Molten salt nuclear reactor core

Abstract

A nuclear reactor core (1) for a molten salt nuclear reactor (100). The nuclear reactor core (1) has a tubular cylindrical central moderator vessel (10) used as a passage for a liquid moderator (11), a cylindrical fuel salt jacket surrounding the central moderator vessel (10), and a cylindrical neutron reflector jacket surrounding the cylindrical fuel salt jacket, wherein the cylindrical central moderator and neutron reflector vessel (10) has a maximum internal cross-sectional area between a liquid moderator and neutron reflector inlet (12) of the central moderator and neutron reflector vessel (10) and a liquid moderator and neutron reflector outlet (13) of the moderator and neutron reflector vessel (10).

Description

Technical Field

[0001] The present disclosure relates to a molten salt nuclear reactor core and a method of operating such a nuclear reactor core, and in particular to the construction and design of a molten salt nuclear reactor core and a method of operating such a nuclear reactor core. Background Art

[0002] A molten salt reactor (MSR) is a nuclear reactor in which the nuclear reactor coolant and / or nuclear fuel is a molten salt, which is usually a fluoride salt or chloride salt with a melting point of about 500°C, and the operating temperature of the nuclear reactor is about 600°C to 700°C, and the boiling point is about 1000°C above the melting point. One of the many advantages of this reactor is that molten salt can be used as a heat transfer medium at very high temperatures while still operating at or near atmospheric pressure. Heat can be extracted from this reactor by pumping molten salt in a loop between the nuclear reactor core and the heat exchanger, where the reactor power is directly proportional to the flow rate and the temperature drop across the heat exchanger. Due to the corrosive nature of molten fluoride and chloride salts, their operation requires an inert containment atmosphere, and in addition, the molten salt or molten salt vapor is not allowed to escape into the environment, which places strict requirements on the complete sealing of molten salt reactor components. This poses a severe technical challenge, because the temperature and corrosiveness of the molten salt, coupled with the high radiation levels, only a very small number of suitable materials can be used. Therefore, the materials that can be used to build the core must be carefully selected and combined to obtain a solution that provides a reliable and durable nuclear reactor core.

[0003] Molten salt reactors were built and operated at Oak Ridge National Laboratory (ORNL) in the 1950s and 1960s, with a research program that continued into the 1970s, and there were other smaller projects around the world.

[0004] A nuclear reactor core has a special geometry designed to allow a nuclear chain reaction to take place, which is achieved in two ways:

[0005] 1. A sufficient amount of fuel to form a critical assembly; or

[0006] 2. Combine enough moderator and fuel to make a critical assembly.

[0007] These two types of reactors are called fast reactors and thermal reactors, respectively, because of the spectrum of neutrons each produces.

[0008] In order to meet future global energy needs in a sustainable manner, molten salt breeder reactors that are compact and can be manufactured on a large scale are needed. This poses a huge challenge, as the smaller the reactor, the more difficult it is to achieve breeding, because the probability of neutrons leaving the reactor (i.e., neutron leakage) increases with the surface area to volume ratio of a small reactor.

[0009] Fast reactors generally require larger stocks of fissile material to achieve criticality than thermal reactors, and are therefore not suitable for rapid scale-up to meet future energy needs due to the limited supply of fissile material. Therefore, there is a need for a thermal molten salt breeder reactor that is compact and can be manufactured on a large scale.

[0010] One of the challenges of thermal molten salt breeder reactors is the need for a moderator that is both effective at slowing down neutrons and allowing breeding to occur, which means that only carbon, beryllium, or deuterium based moderators can be used. The only practical moderators that will allow breeding in a thermal spectrum molten salt reactor are: solid carbon, solid beryllium, molten lithium-enriched deuterium oxide salts (7LiOD), or liquid heavy water (D20). Of these, carbon is the only one that can withstand direct contact with the fuel salt, while the others require a structural material to separate it from the fuel salt. All of these moderators have their pros and cons, and have been proposed and studied in the past for use as moderators in molten salt reactors.

[0011] Another challenge is the selection of materials for containers containing fuel salt or moderator material if the moderator is separated from the fuel salt. These materials need to resist degradation under extremely high temperatures and intense radiation exposure, and must also have appropriate neutron absorption properties and be able to resist the corrosive effects of the molten salt on the container containing the molten salt. Various materials have been proposed and studied in the past for use in the construction of molten salt reactor components. However, each of these materials has practical limitations in the shapes that can be manufactured commercially.

[0012] The only known materials with low neutron absorption that are compatible with molten salts are carbon-based materials and silicon carbide-based materials. Among them, the most promising are ceramic composites of silicon carbide and carbon, such as carbon fiber-carbon matrix C / C composites, silicon carbide fiber-silicon carbide matrix (SiC / SiC) composites, and silicon carbide fiber-carbon matrix (SiC / C) composites. The manufacture of complex-shaped composites is more challenging than that of metal materials, because these complex-shaped composites cannot be bent or welded into their final shape, but must be molded and processed through multiple steps such as furnace firing.

[0013] CN112259263A discloses a nuclear reactor core having a structure of a straight cylindrical container which is relatively easy to construct with suitable materials, but which cannot provide an effective reactor design for minimizing neutron leakage. Summary of the invention

[0014] The object is to provide a nuclear reactor core for a nuclear reactor that overcomes or at least reduces the above mentioned problems.

[0015] These and other objects are achieved by the features of the independent claims. Further embodiments can be seen in the dependent claims, the description and the drawings.

[0016] According to a first aspect, there is provided a nuclear reactor core for a molten salt nuclear reactor, the nuclear reactor core comprising:

[0017] - a substantially cylindrical tubular central moderator and neutron reflector container, said central moderator and neutron reflector container serving as a passage for liquid moderator and neutron reflector extending axially from a liquid moderator and neutron reflector inlet to a liquid moderator and neutron reflector outlet,

[0018] - a plurality of tubular fuel salt containers, each tubular fuel salt container extending axially from a fuel salt inlet to a fuel salt outlet for passage of molten fuel salt, the plurality of tubular fuel salt containers being assembled to form a generally cylindrical fuel salt jacket surrounding the central moderator and neutron reflector container,

[0019] - a plurality of tubular moderator and neutron reflector containers, each tubular moderator and neutron reflector container extending axially from a liquid moderator and neutron reflector inlet to a liquid moderator and neutron reflector outlet for passage of liquid moderator and neutron reflector, the plurality of tubular moderator and neutron reflector containers being assembled to form a generally cylindrical moderator and neutron reflector jacket surrounding the generally cylindrical fuel-salt jacket, and

[0020] - a generally cylindrical central moderator and neutron reflector vessel having a maximum internal cross-sectional area between said liquid moderator and neutron reflector inlet of the central moderator and neutron reflector vessel and said liquid moderator and neutron reflector outlet of said moderator and neutron reflector vessel.

[0021] By constructing a nuclear reactor core with a fuel salt jacket formed by a plurality of tubular containers, which form the fuel salt jacket after assembly, and by constructing a nuclear reactor core with a neutron reflector jacket formed by a plurality of tubular containers, which form the neutron reflector jacket after assembly, a nuclear reactor core with a concentric cylindrical design can be constructed, which cylindrical parts can have different radii to allow a larger volume portion in the corresponding concentric space between each cylindrical part, in which the moderator and reflector liquid and molten fuel salt can be accommodated, thereby achieving a critical assembly and reducing neutron leakage, that is, an efficient reactor geometry, while being manufactured with materials suitable for use in molten salt nuclear reactors. These components are made of materials that usually need to be manufactured in molds, which in turn imposes a series of restrictions on the design of these components. The core construction according to the present invention allows these components to be designed so that they can be manufactured from suitable materials, such as ceramic composites and metal alloys, which are preferably zirconium alloys. The construction of a nuclear reactor core according to the first aspect allows for an optimized core design with an efficient reactor geometry, requiring only a small amount of fuel salt to form a critical reactor assembly while also allowing for practical assembly and also allowing for sufficient fuel salt circulation rates to extract the generated heat, wherein a generally cylindrical central moderator and neutron reflector vessel has a maximum internal cross-sectional area at a location midway between a liquid moderator inlet and a liquid moderator and neutron reflector outlet.

[0022] In a possible implementation of the first aspect, the ceramic composite material is a ceramic matrix composite material.

[0023] In a possible implementation form of the first aspect, the ceramic composite material is a ceramic composite material of silicon carbide and carbon, preferably a carbon fiber-carbon matrix (C / C) composite material, a silicon carbide fiber-silicon carbide matrix (SiC / SiC) composite material and / or a silicon carbide fiber-carbon matrix (SiC / C) composite material.

[0024] In a possible implementation form of the first aspect, at least in a portion of the axial range of the central moderator and neutron reflector container, the internal cross-sectional area of ​​the central moderator and neutron reflector container gradually increases toward an intermediate position between the liquid moderator and neutron reflector inlet and the liquid moderator and neutron reflector outlet. Preferably, at least in a portion of the axial range of the central moderator and neutron reflector container, the internal cross-sectional area changes continuously between the moderator and neutron reflector inlet and the moderator and neutron reflector outlet.

[0025] In a possible implementation form of the first aspect, the substantially cylindrical central moderator and neutron reflector container and / or the liquid moderator and neutron reflector container have a metal alloy wall or a ceramic composite wall, preferably the metal alloy is an iron alloy, preferably the metal alloy is stainless steel, more preferably the metal alloy is a zirconium alloy, and wherein, preferably the fuel salt container has a wall made of the following materials: a ceramic composite, a metal alloy, an iron alloy or a nickel alloy, preferably the iron alloy is stainless steel, preferably the nickel alloy is Inconel or Hastelloy

[0026] In a possible implementation form of the first aspect, each fuel-salt container in the fuel-salt jacket is substantially identical to the other fuel-salt containers in the fuel-salt jacket.

[0027] In a possible implementation form of the first aspect, each moderator and neutron reflector container in the moderator and neutron reflector jacket is substantially identical to the other moderator and neutron reflector containers in the moderator and neutron reflector jacket.

[0028] In a possible implementation form of the first aspect, a substantially cylindrical first insulating jacket is provided between the central moderator container and the fuel salt jacket, preferably, the first insulating jacket is formed by one or more first insulating members, preferably, the first insulating member is shaped similar to a sector of the substantially cylindrical first insulating jacket, or the first insulating member is shaped as a strip wound spirally around the central moderator container, and preferably, the first insulating member is made of graphite felt or graphite felt impregnated with insulating aerogel. The insulating member allows to significantly reduce the heat loss of the moderator and the neutron reflecting liquid, and allows the moderator and the neutron reflecting liquid to always operate at a much lower temperature than the fuel salt, which is a significant advantage if a hydroxide or deuterium oxide moderator is used, because the corrosion effect is reduced at lower temperatures.

[0029] In a possible implementation form of the first aspect, a second insulating jacket having a substantially cylindrical shape is provided between the fuel salt jacket and the moderator and neutron reflector jacket, the second insulating jacket is preferably composed of one or more second insulating members, the second insulating members are preferably shaped similar to sectors of the second insulating jacket having a substantially cylindrical shape, or the second insulating members are shaped as strips spirally wound around the fuel salt jacket, and the second insulating members are preferably made of graphite felt or graphite felt impregnated with insulating aerogel.

[0030] In a possible implementation form of the first aspect, the nuclear reactor core includes a plurality of tubular cladding salt containers, each of which extends axially from an inlet to an outlet to serve as a passage for molten cladding salt, and the plurality of tubular cladding salt containers are assembled to form a generally cylindrical cladding salt jacket surrounding a moderator and neutron reflector jacket.

[0031] In a possible implementation form of the first aspect, a substantially cylindrical third insulation jacket is provided between the neutron reflector container and the cladding salt jacket, the third insulation jacket is preferably composed of one or more third insulation members, the third insulation members are preferably shaped similar to sectors of the substantially cylindrical third insulation jacket, or are shaped as strips spirally wound around the moderator and the neutron reflector jacket, and the third insulation members are preferably made of graphite felt or graphite felt impregnated with insulating aerogel.

[0032] In a possible implementation form of the first aspect, the graphite felt or the graphite felt impregnated with insulating aerogel of the first substantially cylindrical insulating jacket, the second substantially cylindrical insulating jacket or the third substantially cylindrical insulating jacket is coated on a sheet metal, preferably, the sheet metal has a thickness of about 0.01 mm to 0.1 mm to eliminate or at least reduce the risk of salt wicking.

[0033] In a possible implementation form of the first aspect, the central moderator and neutron reflector container, the fuel salt container, the moderator and neutron reflector container, and / or the blanket salt container are each assembled from two parts, which are separated by a symmetry plane M extending radially from a middle position.

[0034] In a possible implementation form of the first aspect, the central moderator and neutron reflector container has a variable inner radius R11 and outer radius R12, which are preferably largest at or near a middle position and gradually decrease from the middle position.

[0035] In a possible implementation form of the first aspect, the fuel-salt jacket is shaped as an annular hollow cylindrical member having a variable inner radius R21 and an outer radius R22, and wherein the fuel-salt container is preferably shaped as a substantially annular cylindrical sector having a variable inner radius R21 and an outer radius R22, or having effective radii R21' and R22', respectively, and having a given sector angle A2, wherein the inner radius R21 and the outer radius R22, or the effective radii R21' and R22', are preferably the largest at or near a middle position, and gradually decrease from the middle position.

[0036] In a possible implementation form of the first aspect, the moderator and neutron reflector jacket is shaped like an annular hollow cylindrical member with a variable inner radius R31 and an outer radius R32, and wherein the moderator neutron reflector container is preferably shaped like a substantially annular cylindrical sector with a variable inner radius R31 and an outer radius R32, or with effective radii R31' and R32', respectively, and with a given sector angle A3, and the inner radius R31 and the outer radius R32, or the effective radii R31' and R32', are preferably the largest at or near the middle position, and gradually decrease from the middle position.

[0037] In a possible implementation form of the first aspect, the cladding salt jacket is formed as an annular hollow cylindrical member having a variable inner radius R41 and an outer radius R42 or effective radii R41' and R42', and wherein the cladding salt container is formed as a sector-shaped member similar to a substantially annular cylinder having a variable inner radius R41 and an outer radius R42 or effective radii R41' and R42', respectively, and having a given sector angle A4, the inner radius R41 and the outer radius R42 or the effective radii R41' and R42' are preferably the largest at or near the middle position, and gradually decrease from the middle position.

[0038] In a possible implementation form of the first aspect, the fuel-salt jacket, the neutron reflector jacket and / or the cladding jacket are jackets that may be continuous in the circumferential direction. Preferably, the fuel-salt jacket, the neutron reflector jacket and / or the cladding jacket are formed by matching side portions of tubular containers forming these jackets contacting each other along most of their axial extent.

[0039] In a possible implementation form of the first aspect, the central moderator container is segmented and formed by a plurality of tubular moderator containers, each of which extends axially from a moderator inlet to a moderator outlet to serve as a passage for the moderator, and the plurality of tubular moderator containers are assembled to form the central moderator container.

[0040] In a possible implementation form of the first aspect, the central moderator container has a circumferential outer wall and a circumferential inner wall, and the circumferential inner wall preferably forms a cavity for receiving the control rods.

[0041] In a possible implementation form of the first aspect, the liquid moderator is heavy water.

[0042] In a possible implementation form of the first aspect, the fuel salt includes a fissile component, preferably an enriched 7 lithium fluoride, thorium tetrafluoride, uranium tetrafluoride, uranium trifluoride and / or plutonium trifluoride (7LiF)-(ThF4)-(UF4)-(UF3)-(PuF3) salt.

[0043] In a possible implementation form of the first aspect, the cladding salt is a molten salt comprising a convertible component, preferably comprising an enriched 7 lithium fluoride and / or thorium tetrafluoride (7LiF)-(ThF4) salt.

[0044] In a possible implementation form of the first aspect, the nuclear reactor core is provided with a movable neutron absorption control element between the containers of the jacket, preferably between the containers constituting the fuel-salt jacket and / or between the containers forming the jacket surrounding the fuel jacket or surrounded by the fuel jacket. The neutron absorption control element is similar to the control rod, but the neutron absorption control element is not rod-shaped, but is shaped like a plate or a wedge to match with the adjacent container in the relevant jacket, and the neutron absorption control element is arranged so that the neutron absorption control element can be inserted into the nuclear reactor core and retracted from the nuclear reactor core for controlling the nuclear reactivity of the nuclear reactor core.

[0045] In a possible implementation form of the first aspect, the second fuel-salt jacket surrounds the moderator and neutron reflector jacket, and the second moderator and neutron reflector jacket surrounds the second fuel-salt jacket. In this implementation form, if a cladding jacket is present, the cladding jacket surrounds the second neutron reflector jacket. In this implementation form, the second fuel-salt jacket is formed by a plurality of tubular fuel-salt containers, each of which extends axially from a fuel-salt inlet to a fuel-salt outlet to serve as a passage for molten fuel-salt, and a plurality of tubular fuel-salt containers are assembled together to form a cylindrical second fuel-salt jacket surrounding the moderator and neutron reflector jacket. The second neutron reflector jacket is formed by a plurality of tubular moderator and neutron reflector containers. Each tubular moderator and neutron reflector container extends axially from a liquid moderator and neutron reflector inlet to a liquid moderator and neutron reflector outlet to serve as a passage for liquid moderator and neutron reflector.

[0046] Another object of the present invention is to provide a method of operating a nuclear reactor core which overcomes or at least reduces the above-mentioned problems.

[0047] According to a second aspect, there is provided a method of operating a molten salt nuclear reactor core, the nuclear reactor core comprising:

[0048] - a cylindrical tubular central moderator and neutron reflector container, which serves as a passage for liquid moderator and neutron reflector extending axially from a liquid moderator and neutron reflector inlet to a liquid moderator and neutron reflector outlet,

[0049] a cylindrical fuel-salt jacket surrounding the central moderator vessel, the fuel-salt jacket extending axially from a fuel-salt inlet to a fuel-salt outlet for passage of molten fuel-salt, and

[0050] a cylindrical moderator and neutron reflector jacket, the cylindrical moderator and neutron reflector jacket surrounding the fuel-salt jacket, the moderator and neutron reflector jacket axially extending from the cylindrical liquid moderator and neutron reflector inlet to the moderator and neutron reflector outlet to serve as a passage for the liquid moderator and neutron reflector,

[0051] The method includes:

[0052] - controlling the temperature of the fuel salt in the fuel salt jacket to be maintained at a temperature between about 600° C. and 700° C.,

[0053] - controlling the temperature of the moderator and neutron reflector liquid in the central moderator and neutron reflector container to be maintained at a temperature between about 10°C and 90°C, and

[0054] - Preferably, the temperature of the moderator and neutron reflector liquid in the moderator and neutron reflector jacket is controlled to be maintained at a temperature of approximately between 10°C and 90°C.

[0055] By controlling the temperature of the moderator to between about 10°C and 90°C, the moderator and neutron reflector, usually heavy water, do not need to be pressurized to prevent them from boiling. In this way, the container containing the moderator and neutron reflector does not need to act as a pressure vessel and can therefore be built lighter and less sturdy. This is a great advantage, because suitable materials with the required properties are difficult to use in structures that need to withstand pressure (pressure vessels). Therefore, the construction of the nuclear core is greatly facilitated.

[0056] In a possible implementation form of the second aspect, the method includes:

[0057] - regulating the level or mass of the liquid moderator and neutron reflector in the central moderator and neutron reflector container, and / or

[0058] - regulating the level or mass of the liquid moderator and neutron reflector in the moderator and neutron reflector jacket, and / or

[0059] - regulating the level or quality of molten cladding salt in the cladding salt jacket, and / or

[0060] - regulating the temperature of the fuel salt in the fuel jacket, and / or

[0061] - regulating the temperature of the liquid moderator and neutron reflector in the central moderator and neutron reflector container, and / or

[0062] - regulating the temperature of the liquid moderator and neutron reflector in the moderator and neutron reflector jacket, and / or

[0063] - Adjust the chemical composition of the liquid moderator and neutron reflector, and / or

[0064] - Adjust the chemical composition of the fuel salt, and / or

[0065] - regulating the flow rates of liquid moderator and neutron reflector in the central moderator and neutron reflector container, and / or

[0066] - adjusting the position of a control rod at least partially inserted into the cavity of the central moderator and neutron reflector container, and / or

[0067] - adjusting the position of a control rod at least partially inserted between the fuel-salt containers, and / or

[0068] - adjusting the position of a control rod at least partially inserted between the moderator and the neutron absorber vessel.

[0069] In a possible implementation form of the second aspect, the control rods are made of a neutron absorbing material such as boron or hafnium.

[0070] In a possible implementation form of the second aspect, the liquid moderator is heavy water.

[0071] In a possible implementation form of the second aspect, the fuel salt includes a fissile component, preferably an enriched 7 lithium fluoride, thorium tetrafluoride, uranium tetrafluoride, uranium trifluoride and / or plutonium trifluoride (7LiF)-(ThF4)-(UF4)-(UF3)-(PuF3) salt.

[0072] In a possible implementation form of the second aspect, the cladding salt is a molten salt comprising a convertible component, preferably comprising an enriched 7 lithium fluoride and / or thorium tetrafluoride (7LiF)-(ThF4) salt.

[0073] According to a third aspect, there is provided a molten salt nuclear reactor comprising a controller configured to perform the method according to the second aspect or according to any possible implementation form of the second aspect.

[0074] Another object of the present invention is to provide a nuclear reactor core which overcomes or at least reduces the above-mentioned problems.

[0075] According to a fourth aspect, a nuclear reactor core of a molten salt nuclear reactor is provided, the nuclear reactor core comprising:

[0076] a cylindrical tubular central moderator and neutron reflector container, said central moderator and neutron reflector container serving as a passage for liquid moderator and neutron reflector extending axially from a liquid moderator and neutron reflector inlet to a liquid moderator and neutron reflector outlet, said central moderator and neutron reflector container having a metal alloy wall, preferably a zirconium alloy, or a ceramic composite wall,

[0077] a cylindrical fuel-salt jacket surrounding the central moderator vessel, the fuel-salt jacket extending axially from the fuel-salt inlet to the fuel-salt outlet to serve as a passage for molten fuel-salt, the fuel-salt jacket having a ceramic composite wall or a metal alloy wall, preferably a zirconium alloy, and

[0078] a cylindrical moderator and neutron reflector jacket, the moderator and neutron reflector jacket surrounding the fuel salt jacket, the moderator and neutron reflector jacket axially extending from the liquid moderator and neutron reflector inlet to the moderator and neutron reflector outlet to serve as a passage for a second liquid moderator and neutron reflector, the moderator and neutron reflector jacket having a metal alloy wall or a ceramic composite material wall, preferably, the metal alloy is a zirconium alloy.

[0079] The choice of material for the container and the fourth aspect ensure that the container has a relatively low absorption rate of neutrons while still providing good resistance to molten salts and moderator liquids.

[0080] In a possible implementation form of the fourth aspect, the nuclear reactor core includes a cylindrical first insulating jacket located between the central moderator container and the fuel salt jacket, and the first insulating jacket includes graphite felt or graphite felt impregnated with insulating aerogel, or includes other high-temperature insulating materials, such as ceramic fiber insulating material.

[0081] In a possible implementation form of the fourth aspect, the nuclear reactor core includes a second insulating jacket in a cylindrical shape located between the fuel salt jacket and the moderator neutron reflector jacket, and the second insulating jacket includes graphite felt or graphite felt impregnated with insulating aerogel.

[0082] In a possible implementation form of the fourth aspect, the liquid moderator and neutron reflector are heavy water or molten hydroxide, preferably molten enriched 7-deuterium lithium oxide salt (7LiOD).

[0083] In a possible implementation form of the fourth aspect, the control rods comprise a neutron absorbing material, which is preferably boron or hafnium.

[0084] In a possible implementation form of the fourth aspect, the fuel salt includes a fissile component, preferably includes enriched lithium 7 fluoride, thorium tetrafluoride, uranium tetrafluoride, uranium trifluoride and / or plutonium trifluoride ThF4-UF4-UF4-UF3-PuF3 salt.

[0085] In a possible implementation form of the fourth aspect, the blanket is a molten salt comprising a convertible component, preferably comprising enriched lithium fluoride and / or thorium tetrafluoride 7LiF-ThF4 salt.

[0086] According to a fifth aspect, a molten salt nuclear reactor is provided, comprising a nuclear reactor core according to the fourth aspect or according to any possible implementation of the fourth aspect.

[0087] According to a sixth aspect, there is provided a method of operating a molten salt nuclear reactor core, the nuclear reactor core comprising:

[0088] - a cylindrical tubular central moderator and neutron reflector container, said central moderator and neutron reflector container serving as a passage for a first liquid moderator and neutron reflector extending axially from a liquid moderator and neutron reflector inlet of said central moderator and neutron reflector container to a liquid moderator and neutron reflector outlet of said central moderator and neutron reflector container,

[0089] a cylindrical fuel-salt jacket surrounding the central moderator vessel, the fuel-salt jacket extending axially from a fuel-salt inlet of the cylindrical fuel-salt jacket to a fuel-salt outlet of the cylindrical fuel-salt jacket for passage of molten fuel-salt, and

[0090] a cylindrical moderator and neutron reflector jacket, the cylindrical moderator and neutron reflector jacket surrounding the fuel-salt jacket, the moderator and neutron reflector jacket axially extending from a liquid moderator and neutron reflector inlet of the cylindrical moderator and neutron reflector jacket to a moderator and neutron reflector outlet of the cylindrical moderator and neutron reflector jacket to serve as a passage for a second liquid moderator and neutron reflector,

[0091] The first liquid moderator and neutron reflector and the second liquid moderator and neutron reflector are hydroxide moderators,

[0092] Characterized in that the method comprises:

[0093] - controlling the temperature of the fuel salt in the fuel salt jacket to be maintained at a temperature between about 600° C. and 700° C.,

[0094] - controlling the temperature of the first liquid moderator and neutron reflector in the central moderator and neutron reflector container to be maintained at a temperature between about 200° C. and 700° C., and

[0095] - controlling the temperature of the second liquid moderator and neutron reflector in the moderator and neutron reflector jacket to be maintained at a temperature between about 200°C and 700°C.

[0096] The above objectives and other objectives are achieved through various aspects of the present disclosure. More possible implementation forms are obvious from, for example, the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0097] In the following detailed portion of the present disclosure, various aspects, embodiments and implementations will be explained in more detail with reference to exemplary embodiments shown in the accompanying drawings, in which:

[0098] Figure 1 is a schematic diagram of a molten salt reactor having a nuclear reactor core according to an embodiment;

[0099] Figure 2 is a front view of a nuclear reactor core according to an embodiment,

[0100] Figure 3 yes Figure 2 Cross-section of a nuclear reactor core, including magnified details,

[0101] Figure 4 yes Figure 2 Cross-section of a nuclear reactor core, including magnified details,

[0102] Figure 5 yes Figure 2 elevation and cross-sectional views of a portion of a nuclear reactor core, and

[0103] Figure 6 yes Figure 2 A front view and a cross-sectional view of a portion of a nuclear reactor core, and the remaining portion of the nuclear reactor core not cross-sectionally shown,

[0104] Figure 7 is a front view of a nuclear reactor core according to another embodiment,

[0105] Figure 8 yes Figure 7 A cross-sectional view of a nuclear reactor core.

[0106] Fig. 9 yes Figure 7 A cross-sectional view of a nuclear reactor core.

[0107] Fig.10 yes Figure 7Isolated elevation view of the fuel-salt jacket of a nuclear reactor core.

[0108] Fig.11 yes Fig.10 A separate bottom view of the fuel-salt jacketed vessel, and

[0109] Fig.12 is a cutaway elevational view of another embodiment of a nuclear reactor core. DETAILED DESCRIPTION

[0110] Figure 1 An embodiment of a molten salt nuclear reactor 100 using an embodiment of a nuclear reactor core 1 is illustrated. The molten salt nuclear reactor 100 uses a plurality of flowers 2 (pumps) to circulate molten fuel salt. Each flower 2 is connected to a heat exchanger 3 via a fuel salt loop 4, a reactor coolant loop 5, and a secondary coolant loop 6 for heat exchange with the nuclear reactor core 1. The fuel salt loop 4 provides fuel salt for driving and controlling the nuclear reaction. In addition, the heat exchanger 3 provides reactor coolant and secondary coolant via the fuel salt loop 4, the reactor coolant loop 5, and the secondary coolant loop 6. In order to circulate the flow of the molten salt and drive the flow of the molten salt, a flower 2 (pump) is used.

[0111] Reference Figures 2 to 6 , an embodiment of a nuclear reactor core 1 is shown with an inlet and / or outlet region 7 at the upper end and with an inlet and / or outlet region 8 at the lower end.

[0112] The nuclear reactor core 1 has an axis X, and the nuclear reactor core 1 extends along the axis X extending between an inlet and / or outlet region 7 and an inlet and / or outlet region 8 .

[0113] In the illustrated embodiment, the nuclear reactor core 1 is generally cylindrical, and a portion of the nuclear reactor core 1 is generally spherical. The nuclear reactor core 1 has a cylindrical and concentric structure. The tubular central moderator and neutron reflector container 10 extends along the axis X. In the present embodiment, the tubular central moderator and neutron reflector container 10 is generally cylindrical. The tubular central moderator and neutron reflector container 10 is configured to serve as a passage for liquid moderator and neutron reflector 11 between the liquid moderator and neutron reflector inlet 12 and the liquid moderator and neutron reflector outlet 13. The liquid moderator and neutron reflector can be heavy water or a molten hydroxide, such as a molten enriched 7-deuterium oxide lithium salt (7LiOD) or sodium hydroxide or potassium hydroxide or a mixture thereof.

[0114] The central moderator and neutron reflector container 10 has a maximum internal cross-sectional area at a position midway between the liquid moderator inlet 12 and the liquid moderator and neutron reflector outlet 13. The internal cross-sectional area of ​​the central moderator and neutron reflector container 10 preferably increases gradually toward the position midway between the liquid moderator and neutron reflector inlet 12 and the liquid moderator and neutron reflector outlet 13, and the internal cross-sectional area of ​​the central moderator and neutron reflector container 10 preferably changes continuously between the moderator and neutron reflector inlet 12 and the moderator and neutron reflector outlet 13. Therefore, for a cylindrical embodiment, the central moderator and neutron reflector container 10 has a varying inner radius. The inner radius can be varied to achieve a hemispherical shape of the cylindrical central moderator and neutron reflector container 10. Central moderator and neutron reflector container 10 has a variable inner radius R11 and outer radius R12, which are preferably the largest at or near the middle position and gradually decrease from the middle position. During operation of nuclear reactor core 1, central moderator and neutron reflector container 10 is at least partially filled with or fully filled with liquid moderator neutron reflector 11, and the liquid moderator and neutron reflector 11 are exchanged at a controlled rate by flowing through moderator and neutron reflector container 10.

[0115] In an embodiment, the cylindrical central moderator and neutron reflector container 10 is a metal alloy wall or a ceramic composite wall, the metal alloy is preferably an iron alloy (when the moderator and neutron absorbing liquid are heavy water), preferably stainless steel, and most preferably a zirconium alloy. In an embodiment, the ceramic composite is a ceramic matrix composite. The ceramic matrix composite includes ceramic fibers embedded in a ceramic matrix. Both the fiber and the matrix can include any ceramic material, whereby carbon and carbon fibers can also be considered ceramic materials. In an embodiment, the ceramic composite is a composite of silicon carbide and carbon, such as a carbon fiber-carbon matrix (C / C) composite, a silicon carbide fiber-silicon carbide matrix (SiC / SiC) composite, or a silicon carbide fiber-carbon matrix (SiC / C) composite.

[0116] The cylindrical fuel salt jacket extends along the axis X between the inlet and outlet regions 7, 8 and surrounds the central moderator and neutron reflector container 10. The fuel salt jacket is formed by assembling a plurality of tubular fuel salt containers 20. Each tubular fuel salt container 20 extends axially from a fuel salt inlet 22 to a fuel salt outlet 23 to serve as a passage for molten fuel salt 21. Each fuel salt container 20 in the fuel salt jacket is substantially identical to the other fuel salt containers 20 in the fuel salt jacket. During operation of the nuclear reactor core 1, the fuel salt jacket 20 is at least partially or completely filled with fuel salt 21, and the fuel salt 21 is exchanged at a controlled rate by flowing through the fuel salt container 20.

[0117] A cylindrical first insulating jacket is provided between the central moderator container 10 and the fuel salt jacket. The first insulating jacket is formed by one or more first insulating members 15. As shown in the figure, the first insulating member 15 can be formed as a sector-shaped piece similar to the cylindrical first insulating jacket. Alternatively, the first insulating member 15 can be formed as a strip-shaped piece spirally wound around the central moderator container 10. In an embodiment, the first insulating member 15 is made of graphite felt or graphite felt impregnated with insulating aerogel. The first insulating jacket 15 allows the heat loss of the moderator and neutron reflector liquid 11 to be greatly reduced, and the moderator and neutron reflector liquid 11 are always kept running at a much lower temperature than the fuel salt.

[0118] The cylindrical fuel-salt jacket is shaped to match the shape of the cylindrical central moderator and neutron reflector container 10 (with the first insulating jacket therebetween), i.e., to complement each other. Therefore, the inner radius of the fuel-salt jacket varies in a similar manner to the outer radius of the cylindrical central moderator and neutron reflector container 10, so that the first insulating jacket 15 is installed between the two.

[0119] The fuel salt jacket is formed as an annular hollow cylindrical member having a variable inner radius R21 and an outer radius R22. The fuel salt container 20 is preferably formed as an annular cylindrical sector having a variable inner radius R21 and an outer radius R22, respectively, and a given sector angle A2, wherein the inner radius R21 and the outer radius R22 are preferably the largest at or near the middle position and gradually decrease from the middle position. In the present embodiment, the sector angle is the same for all elements of the nuclear reactor core 1, and thus the sector angle is between Figure 4 However, it should be understood that the fan angle "An" need not be the same for different jackets, or even for different containers constituting a single jacket.

[0120] The fuel-salt jacket is a substantially circumferentially continuous jacket formed by mating sides of the tubular fuel-salt container 20 contacting each other along a majority of their axial extents.

[0121] The cylindrical moderator and neutron reflector jacket surrounds the cylindrical fuel salt jacket. The cylindrical moderator and neutron reflector jacket is formed by assembling a plurality of tubular moderator and neutron reflector containers 30. Each tubular moderator and neutron reflector container 30 extends axially from a liquid moderator and neutron reflector inlet 32 ​​to a liquid moderator and neutron reflector outlet 33 to serve as a passage for liquid moderator and neutron reflector 31. The elements constituting the tubular moderator and neutron reflector container 30 have a ceramic composite wall or a metal alloy wall, and the metal alloy is preferably a zirconium alloy. In an embodiment, the ceramic composite is a ceramic matrix composite. The ceramic matrix composite includes ceramic fibers embedded in a ceramic matrix. Both the fiber and the matrix can include any ceramic material, whereby carbon and carbon fibers can also be considered as ceramic materials. In an embodiment, the ceramic composite material is a composite material of silicon carbide and carbon, such as a carbon fiber-carbon matrix (C / C) composite material, a silicon carbide fiber-silicon carbide matrix (SiC / SiC) composite material, and or a silicon carbide fiber-carbon matrix (SiC / C) composite material. In an embodiment, each moderator neutron reflector container 30 in the moderator neutron reflector jacket 30 is substantially identical to the other moderator neutron reflector containers 30 in the fuel salt jacket.

[0122] The moderator and neutron reflector jacket is formed as an annular hollow cylindrical member with a variable inner radius R31 and an outer radius R32. The moderator neutron reflector container 30 is formed as an annular cylindrical sector with a variable inner radius R31 and an outer radius R32 and a given sector angle A3. The inner radius R31 and the outer radius R32 are the largest at or near the middle position, and gradually decrease from the middle position.

[0123] During operation of the nuclear reactor core 1 , the moderator and neutron reflector jacket is at least partially filled with or completely filled with liquid moderator neutron reflector 31 , and the liquid moderator and neutron reflector 31 are exchanged at a controlled rate by flowing through the moderator and neutron reflector container 30 .

[0124] A cylindrical second insulating jacket is provided between the fuel salt jacket and the moderator and neutron absorption jacket. The second insulating jacket is formed by one or more second insulating members 25. As shown in the figure, the second insulating member 25 can be formed as a sector-shaped piece similar to the cylindrical second insulating jacket. Alternatively, the second insulating member 25 can be formed as a strip-shaped piece spirally wound around the fuel salt jacket. In an embodiment, the second insulating member 25 is made of graphite felt or graphite felt impregnated with insulating aerogel. The second insulating jacket allows the heat loss of the moderator and neutron reflector liquid 31 to be greatly reduced, and the moderator and neutron reflector liquid 31 are always kept running at a much lower temperature than the fuel salt 21.

[0125] The optional cladding salt jacket surrounds the moderator and the neutron absorption jacket, preferably with a third insulating jacket disposed therebetween. The cladding salt jacket comprises a plurality of tubular cladding salt containers 40, each of which extends axially from an inlet 42 to an outlet 43 to serve as a passage for molten cladding salt 41, or is configured without a cladding salt inlet and outlet for holding the molten cladding salt 41 in a fixed manner. The plurality of tubular cladding salt containers 40 are assembled to form a cylindrical cladding salt jacket surrounding the moderator and the neutron reflector jacket.

[0126] The cladding salt jacket is formed as an annular hollow cylindrical member having a variable inner radius R41 and an outer radius R42. The cladding salt container 40 is formed as an annular cylindrical sector having a variable inner radius R41 and an outer radius R42, respectively, and a given sector angle A4. The inner radius R41 and the outer radius R42 are maximum at or near the middle position and gradually decrease from the middle position. The cladding salt jacket can be constructed without a cladding salt inlet and outlet, wherein the cladding salt 41 is not continuously exchanged and can be kept in a molten state - close to its melting point to prevent the cladding salt from radiolysis - or a frozen state.

[0127] A cylindrical third insulating jacket is provided between the neutron reflector container and the cladding salt jacket. Preferably, the third insulating jacket is formed by one or more third insulating members 35. The third insulating member 35 is shaped as a sector-shaped piece similar to the cylindrical third insulating jacket, or is shaped as a strip-shaped piece spirally wound around the moderator and the neutron reflector jacket. Preferably, the third insulating member 35 is made of graphite felt or graphite felt impregnated with insulating aerogel.

[0128] In an embodiment (not shown), the insulating sheet is coated with sheet metal, e.g. 0.01 mm to 0.1 mm, to eliminate or at least reduce the risk of salt wicking into the insulation when the container is ruptured. In the insulating sheet, it would be difficult to release decay heat, which could cause the salt to boil and possibly increase pressure, i.e. a very undesirable situation.

[0129] In an embodiment, the fuel salt container 20, the moderator and neutron reflector container 30 and / or the cladding salt container 40 are respectively assembled from two parts, which are separated by a symmetry plane M extending radially (in a radial direction relative to the axis A) from a middle position. As shown in the figure, the inlet section and the outlet section of these containers 20, 30 and 40 can be bent radially outward and provided with flanges or the like for connection with a pipeline. However, it should be understood that the inlet section and the outlet section can also extend axially and there is no need to provide flanges for connection with a pipeline, because other solutions for connecting the containers 20, 30 and 40 to a pipeline are known in the art. In an embodiment, the inlet 12 and the outlet 13 of the moderator and neutron reflector container 10 are provided with flanges for connection with a pipeline, but it can be understood that the inlet 12 and the outlet 13 may not be formed with flanges and connected to the pipeline by another assembly form.

[0130] The containers 20, 30 and 40 and possibly their inlet and outlet sections are held together by a structure which, for the sake of simplicity, is not shown in the drawings. Such support structures are well known in the art.

[0131] The design of the nuclear reactor core 1 is intended to obtain a nuclear reactor core that is as spherical as possible, but whose material can still withstand the harsh conditions in the nuclear reactor core 1 while allowing a sufficient fuel salt circulation rate to extract the generated heat. Therefore, the designed structure is both cylindrical and spherical, and both a layered structure and a segmented structure, that is, a mixture of the layered structure and shape of an onion and the segmented structure and shape of a citrus fruit.

[0132] Traditional ceramics are relatively brittle, have relatively low thermal shock resistance and relatively low fracture toughness. Ceramic composites or ceramic matrix composites are made of short, continuous or woven ceramic fiber materials, which are usually embedded in a ceramic matrix to reinforce the matrix ceramic. Ceramic composites can overcome or at least reduce the shortcomings of traditional ceramics.

[0133] The fibers and matrix are made of various ceramic materials, and the processes are different, so there are differences in mechanical properties such as strength, porosity and impurity content. Most of the common ceramic composites on the market are made of carbon and / or silicon carbide fibers and carbon or silicon carbide matrices, referred to as (C / C), (C / SiC), (SiC / C) and (SiC / SiC). Naturally occurring carbon containing mainly carbon 12 isotopes and silicon containing mainly silicon 28 isotopes have a low neutron capture probability in the thermal neutron energy spectrum. In addition, both carbon and silicon carbide have good corrosion resistance to molten salts used in molten salt reactors, that is, both are resistant to corrosion to molten salts and have low neutron absorption rates in the thermal energy spectrum. However, both materials are too brittle to be used as construction materials for containers and jackets in the core of molten salt nuclear reactors. However, their ceramic composites are interesting candidates for use as construction materials in molten salt reactors due to their relatively high fracture toughness and strong thermal shock resistance, combined with low neutron absorption in the thermal spectrum and excellent resistance to radiation damage.

[0134] The construction of the container (moderator and neutron reflector container 10 and / or moderator and neutron reflector container 30 and / or fuel salt container 20 and / or cladding salt container 40) from ceramic composite materials includes laying and fixing, wherein ceramic fibers or resin-impregnated ceramic fibers are wound or placed in or around a mold / core so that the component has the shape of the final ceramic composite component, and then the polymer is infiltrated into the fibers, and then the component is cured. After curing, the component is demolded (removed from the mold / core), and the polymer is pyrolyzed in a furnace at high temperature, typically above 800°C, in an inert atmosphere to form a matrix composite (in an embodiment, the mold / core is a disposable mold / core that is burned, melted, crushed or destroyed after the first use). This will make the component porous, and the component is then re-impregnated (resin impregnated) and the pyrolysis step is repeated until the desired porosity is achieved.

[0135] There are several minor variations of the above process, but all of them depend on the first step of shaping the fibers and polymer in a mold and / or on a core. This limits the geometries of the jackets, containers and other components that can be manufactured, because the jackets, containers and other components of the nuclear reactor core 1 must be able to be released from the mold or fixture (core material) in the final shape of the container, allowing for some intermediate processing or final processing to achieve tolerance requirements. Compared with traditional metal manufacturing processes such as casting, forming (e.g., forging, rolling, extrusion, die forming, coining, stretching, drawing, stamping and bending) and machining (e.g., turning, drilling, boring, milling and cutting), this process does not allow for the manufacture of complex shapes, but is more technically challenging than machining conventional metal parts. However, the disclosed structure and geometry of the present nuclear reactor core allow each of the container and jacket to be manufactured by processes used for the manufacture of components in composite ceramic materials that are currently available on the market.

[0136] In an embodiment (not shown in the drawings), the central moderator container 10 is segmented and formed by a plurality of tubular moderator containers, each extending axially from a moderator inlet to a moderator outlet to serve as a passage for supplying the moderator, and a plurality of tubular moderator containers are assembled to form the central moderator container 10. In a variation of this embodiment, the central moderator container 10 has a circumferential outer wall and a circumferential inner wall, the circumferential inner wall forming a cavity for receiving a control rod. The control rod is made of a neutron absorbing material such as boron or hafnium.

[0137] In an embodiment (not shown in the drawings), the second fuel salt jacket surrounds the moderator and neutron reflector jacket, and the second moderator and neutron reflector jacket surrounds the second fuel salt jacket. In this embodiment, if a cladding jacket is present, the cladding jacket surrounds the second neutron reflector jacket. In this embodiment, the second fuel salt jacket is formed by a plurality of tubular fuel salt containers, each extending axially from the fuel salt inlet to the fuel salt outlet to serve as a passage for molten fuel salt 21, and the plurality of tubular containers are assembled together to form a cylindrical second fuel salt jacket surrounding the moderator and neutron reflector jacket. The second neutron reflector jacket is formed by a plurality of tubular moderator and neutron reflector containers. Each tubular moderator neutron reflector container extends axially from the liquid moderator and neutron reflector inlet to the liquid moderator and neutron reflector outlet to serve as a passage for the liquid moderator and neutron reflector.

[0138] In an embodiment (not shown), the nuclear reactor core is provided with a movable neutron absorption control element between the containers of the jacket, preferably between the containers constituting the fuel salt jacket and / or between the containers forming the jacket surrounding the fuel jacket or surrounded by the fuel jacket. The neutron absorption control element is similar to a control rod, but the neutron absorption control element is not rod-shaped, but is shaped like a plate or wedge to match the adjacent container in the relevant jacket, and the neutron absorption control element is arranged so that the neutron absorption control element can be inserted into the nuclear reactor core 1 and retracted from the nuclear reactor core 1 for controlling the nuclear reactivity of the nuclear reactor core.

[0139] In an embodiment, the reactivity of the nuclear chain reaction of the nuclear reactor core 1 is controlled by controlling the temperature of the fuel salt in the fuel salt jacket to be maintained between about 600° C. and 700° C., and controlling the moderator and neutron reflector liquid in the central moderator and neutron reflector container 10 to be maintained between about 10° C. and 90° C. Preferably, the temperature of the moderator and neutron reflector liquid 21 in the moderator and neutron reflector jacket 20 is also controlled to be maintained between about 10° C. and 90° C.

[0140] The method for controlling the reactivity of the nuclear chain reaction and the temperature of the nuclear reactor core 1 may also include:

[0141] - regulating the level or quality of the liquid moderator and neutron reflector 11 in the central moderator and neutron reflector container 10, and / or

[0142] - regulating the level or quality of the moderator and neutron reflector 31 in the moderator and neutron reflector jacket 30, and / or

[0143] - regulating the level or quality of the molten cladding salt 41 in the cladding salt jacket 40, and / or

[0144] - regulating the temperature of the fuel salt 21 passing through the fuel jacket 20, and / or

[0145] - regulating the temperature of the liquid moderator and neutron reflector 11 in the central moderator and neutron reflector container 10, and / or

[0146] - regulating the temperature of the liquid moderator and neutron reflector 31 in the central moderator and neutron reflector jacket 30, and / or

[0147] - adjusting the chemical composition of the fuel salt 21, and / or

[0148] - adjusting the chemical composition of the liquid moderator and the neutron reflector 11, 31, and / or

[0149] - adjusting the position of a control rod at least partially inserted into the cavity of the central moderator and neutron reflector container 10, and / or

[0150] - adjusting the position of control rods at least partially inserted between the fuel-salt containers 20, and / or

[0151] - Adjusting the position of a control rod at least partially inserted between the moderator and the neutron absorber vessel 30.

[0152] Increasing the level or mass of liquid moderator and neutron reflector in central moderator and neutron reflector vessel 10 increases the reactivity of the nuclear chain reaction by providing more moderation and / or reflection, and vice versa.

[0153] Increasing the level or mass of liquid moderator and neutron reflector in moderator and neutron reflector jacket 30 increases the reactivity of the nuclear chain reaction by providing more moderation and / or reflection and / or by providing less neutron leakage, and vice versa.

[0154] Increasing the level or mass of molten cladding salt 41 in the cladding salt jacket 40, if present, increases the reactivity of the nuclear chain reaction by providing more reflections and / or less neutron leakage, and vice versa. Since the flow rate may be quite high, the surface of the liquid may have waves, bubbles and foam / foam, so the liquid may not always have a good flat surface for determining the amount of liquid in the relevant container. In addition, if liquid moderator is flowing or sprayed in the relevant container, the flow or droplets of liquid moderator will help moderation. Therefore, in an embodiment, it is the mass of the liquid in the relevant container that is adjusted.

[0155] Increasing the temperature of the fuel salt in the fuel salt jacket 20 reduces the reactivity of the nuclear chain reaction by providing a lower average density in the nuclear reactor core and thus less fissile fuel, and vice versa.

[0156] Increasing the temperature of the liquid moderator and neutron reflector in the central moderator and neutron reflector vessel 10 reduces the reactivity of the nuclear chain reaction by providing a lower average density in the nuclear reactor core and thus more moderation and / or reflection, and vice versa.

[0157] Increasing the temperature of the liquid moderator and neutron reflector in the moderator and neutron reflector jacket reduces the reactivity of the nuclear chain reaction by providing a lower average density in the nuclear reactor core and thus providing more moderation and or neutron reflectivity, and / or providing more neutron leakage, and vice versa.

[0158] Adding fissile material to the fuel salt 21 increases the reactivity of the nuclear chain reaction, and vice versa.

[0159] Adding convertible materials such as thorium or neutron absorbing materials to the fuel salt 21 reduces the reactivity of the nuclear chain reaction, and vice versa.

[0160] Adding convertible materials such as thorium or neutron absorbing materials to the moderator and reflective liquids 11, 31 reduces the reactivity of the nuclear chain reaction, and vice versa.

[0161] The temperature of the corresponding moderator liquid 11, 31 or fuel salt 21 can be changed by, for example:

[0162] - increasing the flow rate, thereby reducing the temperature drop in the nuclear reactor core 1 and thus increasing or decreasing the density, and / or

[0163] - regulating the cooling rate of the moderator liquid 11, 31 or the fuel salt 21 outside the nuclear reactor core 1, thereby changing the average temperature of the nuclear reactor core 1 and thus increasing or decreasing the density.

[0164] The level or mass of the corresponding moderator liquid 11, 31 or fuel salt 21 or molten cladding salt 41 is changed by, for example, adjusting the rate at which the liquid is pumped into the corresponding container or jacket from the top and the rate at which the liquid is passively discharged from the bottom.

[0165] In an embodiment (not shown), a controller, such as an electronic control unit, is coupled to elements of the molten salt nuclear reactor 100 and is configured to control the reactivity of the nuclear reactor core 1 according to the above-described measures.

[0166] The above embodiment is described for a reactor core in which the central moderator and neutron reflector vessel 10, and the fuel salt jacket, and the neutron reflector jacket, and - if present - the cladding salt jacket 41 have a cross-sectional profile close to a perfect ring.

[0167] Figures 7 to 11Another embodiment of a nuclear reactor core 1 is illustrated. In this embodiment, for simplicity, structures and features that are the same or similar to corresponding structures and features previously described or shown herein are represented by the same reference numerals as before. In this embodiment, the central moderator and neutron reflector container, the fuel salt jacket, the neutron reflector jacket, and - if present - the cladding salt jacket have a polygonal cross-sectional profile. The polygonal cross-sectional profile preferably has at least three sides so that the profile is close to an annular profile, that is, the profile is close to an annular profile, and the resulting container and jacket have a generally cylindrical shape with a corresponding effective radius. The illustrated embodiment has eight sides and is therefore similar to an octagon, but it should be understood that any number of sides above four can be used. In this embodiment, the first, second and third insulation jackets 15, 25, 35 are not shown in the drawings, but it is understood that these insulation jackets 15, 25, 35 can be included in this embodiment.

[0168] The central moderator and neutron reflector container 10 has a variable inner effective radius R11' and an outer effective radius R12'. Preferably, the inner effective radius R11' and the outer effective radius R12' are the largest at or near the middle position and gradually decrease from the middle position. In this embodiment, the effective radius is the radius of the circle that is closest to the cross-sectional polygonal profile of the relevant element.

[0169] The fuel-salt jacket is formed as a hollow annular cylindrical member having a variable inner effective radius R21' and an outer effective radius R22'. The fuel-salt container 20 is preferably formed as a substantially annular cylindrical sector having a variable inner effective radius R21' and an outer effective radius R22' and a given sector angle A2, respectively, the inner effective radius R21' and the outer effective radius R22' being preferably the largest at or near the middle position and gradually decreasing from the middle position.

[0170] The moderator and neutron reflector jacket is formed as a hollow substantially annular cylindrical member having a variable inner effective radius R31' and an outer effective radius R32'. The moderator neutron reflector container 30 is formed as a sector-shaped member in the shape of an annular cylinder having a respectively variable inner effective radius R31' and an outer effective radius R32' and a given sector angle A3. The inner effective radius R31' and the outer effective radius R32' are the largest at or near the middle position, and gradually decrease from the middle position.

[0171] The cladding salt jacket is formed as a hollow substantially annular cylindrical member having a variable inner effective radius R41' and an outer effective radius R42'. The cladding salt container 40 is formed as a sector-shaped member in the shape of an annular cylinder having a variable inner effective radius R41' and an outer effective radius R42' and a given sector angle A4, respectively. The inner effective radius R41' and the outer effective radius R42' are the largest at or near the middle position and gradually decrease from the middle position.

[0172] By using containers and claddings with a polygonal cross-sectional profile, the sheet material forming the surface of these elements does not need to be bent in both directions, i.e. it can be bent in one direction, which is an advantage for elements made of sheet metal, since it is much easier and more efficient to bend sheet metal in only one direction than to bend it in two directions to produce a double-curved sheet metal. Sheet metal bent in one direction can be produced very simply, for example using rollers, while sheet metal bent in both directions usually requires special dies, which greatly increases the production costs. Elements made of sheet metal are manufactured by assembling a plurality of bent sheet metals by welding them along the seams. Preferably, such sheet metal is relatively thin, for example 1 mm to 2 mm.

[0173] Fig. 9 The fuel salt jacket is shown to be composed of a plurality of tubular fuel salt containers 20. Each tubular fuel salt container 20 ( Fig.10 5 ) is formed by a plurality of bent sheet metal parts connected by welding 51. In the inlet / outlet region 7, the fuel-salt jacket is connected to an outlet element 24, preferably substantially at right angles, welded to the fuel-salt jacket. The outlet element 24 comprises a fuel-salt outlet 23 and is connected to the tubular fuel-salt container 20 of the fuel-salt jacket. The outlet element 24 can be made of the same material as the tubular fuel-salt container 20, preferably a plate-like material. In the inlet / outlet region 8, the fuel-salt jacket is connected to an inlet element 26, substantially at right angles, welded to the fuel-salt jacket. The inlet element 26 comprises a fuel-salt inlet 22 and is connected to the tubular fuel-salt container 20 of the fuel-salt jacket. The inlet element 26 can be made of the same material as the tubular fuel-salt container 20, preferably a plate-like material.

[0174] Back to Figure 8 The central moderator and neutron reflector container 10, which is basically tubular and cylindrical, is provided with a basically right-angled inlet element 17 in the inlet / exit area 7, which inlet element includes a liquid moderator and neutron reflector inlet 12, and is provided with a basically right-angled outlet element 18 in the inlet / exit area 8, which outlet element includes a liquid moderator and neutron reflector outlet 13.

[0175] The moderator and neutron reflector jacket is provided with a substantially right-angled inlet element in the inlet / outlet region 7, which inlet element includes a liquid moderator and neutron reflector inlet 32, and a substantially right-angled inlet element is provided in the inlet / outlet region 8, which inlet element includes a liquid moderator and neutron reflector outlet 33.

[0176] The cladding jacket is provided with a substantially right-angled outlet element in the inlet / outlet region 7 , which outlet element comprises a cladding salt outlet 43 , and with a substantially right-angled inlet element in the inlet / outlet region 8 , which inlet element comprises a cladding salt inlet 42 .

[0177] Fig.12 1 is a cross-sectional front view of another embodiment of a nuclear reactor core. In this embodiment, for simplicity, structures and features that are the same or similar to corresponding structures and features previously described or shown herein are denoted by the same reference numerals as before. Fig.12 The implementation method and Figures 7 to 11 The embodiment of the invention is basically the same, except that the diameter / cross-sectional area of ​​the container and the jacket does not change in the entire axial range. Alternatively, the part of the axial range close to the inlet / outlet regions 7 and 8 has a constant cross-sectional area.

[0178] In embodiments (not shown), the container made of composite material or metal has added reinforcements to improve mechanical properties. The reinforcements may be formed by internal struts or ribs, internal or external "isogrids" or "positive grids" and the like. In embodiments, the jacketed container is held together by welds, latches or straps, for example, extending around the segments like a ring (hoop) around a barrel holds the staves together, wherein the jacketed container is held together in a manner similar to how staves of a barrel are held together.

[0179] In an embodiment (not shown), the container is made of metal and is surrounded by a composite cage that is made to provide mechanical support and stability to the metal container. In such an embodiment, the absorption of neutrons by the metal can be reduced by using a low neutron absorption composite material to provide some or most of the mechanical integrity.

[0180] In embodiments using water or heavy water as the liquid moderator, small amounts of 7LiOD or other hydroxides or deuterium oxides are added to control pH, as is common in many solid fuel and heavy moderator reactors.

[0181] In embodiments using water or heavy water as the liquid moderator, a large amount of 7LiOD or other hydroxides, deuterium oxides or other salts are added to suppress the melting point of the liquid moderator, thereby allowing low temperature operation or greater solidification margin. Lowering the melting point increases the density of the liquid moderator and thus improves the moderation capacity, but also shifts the reactor neutron spectrum toward lower energies, in which case the neutron reproduction factor may increase for a particular fission fuel.

[0182] In embodiments using water or heavy water as the liquid moderator, an active or passive recombinator is used to recombinate any gases produced from the radioactive decomposition of the liquid moderator.

[0183] Various aspects and implementations have been described herein in conjunction with various embodiments. However, other variations of the disclosed embodiments may be understood and implemented by a person skilled in the art through study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0184] The reference signs used in the claims should not be construed as limiting the scope. Unless otherwise indicated, the drawings have been read together with the specification (e.g., section lines, arrangement of components, proportions, extent, etc.) and are considered part of the entire written description of the present disclosure. The terms "horizontal", "vertical", "left", "right", "upper" and "lower", as well as their adjective and adverb derivatives (e.g., "horizontally", "to the right", "upward", etc.) used in the description, refer only to the direction of the illustrated structure when a particular drawing faces the reader. Similarly, the terms "inward" and "outward" generally refer to the direction of a surface relative to its axis of extension or axis of rotation, as the case may be.

Claims

1. A nuclear reactor core (1) for a molten salt nuclear reactor (100), the nuclear reactor core (1) comprising: - a cylindrical tubular central moderator and neutron reflector container (10) which serves as a passage for liquid moderator and neutron reflector (11) extending axially from a liquid moderator and neutron reflector inlet (12) of the central moderator and neutron reflector container (10) to a liquid moderator and neutron reflector outlet (13) of the central moderator and neutron reflector container (10), - a plurality of tubular fuel salt containers (20), each tubular fuel salt container (20) extending axially from a fuel salt inlet (22) of the tubular fuel salt container (20) to a fuel salt outlet (23) of the tubular fuel salt container (20) to serve as a passage for molten fuel salt (21), - a plurality of tubular moderator and neutron reflector containers (30), each tubular moderator and neutron reflector container (30) extending axially from a liquid moderator and neutron reflector inlet (32) of the moderator and neutron reflector container (30) to a liquid moderator and neutron reflector outlet (33) of the moderator and neutron reflector container (30) to serve as a passage for the liquid moderator and neutron reflector (31), The nuclear reactor core (1) is characterized in that: A plurality of tubular fuel-salt containers (20) are assembled to form a cylindrical fuel-salt jacket surrounding the central moderator and neutron reflector container (10). A plurality of tubular moderator and neutron reflector vessels (30) are assembled to form a cylindrical moderator and neutron reflector jacket surrounding the cylindrical fuel-salt jacket, and wherein the cylindrical central moderator and neutron reflector vessel (10) has a maximum internal cross-sectional area at a position intermediate between the liquid moderator and neutron reflector inlet (12) of the central moderator and neutron reflector vessel (10) and the liquid moderator and neutron reflector outlet (13) of the central moderator and neutron reflector vessel (10).

2. The nuclear reactor core (1) according to claim 1, wherein: The inner cross-sectional area of ​​the central moderator and neutron reflector container gradually increases toward the intermediate position between the liquid moderator and neutron reflector inlet (12) of the central moderator and neutron reflector container and the liquid moderator and neutron reflector outlet (13) of the central moderator and neutron reflector container.

3. The nuclear reactor core (1) according to claim 2, wherein: The internal cross-sectional area changes continuously between the liquid moderator and neutron reflector inlet (12) of the central moderator and neutron reflector container and the liquid moderator and neutron reflector outlet (13) of the central moderator and neutron reflector container.

4. A nuclear reactor core (1) according to any one of claims 1 to 3, wherein: The cylindrical central moderator and neutron reflector container (10) and / or the liquid moderator and neutron reflector container (30) have a wall of a metal alloy or a wall of a ceramic composite material.

5. The nuclear reactor core (1) according to claim 4, wherein: The metal alloy is an iron alloy or a zirconium alloy.

6. The nuclear reactor core (1) according to claim 4, wherein: The metal alloy is stainless steel.

7. A nuclear reactor core (1) according to any one of claims 1 to 3, wherein: The fuel salt container (20) has a wall of a ceramic composite material or a wall of a metal alloy.

8. The nuclear reactor core (1) according to claim 7, wherein: The metal alloy is an iron alloy or a nickel alloy.

9. The nuclear reactor core (1) according to claim 8, wherein: The ferroalloy is stainless steel.

10. The nuclear reactor core (1) according to claim 8, wherein: The nickel alloy is Inconel or Hastelloy.

11. A nuclear reactor core (1) according to any one of claims 1 to 3, wherein: Each fuel-salt container (20) in the fuel-salt jacket is substantially identical to the other fuel-salt containers in the fuel-salt jacket.

12. A nuclear reactor core (1) according to any one of claims 1 to 3, wherein: Each moderator and neutron reflector vessel (30) in the moderator and neutron reflector jacket is substantially identical to the other moderator and neutron reflector vessels in the moderator and neutron reflector jacket.

13. A nuclear reactor core (1) according to any one of claims 1 to 3, wherein: A cylindrical first insulating jacket is provided between the central moderator and neutron reflector container (10) and the fuel-salt jacket, and the first insulating jacket is formed by one or more first insulating members (15), wherein the first insulating members (15) are shaped similar to sectors of the cylindrical first insulating jacket, or the first insulating members (15) are shaped as strips spirally wound around the central moderator and neutron reflector container (10).

14. A nuclear reactor core (1) according to claim 13, wherein: The first insulating member (15) is made of graphite felt or graphite felt impregnated with insulating aerogel.

15. A nuclear reactor core (1) according to any one of claims 1 to 3, wherein: A second insulating jacket having a cylindrical shape is arranged between the fuel-salt jacket and the moderator and neutron reflector jacket, and the second insulating jacket is formed by one or more second insulating members (25), and the second insulating members (25) are shaped similar to sectors of the second insulating jacket having a cylindrical shape, or the second insulating members (25) are shaped as strips spirally wound around the fuel-salt jacket.

16. A nuclear reactor core (1) according to claim 15, wherein: The second insulating member (25) is made of graphite felt or graphite felt impregnated with insulating aerogel.

17. A nuclear reactor core (1) according to any one of claims 1 to 3, comprising a plurality of tubular cladding salt containers (40), each of which extends axially from an inlet of the cladding salt container (40) to an outlet of the cladding salt container (40) to serve as a passage for molten cladding salt (41), and a plurality of tubular cladding salt containers (40) are assembled to form a cylindrical cladding salt jacket surrounding the moderator and neutron reflector jacket.

18. A nuclear reactor core (1) according to claim 17, wherein: A third insulating jacket having a cylindrical shape is arranged between the moderator and neutron reflector jacket and the cladding salt jacket, and the third insulating jacket is formed by one or more third insulating members (35), and the third insulating members (35) are shaped similar to the sectors of the third insulating jacket having a cylindrical shape, or the third insulating members (35) are shaped as strips spirally wound around the moderator and neutron reflector jacket.

19. A nuclear reactor core (1) according to claim 18, wherein: The third insulating member (35) is made of graphite felt or graphite felt impregnated with insulating aerogel.

20. The nuclear reactor core (1) according to claim 2, wherein: The nuclear reactor core comprises a plurality of tubular cladding salt containers (40), wherein the central moderator and neutron reflector container (10), the fuel salt container (20), the moderator and neutron reflector container (30), and / or the cladding salt container (40) are assembled from two parts, and the two parts are separated by a symmetry plane (M) extending radially from the middle position.

21. A nuclear reactor core (1) according to claim 20, wherein: The cladding salt container (40) has a wall of a ceramic composite material or a wall of a metal alloy.

22. A nuclear reactor core (1) according to claim 21, wherein: The metal alloy is an iron alloy or a nickel alloy.

23. A nuclear reactor core (1) according to claim 22, wherein: The ferroalloy is stainless steel.

24. A nuclear reactor core (1) according to claim 22, wherein: The nickel alloy is Inconel or Hastelloy.

25. The nuclear reactor core (1) according to claim 2, wherein: The central moderator and neutron reflector container (10) has a variable inner radius R11 and an outer radius R12.

26. A nuclear reactor core (1) according to claim 25, wherein: The inner radius R11 and the outer radius R12 are largest at or near the middle position and gradually decrease from the middle position.

27. A nuclear reactor core (1) according to any one of claims 1 to 3, wherein: The fuel-salt jacket is formed as an annular hollow cylindrical member having a variable inner radius R21 and an outer radius R22, and wherein the fuel-salt container (20) is formed as an annular cylindrical sector having a variable inner radius R21 and an outer radius R22 and a given sector angle A2, the inner radius R21 and the outer radius R22 being the largest at or near the middle position and gradually decreasing from the middle position.

28. A nuclear reactor core (1) according to claim 2, wherein: The moderator and neutron reflector jacket is formed as an annular hollow cylindrical member having a variable inner radius R31 and an outer radius R32, and wherein the moderator and neutron reflector container (30) is formed as an annular cylindrical sector having a variable inner radius R31 and an outer radius R32 and a given sector angle A3, wherein the inner radius R31 and the outer radius R32 are maximum at or near the middle position and gradually decrease from the middle position.

29. The nuclear reactor core (1) according to claim 17, wherein: The cladding salt jacket is formed as an annular hollow cylindrical member having a variable inner radius R41 and an outer radius R42, and wherein the cladding salt container (40) is formed as an annular cylindrical sector having a variable inner radius R41 and an outer radius R42, respectively, and a given sector angle A4, wherein the inner radius R41 and the outer radius R42 are maximum at or near the middle position and gradually decrease from the middle position.

30. The nuclear reactor core (1) according to claim 17, wherein: The fuel salt jacket, the moderator and neutron reflector jacket and / or the cladding salt jacket are substantially circumferentially continuous jackets, formed by matching sides of tubular vessels forming these jackets contacting each other along most of their axial extent.

31. A nuclear reactor core (1) according to any one of claims 1 to 3, wherein: The central moderator and neutron reflector container (10) is segmented and formed by a plurality of tubular moderator containers, each of which extends axially from a moderator inlet to a moderator outlet to serve as a passage for the moderator, and a plurality of tubular moderator containers are assembled to form the central moderator and neutron reflector container (10).

32. A nuclear reactor core (1) according to claim 31, wherein: The central moderator and neutron reflector container (10) has a circumferential outer wall and a circumferential inner wall.

33. A nuclear reactor core (1) according to claim 32, wherein: The circumferential inner wall forms a cavity for receiving a control rod.

34. A molten salt nuclear reactor (100) comprising a nuclear reactor core (1) according to any one of claims 1 to 33.

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