Neutron shielding concrete containing artificial water-encapsulated aggregate and method of making same

Abstract

This invention relates to a neutron shielding concrete containing artificial water-infused aggregate and its preparation method. The artificial water-infused aggregate comprises a metal shell, a porous structure, and a water-based liquid. The metal shell is a sealed structure used to contain the porous structure. The porous structure is formed by mixing ceramsite raw material with 1%–10% by weight of powdered B4C or Gd2O3, wherein B4C accounts for 20%–80% of the total weight of the powder, the powder particle size is 10 micrometers, and the mixture is shaped into a specified form, dried, and then fired. The water-based liquid is natural water, tap water, or boric acid solution contained within the pores of the porous structure. This artificial water-infused aggregate is readily available, its preparation process is simple, and the production process is highly industrialized. The resulting concrete exhibits superior moisture content, workability, fast neutron moderation capability, and thermal neutron absorption capability compared to existing concrete, meeting the requirements for nuclear radiation, particularly neutron shielding structures, in special nuclear facilities.

Description

Technical Field

[0001] This invention belongs to the field of radiation-shielding concrete preparation technology, and specifically relates to a neutron shielding concrete containing artificial water-infused aggregate and its preparation method. Background Technology

[0002] In the construction of facilities such as nuclear power plants, concrete structures are an important component of radiation shielding. Water is the best moderator for fast neutrons produced by nuclear reactions. Using serpentine as a concrete aggregate can provide good neutron shielding and is already being used in a few nuclear facilities.

[0003] Serpentine is a mineral containing approximately 13% bound water by weight. However, as a natural mineral, serpentine aggregate has many impurities and high production costs. The resulting serpentine concrete has poor workability and its moisture content is difficult to increase further, which cannot meet the needs of large-scale application in nuclear facilities.

[0004] Therefore, how to provide a neutron shielding concrete containing artificial water-infused aggregate that can be mass-produced and its preparation method, in order to meet the needs of large-scale application in nuclear facilities, is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This invention provides a neutron shielding concrete containing artificial water-infused aggregate and its preparation method, which enables large-scale production and solves the problem of large-scale application in nuclear facilities.

[0006] To solve the above technical problems, the present invention includes the following technical solutions:

[0007] A neutron shielding concrete containing artificial water-infused aggregate, wherein the components of the concrete are in the following mass ratio (kg / m³). 3 ):

[0008] The mixture comprises 900-1200 parts coarse aggregate, 600-800 parts serpentine fine aggregate, 200-260 parts cement, 80-120 parts mineral powder, 80-40 parts fly ash, 180-220 parts water, and 3-6 parts water-reducing agent; wherein the coarse aggregate is composed of artificial water-retaining aggregate and serpentine coarse aggregate, the mixing ratio can be arbitrary, and the particle size range is 3mm-40mm; the particle size range of the serpentine fine aggregate is 0.25mm-3mm.

[0009] Furthermore, the artificial water-infused aggregate includes a metal shell, a porous structure, and a water-based liquid. The metal shell is a sealed structure used to contain the porous structure. The porous structure is formed by mixing ceramsite raw material with 1% to 10% by weight of powdered B4C or Gd2O3, wherein the weight of B4C accounts for 20% to 80% of the total weight of the powder, the particle size of the powder is 10 micrometers, and the mixture is shaped into a specified shape, dried, and then fired. The water-based liquid is natural water, tap water, or boric acid solution contained in the pores of the porous structure.

[0010] Furthermore, the porosity of the porous structure is >30%, and the cylinder compressive strength is >10MPa.

[0011] Furthermore, the ceramsite is selected from at least one of alumina particles, silicon oxide particles, silicon carbide particles, and silicon nitride particles.

[0012] Furthermore, the metal outer shell is a metal spherical shell or other hollow, irregularly shaped closed structure, and the metal is made of stainless steel.

[0013] Furthermore, the outer radius of the metal spherical shell is R, and the thickness is t, where the value of R ranges from 1.5 mm to 20 mm. In the formula, α is the safety factor, ranging from 1.5 to 2.0; p = 1.55 MPa is the critical boiling pressure of water at 200℃; σ y =360MPa is the yield stress of the metal material. This condition is based on the formula for membrane stress generated by internal pressure on a spherical shell in theoretical mechanics, and the membrane stress must be less than the yield stress of the metal spherical shell material. It is obtained through conversion.

[0014] This invention also provides a method for preparing neutron-shielded concrete containing artificial water-infused aggregate, the method comprising the following steps:

[0015] Step S1: Mix and stir carbon nanotubes, water-reducing agent and water, and use ultrasound to promote the dispersion of carbon nanotubes to prepare a uniform suspension.

[0016] Step S2: Provide a mixed coarse aggregate made of artificial water-retaining aggregate, ordinary coarse aggregate and serpentine coarse aggregate. Add serpentine fine aggregate, cement, mineral powder and fly ash into the mixer and mix for 60 seconds.

[0017] Step S3: Add the suspension from step S1 and stir for 120–240 seconds.

[0018] Furthermore, the artificial water-infused aggregate comprises a metal shell, a porous structure, and a water-based liquid. The metal shell is a sealed structure used to contain the porous structure. The porous structure is formed by mixing ceramsite raw material with 1% to 10% by weight of powdered B4C or Gd2O3, wherein the weight of B4C accounts for 20% to 80% of the total weight of the powder, the particle size of the powder is 10 micrometers, and the mixture is shaped into a specified shape, dried, and then fired. The porosity of the porous structure is >30%, and the compressive strength is >15MPa. The water is natural water or tap water contained in the pores of the porous structure, as well as the water-based liquid.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0020] This invention provides a neutron shielding concrete containing artificial water-infused aggregate, wherein the components of the concrete are in the following mass ratio (kg / m³). 3 ):

[0021] The mixture comprises 900-1200 parts coarse aggregate, 600-800 parts serpentine fine aggregate, 200-260 parts cement, 80-120 parts mineral powder, 80-40 parts fly ash, 180-220 parts water, and 3-6 parts water-reducing agent; wherein the coarse aggregate is composed of artificial water-retaining aggregate and serpentine coarse aggregate, the mixing ratio can be arbitrary, and the particle size range is 3mm-40mm; the particle size range of the serpentine fine aggregate is 0.25mm-3mm. This artificial water-infused aggregate comprises a metal shell, a porous structure, and a water-based liquid. The metal shell is a sealed structure used to contain the porous structure. The porous structure is formed by mixing ceramsite raw material with 1%–10% by weight of powdered B4C or Gd2O3, wherein B4C accounts for 20%–80% of the total weight of the powder, the powder particle size is 10 micrometers, and the mixture is shaped into a specified form, dried, and then fired. The water-based liquid is natural water, tap water, or boric acid solution contained within the pores of the porous structure. This artificial water-infused aggregate is readily available, its preparation process is simple, and the production process can be highly industrialized. This allows for the production of a new type of concrete with superior moisture content, workability, fast neutron moderation capability, and thermal neutron absorption capability compared to existing concrete, meeting the needs of nuclear radiation, especially neutron shielding structures, in special nuclear facilities. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of artificial water-impregnated aggregate in neutron shielding concrete according to an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram showing the relationship between the thickness of the metal outer shell and the outer radius of the spherical shell in neutron shielding concrete containing artificial water-infused aggregate, according to an embodiment of the present invention.

[0024] In the picture:

[0025] 1-Metal shell, 2-Porous structure, 3-Water-based liquid. Detailed Implementation

[0026] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a neutron shielding concrete containing artificial water-impregnated aggregate and its preparation method. The advantages and features of the present invention will become clearer from the following description. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise proportions, used only to facilitate and clarify the illustration of the embodiments of the present invention. For ease of description, the terms "upper" and "lower" used below correspond to the upper and lower directions in the accompanying drawings, but this should not be construed as a limitation of the technical solution of the present invention.

[0027] Example 1

[0028] Neutron-shielding concrete containing artificial water-infused aggregate, wherein the components of the concrete are in the following mass ratios (kg / m³). 3 ):

[0029] The mixture comprises 900-1200 parts coarse aggregate, 600-800 parts serpentine fine aggregate, 200-260 parts cement, 80-120 parts mineral powder, 80-40 parts fly ash, 180-220 parts water, and 3-6 parts water-reducing agent; wherein the coarse aggregate is composed of artificial water-retaining aggregate and serpentine coarse aggregate, the mixing ratio can be arbitrary, and the particle size range is 3mm-40mm; the particle size range of the serpentine fine aggregate is 0.25mm-3mm.

[0030] This embodiment also provides a method for preparing neutron-shielded concrete containing artificial water-infused aggregate, the preparation method comprising the following steps:

[0031] Step S1: Mix and stir carbon nanotubes, water-reducing agent and water, and use ultrasound to promote the dispersion of carbon nanotubes to prepare a uniform suspension.

[0032] Step S2: Provide a mixed coarse aggregate made of artificial water-retaining aggregate, ordinary coarse aggregate and serpentine coarse aggregate. Add serpentine fine aggregate, cement, mineral powder and fly ash into the mixer and mix for 60 seconds.

[0033] Step S3: Add the suspension from step S1 and stir for 120–240 seconds.

[0034] The following is combined with Figure 1 and Figure 2 The present invention provides a detailed description of the structural composition of the neutron shielding concrete containing artificial water-infused aggregate.

[0035] Please continue to refer to this. Figure 1 and Figure 2A type of artificial water-based aggregate includes a metal shell 1, a porous structure 2, and water. The metal shell 1 is a sealed structure used to contain the porous structure 2. The porous structure 2 is made by mixing ceramsite raw material with 1% to 10% by weight of powdered B4C or Gd2O3, wherein the weight of B4C accounts for 20% to 80% of the total weight of the powder, the powder particle size is 10 micrometers, and the mixture is shaped into a specified shape, dried, and then fired. The water-based liquid 3 is natural water, tap water, or boric acid solution contained in the pores of the porous structure 2. The water-based liquid 3 is the main component for moderating fast neutrons generated by nuclear facilities.

[0036] In this embodiment, more preferably, the porosity of the porous structure 2 is >30%, and the cylinder compressive strength is >15MPa. The porous structure serves two purposes: firstly, it supports the spherical shell, preventing plastic deformation or buckling under normal working pressure; secondly, it accommodates moisture; and finally, the B and Gd elements can effectively absorb neutrons.

[0037] In this embodiment, more preferably, the ceramic particles are at least one type of ceramic particles selected from alumina particles, silicon carbide particles, and silicon nitride particles.

[0038] In this embodiment, more preferably, the metal outer shell is a metal spherical shell or other hollow, irregularly shaped closed structure. The metal outer shell is used to enclose the porous structure 2. Therefore, the shape of the metal outer shell is determined by the forming shape of the porous structure 2. The forming body of the porous structure 2 can be any structure. Therefore, the shape of the metal outer shell is not limited here, as long as it satisfies the effect of enclosing the porous structure 2 and completely sealing it.

[0039] In this embodiment, more preferably,

[0040] The radial stress of a spherical shell satisfies the classical formula in theoretical mechanics: The radial stress amplification factor is less than the yield stress of the spherical shell, i.e. Through formula conversion, the thickness of the spherical shell satisfies the following formula:

[0041] In the formula, σ l For the radial stress of the spherical shell, water is chosen as the water-based liquid, and the highest operating temperature under design conditions is 200℃. At this temperature, the critical boiling pressure of water is p = 1.55MPa. Alternatively, if a metallic spherical shell is selected, its yield stress σ... y =360MPa; R ranges from 1.5mm to 20mm; α is the amplification factor, ranging from 1.5 to 2.0. Taking a particle with an outer radius R = 10mm as an example, according to the formula... The calculated shell thickness t is at least 0.0323 mm; if the outer radius R of a particle is 20 mm, then the shell thickness t is at least 0.0646 mm. Therefore, if the metal material and the maximum operating temperature are determined, then p and σ... y Since both are constants, the thickness t of the metal spherical shell is linearly proportional to the outer radius R of the shell.

[0042] Please continue to refer to this. Figure 1 and Figure 2 This embodiment also provides a method for preparing artificial water-infused aggregate, which includes the following steps:

[0043] Step S1: Preparation of porous structure: Using natural clay, industrial solid waste, and engineering waste soil as basic raw materials, and adding 1% to 10% by weight of powdered B4C or Gd2O3, water and foaming agent are added to mix and form granules. The specific mass ratios are as follows:

[0044]

[0045] The firing temperature is controlled at 1300℃ for 3 hours. The particles are expanded by a foaming agent and the internal moisture is released during the firing at 1300℃ to obtain porous ceramsite. Finally, the ceramsite is sieved and classified according to its size, cylinder compressive strength and porosity to obtain a porous structure.

[0046] Step S2, Immersing the porous structure: The ceramsite prepared in step S1 is immersed in a water-based liquid. The open pores are the main channels for the ceramsite to absorb water. The liquid can enter the open pores through the action of surface tension and be transferred inside the ceramsite through the connectivity of the pores until the ceramsite absorbs the liquid to saturation. The volume of the water-based liquid can reach more than 25% of the total volume of the ceramsite.

[0047] Step S3, Freezing the porous structure: The ceramsite soaked in step S2 is grouped according to its size, and the grouped ceramsite is placed in a freezer to freeze the outer liquid and lock in the internal liquid.

[0048] Step S4, Coating with a metal shell: Place the frozen ceramic granules from step S3 in a high-temperature resistant net and immerse them in molten metal to coat the surface with a metal shell before removing them to obtain liquid-coated granules.

[0049] Step S5: Post-processing: The liquid-coated particles obtained in step S4 are subjected to post-processing, namely, the adhered artificial aggregates are cut and separated, the defects of the metal shell are reduced by tempering, and the obtained ceramsite is subjected to heating test and pressure test to screen qualified products, thereby obtaining artificial aggregates.

[0050] In this embodiment, more preferably, step S3 includes:

[0051] The size groups are separated by a radius difference of 0.5 mm; and the average radius R of each group is determined in advance through experiments. 平均 The freezing time T that allows the outer layer of liquid to freeze while the inner layer remains unfrozen. 冷冻 (R 平均 To prevent the entire liquid from freezing and cracking, thus damaging the porous structure, the unified freezing time for this group was set as T. 冷冻 (R 平均 ).

[0052] In this embodiment, more preferably, step S4 includes:

[0053] Based on the different size groups, the average radius R corresponding to each group is determined in advance through experiments. 平均 Minimum soaking time T for ceramsite 浸泡 (R 平均 Ensure that its surface is covered with a metal shell of thickness t; the uniform immersion time for this group is taken as T. 浸泡 (R 平均 ).

[0054] Specifically, three types of concrete test blocks were prepared for testing: artificial aggregate concrete (prepared using the aforementioned method, with an internal natural water volume of approximately 28%), ordinary concrete, and serpentine concrete. The corresponding mix proportions are shown in the table below. The particle size of the artificial coarse aggregate, ordinary crushed stone, and serpentine was 5-10 mm in a continuous gradation. The fineness modulus of the artificial fine aggregate, river sand, and serpentine sand was controlled at approximately 2.3. PO 52.5 silicate cement was used, and the solids content of the water-reducing agent was 28%.

[0055]

[0056] Concrete was molded into cylindrical specimens with a diameter of 6 cm and a height of 4 cm, and tested after standard curing for 28 days. Three types of concrete were irradiated using an electron accelerator with neutrons at energies of approximately 0.01 eV, 1 eV, and 100 eV. The neutron shielding capability was determined by recording the flux of neutrons after penetrating the concrete. Each energy level was irradiated for approximately 5 hours, and the neutron emission flux from the electron accelerator was approximately 100,000 ns.

[0057] The neutron flux data obtained after penetrating concrete are shown in the table below:

[0058]

[0059]

[0060] As can be seen from the table, the neutron shielding ability of artificial aggregate concrete is better than that of ordinary concrete and serpentine concrete at three energies: 0.01eV, 1eV, and 100eV. The neutron shielding rate of artificial aggregate concrete can be increased by about 25% and 10% compared with that of ordinary concrete and serpentine concrete, respectively.

[0061] The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. The above embodiments only illustrate several implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A neutron-shielding concrete containing artificial water-infused aggregate, characterized in that, The components of the concrete are specified in kg / m³. 3 The mass ratio is: The mixture comprises 900-1200 parts coarse aggregate, 600-800 parts serpentine fine aggregate, 200-260 parts cement, 80-120 parts mineral powder, 80-40 parts fly ash, 0.5-1.0 parts carbon nanotubes, 180-220 parts water, and 3-6 parts water-reducing agent. The coarse aggregate is composed of artificial water-impregnated aggregate, ordinary coarse aggregate, and serpentine coarse aggregate, with the artificial water-impregnated aggregate comprising >50% and having a particle size range of 3-40 mm. The serpentine fine aggregate has a particle size range of 0.25 mm-3 mm. The artificial water-infused aggregate comprises a metal shell, a porous structure, and a water-based liquid. The metal shell is a sealed structure used to contain the porous structure. The porous structure is formed by mixing ceramsite raw material with 1% to 10% by weight of powdered B4C or Gd2O3, the powder having a particle size of 10 micrometers, shaping it into a specified shape, drying the resulting molded body, and then firing it. The water-based liquid is natural water, tap water, or boric acid solution contained in the pores of the porous structure.

2. The neutron shielding concrete containing artificial water-impregnated aggregate according to claim 1, characterized in that, The porosity of the porous structure is >30%, and the cylinder compressive strength is >10MPa.

3. The neutron shielding concrete containing artificial water-impregnated aggregate according to claim 1, characterized in that, The metal outer shell is a metal spherical shell or other hollow, irregularly shaped closed structure, and the metal is made of stainless steel.

4. The neutron shielding concrete containing artificial water-impregnated aggregate according to claim 3, characterized in that, The outer radius of the metal spherical shell is R, and the thickness is t, where the value of R ranges from 1.5 mm to 20 mm. , In the formula, α is the safety factor, which takes a value of 1.5~2.0; p=1.55 MPa is the critical boiling pressure of water at 200℃; σ y =360 MPa is the yield stress of the metal material.

5. The method for preparing neutron-shielded concrete containing artificial water-impregnated aggregate according to claim 1, characterized in that, Includes the following steps: Step S1: Mix and stir carbon nanotubes, water-reducing agent and water, and use ultrasound to promote the dispersion of carbon nanotubes to prepare a uniform suspension. Step S2: Provide a mixed coarse aggregate made of artificial water-retaining aggregate, ordinary coarse aggregate and serpentine coarse aggregate. Add serpentine fine aggregate, cement, mineral powder and fly ash into the mixer and mix for 60 seconds. Step S3: Add the suspension from step S1 and stir for 120-240 seconds.

6. The preparation method according to claim 5, characterized in that, The artificial water-infused aggregate comprises a metal shell, a porous structure, and a water-based liquid. The metal shell is a sealed structure used to contain the porous structure. The porous structure is formed by mixing ceramsite raw material with 1% to 10% by weight of powdered B4C or Gd2O3, the powder having a particle size of 10 micrometers, shaping it into a specified shape, drying the resulting molded body, and then firing it. The porosity of the porous structure is >30%, and the cylinder compressive strength is >15MPa. The water is natural water or tap water contained in the pores of the porous structure.

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