Accident-resistant heat pipe micro-stack

Abstract

The accident-resistant heat pipe micro-reactor comprises a reactor core assembly and a heat exchanger which are arranged in a reactor shell, the reactor shell is provided with a waste heat removal system, a plurality of air inlets of the waste heat removal system are formed in the bottom of the reactor shell, and a plurality of air outlets of the waste heat removal system are formed in the top of the reactor shell. And under the accident condition, the air inlet and the air outlet are opened, so that external air enters the reactor shell to realize natural convection to take away heat generated by the reactor core assembly, overheating melting of the reactor core assembly is avoided, and the risk of leakage of radioactive substances is reduced.

Description

Technical Field

[0001] The invention belongs to the field of nuclear power, and in particular relates to an accident-resistant heat pipe micro-reactor. Background Art

[0002] The heat pipe micro-reactor is a new type of small reactor system, usually with an electric power of less than 10MWe. It has the characteristics of factory prefabrication, transportable device, self-adjusting operation, and rapid deployment. The design is greatly simplified, and the safety and flexibility are significantly improved. It is highly suitable for special application scenarios such as space, ocean, remote areas, and mobile power sources. As one of the main technical routes of micro-reactors, the heat pipe micro-reactor has the advantages of full static, passive, small size and weight, and adaptive heat transfer power. It has broad development prospects and has been highly valued in the nuclear power field in recent years. The core of the heat pipe micro-reactor is a fully solid-state design without a traditional liquid cooling circuit. It relies on heat pipes to bring out the heat generated by the core to achieve power generation. This also means that once a large number of heat pipe failures occur, the core lacks direct cooling means. Therefore, providing an accident-resistant heat pipe micro-reactor to ensure that the core does not melt in the event of extreme large-scale heat pipe failures is of great value for improving the safety of the heat pipe micro-reactor. Summary of the invention

[0003] The purpose of the present invention is to provide an accident-resistant heat pipe micro-reactor to reduce the risk of core melting after an accident occurs.

[0004] An embodiment of the present invention provides an accident-resistant heat pipe micro-reactor, comprising a core assembly and a heat exchanger, wherein the core assembly comprises a stack container, a fuel rod and a matrix, the core assembly is installed in a reactor shell, the core and the heat exchanger are connected by a heat pipe passing through the reactor shell, and the heat pipe is passed through the fuel assembly. The reactor shell is provided with a residual heat removal system, and the residual heat removal system comprises a plurality of air inlets and exhaust ports, the plurality of air inlets are arranged at the bottom of the reactor shell, and the plurality of exhaust ports are arranged at the top of the reactor shell.

[0005] When an accident occurs, the air inlet and outlet are opened, allowing air to enter from the bottom of the reactor shell and flow out from the top to form natural convection, thereby reducing the temperature inside the core assembly and avoiding core melting accidents.

[0006] Furthermore, in some embodiments, the air inlet and the air outlet include a gate and a control system, and the control system includes an active controller and a passive controller. The active controller can control the gate to actively open after receiving an opening instruction; the passive controller maintains the gate in a closed state under normal operating conditions, and loses the ability to maintain the gate closed after reaching a preset threshold state. The active controller can actively intervene in the heat dissipation of the core assembly to avoid the deterioration of the accident, and the passive controller can automatically intervene in the event of failure of the heat pipe micro-reactor itself and its supporting systems to avoid the deterioration of the accident.

[0007] Furthermore, in some embodiments, the passive controller is connected to the heat exchanger signal. Under normal working conditions, the heat exchanger sends a normally closed signal to the passive controller so that the passive controller maintains the gate closed. When the heat exchanger stops working or the working state is abnormal, the normally closed signal is interrupted and the passive controller reaches the threshold state.

[0008] Furthermore, in some embodiments, the passive controller is configured as a fixing made of a low melting point alloy, which maintains the gate closed at room temperature. When the temperature inside the reactor shell exceeds the melting point of the fixing, the fixing melts to open the gate.

[0009] Furthermore, in some embodiments, a plurality of metal heat dissipation ribs are provided on the outer surface of the stack container.

[0010] Furthermore, in some embodiments, the plurality of metal ribs extend along a line connecting the air inlet and the air outlet.

[0011] Furthermore, in some embodiments, a heat exchange fan is also provided at the air inlet and / or the air outlet.

[0012] Furthermore, in some embodiments, the heat exchanger further includes a heat exchanger waste heat removal system, which cools down the heat exchanger and the heat pipe when the heat exchanger waste heat removal system is started.

[0013] Furthermore, in some embodiments, the core assembly also includes an emergency shutdown system, which includes a shutdown control rod and a shutdown drum. The control systems of the shutdown control rod and the shutdown drum are independent of each other and can respectively perform emergency shutdown functions after an accident occurs.

[0014] Furthermore, in some embodiments, a thermal insulation shielding layer is provided in the inner layer of the reactor shell, a vacuum chamber is provided between the thermal insulation shielding layer and the core assembly, and the air inlet and the air outlet are connected to the vacuum chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of the radial cross-sectional structure of a heat pipe micro-reactor reactor shell and a core assembly in one embodiment;

[0016] Figure 2 It is a schematic diagram of the axial cross-section structure of the heat pipe micro-reactor reactor shell and the core assembly in one embodiment;

[0017] Figure 3 This is a schematic diagram of natural circulation heat dissipation of a heat pipe micro-stack in one embodiment;

[0018] Figure 4 This is a curve showing the maximum temperature change of the substrate after a heat pipe micro-reactor accident in one embodiment.

[0019] 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

[0020] The present invention is further described in detail below through specific embodiments.

[0021] 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.

[0022] 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, which 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.

[0023] 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.

[0024] 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.

[0025] As a new type of all-solid-state reactor, the heat pipe micro reactor has the advantages of small size, simple structure and high safety. Since it does not have a liquid cooling circuit, its basic structure is quite different from that of conventional pressurized water reactors. Figure 3 As shown, it includes a reactor shell 10 and a heat exchanger 40. The reactor shell 10 contains a reactor, which releases heat through nuclear reaction. The heat pipe 3 passes through the reactor shell 10 to transfer the heat in the reactor to the heat exchanger 40 to drive the power generation device to complete power generation. The internal structure of the reactor shell 10 is as shown in FIG. Figure 1 As shown, the reactor core assembly is arranged inside the reactor shell 10, and the core assembly is composed of a stack container 21, a neutron reflector 22, a drum 23, a fuel assembly 24, and a control rod channel 25 from the outside to the inside, and the heat pipe 3 is arranged in the matrix of the fuel assembly 24. A thermal insulation shielding layer 11 is arranged inside the reactor shell 10 to shield neutron radiation and reduce the heat loss of the core assembly to the outside. A vacuum chamber 14 is arranged between the thermal insulation shielding layer 11 and the stack container 21 to further reduce the heat loss of the core assembly and improve the power generation efficiency. Under normal working conditions, the nuclear fuel in the fuel assembly 24 fissions and releases heat, and the heat is transported to the heat exchanger 40 through the heat pipe 3 to generate electricity, so that the heat generation and heat dissipation in the core assembly are in a balanced state. When extreme accidents such as a large number of heat pipe failures occur, the core heat cannot be discharged through the heat pipes, and the fuel assembly 24 will overheat or even melt, resulting in the risk of leakage of radioactive products.

[0026] In order to solve the above problems, an embodiment of the present invention provides an accident-resistant heat pipe micro-rice, which is provided with an air inlet 12 and an air exhaust port 13 on the reactor shell 10, wherein three air inlets 12 are arranged at the bottom of the reactor shell 10, and three air exhaust ports 13 are arranged at the top of the reactor shell 10, which are respectively connected to the vacuum chamber 14. Once an accident occurs and the core assembly overheats, the air inlet 12 and the air exhaust port 13 are opened, allowing air to enter the vacuum chamber 14 from the air inlet 12 at the bottom of the reactor shell 10, take away the heat on the surface of the stack container 21, and then flow out from the air exhaust port 13 at the top to form natural convection, thereby quickly reducing the temperature of the core assembly. With the vacuum chamber 14 as the flow channel, the air inlet 12 and the air exhaust port 13 together constitute the waste heat removal system of the reactor shell 10. In a preferred embodiment, combined with Figure 3 The heat exchanger 40 is also provided with a heat exchanger waste heat removal system 41, which removes the heat transmitted by the heat pipe 3 through convection at one end of the heat exchanger 40, thereby assisting in reducing the temperature inside the core assembly.

[0027] However, under some accident conditions, the power supply and auxiliary power supply of the heat pipe micro-reactor itself may be interrupted, such as the failure of the heat exchanger 40 or the failure of heat transfer of most heat pipes 3. In such a case, it is difficult to achieve heat dissipation of the core assembly by active control. Therefore, in a preferred embodiment, the gates of the air inlet 12 and the air outlet 13 are provided with a control system, and the control system includes a set of active controllers and a set of passive controllers, wherein the active controller is used to open the gates of the air inlet 12 and the air outlet 13 in an active controlled manner under normal power supply conditions; and the passive controller maintains the gate in a normally closed state under normal reactor conditions, and when the preset threshold state is reached, the gate will lose the ability to maintain the gate closed and the gate will be passively opened.

[0028] In some embodiments, the gates of the air inlet 12 and the air outlet 13 are both configured as sealed gates that open downward, and the passive controller is configured as an electromagnetic control device that maintains the gate closed when powered on. The electromagnetic control device is powered by a heat exchanger. Once the heat exchanger fails and the electromagnetic control device loses power, the gate will automatically fall under the action of gravity to open the air inlet 12 and the air outlet 13 and start convective heat exchange.

[0029] In other embodiments, the passive controller is configured as a fixing made of a low-melting-point alloy, which is used to fix the gates of the air inlet 12 and the exhaust port 13 on the reactor shell 10. Once the core assembly is overheated, the temperature in the vacuum chamber 14 exceeds the melting point of the fixing, the fixing melts and fails, causing the gate to fall off the reactor shell 10 under the action of gravity, so that the air inlet 12 and the exhaust port 13 are passively opened to start convective heat exchange.

[0030] In a preferred embodiment, if Figure 2 As shown, a plurality of metal heat dissipation ribs 27 are protruding from the surface of the stack container 21 to increase the heat exchange area of ​​the stack container 21 and improve the heat dissipation efficiency. In a further preferred embodiment, the extension direction of the metal heat dissipation ribs 27 is consistent with the direction of the line connecting the air inlet 12 and the air outlet 13 to improve the air flow efficiency. In other embodiments, a partition 26 is also provided on the surface of the stack container 21 to divide the vacuum chamber 14 into a plurality of flow channels, and each flow channel has an air outlet 13 and an air inlet 12 at the upper and lower ends to increase the air flow rate in the flow channel.

[0031] In some embodiments, the air inlet 12 and the air outlet 13 may also be provided with a heat exchange fan, which can further increase the air flow rate and improve the heat dissipation effect.

[0032] In a preferred embodiment, the drum 23 and the shutdown control rods in the core assembly use independent control systems respectively, and the emergency shutdown function of the reactor can be achieved by rotating the drum 23 alone or inserting the shutdown control rods into the control rod channel 25.

[0033] With Figures 1 to 3 The heat pipe micro-reactor of the structure shown is provided with two sets of independently controlled emergency shutdown systems in the core assembly, which can ensure timely shutdown after an accident occurs; two sets of independent residual heat removal systems with convection heat dissipation function are respectively provided at both ends of the reactor shell 10 and the heat exchanger 40. After an accident occurs, no matter whether the heat pipe 3 and the heat exchanger 40 fail or not, and whether the external energy is lost or not, the residual heat in the core assembly can be effectively discharged to avoid overheating and melting of the core. In one embodiment, the matrix temperature change curve of the fuel assembly 24 in the case of complete failure of the heat pipe 3 after emergency shutdown under simulated accident conditions is as follows Figure 4 As shown, the substrate temperature never exceeds the allowable temperature of 800°C, the structural safety of the heat pipe micro-reactor is effectively guaranteed, and there will be no accidents of radioactive material leakage.

[0034] 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 involved and the combination of the implementation methods in different embodiments without conflict of structure and principle all fall within the protection scope of the present invention.

Claims

1. An accident-resistant heat pipe micro-reactor, comprising a core assembly and a heat exchanger, wherein the core assembly comprises a stack container and a fuel assembly, the core assembly is installed in a reactor shell, the core assembly and the heat exchanger are connected via a heat pipe passing through the reactor shell, the heat pipe is arranged in the fuel assembly, and is characterized in that: The reactor shell is provided with a waste heat removal system, which includes a plurality of air inlets and air outlets. The plurality of air inlets are arranged at the bottom of the reactor shell, and the plurality of air outlets are arranged at the top of the reactor shell.

2. The accident-resistant heat pipe micro-reactor according to claim 1, characterized in that: The air inlet and the air outlet include a gate and a control system. The control system includes an active controller and a passive controller. The active controller can control the gate to actively open after receiving an opening instruction; the passive controller maintains the gate in a closed state under normal working conditions, and loses the ability to maintain the gate closed after reaching a preset threshold state.

3. The accident-resistant heat pipe micro-reactor according to claim 2, characterized in that: The passive controller is connected to the heat exchanger signal. Under normal working conditions, the heat exchanger sends a normally closed signal to the passive controller so that the passive controller maintains the gate closed. When the heat exchanger stops working or the working state is abnormal, the normally closed signal is interrupted and the passive controller reaches the threshold state.

4. The accident-resistant heat pipe micro-reactor according to claim 2, characterized in that: The passive controller is configured as a fixing made of a low melting point alloy, which maintains the gate closed at room temperature. When the temperature inside the reactor shell exceeds the melting point of the fixing, the fixing melts to open the gate.

5. The accident-resistant heat pipe micro-reactor according to any one of claims 1 to 4, characterized in that: The outer surface of the stack container is provided with a plurality of metal heat dissipation ribs.

6. The accident-resistant heat pipe micro-reactor according to claim 5, characterized in that: The plurality of metal ribs extend along a line connecting the air inlet and the air outlet.

7. The accident-resistant heat pipe micro-reactor according to any one of claims 1 to 4, characterized in that: A heat exchange fan is also provided at the air inlet and / or the air outlet.

8. The accident-resistant heat pipe micro-reactor according to any one of claims 1 to 4, characterized in that: The heat exchanger further comprises a heat exchanger waste heat removal system, which cools down the heat exchanger and the heat pipe when the heat exchanger waste heat removal system is started.

9. The accident-resistant heat pipe micro-reactor according to any one of claims 1 to 4, characterized in that: The core assembly also includes an emergency shutdown system, which includes a shutdown control rod and a shutdown drum. The control systems of the shutdown control rod and the shutdown drum are independent of each other and can respectively perform emergency shutdown functions after an accident occurs.

10. The accident-resistant heat pipe micro-reactor according to any one of claims 1 to 4, characterized in that: The inner layer of the reactor shell is provided with a heat-insulating shielding layer, a vacuum chamber is provided between the heat-insulating shielding layer and the core assembly, and the air inlet and the air outlet are connected to the vacuum chamber.

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