A neutron poison material and its preparation method, and nuclear criticality safety storage tank

Abstract

The present invention discloses a neutron poison material, the chemical composition of which includes, by weight, 10 to 27 parts of water, 20 to 25 parts of cement, 8 to 15 parts of boron additives, and 45 to 50 parts of sand. The present invention also discloses a preparation method of the neutron poison material, a nuclear critical safety tank containing the neutron poison material, and the neutron poison material and the nuclear critical safety tank. The present invention has good neutron absorption effect, stable structure, high strength and durability, and the preparation method is simple in process, the raw materials are easily available, and the cost is low.

Description

Technical Field

[0001] The invention belongs to the field of nuclear engineering, and in particular relates to a neutron poison material and a preparation method thereof, and a nuclear criticality safety storage tank. Background Art

[0002] Spent fuel reprocessing plants mainly extract plutonium from irradiated nuclear fuel in nuclear reactors. 239 Pu) and recovery of useful uranium ( 235 U), neptunium and other transuranium elements, because 235 U. 239 Pu and other nuclides are fissile nuclides, and nuclear criticality accidents may occur during processing. Once a criticality accident occurs, it may damage equipment, cause material loss and radioactive contamination, and the strong radiation generated during a nuclear criticality accident may also cause casualties.

[0003] In order to reduce the risk of nuclear criticality accidents to the lowest possible level, geometric safety devices lined with solid neutron poisons or a combination of concentration and geometry are usually used to control nuclear criticality. At present, concrete is the most widely used material for nuclear radiation protection and shielding. It has great advantages in structural stability and durability, but its neutron absorption performance needs to be improved. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a neutron poison material and a preparation method thereof, as well as a nuclear critical safety storage tank in view of the above-mentioned deficiencies in the prior art. The neutron poison material and the nuclear critical safety storage tank have good neutron absorption effect, stable structure, high strength and durability, and the preparation method has a simple process, readily available raw materials and low cost.

[0005] The technical solution adopted to solve the technical problem of the present invention is:

[0006] According to one aspect of the present invention, a neutron poison material is provided, and its technical solution is as follows:

[0007] A neutron poison material, the chemical composition of which includes, by weight, 10 to 27 parts of water, 20 to 25 parts of cement, 8 to 15 parts of boron additives, and 45 to 50 parts of sand.

[0008] Preferably, the cement is silicate cement, the boron additive is boron nitride, and the sand is fine river sand.

[0009] According to another aspect of the present invention, a method for preparing a neutron poison material is provided, and its technical solution is as follows:

[0010] A method for preparing a neutron poison material, comprising:

[0011] S1 dry mixing: by weight, 20-25 parts of cement, 8-15 parts of boron additive, and 45-50 parts of sand are mixed evenly to obtain a dry material;

[0012] S2 Sampling and analysis: extract samples from dry materials and detect the boron content in the samples. If the boron content is qualified, proceed to step S3. If not, continue dry mixing until the boron content is qualified.

[0013] S3 wet mixing: adding 10 to 27 parts of water by weight and mixing evenly to obtain boron-containing cement mortar;

[0014] S4 processing and molding: Casting the boron-containing cement mortar to obtain the neutron poison material product.

[0015] Preferably, the cement is silicate cement, the boron additive is boron nitride, and the sand is fine river sand.

[0016] Preferably, in step S2, the sampling refers to selecting at least four different parts of the dry material for sampling, and the qualified boron content detection refers to the boron content of each sample per gram of dry material is ≥0.047g.

[0017] Preferably, the consistency of the boron-containing cement mortar in step S3 is 70-80 mm.

[0018] Preferably, in the step S4, the pouring specifically comprises: pouring the boron-containing cement mortar in layers in the forming mold, with the height of each layer being 90-100 mm.

[0019] According to another aspect of the present invention, a nuclear criticality safety storage tank is provided, and its technical solution is as follows:

[0020] A nuclear criticality safety storage tank comprises a tank body and a solid neutron poison, wherein the solid neutron poison is made of the neutron poison material mentioned above.

[0021] Preferably, the tank body is in the shape of an annular tank, including an inner tank wall and an outer tank wall, the solid neutron poison is filled inside the inner tank wall, and the distance between the inner tank wall and the outer tank wall is 50 mm.

[0022] Preferably, the radius of the inner wall of the tank body is ≥800 mm, the solid neutron poison is in the shape of a ring, and the distance between the inner diameter and the outer diameter of the ring-shaped solid neutron poison is 400 mm.

[0023] Beneficial effects:

[0024] The neutron poison material of the present invention has good neutron absorption effect, and has the advantages of stable concrete structure, high strength and durability, and the raw materials are easily available and the cost is low.

[0025] The preparation method of the neutron poison material of the present invention has a simple process, readily available raw materials and low cost. The neutron poison material prepared by the method has a better neutron absorption effect than the conventional radiation-proof and shielding concrete material due to the addition of a boron additive, and has the advantages of a stable concrete structure, high strength and durability. In addition, the material has a wide range of applications and can be used in occasions where different neutron absorption properties are required.

[0026] The nuclear criticality safety storage tank of the present invention adopts the above-mentioned neutron poison material, has good neutron absorption effect, can effectively prevent the occurrence of nuclear criticality accidents, and has stable structure, high strength and durability, wide application range and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a flow chart of a method for preparing a neutron poison material according to an embodiment of the present invention;

[0028] Figure 2 A top view of a nuclear criticality safety storage tank in an embodiment of the present invention;

[0029] Figure 3 It is a cross-sectional view of a nuclear criticality safety storage tank in an embodiment of the present invention;

[0030] Figure 4 A top view of another nuclear criticality safety storage tank in an embodiment of the present invention;

[0031] Figure 5 It is a cross-sectional view of another nuclear criticality safety storage tank in an embodiment of the present invention.

[0032] In the figure: 1-outer wall of tank body; 2-liquid; 3-inner wall of tank body; 4-solid neutron poison. DETAILED DESCRIPTION

[0033] 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.

[0034] Example 1

[0035] This embodiment discloses a neutron poison material, the chemical composition of which, by weight, includes:

[0036] 10-27 parts of water, 20-25 parts of cement, 8-15 parts of boron additive, 45-50 parts of sand.

[0037] Among them, the boron additive is boron nitride; since the neutron poison material in this embodiment can enhance the neutron absorption capacity by adding boron nitride, the cement itself does not need to have a high crystal water content. Therefore, the cement can be silicate cement, preferably Type I silicate cement (codenamed P·I) without any mixed materials. Compared with the radiation-proof special cement in traditional technology (such as high-alumina cement, barium cement, strontium cement, etc.), this cement is simple to prepare, convenient to construct, and cost-effective; the sand is fine river sand.

[0038] The neutron poison material of this embodiment has good neutron absorption effect, stable structure, high strength and durability, and the raw materials are easily available and the cost is low.

[0039] Example 2

[0040] like Figure 1 As shown, this embodiment discloses a method for preparing a neutron poison material, which is used to prepare the neutron poison material described in Example 1, comprising steps S1-S4, wherein:

[0041] S1 dry mixing: by weight, 20-25 parts of cement, 8-15 parts of boron additive, and 45-50 parts of sand are stirred and mixed uniformly to obtain dry materials.

[0042] Specifically, the cement is silicate cement, preferably type I silicate cement (codenamed P·I) without any mixed materials. The boron additive is boron nitride. Since the boron additive will affect the coagulation process and physical properties of the cement, too much boron content will destroy the structural stability of the neutron poisoning material, and too little boron content will affect the uneven mixing, which may cause hidden dangers of nuclear critical safety accidents. Therefore, the method needs to strictly control the amount of boron additives, and its amount mainly considers two factors: meeting the nuclear critical safety requirements and not destroying the structural stability of the neutron poisoning material. Among them, meeting the nuclear critical safety requirements can be determined based on the effective value of K calculated by nuclear critical safety, and the structural stability of the neutron poisoning material is determined based on the test results of the neutron poisoning material product obtained by the actual preparation process. For example, Figure 2 , Figure 3 As shown, the neutron poison material is used to fill the inner side of the annular nuclear critical safety storage tank of the cylindrical structure. The inner diameter of the storage tank is 500mm, the height is 600mm, and the width of the annular part (i.e., the part filled with liquid) is 50mm. According to the results of critical safety calculation and preparation test results, the chemical composition of the neutron poison material is finally determined to be water: cement: boron nitride: sand = 2:3:1:6 by weight, that is, 16.6 parts of water, 25 parts of cement, 8.3 parts of boron additives, and 50 parts of sand. The sand is preferably fine river sand, and the fineness modulus of fine river sand is μ fThe preferred value is 2.2-1.6. The uniformity of dry mixing can be judged based on the color of the mixture. When the color of the mixture is consistent, it can be judged that the dry mixing is uniform.

[0043] S2 Sampling and analysis: extract samples from the dry material. Specifically, select at least four different parts of the dry material for sampling. The amount of each sample is preferably 10 ml, and the boron content in each sample is detected. If the boron content per gram of dry material in each sample is ≥ 0.047 g, that is, the boron content is qualified, then enter step S3. If not, continue dry mixing until the boron content is detected to be qualified.

[0044] S3 wet mixing: add 10 to 27 parts of water (16.6 parts of water in this embodiment) by weight, and mix evenly to obtain a boron-containing cement mortar with good workability. The consistency of the boron-containing cement mortar is controlled at 70-80 mm.

[0045] S4 processing and molding: Pour the boron-containing cement mortar in layers into a molding mold (such as a nuclear critical safety storage tank), with each layer having a height of 90-110 mm, preferably 100 mm. Stir continuously during pouring, and pour the next layer after stirring until the boron-containing cement mortar is flush with the top surface of the molding mold space to obtain a cast neutron poison material product.

[0046] The preparation method of the neutron poison material of this embodiment has a simple process, readily available raw materials and low cost. The neutron poison material prepared by this method has better neutron absorption effect than the conventional radiation-proof and shielding concrete materials due to the addition of boron additives. In addition, the neutron poison material has the advantages of stable structure, high strength and durability of concrete materials, and has a wide range of applications, and can be used in occasions where different neutron absorption properties are required.

[0047] Example 3

[0048] This embodiment discloses a method for preparing a neutron poison material. Compared with Embodiment 2, the difference is that:

[0049] The chemical components of the neutron poison material of this embodiment are as follows by weight: 27 parts of water, 20 parts of cement, 8 parts of boron nitride, and 45 parts of sand.

[0050] Example 4

[0051] This embodiment discloses a method for preparing a neutron poison material. Compared with Embodiment 2, the difference is that:

[0052] The chemical components of the neutron poison material of this embodiment are as follows by weight: 15 parts of water, 25 parts of cement, 10 parts of boron nitride, and 50 parts of sand.

[0053] Example 5

[0054] This embodiment discloses a method for preparing a neutron poison material. Compared with Embodiment 2, the difference is that:

[0055] The chemical components of the neutron poison material of this embodiment are as follows by weight: 10 parts of water, 25 parts of cement, 15 parts of boron nitride, and 50 parts of sand.

[0056] Example 6

[0057] This embodiment discloses a method for preparing a neutron poison material. Compared with Embodiment 2, the difference is that:

[0058] The chemical components of the neutron poison material of this embodiment are as follows by weight: 20 parts of water, 21 parts of cement, 12 parts of boron nitride, and 47 parts of sand.

[0059] Example 7

[0060] like Figure 2-5 As shown, this embodiment discloses a nuclear criticality safety storage tank for spent fuel post-processing, which includes a tank body and a solid neutron poison, and the solid neutron poison is made of the neutron poison material described in Example 1 or 2.

[0061] In some embodiments, Figure 2 , Figure 3 As shown, the tank body of the nuclear critical safety storage tank is an annular groove, and the radioactive liquid 2 is placed in the annular groove space, which includes the inner wall 3 of the tank body and the outer wall 1 of the tank body. The solid neutron poison 4 is formed on the inner side of the inner wall 3 of the tank body (in a cylindrical shape) and is not easily damaged. The radius of the inner wall and the outer wall of the tank body increases with the increase of the volume of the storage tank, and the radius of the space filled with the neutron poison material also increases accordingly. However, the distance between the inner wall 3 of the tank body and the outer wall 1 of the tank body (i.e., the tank width, the width of the annular space for placing the radioactive liquid) remains unchanged and is always 50 mm.

[0062] In some embodiments, Figure 4 , Figure 5 As shown, the radius of the inner wall 3 of the tank body is ≥800 mm, the solid neutron poison 4 is formed into a circular ring, and the distance between the inner diameter and the outer diameter of the circular ring-shaped solid neutron poison is 400 mm, that is, the width of the circular ring-shaped solid neutron poison will not continue to increase with the increase of the storage tank volume.

[0063] The nuclear criticality safety storage tank of this embodiment has good neutron absorption effect and can effectively prevent the occurrence of nuclear criticality accidents because the solid neutron poison adopts the neutron poison material described in Example 1 or 2. In addition, it has a stable structure, high strength and durability, a wide range of applications, and low cost.

[0064] 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 neutron poison material, characterized in that: Its chemical composition by weight includes: 10-27 parts of water, 21-25 parts of cement, 10-15 parts of boron additive, 45-50 parts of sand; Wherein, the cement is silicate cement, the boron additive is boron nitride, and the sand is fine river sand.

2. A method for preparing a neutron poison material, comprising: S1 dry mixing: by weight, 21-25 parts of cement, 10-15 parts of boron additive, and 45-50 parts of sand are mixed evenly to obtain a dry material, wherein the cement is silicate cement, the boron additive is boron nitride, and the sand is fine river sand; S2 Sampling and analysis: Take samples from dry materials and test the boron content in the samples. If the boron content is qualified, proceed to step S3, if not, continue dry mixing until the boron content is qualified; S3 wet mixing: adding 10 to 27 parts of water by weight and mixing evenly to obtain boron-containing cement mortar; S4 processing and molding: Casting the boron-containing cement mortar to obtain the neutron poison material product.

3. The method for preparing the neutron poison material according to claim 2, characterized in that: In step S2, The sampling refers to selecting at least four different parts of the dry material for sampling; The qualified boron content detection means that the boron content per gram of dry material in each sample is ≥0.047g.

4. The method for preparing a neutron poison material according to claim 2, characterized in that: The consistency of the boron-containing cement mortar in step S3 is 70-80 mm.

5. The method for preparing a neutron poison material according to claim 2, characterized in that: In step S4, the pouring specifically includes: Pour the boron cement mortar in layers into the forming mold, with each layer having a height of 90-100mm.

6. A nuclear criticality safety storage tank, comprising a tank body and solid neutron poison, characterized in that: The solid neutron poison is made of the neutron poison material according to claim 1.

7. The nuclear criticality safety storage tank according to claim 6, characterized in that: The tank body is in the shape of an annular tank, and includes a tank body inner wall and a tank body outer wall. The solid neutron poison is filled inside the tank body inner wall, and the distance between the tank body inner wall and the tank body outer wall is 50 mm.

8. The nuclear criticality safety storage tank according to claim 7, characterized in that: The radius of the inner wall of the tank body is ≥800 mm, the solid neutron poison is in the shape of a ring, and the distance between the inner diameter and the outer diameter of the ring-shaped solid neutron poison is 400 mm.

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