RU2781071C1 - Dampering device of the container compartment of the storage pool - Google Patents

Abstract

FIELD: damping devices.

SUBSTANCE: invention relates to a damping device for a spent fuel pool container compartment. The device includes a multi-level damper, composed of two groups of damping elements with the possibility of their installation in one level into each other. The upper damping element in the upper group is made in the form of a base plate with increased rigidity due to its spatial structure, formed by radial elastically deformable elements in the form of T-beams or I-beams, the outer ends of which are fixed on the embedded elements of the walls of the container compartment of the cooling pool by means of fasteners that break under shock loads. The damping elements that make up the underlying multilevel damper are supplemented with plate elements attached to the upper annular plate along the annular rows with a given deflection and with a height decreasing towards the center of the damping element. Thrust rollers are placed on the lower annular plates of the damping elements of the upper and lower groups, and the damping elements of the lower group of the multilevel damper are reinforced by pipe sections installed between the radial ribs and attached to the lower and upper annular plates, the base plate is formed with the possibility of creating a "dry" volume under it.

EFFECT: increasing the reliability of the device operation in normal modes and preventing the possibility of damage to the elements of the spent fuel pool container compartment in emergency situations.

4 cl, 7 dwg

Description

The present invention relates to the field of nuclear energy, in particular to devices installed in the container compartment of a nuclear power plant spent fuel pool, and can be used to prevent possible accidents in the event of a fall of heavy reloaded objects - a container with spent fuel assemblies or a transport cover with fresh fuel assemblies, with a large (about 20 m) height, leading to the destruction of the building structures of the nuclear power plant, as well as to the destruction of fuel elements, leading to a nuclear hazard.

Large modern transport containers with spent fuel assemblies (SFA), weighing about 110 tons, at the moment of falling can create a load of more than 100 times their weight. Accordingly, the impact force in a collision with an oncoming surface can be more than 11,000 tf. Such a large force impact on building structures, namely, on the bottom of the spent fuel pool container compartment, is unacceptable, because the allowable level of specific load on the bottom of the container compartment is about 1000 tf per sq. m, which, with a pool bottom area of 7 m, will be about 7000 tf.

In addition, the design requirements for NPPs limit the local load, which should be no more than 3500 tf at the place where the damping elements are installed. To prevent emergencies leading to accidents and destruction of the building structures of the spent fuel pool and the NPP building in the event of a fall of reloaded objects, damping devices are used,

installed on the bottom of the object to be protected, in particular, on the bottom of the container compartment of the spent fuel pool.

A well-known depreciation system is designed to protect the object from abnormal loads (in space technology, the automotive industry, shipbuilding, mechanical engineering, instrumentation, etc.) and includes a set of shock absorbers forming n≥2 groups, each of which is located along the ring, the plane of which is perpendicular to the longitudinal axis of the object, while at least two groups of shock absorbers are additionally introduced into the system, fixed diametrically opposite to each other on the body of the object (description of the patent for the invention RU No. 2209352, publ. 27.07.2003).

The disadvantage of the system is the impossibility of protection against shock loads of surfaces with which the protected object can contact in one way or another (for example, when falling).

A damping device is known to be installed in the container compartment of the nuclear power plant spent fuel pool, which contains a plate installed by means of a support on the bottom of the container compartment and an energy-absorbing device located under it, installed inside the support on the bottom of the pool. The energy-absorbing device is characterized by the execution as a set of at least two modules installed on top of each other, equipped with horizontal dividing plates, while the modules are made in the form of sectors and shells with the formation between them of a continuous cavity filled with balls and empty cavities, while the thickness of the walls of the shells modules and horizontal plates increases as they approach the bottom of the pool, and the inner surfaces of the shells and lower surfaces

horizontal plates are equipped with weakening risks (Description of the patent for the invention No. 2200989, publ. 03/20/2003).

The disadvantage of the damping device is a reduced level of protection of the structural elements of the bottom of the container compartment due to the impact of the impact load from the support that receives the loads from the plate, which is the first to be affected by the impact load when heavy overloaded objects fall, and which transfers it to the support, which can lead to serious damage to bottom elements before the moment of operation of the energy-absorbing device. Particularly significant can be damage to the structural elements of the bottom of the container compartment during an oblique fall of a CT or a container with GPV (when falling at an angle), when the impact force falls on one side of the slab and support.

The closest technical solution in terms of purpose, essence and achieved result to the claimed shock absorber is a stationary damper installed in the spent assemblies holding pool, which is designed to absorb energy and mitigate shocks when loaded shipping containers fall from a great height (15-20 m) to the bottom of the container compartment of the NPP spent fuel pool.

The damper is a set of metal damping elements installed on top of each other in several rows (up to 10-15 rows) in height. Structurally, each damping element consists of two parallel flat annular plates separated in height by peripheral radial ribs, straight or having a given initial bend. The heights of all damping elements are the same, but the diameters of the rings are different, so that one element within each row can be inserted into others.

(http://www.ckti.ru/aes5.html - Site of NPO CKTI: Products - Development and supply of power equipment - Equipment for nuclear power plants)

A disadvantage of the well-known design of the damping device is the possibility of a sharp operation of all damping elements when a heavy container with OPV falls under conditions of an unevenly distributed load, which can lead to the "collapse" of the damper and the transfer of significant forces to the protected structural elements of the container compartment of the cooling pool, which can lead to damage. the latter, also lead to unacceptable overloads, as a result of which their destruction may occur on the GPV. A particularly high probability of such events occurs with a one-sided impact load on the damper, which is created when the reloaded containers fall in an inclined position, at which there is a sharp one-sided deformation - compression of the dampers with sequential deformation of the damping elements with a "domino" effect, while there is a threat of collapse of the damper with decrease in damping properties and, as a result, damage to fuel assemblies and elements of building structures of the bottom of the container compartment of the spent fuel pool.

The problem solved by the improvement of the damping device claimed as an invention is to increase the reliability of the latter under shock loads caused by the fall of a container with OPV or a container with fresh fuel.

The technical result when using the invention is to increase the damping properties of the device due to the uniform distribution of the shock load on the damping elements, which, sequentially deforming, smoothly dampen the impact energy when falling as a very heavy container with OPV, and more

lung - with fresh fuel, while preventing damage to fuel assemblies and elements of building structures of the bottom of the container compartment of the spent fuel pool.

The problem is solved by the fact that in the damping device of the container compartment of the spent fuel pool, which includes a multi-level damper, composed of damping elements containing annular plates separated by radial ribs fixed between them - straight or with a given bend, and characterized by the possibility of installing damping elements at the same level of each other into another, according to the invention, the upper damping element is made in the form of a base plate with increased rigidity, determined by its spatial structure, which is represented by radial elastically deformable elements located between the upper and lower annular plates in the form of T-beams or I-beams, the outer ends of which are fixed to the embedded elements of the walls container compartment BV by means of fasteners that break under shock loads, and the damping elements that make up the underlying multi-level damper are divided in height into two groups, while the damping elements the upper and lower groups are supplemented with plate elements attached to the upper annular plate along the annular rows with a given bend and with a height decreasing towards the center of the damping element, and on the lower annular plates of the damping elements, indented from the additional plate elements, thrust rollers are placed, and the damping elements of the lower groups of a multilevel damper are reinforced with pipe sections installed between the radial ribs and attached to the lower and upper annular plates, in addition, the spatial structure

the base plate is formed with the possibility of creating a "dry" volume under it in the area of the multilevel damper.

The novelty of the technical solution lies in the implementation of the upper damping element in the form of a base plate with increased rigidity due to its spatial structure, which is represented by radial elastically deformable elements located between the upper and lower annular plates in the form of, for example, T-beams or I-beams, the outer ends of which are fixed on embedded elements of the walls of the container compartment BV by means of fasteners that break under shock loads, as well as in the implementation of the underlying multi-level damper divided in height into two groups, while the damping elements in the upper and lower groups are supplemented by plate elements attached to the upper annular plate along the annular rows with a given bending and with a height decreasing towards the center of the damping element, and on the lower annular plates of the damping elements, indented from the additional plate elements, thrust rollers are placed, and the damping elements of the lower the groups of the multilevel damper are reinforced by pipe sections installed between the radial ribs and attached to the lower and upper annular plates, in addition, the spatial structure of the base plate is formed with the possibility of creating a “dry” volume under it in the zone of the multilevel damper.

The execution of the upper damping element of the multilevel damper in the form of a base plate with increased rigidity due to its spatial structure, for the organization of which elastically deformable radial elements installed between the annular plates in the form of fixed on

the embedded elements of the walls of the container compartment are T-beams or I-beams, which ensures the distribution of the shock load over the entire surface of the damping devices. The radial elastically deformable elements used in the structure of the base plate in the form of T-beams or I-beams operate with minimal deformations during normal handling operations, and under impact load they absorb part of the impact energy due to the calculated elastic deformation. Due to the fastening of the outer ends of the elastically deformable elements of the base plate on the embedded elements of the walls of the container compartment of the BV by means of fasteners that break at design loads, under impact loads, the latter are gradually loaded to the design force of their breakage due to deformation of the base plate. After the breakage of the fasteners, the base plate rests on the underlying multi-level damper, represented by two groups of damping elements separated by height. When the damping elements of the upper group are loaded, which are represented by radial ribs attached to both annular plates and attached only to the upper annular plates by plate elements decreasing towards the center in height with a given bend and thrust rollers placed on the lower annular plates, there is a sequential deformation of the radial ribs and additional plate elements with a given bend, which, with a decrease in the distance between the annular plates, rest against the thrust rollers and, due to the height of the additional plate elements decreasing towards the center of the damping elements, the damping elements “fold”, turning in the radial direction and distributing the impact load on the damping elements bottom group. Then, in the process of damping the shock load, the damping elements of the lower

groups reinforced by pipe sections installed between the radial ribs and attached to the lower and upper annular plates, which are more rigid and provide increased impact resistance, which is necessary to absorb the load from a falling heavier container with OPV.

Even when containers with GPV or transport covers with fresh fuel assemblies fall with an inclination (within the container compartment), the impact load is perceived by the base plate, is partially damped due to the elastic deformation of the beams that form its spatial structure and, with the joint movement of the detached base plate down together with by an object that has fallen on it, is evenly transferred to the underlying damping elements of a multilevel damper, in which a combination of “soft” deformation of the upper group of damping elements and more rigid damping elements of the lower group is realized.

The spatial structure of the base plate also provides for the possibility of creating a “dry” zone under it due to the possibility of using membrane units in it. When the damping device operates in a “dry” zone during the reloading of objects in the normal mode, corrosion processes of the damping elements of the multilevel damper, which are caused by the working medium used in the coolant pool, are excluded, which increases the reliability of the damping device.

The cumulative effect of load balancing on the damping elements of a multilevel damper with a base plate with increased rigidity due to its spatial structure formed by radial elastically deformable elements in the form of T-beams or I-beams, the outer ends of which are fixed on the embedded elements of the walls of the BV container compartment

by means of fasteners breaking off at shock design loads, it allows to more effectively and evenly dampen the impact energy due to the elastic deformation of the base plate elements and ensuring a distributed load on the multilevel damper, the damping elements of which also have increased resistance due to the addition of plate elements mounted on the upper annular plates and installed with different heights along the annular rows, and increased rigidity of the damping elements of the lower group, reinforced with pipe sections installed between the radial ribs. At the same time, ensuring the operation of the damping device in the “dry” zone of the spent fuel pool container compartment eliminates the corrosive effect of the spent fuel pool water solution on the damping device elements, which ensures an increase in the damping device reliability and prevents damage to the spent fuel pool container compartment structural elements during normal operation and in emergency conditions. situations.

An example of the implementation of the damping device of the container compartment of the spent fuel pool is illustrated by sketches.

In FIG. 1 shows the placement of the damping device in the container compartment of the BV.

In FIG. 2 shows a general view of the damping device

In FIG. 3 shows view A in FIG. 2 - base plate, top view.

In FIG. 4 shows a sketch of a multi-level damper with two groups of damping elements.

In FIG. 5 shows the damping element of the upper group of the multilevel damper.

In FIG. 6 shows the damping element of the lower group of the multilevel damper.

In FIG. Figure 7 shows a sketch of the attachment of the base plate to the embedded elements of the walls of the cooling pool (BV) of a nuclear power plant (view B in Fig. 7).

The damping device is installed in the container compartment 1 (Fig. 1) BV. The damping device contains:

- equipped with the elements of the socket of the universal 2 placed on top of the base plate 3, having a spatial structure represented by annular plates 4 (Fig. 2) and radially installed between them T-beams (or I-beams) 5, the outer ends of which are fixed on the embedded element 6 of the wall of the BV container compartment fastener nodes 7, breaking off at shock design loads;

- multi-level damper 8, consisting of two groups of damping elements: the upper group 8a (Fig. 4), which is subjected to plastic deformation under shock loading and the reinforced lower group 86, installed on top of each other in several (about 13-15) levels, including outer 14 and nested internal modules 15 (Fig. 5).

The base plate 3 is the upper damping element (Fig. 1) of the multi-level damper 8 (Fig. 1, Fig. 2 and Fig. 4) and includes a diaphragm 9 (Fig. 3) with a drainage outlet 9a equipped in it to relieve leakage of the working medium from container compartment. The diaphragm 9 with a drainage outlet 9a is attached to the embedded elements 6 (Fig. 2 and Fig. 7) of the wall lining of the BV container compartment (the container compartment in the variant of the project under development has a transverse

section shape of an octagon) and ensures the creation of a "dry" volume in the area of the multilevel damper 8.

Mounting units 7 (Fig. 2, Fig. 3) used for fastening the base plate 3 are designed for the load of the base plate by the reloaded object and are represented by brackets 10 fixed by means of bushings 11 and studs 12 with nuts 13 (Fig. 2, Fig. 7 ) on the surface of the embedded elements 6 (Fig. 1, Fig. 2 and Fig. 7) installed in the walls of the BV compartment. The peculiarity of mounting the base plate 3 to the embedded elements 6 in the walls of the container compartment of the BV is that in all modes of operation it serves as the basis for the universal socket, but in the event of a fall of the container or CT with GPV, it ensures uniform distribution of the shock load over the entire surface of the multilevel damper. To do this, the material and dimensions of the studs are chosen so that when a certain total load is reached (when a container with OPV or CT with fresh fuel falls), which occurs under the action of radial beams 5 elastically deformed under impact load, the studs would break without destroying the support plate and brackets , enabling the base plate with a universal socket and a container with an OPV or a transport cover with fuel assemblies that have fallen on it to fall onto a multi-level damper.

Multi-level damper 8, consisting of several (about 13-15 levels) damping elements stacked on top of each other, is located in the "dry" volume of the container compartment, created by the base plate with the diaphragm 9, introduced into the structure of the base plate 3, and is structurally divided in height into two groups of damping elements (Fig. 4). Each level of the upper and lower groups of damping elements is made up of 14 outer and nested

internal modules 15 (Fig. 4 and Fig. 5). The outer modules 14 of the upper group of damping elements and the inner modules 15 inserted into them are made in the form of two parallel plates: upper 16 and lower 17 (Fig. 5), separated by radial, fixed vertically to both plates, plate ribs 18, formed with a given bend along line parallel to the surface of plates 16 and 17.

To the upper plates 16 in each module 14 and 15, between the radial ribs 18, additional plates 19, 20 and 21 are attached, installed in annular rows (Fig. 5) and differing in height - with a decrease in the height of the plates in the annular rows located closer to the center of the module damping element, and on the lower plates 17 (Fig. 5) of modules 14 and 15, with an indent from the edge of the additional plates 19, 20 and 21, rollers 22 are placed, which act as thrust elements, which are welded to the surface of the plates 17 so that the ends additional plates 19, 20 and 21 did not slip on the surface of the lower plates 17 during compression of the damping modules. Each damping element includes additional plates of several types that differ in height, width and thickness. Plates 19, 20 and 21 are also made with a given deflection along a line parallel to the surface of plates 16 and 17.

In the damping elements 23 of the lower group (in Fig. 6), also composed of outer 24 and inner 25 annular modules, also including the upper 26 and lower annular plates 27, except for the radial ribs 28 attached to both annular plates and the lamellar ribs attached to the upper plates 26 elements 29, 30, and 31, equipped with thrust rollers 32,

located on the lower annular plates 27, between the radial ribs 28, pipe segments 33 are rigidly fixed, the height of which corresponds to the height of the radial ribs 28.

The device works as follows. The spatial structure of the base plate 3 forms a metal structure of increased rigidity, in which the radial elastically deformable beams 5, fixed on the supporting metal structure inside the plate, contain elements of fastening to embedded parts 6 of the walls of the cooling pool in the form of breaking pins 12 (in Fig. 2) at a given force, arising from the deformation of elastically deformable beams under the action of shock loads.

During normal operation of the container compartment of the spent fuel pool, the reloaded object is installed on the plate 3, while the multilevel damper 8 remains unloaded, since the weight of the reloaded object is perceived by the base plate 3 with elastically deformable beams 5, the ends of which are fixed on the embedded elements 6 of the walls of the cooling pool with fasteners, including brackets 10, bushings 11 and studs 12 with nuts 13 (in Fig. 2, Fig. 7), designed for operating loads from the total weight of the base plate and the object being reloaded.

When reloaded objects fall into the container compartment of the BV, the base plate 3, fixed through beams of a given rigidity on the embedded elements 6 of the walls of the BV, with studs 12 used in fastening units that break at the calculated specified load that occurs after the elastic deformation of the beams 5 in

damper 8, which resists sequentially "folding" damping elements of the upper group 8a due to the actuation of radial plate ribs 18 at each level, attached to the annular plates 16 and 17, and additional plates 19, 20 and 21, which, when the distance between the annular plates abut against the rollers 22, creating additional resistance to shock loading. The damping elements of the upper group sequentially “fold”, turning in the radial direction due to the additional plates 19, 20 and 21 decreasing towards the center and distributing the shock load to the damping elements of the lower group. Damping elements of the lower group 86, reinforced installed between the radial ribs 25 and attached to the lower 23 and upper 24 annular plates pipe segments 30, which have greater rigidity, provide increased resistance to shock loading.

As a result, the smooth damping of the impact energy is ensured by the successive “activation” of the base plate 4 during the elastic deformation of the beams 5 and the breakage of the studs 12 in the fastening unit 7, by uniform sequential plastic deformation of the damping elements in the upper group of damping elements 8a of the multilevel damper 8 and by the absorption of residual loads by the reinforced lower group 86 damping elements.

Diaphragm 9, attached to the embedded elements 6 (in Fig. 2) of the cladding of the wall of the container compartment of the spent fuel, is equipped with a drainage outlet 9a to drain the leakage of the working solution from the volume of the container compartment of the coolant, which ensures the creation of a "dry" volume in the area of the multilevel damper 8.

leakage of the working solution from the volume of the container compartment of the BV, which ensures the creation of a "dry" volume in the area of the multilevel damper 8.

The use of the damping device of the proposed design in the container compartments of the BV, due to the formation of a controlled resistance to the shock load due to the sequential "activation" of the base plate during elastic deformation of the elements that determine its spatial structure in the form of T-beams or I-beams, leading to the subsequent breakage of the fastening units, transfer of a uniform load to the surface of the damping elements, and due to the alignment of the direction of impact and the uniform transfer of the shock load through the base plate to the surface of a multi-level damper, which provides consistent smooth resistance to plastically deformable damping elements of the upper group and rigid radial resistance to damping elements of the lower group, causes a smooth damping of the impact energy and protects the contents container with GPV or a transport cover with fuel assemblies and structural elements of the container compartment and spent fuel from damage.

Claims (4)

1. The damping device of the container compartment of the spent fuel pool, including a multi-level damper, composed of damping elements containing annular plates, separated by peripheral radial ribs fixed between them - straight or with a given camber, and characterized by the possibility of installing damping elements at the same level into each other, different the fact that the upper damping element is made in the form of a base plate with increased rigidity, determined by its spatial structure, which is represented by radial elastically deformable elements located between the upper and lower annular plates, the outer ends of which are fixed on the embedded elements of the walls of the container compartment of the BV by means of breaking under shock loads fasteners, and the damping elements that make up the underlying multi-level damper are divided in height into two groups, while the damping elements in the upper and lower groups are supplemented by those attached to the top on the lower annular plate along the annular rows by plate elements with a given bend and with a height decreasing towards the center of the damping element, while on the lower annular plates of the damping elements of the upper and lower groups, thrust rollers are placed indented from the additional plate elements, and the damping elements of the lower group of the multilevel damper are reinforced installed between the radial ribs and attached to the lower and upper annular plates, pipe sections, in addition, the spatial structure of the base plate is formed with the possibility of creating a "dry" volume under it in the area of the multilevel damper. 2. The damping device of the spent fuel pool container compartment according to claim 1, characterized in that the radial elastically deformable elements in the base plate are in the form of a T-beam or an I-beam. 3. The damping device of the spent fuel pool container compartment according to claim 1, characterized in that the additional plate elements attached to the upper annular plate along the annular rows are made with a height decreasing towards the center of the damping element. 4. The damping device of the spent fuel pool container compartment according to claim 1, characterized in that a membrane unit with a diaphragm and a drainage outlet is formed in the spatial structure of the base plate to create a “dry” volume in the area of the damper.

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