Primary loop system of high-temperature gas cooled reactor

Abstract

The invention belongs to the technical field of nuclear energy, and particularly relates to a high-temperature gas cooled reactor primary loop system which comprises a reactor pressure vessel, reactor internals, a high-temperature gas cooled reactor core, a fused salt heat exchanger and a hot gas conduit. Reactor internals are mounted in the reactor pressure vessel, and a high-temperature gas cooled reactor core is filled in an inner cavity of the reactor internals. And a low-temperature helium inlet is formed in the top of the reactor internals. And one end of the hot air conduit is connected with the high-temperature gas cooled reactor core, and the other end of the hot air conduit is connected with the molten salt heat exchanger to form a circulation loop. Helium-molten salt heat exchange is realized by adopting the molten salt heat exchanger, so that the problems that the helium side and the water side of a steam generator adopted at present are both under high-temperature and high-pressure working conditions, a complex auxiliary system needs to be arranged, the system is huge, the equipment cost is high, and a reactor core water inlet accident is easily caused by breakage of a heat exchange pipe on the water side of a secondary loop of the steam generator are solved.

Description

Technical Field

[0001] This application belongs to the field of nuclear energy technology, specifically relating to a primary loop system for a high-temperature gas-cooled reactor. Background Technology

[0002] High-temperature gas-cooled reactors (HTGRs) are a representative type of fourth-generation nuclear power technology, and their inherent safety, high efficiency, and versatility have made them a key technology for global energy transition. The primary loop system of an HTGR uses helium as a coolant, and a steam generator facilitates energy exchange between helium and water, thereby achieving efficient transfer and recycling of nuclear fission heat. Currently used steam generators operate under high temperature and high pressure conditions on both the helium and water sides, requiring complex auxiliary systems that are large and costly. Furthermore, the secondary loop water side of the steam generator is under high pressure; if a heat transfer tube ruptures, secondary loop water could enter the primary loop, leading to a core flooding accident. Summary of the Invention

[0003] In view of this, this application provides a high-temperature gas-cooled reactor primary loop system, which uses a molten salt heat exchanger to achieve helium-molten salt heat exchange, in order to solve the problems that currently used steam generators operate under high temperature and high pressure conditions on both the helium side and the water side, requiring complex auxiliary systems, resulting in large systems, high equipment costs, and the risk of core flooding accidents caused by the rupture of the secondary loop water-side heat exchange tubes of the steam generator.

[0004] This application provides a primary loop system for a high-temperature gas-cooled reactor (HTGR), comprising a reactor pressure vessel, in-core components, an HTGR core, a molten salt heat exchanger, and hot gas ducts. The in-core components are installed inside the reactor pressure vessel, and their internal chambers are filled with the HTGR core. A cryogenic helium inlet is located at the top of the in-core components. The hot gas ducts are of a sheathed structure, with one end connected to the HTGR core and the other end connected to the molten salt heat exchanger, forming a circulation loop. This loop supplies high-temperature helium flowing out of the HTGR core to the molten salt heat exchanger and also supplies cryogenic helium after heat exchange to the HTGR core. The molten salt heat exchanger is used to connect to the secondary loop system of the HTGR, supplying high-temperature molten salt after heat exchange to the secondary loop system.

[0005] In one specific embodiment of this application, the hot gas duct includes a cryogenic helium channel and a high-temperature helium channel. The reactor pressure vessel is connected to the molten salt heat exchanger through the cryogenic helium channel and the high-temperature helium channel.

[0006] In one specific embodiment of this application, the molten salt heat exchanger includes a shell-side enclosure and a lower header, heat exchange tubes, and an upper header located within the shell-side enclosure. The lower header is connected to the bottom end of the heat exchange tubes and is connected to a high-temperature helium gas channel. The upper header is connected to the top end of the heat exchange tubes and is connected to a low-temperature helium gas channel. The shell-side enclosure has a molten salt inlet and a molten salt outlet. The molten salt outlet is used to connect to the secondary loop system of the high-temperature gas-cooled reactor.

[0007] In one specific embodiment of this application, the secondary side of the shell-side enclosure is designed with a slight positive pressure. The slight positive pressure ranges from no more than 1 MPa and is higher than the external atmospheric pressure.

[0008] In one specific embodiment of this application, the molten salt heat exchanger further includes a baffle plate. The baffle plate is installed on the left side of the cryogenic helium gas channel to separate the heat exchange tubes from the cryogenic helium gas channel on the right side.

[0009] In one specific embodiment of this application, a lower junction box inspection port is provided on the outside of the lower junction box, and an upper junction box inspection port is provided on the outside of the upper junction box. Both the lower junction box inspection port and the upper junction box inspection port are used for in-service inspection of the primary loop system boundary.

[0010] In one specific embodiment of this application, the molten salt heat exchanger further includes two rows of safety relief devices and corresponding liquid level measuring devices. The two rows of safety relief devices and corresponding liquid level measuring devices are installed at the top of the shell-side enclosure. The normal operation sequence of the safety relief devices is used for the recovery of helium micro-leakage, and the accident operation sequence of the safety relief devices is used for helium recovery in the event of a primary loop rupture accident.

[0011] In one specific embodiment of this application, the molten salt heat exchanger further includes an insulation structure that covers the surface of the shell-side containment body.

[0012] In one specific embodiment of this application, the molten salt heat exchanger further includes an insulating sleeve. The insulating sleeve is installed at the connection between the high-temperature helium gas channel and the lower header.

[0013] In one specific embodiment of this application, the cryogenic helium channel is connected to an expansion joint, which is used to eliminate thermal stress damage to the cryogenic helium channel.

[0014] In one specific embodiment of this application, the molten salt heat exchanger is a vertical, shell-and-tube heat exchanger, arranged side by side with the reactor pressure vessel. The tube-side fluid is helium, and the shell-side fluid is molten salt, with countercurrent heat exchange between the tube-side and shell-side fluids.

[0015] The beneficial effects of this technical solution are as follows: High-temperature gas-cooled reactor (HTGR) core outputs high-temperature helium to the molten salt heat exchanger via hot gas ducts. After heat exchange in the molten salt heat exchanger, the high-temperature helium forms low-temperature helium. This low-temperature helium then re-enters the HTGR core through the hot gas ducts and is reheated. The high-temperature molten salt in the molten salt heat exchanger then enters the HTGR secondary loop system. By repeating the above process, heat exchange between the HTGR and molten salt can be effectively achieved, thereby expanding the market for comprehensive utilization of HTGR nuclear energy. Furthermore, this technical solution uses a molten salt heat exchanger to achieve helium-molten salt heat exchange. On one hand, the molten salt medium in the molten salt heat exchanger has a high heat storage density and heat transfer coefficient, and the molten salt heat exchanger is small in size, which is beneficial for the miniaturization of the HTGR primary loop system. Moreover, compared to the helium-water loop, the equipment cost is lower. On the other hand, the molten salt side of the secondary loop is under low pressure. In the event of an accident, the primary loop helium is released into the secondary loop containment body, where it is collected, purified, and reused through the release channels, effectively preventing core flooding accidents. In addition, the molten salt heat exchanger design takes into account the heat transfer and heat storage properties of molten salt, which can buffer the fluctuations in the heating network and is more suitable for nuclear energy heat utilization scenarios. Attached Figure Description

[0016] Figure 1 The diagram shown is a structural schematic of a high-temperature gas-cooled reactor primary loop system provided in an embodiment of this application.

[0017] Figure 2 As shown Figure 1 The diagram shows a partially enlarged view of the area near the lower header in a primary loop system of a high-temperature gas-cooled reactor.

[0018] Figure 3 As shown Figure 1 This is another enlarged schematic diagram of a location near the lower header in a primary loop system of a high-temperature gas-cooled reactor.

[0019] Figure 4 As shown Figure 1 The diagram shows a partially enlarged view of the area near the upper header in a primary loop system of a high-temperature gas-cooled reactor.

[0020] In the diagram, 1. Reactor pressure vessel; 2. Carbon reactor internals; 3. Graphite reactor internals; 4. High-temperature gas-cooled reactor core; 5. Cryogenic helium inlet; 6. Cryogenic helium passage; 7. High-temperature helium passage; 8. Molten salt heat exchanger; 9. Lower header; 10. Heat exchange tube; 11. Upper header; 12. Expansion joint; 13. Molten salt inlet; 14. Molten salt outlet; 15. Divider; 16. Safety relief device; 17. Insulating sleeve; 18. Graphite inner sleeve; 19. Metal outer sleeve; 20. Lower header inspection port; 21. Upper header inspection port. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] At least one embodiment of this application provides a primary loop system for a high-temperature gas-cooled reactor, see reference. Figure 1 The primary loop system of the high-temperature gas-cooled reactor (HTGR) includes a reactor pressure vessel 1, in-core components, a HTGR core 4, a molten salt heat exchanger 8, and hot gas ducts. The reactor pressure vessel 1 houses the in-core components, and the internal chambers of the in-core components are filled with the HTGR core 4. A cryogenic helium inlet 5 is located at the top of the in-core components. The hot gas ducts are of a sleeve-type structure, with one end connected to the HTGR core 4 and the other end connected to the molten salt heat exchanger 8, forming a circulation loop. This loop supplies high-temperature helium flowing out of the HTGR core 4 to the molten salt heat exchanger 8 and also supplies cryogenic helium after heat exchange to the HTGR core 4. The molten salt heat exchanger 8 is used to connect to the secondary loop system of the HTGR, supplying high-temperature molten salt after heat exchange to the secondary loop system.

[0023] It should be noted that reactor pressure vessel 1 is the component that supports and encloses the entire reactor core, internal components, and bears enormous loads. The high-temperature gas-cooled reactor core 4 can be composed of spherical fuel elements. The heat generated by the nuclear fission reaction in the high-temperature gas-cooled reactor core 4 heats the cryogenic helium flowing within it into high-temperature helium.

[0024] For example, the reactor internals include carbon reactor internals 2 and graphite reactor internals 3. The internal cavity of graphite reactor internals 3 is filled with a high-temperature gas-cooled reactor core 4. Carbon reactor internals 2 are used to support graphite reactor internals 3 and the pebble bed core. Graphite reactor internals 3 form the core cavity, constitute the fuel sphere flow channel, and constitute the flow channel for the helium heat transfer gas.

[0025] According to the technical solution provided in the embodiments of this application, the high-temperature gas-cooled reactor core 4 outputs high-temperature helium gas to the molten salt heat exchanger 8 through a hot gas duct. After heat exchange in the molten salt heat exchanger 8, the high-temperature helium gas forms low-temperature helium gas after heat exchange. The low-temperature helium gas enters the high-temperature gas-cooled reactor core 4 through the hot gas duct and is heated again. The high-temperature molten salt after heat exchange in the molten salt heat exchanger 8 enters the high-temperature gas-cooled reactor secondary loop system. By repeating the above process, heat exchange between the high-temperature gas-cooled reactor and the molten salt can be effectively realized, thereby expanding the market for comprehensive utilization of nuclear energy from high-temperature gas-cooled reactors. Furthermore, this embodiment employs a molten salt heat exchanger 8 to achieve helium-molten salt heat exchange. On one hand, the molten salt medium in the molten salt heat exchanger 8 has a high heat storage density and heat transfer coefficient, and the molten salt heat exchanger 8 is small in size, which is beneficial for the miniaturization of the primary loop system of the high-temperature gas-cooled reactor. Moreover, compared to the helium-water loop, the equipment cost is lower. On the other hand, the molten salt side of the secondary loop is under low pressure. Under accident conditions, the helium from the primary loop is released into the secondary loop containment body, where it is collected, purified, and reused through the release channels on the containment body, effectively preventing core flooding accidents. In addition, the molten salt heat exchanger 8 is designed to take into account the heat transfer and heat storage properties of molten salt, providing a buffer against heat network fluctuations, making it more suitable for nuclear energy heat utilization scenarios.

[0026] In at least one embodiment of this application, the hot gas duct includes a cryogenic helium channel 6 and a high-temperature helium channel 7. The reactor pressure vessel 1 is connected to the molten salt heat exchanger 8 through the cryogenic helium channel 6 and the high-temperature helium channel 7. Thus, cryogenic helium enters the helium flow channel within the reactor pressure vessel 1 through the cryogenic helium channel 6, flows upward through the cryogenic helium inlet 5 at the top of the reactor internals, and enters the high-temperature gas-cooled reactor core 4. The cryogenic helium is then heated again by the nuclear fission reaction in the high-temperature gas-cooled reactor core 4, thereby repeating the above-mentioned operation process to achieve heat exchange between helium and molten salt within the molten salt heat exchanger 8.

[0027] It should be noted that the low-temperature helium channel 6 and the high-temperature helium channel 7 together constitute a hot gas duct.

[0028] For example, refer to Figure 2 The cryogenic helium channel 6 can be enclosed by a metal outer sleeve 19. The high-temperature helium channel 7 can be enclosed by a graphite inner sleeve 18. In this way, the cryogenic helium channel 6 and the high-temperature helium channel 7 form an isolation between the cold and hot helium gases.

[0029] In at least one embodiment of this application, the molten salt heat exchanger 8 includes a shell-side enclosure and a lower header 9, heat exchange tubes 10, and an upper header 11 located within the shell-side enclosure. The lower header 9 is connected to the bottom end of the heat exchange tubes 10 and is connected to the high-temperature helium channel 7. The upper header 11 is connected to the top end of the heat exchange tubes 10 and is connected to the low-temperature helium channel 6. The shell-side enclosure is provided with a molten salt inlet 13 and a molten salt outlet 14. The molten salt outlet 14 is used to connect to the secondary loop system of the high-temperature gas-cooled reactor. Thus, the high-temperature helium gas heated by the nuclear fission reaction in the core 4 of the high-temperature gas-cooled reactor enters the high-temperature helium channel 7 and then enters the lower header 9 of the molten salt heat exchanger 8. The helium gas that has undergone heat exchange in the heat exchange tubes 10 flows upward and converges into the upper header 11, while the low-temperature helium gas that has undergone heat exchange flows downward through the upper header 11 into the low-temperature helium channel 6. Low-temperature molten salt enters the shell side of molten salt heat exchanger 8 through molten salt inlet 13 and flows downward to exchange heat with high-temperature helium gas in heat exchange tube 10. After being heated to the target temperature, the high-temperature molten salt flows out of the shell side of molten salt heat exchanger 8 through molten salt outlet 14, realizing the heat conversion between helium gas and molten salt. The heat-loaded molten salt enters the secondary loop system.

[0030] It should be noted that the lower header 9 and the heat exchange tube 10 can be connected by internal welding. The heat exchange tube 10 can be an integral heat exchange tube, arranged in an equidistant square pattern.

[0031] In some embodiments, both the lower header 9 and the upper header 11 have uniformly distributed perforations on their walls. These perforations are connected to the heat exchange tubes 10. Thus, high-temperature helium gas flows upward through the uniformly distributed perforations on the wall of the lower header 9 and enters the heat exchange tubes 10. The high-temperature helium gas enters the heat exchange tubes 10 and exchanges heat with the low-temperature molten salt in the shell side of the molten salt heat exchanger 8. The high-temperature helium gas is cooled to low-temperature helium gas in the tube side, and the low-temperature molten salt is heated to high-temperature molten salt in the shell side. The helium gas that has undergone heat exchange in the heat exchange tubes 10 then enters the upper header 11.

[0032] In at least one embodiment of this application, the secondary side of the shell-side containment is designed with a slight positive pressure. The slight positive pressure ranges from no more than 1 MPa and is higher than the external atmospheric pressure. This ensures that the pressure generated after helium diffuses into the gas cavity above the molten salt heat exchanger 8 under accident conditions is lower than the design pressure, and the containment has good containment under any operating condition. Furthermore, the molten salt heat exchanger 8 in this embodiment is smaller and more compact, and the slight positive pressure on the secondary side results in lower equipment costs compared to a helium-water loop.

[0033] In at least one embodiment of this application, the molten salt heat exchanger 8 further includes a partition 15. The partition 15 is installed on the left side of the cryogenic helium channel 6 to separate the heat exchange tube 10 from the cryogenic helium channel 6 on the right side.

[0034] In at least one embodiment of this application, reference is made to Figure 3 and Figure 4The lower junction box 9 is provided with a lower junction box inspection port 20 on its outside, and the upper junction box 11 is provided with an upper junction box inspection port 21 on its outside. Both the lower junction box inspection port 20 and the upper junction box inspection port 21 are used for in-service inspection of the primary loop system boundary.

[0035] In at least one embodiment of this application, the molten salt heat exchanger 8 further includes two rows of safety relief devices 16 and corresponding liquid level measuring devices. The two rows of safety relief devices 16 and corresponding liquid level measuring devices are installed at the top of the shell-side containment. The normal operation sequence of the safety relief devices 16 is used for the recovery of helium micro-leakage, and the accident operation sequence of the safety relief devices 16 is used for helium recovery under primary loop rupture accidents. Thus, the secondary loop molten salt side is under low pressure. Under accident conditions, primary loop helium leaks into the secondary loop containment, is collected, purified, and reused through the relief channels of the safety relief devices 16, effectively preventing water ingress accidents into the high-temperature gas-cooled reactor core 4.

[0036] In at least one embodiment of this application, the molten salt heat exchanger 8 further includes an insulation structure that covers the surface of the shell-side enclosure. Thus, the insulation structure can reduce heat transfer losses.

[0037] In at least one embodiment of this application, the molten salt heat exchanger 8 further includes an insulating sleeve 17. The insulating sleeve 17 is installed at the connection between the high-temperature helium gas channel 7 and the lower header 9. In this way, the insulating sleeve 17 can effectively reduce heat loss.

[0038] In at least one embodiment of this application, the cryogenic helium channel 6 is connected to an expansion joint 12, which is used to eliminate thermal stress damage to the cryogenic helium channel 6.

[0039] In at least one embodiment of this application, the molten salt heat exchanger 8 is a vertical, shell-and-tube heat exchanger, arranged side by side with the reactor pressure vessel 1, with helium as the tube-side fluid and molten salt as the shell-side fluid, and the tube-side and shell-side fluids exchange heat in countercurrent.

[0040] In the above embodiment, the high-temperature gas-cooled reactor core 4 outputs high-temperature helium gas to the high-temperature helium gas channel 7 of the hot gas duct. The high-temperature helium gas in the high-temperature helium gas channel 7 enters the heat exchange tube 10 through the lower header 9 of the molten salt heat exchanger 8. The high-temperature helium gas flows upward in the heat exchange tube 10 and exchanges heat countercurrently with the low-temperature molten salt in the shell side of the molten salt heat exchanger 8. After heat exchange, the low-temperature helium gas enters the upper header 11 and then enters the high-temperature gas-cooled reactor core 4 through the low-temperature helium gas channel 6 of the hot gas duct to be heated again. The high-temperature molten salt after heat exchange enters the high-temperature gas-cooled reactor secondary loop system. By repeating the above process flow, heat exchange between the high-temperature gas-cooled reactor and the molten salt can be effectively realized, thereby expanding the market for the comprehensive utilization of nuclear energy from high-temperature gas-cooled reactors.

[0041] It should be noted that the combination of the technical features in the embodiments of this application is not limited to the combination methods described in the embodiments of this application or the combination methods described in specific embodiments. All technical features described in this application can be freely combined or combined in any way, unless they contradict each other.

[0042] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the term "comprising" only indicates that it includes the explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0043] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications or equivalent substitutions made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A primary loop system for a high-temperature gas-cooled reactor, characterized in that, This includes the reactor pressure vessel, in-core components, high-temperature gas-cooled reactor core, molten salt heat exchanger, and hot gas ducts. The reactor pressure vessel houses the in-core components, whose internal chambers are filled with the high-temperature gas-cooled reactor core. A cryogenic helium inlet is located at the top of the in-core components. The hot gas duct is a sleeve-type structure, with one end connected to the high-temperature gas-cooled reactor core and the other end connected to the molten salt heat exchanger, forming a circulation loop. This loop supplies high-temperature helium flowing from the high-temperature gas-cooled reactor core to the molten salt heat exchanger and also supplies cryogenic helium after heat exchange to the high-temperature gas-cooled reactor core. The molten salt heat exchanger is connected to the high-temperature gas-cooled reactor secondary loop system, supplying high-temperature molten salt after heat exchange to the secondary loop system.

2. The high-temperature gas-cooled reactor primary loop system according to claim 1, characterized in that, The hot gas duct includes a cryogenic helium channel and a high-temperature helium channel, and the reactor pressure vessel is connected to the molten salt heat exchanger through the cryogenic helium channel and the high-temperature helium channel.

3. The high-temperature gas-cooled reactor primary loop system according to claim 2, characterized in that, The molten salt heat exchanger includes a shell-side enclosure and a lower header, heat exchange tubes, and an upper header located within the shell-side enclosure. The lower header is connected to the bottom end of the heat exchange tubes and is connected to the high-temperature helium gas channel. The upper header is connected to the top end of the heat exchange tubes and is connected to the low-temperature helium gas channel. The shell-side enclosure is provided with a molten salt inlet and a molten salt outlet, and the molten salt outlet is used to connect to the secondary loop system of the high-temperature gas-cooled reactor.

4. The high-temperature gas-cooled reactor primary loop system according to claim 3, characterized in that, The molten salt heat exchanger also includes a partition plate, which is installed on the left side of the cryogenic helium gas channel and is used to separate the heat exchange tube from the cryogenic helium gas channel on the right side.

5. A high-temperature gas-cooled reactor primary loop system according to claim 3, characterized in that, The secondary side of the shell-side enclosure is designed to be slightly positive, with the range of slightly positive pressure not exceeding 1 MPa, which is higher than the external atmospheric pressure.

6. The high-temperature gas-cooled reactor primary loop system according to claim 3, characterized in that, The lower junction box is provided with a lower junction box inspection port on its outside, and the upper junction box is provided with an upper junction box inspection port on its outside. Both the lower junction box inspection port and the upper junction box inspection port are used for in-service inspection of the primary loop system boundary.

7. The high-temperature gas-cooled reactor primary loop system according to claim 3, characterized in that, Both the upper and lower headers have evenly distributed pipe holes on their walls. The heat exchange tube is an integrated heat exchange tube and is connected to the upper and lower headers by internal hole welding.

8. The high-temperature gas-cooled reactor primary loop system according to claim 3, characterized in that, The molten salt heat exchanger also includes two rows of safety relief devices and corresponding liquid level measuring devices. The two rows of safety relief devices and corresponding liquid level measuring devices are installed on the top of the shell-side enclosure. The normal operation sequence of the safety relief devices is used for the recovery of helium micro-leakage, and the accident operation sequence of the safety relief devices is used for the recovery of helium under the condition of primary loop tube rupture.

9. A high-temperature gas-cooled reactor primary loop system according to claim 3, characterized in that, The molten salt heat exchanger also includes an insulation structure that covers the surface of the shell-side containment body.

10. A high-temperature gas-cooled reactor primary loop system according to claim 3, characterized in that, The molten salt heat exchanger also includes an insulating sleeve, which is installed at the connection between the high-temperature helium gas channel and the lower header.

11. A high-temperature gas-cooled reactor primary loop system according to any one of claims 2 to 10, characterized in that, The cryogenic helium channel is connected to an expansion joint, which is used to eliminate thermal stress damage to the cryogenic helium channel.

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