阅读说明：本技术 一种铅基反应堆燃料组件的下管座浮力锁紧机构 (Lower pipe seat buoyancy locking mechanism of lead-based reactor fuel assembly ) 是由 盛鑫 顾龙 于锐 朱彦雷 刘璐 王大伟 李金阳 彭天骥 张璐 唐延泽 秦长平 于 2019-10-10 设计创作，主要内容包括：本发明涉及一种铅基反应堆燃料组件的下管座浮力锁紧机构,包括：堆芯栅格板,其上开设有贯穿孔洞,该孔洞内壁沿周向开有若干个锁紧槽；下管座,用于定位插入堆芯栅格板的孔洞中,下管座在插入堆芯栅格板的区域内沿周向开设有若干个球锚孔；浮动滑筒,同轴设置在下管座内并能够随浮力进行竖直轴向移动,浮动滑筒的下部外壁面上形成有多段滑槽；球锚,若干个球锚分别限制于下管座的球锚孔与浮动滑筒的多段滑槽之间,并仅可沿下管座的球锚孔进行水平轴向移动。本发明通过浮力使球锚在浮动滑筒的多段滑槽推动下,通过下管座通孔被外推卡入堆芯栅格板的锁紧槽,由此球锚以挡销的形式位于堆芯栅格板、下管座及浮动滑筒之间,限制三者相互移动。(The invention relates to a lower pipe seat buoyancy locking mechanism of a lead-based reactor fuel assembly, which comprises: the reactor core grid plate is provided with a through hole, and the inner wall of the through hole is provided with a plurality of locking grooves along the circumferential direction; the lower pipe seat is used for being positioned and inserted into the hole of the reactor core grid plate, and a plurality of ball anchor holes are formed in the lower pipe seat along the circumferential direction in the region inserted into the reactor core grid plate; the floating sliding cylinder is coaxially arranged in the lower pipe seat and can vertically and axially move along with buoyancy, and a plurality of sections of sliding grooves are formed on the outer wall surface of the lower part of the floating sliding cylinder; and the ball anchors are respectively limited between the ball anchor holes of the lower pipe seat and the multi-section sliding grooves of the floating sliding cylinder and can only move horizontally and axially along the ball anchor holes of the lower pipe seat. The ball anchor is pushed by the multi-section sliding grooves of the floating sliding cylinder through buoyancy and pushed outwards through the through hole of the lower pipe seat to be clamped into the locking groove of the reactor core grid plate, so that the ball anchor is positioned among the reactor core grid plate, the lower pipe seat and the floating sliding cylinder in a stop pin mode to limit the mutual movement of the three.)

1. A lower tube seat buoyancy locking mechanism of a lead-based reactor fuel assembly, comprising:

the reactor core grid plate (5) is provided with a through hole, and the inner wall of the hole of the reactor core grid plate (5) is provided with a plurality of locking grooves along the circumferential direction;

the lower pipe seat (2) is a cylindrical shell, forms the outer boundary of the lower pipe seat buoyancy locking mechanism (100), and is used for being positioned and inserted into the hole of the reactor core grid plate (5), and a plurality of ball anchor holes are formed in the lower pipe seat (2) along the circumferential direction in the region where the reactor core grid plate (5) is inserted;

the floating sliding cylinder (7) is a variable cross-section cylinder body, is coaxially arranged in the lower pipe seat (2) and can move vertically and axially along with buoyancy, and a plurality of sections of sliding grooves are formed in the outer wall surface of the lower part of the floating sliding cylinder (7);

the ball anchors (6) are limited between the ball anchor holes of the lower pipe seat (2) and the multi-section sliding grooves of the floating sliding barrel (7) respectively, and can only move horizontally and axially along the ball anchor holes of the lower pipe seat (2).

2. The lower tube seat buoyancy locking mechanism according to claim 1, wherein a plurality of ball anchor holes are arranged at equal angular intervals along the circumferential direction of the lower tube seat (2), the diameter of each ball anchor hole is slightly larger than the diameter of the ball anchor (6), the diameter of the ball anchor (6) is about three times of the wall thickness of the lower tube seat (2), the outer side edges of the ball anchor holes are inward arc-shaped closed ends, and the radian of the arc-shaped closed ends is matched with the surface of the ball anchor (6) so as to prevent the ball anchor (6) from falling out of the lower tube seat (2) when the ball anchor (6) moves horizontally and axially along the ball anchor holes.

3. The lower nozzle buoyancy locking mechanism according to claim 1, wherein a limiting boss is formed on the outer wall surface of the lower nozzle (2), and the diameter of the limiting boss is larger than the hole diameter of the grid plate (5) of the reactor core, so as to restrict the downward insertion depth of the lower nozzle (2).

4. The lower pipe seat buoyancy locking mechanism is characterized in that the lower pipe seat buoyancy locking mechanism further comprises push rods (1), and the lower ends of the push rods (1) are connected with a floating sliding barrel (7).

5. The lower pipe seat buoyancy locking mechanism is characterized in that the inner cavity of the floating sliding cylinder (7) is a through hole with the same diameter, the upper wall surface and the lower wall surface of the floating sliding cylinder (7) are thicker, and the middle wall surface is thinner.

6. The lower pipe seat buoyancy locking mechanism is characterized in that a plurality of threaded openings which are annularly arranged at equal angular intervals are formed in the upper end face of the floating sliding cylinder (7) and are used for being connected with the lower end of the push rod (1).

7. The lower pipe seat buoyancy locking mechanism of claim 1, wherein the multi-section chute is divided into 5 sections from top to bottom: the first section is a first vertical sliding groove (I), the second section is a slope sliding groove (II), the third section is a transition sliding groove (III), the fourth section is a second vertical sliding groove (IV), the fifth section is a spherical groove (V), and the diameter of the spherical groove (V) is equal to that of the ball anchor (6).

8. The lower tube seat buoyancy locking mechanism according to claim 1, characterized in that a guide support ring (3) is formed on the inner wall surface of the lower tube seat (2), and the inner wall surface of the guide support ring (3) is in contact with the upper outer wall surface of the floating slide cylinder (7) and forms a sliding pair to radially support the floating slide cylinder (7).

9. The lower nozzle buoyancy locking mechanism according to claim 1, characterized in that the lower baffle ring (4) is further formed on the inner wall surface of the lower nozzle (2) below the floating sliding cylinder (7) for limiting the vertical downward movement distance of the floating sliding cylinder (7).

Technical Field

The invention relates to a reactor fuel assembly, in particular to a lower pipe seat buoyancy locking mechanism of a lead-based reactor fuel assembly, which can complete locking on a reactor core grid plate.

Background

The lead-based reactor is a fast neutron reactor which takes molten lead or lead-bismuth alloy as a coolant, adopts closed fuel circulation and can operate under the conditions of normal pressure and high temperature. The lead-based reactor has excellent fuel conversion capacity, can effectively improve the utilization rate of uranium and thorium resources, improves the sustainability of the fuel, and can be used for incinerating long-life actinides in the conventional light water reactor spent fuel, thereby more cleanly utilizing nuclear energy. In addition, the inert and low pressure coolant system in the lead-based reactor further enhances the safety of the reactor.

The lead and lead bismuth alloy is characterized in that: lead and lead bismuth alloy are solid at normal temperature, the melting point of lead is 327.5 ℃, the melting point of lead bismuth alloy is 125 ℃, and the lead-based reactor coolant needs to melt and flow at high temperature; lead oxide of a solid substance is generated after the lead solution is contacted with air, and if the lead oxide flows along with liquid lead, equipment in a reactor can be damaged and blocked; the content of oxygen in the lead-bismuth alloy melt needs to be controlled to reduce corrosion to the metal materials in the reactor, and the bismuth element and the neutron in the lead-bismuth alloy melt react to generate trace amount of polonium (P-210). Therefore, the lead-based reactor must maintain high heat preservation and sealing, and an effective treatment and purification system is adopted to ensure the environment and personnel safety, so that the lead-based reactor needs an in-reactor refueling mode different from the traditional pressurized water reactor uncapping refueling mode. However, the fuel assemblies in the in-core refueling mode are not provided with an upper part pressing and fixing device, but are fixed on the grid plate of the reactor core by designing a locking mechanism, and when refueling, a refueling machine is needed to unlock the locking mechanism of the fuel assemblies and is fixedly connected with the upper end seats of the fuel assemblies, and then the fuel assemblies are lifted out of the reactor core.

As is well known, lead has a density of 11.34g/cm³The density of the lead-bismuth alloy is 10.5g/cm³The density of the steel material is 7.9g/cm³Since the average density of the fuel assembly made of steel material is lower than that of the lead-based coolant (for convenience of description, the lead melt and the lead-bismuth alloy melt are collectively referred to as the lead-based coolant), the fuel assembly is subjected to upward buoyancy when immersed in the lead-based coolant, and cannot be placed in the lead-based reactor. To address this problem, two approaches are generally used in existing fuel assembly designs: the first method is to add a counterweight made of tungsten or depleted uranium at the upper part or the lower part of the fuel assembly, the density of the two metals is higher than that of a lead-based coolant, so that the fuel assembly can be inserted into the holes of the grid plate of the reactor core against buoyancy, but the addition of the counterweight can influence the flow channel design inside the fuel assembly; second oneA locking mechanism is designed on a lower tube seat of a fuel assembly, and after the lower tube seat is inserted into a hole of a reactor core grid plate, the locking mechanism is started to fix the fuel assembly on the reactor core grid plate. Because the fuel assembly is fixed on the reactor core grid plate by only depending on the locking mechanism, the buoyancy of the lead-based coolant can generate larger load on the locking mechanism, and the reliability of the locking mechanism is reduced, the balance weight and the locking mechanism are used simultaneously in the current domestic and foreign design, so that the fuel assembly is stably fixed on the reactor core grid plate. Since the locking mechanism of the fuel assembly is mostly a moving part, and the lead-based coolant environment is complex, the corrosion and erosion effects on the fuel assembly are large, and the moving part can be blocked by lead oxide and corrosion products. Therefore, the simplicity and reliability of the locking mechanism are very important, and a proper locking mechanism must be adopted to ensure that the fuel assemblies are effectively fixed on the reactor core grid plate under normal working conditions and other working conditions and realize flexible refueling.

Currently, the known design of fuel assemblies in lead-based reactors using locking mechanisms is the european union's XADS scheme. In the scheme, the lower pipe seat of the fuel assembly is internally provided with the reed type locking mechanism, a fuel rod at the center of the fuel assembly is drawn out, then a push rod is placed in the fuel rod, the upper part of the push rod is connected with the upper pipe seat transmission mechanism, and the lower part of the push rod is connected with the reed chuck in the lower pipe seat. The upper tube seat is under the action of the refueling machine grabbing head pushing mechanism, so that the push rod can move up and down, the push rod drives the reed clamping head to elastically deform and extend out of the lower tube seat outer sleeve of the fuel assembly, and then the reed clamping head is clamped with the lower surface of the reactor core grid plate, so that the fuel assembly is locked. However, the reed chuck of the reed type locking mechanism is thin and difficult to bear the long-term corrosion and erosion effects of the lead-based coolant, and meanwhile, under the high irradiation environment of the lead-based reactor, the material of the reed type locking mechanism can be subjected to irradiation embrittlement, so that the reed type locking mechanism is extremely easy to break, and the reliability of the scheme needs to be evaluated.

There are also known designs of fuel assemblies in lead-based reactors using locking mechanisms, and refill lifting solutions similar to automatic ball-point pens. Specifically, in a locking state, the locking mechanism is clamped in the circumferential tooth groove by virtue of self buoyancy; when unlocking is carried out, the lifting mechanism pushes the fuel assembly downwards, so that the locking sliding block slides to an unlocking position along the circumferential tooth groove, and therefore unlocking is achieved. Although the locking mechanism utilizes the characteristic of larger buoyancy of the liquid lead-bismuth alloy, the fuel assembly is not locked in the true sense, the fuel assembly still has the possibility of moving up and down, and particularly the fuel assembly is easy to move up and down under the earthquake working condition, so that the locking slide block slides to the unlocking position, and the fuel assembly is unlocked.

As described above, the conventional fuel assembly is difficult to withstand the combined effects of high temperature, high corrosion, high irradiation environment in the reactor and seismic load of the liquid lead-bismuth coolant in the lead-based reactor. Therefore, it is desirable to design and develop fuel assemblies that are more reliable, easier to operate, and more fully utilize the high buoyancy characteristics of liquid lead bismuth alloys.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide a lower tube support buoyancy locking mechanism of a lead-based reactor fuel assembly, which can achieve a locking function on a reactor core grid plate easily.

In order to achieve the purpose, the invention adopts the following technical scheme: a lower tube seat buoyancy lock mechanism for a lead-based reactor fuel assembly, comprising: the reactor core grid plate is provided with a through hole, and the inner wall of the hole of the reactor core grid plate is provided with a plurality of locking grooves along the circumferential direction; the lower pipe seat is a cylindrical shell, forms the outer boundary of the lower pipe seat buoyancy locking mechanism, and is used for being positioned and inserted into the hole of the reactor core grid plate, and a plurality of ball anchor holes are formed in the lower pipe seat along the circumferential direction in the region where the lower pipe seat is inserted into the reactor core grid plate; the floating sliding cylinder is a variable cross-section cylinder body, is coaxially arranged in the lower pipe seat and can vertically and axially move along with buoyancy, and a plurality of sections of sliding grooves are formed in the outer wall surface of the lower part of the floating sliding cylinder; and the ball anchors are respectively limited between the ball anchor holes of the lower pipe seat and the multi-section sliding grooves of the floating sliding cylinder and can only horizontally and axially move along the ball anchor holes of the lower pipe seat.

The lower tube seat buoyancy locking mechanism is preferably characterized in that a plurality of ball anchor holes are arranged along the annular direction of the lower tube seat at equal angular intervals, the diameter of each ball anchor hole is slightly larger than that of the ball anchor, the diameter of the ball anchor is about three times of the wall thickness of the lower tube seat, the outer side edge of each ball anchor hole is inward arc-shaped closed, the radian of the arc-shaped closed is matched with the surface of the ball anchor, and the ball anchor is prevented from falling out of the lower tube seat when moving horizontally and axially along the ball anchor holes.

Preferably, the lower pipe seat buoyancy locking mechanism is characterized in that a limiting boss is formed on the outer wall surface of the lower pipe seat, the diameter of the limiting boss is larger than that of the hole of the reactor core grid plate, and the limiting boss is used for limiting the downward insertion depth of the lower pipe seat.

The lower pipe seat buoyancy locking mechanism preferably further comprises push rods, and the lower ends of the push rods are connected with the floating sliding cylinders.

Preferably, the inner cavity of the floating sliding cylinder is a through hole with equal diameter, the upper wall surface and the lower wall surface of the floating sliding cylinder are thicker, and the middle wall surface is thinner.

Preferably, the upper end face of the floating sliding cylinder is provided with a plurality of threaded openings which are annularly arranged at equal angular intervals and are used for being connected with the lower end of the push rod.

Lower tube seat buoyancy locking mechanism, preferably, the multistage spout top-down divide into 5 sections: the first section is a first vertical sliding groove, the second section is a slope sliding groove, the third section is a transition sliding groove, the fourth section is a second vertical sliding groove, the fifth section is a spherical groove, and the diameter of the spherical groove is equal to that of the ball anchor.

Preferably, a guide support ring is formed on the inner wall surface of the lower pipe seat, and the inner wall surface of the guide support ring is in contact with the outer wall surface of the upper part of the floating sliding cylinder to form a sliding pair so as to radially support the floating sliding cylinder.

Preferably, the lower pipe seat buoyancy locking mechanism is further provided with a lower baffle ring on an inner wall surface of the lower pipe seat below the floating sliding cylinder, and the lower baffle ring is used for limiting a vertical downward movement distance of the floating sliding cylinder.

Due to the adoption of the technical scheme, the invention has the following advantages: 1. the invention fully utilizes the characteristic of high density of the liquid lead-bismuth alloy, and the fuel assembly is firmly locked on the reactor core grid plate by utilizing buoyancy and the lower pipe seat buoyancy locking mechanism, so that the fuel assembly is safer and more reliable than the circumferential tooth groove structure in the prior art. 2. The invention adopts a ball anchor buoyancy locking method, the ball anchor is pushed by a plurality of sections of chutes of a floating sliding barrel through buoyancy and is pushed out through a lower pipe seat through hole to be clamped into a locking groove of a reactor core grid plate, so that the ball anchor is positioned among the reactor core grid plate, the lower pipe seat and the floating sliding barrel in a stop pin mode to limit the mutual movement of the three components; meanwhile, the floating slide cylinder adopts the design of a plurality of sections of slide grooves, and can be used for preventing the ball anchor from being contracted into the ball anchor hole of the lower tube seat after being extruded by the wall surface of the hole of the grid plate of the reactor core. Compared with the traditional spring type locking mechanism utilizing elastic deformation, the invention can more effectively avoid locking failure caused by corrosion, erosion and radiation embrittlement of structural materials.

Drawings

FIG. 1 is a cross-sectional view of the present invention;

FIG. 2 is a schematic view of the constraint relationship between the ball anchor and the ball anchor hole of the present invention;

FIG. 3 is an isometric view of the floating slide of the present invention;

FIG. 4 is a cross-sectional view of the floating slide of the present invention;

FIG. 5 is a view of the lead based reactor core not yet in accordance with the present invention;

FIG. 6 is a state diagram of the present invention during placement in a lead-based reactor core;

FIG. 7 is a view of the lead based reactor core after placement of the present invention;

fig. 8 is a state diagram of the lower pipe support locked to the grid plate of the core according to the present invention.

Detailed Description

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that the objects, features and advantages of the invention can be more clearly understood. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the present invention, but are merely intended to illustrate the spirit of the technical solution of the present invention.

As shown in fig. 1, the buoyancy locking mechanism for a lower tube seat of a fuel assembly of a lead-based reactor provided by the invention comprises: the reactor core grid plate 5 is characterized in that a through hole is formed in the reactor core grid plate 5, and a plurality of locking grooves are formed in the inner wall of the hole of the reactor core grid plate 5 along the circumferential direction; the lower pipe seat 2 is a cylindrical shell and forms the outer boundary of the lower pipe seat buoyancy locking mechanism 100 and is used for being positioned and inserted into the hole of the reactor core grid plate 5, and a plurality of ball anchor holes are formed in the lower pipe seat 2 along the circumferential direction in the region where the reactor core grid plate 5 is inserted; the floating sliding cylinder 7 is a variable cross-section cylinder body, is coaxially arranged in the lower pipe seat 2 and can vertically and axially move along with buoyancy, and a plurality of sections of sliding grooves are formed on the outer wall surface of the lower part of the floating sliding cylinder 7; the ball anchor 6 and the ball anchors 6 are respectively limited between the ball anchor hole of the lower pipe seat 2 and the multi-section sliding groove of the floating sliding barrel 7 and can only move along the ball anchor hole of the lower pipe seat 2 in the horizontal axial direction. Thus, the lower nozzle buoyancy locking mechanism 100 moves the floating slide 7 upward by buoyancy to push the ball anchor 6 out of the ball anchor hole of the lower nozzle 2 and fit into the locking groove of the grid plate 5, so that the ball anchor 6 restricts the mutual displacement of the lower nozzle 2 and the grid plate 5 by a stopper pin, thereby locking the lower nozzle 2 to the grid plate 5.

In the above embodiment, preferably, as shown in fig. 1 and fig. 2, the plurality of ball anchor holes are arranged at equal angular intervals along the circumferential direction of the lower socket 2, the diameter of each ball anchor hole is slightly larger than the diameter of the ball anchor 6, the diameter of the ball anchor 6 is about three times of the wall thickness of the lower socket 2, the outer edges of the ball anchor holes are inward arc-shaped closed ends, and the radian of the arc-shaped closed ends is matched with the surface of the ball anchor 6, so that the ball anchor 6 can be prevented from falling out of the lower socket 2 when moving along the horizontal axial direction of the ball anchor holes.

In the above embodiment, it is preferable that a limit boss is formed on an outer wall surface of the lower nozzle 2, and a diameter of the limit boss is larger than a diameter of the hole of the grid plate 5 for restricting a downward insertion depth of the lower nozzle 2.

In the above embodiment, preferably, the lower pipe seat buoyancy locking mechanism further includes push rods 1, and the lower ends of the push rods 1 are connected to the floating sliding cylinder 7.

In the above embodiment, preferably, as shown in fig. 3 and 4, the inner cavity of the floating slide 7 is a through hole with an equal diameter, and the upper and lower wall surfaces of the floating slide 7 are thicker and the middle wall surface is thinner.

In the above embodiment, preferably, the upper end surface of the floating sliding barrel 7 is provided with a plurality of threaded openings arranged circumferentially at equal angular intervals for connecting with the lower end of the push rod 1.

In the above embodiment, preferably, the multi-section chute is divided into 5 sections from top to bottom: the first section is a first vertical sliding groove I, the second section is a slope sliding groove II, the third section is a transition sliding groove III, the fourth section is a second vertical sliding groove IV, the fifth section is a spherical groove V, and the diameter of the spherical groove V is equal to that of the ball anchor 6.

In the above embodiment, preferably, as shown in fig. 2, the guide support ring 3 is formed on the inner wall surface of the bottom nozzle 2, and the inner wall surface of the guide support ring 3 contacts with the upper outer wall surface of the floating slide cylinder 7 to form a sliding pair so as to radially support the floating slide cylinder 7.

In the above embodiment, it is preferable that a lower stopper ring 4 for limiting a vertical downward moving distance of the floating slide 7 is further formed on an inner wall surface of the lower nozzle 2 located below the floating slide 7.

When the buoyancy locking mechanism 100 is used, the buoyancy locking process of the lower pipe seat buoyancy locking mechanism 100 is as follows:

when the fuel assembly is not placed in the lead-based reactor core, the floating sliding barrel 7 moves downwards to the upper surface of the lower retaining ring 4 under the action of gravity, then an axial downward thrust is transmitted through the refueling grabbing head mechanism 300, and then is transmitted to the floating sliding barrel 7 through the push rod 1, so that the floating sliding barrel 7 is pressed on the lower retaining ring 4, and the thrust is greater than the buoyancy of the floating sliding barrel 7 and the push rod 1 in the lead-based coolant. At this time, the ball anchor 6 is located in a space formed by the first vertical sliding groove i of the floating sliding cylinder 7 and the ball anchor hole of the lower socket 2, and the space can make the ball anchor 6 shrink in the ball anchor hole of the lower socket 2, so that the ball anchor 6 does not bear any external load (the state is shown in fig. 5).

When the fuel assembly is inserted into the lead-based reactor core, the fuel assembly can be sunk into the lead-based coolant due to the counterweight inside the fuel assembly, and the floating slide 7 cannot float upwards due to the previously applied downward thrust. After the lower pipe seat 2 is inserted into the hole of the reactor core grid plate 5 to a certain depth, the limiting boss outside the lower pipe seat 2 is clamped on the upper surface of the hole of the reactor core grid plate 5 to prevent the lower pipe seat 2 from continuously sinking, and meanwhile, the ball anchor 6 corresponds to the locking groove position on the reactor core grid plate 5. At this time, the thrust is removed from the material changing gripper mechanism 300, the floating slide cylinder 7 starts to float upwards under the buoyancy action of the lead-based coolant, when the ball anchor 6 contacts the slope slide groove ii of the multi-section slide groove, the slope slide groove ii gradually applies an outward thrust to the ball anchor 6, and the ball anchor 6 gradually starts to be pushed out of the ball anchor hole from the state of being retracted into the ball anchor hole (the state is shown in fig. 6). When the transition chute iii of the multi-stage chute slides smoothly over the ball anchor 6, the ball anchor 6 contacts the second vertical chute iv of the multi-stage chute, and at this time, the outer portion of the ball anchor 6 is pushed out of the ball anchor hole and is fitted into the locking groove of the grid plate 5 of the core (this state is shown in fig. 7).

The floating sliding cylinder 7 continues to float upwards, and when the ball anchor 6 is in contact with the spherical surface groove V of the multi-section sliding groove, the ball anchor 6 blocks the floating sliding cylinder 7 so that the floating sliding cylinder is not floated upwards any more. At this time, the ball anchor 6 penetrates the ball anchor hole of the lower socket 2, and is circumferentially constrained by the wall surface of the ball anchor hole, and if the ball anchor 6 moves outward in the axial direction of the ball anchor hole, it is hindered by the arc-shaped closing-up of the outer edge of the ball anchor hole. When the ball anchor 6 is extruded by the wall surface of the locking groove on the grid plate 5 of the reactor core, the ball anchor 6 can axially retract along the ball anchor hole of the lower tube seat 2, a vertical extrusion force acts on the second vertical chute IV of the multi-section chute, and the floating slide cylinder 7 cannot generate any upward or downward thrust, and due to the constraint action of the guide support ring 3, the floating slide cylinder 7 cannot move in the radial direction, so that the axial retraction of the ball anchor 6 along the ball anchor hole is also constrained. Under the action of buoyancy, the spherical grooves v of the multi-segment chute always keep applying an upward thrust to the lower surface of the ball anchor 6, so that the position of the ball anchor 6 is locked by the buoyancy, the ball anchor 6 at the position is positioned among the hole of the grid plate 5 of the core, the ball anchor hole of the lower tube base 2 and the floating slide 7, and the mutual movement between the grid plate 5 of the core and the lower tube base 2 is limited in the form of a stop pin, so that the lower tube base 2 is locked on the grid plate 5 of the core by the buoyancy (this state is shown in fig. 8).

The above embodiments are only used for illustrating the present invention, and the structure, connection mode, manufacturing process, etc. of the components may be changed, and all equivalent changes and modifications performed on the basis of the technical solution of the present invention should not be excluded from the protection scope of the present invention.