactor core emergency shutdown device and method. Background Art

[0002] As a new type of reactor, the heat pipe micro reactor does not have a primary circuit containing liquid cooling medium, but uses solid core heat transfer, using fuel assemblies and solid core matrix to transfer heat to heat pipes, which output the heat generated by the core fission reaction. This difference in structure and principle makes the emergency shutdown device of the heat pipe micro reactor different from that of the traditional pressurized water reactor. The heat pipe micro reactor cannot use the downward insertion control rod or the method of adding neutron absorber in the primary circuit for emergency shutdown, but needs to insert the safety rod horizontally along the core axis.

[0003] Patent CN114708994A discloses a safety rod shutdown drive mechanism, which automatically releases the safety rod when the safety device of the reactor is powered off and pushes the safety rod into the core by the energy storage spring to achieve shutdown. However, in actual operation, the safety rod is relatively long and is prone to get stuck during long-distance horizontal movement due to factors such as matrix debris or excessive friction, which poses a risk of untimely shutdown; at the same time, when the shutdown state needs to be ended and the safety rod needs to be pulled out, there is also a risk of getting stuck.

[0004] Therefore, providing a solid-state core emergency shutdown device with higher safety and reliability is of great significance for improving the safety of heat pipe micro-reactors. Summary of the invention

[0005] The purpose of the present invention is to provide a solid-state core emergency shutdown device to improve the reliability of the emergency shutdown device. The present invention also provides a solid-state core emergency shutdown method.

[0006] According to an embodiment of one aspect of the present invention, there is provided a solid-state core emergency shutdown device, the device comprising:

[0007] A safety rod comprises a cladding and a neutron absorber, wherein the neutron absorber is enclosed in the cladding, and a pad is provided on the lower surface of the cladding; the safety rod can slide axially into the reactor core;

[0008] A guide cylinder, which is arranged in the reactor core and provides a guide slideway for the safety rod, wherein the guide slideway has a horizontally arranged bottom surface, and two sides of the bottom surface are connected to inclined sloping walls;

[0009] a driving mechanism, providing axial drive for the safety rod, so that the safety rod can be inserted into or withdrawn from the reactor core;

[0010] The cushion block of the safety bar matches the inclined wall surface of the guide slideway, and the safety bar abuts against the inclined wall surface through the cushion block and is separated from the bottom surface.

[0011] The device can effectively reduce the friction of the safety rod when inserting and withdrawing it from the reactor core, reduce the risk of the safety rod getting stuck during the shutdown process, and improve the safety and reliability of the reactor.

[0012] Furthermore, in some embodiments, the safety rod further includes an air cavity spring, wherein the air cavity spring is disposed at one end of the neutron absorber in the cladding, and the air cavity spring presses the neutron absorber axially.

[0013] The air cavity spring can press against the neutron absorber to limit the position of the neutron absorber; at the same time, the elasticity of the air cavity spring itself can absorb the axial size change of the neutron absorber due to temperature or irradiation growth, preventing the safety rod from being deformed or swollen when placed in the reactor core.

[0014] Furthermore, in some embodiments, the cross-section of the guide slideway is configured as a regular hexagon.

[0015] Furthermore, in some embodiments, a lubricating coating is provided on the surface of the inclined wall of the guide slideway.

[0016] Furthermore, in some embodiments, the pad is made of elastic material.

[0017] Furthermore, in some embodiments, a guide section is provided at the end of the safety rod that first enters the reactor core when the safety rod moves axially, and the guide section is configured as a conical structure.

[0018] The conical structure can play a guiding role when the safety rod is inserted into the core, thereby improving the response speed of the shutdown process.

[0019] Furthermore, in some embodiments, the driving device includes a passive driving mechanism and a locking mechanism, wherein the locking mechanism axially locks the safety rod in a locked state, and the passive driving mechanism drives the safety rod to be inserted into the reactor core when the locking structure is unlocked.

[0020] Furthermore, in some embodiments, the passive driving mechanism is configured as a pressure accumulator spring.

[0021] Furthermore, in some embodiments, the shell of the safety rod is sealed by welding.

[0022] According to another embodiment of the present invention, a solid-state core emergency shutdown method is provided. The method uses the solid-state core emergency shutdown device provided in any of the above embodiments and includes the following steps:

[0023] Assembling the solid core emergency shutdown device and installing the guide cylinder into the reactor core;

[0024] Connecting the shutdown control device of the solid-state core to the drive mechanism signal;

[0025] When the shutdown control device sends a shutdown signal, the driving mechanism drives the safety rod to be inserted into the reactor core along the guide slide to realize shutdown.

[0026] This method can effectively improve the timeliness and reliability of emergency shutdown and effectively reduce the risk that the reactor cannot be shut down in time under accident conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of a safety rod and a guide cylinder in one embodiment;

[0028] Figure 2 This is a schematic diagram of the structure of a safety rod in one embodiment;

[0029] Figure 3 A schematic diagram of a cross-sectional structure of a safety rod and a guide cylinder in cooperation with each other in one embodiment;

[0030] Figure 4 Schematic diagram of the rear end plug structure of the safety rod in one embodiment.

[0031] Meaning of the reference symbols:

[0032] 1- Safety rod;

[0033] 11- front end plug;

[0034] 12- rear end plug;

[0035] 13-cladding;

[0036] 14- Pad;

[0037] 15- Neutron absorber;

[0038] 16-guide section;

[0039] 2-guide cylinder;

[0040] 21-Bottom surface;

[0041] 22-Sloped wall.

[0042] The purpose of the above drawings is to explain the present invention in detail so that those skilled in the art can understand the technical concept of the present invention, but it is not intended to limit the present invention. For the sake of simplicity, the above drawings only schematically illustrate the structures related to the technical features of the present invention, and do not strictly follow the actual proportions to draw the complete structure and all details. DETAILED DESCRIPTION

[0043] The present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0044] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The phrase appearing in various locations in the specification does not necessarily refer to the same embodiment, nor is it limited to mutually exclusive independent or alternative embodiments. Those skilled in the art should be able to understand that the embodiments herein may be combined with other embodiments without causing structural conflicts.

[0045] In the description of this article, unless otherwise clearly specified and limited, the technical terms "installed", "connected", "connected" and the like should be understood in a broad sense, for example, it can be a movable connection, a fixed connection or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of this application can be understood according to specific circumstances.

[0046] In the description of this document, terms indicating orientation or positional relationships, such as "up", "down", "left", "right", "horizontal", "vertical", "height", "length", and "width", are intended to accurately describe the embodiments and simplify the description, but are not intended to limit the parts or structures involved to have a specific orientation, be installed or operate in a specific orientation, and should not be construed as a limitation on the embodiments in this document.

[0047] In the description of this article, 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 quantity, specific order or primary and secondary relationship of the described technical features. In the description of this article, the meaning of "plurality" is at least two.

[0048] The heat pipe micro reactor is a solid core reactor that uses heat pipes as the main heat transfer element, uses the fuel assembly matrix itself as the heat transfer medium, and cooperates with the characteristics of the heat pipe to complete the heat release of the nuclear fuel. Unlike the rod bundle fuel assembly of the pressurized water reactor, the heat pipe micro reactor fuel assembly does not have a guide tube inside, and unlike the vertical structure of the pressurized water reactor core, the heat pipe micro reactor core is a horizontal structure, and the influence of gravity needs to be considered in particular. Therefore, conventional pressurized water reactor reactivity control components cannot be applied to solid core fuel assemblies, and need to be designed specifically for the characteristics of solid core fuel assemblies.

[0049] The safety rod is an important reactivity control component in the heat pipe micro-reactor. The safety rod is set at the center of the core and is fully extended when the core is operating normally. After the core is shut down or in an emergency, the safety shutdown rod will be fully inserted into the core horizontally to ensure that the core enters and maintains a subcritical state. Because of its safety importance, the safety rod must be designed to be highly reliable and take into account wear and radiation effects (such as fuel consumption, changes in physical properties, and gas generation). When the reactor needs to be shut down in an emergency, it is necessary to ensure that the safety rod can respond quickly and be inserted into the reactor core to reduce reactivity in time to avoid further deterioration of the accident. Since the core operating temperature of the heat pipe micro-reactor is high and it is under irradiation conditions for a long time, it is necessary to further avoid the safety rod from failing to reach the working position in time due to the swelling and cracking of the core matrix due to radiation or excessive friction due to factors such as thermal deformation.

[0050] In order to solve these problems, an embodiment of one aspect of the present invention provides a solid-state core emergency shutdown device.

[0051] like Figure 1 As shown, the device includes a safety rod 1, a guide cylinder 2 and a driving mechanism (not shown).

[0052] The safety rod 1 includes a cladding 13, and a front plug 11 and a rear plug 12 are respectively provided at both ends of the cladding 13, wherein the end where the rear plug 12 is located faces the reactor core and enters the reactor core first during an emergency shutdown. Figure 2 A neutron absorber 15 is enclosed in the cladding 13. When the safety rod 1 is inserted into the reactor core, the neutron absorber 15 can absorb neutrons to reduce the reactivity of the reactor core, thereby achieving shutdown.

[0053] The guide cylinder 2 is arranged in the reactor core, and provides a guide slideway for the safety rod 1, and provides guidance for the safety rod 1 when the safety rod 1 slides axially. The guide slideway includes a horizontally arranged bottom surface 21, and the two sides of the bottom surface 21 are inclined wall surfaces 22. A pad 14 is arranged on the lower outer surface of the cladding 13, and the pad 14 cooperates with the inclined wall surface 22. When the safety rod 1 slides axially along the guide slideway, the pad 14 abuts against the inclined wall surface 22 and slides, and props up the safety rod 1 as a whole, so that the safety rod 1 is separated from the bottom surface 21.

[0054] In a preferred embodiment, the guide tube 2 is configured as a hexagon as a whole, and the cross-section of the guide slide is configured as a regular hexagon to match the fuel assembly and matrix structure of the heat pipe micro-reactor core, thereby reducing the difficulty of assembly.

[0055] By providing the pad 14, the friction between the cladding 13 and the guide cylinder 2 can be reduced, and the wear of the cladding 13 can be prevented while reducing the friction, so as to extend the service life of the cladding 13. In a preferred embodiment, the pad 14 is made of an elastic material, such as a high-temperature resistant alloy, so that the pad 14 can adapt to the weight of the safety rod 1 through elastic deformation, and prevent the increase in friction due to the increase in contact area. In a preferred embodiment, a plurality of pads 14 are provided along the axial direction of the safety rod 1. In other embodiments, the pad 14 can also be provided as a long strip structure provided along the axial direction of the safety rod 1.

[0056] In a further preferred embodiment, the pad 14 can be made of self-lubricating material to further reduce sliding friction, such as self-lubricating alloy containing graphite, etc. Correspondingly, the inclined wall surface 22 of the guide slideway is provided with a lubricating coating to reduce the sliding resistance of the safety rod 1.

[0057] In a preferred embodiment, the front end plug 11 of the safety rod 1 is connected to a driving device for driving the axial movement of the safety rod 1. In a further preferred embodiment, the driving device includes a passive driving mechanism and a locking mechanism. The locking state of the locking mechanism locks the safety rod 1 outside the reactor core, and the passive driving mechanism is in an energy storage state. When the locking mechanism is unlocked, the safety rod 1 is released and inserted into the reactor core under the action of the passive driving mechanism. The locking mechanism can use a mechanical locking pin, or an electromagnetic stop pin or claw.

[0058] In a further preferred embodiment, the passive driving mechanism may adopt a pressure accumulator spring. In other embodiments, the passive driving mechanism may also adopt a pneumatic or hydraulic pressure accumulator.

[0059] In a preferred embodiment, the rear end plug 12 of the safety rod 1 is provided with a conical guide section 16. When the safety rod 1 is driven to be inserted into the reactor core, the conical rear end plug 12 can play a guiding role to prevent the safety rod 1 from getting stuck due to centering errors.

[0060] In a preferred embodiment, a gas cavity spring (not shown) is further provided in the cladding 13, and the gas cavity spring is provided at one end of the neutron absorber 15. The gas cavity spring is in a compressed state to press the neutron absorber 15, thereby forming an axial limit for the neutron absorber 15. When the neutron absorber 15 undergoes axial size changes due to factors such as thermal deformation or irradiation growth, the gas cavity spring can absorb the axial deformation, thereby preventing the safety rod 1 from swelling and deforming under the high temperature irradiation condition of the reactor core.

[0061] In a preferred embodiment, the cladding 13 is welded to the front end plug 11 and the rear end plug 12 as a whole by TIG welding to seal the neutron absorber.

[0062] According to an embodiment of another aspect of the present invention, a solid-state core emergency shutdown method is provided.

[0063] The method adopts the solid-state core emergency shutdown device provided in the above-mentioned embodiment. The method is used to perform an emergency shutdown, including the following steps:

[0064] During the reactor assembly phase, the solid core active shutdown device is assembled, and a plurality of guide tubes 2 are installed into the solid core of the heat pipe micro-reactor so that the guide tubes 2 are distributed at intervals in the fuel assembly; the safety rod 1 is located outside the active area of ​​the reactor core, and the drive device is in a pressure storage state.

[0065] The shutdown control device of the solid core is connected to the drive device signal. The shutdown signal of the shutdown control device can be active, for example, actively sending a shutdown signal when the shutdown requirement is met; or it can be passive, for example, maintaining the shutdown signal under normal conditions and turning off the shutdown signal when the shutdown requirement is met.

[0066] After the shutdown control device sends a shutdown signal, the driving mechanism drives the safety rod 1 to be inserted into the reactor core along the guide slideway to realize shutdown. During the insertion process of the safety rod 1, the cladding 13 of the safety rod 1 does not directly contact the guide slideway, but slides in contact with the guide slideway through the pad 14, which effectively reduces the friction force of axial movement and ensures the response speed of the shutdown action.

[0067] The purpose of the above embodiments is to further explain the present invention in detail in conjunction with the accompanying drawings so that those skilled in the art can understand the technical concept of the present invention. Within the scope of the present invention, the optimization or equivalent replacement of the part structure or method steps involved, and the combination of implementation methods in different embodiments without conflict of structure and principle, all fall within the protection scope of the present invention.

Claims

1. A solid-state core emergency shutdown device, characterized in that: include: A safety rod comprises a cladding and a neutron absorber, wherein the neutron absorber is enclosed in the cladding, and a pad is provided on the lower surface of the cladding; the safety rod can slide axially into the reactor core; A guide cylinder, which is arranged in the reactor core and provides a guide slideway for the safety rod, wherein the guide slideway has a horizontally arranged bottom surface, and two sides of the bottom surface are connected to inclined sloping walls; a driving mechanism, providing axial drive for the safety rod, so that the safety rod can be inserted into or withdrawn from the reactor core; Wherein, the cushion block of the safety rod matches the inclined wall surface of the guide slideway, and the safety rod abuts against the inclined wall surface through the cushion block and is separated from the bottom surface.

2. The solid-state core emergency shutdown device according to claim 1, characterized in that: The safety rod further comprises an air cavity spring, wherein the air cavity spring is arranged at one end of the neutron absorber in the cladding, and the air cavity spring presses the neutron absorber tightly along the axial direction.

3. The solid-state core emergency shutdown device according to claim 1, characterized in that: The cross section of the guide slideway is arranged to be a regular hexagon.

4. The solid-state core emergency shutdown device according to claim 1 or 3, characterized in that: The inclined wall surface of the guide slideway is provided with a lubricating coating.

5. The solid-state core emergency shutdown device according to claim 1 or 3, characterized in that: The cushion block is made of elastic material.

6. The solid-state core emergency shutdown device according to claim 1, characterized in that: The end of the safety rod that first enters the reactor core when the safety rod moves axially is provided with a guide section, and the guide section is configured as a conical structure.

7. The solid-state core emergency shutdown device according to claim 1, characterized in that: The driving device comprises a passive driving mechanism and a locking mechanism. The locking mechanism axially locks the safety rod in a locked state. When the locking mechanism is unlocked, the passive driving mechanism drives the safety rod to be inserted into the reactor core.

8. The solid-state core emergency shutdown device according to claim 7, characterized in that: The passive driving mechanism is configured as a pressure accumulator spring.

9. The solid-state core emergency shutdown device according to claim 1, characterized in that: The shell of the safety rod is sealed by welding.

10. A solid-state core emergency shutdown method, characterized in that: A solid-state core emergency shutdown device according to any one of claims 1 to 9 is used, and comprises the following steps: Assembling the solid core emergency shutdown device and installing the guide cylinder into the reactor core; Connecting the shutdown control device of the solid-state core to the drive mechanism signal; When the shutdown control device sends a shutdown signal, the driving mechanism drives the safety rod to be inserted into the reactor core along the guide slide to realize shutdown.

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