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INVENTION
Russian Federation Patent RU2194316

METHOD FOR PRODUCING A RADIATION-PROTECTIVE CONCRETE

METHOD FOR PRODUCING A RADIATION-PROTECTIVE CONCRETE

Name of the inventor: Sviridov NV .; Vorontsov VV .; Gevirts VB .; Guskov VD .; Kovalenko MG .; Kryukov VY .; Trofimov NA .; Khodasevich KB
The name of the patentee: Federal State Unitary Enterprise "KB SM"
Address for correspondence: 194100, St. Petersburg, Federal State Unitary Enterprise "KB SM"
Starting date of the patent: 2002.03.10

The invention relates to the construction, in particular to the manufacturing technology of radiation-shielding concrete, used mainly for the production of reinforced concrete (metallobetonnyh) containers for the storage and / or transportation of radioactive materials. The technical result - a reduction in the concrete manifestation of an array of negative factors affecting the radiation-chemical safety of operation of such structures as metallobetonnye containers. In the method of manufacturing a radiation shielding concrete, comprising preparing a concrete mix with preparation included in the composition of its components aggregate of scale in preparing aggregate of scale subjected to passivation, which pre-mixed with water and then wet aggregate of dross was placed in a furnace where maintained in a predetermined mode, said filler before passivation enriched by washing in water.

DESCRIPTION OF THE INVENTION

The invention relates to the construction, in particular, to the manufacturing techniques of radiation-shielding concrete, used mainly for the production of reinforced concrete (metallobetonnyh) containers for the storage and / or transportation of radioactive materials.

Effective use of concrete as a filler metal structures housing metallobetonnogo closed container for long term storage and / or transportation, for example, spent nuclear fuel (SNF), due to the need to simultaneously ensure high mechanical and radiation-protective properties of concrete. This is achieved, for example, by using as a filler in the preparation of concrete dross, which is selected from the smelter by different processes.

In operation metallobetonnogo container loaded SNF in the concrete which fills the cavity between the inner and outer metallic shells metallobetonnogo container under the influence of radiation (mainly radiation) and heat flux from the originate SNF various kinds of processes, accompanied by evolution of hydrogen and an increase in pressure within the internal voids in the concrete and hermetically sealed cavity respectively between the outer container and the inner metallic shell.

These processes include:

1. Thermochemical corrosion "pure" (non-oxidized) iron available in the scale, which flows rapidly with increasing temperature of the concrete.

2. Electrochemical corrosion is determined by the flow of concrete through the conductive medium of electric current between the two metals with different electrochemical potentials.

The conductivity of the concrete in this case is defined as the presence in the pores of the concrete-free and bound water adsorption and ionization of the gas mixture then exposed concrete SNF radiation.

3. Concrete radiolysis of water, including chemically bound, under the influence of radiation SNF.

Activity thermochemical and electrochemical reactions of metal corrosion and hydrogen respectively when the selection of these reactions depends on the number of "clean" (non-oxidized) iron in the scale and quantity graded scale (most reactive fraction).

When operating metallobetonnogo container loaded SNF, the above processes can lead to such negative phenomena as:

1. Excessive increase in pressure in the pores of the concrete and the filler metal in the cavity between the outer and inner shells metallobetonnogo container.

2. Electrochemical corrosion in contact with a concrete filler enclosing sealing metal structures made from steel (such as stainless) having compared to the electrochemical potential of the other dross.

In this case, if the operational rules of the SNF storage technology may provide periodic discharge pressure of the closed cavities metallobetonnogo container containing concrete filler, and the gassing intensity only determines the frequency or duration of the machining operation, the electrochemical corrosion processes enclosing concrete sealing metal are out of control.

Depressurization container enclosing structure due to corrosion of the metal can lead to failure of radionuclide from the inner space of the container during long-term storage of spent nuclear fuel.

Thus, the reduction in the intensity of the electrochemical corrosion process of metal fencing concrete task is no less important than the decline in gas production rate, and a direct impact on environmental safety of spent fuel storage.

An essential condition for improving the reliability metallobetonnyh containers, which are characterized by placing concrete in an array hermetic cavity between the outer and inner shells of metal containers, is to minimize the rate of gas release and pressure of the gas phase in the pores of the concrete and steel structures in a closed cavity.

Known methods of making radiation-shielding concrete, which are implemented in the production of reinforced concrete (metallobetonnyh) containers. Known methods include the preparation of concrete, composed of components includes a filler scale. The prepared concrete mixture is placed in the design of reinforced concrete (metallobetonnogo) container and kept in a given mode. When this is placed inside the concrete means for removing gases from the closed structure surrounding cavities in the container space.

For example, it is known concrete containers for storage and transport of spent fuel elements of a nuclear reactor assemblies according to the patent RU 2082232 (IPC 6 G 21 F 5/008, 1994). The concrete design of the container is applied a composition comprising as an aggregate scale metallurgical wastes. For the removal of concrete gas and water vapor in the container, a system of perforated vents disposed about the inner metal shell container. In the upper part of the container in the combined vent pipe manifold assembly, which, during the drying of concrete through the channel in the forged upper ring of the container body is connected by means of the process valve to atmosphere. After completion of drying, said channel is closed safety diaphragm rupture.

and is known a container for transport and / or storage of spent nuclear fuel according to the patent RU 2089948 (IPC 6 G 21 F 5/008, 1995). In a container comprising inner and outer cylindrical shell with end plates, between which the cavity is filled with heavy concrete, concrete aggregate accommodated inside pipelines connected annular collector. Gas and collector are in the form of metal wires. Collector communicates with the outside derived channel overlapped vodorodopronitsaemoy membrane. When operating the hydrogen container which is formed in the concrete mass as a result of reactions radiolysis of water and metal corrosion due to diffusion concrete reaches gazoprovodyaschih metal cables and through the collector reaches vodorodopronitsaemoy membrane. Diffusing through the membrane, the hydrogen comes from the container into the surrounding space of the container.

However, known solutions, providing a pressure release hydrogen concrete filled cavities closed container, hermetic container suggest reduction properties and a consequent reduction of its environmental safety. Furthermore, the known solutions by providing gas pressure relief, do not solve the problem of reducing the intensity of gassing process in concrete.

The closest to the technical nature of the proposed method is a method of manufacturing a radiation-shielding concrete, comprising the preparation of a concrete mix with preparation is part of the components of the aggregate scale (patent RU 2100304, IPC 6 C 04 B 28/00, G 21 F 5 / 00, 1/04, 1996). Concrete mixture comprises the following components: fine and coarse aggregate of scale, cement, superplasticizer C-3 and the mixing water. Scale advance, before the application in the case is treated for 20-40 s in a ball mill, then the mixture is removed from the treated grain size from 0 to 0.16 mm, and the remaining mass scale scatter on fractions 10-20, 5-10, 1,25-5, 0,63-1,25, 0,16-0,63 mm. During processing in a ball mill scale is destroyed inclusions and weak contacts of large grains, and a foreign matter. When plating weak grain are removed together with grains 0-0,16 mm. In an embodiment of the prepared concrete mixture is placed in the design metallobetonnogo container for transport or storage of spent nuclear fuel.

The well-known method of manufacturing a radiation-shielding concrete provides a sufficiently high strength concrete, which is achieved through the use of the most durable of the varieties of the scale - scale machine scarfing blooms, slabs and other preparations, a low water-cement ratio of the concrete mix, the optimal selection of the weight ratio of the aggregates in concrete and pre-preparation aggregate of scale.

However, the known method of manufacturing a radiation-shielding involves the use of concrete for making the concrete mix sufficiently large amount of dross filler, resulting in the presence of a large amount of concrete a "clean" (non-oxidized) iron, have an adverse effect on the intensity of gas evolution processes in concrete.

The object of the invention to provide a method of manufacturing a radiation-shielding concrete, providing a reduction in the concrete manifestation of an array of negative factors affecting the radiation-chemical safety of operation of such structures as metallobetonnye containers.

This object is achieved by the fact that in the known method of manufacturing a radiation shielding concrete, comprising preparing a concrete mix with preparation included in the composition of its components aggregate of scale, according to the invention in the preparation of the aggregate of scale subjected passivation, which is stirred beforehand with water, then wet scale of filler is placed in a furnace where maintained in a predetermined mode.

At this scale of filler to enrich passivated by rinsing in water.

The technical result of using the invention is that due to passivation reduces the number of "clean" (non-oxidized) of iron on the surface used in the preparation of concrete aggregate of the scale, whereby the operation of radiation-shielding concrete decreases the intensity of processes of thermochemical and electrochemical corrosion aggregate of dross , electrochemical corrosion of metal and concrete fencing, respectively reduced the gassing in concrete. All this, ultimately, improves the reliability of structures, which are characterized by an array of concrete placement in sealed cavities, for example, structures such as reinforced concrete (metallobetonnye) containers for spent nuclear fuel.

In an embodiment, the inventive method is used for the manufacture of radiation shielding concrete, such as concrete (metallobetonnyh) containers for the transportation and / or storage of spent nuclear fuel.

The technology of the manufacturing method of radiation-shielding concrete is as follows. The concrete mix is ​​prepared in a mixer with forced mixing. Thus drum mixer was charged with the components of the concrete mix not more than 60% of its volume, due to the relatively high density of the concrete mixture comprising aggregates of scale. In a concrete embodiment, the mixture comprises the following components: small and large scale filling of cement, a superplasticizer, for example, based on the sodium salt of a condensation product of naphthalenesulfonic acid and formaldehyde-3 and the mixing water. With this in other embodiments, the concrete mix may also include other components. For example, the concrete mix may further contain as a filler fraction of the cast iron or steel and retarder mixture. The desired scale is selected from the smelter by different processes. Scale to use in the case in the standard scatter fraction, for example, 10-20, 5-10, 1.25-2.5, 0,16-1,25 mm, remove the grain larger 20 mm and foreign matter.

In an embodiment of the previously prepared filler scale enriched by washing in water. This minimizes the number of the most reactive graded scale.

Thereafter aggregate of scale is subjected to passivation. In an embodiment of the dross filler passivation is as follows. First, filler are mixed with water in the mixer or in the washing machine. When this ratio is maintained aggregate of scale and water, respectively, by weight of 1: 3. Then the water is drained and a wet aggregate of scale in suitable containers placed in a furnace where temperature is maintained 100-200 o C for 18-24 hours, then dried at a given time to time at a temperature of 800 o C to constant weight. Time mode is determined by the size scale faction. As a result of this drying dross burnt organic contaminants which can be a source of outgassing in the concrete under the influence of radiation and thermal action.

Thereafter, the concrete mix with a given sequence prepared components are fed into the mixer with forced mixing and stirring with an exposure time slots.

Then, the prepared concrete mixture is placed in the design of reinforced concrete (metallobetonnogo) container and kept in a given mode.

Due to passivation of the reduced amount of "clean" (non-oxidized) of iron on the surface used in the preparation of concrete aggregate of the dross, thereby reducing the intensity of the process of thermochemical and electrochemical corrosion aggregate of scale, galvanic corrosion enclosing concrete metal in contact with a concrete filler, and correspondingly reduced the gassing in concrete when exposed to radiation, and exposure to heat during the operation of concrete (metallobetonnyh) containers for the storage and / or transportation of spent nuclear fuel.

Thus, due to the peculiarities of the proposed method of manufacturing a radiation-shielding concrete reduces the activity occurring within the concrete array of processes accompanied by the release of hydrogen and increase the pressure in the inner pores of the concrete, and corrosion resistance of the enclosing concrete steel while maintaining the sealing properties of the latter, which improves the reliability and environmental safety of structures, which are characterized by an array of concrete placement in sealed cavities, for example, structures such as reinforced concrete (metallobetonnye) containers for the transportation and / or storage of radioactive materials.

CLAIM

1. A method of manufacturing a radiation shielding concrete comprising forming concrete with preparation is part of the components of the dross filler, wherein the filler in the preparation of dross subjected passivation, which pre-mixed with water and then wet aggregate of dross placed in an oven where a predetermined mode is maintained.

2. A method according to claim 1, characterized in that said aggregate to enrich passivated by rinsing in water.

print version
Publication date 18.01.2007gg