RU171956U1 - BIMETALLIC BODY CASE - Google Patents

Abstract

The device relates to nuclear energy, and in particular to distance devices that house fuel assemblies with spent nuclear fuel during their transportation and temporary storage in transport packaging units (TUK). The bimetal cover for TUK includes a monolithic case in which channels for placement fuel assemblies are formed by metal pipes fixedly connected to the monolithic casing due to shrinkage occurring during the crystallization of molten iron during the manufacture of monolithic hulls.

Description

The device relates to nuclear energy, and in particular to distance devices that house fuel assemblies with spent nuclear fuel during their transportation and temporary storage in transport and packaging units (TUKs).

Known case for the placement and storage of spent fuel assemblies of the VVER-1000 reactor (Description of the invention to patent RU 2593388, priority 04.08.2015, published 08/10/2016, bull. No. 22), containing a central pipe, spacer grids with hexagonal pipes. Remote lattices with hexagonal pipes are made in the form of sections fastened together. Each section is made of aluminum alloy and consists of a central pipe, two spacer grids with hexagonal holes. Hexagonal pipes are placed in the holes. Pipes have internal hexagonal grooves at the ends. Hexagonal guides made of corrosion-resistant steel are installed in the grooves. The sections are mounted on a base consisting of a distance support with holes. On the axis of the holes on the outside are installed clamping devices. The support pipe is made of corrosion-resistant steel and has an adapter for a load gripping device.

A disadvantage of the well-known cover for placement and storage of spent fuel assemblies of the VVER-1000 reactor is the low manufacturability of the structure due to the many used structural elements, the complexity of their manufacture and the need to ensure high accuracy of their installation. Another disadvantage of the known cover for the placement and storage of spent fuel assemblies of the VVER-1000 reactor is its high cost, associated with the complexity of manufacture.

Known transport and packaging for spent fuel assemblies of nuclear reactors (Description of the invention to patent RU 2463677, priority 04/22/2011, published 10/10/2012, bull. No. 28), including a cover and a container consisting of a housing made with a sealed overlap of the internal cavity of the container . A cover is installed in the cavity of the container. The cover in the cavity of the container is installed with a predetermined radial clearance with the possibility of the formation of heat-conducting contact between the outer surface of the cover and the inner surface of the container body in the loaded state of the latter when exposed to heat from the spent fuel assemblies. The cover is made of stainless steel and includes the upper and lower spacer grids, to which hexagonal pipes are tightly welded to accommodate spent fuel assemblies, and a lining is installed along the perimeter of the cover with the formation of a hermetic annular space, which is filled with a heat-conducting material (heat-conducting composition), and the outer the surface of the hexagonal tubes is coated with a self-fluxing boron-containing alloy.

A disadvantage of the known transport and packaging kit for spent fuel assemblies of nuclear reactors is the high complexity of the work, due to the complexity of the design of the cover, namely the need to install the upper and lower spacer grids, the need for welding to attach hexagonal pipes to them, which serve to accommodate the fuel assemblies and provide with a heat-conducting contact between the housing and the spacer grid. The disadvantages include the high cost of construction, due to the need to use expensive stainless steel and the complexity of the assembly of the device.

The closest and taken as a prototype is the well-known design of a transport and packaging set for transporting and storing spent nuclear fuel (Description of a utility model for patent RU 75496, priority 02.27.2008, published 10.08.2008, bulletin No. 22), including made of ductile iron with spherical graphite housing, inner and outer covers, case and dampers. The housing has longitudinal channels filled with heat-resistant polyethylene. To increase the heat transfer surface between the cover, the container body and the surrounding air, the outer surface of the container body has annular turned ribs, and the inner surface of the container body and the outer surface of the cover have conjugated cooling fins, which intensify the heat removal from the spent fuel assemblies placed in the container cover to container body and further into the environment. The cover is made of monolithic metal with channels for installing fuel assemblies. In this case, cooling fins are made on the outer surface of the cover, mating with cooling fins on the inner surface of the housing.

A disadvantage of the design of the known transport packaging for transportation and storage of spent nuclear fuel is the low adaptability of the cover design, due to the need to manufacture, install and remove the rods forming the channels for installing the fuel assemblies in a monolithic case during its manufacture, as well as the need for accurate machining of the channels for installation of fuel assemblies. The disadvantages also include the high cost of the structure, due to the high complexity of the work on its manufacture.

The technical result of the proposed bimetallic cover for TUK is to increase manufacturability and reduce costs.

The technical result is achieved in that in a bimetallic cover for TUK, which includes a monolithic body with channels for installing fuel assemblies, the channels are framed by metal pipes that are fixedly fixed in the monolithic body due to shrinkage that occurs during the crystallization of cast iron melt during the manufacture of casting of the monolithic body

In FIG. 1 shows a top view of a bimetallic cover for TUK.

In FIG. 2 shows a section A-A of a bimetallic cover for TUK.

In FIG. 3 shows the remote element I from section AA of a bimetallic cover for TUK.

In FIG. 4 is a cross-sectional view of a container of a packaging unit.

The proposed bimetallic cover for TUK includes a monolithic housing 1 with metal pipes 2 framing the channels 3 for the installation of fuel assemblies. In the manufacture of casting a monolithic body 1 of a bimetallic cover for TUKs, metal rods 2 are used as rods forming channels 3 in the casting of a monolithic body, which are used to house the fuel assemblies, which, when manufacturing a casting of a monolithic body 1, are fixedly connected due to shrinkage during crystallization molten cast iron body castings. Bottom to the bimetallic cover for TUK is attached by a mechanical joint, for example, by a welded joint, a support plate 4 with holes. This support bottom 4 serves as a support for fuel assemblies loaded into the channels 3 of the housing 1 of the bimetal cover for TUK. A bottom 5 is mounted under the support bottom 4, so that a free internal space is provided between the support bottom 4 and the bottom 5. A protective coating 7 is applied to the upper end of the bimetallic cover for the TUK, which is resistant to decontamination solutions.

In order to impart high radiation-protective properties to a bimetallic cover for TUK, pipes made of boron-containing metal should be used as metal pipes 2, and in the manufacture of a monolithic body 1, high-strength spheroidal graphite cast iron (VChShG) should be used.

Implemented by the proposed device as follows.

Metal tubes 2 are installed in the mold as casting cores, the mold is filled with molten iron. As the molten iron cools down, it crystallizes and the metal pipes 2 are reliably fixed in the casting due to shrinkage resulting from the crystallization of the molten iron during its cooling. The result is a casting of a bimetallic cover for TUK. Then, the obtained casting of the bimetallic cover for TUK is sent for machining, then to its lower part by means of a mechanical connection, for example, a welded joint, the supporting bottom 4 and the bottom 5 are attached.

Next, a bimetallic cover for TUK is placed inside the container body 9 of the transport and packaging set. A drain hole 8 is made connecting the inner space 6, located between the support bottom 4 and the bottom 5 with the environment. Close the drain hole with plug 8. In the channels formed by metal pipes 2, in a monolithic housing 1, fuel assemblies with spent nuclear fuel are placed. The container body 9 is hermetically closed with two covers 10, 11, the space between which is filled with neutron-protective material 12, and transported to the destination.

Due to the fact that the bimetallic cover for TUKs will have a large mass, which will favorably affect its ability to provide neutron protection, it is advisable to make it non-removable with respect to the container of the transport and packaging set. In order to ensure the possibility of decontamination of the internal space of the bimetallic cover for TUK, it is equipped with a support bottom 4 and a bottom 5, which are mounted in such a way that a free internal space is provided between them 6. When carrying out decontamination operations, decontamination compositions are fed into channels 3, through channels 3, rinsing at the same time, from their inner surface, radioactive contaminants fall through the holes in the support plate 4 into the inner space 6, while accumulating at the bottom 5 and are discharged through the drain hole 8 out.

The proposed design of the bimetallic cover for TUK is distinguished by its low cost and high adaptability, due to the simplicity of the design.

Due to the fact that in the bimetallic case for TUK, metal pipes 2 are poured into the casting of the monolithic body 1, reliable contact is made between them along the entire lateral surface, which ensures good heat removal from the fuel assemblies with spent nuclear fuel located in the channels 3 to the monolithic case 1.

The presence of metal pipes 2 in the design of the bimetallic cover for TUK will make it possible to manufacture case 1 by casting from high-strength cast iron with spherical graphite, a material having good radiation-protective properties and a relatively low cost, and at the same time provide an opportunity for easy cleaning of channels 3 from radiation contamination during decontamination TUK after extraction of fuel assemblies from it. Due to the fact that the connection between the metal pipes 2 and the monolithic body 1 is due to the shrinkage that occurs during the crystallization of the molten iron during the casting of the monolithic body, its high strength and good heat dissipation will be ensured without the use of additional fasteners and operations.

BIBLIOGRAPHY

1. Description of the invention to patent RU 2593388, priority 04/08/2015, published 08/10/2016, bull. Number 22.

2. Description of the invention to patent RU 2463677, priority 04/22/2011, published 10/10/2012, bull. No. 28.

3. Description of the utility model for patent RU 75496, priority February 27, 2008, published August 10, 2008, bull. Number 22.

Claims (1)

A bimetallic cover for TUKs, including a monolithic body with channels for installing fuel assemblies, characterized in that the channels are framed by metal pipes that are fixedly fixed in the monolithic body due to shrinkage occurring during the crystallization of molten iron during the manufacture of casting a monolithic body.

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