Fuel salt and proliferation salt isolated thorium-based molten salt reactor system and operation method thereof

Abstract

The invention provides a thorium-based molten salt reactor system with fuel salt and proliferation salt isolated and an operation method of the thorium-based molten salt reactor system. The system comprises: a loop system comprising a reactor body, a fuel salt loop, a fuel salt circulating in the fuel salt loop, a proliferative salt loop, and a proliferative salt circulating in the proliferative salt loop, where the fuel salt comprises uranium-233 and does not comprise thorium-232, the proliferative salt comprises thorium-232 and does not comprise fissionable nuclear fuel, and the proliferative salt comprises uranium-233 and does not comprise thorium-232 and does not comprise fissionable nuclear fuel; the fuel salt loop and the proliferation salt loop are physically isolated in the reactor body and realize neutronics coupling; the reactor body comprises a main container and a plurality of fuel assemblies arranged in the main container, each fuel assembly comprises a fuel pipe made of an isolation material, and the two ends of each fuel pipe are in sealed connection with a lower cavity and an upper cavity in the main container respectively; the fuel pipe is wrapped with moderator blocks, and circulation channels are formed between the moderator blocks. Fuel salt of the fuel salt loop flows through the interior of the fuel pipe, and proliferative salt of the proliferative salt loop flows through a circulation channel between the moderator blocks.

Description

Technical Field

[0001] This application relates primarily to the field of nuclear reactor technology, and in particular to a thorium-based molten salt reactor system with fuel salt and breeder salt isolated, and its operation method. Background Technology

[0002] A liquid-fuel molten salt reactor is an advanced reactor that uses nuclear fuel directly dissolved in molten fluoride salt as both fuel and coolant. Traditional designs for liquid-fuel molten salt reactors typically mix fuel (such as uranium-233) and breeder material (thorium-232) in the same molten salt and circulate it within a core containing a graphite moderator. While this design enables the conversion of thorium to uranium-233, it also presents two major challenges: On the one hand, the reprocessing is extremely complex: the molten salt after operation contains fission products, minor actinides, unreacted thorium-232, the intermediate product protactinium-233, and uranium-233. Separating and extracting useful uranium-233 and treating the waste requires processing multiple chemically different substances in the same process, which is complex and costly.

[0003] On the other hand, obtaining initial feedstock is difficult: uranium-233 does not exist in nature, and the source of initial feedstock must be solved to start the thorium-uranium cycle. Traditional mixed-fuel molten salt reactor designs are difficult to produce uranium-233 suitable for their own initial loading in an efficient and clean manner.

[0004] Therefore, there is an urgent need for a new configuration of thorium-based molten salt reactor that can simplify the post-processing procedure and effectively solve the initial charging problem. Summary of the Invention

[0005] The technical problem to be solved by this application is to provide a thorium-based molten salt reactor system and its operation method that isolates fuel salt and breeder salt, aiming to simplify reprocessing and establish a feasible self-sustaining cycle of thorium-uranium fuel by physically isolating fuel function and breeder function.

[0006] To address the aforementioned technical problems, this application provides a thorium-based molten salt reactor system with isolated fuel salt and breeder salt, comprising: a primary loop system including a reactor body, a fuel salt loop, fuel salt circulating in the fuel salt loop, a breeder salt loop, and breeder salt circulating in the breeder salt loop, wherein the fuel salt contains uranium-233 but does not contain thorium-232, and the breeder salt contains thorium-232 but does not contain fissile nuclear fuel; the fuel salt loop and the breeder salt loop are physically isolated within the reactor body and neutronically coupled; the reactor body includes a main container and multiple fuel assemblies disposed therein, each fuel assembly including a fuel tube made of insulating material, the two ends of the fuel tube being sealed to a lower chamber and an upper chamber within the main container, respectively; the fuel tube is externally wrapped with moderator blocks, and flow channels are formed between the moderator blocks; the fuel salt of the fuel salt loop flows through the interior of the fuel tube, and the breeder salt of the breeder salt loop flows through the flow channels between the moderator blocks.

[0007] Optionally, the thickness of the moderator block 13 is reduced in the axial end regions of the fuel pipe to form an axial conversion zone.

[0008] Optionally, the fuel pipe is made of silicon carbide or metal.

[0009] Optionally, the operating pressure of the breeding salt circuit is configured to be higher than that of the fuel salt circuit.

[0010] Optionally, the system further includes: a fuel salt processing system connected to the fuel salt circuit for removing fission products and secondary actinides from the fuel salt; and a breeder salt processing system connected to the breeder salt circuit for extracting protactinium-233 and uranium-233 generated from the breeder salt.

[0011] Optionally, the fuel salt processing system includes a degassing unit, a fluorination volatilization unit, a vacuum distillation unit, and a fuel salt reconstitution unit; wherein, the inlet of the degassing unit is connected to the fuel salt circuit, the outlet of the degassing unit is connected to the inlet of the fluorination volatilization unit, the fluorination volatilization unit is provided with a uranium outlet and a deuranium salt outlet, the uranium outlet is used to output the extracted uranium and connect to the fuel salt reconstitution unit, the deuranium salt outlet is connected to the inlet of the vacuum distillation unit, the outlet of the vacuum distillation unit is connected to the fuel salt reconstitution unit, and the outlet of the fuel salt reconstitution unit is connected to the fuel salt circuit.

[0012] Optionally, the breeder salt treatment system includes a reduction extraction device, a back-extraction device, and a storage tank; wherein, the inlet of the reduction extraction device is connected to the breeder salt circuit for extracting protactinium-233 and uranium-233, and is provided with a purified salt outlet and an extractant phase outlet; the purified salt outlet is used to return the extracted purified breeder salt to the breeder salt circuit, and the extractant phase outlet is connected to the inlet of the back-extraction device, which is used to convert the extracted protactinium-233 and uranium-233 into a molten salt containing protactinium-233 and uranium-233, and output it to the storage tank for storage.

[0013] Optionally, the system further includes a molten salt cooling circuit, comprising a cooling circuit main pump, a fuel salt heat exchanger, a breeder salt heat exchanger, a steam generator, and cooling molten salt circulating in the molten salt cooling circuit, wherein the cooling molten salt is configured to absorb the heat transferred by the fuel salt circuit and the breeder salt circuit, and output the heat to an energy conversion circuit; the energy conversion circuit is used to convert the heat into electrical energy.

[0014] Optionally, the molten salt cooling circuit is configured in series: the outlet of the main pump of the cooling circuit is connected to the inlet of the fuel salt heat exchanger, the outlet of the fuel salt heat exchanger is divided into a main stream and a regulating branch, the main stream is connected to the inlet of the steam generator, the regulating branch is connected to the inlet of the breeding salt heat exchanger via a first breeding salt heat exchange pump, and the outlet of the breeding salt heat exchanger merges with the pipeline leading to the steam generator.

[0015] Optionally, the molten salt cooling circuit is configured in parallel: the outlet of the main pump of the cooling circuit is connected to a flow path distribution node; from this node, the molten salt is divided into independent fuel salt cooling branches and breeder salt cooling branches; the fuel salt cooling branch is connected to the inlet of the fuel salt heat exchanger via a fuel salt heat exchange pump, and the breeder salt cooling branch is connected to the inlet of the breeder salt heat exchanger via a second breeder salt heat exchange pump; the outlet of the fuel salt heat exchanger and the outlet of the breeder salt heat exchanger merge and are then connected to the inlet of the steam generator.

[0016] Optionally, the fuel salt heat exchanger and the breeder salt heat exchanger are integrated into a single integrated heat exchanger; wherein, the fuel salt of the fuel salt circuit flows through a first independent channel within the integrated heat exchanger, the breeder salt of the breeder salt circuit flows through a second independent channel within the integrated heat exchanger, and the cooling molten salt of the molten salt cooling circuit flows through a common heat transfer zone of the integrated heat exchanger, so as to simultaneously remove heat from the fuel salt and the breeder salt.

[0017] To address the aforementioned technical problems, this application provides an operation method for a thorium-based molten salt reactor system, comprising the following modes: Production mode: The reactor is operated by loading low-enriched uranium as start-up fuel into the fuel salt loop, while the breeder salt loop is used to produce and accumulate uranium-233; Self-sustaining mode: When the accumulated uranium-233 reaches a predetermined threshold, the start-up fuel is replaced with uranium-233, and the reactor is operated in a state where it relies solely on the uranium-233 generated by its own conversion to maintain criticality.

[0018] This application discloses a thorium-based molten salt reactor system and its operation method that isolates fuel salt and breeder salt. By arranging uranium-233-containing fuel salt and thorium-232-containing breeder salt in separate loops, physical isolation between the two is achieved. This design effectively avoids the problem of high mixing of multiple nuclides in traditional liquid fuel molten salt reactors, ensuring that the fuel salt does not contain thorium and eliminating the need for protactinium-233 extraction, thus significantly simplifying the fission product removal process. At the same time, the breeder salt contains almost no fission products, requiring only the extraction of protactinium-233 and uranium-233, significantly reducing the complexity and technical difficulty of chemical reprocessing and improving the safety and sustainability of system operation. Furthermore, through the breeder salt loop and breeder salt processing system, uranium-233 initial charge can be prepared efficiently and cleanly, successfully overcoming the startup bottleneck of the thorium-uranium cycle. Attached Figure Description

[0019] The accompanying drawings are included to provide a further understanding of this application. They are incorporated into and constitute a part of this application. The drawings illustrate embodiments of this application and, together with this specification, serve to explain the principles of this application.

[0020] Figure 1 This is a schematic diagram of a thorium-based molten salt reactor system with fuel salt and breeder salt isolated according to an embodiment of this application.

[0021] Figure 2 This is a schematic diagram of a fuel salt processing system according to an embodiment of this application.

[0022] Figure 3 This is a schematic diagram of a salt production system according to an embodiment of this application.

[0023] Figure 4 This is a schematic diagram of a two-loop system with a parallel structure according to an embodiment of this application.

[0024] Figure 5 This is a schematic diagram of a two-loop system with an integrated structure according to an embodiment of this application.

[0025] Figure 6 This is a schematic diagram of the operation method of a thorium-based molten salt reactor system according to an embodiment of this application.

[0026] Figure 7This is a schematic diagram of the operation method of a thorium-based molten salt reactor system according to another embodiment of this application.

[0027] Figure label: 1. Fuel salt circuit; 2. Proliferating salt circuit; 3. Molten salt cooling circuit; 4. Energy conversion circuit; 5. The main body; 6. Fuel molten salt pump; 7. Fuel salt heat exchanger; 8. Breeding molten salt pump; 9. Breeding salt heat exchanger; 10. Fuel pipe; 11. Inferior chamber; 12. Upper chamber; 13. Moderator blocks; 14. Axial conversion zone; 15. First entrance; 16. First Exit; 17. Salt processing system; 18. Second entrance; 19 Second Exit; 20. Salt enhancement system; 21. Main pump for cooling circuit; 22 First-stage salt-breeding heat exchange pump; 23. Steam generator; 24. Degassing device; 25. Fluoride volatilization unit; 26. Fuel salt remodeling unit; 27. Vacuum distillation apparatus; 28. Reduction extraction apparatus; 29. Back-extraction device; 30 storage tanks; 31. Integrated heat exchanger; 32 Second-stage salt-breeding heat exchange pump; 33. Fuel salt heat exchange pump. Detailed Implementation

[0028] 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 should fall within the scope of protection of this application.

[0029] Figure 1This is a schematic diagram of a thorium-based molten salt reactor system with fuel salt and breeder salt isolated according to an embodiment of this application. Figure 1 As shown, in this embodiment, the thorium-based molten salt reactor system 100, which isolates fuel salt and breeder salt, includes a primary loop system, a fuel salt processing system 17, and a breeder salt processing system 20. The primary loop system is the core of nuclear heat generation and transfer, including the reactor body 5, the fuel salt loop 1, the fuel salt circulating in the fuel salt loop 1, the breeder salt loop 2, and the breeder salt circulating in the breeder salt loop 2. The fuel salt loop 1 and the breeder salt loop 2 are physically isolated within the reactor body 5 and achieve neutron coupling.

[0030] Heap body 5 is key to achieving physical isolation. For example... Figure 1 As shown, the fuel assembly contains multiple fuel assemblies. The core of each fuel assembly is a fuel tube 10, made of a high-temperature resistant, corrosion-resistant, radiation-resistant, low-neutron-absorption, and high-strength insulating material. The fuel tube 10 is vertically arranged, with its two ends sealed to the lower chamber 11 and the upper chamber 12, respectively. A moderator block 13 is tightly wrapped around the fuel tube 10; the moderator block material is, for example, solid graphite moderator. The gaps between the moderator blocks 13 form breeding salt channels. The fuel salt in fuel salt circuit 1 uses uranium-233 as fuel and does not contain thorium-232. The fuel salt flows inside the fuel tube 10, undergoes a fission reaction, and releases neutrons and heat. The breeding salt in breeding salt circuit 2 contains thorium-232 and does not contain fissile nuclear fuel. The breeding salt flows in the gaps of the moderator blocks 13, where the thorium-232 absorbs neutrons leaking from the fuel tube 10, converting into protactinium-233, which then decays into uranium-233.

[0031] Fuel salt circuit 1 includes a molten salt pump 6, a fuel salt heat exchanger 7, and corresponding piping. Fuel salt processing system 17 is connected to fuel salt circuit 1 and is used to remove fission products and minor actinide nuclides from the fuel salt. Breeder salt circuit 2 includes a breeder salt pump 8, a breeder salt heat exchanger 9, and corresponding piping. Breeder salt processing system 20 is connected to breeder salt circuit 2 and is used to extract protactinium-233 and uranium-233 generated from the breeder salt.

[0032] In this system, the fuel salt loop 1 operates at atmospheric pressure. The fuel salt enters the lower chamber 11 through the first inlet 15, and then flows into the fuel pipe 10. Here, the fuel salt undergoes a chain fission reaction, generating a large amount of heat and releasing more neutrons. Some of these neutrons pass through the fuel pipe 10 and the moderator block 13 and react with the breeder salt, participating in the thorium conversion. The fuel salt flows out of the fuel pipe 10 and into the upper chamber 12 for mixing, and then flows out of the reactor body 5 through the first outlet 16. Here, some of the fuel salt is diverted into the fuel salt processing system 17 for online processing before flowing back. The mixed fuel salt enters the fuel molten salt pump 6 to obtain forced circulation driving force. Subsequently, the fuel salt enters the fuel salt heat exchanger 7, which transfers heat to the molten salt cooling loop 3. Then, the fuel salt returns to the first inlet 15 and re-enters the reactor body 5 for circulation.

[0033] The operating pressure of breeder salt circuit 2 is slightly higher than that of fuel salt circuit 1. The breeder salt enters the main container through the second inlet 18, where thorium-232 absorbs neutrons generated and migrated from the fuel salt fission, converting them into uranium-233 and releasing a small amount of heat. Subsequently, the breeder salt flows out of the main container through the second outlet 19. A portion of the breeder salt is diverted into the breeder salt processing system 20 for online processing before flowing back. The mixed breeder salt enters the breeder molten salt pump 8 to obtain forced circulation driving force. It then enters the breeder salt heat exchanger 9, which transfers heat to the molten salt cooling circuit 3. After that, the breeder salt returns to the second inlet 18 and re-enters the main container for circulation.

[0034] The breeder salt loop 2 operates at a slightly higher pressure than the fuel salt loop 1. Even in the event of a minor leak, only a small amount of breeder salt without fission products will flow into the more complex fuel salt, preventing reverse leakage and ensuring that the breeder salt used for uranium-233 production will not be contaminated. This isolation method effectively prevents cross-contamination, ensuring the safety of system operation and the purity of the fuel cycle.

[0035] Figure 2 This is a schematic diagram of a fuel salt processing system according to an embodiment of this application. Figure 2 As shown, the fuel salt processing system 17 includes a degassing unit 24, a fluorination volatilization unit 25, a vacuum distillation unit 27, and a fuel salt reconstruction unit 26. The inlet of the degassing unit 24 is connected to the fuel salt circuit 1, and the outlet of the degassing unit 24 is connected to the inlet of the fluorination volatilization unit 25. The fluorination volatilization unit 25 has a uranium outlet and a deuranium salt outlet. The uranium outlet is used to output the extracted uranium and is connected to the fuel salt reconstruction unit 26. The deuranium salt outlet is connected to the inlet of the vacuum distillation unit 27, the outlet of the vacuum distillation unit 27 is connected to the fuel salt reconstruction unit 26, and the outlet of the fuel salt reconstruction unit 26 is connected to the fuel salt circuit 1.

[0036] The workflow of the fuel salt processing system 17 includes: after the fuel salt flows out of the reactor body 5, a portion is diverted into the degassing unit 24 to remove fission gases (such as xenon, krypton, etc.), and then passes through the fluorination volatilization unit 25 to remove uranium (mainly U) from the fuel salt. ) is converted into volatile U The uranium is then separated and extracted. The molten fuel salt after uranium extraction flows into vacuum distillation unit 27 to remove rare earth elements and other fission products. Subsequently, the clean carrier molten salt also enters fuel salt reconstruction unit 26, along with the aforementioned extracted U... Reconstitute the new fuel salt flow back to the fuel salt loop 1.

[0037] Figure 3 This is a schematic diagram of a salt production system according to an embodiment of this application. Figure 3 As shown, the breeding salt processing system 20 includes a reduction extraction device 28, a back-extraction device 29, and a storage tank 30. The inlet of the reduction extraction device 28 is connected to the breeding salt circuit 2, and it is used to extract protactinium-233 and uranium-233. It has a purified salt outlet and an extractant phase outlet. The purified salt outlet is used to return the extracted purified breeding salt to the breeding salt circuit 2. The extractant phase outlet is connected to the inlet of the back-extraction device 29, which is used to convert the extracted protactinium-233 and uranium-233 into a molten salt containing protactinium-233 and uranium-233, and then output it to the storage tank 30 for storage.

[0038] The workflow of the breeder salt processing system includes: after flowing out of the main container, the breeder salt enters the reduction extraction unit 28, where protactinium-233 and uranium-233 are selectively reduced and extracted. The purified breeder salt (purified salt outlet) is directly returned to breeder salt loop 2. The extract phase rich in protactinium-233 and uranium-233 (extract phase outlet) enters the back-extraction unit 29, where a molten salt product containing protactinium-233 and uranium-233 with a clearly defined composition is produced through the back-extraction process. This product is then sent to storage tank 30 for decay storage (protactinium-233 decays into uranium-233) for subsequent use as fuel.

[0039] The thorium-based molten salt reactor system of this application fundamentally simplifies the nuclear fuel cycle through physical isolation and functional decoupling of fuel salt and breeder salt: fuel salt reprocessing only requires the removal of fission products, and breeder salt reprocessing only requires the extraction of protactinium-233 / uranium-233. The two processes are independent and do not interfere with each other, greatly reducing the difficulty and cost of chemical separation. Secondly, through the breeder salt loop and breeder salt processing system, uranium-233 initial charge can be prepared efficiently and cleanly, achieving fuel self-sufficiency and breedering.

[0040] Optionally, such as Figure 1As shown, within the reactor body 5, near both ends of the fuel tubes 10, the thickness of the moderator block 13 is intentionally reduced, forming an axial conversion region 14 with clearly defined structural features and functions. This design is a significant manifestation of spatial optimization of the reactor core's neutronics performance. In the axial conversion region 14, due to the reduced moderator, the neutron moderation capability is weakened, resulting in a "harder" neutron energy spectrum compared to the active region. Furthermore, the breeder salt fraction in the axial conversion region 14 is increased to more effectively utilize the neutrons in this region for conversion. In other words, neutrons leaking axially from the active region might be absorbed by the structural materials or leak unnecessarily in a conventional homogeneous design. In this design, the axial conversion region 14 creates a "neutron trap," effectively utilizing these potentially lost neutrons for the breeder reaction, improving the neutron economy of the entire system and increasing the number of uranium-233 nucleons produced per unit of fission.

[0041] Optionally, the fuel tube 10 is made of silicon carbide. Silicon carbide fuel tubes have advantages such as light weight and low neutron absorption. In another embodiment, the fuel tube 10 is made of a metal material that is resistant to high temperature, corrosion, radiation, and has high structural strength. Due to the use of a metal material, the connection and sealing between the fuel tube and the upper and lower chambers is simpler and can be achieved using more conventional welding methods.

[0042] Optionally, the thorium-based molten salt reactor system 100, which isolates fuel salt from breeder salt, also includes a secondary loop system and a tertiary loop system. The secondary loop system serves as an intermediate cooling and safety barrier; the working fluid in the secondary loop system absorbs heat from the primary loop system and then transfers that heat to the tertiary loop system. For example... Figure 1 As shown, the secondary loop system is the molten salt cooling loop 3. The molten salt cooling loop 3 includes a cooling loop main pump 21, a fuel salt heat exchanger 7, a breeding salt heat exchanger 9, a steam generator 23, and cooling molten salt in the loop. The cooling molten salt in the molten salt cooling loop 3 absorbs heat from the fuel salt heat exchanger 7 and the breeding salt heat exchanger 9 sequentially or in parallel, and then transfers the heat to the tertiary loop system.

[0043] like Figure 1As shown, in this embodiment, the molten salt cooling circuit 3 is configured in a series structure. The outlet of the main pump 21 of the cooling circuit is connected to the inlet of the fuel salt heat exchanger 7. The outlet of the fuel salt heat exchanger 7 is divided into a main flow path and a regulating branch. The main flow path is connected to the inlet of the steam generator 23. The regulating branch is connected to the inlet of the breeder salt heat exchanger 9 via the first breeder salt heat exchanger pump 22. The outlet of the breeder salt heat exchanger 9 merges with the pipeline leading to the steam generator 23. The molten salt cooling circuit 3 is driven by the main pump 21 of the cooling circuit and operates at atmospheric pressure. The molten salt in the cooling circuit first enters the fuel salt heat exchanger 7 to remove the heat transferred from the fuel salt. Then, it is diverted through the first breeder salt heat exchanger pump 22. After the flow rate is regulated, it enters the breeder salt heat exchanger 9 to remove the heat transferred from the breeder salt. Then, it merges into the main flow path. The mixed cooled molten salt enters the steam generator 23, transfers heat to the energy conversion circuit, and then returns to the main pump 21 of the cooling circuit. In this embodiment, the molten salt cooling circuit 3 adopts a series layout, perfectly matching the natural temperature gradient between the fuel salt (high-temperature heat source) and the breeder salt (relatively low-temperature heat source). The cooling molten salt first absorbs high-temperature heat in the fuel salt heat exchanger 7, rapidly raising its temperature to near the fuel salt outlet temperature. Subsequently, a portion of the cooling molten salt enters the breeder salt heat exchanger 9 to absorb low-temperature heat. This "high-to-low" heat absorption sequence ensures that the high-temperature heat is utilized preferentially, resulting in the cooling molten salt transferred to the triple-loop steam generator 23 having the highest possible average temperature, thereby improving steam parameters and thermodynamic cycle efficiency and reducing heat loss. Furthermore, through the independent and precise adjustment of the branch flow rate by the first breeder salt heat exchange pump 22, the heat exchange capacity of the breeder salt heat exchanger 9 can be precisely controlled, thus flexibly controlling the operating temperature of the breeder salt circuit. This allows the breeder salt temperature to be optimized within the range most suitable for thorium-232 conversion (e.g., improving the conversion rate) or most beneficial for long-term equipment operation without affecting the safety of fuel salt cooling.

[0044] Figure 4 This is a schematic diagram of a two-loop system employing a parallel structure according to an embodiment of this application. Figure 1 In contrast, the molten salt cooling circuit 3 in this embodiment is configured in parallel. The outlet of the main pump 21 of the cooling circuit is connected to a flow path distribution node; from this node, the molten salt is divided into independent fuel salt cooling branches and breeder salt cooling branches; the fuel salt cooling branch is connected to the inlet of the fuel salt heat exchanger 7 via a fuel salt heat exchange pump 33, and the breeder salt cooling branch is connected to the inlet of the breeder salt heat exchanger 9 via a second breeder salt heat exchange pump 32; the outlet of the fuel salt heat exchanger 7 and the outlet of the breeder salt heat exchanger 9 merge and are then connected to the inlet of the steam generator 23. Figure 4As shown, in this embodiment, after passing through the fuel molten salt pump 6, the fuel salt enters the fuel salt heat exchanger 7, transferring heat to the secondary loop cooling molten salt, and then flows out of the heat exchanger and returns to the fuel salt loop 1 via a pipeline; after passing through the breeding molten salt pump 8, the breeding salt enters the breeding salt heat exchanger 9, transferring heat to the secondary loop cooling molten salt, and then flows out of the heat exchanger and returns to the breeding salt loop 2 via a pipeline; after flowing out of the steam generator 23, the secondary loop cooling salt is split, with one part flowing through the second breeding salt heat exchange pump 32, and after flow regulation, entering the breeding salt heat exchanger 9 to remove the heat transferred from the breeding salt, and the other part flowing through the fuel salt heat exchange pump 33, and after flow regulation, entering the fuel salt heat exchanger 7 to remove the heat transferred from the fuel salt, and then the two parts of cooling salt are mixed and enter the steam generator 23.

[0045] In this embodiment, the molten salt cooling circuit 3 adopts a parallel layout. This scheme, by constructing two completely independent cooling branches, provides excellent operational flexibility, control independence, and system scalability for the dual-loop isolated thorium-based molten salt reactor system. The fuel salt cooling branch and the breeder salt cooling branch each have their own independent circulation pumps (fuel salt heat exchange pump 33 and second breeder salt heat exchange pump 32). This means that the cooling flow rates of the two primary loops can be set and adjusted independently and without interference. For example, the flow rate of the fuel salt branch can be significantly increased to enhance its cooling, while the flow rate of the breeder salt branch can be decreased to increase its outlet temperature, without affecting each other. The two branches are hydrodynamically isolated. If a leak, pump failure, or heat exchanger blockage occurs in either branch, the fault is strictly limited to that branch and will not directly affect the normal operation of the other branch.

[0046] Figure 5 This is a schematic diagram of a two-loop system with an integrated structure according to an embodiment of this application. Figure 5 As shown, in this embodiment, the fuel salt heat exchanger and the breeder salt heat exchanger are integrated into a single integrated heat exchanger 31. The fuel salt from the fuel salt circuit 1 flows through a first independent channel within the integrated heat exchanger 31, the breeder salt from the breeder salt circuit 2 flows through a second independent channel within the integrated heat exchanger 31, and the cooling molten salt from the molten salt cooling circuit 3 flows through a common heat transfer zone of the integrated heat exchanger 31, thereby simultaneously removing heat from both the fuel salt and the breeder salt. Figure 3As shown, after passing through the fuel molten salt pump 6, the fuel salt enters the fuel salt pipeline side of the integrated heat exchanger 31, transferring heat to the secondary loop cooling molten salt on the shell side of the integrated heat exchanger. Then, it flows out of the heat exchanger and returns to the fuel salt loop 1 through the pipeline. After passing through the breeding molten salt pump 8, the breeding salt enters the breeding salt pipeline side of the integrated heat exchanger, transferring heat to the secondary loop cooling molten salt on the shell side of the integrated heat exchanger. Then, it flows out of the heat exchanger and returns to the breeding salt loop 2 through the pipeline. After passing through the cooling loop main pump 21, the secondary loop cooling salt enters the shell side of the integrated heat exchanger, simultaneously carrying away the heat transferred from the fuel salt and the breeding salt, and then enters the steam generator 23.

[0047] In this embodiment, the fuel salt heat exchanger and the breeder salt heat exchanger are integrated into a single, unified heat exchanger, significantly reducing piping, valves, and support structures, resulting in a more compact system, lower cost, and fewer potential leakage points. The cooling molten salt absorbs heat from both streams simultaneously within their shared heat transfer zone, achieving efficient thermal integration and management. More importantly, the fuel salt and breeder salt remain completely isolated within the equipment via independent physical channels, fundamentally eliminating the risk of cross-contamination and simplifying maintenance procedures. This makes it a preferred solution for system simplification and enhanced safety.

[0048] like Figure 1 As shown, the three-loop system is energy conversion loop 4. Energy conversion loop 4 includes a steam generator 23 and an energy conversion device (such as a generator). The energy conversion device utilizes the steam generated by the steam generator 23 for comprehensive nuclear energy utilization, such as power generation, heating, steam supply, power supply for the equipment, and seawater desalination.

[0049] This application also provides a method for operating a thorium-based molten salt reactor system, including the following modes: Production mode: The reactor is operated by loading low-enriched uranium as start-up fuel into the fuel salt loop 1, while uranium-233 is produced and accumulated using the breeder salt loop 2. Self-sustaining mode: When the accumulated uranium-233 reaches a predetermined threshold, the start-up fuel is replaced with uranium-233, and the reactor operates in a state where it relies solely on the uranium-233 generated by its own conversion to maintain criticality.

[0050] Figure 6 This is a schematic diagram illustrating the operation method of a thorium-based molten salt reactor system according to an embodiment of this application. In this embodiment, the operation of a reactor is divided into two stages: Production mode: The initial fuel for the reactor is low-enriched uranium (such as fuel salt containing uranium-235). After startup, it generates electricity and continuously produces uranium-233 using a breeder salt circuit, which is then stored in storage tank 30.

[0051] Self-sustaining mode: When the amount of uranium-233 accumulated in storage tank 30 reaches a predetermined threshold (sufficient to start and sustain a reactor operation), the reactor is shut down and the start-up fuel in the fuel salt circuit is replaced with uranium-233 fuel. After restarting, the reactor enters self-sustaining mode, and the uranium-233 consumed during its operation is replenished by uranium-233 produced by its own breeder salt circuit, without the need for external addition of new fissile fuel.

[0052] Figure 7 This is a schematic diagram of the operation method of a thorium-based molten salt reactor system according to another embodiment of this application. In this embodiment, a multi-reactor collaborative strategy can be adopted to accelerate uranium-233 accumulation and large-scale deployment of the power plant: Simultaneously construct and operate at least two reactors (Reactor A and Reactor B), both in production mode as "fuel production reactors," rapidly accumulating uranium-233 together. When the total accumulated uranium-233 is sufficient to start a new reactor, this uranium-233 is used as fuel to start a third reactor (Reactor C), operating directly in self-sustaining mode. Reactors A and B continue to operate in production mode, using their subsequent uranium-233 production to start a fourth, fifth, and so on, all subsequent new reactors (Reactor D, etc.). These new reactors all start and operate directly in self-sustaining mode. This model significantly shortens the time from the construction of the first reactor to achieving a multi-reactor self-sustaining power grid, offering significant engineering and economic advantages.

[0053] This application adopts a two-stage collaborative architecture: in the early stage, it operates in a "production mode" using low-enriched uranium (U-235) as fuel to accumulate uranium-233; in the later stage, it operates in a "self-sustaining mode" using the produced uranium-233 to achieve the goal of 100% thorium energy contribution rate and realize a fully self-sustaining thorium-uranium fuel cycle. Both modes use the same reactor, only the fuel is different.

[0054] This application discloses a thorium-based molten salt reactor system and its operation method that isolates fuel salt and breeder salt. By arranging uranium-233-containing fuel salt and Th-232-containing breeder salt in separate loops, physical isolation between the two is achieved. This design effectively avoids the problem of high mixing of multiple nuclides in traditional liquid fuel molten salt reactors, ensuring that the fuel salt does not contain thorium and eliminating the need for protactinium-233 extraction, thus significantly simplifying the fission product removal process. At the same time, the breeder salt contains almost no fission products, requiring only focus on the extraction of protactinium-233 and uranium-233, significantly reducing the complexity and technical difficulty of chemical reprocessing, and improving the safety and sustainability of system operation.

[0055] Optionally, the fuel tube and solid graphite moderator are integrated into a single modular fuel assembly. The fuel salt undergoes fission and heat generation within the silicon carbide tube, and neutrons penetrate the tube wall into the graphite moderation region, driving a conversion reaction of thorium-232 in the surrounding breeder salt. This structure not only enhances neutron coupling efficiency but also optimizes power distribution and moderation performance, improving the overall thermal safety and neutron economy of the reactor, providing structural assurance for achieving efficient breeder operations.

[0056] Flowcharts are used in this application to illustrate the operations performed by the system according to embodiments of this application. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, various steps can be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more steps may be removed from these processes.

[0057] Obviously, the accompanying drawings described above are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without any inventive effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0058] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not specifically singular and may include plural forms. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0059] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0060] In the description of this application, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0061] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0062] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. In addition, although the terminology used in this application is selected from commonly known and used terms, some terms mentioned in this application's specification may have been chosen by the applicant according to his or her judgment, and their detailed meanings are explained in the relevant sections of this description. Moreover, this application should be understood not only through the actual terms used, but also through the meaning implied by each term.

[0063] The basic concepts have been described above. Obviously, for those skilled in the art, the above disclosure is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0064] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0065] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of the application requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of the single embodiments disclosed above.

[0066] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of scope in some embodiments of this application are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

[0067] Although this application has been described with reference to specific embodiments, those skilled in the art should recognize that the above embodiments are only used to illustrate this application, and various equivalent changes or substitutions can be made without departing from the spirit of this application. Therefore, any changes or modifications to the above embodiments within the essential spirit of this application will fall within the scope of the claims of this application.

Claims

1. A thorium-based molten salt reactor system with fuel salt and breeder salt isolated, characterized in that, include: The primary loop system includes a reactor body (5), a fuel salt loop (1), fuel salt circulating in the fuel salt loop, a breeder salt loop (2), and breeder salt circulating in the breeder salt loop. The fuel salt contains uranium-233 but does not contain thorium-232, and the breeder salt contains thorium-232 but does not contain fissile nuclear fuel. The fuel salt loop (1) and the breeder salt loop (2) are physically isolated within the reactor body (5) and neutronically coupled. The reactor body (5) includes a main container and multiple fuel assemblies disposed therein. Each fuel assembly includes a fuel tube (10) made of insulating material. The two ends of the fuel tube (10) are respectively sealed to the lower chamber (11) and the upper chamber (12) in the main container. The fuel tube (10) is wrapped with a moderator block (13), and a flow channel is formed between the moderator blocks (13). The fuel salt of the fuel salt circuit (1) flows through the inside of the fuel tube (10), and the breeding salt of the breeding salt circuit (2) flows through the flow channel between the moderator blocks (13).

2. The system as described in claim 1, characterized in that, In the axial end regions of the fuel pipe (10), the thickness of the moderator block (13) decreases, forming an axial transition zone (14).

3. The system as described in claim 1, characterized in that, The fuel pipe (10) is made of silicon carbide or metal.

4. The system as described in claim 1, characterized in that, The operating pressure of the breeding salt circuit (2) is configured to be higher than that of the fuel salt circuit (1).

5. The system as described in claim 1, characterized in that, Also includes: A fuel salt processing system (17) is connected to the fuel salt circuit (1) for removing fission products and secondary actinides from the fuel salt; A breeding salt processing system (20) is connected to the breeding salt circuit (2) for extracting protactinium-233 and uranium-233 generated from the breeding salt.

6. The system as described in claim 5, characterized in that, The fuel salt processing system (17) includes a degassing unit (24), a fluorination volatilization unit (25), a vacuum distillation unit (27), and a fuel salt reconstitution unit (26). The inlet of the degassing device (24) is connected to the fuel salt circuit (1), and the outlet of the degassing device (24) is connected to the inlet of the fluorination volatilization device (25). The fluorination volatilization device (25) is provided with a uranium outlet and a deuranium salt outlet. The uranium outlet is used to output the extracted uranium and is connected to the fuel salt reconstruction device (26). The deuranium salt outlet is connected to the inlet of the vacuum distillation device (27), and the outlet of the vacuum distillation device (27) is connected to the fuel salt reconstruction device (26). The outlet of the fuel salt reconstruction device (26) is connected to the fuel salt circuit (1).

7. The system as described in claim 5, characterized in that, The amplified salt treatment system (20) includes a reduction extraction device (28), a back extraction device (29), and a storage tank (30). The inlet of the reduction extraction device (28) is connected to the breeding salt circuit (2) for extracting protactinium-233 and uranium-233, and is provided with a purified salt outlet and an extraction phase outlet. The purified salt outlet is used to return the extracted purified breeding salt to the breeding salt circuit (2). The extraction phase outlet is connected to the inlet of the back extraction device (29). The back extraction device (29) is used to convert the extracted protactinium-233 and uranium-233 into a molten salt containing protactinium-233 and uranium-233, and output it to the storage tank (30) for storage.

8. The system as described in claim 1, characterized in that, Also includes: The molten salt cooling circuit (3) includes a cooling circuit main pump (21), a fuel salt heat exchanger (7), a breeding salt heat exchanger (9), a steam generator (23), and cooling molten salt circulating in the molten salt cooling circuit (3), the cooling molten salt being configured to absorb the heat transferred by the fuel salt circuit (1) and the breeding salt circuit (2) and output the heat to the energy conversion circuit (4). Energy conversion circuit (4) is used to convert the heat into electrical energy.

9. The system as described in claim 8, characterized in that, The molten salt cooling circuit (3) is configured in series: the outlet of the main pump (21) of the cooling circuit is connected to the inlet of the fuel salt heat exchanger (7), the outlet of the fuel salt heat exchanger (7) is divided into a main path and a regulating branch, the main path is connected to the inlet of the steam generator (23), the regulating branch is connected to the inlet of the breeding salt heat exchanger (9) via the first breeding salt heat exchange pump (22), and the outlet of the breeding salt heat exchanger (9) merges with the pipeline leading to the steam generator (23).

10. The system as described in claim 8, characterized in that, The molten salt cooling circuit (3) is configured in parallel: the outlet of the main pump (21) of the cooling circuit is connected to a flow distribution node; from this node, the molten salt is divided into a fuel salt cooling branch and a breeding salt cooling branch that are independent of each other; the fuel salt cooling branch is connected to the inlet of the fuel salt heat exchanger (7) via a fuel salt heat exchange pump (33), and the breeding salt cooling branch is connected to the inlet of the breeding salt heat exchanger (9) via a second breeding salt heat exchange pump (32); the outlet of the fuel salt heat exchanger (7) and the outlet of the breeding salt heat exchanger (9) merge and are then connected to the inlet of the steam generator (23).

11. The system as described in claim 8, characterized in that, The fuel salt heat exchanger (7) and the breeder salt heat exchanger (9) are integrated into a single integrated heat exchanger (31). The fuel salt in the fuel salt circuit (1) flows through the first independent channel in the integrated heat exchanger (31), the breeding salt in the breeding salt circuit (2) flows through the second independent channel in the integrated heat exchanger (31), and the cooling molten salt in the molten salt cooling circuit (3) flows through the common heat transfer zone of the integrated heat exchanger (31) to simultaneously remove heat from the fuel salt and the breeding salt.

12. A method for operating a thorium-based molten salt reactor system according to any one of claims 1 to 11, characterized in that, Includes the following modes: Production mode: The reactor is operated by loading low-enriched uranium as start-up fuel into the fuel salt circuit (1), while the breeder salt circuit (2) is used to produce and accumulate uranium-233. Self-sustaining mode: When the accumulated uranium-233 reaches a predetermined threshold, the start-up fuel is replaced with uranium-233, and the reactor operates in a state where it relies solely on the uranium-233 generated by its own conversion to maintain criticality.

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