WO2024051678A1 - Burnable poison coating and preparation method therefor, and nuclear fuel element - Google Patents

Burnable poison coating and preparation method therefor, and nuclear fuel element Download PDF

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Publication number
WO2024051678A1
WO2024051678A1 PCT/CN2023/116956 CN2023116956W WO2024051678A1 WO 2024051678 A1 WO2024051678 A1 WO 2024051678A1 CN 2023116956 W CN2023116956 W CN 2023116956W WO 2024051678 A1 WO2024051678 A1 WO 2024051678A1
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WIPO (PCT)
Prior art keywords
coating
nuclear fuel
burnable poison
combustible
poison coating
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PCT/CN2023/116956
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French (fr)
Chinese (zh)
Inventor
陈向阳
尤
卢俊强
张满
张兆泉
李聪
王晓姣
范武刚
韦享雨
Original Assignee
上海核工程研究设计院股份有限公司
中国科学院上海硅酸盐研究所
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Publication of WO2024051678A1 publication Critical patent/WO2024051678A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
    • C23C14/067—Borides
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/34—Sputtering
    • C23C14/35—Sputtering by application of a magnetic field, e.g. magnetron sputtering
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/54—Controlling or regulating the coating process
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
    • G21C3/02—Fuel elements
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
    • G21C3/02—Fuel elements
    • G21C3/04—Constructional details
    • G21C3/16—Details of the construction within the casing
    • G21C3/20—Details of the construction within the casing with coating on fuel or on inside of casing; with non-active interlayer between casing and active material with multiple casings or multiple active layers
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
    • G21C3/42—Selection of substances for use as reactor fuel
    • G21C3/58—Solid reactor fuel Pellets made of fissile material
    • G21C3/62—Ceramic fuel
    • G21C3/623—Oxide fuels
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

Definitions

  • the present invention relates to the technical field of nuclear fuel, specifically a burnable poison coating and its preparation method and nuclear fuel elements.
  • the initial residual reactivity of the core is relatively large, and chemical compensation poisons, combustible poisons or control rods need to be used to control these residual reactivity.
  • combustible poisons For combustible poisons, the main functions are reflected in two aspects: first, to obtain maximum fuel utilization and reduce fuel cycle costs. The ability of combustible poisons to absorb excess neutrons decreases steadily with operation, so that the reactivity bound by combustible poisons can be gradually and finally fully released during the burn-up process; secondly, it can provide good power distribution control capabilities to realize combustible poisons. The best match between consumption and fuel burn-up in terms of rate and spatial relationship.
  • the combustible toxic materials used in pressurized water reactors at home and abroad mainly include boron stainless steel and boron carbide-alumina. , borosilicate glass and zirconium boride coating.
  • burnable poison absorber and nuclear fuel powder are mixed and co-sintered to form a composite fuel pellet containing the burnable poison absorber, such as Gd 2 O 3 or Er 2 O 3 is dispersed in the UO 2 fuel to form a sintered body;
  • concentration of 10 B in the commercial ZrB 2 coating for AP1000 series nuclear power models exceeds 50wt%.
  • Enriched boric acid is used as the raw material for production.
  • Patent CN111573687A discloses a neutron absorber material with high boron loading and higher neutron reactivity value.
  • the neutron absorber material is a multi-B compound.
  • the chemical formula of the multi-B compound is MB x , where x is not less than 6,
  • the mass fraction of B is not less than 75%
  • M is Al, Mg, Si, Y elements whose thermal neutron absorption cross-section does not exceed 1.5 nm and their mixtures.
  • the patent does not apply the above materials to the surface of nuclear fuel pellets, nor does it verify whether the coating process on the surface of nuclear fuel pellets can be realized.
  • this application provides a burnable poison coating and its preparation method and nuclear fuel elements, which achieve long-term reactivity control and moderator negative temperature while achieving a reactivity adjustment function similar to that of the ZrB coating. Coefficient control can reduce the enrichment of 10 B or even use naturally abundant boric acid for production, reducing material costs.
  • the first aspect of this application provides a burnable poison coating.
  • the burnable poison coating is made of at least one of CeB 6 , SiB 6 , and YB 6 .
  • the relative density of the burnable poison coating is 70% of the theoretical density of the material used. ⁇ 97%.
  • the thickness of the burnable poison coating is between 5 and 20 ⁇ m.
  • the linear density of 10 B in the combustible poison coating is between 0.02 and 0.1 mg/mm.
  • the concentration of 10 B in the burnable poison coating is between 18.4wt% and 30wt%.
  • the initial reactivity value of the burnable poison coating does not differ by more than 200 pcm from a ZrB coating of the same 10 B linear density;
  • the reactivity penalty at the end of life does not differ by more than 30pcm from a ZrB 2 coating with the same 10 B linear density;
  • the mass loss after passing the tape peeling test is less than 0.0006g.
  • the combustible poison coating is prepared by a magnetron sputtering process.
  • the specific operation process includes: using at least one of CeB 6 , SiB 6 , and YB 6 Coating material, fuel pellet is placed in the center of the rotating sample holder bottom plate in the sample chamber, and the upper and lower surfaces of the sample are covered with metal sheets; adjust the Ar gas flow rate in the sample chamber to 60 ⁇ 80 sccm, the vacuum degree to 0.6 ⁇ 0.8Pa, and the temperature to maintain at 200 ⁇ 300°C, after the magnetron arcs, the current to the coating material is maintained at 120 ⁇ 150mA to coat the fuel pellet. After coating for 60 ⁇ 70 hours, the temperature of the sample chamber rises to 400 ⁇ 420°C, and the temperature is maintained for 1 ⁇ 1.2 h.
  • This application also provides a nuclear fuel element, including nuclear fuel pellets, the surface of which is coated with any of the above burnable toxic coatings.
  • the nuclear fuel pellets are made of uranium dioxide, thorium dioxide, plutonium dioxide, uranium dioxide-gadolinium trioxide, thorium dioxide-gadolinium trioxide, plutonium dioxide-gadolinium trioxide, and at least one of its mixtures.
  • it also includes a structural material (cladding material) that isolates the nuclear fuel pellet from the coolant and a sealing material (end plug material) used to block the opening of the structural material; the thermal neutrons of the structural material and sealing material
  • a structural material cladding material
  • a sealing material end plug material
  • the microscopic absorption cross section does not exceed 1.5 nm, and no obvious chemical reaction occurs with the nuclear fuel pellets and coolant between room temperature and 800°C.
  • the present invention provides a burnable poison coating coated on the surface of nuclear fuel pellets: the burnable poison coating is composed of at least one of CeB 6 , SiB 6 and YB 6 . CeB 6 , SiB 6 and The B densities of the three YB 6 materials are 1.52g/cm 3 , 1.7g/cm 3 and 1.56g/cm 3 respectively, which are 30%, 45% and 33% higher than ZrB 2 (1.17g/cm 3 ) respectively. When the 10 B linear density, relative density and thickness of the coating are close, the need for 10 B enrichment can be significantly reduced.
  • the price of boric acid used to prepare B-containing materials increases exponentially with 10 B enrichment, so the use of the burnable poison coating of the present invention can significantly reduce raw material costs.
  • the bonding force between the coating and the matrix core block is also better than that of ZrB 2 , which has higher reliability during service and is more conducive to the safety of the reactor core.
  • the coating of the present invention has good compatibility with the nuclear fuel pellet matrix at room temperature to 800°C, and no interface reaction between the coating and the fuel pellet is observed through a metallographic microscope.
  • Figure 1 is a schematic diagram of a fuel element having fuel pellets covered with a burnable poison coating of the present invention.
  • FIG. 2 is an enlarged cross-sectional view along the direction A-A in FIG. 1 .
  • Figure 3 shows the core characteristic curves (burnup curves) of four combustible poison coatings of SiB 6 , YB 6 , CeB 6 and ZrB 2 with the same 10 B linear density, with ZrB 2 as a comparison.
  • the relationship between the reactivity value curves of the three schemes SiB 6 , YB 6 , and CeB 6 as a function of fuel consumption is basically the same as that of the ZrB 2 curve, so they overlap in the figure.
  • the initial reactivity value does not differ from that of a ZrB 2 coating with the same 10 B linear density by no more than 200 pcm, and the reactivity penalty at the end of its life does not differ from that of a ZrB 2 coating that has the same 10 B linear density by no more than 30 pcm.
  • Figure 4 is a cross-sectional microstructure photo of a UO 2 core block coated with CeB 6 coating on the surface. The thickness of three coatings is measured and marked in each picture. The average coating thickness is approximately 10 ⁇ m.
  • Figure 5 shows the surface grazing incidence X-ray diffraction spectrum of UO 2 core blocks coated with CeB 6 coating. Except for the diffraction peaks of UO 2 matrix, the rest are the diffraction peaks of CeB 6 .
  • Figure 6 shows the tape peeling test results of UO 2 core blocks coated with CeB 6 coating and UO 2 core blocks coated with ZrB 2 coating after five times of 600°C thermal shock test.
  • FIG. 1 is a schematic illustration of a fuel element having fuel pellets covered with a burnable poison coating of the present invention.
  • FIG. 2 is an enlarged cross-sectional view along the direction A-A in FIG. 1 .
  • the upper end plug 1 is used to seal the upper end of the cladding tube; the spring 2 is used to buffer the stress; the cladding 3 is used to seal the fuel pellets to prevent the leakage of fission gas from the nuclear fuel pellets; and apply a coating
  • the pellet 4 is used to provide a controllable chain neutron reaction; the support block 5 and the support tube 6 are used to increase the distance between the fuel pellet and the lower core plate, increase the volume of the fuel rod gas chamber, and reduce the lower core plate.
  • the plate is damaged by irradiation and reduces the internal pressure of the fuel rod in the later stage of irradiation; the lower end plug 7 is used to seal the lower end of the cladding tube; the nuclear fuel pellet 8 provides the matrix pellet for coating; the combustible poison coating 9 is used to coat the fuel core
  • the surface of the block regulates neutron reactivity; the gap 10 between the coating pellet and the cladding tube provides space for the radiation swelling of the fuel pellet and the release of fission gas.
  • the main components of the combustible poison coating 9 include B and at least one of the three elements Ce, Si and Y.
  • the coating can flatten the neutron fluence distribution in the core and achieve long-term reactivity control and moderator negative temperature coefficient control.
  • the coating and substrate have good performance at room temperature to 800°C. Good compatibility.
  • the relative density of the coating is between 70% and 97% (the density of the combustible poison coating is 70% to 97% of the theoretical density of the material used).
  • the coating thickness is between 1.5 ⁇ 20 ⁇ m.
  • the linear density of 10 B in the coating is between 0.02 and 0.1 mg/mm.
  • Example 1 Relationship between coating relative density, 10 B enrichment and coating thickness under different coating linear densities
  • the coating thickness is shown in Table 1 .
  • the coating thickness is between 1.7 ⁇ m and 4.0 ⁇ m. between.
  • Table 1 The relationship between the relative density of combustible poison coatings, 10 B enrichment and coating thickness ( 10 B linear density is 0.02mg/mm)
  • the coating thickness is shown in Table 2 .
  • the coating thickness is between 8.6 ⁇ m and 20 ⁇ m. .
  • Table 2 The relationship between the relative density of combustible toxic coatings, 10 B enrichment and coating thickness ( 10 B linear density is 0.10mg/mm)
  • the linear density of coating 10 B in the combustible poison coating is 0.077mg/mm, which is composed of SiB 6 and YB 6 respectively.
  • CeB 6 when the relative density of the coating is 70% and 97%, the coating thickness is shown in Table 3.
  • the coating thickness is between 6.6 ⁇ m and 15.4 ⁇ m. between.
  • Table 3 The relationship between the relative density of combustible poison coatings, 10 B enrichment and coating thickness ( 10 B linear density is 0.077mg/mm)
  • the linear density of the coating 10 B of the burnable poison coating is 0.077mg/mm, the relative density is 74%, and the coating is composed of SiB 6 , YB 6 and CeB 6 respectively, the relative density and thickness of the coating provided in Table 4 , the nuclear properties of the above-mentioned materials with natural abundance ( 10 B abundance is 18.4wt%) are basically equivalent to commercial ZrB 2 coatings.
  • the 10 B enrichment of boric acid, the raw material for production is reduced from 24.4wt% to Natural abundance, effectively reducing raw material costs, and having the same reactivity regulation function.
  • the core characteristic curves of the combustible poison coating and the ZrB 2 coating in this embodiment are shown in Figure 3.
  • the core characteristics of the three new integrated combustible poison absorber material solutions are basically consistent with the ZrB 2 coating solution. As shown in Table 7, based on the given design parameters, the neutron absorption capabilities of CeB 6 , YB 6 , and SiB 6 during zero combustion are approximately 166pcm, 148pcm, and 119pcm stronger than the ZrB 2 coating scheme. Comparing the burn-up range of 15,000 to 60,000MWd/tU, the neutron reactivity penalties of the three materials are slightly higher than ZrB 2. The reactivity penalties from high to low are CeB 6 , YB 6 and SiB 6 .
  • the combustible poison coating of the present application achieves the same reactivity control and moderator negative temperature coefficient control functions as commercial ZrB 2.
  • the initial reactivity value of the coating is the same as that of the same 10 B linear density.
  • ZrB 2 coating is basically the same.
  • the end-of-life reactivity penalty is essentially the same as for a ZrB coating with the same 10 B linear density.
  • the requirement for 10 B enrichment can be reduced, thereby effectively reducing raw material costs.
  • Example 3 Uses magnetron sputtering to coat CeB 6 coating on UO 2 core blocks
  • the CeB 6 coating on the outer surface of the fuel pellets was prepared by a magnetron sputtering instrument equipped with a radio frequency power supply, using a 50mm diameter CeB 6 target.
  • the cylindrical UO 2 fuel pellet is placed in the center of the bottom plate of the rotating sample holder, and the upper and lower surfaces of the sample are covered with metal sheets to avoid contamination by the coating.
  • Adjust the Ar gas flow to 60 sccm, the vacuum to 0.6 Pa, and the sample chamber temperature to maintain 200°C.
  • the CeB 6 target material The current was kept at 120mA to coat the sample. After 60 hours of coating, the temperature of the sample chamber was raised to 400°C and kept warm for 1 hour.
  • the microstructural structure of the cross-section of the coated core block is shown in Figure 4, and the average film thickness is approximately 10 ⁇ m.
  • the grazing incidence X-ray diffraction spectrum of the coated core block surface is shown in Figure 5. From the X-ray diffraction spectrum, it can be seen that except for the UO 2 matrix diffraction peak, the rest are diffraction peaks of CeB 6 , proving that the CeB 6 coating has high purity .
  • the above examples show that the combustible poison coating of the present application is feasible to manufacture, and the coating has a high degree of crystallization. It should be noted that the coating thickness can be controlled by adjusting the preparation process parameters and test implementation time.
  • the main difference of this application is that: three material solutions of SiB 6 , YB 6 and CeB 6 are optimized, and the uniform coating on the surface of the nuclear fuel pellet is achieved through the magnetron sputtering process, which provides the coating on the Specific application scenarios on fuel pellets and integrated into fuel elements.
  • the combustible toxic coating described in the patent of the present invention achieves the purpose of using lower 10 B abundance or even natural abundance materials to equivalently replace high-abundance ZrB 2 coatings in terms of reactivity adjustment function, while in terms of raw material cost, coating and It also has advantages in matrix bonding strength.

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Abstract

A burnable poison coating. The burnable poison coating is made of at least one of CeB6, SiB6, and YB6, and the density of the burnable poison coating is 70%-97% of the theoretical density of the used material. The present invention further relates to a method for preparing the burnable poison coating, and a nuclear fuel element comprising a nuclear fuel pellet to which the coating is applied.

Description

一种可燃毒物涂层及其制备方法和核燃料元件A burnable poison coating and its preparation method and nuclear fuel element 技术领域Technical field
本发明涉及核燃料技术领域，具体地说是一种可燃毒物涂层及其制备方法和核燃料元件。The present invention relates to the technical field of nuclear fuel, specifically a burnable poison coating and its preparation method and nuclear fuel elements.
背景技术Background technique
在压水反应堆首次装料或初始换料周期初期，堆芯初始剩余反应性较大，需要采用化学补偿毒物、可燃毒物或控制棒来控制这些剩余反应性。At the beginning of the first charging or initial refueling cycle of a pressurized water reactor, the initial residual reactivity of the core is relatively large, and chemical compensation poisons, combustible poisons or control rods need to be used to control these residual reactivity.
对可燃毒物而言，主要功能体现在两个方面：一是获得最大的燃料利用率、降低燃料循环成本。可燃毒物吸收过剩中子的能力随着运行平稳下降，以把可燃毒物束缚的反应性在燃耗过程中逐渐地、最终充分地释放出来；二是能够提供良好的功率分布控制能力，实现可燃毒物的消耗与燃料燃耗在速率及在空间关系上的最佳匹配。For combustible poisons, the main functions are reflected in two aspects: first, to obtain maximum fuel utilization and reduce fuel cycle costs. The ability of combustible poisons to absorb excess neutrons decreases steadily with operation, so that the reactivity bound by combustible poisons can be gradually and finally fully released during the burn-up process; secondly, it can provide good power distribution control capabilities to realize combustible poisons. The best match between consumption and fuel burn-up in terms of rate and spatial relationship.
文献(C.E.Sanders,J.C.Wagner,Study of the effect of integral burnable absorbers for PWR burnup credit,2002；M.O'Leary,M.L.Pitts,Effects of Burnable Absorbers on PWR Spent Nuclear Fuel,Office of Scientific&Technical Information Technical Reports,2000；J.R.Cacciapouti,Axial Burnup Profile Database for Pressurized Water Reactors,2000)对可燃毒物核素进行了研究和分析。现在普遍应用的可燃毒物核素主要有10B、157Gd和167Er。157Gd和167Er主要以氧化物形式掺杂于核燃料中，寿期末的总毒物残留稳定在初始毒性的4％以上。B元素消耗平稳下降并与燃料燃耗良好匹配，几乎没有残留惩罚后果，消耗速率始终平缓下降而被广泛应用，因此国内外用于压水堆的可燃毒物材料主要有硼不锈钢、碳化硼-氧化铝、硼硅酸盐玻璃和硼化锆涂层。 Literature (CESanders, JCWagner, Study of the effect of integral burnable absorbers for PWR burnup credit, 2002; M.O'Leary, MLPitts, Effects of Burnable Absorbers on PWR Spent Nuclear Fuel, Office of Scientific & Technical Information Technical Reports, 2000; JRCacciapouti, Axial Burnup Profile Database for Pressurized Water Reactors, 2000) conducted research and analysis on combustible poison nuclides. The currently commonly used combustible poison nuclides mainly include 10 B, 157 Gd and 167 Er. 157 Gd and 167 Er are mainly doped in nuclear fuel in the form of oxides, and the total toxic residue at the end of life is stable at more than 4% of the initial toxicity. The B element consumption decreases steadily and matches well with the fuel burnup. There is almost no residual penalty consequence. The consumption rate always decreases smoothly and is widely used. Therefore, the combustible toxic materials used in pressurized water reactors at home and abroad mainly include boron stainless steel and boron carbide-alumina. , borosilicate glass and zirconium boride coating.
目前商用整体型可燃毒物存在两种结构形式：(1)将可燃毒物吸收体与核燃料粉体混合在一起共烧结，形成包含可燃毒物吸收体的复合燃料芯块，如将Gd2O3或Er2O3弥散在UO2燃料中形成烧结体；(2)在核燃料芯块表面涂覆一层可燃毒物涂层，如将ZrB2涂覆在燃料芯块表面形成整体型燃料可燃毒物。AP1000系列核电型号商用的ZrB2涂层中10B富集度超过50wt％，使用富集硼酸作为原材料进行生产，制造成本较高，同时涂层和基体结合力也有待进一步提高。专利CN111573687A公开了一种中子反应性价值更高的高硼装载量的中子吸收体材料，中子吸收体材料为多B化合物，多B化合物的化学式为MBx，其中x不小于6，B的质量分数不低于75％，M为Al，Mg，Si，Y热中子吸收截面不超过1.5靶恩的元素及其混合物。该专利并未将上述材料应用于核燃料芯块表面，也未验证能否实现在核燃料芯块表面的涂覆工艺。Currently, there are two structural forms of commercial monolithic burnable poisons: (1) The burnable poison absorber and nuclear fuel powder are mixed and co-sintered to form a composite fuel pellet containing the burnable poison absorber, such as Gd 2 O 3 or Er 2 O 3 is dispersed in the UO 2 fuel to form a sintered body; (2) Coating a layer of combustible poison coating on the surface of the nuclear fuel pellet, such as coating ZrB 2 on the surface of the fuel pellet to form an integral fuel combustible poison. The concentration of 10 B in the commercial ZrB 2 coating for AP1000 series nuclear power models exceeds 50wt%. Enriched boric acid is used as the raw material for production. The manufacturing cost is high, and the bonding force between the coating and the substrate also needs to be further improved. Patent CN111573687A discloses a neutron absorber material with high boron loading and higher neutron reactivity value. The neutron absorber material is a multi-B compound. The chemical formula of the multi-B compound is MB x , where x is not less than 6, The mass fraction of B is not less than 75%, and M is Al, Mg, Si, Y elements whose thermal neutron absorption cross-section does not exceed 1.5 nm and their mixtures. The patent does not apply the above materials to the surface of nuclear fuel pellets, nor does it verify whether the coating process on the surface of nuclear fuel pellets can be realized.
发明内容Contents of the invention
为了解决上述问题，本申请提供一种可燃毒物涂层及其制备方法和核燃料元件，在实现与ZrB2涂层相似的反应性调节功能下，实现了长周期反应性控制和慢化剂负温度系数控制，可降低10B的富集度甚至使用天然丰度硼酸进行生产，降低材料成本。In order to solve the above problems, this application provides a burnable poison coating and its preparation method and nuclear fuel elements, which achieve long-term reactivity control and moderator negative temperature while achieving a reactivity adjustment function similar to that of the ZrB coating. Coefficient control can reduce the enrichment of 10 B or even use naturally abundant boric acid for production, reducing material costs.
本申请第一方面提供一种可燃毒物涂层，可燃毒物涂层由CeB6、SiB6、YB6中至少一种制成，可燃毒物涂层的相对密度为所使用材料的理论密度的70％～97％。The first aspect of this application provides a burnable poison coating. The burnable poison coating is made of at least one of CeB 6 , SiB 6 , and YB 6 . The relative density of the burnable poison coating is 70% of the theoretical density of the material used. ~97%.
作为一个实施例，可燃毒物涂层的厚度在5～20μm之间。As an example, the thickness of the burnable poison coating is between 5 and 20 μm.
作为一个实施例，可燃毒物涂层中10B线密度在0.02～0.1mg/mm之间。As an example, the linear density of 10 B in the combustible poison coating is between 0.02 and 0.1 mg/mm.
作为一个实施例，可燃毒物涂层中10B富集度在18.4wt％～30wt％之间。 As an example, the concentration of 10 B in the burnable poison coating is between 18.4wt% and 30wt%.
作为一个实施例，可燃毒物涂层的初始反应性价值与相同10B线密度的ZrB2涂层相差不超过200pcm；As an example, the initial reactivity value of the burnable poison coating does not differ by more than 200 pcm from a ZrB coating of the same 10 B linear density;
或，寿期末的反应性惩罚与相同10B线密度的ZrB2涂层相差不超过30pcm；Or, the reactivity penalty at the end of life does not differ by more than 30pcm from a ZrB 2 coating with the same 10 B linear density;
或，可燃毒物涂层在经历至少3次600℃热冲击试验后，通过胶带剥落试验后质量损失小于0.0006g。Or, after the combustible poison coating has undergone at least three thermal shock tests at 600°C, the mass loss after passing the tape peeling test is less than 0.0006g.
本申请还提供一种制备以上任一项可燃毒物涂层的方法，可燃毒物涂层采用磁控溅射工艺制备，具体操作过程包括：采用CeB6、SiB6、YB6中至少一种组成的涂层材料，燃料芯块置于样品室内旋转的样品支架底板中心，样品上底面覆盖金属薄片；调整样品室内的Ar气流量为60～80sccm，真空度为0.6～0.8Pa，温度保持在200～300℃，磁控管起弧后对涂层材料的电流保持在120～150mA对燃料芯块进行涂覆，涂敷60～70小时后，样品室温度升至400～420℃，保温1～1.2h。This application also provides a method for preparing any of the above combustible poison coatings. The combustible poison coating is prepared by a magnetron sputtering process. The specific operation process includes: using at least one of CeB 6 , SiB 6 , and YB 6 Coating material, fuel pellet is placed in the center of the rotating sample holder bottom plate in the sample chamber, and the upper and lower surfaces of the sample are covered with metal sheets; adjust the Ar gas flow rate in the sample chamber to 60~80 sccm, the vacuum degree to 0.6~0.8Pa, and the temperature to maintain at 200~ 300℃, after the magnetron arcs, the current to the coating material is maintained at 120~150mA to coat the fuel pellet. After coating for 60~70 hours, the temperature of the sample chamber rises to 400~420℃, and the temperature is maintained for 1~1.2 h.
本申请还提供一种核燃料元件，包括核燃料芯块，核燃料芯块表面涂覆有以上任一项的可燃毒物涂层。This application also provides a nuclear fuel element, including nuclear fuel pellets, the surface of which is coated with any of the above burnable toxic coatings.
作为一个实施例，核燃料芯块的材料为二氧化铀、二氧化钍、二氧化钚、二氧化铀-三氧化二钆、二氧化钍-三氧化二钆、二氧化钚-三氧化二钆及其混合物中的至少一种。As an example, the nuclear fuel pellets are made of uranium dioxide, thorium dioxide, plutonium dioxide, uranium dioxide-gadolinium trioxide, thorium dioxide-gadolinium trioxide, plutonium dioxide-gadolinium trioxide, and at least one of its mixtures.
作为一个实施例，还包括隔离核燃料芯块与冷却剂的结构材料(包壳材料)和用于堵住结构材料开口的密封材料(端塞材料)；所述结构材料和密封材料的热中子微观吸收截面不超过1.5靶恩，与所述核燃料芯块和冷却剂在室温到800℃之间不发生明显化学反应。As an embodiment, it also includes a structural material (cladding material) that isolates the nuclear fuel pellet from the coolant and a sealing material (end plug material) used to block the opening of the structural material; the thermal neutrons of the structural material and sealing material The microscopic absorption cross section does not exceed 1.5 nm, and no obvious chemical reaction occurs with the nuclear fuel pellets and coolant between room temperature and 800°C.
本发明的有益效果如下：The beneficial effects of the present invention are as follows:
(1)本发明提供的一种涂覆在核燃料芯块表面的可燃毒物涂层：所述可燃毒物涂层由CeB6、SiB6和YB6中的至少一种组成。CeB6、SiB6和 YB6三种材料的B密度分别为1.52g/cm3、1.7g/cm3和1.56g/cm3，分别高于ZrB2(1.17g/cm3)30％，45％和33％。在涂层10B线密度、相对密度和厚度接近情况下，可显著降低对10B富集度的需求。用于制备含B材料的硼酸价格与10B富集度成指数级增长，因此使用本发明所述可燃毒物涂层可显著降低原材料成本。同时所述涂层与基体芯块的结合力也优于ZrB2，在服役过程中具有更高的可靠性，更有利于堆芯安全。(1) The present invention provides a burnable poison coating coated on the surface of nuclear fuel pellets: the burnable poison coating is composed of at least one of CeB 6 , SiB 6 and YB 6 . CeB 6 , SiB 6 and The B densities of the three YB 6 materials are 1.52g/cm 3 , 1.7g/cm 3 and 1.56g/cm 3 respectively, which are 30%, 45% and 33% higher than ZrB 2 (1.17g/cm 3 ) respectively. When the 10 B linear density, relative density and thickness of the coating are close, the need for 10 B enrichment can be significantly reduced. The price of boric acid used to prepare B-containing materials increases exponentially with 10 B enrichment, so the use of the burnable poison coating of the present invention can significantly reduce raw material costs. At the same time, the bonding force between the coating and the matrix core block is also better than that of ZrB 2 , which has higher reliability during service and is more conducive to the safety of the reactor core.
(2)本发明的涂层与核燃料芯块基体在常温到800℃之间均具有良好相容性，涂层和燃料芯块之间通过金相显微镜未观察到界面反应。(2) The coating of the present invention has good compatibility with the nuclear fuel pellet matrix at room temperature to 800°C, and no interface reaction between the coating and the fuel pellet is observed through a metallographic microscope.
附图说明Description of the drawings
为了更清楚地说明本申请实施例的技术方案，下面将对本申请实施例中所需使用的附图作简单地介绍，显而易见，以下描述的附图仅仅是本申请的具体实施例，本领域技术人员在不付出创造性劳动的前提下，可以根据以下附图获得其他实施例。In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced below. It is obvious that the drawings described below are only specific embodiments of the present application. Without any creative effort, personnel can obtain other embodiments based on the following drawings.
图1为具有被本发明可燃毒物涂层覆盖的燃料芯块的燃料元件的示意图。Figure 1 is a schematic diagram of a fuel element having fuel pellets covered with a burnable poison coating of the present invention.
图2为沿图1中A-A方向的剖视放大图。FIG. 2 is an enlarged cross-sectional view along the direction A-A in FIG. 1 .
图3为相同10B线密度的SiB6、YB6、CeB6和ZrB2四种可燃毒物涂层的核特性曲线(燃耗曲线)，其中ZrB2作为对比。SiB6、YB6、CeB6三种方案的反应性价值曲线随燃耗的变化关系与ZrB2曲线基本相同，因此在图中发生重叠。即初始反应性价值与相同10B线密度ZrB2涂层相差不超过200pcm，寿期末的反应性惩罚与相同10B线密度的ZrB2涂层相差不超过30pcm。Figure 3 shows the core characteristic curves (burnup curves) of four combustible poison coatings of SiB 6 , YB 6 , CeB 6 and ZrB 2 with the same 10 B linear density, with ZrB 2 as a comparison. The relationship between the reactivity value curves of the three schemes SiB 6 , YB 6 , and CeB 6 as a function of fuel consumption is basically the same as that of the ZrB 2 curve, so they overlap in the figure. That is, the initial reactivity value does not differ from that of a ZrB 2 coating with the same 10 B linear density by no more than 200 pcm, and the reactivity penalty at the end of its life does not differ from that of a ZrB 2 coating that has the same 10 B linear density by no more than 30 pcm.
图4为表面涂覆CeB6涂层的UO2芯块横截面微观组织照片，每张图中均测量并标记了三处涂层的厚度。平均涂层厚约为10μm。Figure 4 is a cross-sectional microstructure photo of a UO 2 core block coated with CeB 6 coating on the surface. The thickness of three coatings is measured and marked in each picture. The average coating thickness is approximately 10 μm.
图5为表面涂覆CeB6涂层的UO2芯块表面掠入射X射线衍射谱。除UO2基体的衍射峰外，其余为CeB6的衍射峰。 Figure 5 shows the surface grazing incidence X-ray diffraction spectrum of UO 2 core blocks coated with CeB 6 coating. Except for the diffraction peaks of UO 2 matrix, the rest are the diffraction peaks of CeB 6 .
图6为表面涂覆了CeB6涂层的UO2芯块和涂覆了ZrB2涂层的UO2芯块经历5次600℃热冲击试验后胶带剥落试验结果。Figure 6 shows the tape peeling test results of UO 2 core blocks coated with CeB 6 coating and UO 2 core blocks coated with ZrB 2 coating after five times of 600°C thermal shock test.
附图标记：Reference signs:
1-上端塞，2-弹簧，3-包壳，4-涂覆涂层的芯块，41-可燃毒物涂层，5-支撑块，6-支撑管，7-下端塞，8-核燃料芯块，9-可燃毒物涂层，10-涂覆芯块与包壳管间隙。1-upper end plug, 2-spring, 3-cladding, 4-coated core block, 41-burnable poison coating, 5-support block, 6-support tube, 7-lower end plug, 8-nuclear fuel core block, 9-combustible poison coating, 10-the gap between the coated core block and the cladding tube.
此处的附图被并入说明书中并构成本说明书的一部分，示出了符合本申请的实施例，并与说明书一起用于解释本申请的原理。The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.
具体实施方式Detailed ways
为了更好地理解本申请的技术方案，下面结合附图对本申请实施例进行详细描述。In order to better understand the technical solutions of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.
图1具有被本发明可燃毒物涂层覆盖的燃料芯块的燃料元件的示意图。图2为沿图1中A-A方向的剖视放大图。Figure 1 is a schematic illustration of a fuel element having fuel pellets covered with a burnable poison coating of the present invention. FIG. 2 is an enlarged cross-sectional view along the direction A-A in FIG. 1 .
如图1和图2所示，上端塞1用于密封包壳管上端部；弹簧2用于应力缓冲；包壳3用于密封燃料芯块，防止核燃料芯块裂变气体泄漏；涂覆涂层的芯块4用于提供可控的链式中子反应；支撑块5和支撑管6分别用于加大燃料芯块与堆芯下板距离、增加燃料棒气腔体积，减小堆芯下板辐照损伤、降低燃料棒辐照后期内压；下端塞7用于密封包壳管下端部；核燃料芯块8为涂覆提供基体芯块；可燃毒物涂层9用于涂覆在燃料芯块表面，调控中子反应性；涂覆芯块与包壳管间隙10为燃料芯块辐照肿胀和裂变气体释放提供空间。As shown in Figures 1 and 2, the upper end plug 1 is used to seal the upper end of the cladding tube; the spring 2 is used to buffer the stress; the cladding 3 is used to seal the fuel pellets to prevent the leakage of fission gas from the nuclear fuel pellets; and apply a coating The pellet 4 is used to provide a controllable chain neutron reaction; the support block 5 and the support tube 6 are used to increase the distance between the fuel pellet and the lower core plate, increase the volume of the fuel rod gas chamber, and reduce the lower core plate. The plate is damaged by irradiation and reduces the internal pressure of the fuel rod in the later stage of irradiation; the lower end plug 7 is used to seal the lower end of the cladding tube; the nuclear fuel pellet 8 provides the matrix pellet for coating; the combustible poison coating 9 is used to coat the fuel core The surface of the block regulates neutron reactivity; the gap 10 between the coating pellet and the cladding tube provides space for the radiation swelling of the fuel pellet and the release of fission gas.
可燃毒物涂层9涂层主要成分包含B和Ce、Si、Y三种元素中的至少一种元素。所述涂层可展平堆芯中子注量分布，实现长周期反应性控制和慢化剂负温度系数控制。所述涂层与基体在常温至800℃之间均具有良 好相容性。涂层相对密度在70％～97％之间(可燃毒物涂层的密度为所使用材料的理论密度的70％～97％)，需要说明的是涂层相对密度如果过低，将在涂层中出现大量连通气孔，导致涂层几何稳定性和涂层-芯块附着力明显降低，不利于保障堆内服役可靠性。相对密度如果过高，则导致物理气相沉积效率过低，无法实现工程化生产，增加了生产成本。涂层厚度在1.5～20μm之间。涂层中10B线密度在0.02～0.1mg/mm之间。The main components of the combustible poison coating 9 include B and at least one of the three elements Ce, Si and Y. The coating can flatten the neutron fluence distribution in the core and achieve long-term reactivity control and moderator negative temperature coefficient control. The coating and substrate have good performance at room temperature to 800°C. Good compatibility. The relative density of the coating is between 70% and 97% (the density of the combustible poison coating is 70% to 97% of the theoretical density of the material used). It should be noted that if the relative density of the coating is too low, the coating will A large number of connected pores appear in the core, which leads to a significant reduction in the geometric stability of the coating and the adhesion between the coating and the core block, which is not conducive to ensuring the reliability of in-reactor service. If the relative density is too high, the physical vapor deposition efficiency will be too low, making it impossible to achieve engineering production and increasing production costs. The coating thickness is between 1.5~20μm. The linear density of 10 B in the coating is between 0.02 and 0.1 mg/mm.
实施例1不同涂层线密度下的涂层相对密度、10B富集度和涂层厚度关系Example 1 Relationship between coating relative density, 10 B enrichment and coating thickness under different coating linear densities
在可燃毒物涂层的涂层10B线密度为0.02mg/mm，分别由SiB6、YB6和CeB6组成，涂层相对密度取70％和97％时，涂层厚度如表1所示。当涂层的成分由SiB6、YB6和CeB6中的两种或三种的组合组成时，涂层相对密度在70％～97％之间时，涂层厚度在1.7μm～4.0μm之间。When the linear density of the 10 B coating of the burnable poison coating is 0.02mg/mm, which is composed of SiB 6 , YB 6 and CeB 6 respectively, and the relative density of the coating is 70% and 97%, the coating thickness is shown in Table 1 . When the composition of the coating is composed of two or three of SiB 6 , YB 6 and CeB 6 , and the relative density of the coating is between 70% and 97%, the coating thickness is between 1.7μm and 4.0μm. between.
表1可燃毒物涂层相对密度、10B富集度和涂层厚度关系(10B线密度为0.02mg/mm)

Table 1 The relationship between the relative density of combustible poison coatings, 10 B enrichment and coating thickness ( 10 B linear density is 0.02mg/mm)

在可燃毒物涂层的涂层10B线密度为0.10mg/mm，分别由SiB6、YB6和CeB6组成，涂层相对密度取70％和97％时，涂层厚度如表2所示。当涂层的成分由SiB6、YB6和CeB6中的两种或三种的组合组成时，涂层相对密度在70％～97％之间时，涂层厚度在8.6μm～20μm之间。When the linear density of the 10 B coating of the burnable poison coating is 0.10mg/mm, which is composed of SiB 6 , YB 6 and CeB 6 respectively, and the relative density of the coating is 70% and 97%, the coating thickness is shown in Table 2 . When the coating is composed of two or three of SiB 6 , YB 6 and CeB 6 , and the relative density of the coating is between 70% and 97%, the coating thickness is between 8.6μm and 20μm. .
表2可燃毒物涂层相对密度、10B富集度和涂层厚度关系(10B线密度为0.10mg/mm)

Table 2 The relationship between the relative density of combustible toxic coatings, 10 B enrichment and coating thickness ( 10 B linear density is 0.10mg/mm)

在可燃毒物涂层的涂层10B线密度为0.077mg/mm，分别由SiB6、YB6 和CeB6组成，涂层相对密度取70％和97％时，涂层厚度如表3所示。当涂层的成分由SiB6、YB6和CeB6中的两种或三种的组合组成时，涂层相对密度在70％～97％之间时，涂层厚度在6.6μm～15.4μm之间。The linear density of coating 10 B in the combustible poison coating is 0.077mg/mm, which is composed of SiB 6 and YB 6 respectively. And CeB 6 , when the relative density of the coating is 70% and 97%, the coating thickness is shown in Table 3. When the coating composition consists of two or three combinations of SiB 6 , YB 6 and CeB 6 , and the relative density of the coating is between 70% and 97%, the coating thickness is between 6.6μm and 15.4μm. between.
表3可燃毒物涂层相对密度、10B富集度和涂层厚度关系(10B线密度为0.077mg/mm)

Table 3 The relationship between the relative density of combustible poison coatings, 10 B enrichment and coating thickness ( 10 B linear density is 0.077mg/mm)

实施例2本申请可燃毒物涂层核特性与商用ZrB2涂层比较Example 2 Comparison of the core properties of the burnable poison coating of this application and the commercial ZrB coating
在可燃毒物涂层的涂层10B线密度为0.077mg/mm、相对密度为74％、涂层分别由SiB6、YB6和CeB6组成时，按照表4提供的涂层相对密度和厚度，天然丰度(10B丰度为18.4wt％)的上述材料的核特性与商用ZrB2涂层基本等效，此种情形下生产用原材料硼酸的10B富集度从24.4wt％降为天然丰度，有效降低了原材料成本，并且具有相同的反应性调节功能。本实施例的可燃毒物涂层与ZrB2涂层的核特性曲线如图3所示，三种新型整体型可燃毒物吸收体材料方案核特性均与ZrB2涂层方案基本一致。如表7所示，基于给定的设计参数CeB6、YB6、SiB6在零燃耗时中子吸收能力依次比ZrB2涂层方案强约166pcm、148pcm、119pcm。对比15000～60000MWd/tU燃耗区间，三种材料中子反应性惩罚皆略高于ZrB2，反应性惩罚由高至低依次为CeB6、YB6和SiB6。When the linear density of the coating 10 B of the burnable poison coating is 0.077mg/mm, the relative density is 74%, and the coating is composed of SiB 6 , YB 6 and CeB 6 respectively, the relative density and thickness of the coating provided in Table 4 , the nuclear properties of the above-mentioned materials with natural abundance ( 10 B abundance is 18.4wt%) are basically equivalent to commercial ZrB 2 coatings. In this case, the 10 B enrichment of boric acid, the raw material for production, is reduced from 24.4wt% to Natural abundance, effectively reducing raw material costs, and having the same reactivity regulation function. The core characteristic curves of the combustible poison coating and the ZrB 2 coating in this embodiment are shown in Figure 3. The core characteristics of the three new integrated combustible poison absorber material solutions are basically consistent with the ZrB 2 coating solution. As shown in Table 7, based on the given design parameters, the neutron absorption capabilities of CeB 6 , YB 6 , and SiB 6 during zero combustion are approximately 166pcm, 148pcm, and 119pcm stronger than the ZrB 2 coating scheme. Comparing the burn-up range of 15,000 to 60,000MWd/tU, the neutron reactivity penalties of the three materials are slightly higher than ZrB 2. The reactivity penalties from high to low are CeB 6 , YB 6 and SiB 6 .
表4核特性与商用ZrB2涂层等效的可燃毒物涂层参数(10B为天然富集度)

Table 4 Nuclear properties and combustible poison coating parameters equivalent to commercial ZrB 2 coatings ( 10 B is the natural enrichment)

表5核特性与商用ZrB2涂层等效的可燃毒物涂层参数(10B为20％富集度)
Table 5 Nuclear Properties Burnable Poison Coating Parameters Equivalent to Commercial ZrB 2 Coatings ( 10 B is 20% enrichment)
表6核特性与商用ZrB2涂层等效的可燃毒物涂层参数(10B为25％富集度)
Table 6 Nuclear Properties Burnable Poison Coating Parameters Equivalent to Commercial ZrB 2 Coatings ( 10 B for 25% Enrichment)
表7三种可燃毒物吸收材料与商用ZrB2反应性差别

Table 7 Differences in reactivity between three types of combustible poison absorbing materials and commercial ZrB 2

通过实施例2中数据可明显看出本申请的可燃毒物涂层实现了与商用ZrB2相同反应性控制和慢化剂负温度系数控制功能，涂层初始反应性价值与相同10B线密度的ZrB2涂层基本一致。寿期末反应性惩罚与相同10B线密度的ZrB2涂层基本一致。然而可降低10B富集度需求，进而有效降低原材料成本。From the data in Example 2, it can be clearly seen that the combustible poison coating of the present application achieves the same reactivity control and moderator negative temperature coefficient control functions as commercial ZrB 2. The initial reactivity value of the coating is the same as that of the same 10 B linear density. ZrB 2 coating is basically the same. The end-of-life reactivity penalty is essentially the same as for a ZrB coating with the same 10 B linear density. However, the requirement for 10 B enrichment can be reduced, thereby effectively reducing raw material costs.
实施例3采用磁控溅射法在UO2芯块上实现CeB6涂层的涂覆Example 3 Uses magnetron sputtering to coat CeB 6 coating on UO 2 core blocks
燃料芯块外表面的CeB6涂层通过配备射频电源的磁控溅射仪制备，采用50mm直径的CeB6靶材。圆柱状UO2燃料芯块置于旋转的样品支架底板中心，样品上底面覆盖金属薄片，避免被涂层沾染。调整Ar气流量为60sccm，真空为0.6Pa，样品室温度保持200℃。磁控管起弧后对CeB6靶材 的电流保持在120mA对样品进行涂覆。涂敷60小时后，样品室温度升至400℃，保温1h。通过SEM观察，涂覆芯块横截面的微观组织结构如图4所示，平均膜厚约为10μm。涂覆芯块表面掠入射X射线衍射谱如图5所示，从X射线衍射谱可看出除UO2基体衍射峰外，其余为CeB6的衍射峰，证明CeB6涂层具有较高纯度。上述实施例表明本申请的可燃毒物涂层具备制造可行性，涂层结晶程度较高。需要说明的是可通过调整制备工艺参数和试验实施时间对涂层厚度进行调控。The CeB 6 coating on the outer surface of the fuel pellets was prepared by a magnetron sputtering instrument equipped with a radio frequency power supply, using a 50mm diameter CeB 6 target. The cylindrical UO 2 fuel pellet is placed in the center of the bottom plate of the rotating sample holder, and the upper and lower surfaces of the sample are covered with metal sheets to avoid contamination by the coating. Adjust the Ar gas flow to 60 sccm, the vacuum to 0.6 Pa, and the sample chamber temperature to maintain 200°C. After the magnetron arc strikes, the CeB 6 target material The current was kept at 120mA to coat the sample. After 60 hours of coating, the temperature of the sample chamber was raised to 400°C and kept warm for 1 hour. Through SEM observation, the microstructural structure of the cross-section of the coated core block is shown in Figure 4, and the average film thickness is approximately 10 μm. The grazing incidence X-ray diffraction spectrum of the coated core block surface is shown in Figure 5. From the X-ray diffraction spectrum, it can be seen that except for the UO 2 matrix diffraction peak, the rest are diffraction peaks of CeB 6 , proving that the CeB 6 coating has high purity . The above examples show that the combustible poison coating of the present application is feasible to manufacture, and the coating has a high degree of crystallization. It should be noted that the coating thickness can be controlled by adjusting the preparation process parameters and test implementation time.
表8每轮次涂层磁控溅射工艺参数
Table 8 Magnetron sputtering process parameters for each round of coating
实施例4 CeB6涂覆UO2芯块与ZrB2涂覆UO2芯块剥落试验对比Example 4 Peeling test comparison between CeB 6 - coated UO pellets and ZrB 2 - coated UO pellets
用校准后胶带对CeB6涂覆UO2芯块(相对密度为90％,天然富集度、厚度10μm)进行剥落试验，在经历至少3次600℃热冲击试验后，其中左侧为CeB6涂层的结果，右侧为ZrB2涂层的结果。CeB6涂层与UO2基体之间附着力良好，在经历多次热冲击后，胶带剥落质量为0.0002g，低于ZrB2涂层质量损失(0.0004g)。剥离后胶带照片如图6所示。CeB6涂覆UO2芯块剥离试验后胶带上未见明显剥落物质，ZrB2涂覆UO2芯块剥离试验后胶带上可见明显剥落物质(图6中圆圈所示)。上述实施例表明本申请的可燃毒物涂层与燃料芯块基体之间结合紧密，优于ZrB2涂覆UO2芯块。 Peeling tests were performed on CeB 6 - coated UO pellets (relative density 90%, natural enrichment, thickness 10 μm) with calibrated tape, after at least 3 thermal shock tests at 600°C, with CeB 6 on the left Coating results, on the right are the results for the ZrB 2 coating. The adhesion between the CeB 6 coating and the UO 2 matrix is good. After experiencing multiple thermal shocks, the peeling mass of the tape is 0.0002g, which is lower than the mass loss of the ZrB 2 coating (0.0004g). The photo of the tape after peeling off is shown in Figure 6. After the peeling test of the CeB 6 -coated UO 2 core block, no obvious peeling material was seen on the tape. After the peeling test of the ZrB 2 -coated UO 2 core block, obvious peeling material was visible on the tape (shown as a circle in Figure 6). The above examples show that the combustible poison coating of the present application is closely combined with the fuel pellet matrix, which is better than ZrB 2 coated UO 2 pellets.
与专利CN111573687A相比，本申请的主要区别在于：优选出SiB6、YB6和CeB6三种材料方案，通过磁控溅射工艺实现了在核燃料芯块表面均匀涂覆，提供了涂覆在燃料芯块上并集成到燃料元件中的具体应用场景。本发明专利所述可燃毒物涂层实现了使用更低10B丰度甚至天然丰度材料在反应性调节功能上等效替代高丰度ZrB2涂层的目的，而在原材料成本、涂层与基体结合力方面也具有优势。Compared with the patent CN111573687A, the main difference of this application is that: three material solutions of SiB 6 , YB 6 and CeB 6 are optimized, and the uniform coating on the surface of the nuclear fuel pellet is achieved through the magnetron sputtering process, which provides the coating on the Specific application scenarios on fuel pellets and integrated into fuel elements. The combustible toxic coating described in the patent of the present invention achieves the purpose of using lower 10 B abundance or even natural abundance materials to equivalently replace high-abundance ZrB 2 coatings in terms of reactivity adjustment function, while in terms of raw material cost, coating and It also has advantages in matrix bonding strength.
以上所述仅为本申请的优选实施例而已，并不用于限制本申请，对于本领域的技术人员来说，本申请可以有各种更改和变化。凡在本申请的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本申请的保护范围之内。 The above descriptions are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included in the protection scope of this application.

Claims (9)

  1. 一种可燃毒物涂层，其特征在于，A combustible poison coating characterized by:
    所述可燃毒物涂层由CeB6、SiB6、YB6中至少一种制成，所述可燃毒物涂层的相对密度为所使用材料的理论密度的70％～97％。The burnable poison coating is made of at least one of CeB 6 , SiB 6 , and YB 6 , and the relative density of the burnable poison coating is 70% to 97% of the theoretical density of the material used.
  2. 如权利要求1所述的可燃毒物涂层，其特征在于，所述可燃毒物涂层的厚度在5～20μm之间。The burnable poison coating according to claim 1, wherein the thickness of the burnable poison coating is between 5 and 20 μm.
  3. 如权利要求1所述的可燃毒物涂层，其特征在于，所述可燃毒物涂层中10B线密度在0.02～0.1mg/mm之间。The combustible poison coating according to claim 1, wherein the 10 B linear density in the combustible poison coating is between 0.02 and 0.1 mg/mm.
  4. 如权利要求1所述的可燃毒物涂层，其特征在于，所述可燃毒物涂层中10B富集度在18.4wt％～30wt％之间。The burnable poison coating according to claim 1, wherein the 10 B enrichment degree in the burnable poison coating is between 18.4wt% and 30wt%.
  5. 如权利要求1所述的可燃毒物涂层，其特征在于，所述可燃毒物涂层的初始反应性价值与相同10B线密度的ZrB2涂层相差不超过200pcm；The burnable poison coating as claimed in claim 1, characterized in that the initial reactivity value of the burnable poison coating is no more than 200pcm different from that of a ZrB 2 coating with the same 10 B linear density;
    或，寿期末的反应性惩罚与相同10B线密度的ZrB2涂层相差不超过30pcm；Or, the reactivity penalty at the end of life does not differ by more than 30pcm from a ZrB 2 coating with the same 10 B linear density;
    或，所述可燃毒物涂层在经历至少3次600℃热冲击试验后，通过胶带剥落试验后质量损失小于0.0006g。Or, after the combustible poison coating has undergone at least three thermal shock tests at 600°C, the mass loss after passing the tape peeling test is less than 0.0006g.
  6. 一种制备如权利要求1至4中任一项所述可燃毒物涂层的方法，其特征在于，所述可燃毒物涂层采用磁控溅射工艺制备，具体操作过程包括：A method for preparing a combustible poison coating as claimed in any one of claims 1 to 4, characterized in that the combustible poison coating is prepared by a magnetron sputtering process, and the specific operation process includes:
    采用CeB6、SiB6、YB6中至少一种组成的涂层材料，燃料芯块置于样品室内旋转的样品支架底板中心，样品上底面覆盖金属薄片； Using at least one coating material composed of CeB 6 , SiB 6 , and YB 6 , the fuel pellet is placed in the center of the rotating sample holder bottom plate in the sample chamber, and the upper and lower surfaces of the sample are covered with metal sheets;
    调整样品室内的Ar气流量为60～80sccm，真空度为0.6～0.8Pa，温度保持在200～300℃，磁控管起弧后对涂层材料的电流保持在120～150mA对燃料芯块进行涂覆，涂敷60～70小时后，样品室温度升至400～420℃，保温1～1.2h。Adjust the Ar gas flow rate in the sample room to 60~80sccm, the vacuum degree to 0.6~0.8Pa, the temperature to 200~300℃, and the current to the coating material after the magnetron arc strikes to 120~150mA to carry out the test on the fuel pellets. Coating, after 60 to 70 hours of coating, the temperature of the sample chamber rises to 400 to 420°C and is kept warm for 1 to 1.2 hours.
  7. 一种核燃料元件，包括核燃料芯块，其特征在于，所述核燃料芯块表面涂覆有权利要求1-5任一项所述的可燃毒物涂层。A nuclear fuel element, including nuclear fuel pellets, characterized in that the surface of the nuclear fuel pellets is coated with the burnable poison coating according to any one of claims 1 to 5.
  8. 如权利要求7所述的核燃料元件，其特征在于，所述核燃料芯块的材料为二氧化铀、二氧化钍、二氧化钚、二氧化铀-三氧化二钆、二氧化钍-三氧化二钆、二氧化钚-三氧化二钆及其混合物中的至少一种。The nuclear fuel element according to claim 7, characterized in that the material of the nuclear fuel pellet is uranium dioxide, thorium dioxide, plutonium dioxide, uranium dioxide-gadolinium trioxide, thorium dioxide-gadolinium trioxide At least one of gadolinium, plutonium dioxide-gadolinium trioxide and mixtures thereof.
  9. 如权利要求7所述的核燃料元件，其特征在于，还包括：隔离核燃料芯块与冷却剂的结构材料和用于堵住结构材料开口的密封材料；所述结构材料和密封材料的热中子微观吸收截面不超过1.5靶恩，与所述核燃料芯块和冷却剂在室温到800℃之间不发生明显化学反应。 The nuclear fuel element according to claim 7, further comprising: a structural material for isolating the nuclear fuel pellets from the coolant and a sealing material for blocking openings in the structural material; thermal neutrons of the structural material and the sealing material. The microscopic absorption cross section does not exceed 1.5 nm, and no obvious chemical reaction occurs with the nuclear fuel pellets and coolant between room temperature and 800°C.
PCT/CN2023/116956 2022-09-05 2023-09-05 Burnable poison coating and preparation method therefor, and nuclear fuel element WO2024051678A1 (en)

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WO2019166111A1 (en) * 2018-02-28 2019-09-06 Westinghouse Electric Sweden Ab A fuel element containing uranium silicide and suitable for a nuclear reactor
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