RU56704U1 - TRANSPORT PACKAGING KIT FOR TRANSPORTATION AND STORAGE OF WASTE HEATED FUEL ASSEMBLIES - Google Patents

Abstract

The utility model relates to devices for transporting and storing spent fuel assemblies (SFA), provides a reduction in shock loads on SFA. The transport packaging set contains a container body, an inner and an outer lid, a cover for installing a SFA, and dampers. The container body is made of high-strength cast iron with spherical graphite, lifting trunnions are installed on its side surface. The cover is made in the form of stainless steel channels forming a block, each of which is a square tube. Outside, the cover is equipped with at least three stiffeners, at least four lower posts are installed in its lower part, and the central rack with a grip device in its upper part passes through the center, in addition, the cover is equipped with support for SFAs, and the central and lower racks pass through the support and are attached to it. The cover is fixed in an airtight cup installed with an interference fit in the container body. A sealed glass is formed by stainless steel lining of the inner surface of the housing, the surface of the housing for the installation of covers and part of the outer surface of the housing at the installation sites of dampers. Wooden dampers, made of elements arranged in layers with alternating longitudinal and transverse positions of the layers, are enclosed in a stainless steel sheath, mounted on the ends of the container, the lower and upper dampers being pulled together by pins. 1 n.p. f-ly, 1 Fig.

Description

The utility model relates to nuclear energy, to devices for transporting and storing spent nuclear fuel (SNF) of nuclear power plants (NPPs), research reactors (IR) and ship installations in the form of spent fuel assemblies (SFA) and can be used for transportation of SFAs for transportation taking into account the possibility of emergency situations.

For transportation and storage of spent fuel assemblies, transport packaging kits (TUKs) are used, which, due to the lack or lack of SNF processing facilities, are also used for intermediate and sometimes long-term storage of spent fuel assemblies.

The main danger in the transportation of SFAs is the possibility of an uncontrolled spontaneous chain reaction of fission of nuclei, which is accompanied by the release of significant energy up to the occurrence of a thermal explosion. In addition, SFAs are sources of powerful ionizing radiation, and safety is required, in particular, for maintenance personnel involved in loading and unloading SFAs.

In accordance with the standards of nuclear and radiation safety and IAEA recommendations, packaging sets must provide high radiation-protective and strength properties, including in emergency situations, possible during the transportation and storage of SFAs.

Along with this, packaging kits created for the transportation and storage of highly active SNF should provide the ability to use existing infrastructure (for example, lifting and transport vehicles) designed for SNF management.

For devices designed for transportation and storage of spent nuclear fuel, the most dangerous are the dynamic loads that occur during emergency situations. Such situations are collisions of vehicles carrying containers (railway accident), as well as a blow to the container of heavy aircraft parts.

The requirements for such devices determined the composition of the main elements included in the transport packaging, namely: the container body with a cavity, one or more covers with locking elements, a cover for the SFA, and shock absorbers (dampers).

A known container for transportation and long-term storage of spent fuel assemblies of nuclear power plants according to patent RU 2148864, G 21 F 5/008, publ. 2000.05.10, comprising an outer casing with a cover, shock absorbers, an inner casing with a cover and with means for fastening with an outer casing, supported by shock absorbers rigidly fixed at the bottom of a horizontally located outer casing, provided with a cover with SFA sockets installed in the inner casing, the cover of the outer casing is located at its end, and its inner surface is equipped with rigidly fixed and evenly spaced shock absorbers, while at the bottom of the outer casing the shock absorbers are equally It’s different, and each shock absorber is made up of glasses made in the form of hollow metal cylinders of different

diameter installed in each other with gaps in the direction of application of the load and rigidly interconnected at the interface.

The known container is made forged all-metal, which implies the high complexity of manufacturing and, consequently, high cost.

A device for transporting and (or) storing cargo according to the patent RU 2133061, G 21 F 5/00, publ. 1999.07.10 containing container and shock absorbers. A protective shell is introduced into the container, connected to it by an adapter that ensures the safety of the load under normal operating conditions and deforms or collapses in emergency situations, the protective shell being made either in the form of a segment, and shock absorbers are located on one side between the container and the segment, and on the opposite side between the container and the cargo, or in the form of a capsule, and shock absorbers are located between the container and the capsule.

When using this device in emergency situations, overloading on the load is reduced by compressing the shock absorbers, and for this the geometrical parameters, stiffness and strength properties of the adapter are deformed or destroyed, allowing the cargo with a segment or capsule to move and compress the shock absorbers.

A common disadvantage of the two devices mentioned in patents RU 2148864 and RU 2133061 is that the case is not protected when dropped under loading conditions for subsequent transportation and possible drops during transportation, since the damping structural elements are installed inside the container body.

Known transport and packaging for transportation and storage of spent nuclear fuel according to patent RU 2127919, G 21 F 5/008, publ. 1999.03.20, comprising a cover, a housing with a cavity, a cover, fixing elements mounted on the inner surface of the housing, characterized in that on the cover made with a removable cover and provided with retractable stops, a protective shell with a diameter larger than the diameter of the cover included in the bore is installed on the inner surface of the housing, while dowels are installed on the housing bore.

The disadvantage of this transport and packaging kit is that its use allows to increase the nuclear safety of transport and handling operations, but does not provide radiation safety in cases of emergency destruction of the container body.

A known container for transporting and storing spent nuclear fuel according to the copyright certificate SU 1630558, G 21 F 5/00, publ. 04/04/15/15, containing a vertically mounted metal housing having the shape of a cylinder, damping ribs mounted on the housing, having the shape of flat horizontal rings, with protrusions, radiation protection, consisting of hollow cylinders located between the damping ribs, and containing neutron-shielding material, the hollow cylinders radiation protection made of metal with a coefficient of thermal expansion greater than the coefficient of thermal expansion of the material of the case, and have vertical through holes, filled nye neytronozaschitnym pictures, and the projections have the form of rings and ribs form with the damper T-shaped profile, the hollow cylinders are mounted on the radiation protection casing with an interference fit, and between the protrusions and the hollow cylinders are made ignition gaps.

In such a container, the damping ribs create a sufficiently high impact resistance in emergency situations. However, the drawback of the container is that the set of elements providing shock damping in the container is operable in a relatively narrow range of loads - from the load that causes the onset of elastic deformation of the elements to the load, with increasing which elements collapse and stop damping.

The closest in combination of features is a container for transporting radioactive material of fuel according to patent RU 1144632, G 21 F 5/00, publ. 1985.03.07, which is a cylindrical container with two lids with a carbon steel casing, a stainless steel cover is inserted into the cavity for installing spent fuel assemblies. On the outer cover and under the bottom of the housing, dampers are installed, consisting of two stainless steel walls. Six lifting pins are installed on the container. The inner closure cover is made of carbon steel, the outer cover is made of stainless steel. The means for attaching the covers to the housing provide sealing of the housing cavity. The container cavity and the outer parts are covered with stainless steel sheet and form a sealed glass. In addition, the cylindrical part of the housing is surrounded by an outer casing of the water shell provided with annular steel cooling fins. Thick-walled pipes are installed in the damper cavity and balsa wood is placed as the energy-absorbing material, and the side surface of the damper has a toroidal shape.

If the container falls in the axial direction, kinetic energy at the moment of impact is absorbed by the outer damper cup, the pipes installed in it, and the balsa wood packing. In case of impact of the side wall of the container, the kinetic energy is absorbed by the side surface of the outer damper cup made in the form of a torus and massive annular ribs. Absorption of kinetic energy of impact by balsa wood in this case is absent.

The disadvantage of the prototype is the low security of its side surface from shock loads when dropped, especially when dropped on a pin (emergency situation provided for by the IAEA regulatory documents).

The proposed utility model is aimed at solving the problem of increasing the nuclear and radiation safety of the transportation and storage of SFAs by increasing the protection of SFAs from damage and destruction both in normal use (storage and transportation by all modes of transport) and in emergency situations, for example, when transport packaging sets fall with SFA or when vehicles collide with each other or with an obstruction.

When solving this problem, the utility model provides a technical result, which consists in reducing the shock loads on the SFA, regardless of the direction of impact in emergency situations.

The specified technical result is achieved by the fact that in the transport packaging for transportation and storage of spent fuel assemblies, comprising a container body with lifting pins mounted on its side surface, an inner lid and an outer lid made of stainless steel, mounted on the housing with fastening and sealing means, and forming two airtightness barriers with a body, a cover with stainless steel channels for installing spent fuel assemblies, inserted placed in a sealed glass installed in the body cavity and formed by stainless steel lining of the internal surface of the body, the surface of the body for installing covers and parts of the external surface of the body at the installation sites of dampers, and wooden dampers enclosed in a stainless steel shell and mounted on the ends of the container , the container body is made of high-strength cast iron with spherical graphite, the inner lid is made of stainless steel, the cover is fixed in a sealed glass installed with an interference fit the container body, and is made in the form of channels forming a block, each of which is a square tube, the outside of the case is equipped with at least three stiffeners, at least four lower posts are installed in its lower part, and passes through the center a central rack with a device for capturing in its upper part, while the cover is equipped with a support for spent fuel

assemblies, and the central and lower racks pass through the support and are attached to it, in addition, the lower and upper wooden dampers are pulled together and made of elements located in layers with alternating longitudinal and transverse positions of the layers.

In the event of an accidental drop in the TUK, the forces acting on the SFA upon impact depend on the deformability of the TUK elements that perceive dynamic loads directly (container body and dampers) or indirectly (external and internal covers and covers). In the proposed utility model, the casing is made of high-strength cast iron with spherical graphite, which has high deformation ability (ductility) and high resistance to brittle fracture, both at normal and negative temperatures up to minus 40 ° С. The cover, which is a rigid welded construction, ensures the preservation of the ordered arrangement of the SFA and prevents damage and destruction of the SFA. Rigidity ribs welded on the outside of the cover ensure fixation in the radial direction and exclude deformation of the cover channels when the container falls in a horizontal position. Wooden dampers are made of elements in the form of boards or bars made of spruce and arranged in layers with alternating longitudinal and transverse positions of the layers. For use as a damping material, spruce has a number of properties: high deformation ability (up to 50% -60%) with a weak dependence of resistance on the degree of deformation, high energy absorption and anisotropy of mechanical properties in the longitudinal and transverse position of the fibers, which allows to obtain the necessary mechanical characteristics of the damper to reduce shock loads on the TUK elements when it falls in any position on a rigid base.

The essence of the utility model is illustrated in the drawing. The figure shows a transport packaging set. The TUK contains a container body 1, an inner lid 2 and an outer lid 3, fasteners 4 and seals 5 of the lids 2 and 3, a cover 6 with channels 7 for installing a SFA, an airtight cup 8, three stiffeners 9, four lower racks 10, a central rack 11, support 12 for spent fuel assemblies, dampers 13, lifting trunnions 14.

The container body 1 is molded together with the bottom from ductile iron with spherical graphite. A stepped bore is made in the upper part of the housing 1, in which an inner cover 2 and an outer cover 3 are installed with fastening means 4 in the form of studs and a seal 5 in the form of rubber o-rings, and creating two airtightness barriers with the container body 1. Inner cover 2 and outer cover 3 are made of stainless steel. The internal cavity of the container body 1, the surface for the installation of the inner cover 2 and the outer cover 3 and part of the outer surface of the container body 1 have a composite weldable stainless steel lining, forming a sealed glass 8.

On the side surface of the housing 1 mounted and reinforced lifting trunnions 14 made of stainless steel.

Inside the case 1 of the container is inserted a cover 6, designed for the orderly placement of SFA. Cover 6 with channels 7 is a welded structure of square tubes made of stainless steel. The pipes are welded together and form a block, for example, of twenty or forty-eight channels 7 for placement of SFAs in them. Three stiffening ribs 9 are welded to the blocks formed from channels 7 from the outside, and four lower posts are welded to the lower part 10. A central square-shaped post 11 with a grip device in the upper part passes through the center of the block. The lower struts 10 and the central strut 11 pass through the support for the SFA in the form of a ring, made in the form of a ring, and are rigidly attached to it.

At the ends of the container body 1, wooden dampers 13, lined with stainless steel, are installed and pulled together by four studs. Dampers 13

made of wooden elements (boards, bars) located in layers with alternating longitudinal and transverse position of the layers. In the upright position, the lower damper mounted on the bottom of the housing 1 serves as the basis for the TUK.

A utility model can be implemented as follows:

The completed TUK enters the premises for loading. Before loading the SFA into the transport packaging set, the dampers 13 are removed and the outer cover 3 and the inner cover 2 are sequentially unfastened and removed to the storage position. The container body 1 with the cover 6 is installed in the loading pool, the pool is filled with water and sealed spent fuel assemblies are loaded under water. After loading, the sealing means 5 in the form of rubber rings are installed on the container body 1 and, using the fastening means 4 in the form of pins, the inner cover 2 is attracted to the body 1. After controlling the sealing means 5, the outer cover 3 is installed in the form of rubber sealing rings. Next, the container body 1 with the inner 2 and outer covers installed on it, they are removed from the pool, then dampers are installed and TUK is transported to the temporary storage site. The fat is transported and serviced upright.

Tests of the full-size TUK model when dropped from nine meters confirmed that the claimed utility model ensures the integrity of the hull, prevents the caps from being sealed, prevents deformation and damage to the SFA, and, ultimately, increases the nuclear and radiation safety of the transportation and storage of the SFA and reduces impact loads transported SFA.

Claims (1)

A transport packaging set for transporting and storing spent fuel assemblies, comprising a container body with lifting trunnions mounted on its side surface, an inner lid and a stainless steel outer lid mounted on the housing with fastening and sealing means, and forming two tightness barriers with the housing, case with stainless steel channels for installing spent fuel assemblies inserted into a sealed cup mounted in the body cavity and formed by stainless steel cladding of the inner surface of the housing, the surface of the housing for installing covers and parts of the outer surface of the housing at the installation sites of the dampers, and wooden dampers enclosed in a stainless steel shell and mounted on the ends of the container, characterized in that the container body is made of ductile iron with spherical graphite, the inner cover is made of stainless steel, the cover is fixed in an airtight cup installed with an interference fit in the container body, and is made in de forming a block of channels, each of which is a square tube, the outside of the case is equipped with at least three stiffeners, at least four lower posts are installed in its lower part, and a central rack with a grip device passes through the center in its upper part, while the cover is equipped with a support for spent fuel assemblies, and the central and lower racks pass through the support and are attached to it, in addition, the lower and upper wooden dampers are pulled together and made of ele ENTOV disposed in layers alternating with longitudinal and lateral position of the layers.