A modular criticality safety tank

Abstract

The present invention discloses a modular critical safety storage tank, which includes a plurality of storage modules, each storage module is sequentially arranged and assembled together, each storage module includes a container and a neutron absorber, the neutron absorber is arranged in the container, and an annular storage area is formed between the neutron absorber and the container. The present invention has high space utilization, can effectively improve storage efficiency and universal applicability.

Description

Technical Field

[0001] The invention belongs to the technical field of spent fuel post-processing, and in particular relates to a modular critical safety storage tank. Background Art

[0002] The nuclear fuel cycle usually adopts a closed cycle mode. The spent fuel discharged from the reactor is sent to the reprocessing plant, and the uranium and plutonium are separated from the spent fuel and reused. Spent fuel reprocessing is an important stage in the closed nuclear fuel cycle process. The process of spent fuel reprocessing mainly includes head-end processing, chemical separation, and tail-end processing of uranium and plutonium. This process involves a large amount of storage and processing of solutions of fissile materials.

[0003] Due to the high concentration and high reactivity of the fissile material solution, the diameter of the cylinder that can meet the critical safety requirements is very small if a cylindrical storage tank is directly used. Therefore, an annular tank is generally used, that is, a neutron absorbing material is arranged in the middle to form an annular area with the outer container wall, and the fissile material solution is stored in the annular area. However, the space utilization efficiency of the annular tank is very low, the equipment room is large, and the total weight of the equipment is also large, which brings great difficulties to the support and fixation of the storage tank and the mechanical seismic resistance.

[0004] To solve the above problems, designers of reprocessing plants have been looking for more effective storage tanks for fissile material solutions. For example, the neutron absorbing materials in the annular tank are dispersed into several tube bundles to form a tube bundle tank, or neutron poison materials are used together with neutron moderator materials to enhance the neutron absorption effect of neutron poisons. Tube bundle tanks can effectively improve the storage efficiency of fissile material solutions, but the equipment form, tube bundle shape and layout are relatively fixed, lacking flexibility, and are difficult to be extended to all process flows involving the storage and treatment of fissile material solutions. At present, newly built spent fuel reprocessing plants still mainly use annular tanks with low storage efficiency. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a modular critical safety storage tank in view of the above-mentioned deficiencies in the prior art, which has high space utilization and can effectively improve storage efficiency and universal applicability.

[0006] The technical solution of the present invention to solve the above technical problems is:

[0007] A modular critical safety storage tank comprises a plurality of storage modules, each storage module is sequentially arranged and assembled together, each storage module comprises a container and a neutron absorber, the neutron absorber is arranged in the container, and an annular storage area is formed between the neutron absorber and the container.

[0008] Preferably, the storage module has a hexagonal cross section.

[0009] Preferably, the neutron absorber comprises a neutron absorbing material and a cladding, and the neutron absorbing material is filled in the cladding.

[0010] Preferably, the neutron absorber further comprises an inner shell, wherein the inner shell is disposed in the cladding, and the neutron absorbing material is filled between the cladding and the inner shell.

[0011] Preferably, the cross section of the cladding is hexagonal.

[0012] Preferably, the neutron absorbing material is one or a combination of boron carbide, boron-containing silicate materials, boron-containing aluminum-based composite materials, boron-containing organic materials, boron-containing concrete materials, metal cadmium, metal gadolinium, gadolinium oxide, boron-containing stainless steel, cadmium-containing stainless steel, and gadolinium-containing stainless steel.

[0013] Preferably, the cladding and the container are both made of one of titanium alloy, zirconium alloy, aluminum alloy, copper alloy, and stainless steel.

[0014] Preferably, the container is provided with an opening, and the opening is used to connect the annular storage areas in two adjacent storage modules.

[0015] Preferably, the shape of the opening is circular, semicircular, elliptical, rectangular, or a combination of these.

[0016] Compared with the prior art, the modular critical safety storage tank of this embodiment can reduce the volume of a single annular storage tank, and by adopting a hexagonal modular arrangement, the storage efficiency is effectively improved, and the volume and weight of the storage tank can be effectively saved. In addition, there is no restriction on the number and arrangement of the storage modules in the radial direction, and there is no restriction on the height of the storage modules in the height direction. The number, arrangement, and height size combination of the storage modules can be arbitrarily selected according to actual needs. It has high flexibility and universal applicability, and can be extended to all process flows involving the storage and treatment of fissile material solutions, which helps to improve the overall storage efficiency of the spent fuel reprocessing plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of a first modular critical safety tank in an embodiment of the present invention;

[0018] Figure 2 This is a schematic structural diagram of a second modular critical safety tank in an embodiment of the present invention;

[0019] Figure 3 Schematic diagram of the structure of the third modular critical safety tank in an embodiment of the present invention.

[0020] In the figure: 1-container; 2-neutron absorbing material; 3-cladding; 4-opening; 5-annular storage area. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0022] Example 1

[0023] like Figure 1 , Figure 2 , Figure 3 As shown, this embodiment discloses a modular critical safety storage tank, which includes a plurality of storage modules, each of which is arranged and assembled together in sequence, each of which includes a container 1 and a neutron absorber, the neutron absorber is arranged in the container 1, and an annular storage area 5 is formed between the neutron absorber and the wall of the container 1 in which it is located, and the annular storage area 5 is used to store fissile material solutions, such as high-concentration plutonium solutions and dissolved liquids in a reprocessing plant.

[0024] In some embodiments, Figure 2 As shown, the cross-section of the storage module is hexagonal, preferably a regular hexagon. More precisely, the cross-section of the container 1 is preferably a regular hexagon, so that in the radial direction of the storage tank, any number of storage modules with any height size can be assembled in any arrangement according to needs. In other words, the storage tank has no restrictions on the number and arrangement of storage modules in the radial direction, and no restrictions on the height of the storage modules in the height direction. The number, arrangement, and height size combination of the storage modules can be arbitrarily selected according to actual needs.

[0025] In this embodiment, the wall of the container 1 is made of any one of titanium alloy, zirconium alloy, aluminum alloy, copper alloy, and stainless steel.

[0026] In some embodiments, the neutron absorber includes a neutron absorbing material 2 and a cladding 3 . The neutron absorbing material 2 is filled in the cladding 3 , and the cladding 3 can protect the neutron absorbing material 2 .

[0027] Specifically, the neutron absorbing material 2 is any one or a combination of boron carbide, boron-containing silicate material, boron-containing aluminum-based composite material, boron-containing organic material, boron-containing concrete material, metal cadmium, metal gadolinium, gadolinium oxide, boron-containing stainless steel, cadmium-containing stainless steel, and gadolinium-containing stainless steel. The cross section of the cladding 3 is hexagonal, preferably a regular hexagon, and the neutron absorber is a solid hexagonal prism. The cladding 3 is made of any one of titanium alloy, zirconium alloy, aluminum alloy, copper alloy, and stainless steel.

[0028] In some embodiments, the neutron absorber further comprises an inner shell (not shown in the figure), the inner shell is arranged in the cladding 3, the neutron absorbing material 2 is filled between the cladding 3 and the inner shell, and the inner space of the inner shell is vacant, that is, the neutron absorber can be a hollow structure, and the neutron absorber can be a hollow hexagonal prism, but is not limited to the above-mentioned solid hexagonal prism. The shape and size of the inner shell are specifically selected according to the critical safety control requirements, and will not be repeated here.

[0029] In some embodiments, an opening 4 is provided on the wall of the container 1, and the openings 4 of adjacent storage modules are connected to each other. The opening 4 is used to connect the annular storage areas 5 of two adjacent storage modules. This not only allows the storage tank to only need one inlet and one outlet, which is convenient for transferring the solution in and out of the storage tank, but also allows the fissile material solution stored in the storage tank to be evenly distributed, ensuring that the critical safety control requirements are met.

[0030] Specifically, the openings can be provided on one or more walls of the container 1 in the hexagonal storage module, or on each wall of the container 1. The shape of the opening 4 is circular, semicircular, elliptical, rectangular, or any other shape or a combination of several. The number of the openings 4 can be one or more, which is selected according to actual needs.

[0031] Several groups of examples are provided below to describe the modular critical safety tank of this embodiment in detail, as follows:

[0032] Example 1

[0033] like Figure 1As shown, the container 1 and the cladding 3 are both made of stainless steel, the neutron absorber is of solid structure, and the neutron absorber material 2 is made of boron-containing concrete. Each wall of the container 1 in the hexagonal storage module is provided with an opening 4, which is rectangular in shape and runs from the top of the container 1 to the bottom of the container 1. The number of storage modules is 10, the width of the opposite side of the container 1 wall in each hexagonal storage module is 400mm, the width of the opposite side of the cladding 3 in the neutron absorber is 340mm, the height of the container 1 and the neutron absorber in the storage tank is 1800mm, and the total storage area volume formed by splicing 10 hexagonal storage modules is 692L, and the solution area in the cross-sectional area of ​​the storage tank (i.e., the sum of the cross-sectional areas of each annular storage area 5) accounts for 27.7%.

[0034] Taking the storage of high-concentration plutonium solution as an example, compared with the high-concentration plutonium solution annular storage tank currently used in spent fuel reprocessing plants, in which the solution area accounts for only 10.2% of the cross-sectional area, the storage efficiency of this storage tank is increased by 170%.

[0035] According to the criticality safety analysis, under the calculation condition of full water reflector, the effective neutron multiplication coefficient k is considered after the concentration fluctuation of high concentration plutonium solution. eff The maximum is 0.7729, which is equivalent to the reactivity of the high-concentration plutonium solution annular storage tank currently used in the spent fuel reprocessing plant. That is to say, the modular criticality safety storage tank of this embodiment can meet the criticality safety control requirements.

[0036] Example 2

[0037] like Figure 2 As shown, compared with Example 1, the difference is that the neutron absorption material 2 is made of boron-containing polyethylene material, so that the storage efficiency is further improved, and the number of storage modules is 24, the width of the opposite sides of the wall of the container 1 in each hexagonal storage module is 400mm, the width of the opposite sides of the cladding 3 in the neutron absorber is 300mm, the height of the container 1 and the neutron absorber in the storage tank is 2200mm, the total volume of the storage area formed after the 24 hexagonal storage modules are spliced ​​is 3200L, and the solution area in the cross-sectional area of ​​the storage tank (that is, the sum of the cross-sectional areas of each annular storage area 5) accounts for 43.7%.

[0038] Taking the storage of high-concentration plutonium solution as an example, compared with the high-concentration plutonium solution annular storage tank currently used in spent fuel reprocessing plants, in which the solution area accounts for only 10.2% of the cross-sectional area, the storage efficiency of this storage tank is increased by 325%, which is slightly higher than the high-concentration plutonium solution tube bundle tank currently used in spent fuel reprocessing plants, in which the solution area accounts for 41.1% of the cross-sectional area.

[0039] According to the criticality safety analysis, under the calculation condition of full water reflector, the effective neutron multiplication coefficient k is considered after the concentration fluctuation of high concentration plutonium solution. eff The maximum is 0.7860, which is equivalent to the reactivity of the high-concentration plutonium solution annular storage tanks and high-concentration plutonium solution tube bundle tanks currently used in spent fuel reprocessing plants. In other words, the modular criticality safety storage tank of this embodiment can meet the criticality safety control requirements.

[0040] Example 3

[0041] like Figure 3 As shown, the number of storage modules is 10. Compared with Example 1, the difference is that the width of the opposite side of the wall of the container 1 in each hexagonal storage module is 400mm, the width of the opposite side of the cladding 3 in the neutron absorber is 100mm, the height of the container 1 and the neutron absorber in the storage tank is 1600mm, and the total volume of the storage area formed after the 10 hexagonal storage modules are spliced ​​is 2078L. The solution area in the cross-sectional area of ​​the storage tank (that is, the sum of the cross-sectional areas of each annular storage area 5) accounts for 93%.

[0042] Taking the storage of dissolved liquid as an example, compared with the existing high-concentration plutonium solution annular storage tank used in spent fuel reprocessing plants, in which the solution area accounts for only 39.5% of the cross-sectional area, the storage efficiency of this storage tank is increased by 135%.

[0043] According to the criticality safety analysis, under the calculation condition of full water reflector, the effective neutron multiplication coefficient k is considered after the concentration fluctuation of high concentration plutonium solution. eff The maximum is 0.6090, which is equivalent to the reactivity of the annular storage tank for dissolved liquid currently used in the spent fuel reprocessing plant. That is to say, the modular criticality safety storage tank of this embodiment can meet the criticality safety control requirements.

[0044] In summary, compared with the prior art, the modular critical safety storage tank of this embodiment can reduce the volume of a single annular storage tank, and by adopting a hexagonal modular arrangement, the storage efficiency is effectively improved, and the volume and weight of the storage tank can be effectively saved. In addition, there is no restriction on the number and arrangement of the storage modules in the radial direction, and there is no restriction on the height of the storage modules in the height direction. The number, arrangement, and height size combination of the storage modules can be arbitrarily selected according to actual needs. It has high flexibility and universal applicability, and can be extended to all process flows involving the storage and treatment of fissile material solutions, which helps to improve the overall storage efficiency of the spent fuel reprocessing plant.

[0045] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A modular critical safety tank, characterized in that: It includes several storage modules, each of which has a hexagonal cross section. Each storage module is sequentially arranged and assembled together. Each storage module comprises a container (1) and a neutron absorber, wherein the neutron absorber is arranged in the container and an annular storage area (5) is formed between the neutron absorber and the container; The neutron absorber comprises a neutron absorbing material (2) and a cladding (3), wherein the neutron absorbing material is filled in the cladding.

2. The modular critical safety tank according to claim 1, characterized in that: The neutron absorber further comprises an inner shell, wherein the inner shell is arranged in the cladding, and the neutron absorbing material is filled between the cladding and the inner shell.

3. The modular critical safety tank according to claim 1, characterized in that: The cross section of the cladding is hexagonal.

4. The modular criticality safety tank according to claim 1, characterized in that: The neutron absorbing material is one or a combination of the following: boron carbide, boron-containing silicate material, boron-containing aluminum-based composite material, boron-containing organic material, boron-containing concrete material, metal cadmium, metal gadolinium, gadolinium oxide, boron-containing stainless steel, cadmium-containing stainless steel, and gadolinium-containing stainless steel.

5. The modular criticality safety tank according to claim 1, characterized in that: The cladding and the container are both made of one of titanium alloy, zirconium alloy, aluminum alloy, copper alloy and stainless steel.

6. The modular critical safety tank according to any one of claims 1 to 5, characterized in that: The container is provided with an opening (4), and the opening is used to connect the annular storage areas in two adjacent storage modules.

7. The modular criticality safety tank according to claim 6, characterized in that: The shape of the opening is one or a combination of circular, semicircular, elliptical and rectangular.

Images