Molten salt reactor and molten salt reactor system

Abstract

Provided is a molten salt reactor comprising: a reactor vessel; and a containment vessel surrounding the reactor vessel, wherein an inert salt is provided outside the reactor vessel and inside the containment vessel, and the inert salt is a liquid phase or a solid phase.

Description

Molten salt reactors and molten salt reactor systems

[0001] The present invention relates to a molten salt reactor and a molten salt reactor system, and more particularly, to a molten salt reactor and a molten salt reactor system that enable multipurpose, long-period, long-life operation with a single system.

[0002]

[0003] Molten salt reactors (MSRs) differ from commercial light water reactors that utilize solid nuclear fuel. Their fuel, along with the coolant salt, melts and flows through the reactor system in a liquid state. Consequently, molten salt reactors possess inherently superior safety characteristics, including a strong negative feedback effect due to relatively large thermal expansion and a large safety margin even at low pressures. In particular, molten salt reactors possess a high boiling point in low-pressure or non-pressurized environments, enabling high-temperature operation due to their high safety margin, which in turn leads to superior productivity.

[0004] Molten salt reactors typically operate at temperatures between 600 and 750°C. This allows them to achieve high hydrogen production efficiency through high-temperature water electrolysis. Furthermore, molten salt reactors can be used as a valuable heat source for industrial applications.

[0005] At the 2001 International Forum on Generation IV Nuclear Systems, the molten salt reactor was selected as one of the future reactor technologies. The United States, Japan, China, Denmark, and other countries are actively developing advanced reactor technologies, including large modular, small modular, marine, and land-based reactors, based on the project model developed at Oak Ridge National Laboratory in the 1960s.

[0006] Conventional concepts have been proposed for molten salt reactors, utilizing thorium, low-enriched uranium, spent nuclear fuel, and nuclear weapons fuel. Nuclear fuel materials used in molten salt reactors can be combined in various ways, including double and triple mixtures with chlorides and fluorides. Because molten salt reactor performance varies depending on the fuel mixture ratio, various molten salt reactor concepts have been proposed.

[0007] For example, Korean Patent Registration Publication No. 10-1717942 discloses a nuclear fuel assembly including a plurality of nuclear fuel bodies for causing a nuclear fission chain reaction, a molten salt coolant disposed between the nuclear fuel bodies to absorb energy released by the nuclear fission chain reaction and including a molten salt component, and a reflector disposed to surround the outer wall of the nuclear fuel assembly to reduce external leakage of neutrons generated from the nuclear fuel assembly, wherein the molten salt coolant includes a nuclear fuel component of LiF-BeF2-ThF4-UF4, wherein the LiF is 15 to 25 parts by weight, the BeF2 is 3 to 13 parts by weight, the ThF4 is 31 to 41 parts by weight, and the UF4 is 31 to 41 parts by weight, and the core is designed to be set to a critical state in which an effective multiplication factor is 1 or more by the molten salt coolant including the nuclear fuel components in a subcritical state, and when a loss of coolant accident occurs in the critical state, the molten salt coolant A reactor is described comprising a small modular reactor core designed to be set in a subcritical state with an effective multiplication factor less than 1 as coolant leaks.

[0008] Molten salt reactors are expected to be commercialized in the relatively near future, and demonstration experiments are currently being conducted in some countries.

[0009] Molten salt reactors currently under commercialization and demonstration include the Seaborg Floating Molten Salt Reactor (MSR) from Denmark, the IMSR from Terrestrial Energy in Canada, and the TMSR from China. These candidates for these molten salt reactor systems are thorium reactors utilizing the thorium-uranium (Th-U) fuel cycle, which utilizes nuclear fission in the thermal neutron spectrum. Conversely, the concept of a molten salt fast reactor utilizing the fast neutron spectrum is also being proposed due to its advantages in breeding efficiency and radioactive waste reduction. Examples include the Molten Chloride Fast Reactor (MCFR) from TerraPower in the United States and the Molten Salt Fast Reactor (MSFR) from CNRS in France.

[0010] However, conventional molten salt reactors can achieve high safety and productivity due to the characteristic of nuclear fuel flowing through the reactor system in the form of molten salt together with coolant salt, but a method is required to overcome the problems described below.

[0011] A primary problem with prior art is that, since nuclear fission occurs in the core region containing the fuel material, such as thorium or uranium, other nuclides or fission products resulting from the nuclear reaction may be generated within the fuel-coolant molten salt. Utilizing thermal neutron spectra requires real-time reprocessing, which may violate the Nuclear Non-Proliferation Treaty. Furthermore, utilizing fast neutron spectra can also generate insoluble fission products, which can compromise the physical stability of the reactor. Furthermore, if fission products are adsorbed on certain structures, such as intermediate heat exchangers, this can significantly reduce local thermal-hydraulic performance and deteriorate material integrity.

[0012] A second problem with conventional technologies lies in the difficulty in applying molten salt circulation pumps to the reactor system, which is characterized by high temperatures, high radiation, and high corrosiveness. High-temperature molten salt can be highly corrosive to metals, and the presence of nuclear materials and fission products can create a highly radioactive environment. Consequently, the circulation pumps typically used in the nuclear power industry may struggle to ensure long-term operation. A deterioration or failure of the circulation pump not only degrades reactor performance but can also trigger a nuclear accident due to abrupt transitions. Furthermore, radioactive materials can leak through the circulation pump's connections. Therefore, developing circulation pumps for molten salt reactors can be a significant technical challenge and incur high costs.

[0013] A third problem with prior art is that, when applying slow-speed spectrum, graphite is used as a moderator within the reactor, but its lifespan is short compared to the lifespan of the reactor. This means that graphite is a high-level radioactive waste. Furthermore, graphite must be manufactured in rod form and installed in multiple cores, which can hinder molten salt circulation and thus require high-performance pumps. When applying fast-speed spectrum, a device for controlling the nuclear reactivity within the core is essential, making implementation technically challenging. In other words, while a device for controlling nuclear reactivity is required, such a device can create flow and impede circulation, potentially degrading the performance of the molten salt reactor. Consequently, a method for significantly reducing the use of graphite moderators is urgently needed.

[0014] A fourth problem with conventional technology is that while molten salt reactors can significantly reduce radioactive waste compared to existing commercial light water reactors, significant radioactive waste is generated in the low-speed spectrum, even without a graphite moderator, if high core burnup is not achieved. Furthermore, the high radioactive waste generated relative to burnup and the need for frequent refueling hinder economic viability. Consequently, achieving high burnup is a pressing need.

[0015] A fifth problem with conventional technology is that decay heat continues to be generated even after the reactor is shut down normally during abnormal operation or an accident. Molten salt reactors can have a long response time due to their inherent safety and high safety margins. However, if decay heat cannot be sufficiently removed and cooling performance cannot be guaranteed, boiling of the molten salt can occur. This can lead to increased radioactive material leakage. Therefore, many molten salt reactors utilize freeze plugs and emergency vent tanks, along with key safety systems that actively or passively vent and cool the fuel-coolant molten salt. However, this requires one or more additional penetrations in the lower part of the reactor vessel and can require excessive lower installation space relative to the power output. Consequently, a molten salt reactor system capable of continuously and safely removing decay heat is needed.

[0016] The sixth problem with conventional technology lies in the fact that materials within the reactor system, such as the reactor vessel and intermediate heat exchanger, are constantly exposed to high temperatures, high radiation, and highly corrosive environments. Even when structural integrity, such as mechanical strength, is maintained, corrosion and deterioration can lead to the generation of unintended chemical compounds through chemical reactions within the reactor system. Alternatively, material corrosion and deterioration can persist locally, potentially compromising material integrity. In other words, corrosion-resistant materials are needed to minimize the effects of these compounds and ensure material integrity.

[0017]

[0018] The technical problem to be solved by the present invention is to provide a molten salt reactor and a molten salt reactor system capable of separating insoluble fission products without circulating them within a reactor system including a core and an intermediate heat exchanger during normal operation, i.e., capable of removing insoluble fission product gas, noble metals, etc.

[0019] Another technical problem to be solved by the present invention is to provide a molten salt reactor and a molten salt reactor system that can form stable circulation and operate normally even when a circulation pump is removed from the reactor system.

[0020] Another technical problem to be solved by the present invention is to provide a molten salt reactor and a molten salt reactor system that can improve circulation performance and maintain a stable state by including it in an operating logic circuit.

[0021] Another technical problem to be solved by the present invention is to provide a molten salt reactor and a molten salt reactor system that reduce factors that may interfere with circulation in a system excluding a circulation pump and include a core control technology with excellent performance.

[0022] Another technical problem that the present invention seeks to solve is to provide a molten salt reactor and a molten salt reactor system that can achieve a long lifespan by enabling long-term stable operation.

[0023] Another technical problem that the present invention seeks to solve is to provide a molten salt reactor and a molten salt reactor system that can safely remove decay heat without releasing radioactive materials into the environment even if abnormal operation or an accident occurs.

[0024] Another technical problem to be solved by the present invention is to provide a molten salt reactor and a molten salt reactor system in which a base material, coating material, or corrosion-resistant material technique is applied to structural materials applied to reactor vessels, intermediate heat exchangers, etc., to reduce long-term corrosion of the base material and maintain long-term material soundness.

[0025] Another technical problem to be solved by the present invention is to provide a molten salt reactor and a molten salt reactor system that can be practically used for multiple purposes and can be connected to systems requiring low-carbon, high-temperature heat sources, such as power generation, district heating, seawater desalination, hydrogen production, and process heat sources.

[0026] The technical problems to be solved by the present invention are not limited to those described above.

[0027]

[0028] To solve the above technical problem, the present invention provides a molten salt reactor.

[0029] According to one embodiment, the molten salt reactor comprises a reactor vessel and a containment vessel surrounding the reactor vessel, and includes an inert salt provided on the outside of the reactor vessel and on the inside of the containment vessel, wherein the inert salt may be in a liquid or solid state.

[0030] According to one embodiment, the reactor system is included within the reactor vessel, the reactor system including at least one unit among a reactor core, a riser, an intermediate heat exchanger high-temperature side, or a downcomer, wherein a heat production mechanism of the core may include nuclear fission by a fast neutron spectrum.

[0031] According to one embodiment, the containment vessel has a temperature inside that decreases as it gets farther away from the center in a radial direction, and the inert salt inside the containment vessel forms a solid layer of insulating properties on the inner wall of the containment vessel, but is converted into a liquid phase when an accident occurs, and the inert salt dilutes the nuclear fuel-coolant salt when discharged from the reactor vessel, and is selected from the group consisting of sodium chloride-magnesium chloride (NaCl-MgCl2), lithium chloride-potassium chloride (LiCl-KCl), lithium chloride-rubidium chloride (LiCl-RbCl), potassium chloride-magnesium chloride (KCl-MgCl2), sodium chloride-potassium chloride-magnesium chloride (NaCl-KCl-MgCl2), lithium chloride-potassium chloride-magnesium chloride (LiCl-KCl-MgCl2), potassium fluoride-zirconium fluoride (KF-ZrF4), sodium fluoride-sodium fluoroborate (NaF-NaBF4), Potassium fluoride-potassium fluoroborate (KF-KBF4), rubidium fluoride-rubidium fluoroborate (RbF-RbBF4), or lithium fluoride-sodium fluoride-potassium fluoride (LiF-NaF-KF) can be used in thermal energy storage devices.

[0032] According to one embodiment, the reactor vessel comprises a helium injection unit provided at the lower portion or the upper portion and injecting helium into the reactor vessel, and an off-gas system provided at the upper portion of the reactor vessel and discharging helium inside the reactor vessel, wherein the off-gas system can discharge at least one of helium, gas, and volatile fission products injected through the helium injection unit.

[0033] According to one embodiment, the reactor system includes a drum-type reactivity controller inside the reactor system and outside the core, wherein the drum-type reactivity controller controls the circulation and reactivity of the reactor system while not interfering with the flow in the core and the riser, and can be operated in a direction to passively or actively suppress nuclear fission according to a power cut.

[0034] According to one embodiment, the circulation and reactivity of the reactor system can be controlled by using the amount of helium injected from the helium injection unit or the rotation of the drum-type reactivity controller as control variables.

[0035] According to one embodiment, the control of the circulation and reactivity of the reactor system may include at least one of a first control for rotating at least some of the absorbent pads of the drum-type reactivity controller toward the core, or a second control for maintaining the injection amount of helium provided from the helium injection unit to increase or decrease for a predetermined period of time.

[0036] According to one embodiment, the upper part of the reactor vessel or the intermediate heat exchanger comprises a prefabricated part provided for removal, mounting, installation, inspection, or replacement, wherein the intermediate heat exchanger may be a shell and helical-coil tube heat exchanger or a printed circuit heat exchanger.

[0037] According to one embodiment, the apparatus comprises an inlet for introducing outside air into the containment vessel, and an outlet for discharging air inside the containment vessel to the outside, wherein the inlet and the outlet are closed during normal operation and open passively or actively according to a power cut, and the outlet may be higher in height from the bottom surface of the containment vessel than the inlet.

[0038] According to one embodiment, the molten salt reactor includes a structure having corrosion resistance and soundness at a molten salt contact surface inside the reactor vessel and the containment vessel, and the inside of the reactor vessel is operated at a low pressure of less than 10 atm, and the molten salt reactor includes nuclear fuel provided inside the reactor vessel, wherein the nuclear fuel may be low enriched uranium (LEU) having an enrichment degree of uranium-235 of less than 20%.

[0039] According to one embodiment, the working fluid of the reactor system comprises a molten salt, wherein the molten salt comprises sodium chloride-uranium trichloride (NaCl-UCl3) or potassium chloride-uranium trichloride (KCl-UCl3) or an actinide, and in an upper space of the reactor vessel where the molten salt is not present, a gas that is chemically non-reactive with the molten salt, wherein the chemically non-reactive gas may comprise at least one of helium (He), argon (Ar), krypton (Kr), xenon (Xe), carbon dioxide (CO2), or nitrogen (N2).

[0040] In one embodiment, the core is capable of long-life operation of 20 years or more, without performing on-line reprocessing and without additional nuclear fuel injection.

[0041]

[0042] To solve the above technical problem, the present invention provides a molten salt reactor system.

[0043] According to one embodiment, in a molten salt reactor system including the molten salt reactor, the molten salt reactor system may further include a thermal energy storage system that receives heat from a reactor system and supplies thermal energy to a production system, wherein the thermal energy storage system may include an intermediate heat exchanger low-temperature side that receives heat from a high-temperature side of an intermediate heat exchanger of the reactor system inside the reactor vessel, a thermal energy storage tank in which molten salt heated while passing through the intermediate heat exchanger low-temperature side is moved and thermal energy is stored, and a production heat exchanger that transmits the thermal energy to a user requiring a high-temperature heat source.

[0044] According to one embodiment, the thermal energy storage system comprises an inert salt that does not contain nuclear material, wherein the inert salt is sodium chloride-magnesium chloride (NaCl-MgCl2), lithium chloride-potassium chloride (LiCl-KCl), lithium chloride-rubidium chloride (LiCl-RbCl), potassium chloride-magnesium chloride (KCl-MgCl2), sodium chloride-potassium chloride-magnesium chloride (NaCl-KCl-MgCl2), lithium chloride-potassium chloride-magnesium chloride (LiCl-KCl-MgCl2), potassium fluoride-zirconium fluoride (KF-ZrF4), sodium fluoride-sodium fluoroborate (NaF-NaBF4), potassium fluoride-potassium fluoroborate (KF-KBF4), rubidium fluoride-rubidium fluoroborate (RbF-RbBF4), or Lithium fluoride-sodium fluoride-potassium fluoride (LiF-NaF-KF) can be used in thermal energy storage devices.

[0045] According to one embodiment, the molten salt reactor system is configured such that the flow within the thermal energy storage system is regulated according to energy demand, and the thermal energy can be supplied from the thermal energy storage system to the production system through the production heat exchanger.

[0046] In one embodiment, the application may include at least one of power generation, district heating, seawater desalination, hydrogen production, or process heat source, which require a high temperature heat source.

[0047]

[0048] To solve the above technical problem, the present invention provides a molten salt reactor structure.

[0049] According to one embodiment, the molten salt reactor structure may include the molten salt reactor, wherein the surrounding environment of the molten salt reactor is at a pressure below atmospheric pressure and is an atmospheric atmosphere, and wherein the pressure below atmospheric pressure is non-pressurized.

[0050] In one embodiment, the molten salt reactor system can provide high power without using a neutron spectrum, chlorine salt, or pump.

[0051] According to one embodiment, the molten salt reactor system can inject helium in the form of bubbles from the bottom surface of the lower part of the reactor vessel or from the core outlet or the rising part. As the helium is injected in the form of bubbles, insoluble fission products, mainly gases or precious metals, can be absorbed into the helium bubbles or adsorbed on the surface and moved to the upper interface. When the bubbles burst at the interface, the insoluble fission products are guided by the first guide part and the second guide part of the present application and are contained in a specific space, thereby providing an effect of easy management.

[0052] According to one embodiment, the molten salt reactor system has a relatively high density of the working fluid of the molten salt reactor, resulting in a large pressure drop, but a very large temperature difference of 100 to 150°C at the inlet and outlet of the core, so that buoyancy due to the large density difference can be expected. In addition, additional driving force can be obtained by injecting helium gas. However, the height may be increased to achieve high output. Accordingly, the molten salt reactor system can form circulation even without excluding the circulation pump from the reactor system.

[0053] According to one embodiment, the molten salt reactor system can be configured such that circulation within the reactor system is induced by helium injection and natural circulation due to temperature changes. Since the working fluid within the reactor system is a nuclear fuel-coolant molten salt mixture, circulation can significantly affect the reactor's physical and thermal output. Accordingly, the helium injection amount can be measured using temperature and flow rate information, and the helium injection amount can be used as a control variable to maintain reactivity and the reactor's physical and thermal-hydraulic normal operating range. Furthermore, this can be incorporated into the operating logic circuit to maintain a stable normal operating state.

[0054] According to one embodiment, the molten salt reactor system can utilize the fast neutron spectrum, thereby eliminating the need for a graphite moderator and simplifying the core structure. However, a separate device may be required for reactivity control. To address this, according to the present application, the molten salt reactor system may include a drum-type reactivity controller installed outside the core. This eliminates the core pressure drop factor and ensures excellent core control performance.

[0055] In one embodiment, the molten salt reactor system may use sodium chloride-uranium trichloride (NaCl-UCl3) or potassium chloride-uranium trichloride (KCl-UCl3) as a working fluid within the reactor system. More specifically, sodium chloride:uranium trichloride (NaCl:UCl3) may be used in a molar ratio of 67:33, and potassium chloride:uranium trichloride (KCl:UCl3) may be used in a molar ratio of 47:53. However, the present invention is not limited thereto, and the mass ratios described above may vary depending on design and operating conditions and operating periods.

[0056] According to one embodiment, the molten salt reactor system may include a reactor vessel in which a working fluid circulates, an inert liquid salt layer and an outermost solid layer surrounding the outside of the reactor vessel, a containment vessel surrounding the reactor vessel, and an outside air system that passively opens and closes to allow outside air to flow into the outer wall of the containment vessel to cool it in the event of an accident, as a passive safety system. The outside air serves as the final heat sink, thereby safely removing decay heat.

[0057] According to one embodiment, the molten salt reactor system may utilize a metal material having a high nickel (Ni) content, which has a low chromium (Cr) content and high corrosion resistance in chlorine-based molten salts, as a base material. In addition, to prevent corrosion of the base material, a large-area coating technique may be used to coat the base material with a material such as zirconium nitride (ZrN), chromium oxide (Cr2O3), or yttrium oxide (Y2O3), thereby enhancing corrosion resistance.

[0058] According to one embodiment, the molten salt reactor system may include a reactor vessel enclosing a reactor system (primary system) including a core, an ascending section, an intermediate heat exchanger high temperature side, or a descending section, a reactor module including a containment vessel filled with liquid and solid inert salts existing outside the reactor vessel, a thermal energy storage system (secondary system) including an intermediate heat exchanger tube side, a thermal energy storage, a production heat exchanger for transferring heat from the thermal energy storage to a tertiary system used for production such as electric power generation, district heating, seawater desalination, hydrogen production, and process heat sources, and a production system (tertiary system) including equipment necessary for production. Thermal energy may be stored in the thermal energy storage of the secondary system in the reactor system so that the production system can supply energy as needed and use it for production. Accordingly, load-following operation and operational flexibility can be secured, and tritium and radioactive materials that may be generated in the reactor system can be completely separated from the production system. Furthermore, since a separate accumulator is installed in the thermal energy storage system and there are no separate restrictions on the production system, it can be utilized for multiple purposes.

[0059]

[0060] According to an embodiment of the present invention, a molten salt reactor and a molten salt reactor system including the molten salt reactor may be provided, the molten salt reactor including a reactor vessel and a containment vessel surrounding the reactor vessel, wherein the molten salt includes an inert salt provided on the outside of the reactor vessel and an inside of the containment vessel, the inert salt including a liquid or solid state.

[0061] According to an embodiment of the present application, the molten salt reactor system can have a simplified system structure. More specifically, the molten salt reactor system can have a simplified system structure by eliminating the reactor system circulation pump. Furthermore, the molten salt reactor system can have a simplified system structure by eliminating the freeze plug and the emergency drain tank, thereby reducing the height of the system structure and eliminating the connecting parts. In other words, since the molten salt reactor system can have a simplified system structure, the manufacturability can be improved, the application of a passive safety system can be advantageous, and the reliability of the system can be increased.

[0062] According to embodiments of the present application, the molten salt reactor system can reduce radioactive waste. Because the molten salt reactor system utilizes a fast spectrum, the periodic replacement of graphite moderators can be reduced or eliminated, thereby minimizing high-level radioactive waste. Furthermore, the molten salt reactor system can operate at high burnup, with long cycles and long lifetimes, thereby minimizing radioactive waste.

[0063] According to an embodiment of the present application, the molten salt reactor system can be operated stably. In addition, the molten salt reactor system can minimize physical instability by removing insoluble fission products during normal operation. In addition, the molten salt reactor system can minimize unstable flow and accidents due to malfunction and failure of the circulation pump by utilizing natural circulation. In addition, the molten salt reactor system can maintain stable operating conditions by controlling the amount of helium injected from the helium injection unit. In addition, the molten salt reactor system can increase operational and production flexibility by placing a thermal energy storage system between the reactor system and the production system and dynamically controlling the conditions of the thermal energy storage system.

[0064] According to an embodiment of the present application, the molten salt reactor system can have enhanced safety and improved reliability. The molten salt reactor system can have high safety and improved safety system reliability by applying a passively operating safety system that goes beyond the inherent safety of a molten salt reactor. The molten salt reactor system can maximize site selection flexibility by using the atmosphere (outside air) as the final heat sink. Accordingly, the molten salt reactor system can have improved social acceptance. In particular, since the molten salt reactor system has a very large temperature difference between the system temperature and the atmosphere, it can be applied regardless of climate (tropical, subtropical, temperate, frigid, and polar) through the main heat removal mechanism.

[0065] According to embodiments of the present application, the molten salt reactor system can avoid violations of the Nuclear Non-Proliferation Treaty. The molten salt reactor system can minimize violations of the Nuclear Non-Proliferation Treaty by utilizing low-enriched uranium and a fast spectrum. In particular, since the molten salt reactor system does not undergo chemical processing (online reprocessing) during operation, it can have advantages such as operational convenience, radioactive material management convenience, and system simplification.

[0066] According to embodiments of the present application, the molten salt reactor system can be utilized for multiple purposes. The molten salt reactor system can obtain a high-temperature heat source from a thermal energy storage system and utilize it for various purposes, such as power generation, district heating, seawater desalination, hydrogen production, and process heat source. In other words, the molten salt reactor system can be utilized in various ways as a single system, thereby exhibiting excellent utility value.

[0067]

[0068] FIG. 1 is a drawing for explaining a molten salt reactor according to an embodiment of the present application.

[0069] FIG. 2 is a drawing for explaining in more detail a molten salt reactor according to an embodiment of the present application.

[0070] FIG. 3 is a drawing for explaining a helium injection unit of a molten salt reactor according to an embodiment of the present application.

[0071] FIG. 4 is a drawing for explaining an off-gas system in a molten salt reactor according to an embodiment of the present application.

[0072] FIG. 5 is a drawing for explaining in more detail an off-gas system according to an embodiment of the present application.

[0073] FIG. 6 is a drawing for comparing and explaining an off-gas system according to an embodiment of the present application and a conventional system.

[0074] FIG. 7 is a drawing for explaining a drum-type reaction controller according to an embodiment of the present application.

[0075] FIG. 8 is a drawing for explaining an inert salt of a molten salt reactor according to an embodiment of the present application.

[0076] FIG. 9 is a drawing for explaining the inlet and outlet of a molten salt reactor according to an embodiment of the present application.

[0077] FIG. 10 is a drawing for explaining a molten salt reactor system according to an embodiment of the present application.

[0078] FIG. 11 is a drawing for explaining a control method of a molten salt reactor system according to an embodiment of the present application.

[0079] FIG. 12 is a drawing for explaining a molten salt reactor structure according to an embodiment of the present application.

[0080] Figure 13 is a graph evaluating the possibility of long-period, long-life operation of a molten salt reactor according to an experimental example of the present application through computer analysis.

[0081] Figure 14 is a graph evaluating the safety in the event of an accident in a molten salt reactor according to an experimental example of the present application.

[0082]

[0083] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the technical concept of the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed content is thorough and complete and to sufficiently convey the spirit of the present invention to those skilled in the art.

[0084] In this specification, when a component is referred to as being on another component, it means that the component may be formed directly on the other component, or a third component may be positioned between them. Furthermore, in the drawings, the shapes and thicknesses of regions are exaggerated for the purpose of effectively explaining the technical content.

[0085] Also, although terms such as first, second, and third have been used to describe various components in various embodiments of this specification, these components should not be limited by these terms. These terms are only used to distinguish one component from another. Thus, what is referred to as a first component in one embodiment may be referred to as a second component in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiments. Also, the term "and / or" has been used herein to mean including at least one of the components listed before and after.

[0086] In the specification, singular expressions include plural expressions unless the context clearly dictates otherwise. In addition, terms such as "comprise" or "have" are intended to specify the presence of a feature, number, step, component, or combination thereof described in the specification, and should not be construed as excluding the presence or addition of one or more other features, numbers, steps, components, or combinations thereof. In addition, the term "connection" is used in the present specification to mean both indirectly connecting multiple components and directly connecting them.

[0087] Additionally, terms such as “part,” “unit,” and “module” described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware, software, or a combination of hardware and software.

[0088] In addition, when describing the present invention below, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

[0089]

[0090] FIG. 1 is a drawing for explaining a molten salt reactor according to an embodiment of the present application, FIG. 2 is a drawing for explaining a molten salt reactor according to an embodiment of the present application in more detail, FIG. 3 is a drawing for explaining a helium injection unit of a molten salt reactor according to an embodiment of the present application, FIG. 4 is a drawing for explaining an off-gas system in a molten salt reactor according to an embodiment of the present application, FIG. 5 is a drawing for explaining an off-gas system according to an embodiment of the present application in more detail, FIG. 6 is a drawing for comparing and explaining an off-gas system according to an embodiment of the present application with a conventional system, FIG. 7 is a drawing for explaining a drum-type reactivity controller according to an embodiment of the present application, FIG. 8 is a drawing for explaining an inert salt of a molten salt reactor according to an embodiment of the present application, and FIG. 9 is a drawing for explaining an inlet and an outlet of a molten salt reactor according to an embodiment of the present application.

[0091] Referring to FIG. 1, the molten salt reactor (100) may include a reactor vessel (110).

[0092] According to one embodiment, the upper portion of the reactor vessel (110) may be provided in an assembly form for separation, mounting, installation, inspection, or replacement.

[0093] In addition, the reactor vessel (110) may include a reactor system therein. More specifically, referring to FIG. 2, the reactor system may include at least one unit among a reactor core (111), a riser (112), an intermediate heat exchanger high-temperature side (113), a downcomer (114), a helium injection unit (115), an off-gas system (116), or a drum-type reactivity controller (117). Meanwhile, the reactor system may be transported individually by unit and assembled on site.

[0094] According to one embodiment, the core (111) is provided at the lower portion of the reactor vessel (110), and nuclear fission can occur in the core (111) by a fast neutron spectrum. As a result, heat can be generated in the core (111). According to the present application, the core (111) can be operated for a long period of time of 20 years or more without performing chemical treatment (online-reprocessing) during operation and without additional nuclear fuel injection.

[0095] According to one embodiment, the rising portion (112) may extend from the bottom to the top of the reactor vessel (110). This allows helium or molten salt to flow upward along the rising portion (112).

[0096] According to one embodiment, the intermediate heat exchanger (113) may be provided in an assembly form for separation, mounting, installation, inspection, or replacement. The intermediate heat exchanger (113) may be a shell and helical-coil tube heat exchanger, or a printed circuit heat exchanger, as illustrated in FIG. 2. However, the present invention is not limited thereto. Meanwhile, the reactor vessel (110) may include a high-temperature side of the intermediate heat exchanger (113), but the reactor system (1000, see FIG. 10) including the reactor vessel (110) may include a low-temperature side (intermediate heat exchanger low-temperature side) of the intermediate heat exchanger (113). Due to this, heat can be transferred from the high temperature side of the intermediate heat exchanger (113) of the reactor vessel (110) to the low temperature side of the intermediate heat exchanger (113) of the reactor system (1000).

[0097] According to the present application, the molten salt reactor (100) can allow nuclear fuel to flow together with coolant within the reactor system. According to the present application, a neutron reflector is installed in the core (111), so that a nuclear fission reaction mainly occurs in the core (111) region, and thus thermal energy can be provided to the molten salt. The molten salt heated by the thermal energy supply has a relatively low density, so that buoyancy can act in an upward direction, and thus can move upward. The intermediate heat exchanger (113) can have a height higher from the bottom surface of the molten salt reactor (100) than the core (111). Accordingly, the molten salt heated in the core (111) region can flow along the shell side of the intermediate heat exchanger (113) and be cooled. The molten salt cooled on the shell side of the intermediate heat exchanger (113) can have a relatively high density, and thus can move downward. Therefore, according to the present application, a flow can be formed through natural circulation. That is, according to the present application, circulation can be achieved through the above-described natural circulation even in a reactor system that does not include a circulation pump. At this time, the temperature at the inlet and outlet of the core (111) and the inlet and outlet of the intermediate heat exchanger (113) can be maintained within 600 to 800°C.

[0098] According to one embodiment, the lowering portion (114) may extend from the upper portion to the lower portion of the reactor vessel (110). This allows helium or molten salt to flow downward along the lowering portion (114).

[0099] According to one embodiment, the helium injection unit (115) may be provided at the lower portion of the reactor vessel (110) or at the rising portion (112). Accordingly, helium may be injected into the reactor vessel (110) through the helium injection unit (115). The helium injection unit (115) may be, for example, in the form of a nozzle and may be connected to a gas tank in which helium is stored through a fluid line (126, see FIG. 8). When the helium in the gas tank moves through the fluid line (126) and is provided to the lower portion of the reactor vessel (110) or the rising portion (112) through the helium injection unit (115), a bubble (bl, see FIG. 3) may be formed inside the reactor vessel (110). More specifically, referring to FIG. 3, the bubble (bl) formed through the injected helium can absorb or adsorb on the surface insoluble fission products (fp), such as gases or precious metals, inside the reactor vessel (110). The bubble (bl) that has absorbed or adsorbed the insoluble fission products (fp) can move to the upper part of the reactor vessel (110) through the rising part (112). The bubble (bl) that has moved to the upper part of the reactor vessel (110) can burst on the surface of the molten salt (ms) above the reactor vessel (110). When the bubble (bl) bursts, the insoluble fission products (fp) absorbed or adsorbed by the bubble (bl) can fall.

[0100] At this time, the reactor vessel (110) may include a first guide part (124) and a second guide part (125) for guiding the movement of the insoluble fission product (fp) at the upper portion, as illustrated in FIG. 3. More specifically, the first guide part (124) may include at least one of a first side wall (124a) and a second side wall (124b). More specifically, the first side wall (124a) may be extended upwardly so that the bubble (bl) that has absorbed or adsorbed the insoluble fission product (fp) moves upwardly of the second guide part (125), as illustrated in FIG. 3. Accordingly, the bubble (bl) that has absorbed or adsorbed the insoluble fission product (fp) may move upwardly of the second guide part (125). Meanwhile, as illustrated in FIG. 3, the second side wall (124b) may be bent from one end of the first side wall (124a), and may be extended toward the second guide portion (125) so that when the bubble (bl) that has absorbed or adsorbed the insoluble fission product (fp) moves upward along the first side wall (124a) toward the second guide portion (125) and bursts, the insoluble fission product (fp) falling from the burst bubble (bl) moves upward of the second guide portion (125). Accordingly, when the bubble (bl) that has captured the insoluble fission product (fp) rises along the first side wall (124a) and bursts above the second guide portion (124b), the insoluble fission product (fp) falling from the burst bubble (bl) can move along the second side wall (124b) to the upper side of the second guide portion (125).

[0101] At this time, the second guide part (125) may be extended toward the receiving space (sp) that receives the insoluble fission product (fp), as illustrated in FIG. 3. Accordingly, the insoluble fission product (fp) moved to the upper side of the second guide part (125) may move along the second guide part (125) and settle in the receiving space (sp). That is, according to the present application, since the insoluble fission product (fp) is received in a specific space, there is an effect of making it easy to collect and manage the insoluble fission product (fp) in the specific space.

[0102] That is, in the molten salt reactor (100), since the nuclear fuel-coolant molten salt is in a eutectic mixture, products generated by nuclear fission or other nuclear reactions may exist in the molten salt, and the products may flow within the reactor system. Among these, the insoluble fission products that do not dissolve and exist in a gaseous or solid state may cause physical instability. In addition, the insoluble fission products may deteriorate thermal-hydraulic performance and material integrity. However, according to the embodiment of the present application, as described above, bubbles may be formed within the reactor vessel (110) by injecting helium through the helium injection portion (115). The bubbles may absorb gaseous fission products, grow, and help them escape from the reactor system. In addition, the bubble can adsorb solid fission products existing at the interface of the bubble on a nano-micro scale and physically move them to a location where they do not affect the fission reaction, thermal-hydraulic behavior, or materials of the reactor system. Accordingly, according to the present application, the insoluble fission products can be easily collected, and the molten salt reactor (100) can be operated while maintaining the insoluble fission products below a predetermined level through the method described above.

[0103] Meanwhile, according to one embodiment, the circulation and reactivity of the reactor system can be controlled by using the helium injection amount provided from the helium injection unit (115) as a control variable. More specifically, the control of the circulation and reactivity of the reactor system can include maintaining the helium injection amount provided from the helium injection unit (115) to increase or decrease for a predetermined period of time. Accordingly, the molten salt reactor (100) can be operated stably.

[0104] More specifically, according to the present application, the injection of helium to remove the insoluble fission products within the reactor system of the molten salt reactor (100) can cause a heat flow environment with a two-phase natural circulation instead of a single-phase natural circulation. When helium is injected, the helium can rapidly rise upward due to the large density difference between the helium and the molten salt, which is the working fluid. As the helium rises, it can be heated by the surrounding molten salt, and its pressure can decrease depending on the molten salt head. Meanwhile, the rising helium can continue to rise while growing as it absorbs the gaseous insoluble fission products. However, the pressure of the rising helium can drop due to friction with the molten salt, which can result in transferring momentum to the molten salt. Accordingly, the circulation within the reactor system can increase. According to the present application, as described above, circulation can be formed by the density difference due to the temperature change of the molten salt and the buoyancy acting according to the density difference between the helium and the molten salt. Meanwhile, the buoyancy can be varied depending on the control of the helium injection amount. This may be because the nuclear fission reaction is greatly affected by the thermal hydraulic conditions within the reactor system. In other words, the thermal flow and reactor physical control can be adjusted by controlling the helium injection amount provided from the helium injection unit (115).

[0105] According to one embodiment, the off-gas system (116) may be provided at the upper portion of the reactor vessel (110), as illustrated in FIG. 4. Accordingly, helium inside the reactor vessel (110) may be discharged to the outside through the off-gas system (116). More specifically, referring to FIG. 5, the off-gas system (116) may include at least one of a long-delay holdup tank (116t), a compressor (116c), a surge tank (116s), a holdup tank (116h), or an inlet and outlet line (116p).

[0106] Referring to FIG. 6, the gas discharge system included in a conventional reactor may not include the long-delay hold-up tank (116t), compressor (116c), surge tank (116s), hold-up tank (116h), or inlet / outlet line (116p) described above, as illustrated in FIG. 6(a). As a result, the conventional reactor may have non-smooth gas discharge inside the reactor vessel.

[0107] However, according to an embodiment of the present application, the off-gas system (116) may include the long-delay hold-up tank (116t), the compressor (116c), the surge tank (116s), the hold-up tank (116h), or the input / output line (116p), as illustrated in FIGS. 5 and 6(b). Accordingly, the off-gas system (116) may discharge at least one of helium, gas, and volatile fission products injected through the helium injection unit (115).

[0108] According to one embodiment, the drum-type reactivity controller (117) may be provided inside the reactor system and outside the core (111), as illustrated in FIG. 7. Accordingly, the drum-type reactivity controller (117) may control the circulation and reactivity of the reactor system while not interfering with the flow in the core (111) and the riser (112). Meanwhile, the drum-type reactivity controller (117) may be operated in a direction to passively or actively suppress nuclear fission depending on a power cut. In other words, the circulation and reactivity of the reactor system may be controlled by using the rotation of the drum-type reactivity controller (117) as a control variable. More specifically, referring to FIGS. 7(a) and 7(b), the control of the circulation and reactivity of the reactor system may include rotating at least some of the absorbent pads (117p) of the drum-type reactivity controller (117) so that they face the core (111). Accordingly, the molten salt reactor (100) can be operated stably.

[0109] More specifically, during normal operation, the absorbent pad (117p) is rotated to be located far from the core (111), and in an accident situation, for example, when the reactor is stopped, the absorbent pad (117p) can be rotated to be located close to the core (111). Accordingly, the nuclear reaction in the core (111) can be controlled. That is, according to the embodiment of the present application, when the reactor is suddenly stopped, the core output can be rapidly reduced to less than 7% within 10 seconds, which corresponds to a commercial light water reactor, through a reduction in the output of the core (111).

[0110] Meanwhile, according to one embodiment, the reactor system may further include at least one unit among a neutron absorber (118), a control rod drive mechanism (CRDM) compartment (119), a secondary system pipe (120), or a separator (121), as illustrated in FIG. 2.

[0111] Referring back to FIG. 1, the molten salt reactor (100) may further include a containment vessel (150) surrounding the reactor vessel (110). In addition, referring to FIG. 2, the molten salt reactor (100) may include an inert salt (1) provided on the outside of the reactor vessel (110) and the inside of the containment vessel (150). According to an embodiment of the present application, the inert salt (1) may be in a liquid or solid state. The temperature inside the containment vessel (150) may decrease as it gets farther away from the center in the radial direction. That is, in other words, the temperature on the containment vessel (150) side of the molten salt reactor (100) may be lower than the temperature on the reactor vessel (110) side. Due to this, the inert salt (1) inside the containment vessel (150) can form an insulating solid layer (1s) on the inner wall of the containment vessel (150), as shown in Fig. 8(a). That is, referring to Fig. 8(a), the inert salt (1) can form a liquid layer (11) when adjacent to the reactor vessel (110), and can form a solid layer (1s) when adjacent to the containment vessel (150).

[0112] Meanwhile, according to an embodiment of the present application, the molten salt reactor (100) may further include a fluid line (126) surrounding the solid layer (1s) on the outside of the reactor vessel (110) and the inside of the containment vessel (150), as shown in FIG. 8(a).

[0113] In the fluid line (126), during normal operation of the molten salt reactor (100), helium injected into the reactor vessel (110) through the helium injection unit (115) described above can flow. Accordingly, the solid layer (1s) can be formed on the inner wall of the containment vessel (150). On the other hand, in contrast, when an accident occurs in the molten salt reactor (100), the helium supply can be cut off, and the flow of helium in the fluid line (126) can be blocked. As a result, the pressure inside the fluid line (126) can become lower than the pressure inside the reactor vessel (110). Accordingly, when an accident occurs, the molten salt (ms) inside the reactor vessel (110) can flow into the fluid line (126) through the helium injection unit (115). As the high-temperature molten salt (ms) flows in the fluid line (126), the solid layer (1s) surrounded by the fluid line (126) may be converted into a liquid phase and formed into a liquid layer (1l) as illustrated in FIG. 8(b). That is, in other words, the solid layer (1s) may be converted into the liquid layer (1l) when an accident occurs. The solid layer (1s) and the liquid layer (1l) have similar thermal conductivities, but the liquid layer (1l) may have superior heat transfer characteristics than the solid layer (1s) due to a convection phenomenon. That is, according to the present application, when an accident occurs as described above, the high-temperature molten salt (ms) can flow in the fluid line (126) surrounding the solid layer (1s), and thus, when the solid layer (1s) is converted into the liquid layer (11), the molten salt reactor (100) can be efficiently cooled through the liquid layer (11) having superior heat transfer characteristics than the solid layer (1s).This may mean that, according to the present application, a separate device for discharging the molten salt (ms) inside the reactor vessel (110) to the outside in the event of an accident is not necessary, and a separate device for cooling the molten salt reactor (100) in the event of an accident is also not necessary. In other words, the molten salt reactor (100) according to the embodiment of the present application can efficiently respond to an accident without requiring a separate device for preparing for an accident, and thus has the effect of enabling stable operation.

[0114] According to one embodiment, the inert salt (1) dilutes the nuclear fuel-coolant salt when discharged from the reactor vessel (110), and is selected from the group consisting of sodium chloride-magnesium chloride (NaCl-MgCl2), lithium chloride-potassium chloride (LiCl-KCl), lithium chloride-rubidium chloride (LiCl-RbCl), potassium chloride-magnesium chloride (KCl-MgCl2), sodium chloride-potassium chloride-magnesium chloride (NaCl-KCl-MgCl2), lithium chloride-potassium chloride-magnesium chloride (LiCl-KCl-MgCl2), potassium fluoride-zirconium fluoride (KF-ZrF4), sodium fluoride-sodium fluoroborate (NaF-NaBF4), potassium fluoride-potassium fluoroborate (KF-KBF4), rubidium fluoride-rubidium fluoroborate (RbF-RbBF4), or Lithium fluoride-sodium fluoride-potassium fluoride (LiF-NaF-KF) can be used in thermal energy storage devices.

[0115] According to one embodiment, the molten salt reactor (100) may further include a passage (127) having an inlet (122) for introducing outside air into the containment vessel (150) and an outlet (123) for discharging air inside the containment vessel (150) to the outside, as illustrated in FIG. 9. More specifically, as illustrated in FIG. 4, the passage (127) may be provided on the outside of the reactor vessel (110) and the inside of the containment vessel (150). The inlet (122) and the outlet (123) may be closed during normal operation of the molten salt reactor (100). Accordingly, heat inside the molten salt reactor (100) may be easily preserved during normal operation. On the other hand, in the event of an accident in the molten salt reactor (100), the inlet (122) and the outlet (123) can be opened passively or actively depending on a power cut. Meanwhile, the outlet (123) can be higher in height from the bottom surface of the containment vessel (150) than the inlet (122). Accordingly, according to the present application, in the event of an accident, external air can be easily introduced through the inlet (122), and internal air can be easily discharged through the outlet (123). As a result, the molten salt reactor (100) can be efficiently cooled.

[0116] According to one embodiment, the molten salt reactor (100) may include a structure having corrosion resistance and soundness at the molten salt contact surface inside the reactor vessel (110) and the containment vessel (150).

[0117] According to one embodiment, the interior of the reactor vessel (110) can be operated at a low pressure of less than 10 atm.

[0118] According to one embodiment, the nuclear fuel provided inside the reactor vessel (110) may be low enriched uranium (LEU) having a uranium-235 enrichment level of less than 20%. The enrichment level may be low enriched uranium of less than 5%, as in a typical commercial light water reactor, or high assay low enriched uranium (HALEU) of 5% to 20%.

[0119] In one embodiment, the working fluid of the reactor system includes the molten salt, and the molten salt may include sodium chloride-uranium trichloride (NaCl-UCl3) or potassium chloride-uranium trichloride (KCl-UCl3) or an actinide. In the present application, the actinide may include uranium (U) and plutonium (Pu) together as a material that can be utilized as fuel by extracting nuclear material from nuclear fuel after it has been used in a pyro-process or other method. However, this does not mean that its role or system characteristics are significantly different. In addition, in the embodiment of the present application, a gas that does not chemically react with the molten salt may be included in the upper space of the reactor vessel (110) where the molten salt does not exist. The chemically non-reactive gas may include at least one of helium (He), argon (Ar), krypton (Kr), xenon (Xe), carbon dioxide (CO2), or nitrogen (N2).

[0120]

[0121] FIG. 10 is a drawing for explaining a molten salt reactor system according to an embodiment of the present application.

[0122] Referring to FIG. 10, the molten salt reactor system (1000) may include the molten salt reactor (100) described above. In addition, referring to FIG. 10, the molten salt reactor system (1000) may be linked to a high-temperature water electrolysis-based hydrogen production facility and a power production facility.

[0123] According to an embodiment of the present application, the molten salt reactor system (1000) may further include a thermal energy storage system that receives heat from the reactor system and supplies thermal energy to the production system. The thermal energy storage system may include an intermediate heat exchanger low-temperature side that receives heat from the high-temperature side of the intermediate heat exchanger of the reactor system inside the reactor vessel, a thermal energy storage tank in which molten salt heated while passing through the intermediate heat exchanger low-temperature side moves and stores thermal energy, and a production heat exchanger that transmits the thermal energy to a site requiring a high-temperature heat source. The above thermal energy storage system comprises an inert salt that does not contain nuclear material, wherein the inert salt is sodium chloride-magnesium chloride (NaCl-MgCl2), lithium chloride-potassium chloride (LiCl-KCl), lithium chloride-rubidium chloride (LiCl-RbCl), potassium chloride-magnesium chloride (KCl-MgCl2), sodium chloride-potassium chloride-magnesium chloride (NaCl-KCl-MgCl2), lithium chloride-potassium chloride-magnesium chloride (LiCl-KCl-MgCl2), potassium fluoride-zirconium fluoride (KF-ZrF4), sodium fluoride-sodium fluoroborate (NaF-NaBF4), potassium fluoride-potassium fluoroborate (KF-KBF4), rubidium fluoride-rubidium fluoroborate (RbF-RbBF4), or Lithium fluoride-sodium fluoride-potassium fluoride (LiF-NaF-KF) can be used in thermal energy storage devices.

[0124] According to one embodiment, the low-temperature side of the intermediate heat exchanger receives heat from the high-temperature side of the intermediate heat exchanger (113) of the reactor system inside the reactor vessel (110), and the molten salt heated while passing through the low-temperature side of the intermediate heat exchanger moves, so that the thermal energy is stored in the thermal energy storage tank, and the flow within the thermal energy storage system is controlled according to energy demand, and the thermal energy can be supplied from the thermal energy storage system to the production system through the production heat exchanger.

[0125] According to one embodiment, the production heat exchanger includes transferring heat to a utilization site including power generation, district heating, seawater desalination, hydrogen production, or process heat source requiring a high temperature heat source, wherein the production facilities of the utilization site may be installed one or more times on site.

[0126]

[0127] FIG. 11 is a drawing for explaining a control method of a molten salt reactor system according to an embodiment of the present application.

[0128] Referring to FIG. 11, when the reactor system (1000) becomes unstable due to an unexpected accident, that is, a change that is difficult to predict, during the operation of the molten salt reactor (100), a change in the temperature of the neutron flux can be measured. For example, when the temperature is measured in an increasing direction, the unexpected accident may be a situation in which the temperature of the core (111) increases. When the temperature of the core (111) increases, the flow rate within the reactor vessel (110) may also decrease. As a result, the nuclear fission reaction may be reduced. However, according to an embodiment of the present application, the nuclear fission reduction as described above can be quickly recovered by increasing the flow rate within the reactor vessel (110). More specifically, according to an embodiment of the present application, as illustrated in FIG. 11, if the reaction is unacceptable, that is, exceeding the allowable range, a first response can be performed, and if the reaction is acceptable, that is, below the allowable range, a second response can be performed to determine whether the output change is acceptable while adjusting the temperature to a normal level.

[0129] The above first response may include controlling the circulation and reactivity of the reactor system by using the rotation of the drum-type reactivity controller (117) described above as a control variable. More specifically, the control of the circulation and reactivity of the reactor system may include rotating at least some of the absorbent pads (117p) of the drum-type reactivity controller (117) so that they face the core (111), as described above with reference to FIG. 7. Accordingly, the molten salt reactor (100) may be operated stably.

[0130] The second response may include controlling the circulation and reactivity of the reactor system by using the helium injection amount provided from the helium injection unit (115) described above as a control variable. More specifically, controlling the circulation and reactivity of the reactor system may include maintaining the helium injection amount provided from the helium injection unit (115) to increase or decrease for a predetermined period of time. Accordingly, the molten salt reactor (100) may be operated stably.

[0131] That is, according to the present application, when the temperature of the primary system working fluid increases, the density of the nuclear fuel decreases, so the reactivity progresses in the direction of decreasing, and as the reactivity decreases, the output of the core (111) may also decrease. Accordingly, the temperature of the molten salt reactor (100) may decrease. On the other hand, when the temperature of the working fluid decreases, the density of the nuclear fuel increases, so the reactivity progresses in the direction of increasing, and as the reactivity increases, the output of the core (111) may also increase. Accordingly, the temperature of the molten salt reactor (100) may increase again. This is a unique characteristic of the molten salt reactor that can help stable operation, but according to the present application, in a reactor system that does not include a pump, an unstable state may persist for a long time, or an abnormal state may occur before the flow and reactivity are stabilized according to the characteristic, and therefore, stable operation that shortens the duration of the unstable state may be required. Accordingly, in the present application, the amount of helium injected in the core (111) or the riser (112) can be adjusted, and the rotation of the drum-type reactivity controller (117) can be controlled to control the flow and reactivity for stable operation. In addition, according to the present application, by providing a thermal energy storage system as illustrated in FIG. 10, it is possible to compensate for some of the unstable, for example, low or high, output changes for a very short period of time during the control process. That is, as described above with reference to FIG. 11, when an unstable state occurs due to a change that is difficult to predict during stable operation, the change can be confirmed through measurement in the core (111). In addition, the unstable state can also be confirmed by measuring the steam generator inlet and outlet temperatures and neutron flux. According to the present application, as described above, the amount of helium injected can be increased and / or decreased as the temperature of the core (111) increases and / or decreases, and accordingly, the temperature and flow rate of the working fluid can be controlled to an operation-appropriate level.Accordingly, according to the present application, it is possible to respond faster than changes due to inherent characteristics according to temperature changes. Although the change in output for a short period of time can be handled by the heat storage system (secondary system), if the time required to reach stabilization is insufficient, the molten salt reactor (100) can be stabilized by partially rotating the drum-type reactivity controller (117) or increasing the amount of helium injected through the helium injection unit (115) or extending the time. According to the present application, the above-described process can be repeatedly performed, and the molten salt reactor (100) can be operated while maintaining a stable state.

[0132]

[0133] FIG. 12 is a drawing for explaining a molten salt reactor structure according to an embodiment of the present application.

[0134] The molten salt reactor structure (2000) may include the molten salt reactor (100). According to one embodiment, in the molten salt reactor structure (2000), the surrounding environment of the molten salt reactor (100) may be at a pressure below atmospheric pressure and may include an atmospheric atmosphere, but the pressure below atmospheric pressure may include a non-pressurized atmosphere. The molten salt reactor structure (2000) may be, for example, a building including the molten salt reactor (100).

[0135] According to one embodiment, the molten salt reactor structure (2000) may include one or more molten salt reactors (100). In other words, the molten salt reactors (100) may be installed one or more times within the molten salt reactor structure (2000). In addition, the molten salt reactor structure (2000) may be included in a site environment including a high-temperature water electrolysis-based hydrogen production facility and a power production facility. More specifically, referring to FIG. 12, the molten salt reactor structure (2000) may be connected to at least one of a high-temperature steam electrolysis (HTSE) plant, cooling towers, a switchyard, a turbine building, or an auxiliary building. Accordingly, the present invention has the effect of drastically reducing the site size in comparison to productivity compared to existing nuclear power facilities.

[0136]

[0137] Below, an experimental example of the present application is described.

[0138]

[0139] Figure 13 is a graph evaluating the possibility of long-period, long-life operation of a molten salt reactor according to an experimental example of the present application through computer analysis.

[0140] Referring to Figure 13, the results of evaluating the residual reactivity of a molten salt reactor according to the experimental example of the present application through Monte-Carlo simulation can be observed. Figure 13 demonstrates that the molten salt reactor according to the experimental example of the present application can achieve long-term, long-life operation of more than 20 years.

[0141]

[0142] Figure 14 is a graph evaluating the safety in the event of an accident in a molten salt reactor according to an experimental example of the present application.

[0143] Referring to Fig. 14, the results of a computerized evaluation of the cooling performance of a molten salt reactor according to an experimental example of the present application in the event of an accident can be observed. As shown in Fig. 14, the molten salt reactor according to the experimental example of the present application maintains a temperature below 800°C even without any additional work performed due to the opening of the passively operating external air system in the event of an accident. Therefore, it can be proven that the molten salt reactor according to the experimental example of the present application can ensure long-term safety through air cooling alone, without the use of external power or AC power.

[0144]

[0145] While the present invention has been described in detail using preferred embodiments, the scope of the present invention is not limited to the specific embodiments described above, and should be interpreted in accordance with the appended claims. Furthermore, those skilled in the art will appreciate that numerous modifications and variations are possible without departing from the scope of the present invention.

Claims

1. Reactor vessel; and Including a containment vessel surrounding the reactor vessel, Including an inert salt provided on the outside of the reactor vessel and the inside of the containment vessel, The above inactive salt is a molten salt reactor, including a liquid or solid one.

2. In paragraph 1, Inside the reactor vessel, a reactor system is included, The above reactor system includes at least one unit among a reactor core, a riser, an intermediate heat exchanger high-temperature side, or a downcomer. The heat production mechanism of the above core is a molten salt reactor, including nuclear fission by fast neutron spectrum.

3. In paragraph 1, The temperature inside the above containment vessel decreases as it moves away from the center in the radial direction. The inactive salt inside the containment vessel forms a solid insulating layer on the inner wall of the containment vessel, but is converted to a liquid state when an accident occurs. The above inert salt is used to dilute the nuclear fuel-coolant salt when discharged from the reactor vessel, and is selected from the group consisting of sodium chloride-magnesium chloride (NaCl-MgCl2), lithium chloride-potassium chloride (LiCl-KCl), lithium chloride-rubidium chloride (LiCl-RbCl), potassium chloride-magnesium chloride (KCl-MgCl2), sodium chloride-potassium chloride-magnesium chloride (NaCl-KCl-MgCl2), lithium chloride-potassium chloride-magnesium chloride (LiCl-KCl-MgCl2), potassium fluoride-zirconium fluoride (KF-ZrF4), sodium fluoride-sodium fluoroborate (NaF-NaBF4), potassium fluoride-potassium fluoroborate (KF-KBF4), rubidium fluoride-rubidium fluoroborate (RbF-RbBF4), or A molten salt reactor, including one used in a lithium fluoride-sodium fluoride-potassium fluoride (LiF-NaF-KF) thermal energy storage device.

4. In paragraph 2, A helium injection unit provided at the lower part or the upper part of the reactor vessel and injecting helium into the reactor vessel; and An off-gas system is provided on the upper part of the reactor vessel and discharges helium inside the reactor vessel, A molten salt reactor, wherein the off-gas system comprises at least one of helium, gas, and volatile fission products injected through the helium injection unit.

5. In paragraph 2, A drum-type reactivity controller is included inside the reactor system and outside the core, A molten salt reactor, wherein the drum-type reactivity controller controls the circulation and reactivity of the reactor system while not interfering with the flow in the core and the riser, and operates in a direction that passively or actively suppresses nuclear fission according to a power cut.

6. In paragraph 4 or 5, A molten salt reactor, comprising a helium injection amount provided from the helium injection unit or the rotation of the drum-type reactivity controller as a control variable, wherein the circulation and reactivity of the reactor system are controlled.

7. In paragraph 6, Control of the circulation and reactivity of the above reactor system is A first control for rotating at least some of the absorber pads of the drum-type reaction controller so that they face the core; or A molten salt reactor comprising at least one of a second control for maintaining the amount of helium injected from the helium injection unit to increase or decrease for a predetermined period of time.

8. In paragraph 2, The upper or middle heat exchanger of the reactor vessel is provided in an assembled form for separation, mounting, installation, inspection, or replacement. A molten salt reactor, wherein the intermediate heat exchanger comprises a shell and helical-coil tube heat exchanger or a printed circuit heat exchanger.

9. In paragraph 1, an inlet for introducing outside air into the containment vessel; and Including an exhaust port for discharging air inside the containment vessel to the outside, The above inlet and outlet are closed during normal operation and open passively or actively according to power cut, A molten salt reactor, wherein the outlet is higher than the inlet from the bottom surface of the containment vessel.

10. In paragraph 1, A structure having corrosion resistance and soundness is included in the molten salt contact surface inside the reactor vessel and the containment vessel, The inside of the reactor vessel is operated at a low pressure of less than 10 atmospheres, Including nuclear fuel provided inside the reactor vessel, A molten salt reactor, wherein the nuclear fuel comprises low-enriched uranium (LEU) having an enrichment of uranium-235 of less than 20%.

11. In paragraph 2, The working fluid of the above reactor system includes a molten salt, The above molten salt comprises sodium chloride-uranium trichloride (NaCl-UCl3) or potassium chloride-uranium trichloride (KCl-UCl3) or actinide, In the upper space of the reactor vessel where the molten salt does not exist, a gas that does not chemically react with the molten salt is included. A molten salt reactor wherein the chemically non-reactive gas comprises at least one of helium (He), argon (Ar), krypton (Kr), xenon (Xe), carbon dioxide (CO2), or nitrogen (N2).

12. In paragraph 2, A molten salt reactor, wherein the core is non-chemically processed (online-reprocessing) during operation, non-injection of additional nuclear fuel, and long-life operation of more than 20 years.

13. In a molten salt reactor system including a molten salt reactor according to paragraph 1, Further including a thermal energy storage system that receives heat from the reactor system and supplies thermal energy to the production system, The above thermal energy storage system, An intermediate heat exchanger low-temperature side that receives heat from the high-temperature side of the intermediate heat exchanger of the reactor system inside the reactor vessel; A thermal energy storage tank in which heated molten salt moves through the low-temperature side of the intermediate heat exchanger and heat energy is stored; and A molten salt reactor system comprising a production heat exchanger for transferring the heat energy to an application requiring a high temperature heat source.

14. In paragraph 13, The above thermal energy storage system comprises an inert salt that does not contain nuclear material, The molten salt reactor system includes a salt used in a thermal energy storage device, wherein the inert salt is sodium chloride-magnesium chloride (NaCl-MgCl2), lithium chloride-potassium chloride (LiCl-KCl), lithium chloride-rubidium chloride (LiCl-RbCl), potassium chloride-magnesium chloride (KCl-MgCl2), sodium chloride-potassium chloride-magnesium chloride (NaCl-KCl-MgCl2), lithium chloride-potassium chloride-magnesium chloride (LiCl-KCl-MgCl2), potassium fluoride-zirconium fluoride (KF-ZrF4), sodium fluoride-sodium fluoroborate (NaF-NaBF4), potassium fluoride-potassium fluoroborate (KF-KBF4), rubidium fluoride-rubidium fluoroborate (RbF-RbBF4), or lithium fluoride-sodium fluoride-potassium fluoride (LiF-NaF-KF).

15. In paragraph 13, The flow within the thermal energy storage system is regulated according to energy demand. A molten salt reactor system, comprising supplying the thermal energy from the thermal energy storage system to the production system through the production heat exchanger.

16. In paragraph 13, The above-mentioned application is a molten salt reactor system including at least one of power generation, district heating, seawater desalination, hydrogen production, or process heat source that requires a high temperature heat source.

17. In a molten salt reactor structure including a molten salt reactor according to paragraph 1, The surrounding environment of the above molten salt reactor is below atmospheric pressure and includes an atmospheric atmosphere, A molten salt reactor structure, wherein the sub-atmospheric pressure includes non-pressurized.

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