High-temperature gas cooled reactor cooling system and cooling method after emergency shutdown of high-temperature gas cooled reactor

Abstract

The invention relates to the technical field of high-temperature gas cooled reactor primary loop cooling, in particular to a high-temperature gas cooled reactor cooling system and a cooling method after emergency shutdown of a high-temperature gas cooled reactor. The high-temperature gas cooled reactor cooling system comprises a reactor body communicated with a steam generator, the steam generator is circularly communicated with a helium supply and discharge pipeline, the two ends of the helium supply and discharge pipeline are both communicated with a cooling connector of the steam generator, and the helium supply and discharge pipeline is communicated with a first helium storage part and a second helium storage part in parallel; one end of the first cooling pipeline is communicated with the helium supply and discharge pipeline between the first helium storage part and the steam generator, the other end of the first cooling pipeline is communicated with the absorption ball subsystem, and the absorption ball subsystem is communicated with the top of the reactor body. Different modes such as depressurization circulation, pressurization circulation and top direct cooling are selectively started according to the actual temperature condition of the upper area of the reactor core, and the system safety of the high-temperature gas cooled reactor in the emergency shutdown process is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high temperature gas cooled reactor primary loop cooling, in particular to a high temperature gas cooled reactor cooling system and a high temperature gas cooled reactor post-emergency shutdown cooling method. BACKGROUND

[0002] The primary loop of the high temperature gas cooled reactor uses helium as the coolant. After the reactor is shut down, the core is still at a high temperature due to residual heat, while the coolant in the primary loop is relatively low in temperature at parts such as the steam generator. According to the principle of thermal expansion and contraction, the helium in the core expands and its density decreases, while the relatively cold helium in the primary loop has a higher density. This density difference causes the helium to naturally form a circulating flow, i.e. the relatively hot helium rises from the core, flows to the steam generator and other cooling components through the hot gas duct, and after being cooled, its density increases and it then descends along the primary loop back to the core, thereby forming a natural circulation.

[0003] The reactor in-vessel metal in-vessel components mainly consist of a core shell, an upper support plate, a lower support plate, a positioning plate, a pressing plate and the like. The natural circulation phenomenon after the reactor is shut down can cause the temperature of the upper part of the core to rise and the temperature of the lower part of the core to decrease. The upper metal components such as the positioning plate and the support plate are challenged by high temperature. In particular, the high temperature gas cooled reactor absorbing ball level gauge is located at the upper part of the support plate and has a high temperature requirement for the working environment, and lacks conditions for online maintenance and replacement, resulting in a high safety risk during the emergency shutdown of the high temperature gas cooled reactor. SUMMARY

[0004] The present application provides a high temperature gas cooled reactor cooling system and a high temperature gas cooled reactor post-emergency shutdown cooling method to solve the problem in the prior art that the temperature of the upper part of the reactor in the high temperature gas cooled reactor rises to exceed the upper temperature limit of the temperature-resistant equipment in the reactor after the reactor is shut down, resulting in a high safety risk during the emergency shutdown of the high temperature gas cooled reactor.

[0005] In a first aspect, the present application provides a high temperature gas cooled reactor cooling system, comprising: a reactor body, which is in communication with a steam generator, a helium supply and discharge pipeline is in circulation communication with the steam generator, both ends of the helium supply and discharge pipeline are in communication with a cooling interface of the steam generator, a first helium storage component and a second helium storage component are in parallel communication with the helium supply and discharge pipeline, the helium pressure in the first helium storage component is greater than the primary loop helium pressure, and the helium pressure in the second helium storage component is less than the primary loop helium pressure; a first cooling pipeline, one end of which is in communication with the helium supply and discharge pipeline between the first helium storage component and the steam generator, and the other end of which is in communication with an absorbing ball subsystem, the absorbing ball subsystem is in communication with the top of the reactor body.

[0006] After the reactor emergency shutdown, the helium supply and exhaust pipeline is communicated with the first helium storage and the second helium storage, first the helium at the bottom of the reactor body is discharged to the second helium storage through the cooling interface to reduce the helium pressure in the primary loop to achieve a small flow of helium pressure reduction cycle, and the purpose of reducing the temperature of the core upper chamber of the reactor body is achieved. When the core top chamber temperature is still high and the increasing trend does not change during the reactor pressure reduction process, the first helium storage is used to supply gas through the small flow cooling interface to realize the pressurization cycle for cooling. When the temperature near the core top chamber of the reactor body approaches the metal temperature limit, the gas is taken from the cooling interface communicated with the output end of the first helium storage, and is sent to the core top cavity of the core top chamber through the absorber ball subsystem for direct cooling. By communicating the first helium storage and the second pressure storage with the inner cavity of the reactor body through the steam generator, the pressure difference between the first helium storage and the second pressure storage and the helium pressure in the primary loop can be used to spontaneously drive the primary loop helium to form a small flow cycle after the reactor body emergency shutdown, and the initial cooling of the passive or low-active start is realized. At the same time, in order to ensure the effectiveness of the cooling system, the absorber ball subsystem is used to directly deliver cooling helium to the core top, which can control the temperature rise of the upper part of the core and ensure the safe operation of the key equipment at the top of the reactor body. By selectively enabling the pressure reduction cycle, the pressurization cycle and the top direct cooling and other different modes, the temperature of the upper part of the core of the reactor body is controlled, so that the core temperature of the high temperature gas cooled reactor is solved after the emergency shutdown, and the core temperature of the high temperature gas cooled reactor is ensured during the emergency shutdown process.

[0007] In an alternative embodiment, a second cooling pipeline is further included, one end of which is communicated with the first cooling pipeline, and the other end of which is communicated with a fuel handling subsystem, and the fuel handling subsystem is communicated with the top of the reactor body.

[0008] When the cooling effect of the first cooling pipeline and the absorber ball subsystem is insufficient, the second cooling pipeline can be enabled to guide part of the helium from the first cooling pipeline to the fuel handling subsystem, and finally the helium is delivered to the top of the reactor body by the fuel handling subsystem for blowing cooling. By introducing the fuel handling subsystem as an additional cooling path, a larger flow and higher cooling intensity final guarantee means is provided, which can effectively and quickly curb the temperature rising trend when the temperature of the core top cavity continues to rise rapidly, and the reliability and redundancy backup capability of the entire cooling system are enhanced.

[0009] In an alternative embodiment, a helium compressor is installed on the first cooling pipeline, and the second cooling pipeline is communicated downstream of the helium compressor.

[0010] The helium compressor installed on the first cooling pipeline can pressurize the helium flowing through the first cooling pipeline, and then the pressurized helium can be distributed to the absorption ball subsystem or the second cooling pipeline connected downstream of the helium compressor as needed, thereby providing sufficient conveying power for the helium flowing to the top of the reactor body. The helium compressor pressurizes and conveys the helium in the first cooling pipeline and the second cooling pipeline, ensuring that the helium can be effectively conveyed to the top cavity of the reactor core.

[0011] In an alternative embodiment, a regulating valve is installed on the absorption ball subsystem, which is used to control the flow of helium flowing to the reactor body through the absorption ball subsystem.

[0012] The flow of cooling helium flowing to the reactor body through the absorption ball subsystem can be adjusted according to the actual temperature rise of the top cavity of the reactor core, thereby ensuring effective cooling while avoiding excessive or rapid cooling that can cause the temperature of the top cavity of the reactor core to fluctuate dramatically, and avoiding unnecessary thermal stress or reactivity disturbance to the internal components of the reactor body.

[0013] In an alternative embodiment, the absorption ball subsystem is installed with multiple groups. According to the change trend of the temperature of the top cavity of the reactor core, one or more groups of the multiple groups of absorption ball subsystems can be selectively activated to deliver cooling helium to the top of the reactor body through the selected absorption ball subsystem.

[0014] In an alternative embodiment, a temperature monitoring device is installed in the reactor body, arranged near the top of the reactor body.

[0015] The temperature monitoring device is used to monitor the temperature change of the top cavity of the reactor core in real time and transmit the temperature signal to the control system. It provides data support for the selection of cooling strategy and the adjustment of cooling helium flow, ensuring that the corresponding cooling measures can be activated in time when the temperature of the top cavity of the reactor core changes, and improving the initiative and safety of the micro-flow cooling control.

[0016] In a second aspect, the present application also provides a high-temperature gas-cooled reactor emergency shutdown cooling method, comprising the following steps: The reactor body is shut down, and the main helium blower stops running. Helium is discharged from the second helium storage device through the cooling interface of the steam generator to reduce the pressure of the primary helium circuit; During the process of reducing the pressure of the primary helium circuit, if the temperature of the top cavity of the reactor body is not lower than the preset temperature value and the temperature increase trend is not less than the preset temperature increase value, the first helium storage device supplies helium to the primary helium circuit through another cooling interface of the steam generator to increase the pressure of the primary helium circuit. When the temperature of the top chamber of the reactor body exceeds the temperature threshold, part of the helium gas discharged by the first helium storage member is introduced into the top chamber of the reactor body through the first cooling pipeline and the absorption ball subsystem.

[0017] After the reactor is shut down, an initial helium pressure reduction cycle is first established by a pressure relief operation to suppress temperature rise; when it is monitored that the temperature control effect of the top chamber does not meet the preset condition, a pressurization cycle mode is switched to enhance cooling; if the temperature of the top chamber of the reactor body further rises and exceeds the temperature threshold, direct purge cooling through the absorption ball subsystem is started to specifically dissipate heat in the top high-temperature area. Through automatic switching between the pressure reduction cycle and the pressurization cycle modes according to the temperature, preliminary cooling of the upper part of the reactor core can be achieved without additional power equipment; when the temperature exceeds the threshold, the absorption ball subsystem directly delivers cooling helium gas to the top chamber of the reactor body to cool the key area of the upper part of the reactor core, effectively control the temperature rise of the upper cavity of the reactor core, and ensure the safe operation of the key equipment such as the absorption ball level meter located at the top of the reactor body.

[0018] In an optional embodiment, the method further comprises: Part of the helium gas passing through the first cooling pipeline enters the second cooling pipeline and is introduced into the top chamber of the reactor body through the fuel handling subsystem.

[0019] When the cooling effect through the first cooling pipeline is still insufficient to control the temperature, part of the helium gas flowing through the first cooling pipeline is guided to the second cooling pipeline and directly introduced into the top chamber of the reactor body through the fuel handling subsystem for strong purge cooling. The emergency cooling means with stronger cooling capacity and larger cooling flow rate can achieve rapid and efficient temperature suppression in the extreme condition of continuous and rapid temperature rise in the top chamber of the reactor core, thereby providing the highest level of redundant protection for the safety of the reactor.

[0020] In an optional embodiment, in the step of reducing the pressure of the primary loop helium gas, the pressure of the primary loop helium gas is not less than the required pressure of the primary loop during startup of the reactor body.

[0021] The lower pressure limit constraint ensures that a necessary safety pressure difference can be maintained between the primary loop and the secondary loop, effectively preventing the risk of failure of the pressure boundary of the steam generator due to too low pressure of the primary loop during cooling, thereby ensuring the safety of the equipment on the secondary loop side while cooling by pressure relief.

[0022] In an optional embodiment, in the step of increasing the pressure of the primary loop helium gas, the pressure of the primary loop helium gas is not greater than the maintained pressure of the primary loop during normal operation of the reactor body.

[0023] The upper pressure limit constraint can prevent the primary loop system and related pressure-bearing equipment from overpressure during the pressurized cooling process, avoid equipment damage or safety risks caused by pressure exceeding the design reference, and ensure that the entire pressurized cooling operation is safely and reliably performed within the pressure-bearing safety boundary of the original system design. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings required to be used in the specific embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0025] Figure 1 A structural schematic diagram of a high-temperature gas cooled reactor cooling system is provided for the embodiments of the present application.

[0026] The reference signs are explained as follows: 1, reactor body; 2, steam generator; 3, helium storage tank; 4, absorbing ball subsystem; 5, fuel loading and unloading subsystem; 6, helium compressor; 7, helium supply and discharge pipeline; 8, first cooling pipeline; 9, second cooling pipeline; 10, temperature monitoring member; 11, absorbing ball level meter. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0028] The embodiments of the present application will be described below in combination with Figure 1 .

[0029] According to the embodiments of the present application, on the one hand, a high-temperature gas cooled reactor cooling system is provided, mainly including a reactor body 1, a steam generator 2, a helium supply and discharge pipeline 7, a first helium storage member, a second helium storage member, a first cooling pipeline 8, and an absorbing ball subsystem 4 and other components.

[0030] The reactor body 1 is in communication with the steam generator 2, the reactor body 1 is used for the helium gas heated by being passed in, the high-temperature helium gas after being heated enters the high-temperature side of the steam generator 2 and exchanges heat with the water in the low-temperature side of the steam generator 2 to generate high-temperature steam. The high-temperature side chamber for circulating helium gas arranged outside the steam generator 2 is circularly communicated with the helium gas supply and discharge pipeline 7, and both ends of the helium gas supply and discharge pipeline 7 are communicated with the cooling interfaces of the steam generator 2. Specifically, the gas supply end of the helium gas supply and discharge pipeline 7 is communicated with the cooling interface at the top of the steam generator 2, and the gas discharge end of the helium gas supply and discharge pipeline 7 is communicated with the cooling interface at the bottom of the steam generator 2.

[0031] The first helium storage part and the second helium storage part are communicated on the helium gas supply and discharge pipeline 7, the pressure of the helium gas stored in the first helium storage part is greater than the pressure of the one-loop helium gas, and the pressure of the helium gas stored in the second helium storage part is less than the pressure of the one-loop helium gas. The first helium storage part and the second helium storage part are only distinguished by the internal pressure, during the operation of the high-temperature gas cooled reactor cooling system, the pressure of the one-loop helium gas and the pressure in the first helium storage part and the second helium storage part are constantly changing, so the first helium storage part and the second helium storage part can be converted with each other, when the pressure in the first helium storage part is lower than the pressure of the one-loop helium gas, the first helium storage part is converted to be used as the second helium storage part, and when the pressure in the second helium storage part is higher than the pressure of the one-loop helium gas, the second helium storage part is converted to be used as the first helium storage part. In the embodiment, the first helium storage part and the second helium storage part are both selected to be helium storage tanks 3, Figure 1 In the embodiment, only one group of helium storage tanks 3 is shown by omitting the drawing.

[0032] One end of the first cooling pipeline 8 is communicated with the helium gas supply and discharge pipeline 7 between the first helium storage part and the steam generator 2, the other end of the first cooling pipeline 8 is communicated with the absorption ball subsystem 4, and the absorption ball subsystem 4 is further communicated with the top of the reactor body 1.

[0033] After the reactor is shut down, the steam generator 2 stops operating, and the steam generator 2 is communicated with the first helium storage part and the second helium storage part through the helium gas supply and discharge pipeline 7. First, the helium gas at the bottom of the reactor body 1 is discharged to the inside of the second helium storage part through the cooling interface, the one-loop helium gas pressure is reduced to realize the micro-flow circulation of the helium gas, so as to reduce the temperature of the upper chamber of the reactor core of the reactor body 1. When the temperature of the upper chamber of the reactor core is still high and the temperature increasing trend does not change during the reactor depressurization process, the first helium storage part is used to supply helium gas to the one-loop through the micro-flow cooling interface, so as to realize the pressurization circulation for cooling. When the temperature near the upper chamber of the reactor core of the reactor body 1 approaches the metal temperature limit value, the gas is taken from the cooling interface communicated with the output end of the first helium storage part, is transported to the absorption ball subsystem 4 through the first cooling pipeline 8, and then is supplied to the upper cavity of the reactor core of the upper chamber of the reactor core, so as to perform direct cooling.

[0034] Through the technical scheme, the first helium storage element and the second helium storage element of different pressure grades are connected with the inner cavity of the reactor body 1 through the steam generator 2, the pressure difference between the first helium storage element, the second helium storage element and the helium gas in the primary loop can be used to drive the primary loop helium to form a small flow circulation spontaneously after the reactor body 1 is shut down, and the preliminary cooling of the non-active or low-active start is realized. At the same time, in order to ensure the effectiveness of the cooling system, the cooling helium is directly delivered to the top of the core by using the absorbing ball subsystem 4, the temperature rising amplitude of the upper part of the core can be effectively controlled, and the safe operation of the key equipment at the top of the reactor body 1 is ensured. By selectively enabling different cooling modes such as pressure reduction circulation, pressure increase circulation and top direct cooling, the temperature of the upper part of the core of the reactor body 1 is controlled, so that the core problem of the over-temperature of the key area of the upper part of the core of the high-temperature gas cooled reactor after the emergency shutdown is solved without relying on the steam generator 2 and the secondary loop system, and the system safety of the high-temperature gas cooled reactor in the emergency shutdown process is ensured.

[0035] In one embodiment, the high-temperature gas cooled reactor cooling system is further provided with a second cooling pipeline 9, one end of the second cooling pipeline 9 is connected with the first cooling pipeline 8, and the other end is connected with the fuel loading and unloading subsystem 5, and the fuel loading and unloading subsystem 5 is further connected with the top of the reactor body 1.

[0036] When the cooling effect of the cooling path composed of the first cooling pipeline 8 and the absorbing ball subsystem 4 on the core top cavity is insufficient, and the trend of continuous temperature rise of the core top cavity cannot be effectively curbed, the second cooling pipeline 9 can be immediately enabled to guide part of the helium gas from the first cooling pipeline 8 to the fuel loading and unloading subsystem 5, and finally the helium gas is delivered to the top of the reactor body 1 by the fuel loading and unloading subsystem 5 to directly blow and cool the core top cavity, and the helium gas flow can be flexibly adjusted through the gas supply valve on the fuel loading and unloading subsystem 5. By introducing the fuel loading and unloading subsystem 5 as an additional cooling path, a final guarantee means with larger flow and higher cooling strength is provided, which can effectively and quickly curb the temperature rising trend when the temperature of the core top cavity continues to rise rapidly, and the reliability and redundancy backup capability of the entire cooling system are enhanced, and the safe operation of the absorbing ball level meter 11 and other key equipment at the top of the reactor body 1 can still be effectively protected under the most severe working conditions.

[0037] Further, the helium compressor 6 is installed on the first cooling pipeline 8, and the second cooling pipeline 9 is connected at a downstream position of the helium compressor 6. The helium compressor 6 installed on the first cooling pipeline 8 can pressurize the helium flowing through the first cooling pipeline 8, so that the pressure of the helium is raised to a level sufficient to overcome the flow resistance of the system. Then, the pressurized helium can be flexibly distributed to the absorber ball subsystem 4 or the second cooling pipeline 9 connected downstream of the helium compressor 6 according to actual cooling requirements, thereby providing sufficient conveying power for the helium flowing to the top of the reactor body 1.

[0038] The helium compressor 6 pressurizes and conveys the helium in the first cooling pipeline 8 and the second cooling pipeline 9, ensuring that the helium can overcome the flow resistance in the absorber ball subsystem 4 or the fuel handling subsystem 5 and be stably and effectively conveyed to the top cavity of the reactor core, thereby achieving reliable cooling effect. By centrally arranging the helium compressor 6 on the first cooling pipeline 8, the cooling helium is uniformly pressurized, avoiding repeated arrangement of pressurizing equipment on the second cooling pipeline 9, simplifying the system structure, improving the equipment utilization rate of the helium compressor 6, and reducing the system construction and maintenance costs.

[0039] As an alternative embodiment, independent helium compressors 6 can also be installed on the first cooling pipeline 8 and the second cooling pipeline 9 respectively, to realize completely independent operation of the two cooling paths, further improving the redundancy and operation flexibility of the system, or a distribution valve is arranged at the outlet of the helium compressor 6 to accurately control the proportion of helium flowing to the absorber ball subsystem 4 and the fuel handling subsystem 5.

[0040] In one embodiment, an adjusting valve is installed on the absorber ball subsystem 4, which is used to control the flow of helium flowing through the absorber ball subsystem 4 to the reactor body 1. The adjusting valve on the absorber ball subsystem 4 can adjust the flow of cooling helium flowing through the absorber ball subsystem 4 to the reactor body 1 by adjusting the valve opening according to the actual temperature rise of the top cavity of the reactor core, so as to avoid excessive or rapid cooling that may cause the temperature of the top cavity of the reactor core to fluctuate sharply and cause unnecessary thermal stress or reactivity disturbance to the internal components of the reactor body 1, while ensuring effective cooling.

[0041] Through fine control of the adjusting valve, stepless adjustment of the flow of cooling helium can be realized, and the cooling intensity can be dynamically adjusted according to the rate of temperature change, so that the temperature of the top cavity of the reactor core decreases in a gentle curve, ensuring the cooling effect and maintaining the thermal hydraulic stability of the internal components of the reactor body 1.

[0042] The adjusting valve can be a pneumatic adjusting valve, an electric adjusting valve or a hydraulic adjusting valve, or can be in the form of a combination of a stop valve and a flowmeter, which is adjusted by manual or automatic means.

[0043] In one embodiment, the absorption ball subsystem 4 is installed in multiple groups, and each group of the absorption ball subsystem 4 is connected with the first cooling pipeline 8. The absorption ball subsystem 4 is installed in multiple groups, and each group of the absorption ball subsystem 4 is connected with the first cooling pipeline 8. According to the change trend of the temperature of the upper cavity of the reactor core, one or more groups of the absorption ball subsystem 4 can be selectively started, and the selected absorption ball subsystem 4 is used to deliver the cooling helium to the top of the reactor body 1.

[0044] The multiple groups of the absorption ball subsystem 4 provide a modular cooling capacity configuration. Different numbers of groups of the absorption ball subsystem 4 can be selectively started according to the severity of the temperature rise of the upper cavity of the reactor core, so that the cooling capacity is adjusted in stages, and the adaptability and control flexibility of the system to different temperature rise conditions are enhanced.

[0045] In one embodiment, the temperature monitoring member 10 is installed in the reactor body 1 and arranged near the top of the reactor body 1. The temperature monitoring member 10 is used to monitor the temperature change of the upper cavity region of the reactor core in real time and transmit the temperature signal to the control system, so as to provide data support for the selection of the cooling strategy and the adjustment of the flow of the cooling helium, and ensure that the corresponding cooling measures can be started in time when the temperature of the upper cavity of the reactor core changes, thereby improving the initiative and safety of the micro-flow cooling control.

[0046] The temperature monitoring member 10 usually adopts a sheathed thermocouple and is installed near the top support plate or the side wall of the upper cavity of the reactor core top head at the top of the reactor body 1. The temperature monitoring member 10 can reflect the actual temperature of the upper metal component of the reactor core, and the monitoring signal is transmitted to the reactor protection system or a special safety facility system through a high-temperature resistant cable or a wireless manner, so as to serve as an automatic starting signal for triggering different levels of cooling measures.

[0047] The temperature monitoring member 10 can be arranged in multiple points. Multiple temperature measuring points are installed at different heights and directions of the upper cavity of the reactor body 1 to form a temperature field monitoring network, so as to comprehensively grasp the temperature distribution of the upper part of the reactor core.

[0048] According to the embodiment of the present application, another aspect further provides a high-temperature gas cooled reactor post-emergency shutdown cooling method, which comprises the following steps: In the first step, after the reactor body 1 is subjected to an emergency shutdown and the main helium blower is stopped, the helium in the primary loop system is actively discharged into the second helium storage member through the cooling interface arranged on the steam generator 2, a differential pressure driven natural circulation is formed by reducing the pressure of the helium in the primary loop, and the circulation flow of the helium is reduced, so as to take away part of the residual heat of the upper part of the reactor core.

[0049] Secondly, during the process of continuously reducing the pressure of the primary loop, the temperature change of the top chamber of the reactor body 1 is monitored in real time. If the actual temperature of the top chamber of the reactor body 1 is not lower than the preset temperature preset value, and the temperature increasing trend, i.e. the temperature rising rate, is not less than the preset temperature increasing preset value, it indicates that the cooling effect of the pressure reduction cycle is insufficient, and the cooling mode is switched immediately. High-pressure helium gas is supplied to the primary loop in reverse through another cooling interface of the steam generator 2 by the first helium storage device, so that the pressure of the primary loop helium gradually rises, and a pressurization cycle cooling mode is formed.

[0050] Thirdly, during the pressurization cycle cooling process, the temperature of the top chamber of the reactor body 1 is continuously monitored. If the temperature of the top chamber of the reactor body 1 further rises and exceeds the set temperature threshold value, it indicates that the upper part of the core has faced the risk of over-temperature, and the first cooling pipeline 8 is immediately started to deliver part of the high-pressure helium gas discharged by the first helium storage device to the absorber ball subsystem 4, and finally directly into the top chamber of the reactor body 1 through the absorber ball subsystem 4, to implement direct purging and cooling of the upper part of the core region.

[0051] Among them, the second helium storage device can be arranged in the form of multiple low-pressure helium storage tanks 3 in series to gradually reduce the pressure of the primary loop, or a pressure regulating valve can be arranged to control the helium discharge rate; the temperature preset value and the temperature increasing preset value can be flexibly set between 200°C and 400°C and between 5°C / min and 20°C / min according to the design parameters of different reactors; the temperature threshold value is usually set within a safety margin range of 50°C to 100°C below the metal component temperature limit value 500°C, and the specific value can be adjusted according to the temperature resistance requirement of the absorber ball level meter 11.

[0052] By correlating and logically judging the three modes of pressure reduction cycle, pressurization cycle and top direct cooling with the real-time thermal parameters such as the absolute temperature value and temperature rising trend of the top chamber of the reactor, an adaptive and progressive residual heat removal strategy is constructed. In the extreme working condition of main helium fan stop and secondary loop isolation, the inherent pressure difference and existing equipment of the system are fully utilized, and the strength and mode of the cooling mechanism are dynamically and orderly adjusted according to the real thermal state of the upper part of the core region. The hierarchical cooling control not only can effectively limit the temperature rising amplitude of the upper part of the core cavity, and ensure that the key equipment such as the absorber ball level meter 11 installed at the top of the reactor body 1 is in a safe working environment, but also the starting and switching of the whole process rely on the existing physical conditions and monitoring signals, without introducing large active equipment, which can greatly improve the inherent safety and operation reliability of the reactor in accident conditions.

[0053] Further, when the effect of delivering cooling helium through the first cooling pipeline 8 is still insufficient to effectively control the temperature of the top cavity of the core, part of the helium flowing through the first cooling pipeline 8 is actively guided to the second cooling pipeline 9 and directly introduced into the top chamber of the reactor body 1 through the fuel handling subsystem 5 for strong forced sweeping and cooling. The flow of helium can be flexibly adjusted through the gas supply valve provided on the fuel handling subsystem 5.

[0054] By providing an emergency cooling means with stronger cooling capacity and larger cooling flow, rapid and strong temperature containment can be achieved in extreme working conditions where the temperature of the top cavity of the core continues to rise rapidly, thereby providing the highest level of redundant protection for reactor safety. Specifically, the ball inlet pipeline of the fuel handling subsystem 5 generally has a large flow capacity and can deliver a large amount of cooling helium to the top of the core in a short time, rapidly removing the accumulated heat.

[0055] In one embodiment, in the step of reducing the primary helium pressure, the minimum value of the reduced primary helium pressure is not less than the required primary pressure during the start-up of the reactor body 1. Specifically, the primary helium pressure cannot be lower than 4 MPa. This lower limit of the pressure constraint can ensure that the necessary safety pressure difference between the primary circuit and the secondary circuit can be maintained, effectively preventing the risk of imbalance of the pressure difference on both sides of the pressure boundary of the steam generator due to the excessively low primary pressure during the cooling process. In the design of a high-temperature gas-cooled reactor, the heat transfer tubes of the steam generator bear the primary helium pressure and the secondary water vapor pressure on both sides, respectively, and a reasonable pressure difference range must be maintained to prevent the heat transfer tubes from creeping deformation or mechanical damage. By setting a lower limit of the pressure in the step of reducing the primary helium pressure, the safety of the equipment on the secondary circuit side can be ensured while cooling by pressure relief, and the structural integrity of the steam generator is not damaged.

[0056] The lower limit of the pressure can be flexibly set in the range of 3.5 MPa to 4.5 MPa according to the design parameters of different reactor types, or a dynamic pressure limiting strategy can be adopted to calculate the minimum allowed primary pressure in real time according to the actual pressure of the secondary circuit, or a pressure protection valve can be set to automatically close the pressure relief pipeline when the primary pressure approaches the lower limit, preventing the pressure from continuing to drop.

[0057] Further, in the step of increasing the primary helium pressure, the maximum value of the primary helium pressure increase is not greater than the primary loop maintenance pressure during normal operation of the reactor body 1, specifically, the primary helium pressure increase cannot exceed 7 MPa. This upper pressure limit constraint can effectively prevent the primary loop system and related pressure-bearing equipment from being in an overpressure condition during the pressurized cooling process, avoiding equipment damage or safety risks due to pressure exceeding the design reference. The primary loop pressure boundary includes the reactor pressure vessel, steam generator, hot gas duct, main helium blower housing, and other key equipment, and the design pressure-bearing capacity of these equipment has a clear limit. Overpressure operation can lead to sealing failure, material damage, and even rupture of the equipment, and other serious accidents. By setting the upper pressure limit, the entire pressurized cooling operation can be safely and reliably performed within the original design pressure-bearing safety boundary of the system, protecting the structural integrity of the primary loop pressure-bearing equipment.

[0058] The pressure upper limit value can be fine-tuned within the range of 6.8 MPa to 7.2 MPa according to the actual operation life and material aging conditions, or multiple pressure protection barriers can be set, including a high-pressure automatic isolation valve and a safety valve, which automatically cut off the gas supply from the first helium storage component when the pressure approaches the upper limit, and open the safety valve to release pressure if necessary, or a staged pressurization strategy can be used, first increasing the pressure to an intermediate value to observe the temperature response, and then gradually increasing the pressure to approach the upper limit value as needed, avoiding the impact of one-time pressurization.

[0059] In summary, the high-temperature gas cooled reactor cooling system provided in the application stops the main helium blower after the reactor is tripped, the blower baffle is closed, the main feedwater and main steam on the secondary loop side are isolated, and the circulation of the primary loop and the secondary loop is stopped. At this time, under the action of the natural circulation of helium in the core, the temperature of the upper part of the core gradually increases, and the temperature of the lower part gradually decreases. About 10 hours later, the temperature reaches the highest point, and then slowly decreases. During normal operation, the reactor operates at a pressure of 7 MPa, and the pressure on the secondary loop side is 11 MPa. During the start of the reactor, the pressure of the primary loop is about 4 MPa, and the secondary loop is filled with water to increase the pressure. Therefore, after the reactor is tripped, the pressure reduction operation is carried out. Here, the cooling interface is selected as the pressure reduction path, the pressure of the primary loop is slowly reduced, the helium is discharged into the helium storage tank 3 as the second helium storage, a small flow of the helium pressure reduction cycle is realized, and the purpose of reducing the temperature of the upper chamber of the core is achieved. The pressure reduction range cannot be lower than 4 MPa, the pressure difference between the primary loop and the secondary loop is ensured to be within the limit, and the safety of the steam generator is beneficial. When the temperature of the top chamber of the core is still relatively high and the increasing trend does not change during the pressure reduction process of the reactor, the helium storage tank 3 as the first helium storage supplies gas through the small flow cooling interface, realizes the pressure increase cycle for cooling, and observes the temperature rise change. The maximum pressure of the pressure increase and temperature reduction cannot exceed the operating pressure 7 MPa. When the temperature near the top chamber of the core approaches the metal temperature limit 500℃, the gas is taken from the small flow cooling interface, pressurized by the helium compressor 6, and sent to the top cavity of the core through the absorber ball subsystem 4. The flow is controlled by the regulating valve on the absorber ball subsystem 4. The absorber ball has multiple groups, and according to the temperature change trend, 1-6 groups can be selected for ventilation cooling. The fast protection absorber ball level meter 11 ensures its operating environment. When the temperature of the top cavity of the core still continues to rise rapidly using the above method, the gas is taken from the small flow cooling interface, pressurized by the helium compressor 6, and blown into the upper part of the core from the fuel loading and unloading subsystem 5. The helium flow is adjusted by the gas supply valve, so as to achieve the purpose of reducing the temperature of the top of the core. The helium flow using this cooling method is usually large, and the temperature rise is quickly suppressed. In order to avoid the change of the reactivity of the reactor caused by the rapid reduction of the temperature of the upper chamber of the core, the source range meter count rate is closely monitored during the small flow cooling. At the same time, the helium cooling flow is adjusted to suppress the temperature rise as the control target, realize the slow change of the temperature, and avoid the rapid decrease of the temperature.

[0060] Although the embodiments of the present application are described in conjunction with the drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and changes fall within the scope defined by the appended claims.

Claims

1. A high-temperature gas-cooled reactor cooling system, characterized in that, include: The reactor body (1) is connected to the steam generator (2). The steam generator (2) is connected to a helium supply and exhaust pipeline (7). Both ends of the helium supply and exhaust pipeline (7) are connected to the cooling interface of the steam generator (2). The helium supply and exhaust pipeline (7) is connected in parallel to a first helium storage unit and a second helium storage unit. The helium pressure in the first helium storage unit is greater than the primary loop helium pressure, and the helium pressure in the second helium storage unit is less than the primary loop helium pressure. The first cooling pipeline (8) has one end connected to the helium supply and exhaust pipeline (7) between the first helium storage unit and the steam generator (2), and the other end connected to the absorber subsystem (4), which is connected to the top of the reactor body (1).

2. The high-temperature gas-cooled reactor cooling system according to claim 1, characterized in that, It also includes a second cooling pipeline (9), one end of which is connected to the first cooling pipeline (8) and the other end is connected to the fuel loading and unloading subsystem (5), which is connected to the top of the reactor body (1).

3. The high-temperature gas-cooled reactor cooling system according to claim 2, characterized in that, A helium compressor (6) is installed on the first cooling pipeline (8), and the second cooling pipeline (9) is connected downstream of the helium compressor (6).

4. The high-temperature gas-cooled reactor cooling system according to any one of claims 1 to 3, characterized in that, The absorber ball subsystem (4) is equipped with a regulating valve, which is used to control the flow rate of helium gas flowing through the absorber ball subsystem (4) to the reactor body (1).

5. The high-temperature gas-cooled reactor cooling system according to any one of claims 1 to 3, characterized in that, The absorption ball subsystem (4) is installed in multiple sets.

6. The high-temperature gas-cooled reactor cooling system according to any one of claims 1 to 3, characterized in that, A temperature monitoring device (10) is installed inside the reactor body (1), and the temperature monitoring device (10) is arranged near the top of the reactor body (1).

7. A cooling method for a high-temperature gas-cooled reactor after an emergency shutdown, characterized in that, The application of the high-temperature gas-cooled reactor cooling system according to any one of claims 1 to 6 includes the following steps: The reactor body (1) is shut down in an emergency. The main helium blower stops running and helium is discharged to the second helium storage unit through the cooling interface of the steam generator (2) to reduce the helium pressure in the primary loop. During the process of reducing the pressure of the primary circuit, if the temperature of the top chamber of the reactor body (1) is not lower than the preset temperature value and the temperature increase trend is not less than the preset temperature increase value, the first helium storage unit supplies helium to the primary circuit through another cooling interface of the steam generator (2) to increase the helium pressure of the primary circuit. If the temperature of the top chamber of the reactor body (1) exceeds the temperature threshold, part of the helium gas discharged from the first helium storage device is introduced into the top chamber of the reactor body (1) through the first cooling pipeline (8) and the absorption ball subsystem (4).

8. The cooling method after an emergency shutdown of a high-temperature gas-cooled reactor according to claim 7, characterized in that, Also includes: Part of the helium gas passing through the first cooling pipeline (8) enters the second cooling pipeline (9) and is then introduced into the top chamber of the reactor body (1) through the fuel loading and unloading subsystem (5).

9. The cooling method after an emergency shutdown of a high-temperature gas-cooled reactor according to claim 7, characterized in that, In the step of reducing the primary loop helium pressure, the primary loop helium pressure shall not be less than the primary loop required pressure during the startup of the reactor body (1).

10. The cooling method after an emergency shutdown of a high-temperature gas-cooled reactor according to claim 7, characterized in that, In the step of increasing the primary loop helium pressure, the primary loop helium pressure is not greater than the primary loop maintenance pressure during normal operation of the reactor body (1).

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