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INVENTION
Patent of the Russian Federation RU2179538

METHOD OF MANUFACTURE OF RADIATION PROTECTIVE CONCRETE

The name of the inventor: Sviridov NV; Vorontsov VV; Guskov V.D .; Gevirtz VB; Kovalenko M.G .; V. Kryukov; Khodasevich K.B.
The name of the patent holder: Federal State Unitary Enterprise "Design Bureau of Special Machine Building"
Address for correspondence:
Date of commencement of the patent: 2000.04.05

The invention relates to construction, in particular to technologies for manufacturing radiation-protective concrete used for the manufacture of metal-concrete containers intended for the storage and / or transportation of radioactive materials. The technical result is an increase in radiation and chemical safety in the operation of structures such as metal-concrete containers. The method of manufacturing radiation-protective concrete, which includes the preparation of a concrete mixture from small and coarse aggregate from scale with the preliminary preparation of the latter with separation into fractions, cement, superplasticizer and mixing water, the laying of the concrete mixture, its compaction and hardening, with the holding of temperature and time modes, That the prepared and fractionated aggregate from the scale is enriched, then it is subjected to passivation, after which the prepared components of the concrete mix with a predetermined sequence are fed into the mixer with forced stirring and mixed with time delay, the concrete mix inhibitor is fed to the concrete mixer, then The prepared concrete mixture is laid in a construction and maintained in the set mode. In the case of passivation, the aggregate is mixed with water in the washing unit while maintaining the ratio of the aggregate from scale and water by 1: 3, respectively, then draining the water and the wet aggregate from the scale is placed in an oven where, at a temperature of 100-200 ^° C., 18-24 hours, after which it is dried at a predetermined time regime to 800 ^° C. to constant weight, when feeding the components of the concrete mixture to the concrete mixer, the aggregate is first fed from the scale, followed by stirring for 20-30 seconds, then 30% Water of mixing and 30% of the mass of the superplasticizer, the mixture is stirred for 20-30 seconds, after which cement is supplied, 50% of the mass of the mixing water, the remaining mass of the superplasticizer and the retarder for setting the concrete mix, the mixture is stirred for 40-60 seconds, Then the remaining mass of mixing water is supplied and the mixture is stirred for 20-30 seconds, with the concrete mixer drum being loaded with components of the concrete mixture no more than 60% of its volume.

DESCRIPTION OF THE INVENTION

The invention relates to construction, in particular to technologies for manufacturing radiation-protective concrete, used primarily for the manufacture of reinforced concrete (metal-concrete) containers intended for the storage and / or transportation of radioactive materials.

Effective use of concrete as a filler of closed steel structures of a housing of a concrete container intended for long-term storage and / or transportation, for example spent nuclear fuel (SNF), is associated with the need for simultaneous provision of high mechanical and radiation protective properties of concrete. This is achieved, for example, by using as a filler in the preparation of a concrete slag, which is selected in metallurgical production from various technological processes.

When operating a metal-concrete container loaded with SNF in a concrete filling the cavity between the metallic outer and inner shells of a metal-concrete container, under the influence of radiation (mainly -radiation) and heat flow from the SNF side, various processes occur, accompanied by the evolution of hydrogen and increased pressure in the internal pores of concrete and, respectively, in the hermetic cavity between the outer and inner metal shells of the container.

Such processes include:

1. Thermochemical corrosion of "pure" (unoxidized) iron, present in scale, which intensively proceeds with increasing temperature of concrete.

2. Electrochemical corrosion, which is determined by the flow through an electrically conductive concrete medium between metals with different electrochemical potentials.

The conductivity of concrete in the case under consideration is determined both by the presence of free and adsorption-bound water in the pores of the concrete and by the ionization of the gas mixture of the concrete pores under the influence of SNF radiation.

3. Radiolysis of concrete water, including chemically bound, under the influence of radiation from SNF.

The activity of the reactions of thermochemical and electrochemical corrosion of the metal and, correspondingly, the evolution of hydrogen in these reactions depends on the amount of "pure" (unoxidized) iron in the scale and the number of fine and pulverized fractions of scale (the most chemically active fractions).

An essential condition for improving the reliability of concrete containers, which are characterized by the placement of a concrete massif in the hermetic cavity between the outer and inner metal shells of the container, is to minimize the intensity of gas evolution and pressure of the gas phase in the pores of concrete and in enclosed cavities of metal structures.

There are known methods of manufacturing radiation-protective concrete, which are realized in the manufacture of reinforced concrete (metal-concrete) containers. Known methods include the preparation of a concrete mixture, the components of which include a scale aggregate. The prepared concrete mixture is laid in the construction of a reinforced concrete (metal-concrete) container and maintained in the prescribed mode. At the same time, inside the concrete, means are provided for the removal of gases from the closed cavities of the structure to the surrounding space.

For example, a reinforced concrete container for storing and transporting spent fuel assemblies of a nuclear reactor according to RU 2082232 (MPC ⁶ G 21 F 5/008, 1994) is known. In the construction of the container, a concrete composition is used, which includes as a filler the scale of the waste of metallurgical production. To remove from the concrete gases and water vapor in the container, a system of perforated gas pipes is provided, located near the inner metal shell of the container. At the top of the container, the vapor pipes are combined into a collector manifold, which, during the drying of concrete through a channel in the forged upper ring of the container body, is connected by a process valve to the atmosphere. After completion of drying, the said channel is closed by a bursting safety membrane.

And a container for SNF transportation and / or storage is known under RU 2089948 (IPC ⁶ G 21 F 5/008, 1995). In a known container containing inner and outer cylindrical shells with bottoms, the cavity between which is filled with heavy concrete, gas pipelines connected by a ring collector are located inside the concrete aggregate. Gas pipelines and the collector are made in the form of metal cables. The collector is communicated with an outwardly formed channel blocked by a hydrogen permeable membrane. When the container is operated, hydrogen, which is formed in the concrete massif as a result of the reactions of water radiolysis and metal corrosion, through diffusion through concrete reaches the gas-conducting metal cables and then through the collector reaches the hydrogen permeable membrane. Diffunding through the membrane, hydrogen leaves the container into the container surrounding the container.

However, the known solutions that ensure the release of hydrogen pressure in concrete filled container cavities suggest a reduction in the hermetic properties of the container and, consequently, a reduction in its environmental safety. In addition, the known solutions, ensuring the release of gas pressure, do not solve the problem of reducing the intensity of gas evolution in concrete.

The closest in technical essence to the proposed method is the method of manufacturing radiation-protective concrete, which includes the preparation of a concrete mixture from small and coarse aggregate from scale with preliminary preparation of the latter with separation into fractions, cement, superplasticizer and mixing water (patent RU 2100304, IPC ⁶ C 04 B 28/00, G 21 F 5/00, 1/04, 1996). The known method involves laying a concrete mixture in the construction of a concrete-concrete container, sealing it and hardening it with an exposure of time intervals. Ocalinum is preliminarily treated prior to application in the case for 20-40 seconds in a ball mill, then grains from 0 to 0.16 mm are removed from the treated mixture, and the remaining scale mass is dispersed into fractions: 10-20, 5-10, 1.25-5, 0.63-1.25, 0.16-0.63 mm. During the processing of scale in a ball mill, weak inclusions and contacts of large grains are destroyed, as well as foreign impurities. During sieving, weak grains are removed together with grains of 0-0.16 mm.

The known method of manufacturing radiation-protective concrete provides a sufficiently high strength of concrete, which is achieved due to the use of the most durable of the scale types - scale of machine fire stripping of blooms, slabs and other blanks, low water-cement ratio of concrete mix, optimal selection of the mass ratio of aggregates in concrete and preliminary preparation Aggregate from scale.

However, the known method of manufacturing radiation-protective concrete involves the use of a large amount of aggregate from the scale for the preparation of a concrete mixture, which results in the presence of a large amount of "pure" (unoxidized) iron in the concrete mixture, which has an undesirable effect on the intensity of gas evolution in concrete.

It is an object of the present invention to provide a method for manufacturing radiation-protective concrete that reduces the manifestation in a concrete massif of negative factors affecting the radiation-chemical safety of operation of structures such as metal-concrete containers.

This object is achieved due to the fact that in the known method of manufacturing radiation-protective concrete comprising the preparation of a concrete mixture from a fine and coarse aggregate from scale with preliminary preparation of the latter with separation into fractions, cement, superplasticizer and mixing water, laying of the concrete mixture, Hardening with aging of temperature and time modes, according to the invention, the aggregate prepared from the scale is enriched and then subjected to passivation. After that, the prepared components of the concrete mix with the given sequence are fed into the mixer with forced stirring and mixed with the holding of time intervals. At the same time, a concrete retarder is applied to the concrete mixer. Then the prepared concrete mix is ​​put in a design and maintained in the set mode.

When the aggregate is passivated from the scale, the aggregate is first mixed with water in the washing unit. In this case, the ratio of the aggregate from the scale and the water is 1: 3 by weight, respectively. Then, the water is drained and the wet aggregate is placed in an oven where, at a temperature of 100-200 ^° C., it is held for 18-24 hours, after which it is dried for a given time mode at Temperature up to 800 ^° C to constant weight.

When feeding the components of the concrete mix to the concrete mixer, the aggregate from the scale is first fed. After that, stirring is carried out for 20-30 seconds. Then 30% of the mass of the mixing water and 30% of the weight of the superplasticizer are fed. Mix the mixture for 20-30 seconds. After that, cement is supplied, 50% of the mass of the mixing water, the remaining mass of the plasticizer and the retarder for setting the concrete mixture. Mix the mixture for 40-60 seconds. Then, the remaining mass of mixing water is supplied and the mixture is stirred for 20-30 seconds.

At the same time, the drum of the concrete mixer is loaded with components of the concrete mixture no more than 60% of its volume.

In an embodiment of the invention, the inventive method is used for manufacturing radiation-protective concrete, for example, for reinforced concrete (metal-concrete) containers intended for storage and / or transportation of SNF.

The technology of the method for manufacturing radiation-protective concrete is as follows. The concrete mixture is prepared in a mixer with forced stirring. In this case, the mixer drum is loaded with concrete mixture components by no more than 60% of its volume, which is due to a sufficiently high density of the concrete mix. In an embodiment of the invention, the concrete mixture comprises the following components: fine and coarse scale aggregate, cement, mixing water, superplasticizer, for example based on the sodium salt of the condensation product of naphthalenesulfonic acid and formaldehyde C-3 and a retarder for setting a concrete mixture, for example nitrilotrimethylene phosphonic acid. However, in other embodiments, the concrete mixture may include other components. For example, in order to increase the density and strength of concrete, the concrete mix can additionally include a cast iron or steel shot instead of a portion of the fine aggregate. The required scale is chosen in metallurgical production from various technological processes. Ocalin prior to use in the case is dispersed into standard fractions, for example, a large aggregate of fractions of 10-20, 5-10 mm and fine filler of fractions of 1.25-2.5, 0.16-1.25 mm, remove grains larger than 20 mm and Foreign inclusions.

The pre-prepared and fractionated aggregate from the scale is enriched by washing in water. This makes it possible to minimize the number of the most chemically active fine and dust scale fractions of scale.

After that, the aggregate from the scale is passivated. In an embodiment of the invention, the passivation of the aggregate from the scale is as follows. First, the aggregate is mixed with water in the washing unit. In this case, the ratio of the aggregate from the scale and water is kept to 1: 3 by weight, respectively. Then, the water is drained and the wet aggregate from the scale in the respective containers is placed in an oven where, at a temperature of 100-200 ^° C, it is held for 18-24 hours, after which Is dried at a given time mode at a temperature of up to 800 ^° C. to constant weight. The time regime is determined by the size of the scale fraction. As a result of such drying, organic contaminants are burned out of the scale, which can be a source of gas emission in concrete under the influence of radiation and thermal action.

After that, the prepared components of the concrete mix with the given sequence are fed into the mixer with forced stirring and mixed with the holding of time intervals. In the embodiment, when feeding the components of the concrete mixture to the concrete mixer, the aggregate is first fed from the scale, followed by stirring for 20-30 seconds. Then 30% of the mass of the mixing water and 30% of the mass of the superplasticizer C-3 are fed. The mixture is stirred for 20-30 seconds, after which cement is supplied, 50% of the mass of the mixing water, the remaining mass of the superplasticizer C-3 and the retarder for setting the concrete mixture. Mix the mixture for 40-60 seconds. Then, the remaining mass of mixing water is supplied and the mixture is stirred for 20-30 seconds. The total mixing time for the concrete mix is ​​3-4 minutes.

Then the prepared concrete mixture is laid in the construction of reinforced concrete (metal-concrete) container and maintained in the prescribed mode.

Due to the passivation, the amount of "pure" (unoxidized) iron on the surface of the aggregate used in the preparation of the concrete mixture from the scale is reduced, as a result of which the intensity of gas formation in the concrete is reduced under the influence of radiation and thermal action during the operation of reinforced concrete containers intended for storage and / Or SNF transportation.

Thus, due to the features of the design, the proposed method for manufacturing radiation-protective concrete ensures a reduction in the activity of processes occurring inside the concrete massif, accompanied by the release of hydrogen and increased pressure in the internal pores of concrete, which increases the reliability and environmental safety of structures for which the placement of a concrete massif Hermetic cavities, for example, structures such as reinforced concrete (metal-concrete) containers for the transport and / or storage of radioactive materials.

CLAIM

1. A method for the production of radiation-protective concrete, comprising the preparation of a concrete mixture from a fine and coarse aggregate from scale with a preliminary preparation of the latter with separation into fractions, cement, superplasticizer and mixing water, laying of the concrete mixture, sealing and hardening with time and temperature , Characterized in that the prepared and fractionated aggregate from the scale is enriched, then it is subjected to passivation, after which the prepared components of the concrete mixture with a predetermined sequence are fed to the mixer with forced stirring and mixed with aging of the time intervals, and a concrete retarder is supplied to the concrete mixer Mixture, then the prepared concrete mixture is laid in a structure and maintained in a predetermined mode.

2. A process according to claim 1, characterized in that, when passivated, the aggregate is mixed with water in the washing unit while maintaining the ratio of the aggregate from scale and water by 1: 3, then draining the water and the wet aggregate from the scale is placed in an oven, Where it is held at a temperature of 100-200 ^° C for 18-24 hours, after which it is dried at a given time mode to 800 ^° C to constant weight.

3. A method according to claim 1, characterized in that, when feeding the components of the concrete mixture, the aggregate is first fed from the scale, followed by stirring for 20-30 seconds, then 30% of the weight of the mixing water and 30% of the weight of the superplasticizer are fed, Mixing the mixture for 20-30 seconds, after which cement is supplied, 50% of the mass of the mixing water, the remaining mass of the superplasticizer and the retarder for setting the concrete mix, the mixture is stirred for 40-60 seconds, then the remaining mass of the mixing water is supplied and the mixture is stirred 20-30 sec.

4. A method according to claim 1, characterized in that the concrete mixer drum is loaded with components of the concrete mixture by no more than 60% of its volume.

print version
Date of publication 01/18/2007

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