Small liquid-solid dual-fuel molten salt reactor core loaded with cross-shaped spiral fuel

Abstract

The invention discloses a small liquid-solid dual-fuel molten salt reactor core loaded with a cross spiral fuel, and relates to the technical field of nuclear reactor engineering. The reactor core of the small liquid-solid dual-fuel fused salt reactor loaded with the cross spiral fuel comprises two parts, namely an active area and a control drum, the control drum comprises a reflecting layer and a control drum absorbing material, the reflecting layer is made of beryllium oxide, and the control drum absorbing material is boron carbide with the boron 10 enrichment degree of 100%; the active area is composed of a fuel element and a fluoride salt coolant, and the whole active area is packaged in a shell made of Zr-4; the fuel element is in a cross spiral shape and is arranged in a regular hexagon shape, the fuel element is composed of an axial reflecting layer, fuel, a He cavity and an Re absorber, and the fuel is UC solid fuel with the U-235 enrichment degree being 45.684 wt.%; the material of the fluoride salt coolant is 7LiF-KF-UF4 (49.55 to 49.55 to 0.9 mol%), wherein the enrichment degree of U-235 in the UF4 is 30 percent by weight. According to the invention, the reactor core power density is further improved and the fuel peak temperature is effectively reduced while the reactor core heat is ensured to be discharged in time.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear reactor engineering, in particular to a small liquid-solid dual-fuel molten salt reactor core loaded with cross-helical fuel. Background Art

[0002] As a new type of nuclear reactor component fuel, the cross-spiral fuel has better thermal-hydraulic properties than traditional geometric shapes, can greatly improve the power density of the reactor, and has good application prospects in the development of new reactors.

[0003] With the development of the fourth-generation nuclear energy system, molten salt reactors have gradually become a research hotspot due to their high safety and high thermoelectric efficiency. At present, many molten salt reactor core design schemes have been proposed internationally, mainly using the flow of fluoride salts to achieve a cooling effect.

[0004] Traditional solid fuel is limited by the type of fuel rods and the coolant circuit design, which limits the reactor core miniaturization and the improvement of core power density. Therefore, a molten salt reactor core loaded with a new cross-helical fuel with liquid-solid dual fuel is needed to effectively solve the above problems. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a small liquid-solid dual-fuel molten salt reactor core loaded with cross-helical fuel.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: a small liquid-solid dual-fuel molten salt reactor core loaded with cross-spiral fuel, comprising a core active area, a control drum and a reflector layer;

[0007] The active zone includes fuel elements, fluoride salt coolant and a cladding that encapsulates the active zone. The fuel elements are arranged in a regular hexagon in the core active zone. There are 61 fuel elements in the core active zone, and the area between two adjacent fuel elements is a channel for the fluoride salt coolant.

[0008] Preferably, the material used for the fluoride salt coolant is 7LiF-KF-UF4 (49.55-49.55-0.9 mol), wherein the enrichment of U-235 in UF4 is 30 wt.%; and the material used for the cladding of the active zone is Zr-4.

[0009] Preferably, the fuel elements are of a cross-spiral type and are arranged in a hexagonal pattern in the core active area. The blades of adjacent fuel elements touch each other every 30 degrees of rotation, which means that every two adjacent fuel elements have five fixed points. A fuel element includes an axial reflection layer, a He gas cavity, solid fuel, a spectral shift absorber, and a fuel cladding that covers the fuel element.

[0010] Preferably, the material used for the axial reflection layer in the fuel element is beryllium oxide, the material filled in the He gas cavity is helium, the material used for the solid fuel is solid uranium carbide, in which the U-235 enrichment is 45.684wt.%, the material used for the spectral shift absorber is Re, and the material used for the fuel cladding is Zr-4.

[0011] Preferably, the control drum is embedded in the reflective layer, and there are 6 control drums uniformly distributed around the periphery of the core active area, and the control drum is rotatable.

[0012] Preferably, the main material of the control drum is beryllium oxide, and a neutron absorbing material is provided within a range of 120° on one side, and the neutron absorbing material is boron carbide with a boron 10 enrichment of 100%.

[0013] The present invention provides a small liquid-solid dual-fuel molten salt reactor core loaded with cross-spiral fuel. It has the following beneficial effects:

[0014] (1) The solid fuel element of the present invention adopts a cross-spiral solid fuel rod, which increases the surface area of ​​the fuel compared with the existing plate-type, cylindrical and spherical fuels. The spiral structure effectively enhances the mixing of the coolant, enhances the heat exchange effect, and improves the power density.

[0015] (2) In the small liquid-solid dual-fuel molten salt reactor core loaded with cross-spiral fuel, the solid fuel rods of the reactor core of the invention are arranged in a hexagonal manner, adjacent fuel rods can support each other to fix the fuel rods, and the hexagonal arrangement has a high space utilization rate, which is conducive to reducing the core volume.

[0016] (3) The core of the small liquid-solid dual-fuel molten salt reactor loaded with cross-spiral fuel adopts a solid-liquid dual-fuel design, using liquid fuel / coolant 7LiF-KF-UF4 (49.55-49.55-0.9mol%), adding a small amount of U-235 to the molten salt coolant, and using the thermal expansion effect to adjust the negative feedback coefficient of the core. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a radial schematic diagram of the core of a molten salt reactor;

[0018] Figure 2 It is a schematic diagram of the axial core of a molten salt reactor;

[0019] Figure 3 This is a schematic diagram of the fuel element.

[0020] In the figure: 1. core active region; 2. control drum; 3. reflection layer; 1-1. fuel element; 1-2. fluoride salt coolant; 1-3. cladding of active region; 1-1-1. axial reflection layer; 1-1-2. He gas cavity; 1-1-3. solid fuel; 1-1-4. spectral shift absorber; 1-1-5. fuel cladding. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0022] Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0023] Example 1, please refer to Figure 1-2 The present invention provides a technical solution: a small liquid-solid dual-fuel molten salt reactor core loaded with cross-spiral fuel, which includes a core active area 1, a control drum 2 and a reflector 3 in this embodiment. The core active area 1 has a side distance of 27.5 cm and a height of 43.2 cm. There are 6 control drums 2. The main material of the control drum 2 is beryllium oxide. A neutron absorbing material is provided within a range of 120° on one side. The neutron absorbing material is boron carbide with a boron 10 enrichment of 100%. The control drum 2 can realize the control of the core by adjusting the relative position of the neutron absorbing material and the active area through rotation. The core active area 1 and the control drum 2 are both embedded in the reflector 3, and the maximum thickness of the reflector is 13.4 cm.

[0024] Example 2, please refer to Figure 1 The active area 1 includes fuel elements 1-1, fluoride salt coolant 1-2 and cladding 1-3 encapsulating the active area. The fuel elements 1-1 are arranged in a regular hexagon in the core active area 1. There are 61 fuel elements in the core active area 1. The area between two adjacent fuel elements 1-1 is a channel for the fluoride salt coolant 1-2. The material used for the fluoride salt coolant 1-2 is 7LiF-KF-UF4 (49.55-49.55-0.9mol), in which the enrichment of U-235 in UF4 is 30wt.%; the material used for the cladding 1-3 of the active area is Zr-4.

[0025] Example 3, please refer to Figure 2-3 The fuel element 1-1 adopts a cross spiral type. The specific size of the fuel element is shown in Figure 3, a hexagonal arrangement is adopted in the core active area 1, and the blades of adjacent fuel elements 1-1 will touch each time they rotate 30 degrees, which means that every two adjacent fuel elements 1-1 have 5 fixed points; a fuel element 1-1 includes an axial reflection layer 1-1-1, a He gas cavity 1-1-2, a solid fuel 1-1-3, a spectral shift absorber 1-1-4 and a fuel cladding covering the fuel element.

[0026] The material used for the axial reflection layer 1-1-1 in the fuel element 1-1 is beryllium oxide, the thickness of the upper axial reflection layer is 6 cm, the thickness of the lower reflection layer is 7 cm, the material filled in the He gas cavity 1-1-2 is helium, the height is 5 cm, the material used for the solid fuel 1-1-3 is solid uranium carbide, wherein the U-235 enrichment is 45.684wt.%, the height is 25 cm, the material used for the spectral shift absorber 1-1-4 is Re, the height is 0.1 cm, and the material used for the fuel cladding 1-1-5 is Zr-4.

[0027] The core thermal power is set to 1000kW, the core operating temperature is 1000K, the coolant flow rate is 1m / s, and the inlet temperature is set to 873K. According to the reactor neutronics calculation and three-dimensional thermal hydraulic calculation, the present invention has almost no difference in neutronics compared with the reactor of rod-type fuel elements. In terms of thermal hydraulics, the maximum flow rate of the coolant in the cross-spiral fuel is increased by about 13% compared with the maximum flow rate in the rod-type fuel, and the flow rate changes periodically. At the same time, the maximum temperature of the cross-spiral fuel is reduced by about 9.1% compared with the traditional rod-shaped fuel. Compared with the traditional design, the present invention can effectively reduce the temperature of the fuel core block and improve the heat transfer performance of the reactor.

[0028] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A small liquid-solid dual-fuel molten salt reactor core loaded with cross-helical fuel, characterized in that: It includes a core active area (1), a control drum (2) and a reflector (3); The active region (1) comprises fuel elements (1-1), a fluoride salt coolant (1-2) and a cladding (1-3) encapsulating the active region. The fuel elements (1-1) are arranged in a regular hexagon in the core active region (1). There are 61 fuel elements in the core active region (1). The area between two adjacent fuel elements (1-1) is a channel for the fluoride salt coolant (1-2).

2. A small liquid-solid dual-fuel molten salt reactor core loaded with cross-helical fuel according to claim 1, characterized in that: The material used for the fluoride salt coolant (1-2) is 7LiF-KF-UF4 (49.55-49.55-0.9 mol), wherein the enrichment of U-235 in UF4 is 30 wt.%; the material used for the cladding (1-3) of the active zone is Zr-4.

3. A small liquid-solid dual-fuel molten salt reactor core loaded with cross-helical fuel according to claim 1, characterized in that: The fuel elements (1-1) are of a cross-spiral type and are arranged in a hexagonal pattern in the core active area (1). The blades of adjacent fuel elements (1-1) touch each other every 30 degrees of rotation, which means that every two adjacent fuel elements (1-1) have five fixed points. A fuel element (1-1) includes an axial reflection layer (1-1-1), a He gas cavity (1-1-2), solid fuel (1-1-3), a spectral shift absorber (1-1-4), and a fuel cladding (1-1-5) covering the fuel element.

4. The small liquid-solid dual-fuel molten salt reactor core loaded with cross-helical fuel according to claim 1 is characterized in that: The material used for the axial reflection layer (1-1-1) in the fuel element (1-1) is beryllium oxide, the material filled in the He gas cavity (1-1-2) is helium, the material used for the solid fuel (1-1-3) is solid uranium carbide, wherein the U-235 enrichment is 45.684wt.%, the material used for the spectral shift absorber (1-1-4) is Re, and the material used for the fuel cladding (1-1-5) is Zr-4.

5. The small liquid-solid dual-fuel molten salt reactor core loaded with cross-helical fuel according to claim 1 is characterized in that: The control drum (2) is embedded in the reflective layer (3). There are a total of six control drums (2) evenly distributed around the periphery of the core active area (1). The control drums are rotatable.

6. The small liquid-solid dual-fuel molten salt reactor core loaded with cross-helical fuel according to claim 1 is characterized by: The main material of the control drum (2) is beryllium oxide, and a neutron absorbing material is arranged within a range of 120 degrees on one side, wherein the neutron absorbing material is boron carbide with a boron 10 enrichment of 100%.

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