RU180654U1 - SEALED AMPOULE FOR THE WASTE HEATED ASSEMBLY - Google Patents

Abstract

The utility model relates to nuclear energy, in particular, to spent nuclear fuel management, and more particularly, to an ampoule that houses a bundle of fuel elements (fuel elements) of an spent fuel assembly (SFA) of an RBMK-1000 reactor with leaky fuel elements. The proposed ampoule contains a cylindrical body with a bottom and a lid containing an inner bore with an annular protrusion, a bottom in the upper part provided with a conical protrusion, and a valve for filling the ampoule with storage medium. The cover is connected to the housing by a hermetic weld after loading the fuel rod bundle into the housing. Above the conical protrusion, a step protrusion is made at the same time, not protruding beyond the generatrix of the conical protrusion. A cylindrical hole is made in the stepped protrusion with the formation of a saddle in the form of an annular protrusion, and a cylindrical and threaded hole is made in the conical protrusion, in which a valve is placed to fill the ampoule with the storage medium. Centering bores with grooved edges for welding. The technical result that can be obtained by implementing the utility model is to create an ampoule with a sealing barrier for aerosol and gas environments and the fact of filling it with the storage medium.

Description

The utility model relates to nuclear energy, in particular to the management of spent nuclear fuel, and more specifically to an ampoule that houses a bundle of fuel elements (fuel elements) of the spent fuel assembly (SFA) of the RBMK-1000 reactor with leaking fuel rods.

At present, bundles of fuel rods (PT) of conditioned SFAs with sealed fuel rods loaded into ampoules are being transported to a dry storage facility for spent nuclear fuel.

In a dry storage, ampoules are reloaded into storage cases. Known sealed storage case for spent nuclear fuel (RF patent No. 2372678, CL. G21F 5/008, 2008), consisting of a housing, grille and cover. The cover is a disk, in the fungus of which a through step hole is made, in which there is a valve for pumping and filling the canister with storage medium. At the end of the fungus, an edge is made for welding the valve. The valve includes a ball in the centering support, a control rod-plug and two springs. An edge is made at the upper end of the control rod-plug for welding with the end of the fungus and sealing the valve.

The valve is opened by an external pusher, which, overcoming the resistance of the springs, moves the dummy rod, the ball, the centering support, compressing the spring. After removing the force from the side of the external pusher, the spring raises the centering support with the ball, and the valve closes. After loading the case of the canister with ampoules with PT, the lid is welded to the case of the canister, and through the valve in the lid, the canister and the ampoules placed in it are evacuated and filled with nitrogen-helium mixture with excess pressure, after which the valve closes. After checking the tightness of the weld seam of the lid with the body, the edges of the plug stem and the end of the fungus are welded, and the pencil case is installed in the storage slot of the dry storage, which is also sealed by welding. “Safety rules for the storage and transportation of nuclear fuel at nuclear facilities” NP-061-05 clause 4.4.2.3. provide that any detachable connection must have at least two sealing barriers, and each barrier should provide design sealing parameters.

Given the long-term storage of spent nuclear fuel, the dry storage project provides for three sealing barriers during storage of spent nuclear fuel, which are sealed welded joints. Based on this, at present, only air-conditioned fuel transfer units are accepted in the dry storage, in which the fuel cladding is the first sealing barrier, the sealed canister is the second, and the storage slot is the third.

Known pencil case for storage of spent fuel assemblies (RF patent No. 2620132, CL. G21F 5/008, 2016), designed to accommodate defective spent fuel assemblies in it. A well-known pencil case contains a housing, a bottom and a lid equipped with two locks installed in the groove of the lid and interacting with the groove in the housing. Locks are pressed by compression springs. Sealing gaskets are installed between the cover and the housing. Slots are made in the locks through which the restrictive screws installed in the cover are passed, and plugs are sealed in front of the screws in the cover. The tightness of the case is ensured by rubber gaskets and is checked at the manufacturing stage by supplying compressed air to the case and immersing it in a container of water.

Work with a known pencil case is as follows.

A case without a cover is installed in the SFA loading post. Defective SFAs, or spills of elements of the active part of the destroyed SFAs, are loaded into the pencil case. Next, the lid is locked and the canister is transported similarly to the transportation of intact SFAs.

The disadvantages of the known pencil case include the fact that after loading a defective SFA into it and installing a cover, it is impossible to check its tightness. The rubber gaskets, based on the drawing, are radial and do not guarantee the leakproofness of a known pencil case after reinstalling the cover. In addition, the use of rubber seals due to the destruction of rubber under the influence of radiation from the SFA and the loss of its elasticity limits their service life and makes it impossible to use the well-known case during long-term storage of defective SFA. Based on this, the known case is a sealed barrier to fuel particles, but is not a barrier to aerosol and gaseous media in the case.

Known ampoule, made in accordance with patent No. 2353010, G21F 5/008 according to the project 1621-28-0007-01 of OJSC Central Design Bureau of Mechanical Engineering (OJSC Central Design Bureau). The ampoule contains a cylindrical body with a bottom, a cover fixed in the upper part of the body with a locking device, installed in the body with a gap in the form of a labyrinth seal, preventing the particles of fuel from spilling out of the ampoule. The labyrinth seal is made on the cover in the form of annular grooves. The lid is fixed by a locking device made in the form of a spring split ring installed in the annular groove of the lid. The lid contains an inner bore with an annular protrusion and a bottom. The bottom in the upper part is equipped with a conical protrusion, and in the lower part is a thin-walled sample, flared to secure the sprocket, which serves to install the spring. The inner bore and the annular protrusion serve to introduce under the annular protrusion of the legs of the capture of the electromechanical non-copying bridge manipulator and subsequent overloading of the ampoules

Known leaky ampoule is a barrier to sealing fuel particles, but is not a barrier to aerosol and gas environments and is therefore intended to transport and store in it only conditioned bundles of fuel rods with sealed fuel rods, the shell of which is the first barrier to sealing.

At the same time, after long-term storage in the on-site storage facilities, part of the fuel rod bundles is substandard with leaky fuel rods, the storage of which in a known ampoule reduces the number of sealing barriers from three to two.

A well-known ampoule is selected by the applicant as a prototype, as the closest device of the same purpose to the claimed utility model.

The task to which the proposed utility model is directed is to create the possibility of transporting and storing in the proposed ampoule of substandard bundles of fuel rods with non-tight fuel rods.

The technical result that can be obtained by implementing the utility model is to create an ampoule with a sealing barrier for aerosol and gas media and the possibility of filling it with a storage medium.

To achieve the named technical result in the proposed ampoule for the spent fuel assembly, including a cylindrical body with a bottom and a lid containing an inner bore with an annular protrusion and a bottom, equipped with a conical protrusion in the upper part, the lid is connected to the housing by a hermetic weld after loading the fuel rod bundle into the housing , over the conical protrusion at the same time a step protrusion is made with it, not extending beyond the generatrix of the conical protrusion, a cylindrical hole with about mation of the saddle in the form of an annular protrusion, and the protrusion formed in the conical and cylindrical threaded hole in which is placed a valve for filling ampoules storage medium.

In the particular case of execution, centering bores are made on the upper end of the housing and on the lower end of the lid.

In another particular embodiment, the valve for filling the ampoule with the storage medium comprises a threaded sleeve with grooves at its end, a spring installed in the sleeve, a plate interacting with the seat through an elastic sealing element, and a plug-rod installed in the hole of the stepped rod.

The connection of the cover to the housing with a hermetic weld after loading the fuel rod bundle into the housing allows to obtain a sealing barrier for aerosol and gaseous media instead of an unpressurized fuel cladding.

The execution of a stepped protrusion on top of the conical protrusion and the execution of a cylindrical hole in the stepped protrusion with the formation of a saddle in the form of an annular protrusion, the execution of a cylindrical and threaded holes in the conical protrusion made it possible to place a valve in them to fill the ampoule with a storage medium, in particular, a nitrogen-helium mixture. This, in turn, allows for quality control of the weld seam of the lid with the body of the pencil case using the "helium probe" method. Performing on a conical protrusion at the same time as a stepped protrusion, not protruding beyond the generatrix of the conical protrusion, allows you to use existing technology and equipment for transport and technological operations with the proposed ampoules in a dry storage.

Performing at the upper end of the body and at the lower end of the cover centering bores allows you to remotely center the cover relative to the body before welding.

The content in the valve of the threaded sleeve with grooves on its end, installed in the spring sleeve and the plate interacting with the seat through an elastic sealing element, made it possible to ensure valve tightness to preserve excess pressure in the valve until the quality control of the weld seam of the ampoule body with its cover and subsequent sealing of the valve by welding and checking the quality of valve welding. At the same time, the force of the pressed plate to the seat is regulated by the position of the threaded sleeve. Installing the plug-plug in the hole of the stepped rod allows you to open the valve by the force of an external pusher and close the valve when removing this force using the spring installed in the sleeve.

The proposed utility model is illustrated by drawings, which depict:

in FIG. 1 - ampoule;

in FIG. 2 - ampoule loaded with a bunch of fuel rods;

in FIG. 3- the upper part of the ampoule after loading the bundle of fuel rods.

The proposed ampoule (see Fig. 1) contains a housing 1 with a bottom 2 and a neck 3 and a lid 4 mounted in the neck 3.

The lid 4 (see Fig. 3) contains an inner bore 5 with an annular protrusion 6 and a bottom 7. The bottom 7 is provided with a conical protrusion 8 in the upper part and a thin-walled selection 9 in the lower part, which is flared to secure the sprocket 10, which serves to install the spring 11. The inner bore 5 and the annular protrusion 6 are used to introduce under the annular protrusion 6 of the gripping legs of the electromechanical non-copying bridge manipulator (not shown in the drawings) when overloading the proposed ampoules.

Above the conical protrusion 8, a stepped protrusion 12 is made at the same time, not protruding beyond the generatrix of the conical protrusion 8. In the stepped protrusion 12, a cylindrical hole 13 is formed to form a saddle 14 in the form of an annular protrusion, and a cylindrical 15 and a threaded 16 hole are made in the conical protrusion 8, in which the valve 17 is placed to fill the ampoule with a storage medium.

The valve 17 contains a threaded sleeve 18 with grooves 19 at its end, a spring 20 installed therein, a plate 21 interacting with the seat 14 through an elastic sealing element 22, and a plug stem 23 with a spring 24 installed in the hole 13 of the stepped protrusion 12. On the upper end of the housing 1 and the lower end of the cover 4 made centering bores 25 and 26

In the neck 3, an inner bore 27 is made, which serves to engage the housing 1 with a gripper (not shown in the drawings).

In the proposed ampoule, a fuel rod bundle 28 is installed (see Fig. 2), after which a weld 29 is applied between the centering bores 25 and 26, and a weld 30 is placed on the ends of the stepped protrusion 12 and the rod end caps 23.

Work with the proposed ampoule is as follows.

At the nuclear power plant, the ampoules enter the cutting chamber located in the cells of the transport cover (not shown in the drawings), from which the ampoules are removed one by one and installed into the shaft, first the cover 4, hooked to the annular protrusion 6, and then the housing 1, hooked to the inner a bore 27 in the neck 3. A bundle of fuel rods 28 is installed in the housing 1, and then a cover 4 is inserted into the centering bore 25 of the housing 1 with its bore 26, which are connected by a weld seam 29 using a welding unit (not shown in the drawings).

Next, using the installation of evacuation and filling with a nitrogen-helium mixture (not shown in the drawings), an external pusher acts on the dummy rod 23, by which it drops down, compressing the springs 24 and 26 and moving the plate 21 from the seat 14, and As a result, valve 17 opens. The internal cavity of the ampoule through the grooves 19 in the threaded sleeve 18 is evacuated, and then filled with a nitrogen-helium mixture, after which the plug-rod 23 is freed from the action of the external pusher, and the valve 17 is closed by the action of the spring 20. Using a helium probe, the tightness of the weld 29 is monitored, and with a positive test result, a weld 30 is superimposed on the ends of the stepped protrusion 12 and the stem plug 23, the quality control of which is carried out in a similar way. Sealed ampoules loaded with bundles of fuel rods are installed in a transport case and transported in a transport packaging set by rail to a dry storage, where they are loaded into canisters for their long-term storage.

Claims (3)

1. An ampoule for a spent fuel assembly including a cylindrical body with a bottom and a cover containing an internal bore with an annular protrusion, a bottom provided with a conical protrusion in the upper part, characterized in that the cover is connected to the housing by a hermetic weld after loading the fuel rod bundle into the housing, over the conical protrusion, a step protrusion is made at the same time, not protruding beyond the generatrix of the conical protrusion, a cylindrical hole is made in the step protrusion with the formation of a saddle in the form of an annular protrusion a, and in the conical protrusion, cylindrical and threaded holes are made in which a valve is placed to fill the ampoule with the storage medium. 2. The ampoule according to claim 1, characterized in that at the upper end of the housing and at the lower end of the lid, centering bores are made with cutting the edges of the lid for welding. 3. The ampoule according to claim 1, characterized in that the valve for filling the ampoule with the storage medium comprises a threaded sleeve with grooves at its end, a spring installed in the sleeve, a plate interacting with the saddle through an elastic sealing element, and a plug stem installed in the hole stepped protrusion.

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