Control rod absorber core block and control rod

Abstract

The present invention discloses a control rod absorber core block and a control rod. The control rod absorber core block includes a zirconium hydride column having at least two sub-cavities inside and at least two boron carbide blocks; the boron carbide blocks are respectively filled in the sub-cavities of the zirconium hydride column; in the zirconium hydride column, the height of the boron carbide blocks extends along the height direction of the zirconium hydride column. The control rod absorber core block of the present invention is mainly formed by a zirconium hydride column and the boron carbide blocks filled therein, and has the advantages of high reactivity value and low radiation swelling rate, etc. It can replace absorber core blocks made of existing absorber materials such as simple B4C in fast reactors, and also has the potential for application in thermal reactors, thereby increasing the service life of control rods and thus increasing the mechanical life of control rod assemblies.

Description

Technical Field

[0001] The present invention relates to the technical field of control rod absorber materials, and in particular to a control rod absorber core block and a control rod. Background Art

[0002] The control rod assembly is an important component used to control the power level of the reactor. It mainly adjusts its position in the reactor to achieve power control during the entire operation process. The control rod assembly is an important safety component of the reactor. In the event of an accident, it uses its own gravity to fall quickly to achieve an emergency shutdown of the entire core to ensure overall safety.

[0003] The control rod assembly is generally composed of a control rod bundle. The control rod is made by stacking the absorber core blocks with control properties, putting them into a stainless steel cladding, and then sealing them with end plugs. Because all the reactive control materials are contained in the control rod absorber core blocks, their design is particularly important.

[0004] Fast reactors (i.e. fast neutron reactors) and pressurized water reactors have different neutron energy spectra, and their control material selection is slightly different. At present, most fast reactors in the world are in the research stage, and there is no mature control rod absorber core block design. The absorber materials used are also of various types, mainly boron carbide, tantalum, chromium boride, europium, etc.; most of them are short cylindrical shapes. According to experimental descriptions, these core blocks have many disadvantages, such as low thermal conductivity of boron, low melting point of tantalum, high radioactive residue of europium, etc., which cannot meet the requirements of fast reactors. Targeted design is needed in terms of materials and structure to improve the performance of absorber core blocks and ensure reactor safety.

[0005] In summary, it is of great significance to develop new high-performance, cost-effective fast reactor control rod absorber core blocks. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide an improved control rod absorber core block and control rod.

[0007] The technical solution adopted by the present invention to solve the technical problem is: to provide a control rod absorber core block, comprising a zirconium hydride column having at least two sub-cavities inside, and at least two boron carbide blocks; the boron carbide blocks are respectively filled in the sub-cavities of the zirconium hydride column;

[0008] In the zirconium hydride column, the height of the boron carbide block extends along the height direction of the zirconium hydride column.

[0009] Preferably, the zirconium hydride column comprises a zirconium hydride cylinder, a zirconium hydride central column and at least two zirconium hydride connecting walls;

[0010] The zirconium hydride central column is disposed in the zirconium hydride cylinder, and the zirconium hydride connecting wall is connected between the outer surface of the zirconium hydride central column and the inner surface of the zirconium hydride cylinder, dividing the annular cavity between the zirconium hydride central column and the zirconium hydride cylinder into at least two sub-cavities;

[0011] Each of the boron carbide blocks is filled in one of the chambers.

[0012] Preferably, the zirconium hydride cylinder, the zirconium hydride central column and the zirconium hydride connecting wall are of the same height.

[0013] Preferably, the ratio of the diameter of the zirconium hydride central column to the outer diameter of the zirconium hydride column is 1:3 to 1:5.

[0014] Preferably, the wall thickness of the zirconium hydride connecting wall is greater than or equal to the wall thickness of the zirconium hydride cylinder.

[0015] Preferably, the zirconium hydride column comprises four zirconium hydride connecting walls;

[0016] The four zirconium hydride connecting walls divide the annular cavity between the zirconium hydride central column and the zirconium hydride cylinder into four sub-cavities.

[0017] Preferably, the corners of the boron carbide blocks and the corners in the chambers are chamfered.

[0018] Preferably, in the raw material B4C of the boron carbide block, 1 The enrichment of 0B is ≥80%.

[0019] Preferably, in the raw material of the zirconium hydride column, the stoichiometric ratio of Zr to H is 1:1.7 to 1:2.1.

[0020] The present invention also provides a control rod, comprising a cladding and a plurality of control rod absorber core blocks as described in any one of the above items;

[0021] A plurality of control rod absorber core blocks are stacked in the cladding along the axial direction of the cladding.

[0022] The control rod absorber core block of the present invention is mainly formed by a zirconium hydride column and boron carbide blocks filled therein, and has the advantages of high reactivity value and low radiation swelling rate. It can replace the absorber core blocks made of existing absorber materials such as simple B4C in fast reactors, and also has the potential for application in thermal reactors, thereby increasing the service life of the control rod and thus increasing the mechanical life of the control rod assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0024] Figure 1is a schematic diagram of the axial cross-sectional structure of a control rod absorber core block according to an embodiment of the present invention;

[0025] Figure 2 1 is a schematic diagram of a radial cross-sectional structure of a control rod absorber core block according to an embodiment of the present invention;

[0026] Figure 3 It is a comparative curve diagram of the relative reactivity values ​​of boron carbide and other absorber materials (Dy2TiO5, Hf, Ag-In-Cd, Dy2O3·HfO2) in the present invention. DETAILED DESCRIPTION

[0027] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0028] like Figure 1 , 2 As shown, a control rod absorber core block according to an embodiment of the present invention comprises a zirconium hydride column and at least two boron carbide blocks (ie, B4C blocks) 4.

[0029] Among them, the zirconium hydride column is a columnar structure with a hollow interior and at least two sub-cavities, and the boron carbide blocks 4 are respectively filled in the sub-cavities of the zirconium hydride column, that is, each sub-cavity is filled with a boron carbide block 4, so that the zirconium hydride column and the boron carbide block 4 constitute a solid columnar absorber core block.

[0030] In the zirconium hydride column, the height of the boron carbide block 4 extends along the height direction of the zirconium hydride column 4 , and the heights of the boron carbide block 4 and the zirconium hydride column can be consistent, so that the end face of the zirconium hydride column is flush with the end face of the boron carbide block 4 .

[0031] The zirconium hydride column may further include a zirconium hydride cylinder 1 , a zirconium hydride central column 2 and at least two zirconium hydride connecting walls 3 .

[0032] The zirconium hydride central column 2 is arranged in the zirconium hydride cylinder 1, and is extended along the height direction of the zirconium hydride cylinder 1, that is, the height directions and heights of the two are consistent. The zirconium hydride connecting wall 3 is connected between the outer surface of the zirconium hydride central column 2 and the inner surface of the zirconium hydride cylinder 1, and the annular cavity between the zirconium hydride central column 2 and the zirconium hydride cylinder 1 is divided into at least two sub-cavities; each boron carbide block 4 is filled in a sub-cavity.

[0033] The zirconium hydride connecting wall 3 is also extended along the height direction of the zirconium hydride cylinder 1, and its height is consistent with the height of the zirconium hydride cylinder 1. The sub-cavities formed by the zirconium hydride connecting wall 3 in the annular cavity penetrate the opposite ends of the zirconium hydride cylinder and are filled with boron carbide blocks 4 arranged in the sub-cavities.

[0034] Alternatively, the ratio of the diameter of the zirconium hydride central column 2 to the outer diameter of the zirconium hydride column body is 1:3 to 1:5. The wall thickness of the zirconium hydride connecting wall 3 is greater than or equal to the wall thickness of the zirconium hydride cylinder body 1 .

[0035] The corners of the boron carbide block 4 and the corners in the cavity are chamfered to prevent the control rod absorber core blocks from being broken due to excessive stress concentration at the corners during installation and stacking, thereby affecting the integrity of the core blocks.

[0036] exist Figure 1 In the illustrated embodiment, the zirconium hydride column includes four zirconium hydride connecting walls 3. The four zirconium hydride connecting walls 3 divide the annular cavity between the zirconium hydride central column 2 and the zirconium hydride cylinder 3 into four sub-cavities. Correspondingly, the control rod absorber core block includes four boron carbide blocks 4, and the four boron carbide blocks 4 are respectively filled in the four sub-cavities.

[0037] It can be understood that in other embodiments, the four boron carbide blocks 4 and the sub-cavities can be increased or decreased according to specific needs to achieve the purpose of increasing the amount of boron carbide, such as three boron carbide blocks 4, five boron carbide blocks 4, and so on.

[0038] In the control rod absorber core block of the present invention, the zirconium hydride column is mainly made of zirconium hydride; in the raw material of the zirconium hydride column, the stoichiometric ratio of Zr to H is 1:1.7 to 1:2.1, preferably 1:2, 1:1.8, etc. The boron carbide block 4 is mainly made of B4C; in the raw material B4C of the boron carbide block 4, 1 The enrichment of 0B is ≥80%.

[0039] When preparing the control rod absorber core block of the present invention, first use enriched boron carbide powder to pre-sinter in the shape of the boron carbide block 4, place the boron carbide block 4 in a zirconium hydride column mold, add zirconium hydride, and hot press to form a zirconium hydride column to form an integrated control rod absorber core block with the boron carbide block 4.

[0040] The control rod absorber core block of the present invention is used in a control rod. The control rod comprises a cladding and a plurality of the control rod absorber core blocks, wherein the plurality of control rod absorber core blocks are stacked in the cladding along the axial direction of the cladding.

[0041] In summary, the control rod absorber core block of the present invention is mainly formed by a zirconium hydride column and a boron carbide block 4 filled therein. The zirconium hydride column mainly forms a structure of an internal support (such as a zirconium hydride central column 2) and an external coating (such as a zirconium hydride cylinder 1), and the boron carbide blocks 4 are filled in the zirconium hydride column in an intermittent distribution form. Among them:

[0042] Boron carbide block 4 is used as the absorber matrix. Compared with other absorber materials, B4C is cheaper and is the most economical material. Its powder sintering characteristics also make it very easy to process and manufacture, making it easy to adjust the size and efficiency of the absorber. It is easy to manufacture, and the manufacturing and sintering process is mature. The porosity is adjustable, making it easy to adjust the deformation of the core block.

[0043] Comparison of the relative reactivity value of boron carbide with that of other absorber materials (Dy2TiO5, Hf, Ag-In-Cd, Dy2O3·HfO2) Figure 3 As shown. Figure 3 The relative reactivity value of each material changes with the effective operation time. It can be seen that B4C has the highest relative reactivity value in the initial stage, which meets the use requirements of fast reactors (i.e. fast neutron reactors). 10 B ratio, its reactivity value is higher.

[0044] Since the thermal neutron absorption cross section of B4C itself is larger than the fast neutron absorption cross section, the boron carbide block 4 is coated with a zirconium hydride column, and a zirconium hydride moderating structure is added to moderate fast neutrons, thereby improving the absorption efficiency of B4C and thus improving the value of the entire control rod.

[0045] By setting the zirconium hydride central column 2 and the zirconium hydride connecting wall 3, a heat conduction path is formed, which can conduct heat from the boron carbide block 4 to the core block surface, thereby increasing the heat dissipation efficiency of the core block, thereby reducing the temperature, reducing the radiation swelling of the control rod core block, and reducing gas generation, thereby achieving the effect of extending the service life and improving the safety of the control rod.

[0046] By adjusting the stoichiometric number of H in the raw material zirconium hydride column, the outermost structure of the pellet (i.e., the zirconium hydride cylinder 1) can have properties similar to zirconium metal, which can greatly reduce the interaction force between the pellet and the cladding, and prevent the pellet from breaking under excessive contact force. Once the control rod absorber pellet is pulverized due to irradiation, the zirconium hydride cylinder 3 can also achieve the purpose of wrapping the fragments and continuing to maintain the integrity of the control rod absorber pellet.

[0047] In the control rod, the control rod absorber core block contacts the cladding with the zirconium hydride cylinder 3. The zirconium hydride and the cladding material have stable chemical properties and good compatibility, and can coexist stably for a long time.

[0048] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A control rod absorber core block, characterized in that: It comprises a zirconium hydride column having at least two sub-cavities inside, and at least two boron carbide blocks; the boron carbide blocks are respectively filled in the sub-cavities of the zirconium hydride column; In the zirconium hydride column, the height of the boron carbide block extends along the height direction of the zirconium hydride column; The zirconium hydride column comprises a zirconium hydride cylinder, a zirconium hydride central column and at least two zirconium hydride connecting walls; the zirconium hydride central column is arranged in the zirconium hydride cylinder, and the zirconium hydride connecting wall is connected between the outer surface of the zirconium hydride central column and the inner surface of the zirconium hydride cylinder, dividing the annular cavity between the zirconium hydride central column and the zirconium hydride cylinder into at least two sub-cavities; each of the boron carbide blocks is filled in one of the sub-cavities; the ratio of the diameter of the zirconium hydride central column to the outer diameter of the zirconium hydride cylinder is 1:3 to 1:

5.

2. The control rod absorber core block according to claim 1, characterized in that: The zirconium hydride cylinder, the zirconium hydride central column and the zirconium hydride connecting wall have the same height.

3. The control rod absorber core block according to claim 1, characterized in that: The wall thickness of the zirconium hydride connecting wall is greater than or equal to the wall thickness of the zirconium hydride cylinder.

4. The control rod absorber core block according to claim 1, characterized in that: The zirconium hydride column includes four zirconium hydride connecting walls; The four zirconium hydride connecting walls divide the annular cavity between the zirconium hydride central column and the zirconium hydride cylinder into four sub-cavities.

5. The control rod absorber core block according to any one of claims 1 to 4, characterized in that: The corners of the boron carbide blocks and the corners in the chambers are chamfered.

6. The control rod absorber core block according to any one of claims 1 to 4, characterized in that: In the raw material B4C of the boron carbide block, 10 The enrichment of B is ≥80%.

7. The control rod absorber core block according to any one of claims 1 to 4, characterized in that: In the raw material of the zirconium hydride column, the stoichiometric ratio of Zr to H is 1:1.7 to 1:2.

1.

8. A control rod, characterized in that: A control rod absorber core comprising a cladding and a plurality of control rod absorber cores according to any one of claims 1 to 7; A plurality of control rod absorber core blocks are stacked in the cladding along the axial direction of the cladding.

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