RU2474892C1 - Device for lifting and transfer of used fuel rod arrays - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to safety measures in transfer of used fuel rod arrays from transport shells into those of storage and may be used in water-filled used nuclear fuel storages at nuclear fuel recovery plants, or at nuclear power stations as emergency tools. Proposed device comprises receiving pool, moving platform with running arranged thereunder, lifting device, protective barrel with chamber open on pool side, grip arranged inside said barrel and jointed to bar lower part, bar being mounted on lifting devices, and rod reciprocation drive arranged inside said barrel. Said grip is furnished with fixed and moving jaws, fixed jaws are secured to protective barrel while moving jaws are articulated with cross-arm and fitted in inclined grooves of guide ribs connected to aforesaid barrel. Mating bearing surfaces of jaws are composed of corrugated inclined surfaces with equal angle of inclination.

EFFECT: higher reliability and safety.

3 cl, 3 dwg

Description

The invention relates to nuclear technology, in particular to means for ensuring safety when reloading spent fuel assemblies of the VVER 1000 reactor from transport covers to storage covers, and is intended for use in water-filled spent nuclear fuel storage facilities at such fuel recovery plants or at nuclear power plants as emergency tool.

The core of Russia's nuclear power park is the VVER-1000 and RBMK reactors. For VVER-type reactors, the concept of a closed nuclear fuel cycle has been adopted. Spent nuclear fuel (SNF) of the VVER-1000 reactors will be reprocessed at the RT-2 plant after its commissioning. According to the “Strategy for the Development of Nuclear Energy in the First Half of the 21st Century," the creation of the RT-2 plant is planned for 2020-2025. There is a storage facility for this fuel at the RT-2 site, where the spent fuel of the VVER 1000 reactors is stored in a water-filled pool, the so-called wet storage facility. Spent nuclear fuel enters the pool in a transport case loaded into a protective container. From the transport cover in the overload compartment of the water-filled pool, the spent fuel assemblies (SFAs) are reloaded into storage covers, which are stored in the SFA storage pool from the overload compartment.

Based on the operating experience, a small part of the SFA can come in a transport case with curved heads due to the bending of the guide channels connecting the head of the SFA with the fuel part. Thin-walled guide channels have a diameter of 12 mm and a wall thickness of 0.8 mm; therefore, there is a possibility of tearing off the curved head along the cross-section of these guide channels when removing the SFA from the transport case.

A device is known for lifting and moving spent fuel assemblies overloading spent fuel assemblies, comprising a receiving basin, a movable platform with a running gear mounted above the receiving basin, a lifting device located on the moving platform, a gripper for the spent fuel assembly mounted on the lifting device, a protective cup, fixed on a movable platform having a cavity open from the side of the pool to accommodate part of the spent fuel conductive assembly, the lower edge of the protective glass located below the water receiving basin and grip mounted in the cavity of the protective glass with the possibility of vertical movement (see. USSR Inventor's Certificate №1572304, G21S 19/10).

The disadvantage of this known device is that it is not possible to overload SFAs with curved heads by a known device.

In addition, the water level in the existing receiving pool (storage overload compartment) allows the SFA to be reloaded from the transport cover to the storage cover without the presence of biological protection on the protective glass.

The closest device to the claimed device for a combination of features is a device for lifting and moving spent fuel assemblies, including a protective cup with a grip installed in its cavity, attached to the lower part of the rod mounted on a lifting device, a grip equipped with a reciprocating rod drive located in the cavity of the protective glass, the grip tabs mounted on the spring-loaded rotary axes and when the actuator rod is retracted form a cross section along the inner diameter equal to that of the head of the spent fuel assembly.

The protective cup is made in the form of two flat parallel plates connected by jumpers. The gripper contains two horizontal and two vertical links articulated to each other, and the horizontal links are mounted on a movable axis located in the grooves on the plates of the protective glass, the vertical links are installed in the cavity of the protective glass on the fixed axis, and the gripping tabs are installed in the vertical links on axes fixed in vertical links with nuts.

Belt springs are installed between the nuts and the vertical links. As a capture drive, a pneumatic cylinder is used, connected by tubes to a manual pneumatic distributor installed on the upper end of the rod.

The known device allows you to remove from the transport cover SFA with curved heads, as well as to lift from the bottom of the pool fallen SFA.

At the same time, a safety analysis showed that there is a possibility of a torn head tearing off when a SFA is removed from a transport case by a known device due to a break in the guide channels at the bend. Removing from a transport case SFA without a head, for which the grips of known devices are engaged, is impossible.

The technical result that can be obtained by carrying out the invention consists in the possibility of removing the SFA from the transport covers when its head is torn off by engagement with its guide channels and subsequent installation in a storage case intended for storing defective SFAs.

To achieve the specified technical result in a device for lifting and moving spent fuel assemblies containing a receiving basin, a movable platform with a running gear installed above the receiving basin, a lifting device, a protective cup having a cavity open from the side of the pool, a gripper installed in the cavity of the protective cup and attached to the lower part of the rod mounted on the lifting device, the actuator with reciprocating movement of the rod, placed in the cavity of the protective cups, a feature is that the grip is equipped with fixed and movable legs, the fixed legs are attached to the protective cup, the movable legs are connected by articulated rods mounted on the actuator stem and installed in the inclined grooves of the guide ribs attached to the protective cup and directed normal to motionless paws.

In addition, the mating bearing surfaces of the movable and fixed legs are made in the form of inclined planes with the same angle of inclination, on which the corrugation is applied. A pneumatic cylinder is used as a reciprocating rod actuator, pneumatic throttles with non-return valves are installed in its connecting ports.

Providing the gripper with fixed and movable legs and attaching the fixed legs to the protective cup, when installing the gripper on the SFA without a head, it was possible to place the fixed legs and in the upper position the movable legs on opposite sides of the extreme rows of the SFA guide channels.

The connection of the movable legs with articulated rods with a traverse connected to the actuator stem, the installation of the movable legs in the inclined grooves of the guide ribs attached to the protective cup, and directed along the normal to the stationary legs, allowed the movable legs to move the movable legs along the inclined grooves when extending the actuator stem, bringing them closer along normal to motionless paws. When moving, the movable paws first bend the SFA guide channels located between the movable and fixed paws, and then, flattening them, squeeze between the fixed and movable paws, thereby ensuring that the SFA is engaged in the guide channels.

The implementation of the mating supporting surfaces of the movable and fixed legs in the form of inclined planes with the same angle of inclination makes it possible to obtain, after flattening the guide channels, an area-wide contact between the movable and fixed legs and the tapered guide channels clamped between them, ensuring reliable engagement of the SFA.

Application on the inclined planes of the corrugation tabs allows for increased friction between the flattened guide channels and the gripping tabs, thereby improving the reliability of the SFA engagement.

The use of a pneumatic cylinder rod as a drive with reciprocating movement, with pneumatic throttles with check valves installed in its connecting ports, allows for remote mixing and spreading of the gripping legs, thereby ensuring remote SFA engagement with the device gripper and uncoupling of the SFA after installing the SFA in the storage case defective assemblies. Installation of pneumatic throttles with check valves in the connecting ports of the pneumatic cylinder allows the supply of compressed air through the check valves to the corresponding cavities of the pneumatic cylinder in full, and by throttling the displaced air from another cavity to ensure uniform piston movement at the required speed, including at low speeds and at variable load. When moving the movable legs, which first bend the guide channels, and then flatten them, the load will change, and the speed of the piston will remain uniform, which prevents shock loads on the guide channels and possible cracking in them.

The proposed device for lifting and moving spent fuel assemblies is illustrated by the drawings presented in figure 1, figure 2 and figure 3.

In Fig.1 shows a device that engages a SFA without a head, placed in one of the hexagonal pipes of the transport cover, Fig.2 - capture with a hooked SFA for the guide channels, Fig.3 - section aa in Fig.2.

The proposed device (see Fig. 1) is located in the receiving pool 1 (SFA overload compartment) and is serviced with a movable platform 2 with a running gear installed above the receiving pool 1. The proposed device contains a rod 3, hung on the hook of a lifting device (crane), in the lower part of which is attached a protective cup 4, made in the form of two parallel plates 5 connected by a jumper 6. An air cylinder 7 is attached to the jumper 6, used as a capture drive 8 To control the pneumatic cylinder 7, a pneumatic distributor 9 is installed in the upper part of the rod 3, connected to it by tubes 10. Standard pneumatic throttles 11 with integrated valves are installed on the connecting ports of the pneumatic cylinder 7 (see FIG. 2) these check valves.

The capture 8 (see figure 2 and figure 3) contains a vertical rack 12, mounted on the jumper 6 on both sides. Between the uprights 12 in the lower part fixed legs 13 with inclined planes 14 are fixed.

The fixed legs 13 are interconnected at the ends by ribs 15. To each of the plates 5 are attached ribs 16 with inclined grooves 17 in which the movable legs 18 are mounted. On the movable legs 18, trunnions of round 19 and square 20 sections are made at their ends. The trunnion pins 20 are mounted in inclined slots 17, and the trunnion pins 19 are mounted in articulated rods 21. The articulated rods 21 are also pivotally mounted on axles 22 attached to the traverse 23 mounted on the rod of the pneumatic cylinder 7.

The proposed device for lifting and moving spent fuel assemblies works as follows.

The device is lowered by a crane into the receiving pool 1 and using a movable platform 2 is placed above the cell transport cover, in which there is a defective SFA without a head. The gripper 8 is inserted into the hexagonal tube of the transport cover until the fixed legs 13 come in contact with the upper spacer grids of the SFA, while in parallel plates 5 it is centered on the faces of the hexagonal tube. As a result of this centering, the fixed legs 13 and the movable legs 18, which are in the upper position, are placed on opposite sides of the extreme rows of the SFA guide channels. The pneumatic distributor 9 through one of the tubes 10 supplies compressed air to the pneumatic cylinder 7, extending its rod with a traverse 23, connected by articulated rods 21 with movable legs 18. Under the action of the pneumatic cylinder 7, the movable legs 18 are moved by their axles 20 of square cross section along inclined grooves 17, normal to the inclined planes 14 of the fixed legs 13, bending and flattening the guide channels, and as a result, the flattened guide channels are clamped between the movable 18 and the fixed 13 legs.

When testing the device, the speed of movement of the rod of the pneumatic cylinder 7 and associated kinematically movable legs 18 is adjusted by pneumatic throttles 11, regulating the flow of air displaced from the cavities of the pneumatic cylinder 7.

After engagement, the SFA is removed from the hexagonal tube of the transport cover and lowered into a special cover designed to store the defective SFA, after which the air distributor 9 feeds air into the other cavity of the pneumatic cylinder 7, when the rod is retracted, the movable legs 18 rise, as a result of which the gripper 8 is disengaged from the SFA installed in the case.

Claims (3)

1. A device for lifting and moving spent fuel assemblies, comprising a receiving basin, a movable platform with a running gear installed above the receiving basin, a lifting device, a protective cup having a cavity open from the side of the pool, a grip mounted in a cavity of the protective cup attached to the bottom rod mounted on the lifting device, the actuator with reciprocating movement of the rod located in the cavity of the protective glass, characterized in that the grip is provided with Vision and movable tabs, fixed legs attached to the protective glass, the movable legs connected by hinge rods to traverse mounted on the drive rod, and are mounted in inclined slots of the guide ribs attached to the protective glass and directed along the normal to the fixed tabs. 2. The device according to claim 1, characterized in that the supporting surfaces of the movable and fixed legs are made in the form of inclined planes with the same angle of inclination, and corrugation is applied to the inclined planes. 3. The device according to claim 1, characterized in that a pneumatic cylinder is used as a actuator with a reciprocating motion of the rod, pneumatic throttles with check valves are installed in the connecting ports thereof.

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