SiC-clad fuel element, nuclear reactor, and method for manufacturing SiC-clad fuel element
By setting up a containment cavity inside the SiC cladding, filling it with particulate or liquid molten salt fuel, and sealing it with a sealing plug, the problem of SiC cladding fuel element rupture caused by hard contact was solved, achieving stable operation of the nuclear reactor and improving neutron economy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA NUCLEAR POWER TECH RES INST CO LTD
- Filing Date
- 2025-12-29
- Publication Date
- 2026-04-21
AI Technical Summary
SiC-clad fuel elements are prone to breakage and failure due to the mechanical interaction between the pellet and the cladding, a problem that is difficult to solve effectively with existing technologies.
A cavity is set inside the SiC cladding, filled with particulate or liquid molten salt fuel, and sealed with a sealing plug to ensure soft contact between the molten salt fuel and the SiC cladding, avoiding hard contact and mechanical interaction.
This effectively avoids the risk of SiC cladding failure, improves neutron economy, and ensures the normal operation of the nuclear reactor and the safety of the production workshop.
Smart Images
Figure CN121905591A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of nuclear fuel technology, and in particular to a SiC clad fuel element, a nuclear reactor, and a method for manufacturing the SiC clad fuel element. Background Technology
[0002] Silicon carbide (SiC) is considered one of the main candidates for high-performance fuel cladding materials due to its high temperature resistance, radiation resistance, good compatibility with various coolants, and good neutron economy. Currently, the common design for SiC-clad fuel elements involves directly loading solid or hollow cylindrical fuel pellets into a SiC cladding tube, and then sealing both ends with SiC ceramic end plugs.
[0003] These solid fuel pellets undergo thermal expansion and radiation swelling during operation in the reactor, and may even break into several pieces during their service life due to operation, potentially leading to hard contact between the fuel pellets and the SiC cladding. However, due to the intrinsic brittleness of SiC, the strain that the SiC cladding can withstand is relatively limited (0.1% strain can lead to the formation of microcracks). When hard contact occurs between the fuel pellets and the SiC cladding, the SiC cladding fuel element is prone to failure due to the mechanical interaction between the pellet and the cladding, causing the SiC cladding to fracture. Summary of the Invention
[0004] The main objective of this application is to propose a SiC clad fuel element, a nuclear reactor, and a method for manufacturing SiC clad fuel elements, aiming to solve the technical problem that SiC clad fuel elements are prone to failure due to mechanical interaction between the fuel pellet and the cladding.
[0005] To achieve the above objectives, in a first aspect, this application proposes a SiC-clad fuel element, comprising: The SiC cladding shell has a receiving cavity. The SiC cladding shell has a first end and a second end that are disposed opposite to each other. The first end has a first opening and the second end has a second opening. Both the first opening and the second opening are in communication with the receiving cavity. A sealing assembly, the sealing assembly including a first sealing plug and a second sealing plug, the first sealing plug blocking the first opening and the second sealing plug blocking the second opening; Molten salt fuel, which is disposed within the containment cavity, and has an initial state of being granular or liquid.
[0006] In some embodiments, the molten salt fuel is in granular form when it is in the initial state, and the diameter D of the molten salt fuel satisfies: 0.01mm ≤ D ≤ 0.5mm.
[0007] In some embodiments, the molten salt fuel is in granular form when in the initial state, and the molten salt fuel also has a liquid service state, wherein the melting point T1 of the molten salt fuel satisfies: T1≤500℃.
[0008] In some embodiments, when the molten salt fuel is in the initial state, the volume of the molten salt fuel is smaller than the volume of the receiving cavity.
[0009] In some embodiments, the receiving cavity is provided with an air chamber, and the air chamber is in a vacuum state; Alternatively, the gas cavity may be filled with helium at one atmosphere.
[0010] In some embodiments, the SiC cladding includes at least a first structural layer and a second structural layer, wherein the first structural layer is disposed inside the second structural layer, the first structural layer is made of silicon carbide ceramic matrix composite material, and the second structural layer is made of silicon carbide ceramic. Alternatively, the SiC cladding may include at least a first structural layer, a second structural layer, and a third structural layer, wherein the first structural layer is disposed inside the second structural layer, the second structural layer is disposed inside the third structural layer, both the first and third structural layers are made of silicon carbide ceramic, and the second structural layer is made of silicon carbide ceramic matrix composite material.
[0011] In some embodiments, both the first sealing plug and the second sealing plug are made of silicon carbide ceramic.
[0012] In some embodiments, a first connecting gap is provided between the first sealing plug and the first opening, the first connecting gap being filled with a connecting material, the connecting material being configured to form a dense sealing structure within the first connecting gap when heated; Furthermore, a second connecting gap is provided between the second sealing plug and the second opening, the second connecting gap being filled with the connecting material, the connecting material being configured to form a dense sealing structure within the second connecting gap upon heating.
[0013] In some embodiments, the molten salt fuel is made from LiF and UF4 in a molar ratio of 72:28; Alternatively, the molten salt fuel is made from NaF, LiF and UF4 in a molar ratio of 60:21:19; Alternatively, the molten salt fuel is made from NaF, LiF and UF4 in a molar ratio of 35:37:28; Alternatively, the molten salt fuel is made from NaF, LiF and UF4 in a molar ratio of 24.3:43.5:32.2; Alternatively, the molten salt fuel is made from NaF, LiF, KF and UF4 in a molar ratio of 11.2:45.3:41.0:2.5; Alternatively, the molten salt fuel is made from NaF, LiF, ZrF4 and UF4 in a molar ratio of 32.0:35.0:29.0:4.0; Alternatively, the molten salt fuel is made from RbF, ZrF4 and UF4 in a molar ratio of 48.0:48.0:4.0; Alternatively, the molten salt fuel is made from LiF, BeF2, ThF4 and UF4 in a molar ratio of 68:20:11:7:0.3; Alternatively, the molten salt fuel is made from LiF, NaF, BeF2, ThF4 and UF4 in a molar ratio of 41.8:31.1:4.6:19.95:2.55.
[0014] Secondly, this application proposes a nuclear reactor, comprising: SiC-clad fuel element as described in any of the above embodiments; A cooling assembly filled with a coolant for cooling the SiC-clad fuel element; The operating temperature T2 of the coolant satisfies: T2≥500℃.
[0015] In some embodiments, the coolant is made of LiF and BeF2 in a molar ratio of 66:34; Alternatively, the coolant is made from NaF and BeF2 in a molar ratio of 57:43; Alternatively, the coolant is made of LiF and RbF in a molar ratio of 44:56; Alternatively, the coolant is made of LiF, NaF and KF in a molar ratio of 46.5:11.5:42; Alternatively, the coolant is made of LiF, NaF and RbF in a molar ratio of 42:6:52; Alternatively, the coolant is made of LiF, NaF and BeF2 in a molar ratio of 31:31:38; Alternatively, the coolant is made from RbF and ZrF4 in a molar ratio of 58:42; Alternatively, the coolant is made of LiF, NaF and ZrF4 in a molar ratio of 26:37:37; Alternatively, the coolant is made of LiCl and KCl in a molar ratio of 59.45:40.5; Alternatively, the coolant is made of LiCl and RbCl in a molar ratio of 58:42; Alternatively, the coolant is made of KCl and MgCl2 in a molar ratio of 68:32; Alternatively, the coolant is made of NaCl and MgCl2 in a molar ratio of 68:32; Alternatively, the coolant is made of NaCl, KCl and MgCl2 in a molar ratio of 33:18:49; Alternatively, the coolant may be made of helium. Alternatively, the coolant may be made of lead or lead-bismuth; Alternatively, the coolant may be made of sodium.
[0016] Thirdly, this application proposes a method for manufacturing a SiC-clad fuel element, used to manufacture the SiC-clad fuel element in any of the above embodiments; comprising the following steps: The first opening is sealed using the first sealing plug; The molten salt fuel, ground and crushed into granules, is placed inside the receiving cavity; The second opening is sealed using the second sealing plug.
[0017] Compared with the prior art, the beneficial effects of this application are: In the technical solution of this application, during the service of molten salt fuel, the molten salt fuel releases heat, thereby heating the nuclear reactor through the SiC cladding fuel elements. At this time, the granular molten salt fuel melts into a liquid form, or the liquid molten salt fuel remains in a liquid form. By using the granular or liquid molten salt fuel provided in this application, it is ensured that the molten salt fuel and the inner wall of the SiC cladding are always in soft contact, that is, there is no hard contact or contact sharp corner between the molten salt fuel and the inner wall of the SiC cladding. During service, the molten salt fuel will not cause impact and extrusion stress on the SiC cladding, thereby avoiding the hard contact between the traditional solid fuel pellets and the SiC cladding. This avoids the risk of SiC cladding failure due to the mechanical interaction (PCMI) between the fuel pellets and the SiC cladding.
[0018] Furthermore, compared with traditional solid pellet fuel elements, the SiC-clad molten salt fuel element provided in this application does not require springs for solid pellet compression in its components, which reduces the absorption of neutrons by the spring material and has certain benefits for improving the neutron economy of the SiC-clad fuel element.
[0019] Nuclear reactors using SiC-clad fuel elements can ensure normal operation of the nuclear reactor.
[0020] The manufacturing method for the above-mentioned SiC-clad fuel element is simple and easy to implement, and can improve the yield of SiC-clad fuel element. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.
[0022] Figure 1 This is a schematic diagram of the structure of a SiC-clad fuel element provided in an embodiment of this application; Figure 2 A method for manufacturing a SiC-clad fuel element is provided in one embodiment of this application.
[0023] Explanation of icon numbers: 10. Fuel elements; 100. SiC cladding; 110. First end; 120. Second end; 130. Receiving cavity; 111. The first opening; 121. The second opening; 131. Air cavity; 1111, First inclined sidewall; 200. Sealing assembly; 210. First sealing plug; 220. Second sealing plug; 211. Second inclined sidewall; 300. Molten salt fuel.
[0024] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0026] It should be noted that if the embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.
[0027] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or," "and / or," or "and / or" throughout the text implies three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where A and B are simultaneously satisfied. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.
[0028] Silicon carbide (SiC) is considered one of the main candidates for high-performance fuel cladding materials due to its high temperature resistance, radiation resistance, good compatibility with various coolants, and good neutron economy. Currently, the common design for SiC-clad fuel elements involves directly loading solid or hollow cylindrical fuel pellets into a SiC cladding tube, and then sealing both ends with SiC ceramic end plugs.
[0029] These solid fuel pellets undergo thermal expansion and radiation swelling during operation in the reactor, and may even break into several pieces during their service life due to operation, potentially leading to hard contact between the fuel pellets and the SiC cladding. However, due to the intrinsic brittleness of SiC, the strain that the SiC cladding can withstand is relatively limited (0.1% strain can lead to the formation of microcracks). When hard contact occurs between the fuel pellets and the SiC cladding, the SiC cladding fuel element is prone to failure due to the mechanical interaction between the pellet and the cladding, causing the SiC cladding to fracture.
[0030] Based on this, in order to solve the above-mentioned technical problems, refer to Figure 1 This application provides an embodiment of a SiC-clad fuel element 10, including a SiC cladding 100, a sealing assembly 200, and molten salt fuel 300. The SiC cladding 100 has a receiving cavity 130 and two opposing end portions 110 and 120. The first end portion 110 has a first opening 111, and the second end portion 120 has a second opening 121. Both the first opening 111 and the second opening 121 communicate with the receiving cavity 130. The sealing assembly 200 includes a first sealing plug 210 and a second sealing plug 220. The first sealing plug 210 blocks the first opening 111, and the second sealing plug 220 blocks the second opening 121. The molten salt fuel 300 is disposed within the receiving cavity 130 and has an initial state that is either particulate or liquid.
[0031] Specifically, in this embodiment, due to the inherent brittleness of SiC material, the SiC cladding 100 is designed as a straight tubular structure to avoid curved surfaces, thus facilitating the processing and shaping of the SiC cladding 100. When assembling the SiC-clad fuel element 10, the first opening 111 is first sealed with a first sealing plug 210, leaving the SiC cladding 100 open at only one end. Then, molten salt fuel 300, either ground into small particles or in liquid form, is loaded into the SiC cladding 100, placing the molten salt fuel 300 within the receiving cavity 130. Finally, the second opening 121 is sealed with a second sealing plug 220, sealing both ends of the SiC cladding 100 and thus sealing the molten salt fuel 300 within the receiving cavity 130.
[0032] During the service of molten salt fuel 300, molten salt fuel 300 will release heat to heat the nuclear reactor through SiC clad fuel element 10. At this time, the granular molten salt fuel 300 will melt into liquid form, or the liquid molten salt fuel 300 will remain in liquid form. By using the granular or liquid molten salt fuel 300 provided in this application, it is ensured that the molten salt fuel 300 and the inner wall of the SiC cladding 100 are always in soft contact, that is, there are no sharp contact corners between the molten salt fuel 300 and the inner wall of the SiC cladding 100. In this way, when the molten salt fuel 300 undergoes thermal expansion or irradiation swelling during service, it will not cause impact and extrusion stress on the SiC cladding 100, thereby avoiding the hard contact between the traditional solid fuel pellet and the SiC cladding 100, and avoiding the risk of SiC cladding 100 cracking and failing due to the mechanical interaction (PCMI) between the pellet and the SiC cladding 100.
[0033] Furthermore, compared with the traditional solid pellet fuel element 10, the SiC clad molten salt fuel 300 element 10 provided in this application does not require a spring for pressing the solid pellets, which reduces the absorption of neutrons by the spring material and has certain benefits for improving the neutron economy of the SiC clad fuel element 10.
[0034] In some embodiments, the molten salt fuel 300 is granular in its initial state, and the diameter D of the molten salt fuel 300 satisfies: 0.01mm ≤ D ≤ 0.5mm. For example, the value of D can be 0.01mm, 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.13mm, 0.15mm, 0.18mm, 0.2mm, 0.23mm, 0.25mm, 0.27mm, 0.29mm, 0.3mm, 0.32mm, 0.34mm, 0.36mm, 0.38mm, 0.4mm, 0.42mm, 0.44mm, 0.46mm, 0.48mm, 0.5mm, etc.
[0035] Specifically, in this embodiment, a mechanical hammer or similar structure can be used to apply mechanical force to the solid molten salt fuel 300, causing it to be ground and broken into small particles with a particle size range of 0.01mm-0.5mm. Setting the particle size of the molten salt fuel 300 within this range effectively reduces its volume, lowers the impact stress between the molten salt fuel 300 and the SiC cladding 100 during service, and prevents hard contact between them, thereby improving the structural stability of the SiC cladding 100 and preventing cracking. Furthermore, when the molten salt fuel 300 is loaded into the receiving cavity 130 of the SiC cladding 100, excessive dust is prevented from being stirred up, thus ensuring cleanliness during the production of the SiC clad fuel element 10 and improving the safety of the production workshop.
[0036] In some embodiments, the molten salt fuel 300 is in a particulate form in its initial state, and the molten salt fuel 300 also has a liquid service state. The melting point T1 of the molten salt fuel 300 satisfies: T1 ≤ 500°C. For example, the value of T1 can be 500°C, 490°C, 480°C, 475°C, 450°C, 445°C, 425°C, etc.
[0037] Specifically, in this embodiment, the molten salt fuel 300 can be selected from materials with low melting point, high boiling point, high thermal conductivity, good neutron economy, and stable chemical properties. Furthermore, the melting point of the molten salt fuel 300 generally does not exceed 500°C to meet the heating requirements of the nuclear reactor.
[0038] In some embodiments, refer to Figure 1When the molten salt fuel 300 is in its initial state, its volume is smaller than the volume of the receiving cavity 130. In other words, in the initial state, the receiving cavity 130 is not completely filled with the molten salt fuel 300, ensuring that a certain amount of space is reserved within the receiving cavity 130. For example, the receiving cavity 130 may have a gas cavity 131, which is in a vacuum state. Alternatively, the gas cavity 131 may be filled with helium gas at one atmosphere.
[0039] Specifically, in this embodiment, during service, the molten salt fuel 300 will generate fission gas, so the containment cavity 130 has a gas cavity 131 for containing the fission gas, so as to provide a place to contain the fission gas generated during service.
[0040] It should be noted that, since this application uses molten salt fuel 300 in particulate form or molten salt fuel 300 in liquid form, the molten salt fuel 300 of this application is expected to generate more fission gas during service compared to traditional solid fuel pellets. Therefore, the containment cavity 130 of this application needs to be provided with a larger volume gas cavity 131 or filled with less helium in the initial state to ensure that the containment cavity 130 can more effectively contain the fission gas.
[0041] Furthermore, the SiC cladding 100 exhibits an extremely low creep rate and can withstand relatively high compressive stress. Therefore, the helium filling can be performed at a relatively low pressure to accommodate more fission gases generated during reactor operation. Consequently, this embodiment employs atmospheric pressure (1 atmosphere) for helium filling, or a vacuum method can be used directly.
[0042] In some embodiments, the SiC cladding 100 includes at least a first structural layer and a second structural layer, the first structural layer being disposed inside the second structural layer, the first structural layer being made of silicon carbide ceramic matrix composite material, and the second structural layer being made of silicon carbide ceramic.
[0043] Specifically, in this embodiment, pure SiC ceramics may experience catastrophic brittle fracture. Therefore, the SiC cladding 100 is often designed as a SiC fiber-reinforced SiC ceramic matrix composite material with pseudoplastic characteristics. For example, in the production of the SiC cladding 100, a SiC fiber-reinforced SiC ceramic matrix composite material can be used as the base layer, and then a dense SiC ceramic layer can be formed on the SiC ceramic matrix composite material layer using chemical vapor deposition (CVD). This improves the structural strength and structural stability of the SiC cladding 100.
[0044] Alternatively, in other embodiments, the SiC shell 100 includes at least a first structural layer, a second structural layer, and a third structural layer, with the first structural layer disposed inside the second structural layer, the second structural layer disposed inside the third structural layer, both the first and third structural layers being made of silicon carbide ceramic, and the second structural layer being made of silicon carbide ceramic matrix composite material.
[0045] Specifically, in this embodiment, when producing the SiC cladding 100, in addition to forming a dense SiC ceramic layer on the outside of the SiC ceramic matrix composite layer using chemical vapor deposition (CVD), a dense SiC ceramic layer can also be formed on both the inner and outer sides of the SiC ceramic matrix composite layer, so that the SiC cladding 100 forms a three-layer "sandwich" structure, thereby further improving the structural strength and structural stability of the SiC cladding 100.
[0046] In some embodiments, both the first sealing plug 210 and the second sealing plug 220 are made of silicon carbide ceramic.
[0047] Specifically, in this embodiment, both the first sealing plug 210 and the second sealing plug 220 can be high-density SiC ceramic blocks prepared by chemical vapor deposition (CVD). Using the above materials can, on the one hand, ensure the structural stability and structural strength of the first sealing plug 210 and the second sealing plug 220; on the other hand, it can ensure good material compatibility between the first sealing plug 210, the second sealing plug 220 and the SiC shell 100, thereby improving the connection stability between the first sealing plug 210, the second sealing plug 220 and the SiC shell 100, and preventing harmful interactions between the first sealing plug 210, the second sealing plug 220 and the SiC shell 100.
[0048] In some embodiments, refer to Figure 1 A first connecting gap is formed between the first sealing plug 210 and the first opening 111, and the first connecting gap is filled with a connecting material configured to form a dense sealing structure within the first connecting gap upon heating. Similarly, a second connecting gap is formed between the second sealing plug 220 and the second opening 121, and the second connecting gap is filled with a connecting material configured to form a dense sealing structure within the second connecting gap upon heating.
[0049] Specifically, in this embodiment, by filling the first connection gap with connecting material, the first connection gap can be eliminated, thereby improving the sealing effect between the first sealing plug 210 and the first opening 111. Similarly, by filling the second connection gap with connecting material, the second connection gap can be eliminated, thereby improving the sealing effect between the second sealing plug 220 and the second opening 121, thus ensuring the airtightness of the receiving cavity 130.
[0050] Taking the filling of the first connecting gap with connecting material as an example, firstly, a connecting material slurry is prepared. For example, the connecting material and dispersant can be added to an organic solvent and ultrasonically dispersed to form a connecting slurry. The connecting material includes at least one of ceramic powder, glass powder, metal powder, and precursor. Then, the connecting material slurry is uniformly coated into the first connecting gap. Then, under a protective atmosphere, the connecting material slurry is heated (for example, heated to 100℃~300℃) and kept at that temperature for 0.1h-4h for curing, so that the connecting material slurry is cured to form a connecting layer. Finally, the cured connecting layer is heat-treated to densify the connecting layer, so that the first sealing plug 210 is densely connected to the SiC shell 100 to form a sealed SiC shell 100.
[0051] The steps for filling the second connection gap with connecting material are the same as those in the above embodiment, and will not be repeated here.
[0052] In some embodiments, refer to Figure 1 The SiC shell 100 has a first inclined sidewall 1111 at the first opening 111, and the first inclined sidewall 1111 extends outward from one end near the receiving cavity 130 to the end away from the receiving cavity 130; the first sealing plug 210 has a second inclined sidewall 211, and the second inclined sidewall 211 and the first inclined sidewall 1111 cooperate with each other.
[0053] Specifically, in this embodiment, the cooperation between the first inclined sidewall 1111 and the second inclined sidewall 211 can, on the one hand, provide guidance for the first sealing plug 210 to be inserted into the first opening 111, thereby improving the alignment accuracy between the first sealing plug 210 and the first opening 111; on the other hand, it facilitates the flow of the connecting material in the first connecting gap, improves the uniformity of the flow of the connecting material in the first connecting gap, and enhances the sealing effect at the first connecting gap.
[0054] The mating structure of the second sealing plug 220 and the second opening 121 is the same as the mating structure of the first sealing plug 210 and the first opening 111 in the above embodiment, and will not be described again here.
[0055] In some embodiments, referring to Table 1, molten salt fuel 300 is made from LiF and UF4 in a molar ratio of 72:28. Alternatively, molten salt fuel 300 is made from NaF, LiF, and UF4 in a molar ratio of 60:21:19. Alternatively, molten salt fuel 300 is made from NaF, LiF, and UF4 in a molar ratio of 35:37:28. Alternatively, molten salt fuel 300 is made from NaF, LiF, and UF4 in a molar ratio of 24.3:43.5:32.2. Alternatively, molten salt fuel 300 is made from NaF, LiF, KF, and UF4 in a molar ratio of 11.2:45.3:41.0:2.5. Alternatively, molten salt fuel 300 is made from NaF, LiF, ZrF4, and UF4 in a molar ratio of 32.0:35.0:29.0:4.0. Alternatively, molten salt fuel 300 is made from RbF, ZrF4, and UF4 in a molar ratio of 48.0:48.0:4.0. Alternatively, molten salt fuel 300 is made from LiF, BeF2, ThF4, and UF4 in a molar ratio of 68:20:11:7:0.3. Alternatively, molten salt fuel 300 is made from LiF, NaF, BeF2, ThF4, and UF4 in a molar ratio of 41.8:31.1:4.6:19.95:2.55.
[0056]
[0057] Table 1 It should be noted that molten salt fuel 300 can also be selected from other fluoride or chloride fuels, and the melting point of molten salt fuel 300 should preferably not exceed 500°C.
[0058] Correspondingly, another embodiment of this application also provides a nuclear reactor, which includes the SiC clad fuel element 10 of any of the above embodiments. The nuclear reactor also includes a cooling assembly filled with coolant, which is used to cool the SiC clad fuel element 10. The operating temperature T2 of the coolant satisfies: T2 ≥ 500℃. For example, the value of T2 can be 500℃, 520℃, 550℃, 570℃, 590℃, 600℃, 650℃, 700℃, 750℃, 800℃, etc.
[0059] Specifically, in this embodiment, by using the SiC clad fuel element 10 provided in the above embodiments, in conjunction with a coolant, the normal operation of the nuclear reactor can be guaranteed.
[0060] In some embodiments, referring to Table 2, the coolant is prepared from LiF and BeF2 in a molar ratio of 66:34. Alternatively, the coolant is prepared from NaF and BeF2 in a molar ratio of 57:43. Alternatively, the coolant is prepared from LiF and RbF in a molar ratio of 44:56. Alternatively, the coolant is prepared from LiF, NaF, and KF in a molar ratio of 46.5:11.5:42. Alternatively, the coolant is prepared from LiF, NaF, and RbF in a molar ratio of 42:6:52. Alternatively, the coolant is prepared from LiF, NaF, and BeF2 in a molar ratio of 31:31:38. Alternatively, the coolant is prepared from RbF and ZrF4 in a molar ratio of 58:42. Alternatively, the coolant is prepared from LiF, NaF, and ZrF4 in a molar ratio of 26:37:37. Alternatively, the coolant is prepared from LiCl and KCl in a molar ratio of 59.45:40.5. Alternatively, the coolant may be made from LiCl and RbCl in a molar ratio of 58:42. Alternatively, the coolant may be made from KCl and MgCl₂ in a molar ratio of 68:32. Alternatively, the coolant may be made from NaCl and MgCl₂ in a molar ratio of 68:32. Alternatively, the coolant may be made from NaCl, KCl, and MgCl₂ in a molar ratio of 33:18:49. Alternatively, the coolant may be made from helium. Alternatively, the coolant may be made from lead or lead-bismuth. Alternatively, the coolant may be made from sodium.
[0061]
[0062] Table 2 It should be noted that there are various coolants compatible with SiC cladding 100, and it is not limited to the coolants mentioned above.
[0063] Specifically, in this embodiment, in order to keep the molten salt fuel 300 element 10 of the SiC cladding 100 in a liquid state during service, this application requires that the temperature of the coolant be no lower than 500°C during normal operation. The wall thickness of the SiC cladding 100 is generally about 1 mm. After the SiC cladding 100 is irradiated in the reactor, its thermal conductivity will decrease, and the temperature difference along the wall thickness direction of the SiC cladding 100 can reach about 100°C. A coolant temperature of no lower than 500°C can ensure that the molten salt fuel 300 inside the SiC cladding 100 molten salt fuel 300 element 10 is always in a liquid state.
[0064] Correspondingly, another embodiment of this application also provides a method for manufacturing a SiC-clad fuel element 10, used to manufacture the SiC-clad fuel element 10 in any of the above embodiments; refer to Figure 2 This includes the following steps: Step S100: Seal the first opening 111 using the first sealing plug 210.
[0065] In this step, after the first sealing plug 210 blocks the first opening 111, the SiC shell 100 only has an opening at one end, forming a semi-closed structure.
[0066] Step S200: Place the molten salt fuel 300, which has been ground and crushed into granules, into the receiving cavity 130.
[0067] In this step, since the molten salt fuel 300 is in granular form, it will not cause a large impact on the side wall of the SiC cladding 100 when it is placed into the receiving cavity 130. This ensures the structural stability and strength of the SiC cladding 100 and prevents the SiC cladding 100 from cracking or being damaged.
[0068] Step S300: Seal the second opening 121 using the second sealing plug 220.
[0069] In this step, after an appropriate amount of molten salt fuel 300 is placed into the receiving cavity 130, the second opening 121 is sealed by the second sealing plug 220, so that the receiving cavity 130 is in a completely sealed state.
[0070] Specifically, in this embodiment, the above manufacturing method is simple and easy to operate, which can reduce the manufacturing difficulty of SiC-clad fuel element 10 and improve the yield of SiC-clad fuel element 10.
[0071] Thanks to the improvements to the SiC clad fuel element 10 described above, the nuclear reactor and the manufacturing method of the SiC clad fuel element 10 in this embodiment have the same technical effects as the SiC clad fuel element 10 described above, and will not be repeated here.
[0072] It should be noted that other undisclosed contents of the SiC clad fuel element 10, nuclear reactor and manufacturing method of SiC clad fuel element 10 provided in this application can be found in the prior art, and will not be repeated here.
[0073] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural transformations made based on the content of the specification and drawings of this application under the concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.
Claims
1. A SiC-clad fuel element, characterized in that, include: The SiC cladding shell has a receiving cavity. The SiC cladding shell has a first end and a second end that are disposed opposite to each other. The first end has a first opening and the second end has a second opening. Both the first opening and the second opening are in communication with the receiving cavity. A sealing assembly, the sealing assembly including a first sealing plug and a second sealing plug, the first sealing plug blocking the first opening and the second sealing plug blocking the second opening; Molten salt fuel, wherein the molten salt fuel is disposed within the containment cavity, and the molten salt fuel is initially in a particulate or liquid state.
2. The SiC-clad fuel element according to claim 1, characterized in that, The molten salt fuel is granular in the initial state, and the diameter D of the molten salt fuel satisfies: 0.01mm≤D≤0.5mm.
3. The SiC-clad fuel element according to claim 1, characterized in that, The molten salt fuel is in granular form in the initial state, and the molten salt fuel also has a liquid service state. The melting point T1 of the molten salt fuel satisfies: T1≤500℃.
4. The SiC-clad fuel element according to claim 1, characterized in that, When the molten salt fuel is in the initial state, the volume of the molten salt fuel is smaller than the volume of the accommodating cavity.
5. The SiC-clad fuel element according to claim 1, characterized in that, The receiving cavity is provided with an air chamber, and the air chamber is in a vacuum state; Alternatively, the gas cavity may be filled with helium at one atmosphere.
6. The SiC-clad fuel element according to claim 1, characterized in that, The SiC cladding includes at least a first structural layer and a second structural layer, wherein the first structural layer is disposed inside the second structural layer, the first structural layer is made of silicon carbide ceramic matrix composite material, and the second structural layer is made of silicon carbide ceramic. Alternatively, the SiC cladding may include at least a first structural layer, a second structural layer, and a third structural layer, wherein the first structural layer is disposed inside the second structural layer, the second structural layer is disposed inside the third structural layer, both the first and third structural layers are made of silicon carbide ceramic, and the second structural layer is made of silicon carbide ceramic matrix composite material.
7. The SiC-clad fuel element according to claim 1, characterized in that, Both the first sealing plug and the second sealing plug are made of silicon carbide ceramic.
8. The SiC-clad fuel element according to claim 1, characterized in that, The first sealing plug and the first opening have a first connecting gap, the first connecting gap is filled with a connecting material, and the connecting material is configured to form a dense sealing structure in the first connecting gap when heated; Furthermore, a second connecting gap is provided between the second sealing plug and the second opening, the second connecting gap being filled with the connecting material, the connecting material being configured to form a dense sealing structure within the second connecting gap upon heating.
9. The SiC-clad fuel element according to claim 1, characterized in that, The molten salt fuel is made from LiF and UF4 in a molar ratio of 72:28; Alternatively, the molten salt fuel is made from NaF, LiF and UF4 in a molar ratio of 60:21:19; Alternatively, the molten salt fuel is made from NaF, LiF and UF4 in a molar ratio of 35:37:28; Alternatively, the molten salt fuel is made from NaF, LiF and UF4 in a molar ratio of 24.3:43.5:32.2; Alternatively, the molten salt fuel is made from NaF, LiF, KF and UF4 in a molar ratio of 11.2:45.3:41.0:2.5; Alternatively, the molten salt fuel is made from NaF, LiF, ZrF4 and UF4 in a molar ratio of 32.0:35.0:29.0:4.0; Alternatively, the molten salt fuel is made from RbF, ZrF4 and UF4 in a molar ratio of 48.0:48.0:4.0; Alternatively, the molten salt fuel is made from LiF, BeF2, ThF4 and UF4 in a molar ratio of 68:20:11:7:0.3; Alternatively, the molten salt fuel is made from LiF, NaF, BeF2, ThF4 and UF4 in a molar ratio of 41.8:31.1:4.6:19.95:2.
55.
10. A nuclear reactor, characterized in that, include: The SiC-clad fuel element as claimed in any one of claims 1 to 9; A cooling assembly filled with a coolant for cooling the SiC-clad fuel element; The operating temperature T2 of the coolant satisfies: T2≥500℃.
11. The nuclear reactor according to claim 10, characterized in that, The coolant is made of LiF and BeF2 in a molar ratio of 66:34; Alternatively, the coolant is made from NaF and BeF2 in a molar ratio of 57:43; Alternatively, the coolant is made of LiF and RbF in a molar ratio of 44:56; Alternatively, the coolant is made of LiF, NaF and KF in a molar ratio of 46.5:11.5:42; Alternatively, the coolant is made of LiF, NaF and RbF in a molar ratio of 42:6:52; Alternatively, the coolant is made of LiF, NaF and BeF2 in a molar ratio of 31:31:38; Alternatively, the coolant is made from RbF and ZrF4 in a molar ratio of 58:42; Alternatively, the coolant is made of LiF, NaF and ZrF4 in a molar ratio of 26:37:37; Alternatively, the coolant is made of LiCl and KCl in a molar ratio of 59.45:40.5; Alternatively, the coolant is made of LiCl and RbCl in a molar ratio of 58:42; Alternatively, the coolant is made of KCl and MgCl2 in a molar ratio of 68:32; Alternatively, the coolant is made of NaCl and MgCl2 in a molar ratio of 68:32; Alternatively, the coolant may be made from NaCl, KCl and MgCl2 in a molar ratio of 33:18:
49.
12. A method for manufacturing a SiC-clad fuel element, used to manufacture the SiC-clad fuel element as described in any one of claims 1 to 9; characterized in that, include: The first opening is sealed using the first sealing plug; The molten salt fuel, ground and crushed into granules, is placed inside the receiving cavity; The second opening is sealed using the second sealing plug.