Buffer for cushioning the drop impact of control rods in high-temperature molten salt reactors

Abstract

The present invention discloses a buffer for buffering the dropping impact of a control rod of a high-temperature molten salt reactor. The buffer includes an outer guide member, a piston member, a reset member, and a plurality of small balls. The piston member is placed inside the outer guide member. The inner peripheral surface of the outer guide member cooperates with the outer peripheral surface of the piston member. A cavity is formed between the inner peripheral surface of the outer guide member and the outer peripheral surface of the piston member. The inner peripheral surface of the outer guide member has a protrusion, and the protrusion is located inside the cavity. The piston member can move downward inside the outer guide member when the control rod drops. The reset member is located inside the outer guide member and below the piston member, and the reset member always applies an upward force to the piston member. The small balls are filled in the cavity. In the present invention, the small balls and the reset member jointly buffer the downward impact energy of the control rod, reducing the impact on the base. When the reset member resets, the rebound height of the control rod is reduced. After the reset member resets, no permanent deformation is caused to the buffer, so it can be reused.

Description

Technical Field

[0001] The present invention relates to a buffer, and more particularly to a buffer for buffering the drop impact of a control rod in a high-temperature molten salt reactor. Background Art

[0002] The control rod drive mechanism is an important device for starting, stopping, and power regulating a high-temperature molten salt reactor. The control rod operates in the thin-walled pressure vessel casing of the graphite reflector around the core of the molten salt reactor. When an extreme fracture accident occurs in the transmission chain of the control rod drive mechanism, the control rod will fall freely from a relatively high position above the active area of the reactor. When it falls to the bottom of the channel, the maximum speed it may reach is more than 10 m / s. The high-speed fall of the rod body will cause impact damage to the pressure vessel casing, and the pressure vessel casing is welded integrally with the reactor vessel and belongs to the primary loop pressure boundary, thus leading to the leakage of radioactive substances. Therefore, a buffer device needs to be set at the end of the control rod stroke to buffer the drop impact of the control rod and protect the structure of the pressure vessel casing from being damaged. At the same time, this buffer device needs to be able to withstand high temperatures above 600 °C and a certain amount of nuclear radiation.

[0003] The thin-walled cylinder buffer used in a high-temperature gas-cooled reactor can buffer the drop impact of the control rod, but this structure will undergo buckling deformation after the control rod drop impact and cannot be used again. At the same time, this device is installed inside the pressure vessel and is not easy to replace.

[0004] Conventional hydraulic damping buffers are restricted in use under some special working conditions. For example, in a nuclear reactor environment, the high-temperature and high-radiation environment will cause the sealing rings of the hydraulic damping buffer to age easily, and the oil fluid is also prone to deterioration and failure. On the other hand, when the hydraulic damping buffer is subjected to an impact load, a large oil pressure will be formed locally in the buffer cavity, and good sealing needs to be done, resulting in complex processing technology and high production cost. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects in the prior art that the thin-walled cylinder buffer is prone to buckling deformation, has poor reuse effect, the hydraulic buffer process is complex and good sealing needs to be done, and the sealing ring is extremely easy to age and the oil fluid is prone to deterioration and failure, etc., and to provide a buffer for buffering the drop impact of a control rod in a high-temperature molten salt reactor.

[0006] The present invention solves the above technical problems through the following technical solutions:

[0007] The present invention provides a buffer for buffering the drop impact of a control rod in a high-temperature molten salt reactor, and the buffer includes:

[0008] An outer guide member and a piston member, wherein the piston member is placed inside the outer guide member, the inner peripheral surface of the outer guide member is matched with the outer peripheral surface of the piston member, a cavity is formed between the inner peripheral surface of the outer guide member and the outer peripheral surface of the piston member, and a protrusion is provided on the inner peripheral surface of the outer guide member and is located inside the cavity; the piston member can move downward inside the outer guide member when the control rod drops.

[0009] A reset member, which is located inside the outer guide member and below the piston member, and the reset member always applies an upward force to the piston member.

[0010] A plurality of small balls, which are filled in the cavity.

[0011] In this technical solution, when the control rod drops, it moves downward inside the outer guide member, presses down the piston member, and the piston member compresses the reset member, and the reset member absorbs the impact energy; the small balls act as damping media. When the control rod drops, the small balls rub against the cavity surface to reduce the descending speed of the control rod, buffer the downward impact energy of the control rod, reduce the impact on the base, and further reduce the impact on the pressure vessel nozzle, preventing damage to the pressure boundary. At the same time, when the reset member resets, the frictional force between the small balls and the inner surface of the cavity can consume the elastic potential energy and reduce the rebound height of the control rod. After the reset member resets, the buffer can reach the initial state without causing permanent deformation to the buffer, so it can be reused.

[0012] Preferably, a guide rod head is formed at the end of the control rod, and the inner peripheral surface of the piston member can be matched with the outer peripheral surface of the control rod; the protruding end surface of the piston member is in contact with the guide rod head, and the inner peripheral surface of the outer guide member is greater than or equal to the outer peripheral surface of the guide rod head.

[0013] In this technical solution, the inner peripheral surface of the outer guide member is greater than or equal to the outer peripheral surface of the guide rod head, so that when the control rod enters the outer guide member, the guide rod head can press down the piston member, and the piston member compresses the reset member, so that the buffer can buffer the control rod more effectively.

[0014] Preferably, the piston member further includes:

[0015] A shock-bearing ring, whose outer peripheral surface is matched with the inner peripheral surface of the outer guide member;

[0016] A ball-blocking ring, whose outer peripheral surface is matched with the inner peripheral surface of the outer guide member, and the upper end of the ball-blocking ring is connected to the lower end of the shock-bearing ring;

[0017] The cavity is formed by the inner peripheral surface of the outer guide member, the lower end surface of the shock-bearing ring and the outer peripheral surface of the ball-blocking ring.

[0018] In this technical solution, the piston part includes a bearing impact ring and a ball blocking ring, which facilitates the installation of the buffer and makes the operation of placing the small ball simple and convenient.

[0019] Preferably, the inner peripheral surface of the upper end of the ball blocking ring has an internal thread, the lower end of the bearing impact ring extends into the upper end of the ball blocking ring, the outer peripheral surface of the lower end of the bearing impact ring forms an external thread, and the upper end of the ball blocking ring is threadedly connected to the lower end of the bearing impact ring.

[0020] In this technical solution, the ball blocking ring and the bearing impact ring are threadedly connected, the manufacturing process of the components is simple, and the installation process is easy.

[0021] Preferably, a gap is formed between the protrusion and the outer peripheral surface of the piston part, and the width of the gap along the radial direction of the piston part is greater than the diameter of the small ball.

[0022] In this technical solution, the gap formed between the protrusion and the outer peripheral surface of the piston part allows the small ball to pass through, further reducing the radial distance for the small ball to pass through. The small ball is squeezed at the gap, and the frictional heat energy formed with the surface of the gap becomes larger, consuming the impact energy of the control rod downward to a greater extent, reducing the impact on the base, and further reducing the impact on the pressure vessel casing, preventing the destruction of the pressure boundary. At the same time, when the reset part resets, the friction between the small ball and the gap further consumes the elastic potential energy of the reset part, further reducing the rebound height of the control rod.

[0023] Preferably, the protrusion includes a protrusion end face and at least one protrusion inclined face. The protrusion end face surrounds the outer peripheral surface of the piston part along the circumferential direction of the piston part, the protrusion end face forms the gap with the outer peripheral surface of the piston part, the protrusion inclined face connects the edge of the protrusion end face and the inner peripheral surface of the outer guide part, and the protrusion inclined face forms an obtuse angle with the inner peripheral surface of the outer guide part.

[0024] In this technical solution, the protrusion inclined face of the protrusion forms an obtuse angle with the inner peripheral surface of the outer guide part, which can have a guiding effect on the small ball when it passes through the gap.

[0025] Preferably, the reset part is a compression spring. The upper surface of the compression spring is in contact with the piston part, the bottom of the compression spring is in contact with the bottom of the outer guide part, and the inner peripheral surface of the compression spring is larger than the outer peripheral surface of the control rod.

[0026] In this technical solution, the reset part is a compression spring, which has better elasticity and better reset effect; and the material of the compression spring is simple and easy to manufacture.

[0027] Preferably, the filling amount of the small balls is 2 / 3 of the volume of the cavity.

[0028] In this technical solution, the small balls fill 2 / 3 of the cavity volume. The small balls have sufficient filling quantity and space, so that when the control rod enters the buffer, the small balls can move up and down in the cavity to obtain buffering as much as possible.

[0029] Preferably, the material of the small balls is ceramic.

[0030] In this technical solution, the ceramic balls are used as damping media, which are not affected by high temperature and high radiation. At the same time, there is no need for sealing, eliminating the aging problem of the sealing ring under high temperature and high radiation, thus ensuring long-term reliable operation in a high temperature and high radiation environment.

[0031] Preferably, the diameter of the small balls is 1.2 mm.

[0032] In this technical solution, the diameter of the small balls is set to 1.2 mm, which can be easily placed in the cavity and move up and down in the cavity.

[0033] The positive and progressive effects of the present invention are as follows:

[0034] In the present invention, when the control rod drops, it moves downward in the outer guide member, presses down the piston member, and the piston member compresses the reset member, and the reset member absorbs the impact energy; the small balls are used as damping media. When the control rod drops, the small balls rub against the cavity surface to reduce the descending speed of the control rod, buffer the impact energy of the control rod downward, reduce the impact on the base, and further reduce the impact on the pressure vessel casing, preventing damage to the pressure boundary. When the reset member resets, the frictional force between the small balls and the inner surface of the cavity can consume the elastic potential energy and reduce the rebound height of the control rod. After the reset member resets, the buffer can reach the initial state without causing permanent deformation to the buffer, so it can be reused. Description of the Drawings

[0035] Figure 1 It is a cross-sectional view of the buffer of the embodiment of the present invention when not pressed by the control rod.

[0036] Figure 2 It is a cross-sectional view of the buffer of the embodiment of the present invention when just contacting the control rod.

[0037] Figure 3 It is a cross-sectional view of the buffer of the embodiment of the present invention when pressed by the control rod.

[0038] Figure 4 is Figure 1 a partial enlarged view of part A in

[0039] Description of the Reference Numerals:

[0040] Control rod 100

[0041] Guide rod head 200

[0042] Outer guide member 1

[0043] Outer guide cylinder 11

[0044] Base 12

[0045] Piston part 2

[0046] Impact bearing ring 21

[0047] Ball retaining ring 22

[0048] Reset part 3

[0049] Small ball 4

[0050] Cavity 5

[0051] Protrusion 6

[0052] Protrusion end face 61

[0053] Protrusion inclined surface 62 Specific implementation mode

[0054] The present invention will be further described below by way of embodiments, but the present invention is not limited to the scope of the described embodiments.

[0055] As Figures 1 to 4 shown, this embodiment discloses a buffer for buffering the drop impact of the control rod 100 of a high-temperature molten salt reactor, which includes: an outer guide member 1, a piston member 2, a reset member 3, and a plurality of small balls 4. The piston member 2 is placed inside the outer guide member 1. The inner peripheral surface of the outer guide member 1 cooperates with the outer peripheral surface of the piston member 2. A cavity 5 is formed between the inner peripheral surface of the outer guide member 1 and the outer peripheral surface of the piston member 2. The inner peripheral surface of the outer guide member 1 has a protrusion 6, and the protrusion 6 is located inside the cavity 5. The piston member 2 can move downward inside the outer guide member 1 when the control rod 100 drops. An attracting rod head 200 is formed at the end of the control rod 100. The inner peripheral surface of the piston member 2 can cooperate with the outer peripheral surface of the control rod 100. The protrusion end face 61 of the piston member 2 contacts the attracting rod head 200, and the inner peripheral surface of the outer guide member 1 is greater than or equal to the outer peripheral surface of the attracting rod head 200. The reset member 3 is located inside the outer guide member 1, and the reset member 3 is located below the piston member 2. The reset member 3 always applies an upward force to the piston member 2. Preferably, the reset member 3 is a compression spring. The upper surface of the compression spring contacts the piston member 2, and the bottom of the compression spring contacts the bottom of the outer guide member 1. The inner peripheral surface of the compression spring is greater than the outer peripheral surface of the control rod 100. The small balls 4 are filled in the cavity 5. Preferably, the filling amount of the small balls 4 is 2 / 3 of the volume of the cavity 5. The material of the small balls 4 is ceramic, and the diameter of the small balls 4 is 1.2 mm.

[0056] The outer guide member 1 includes an outer guide cylinder 11 and a base 12, and the outer guide cylinder 11 and the base 12 are connected by bolts. When the control rod 100 drops, it moves downward within the outer guide member 1. The pilot rod head 200 presses down the piston member 2, and the piston member 2 compresses the reset member 3 on the base 12. The reset member 3 absorbs the impact energy. At this time, the small balls 4, as damping media, friction with the surface of the cavity 5, reducing the descending speed of the control rod 100, buffering the downward impact energy of the control rod 100, reducing the impact on the base 12, and further reducing the impact on the pressure vessel casing to prevent damage to the pressure boundary. When the reset member 3 starts to reset, the frictional force between the small balls 4 and the inner surface of the cavity 5 can consume the elastic potential energy and reduce the rebound height of the control rod 100. After the reset member 3 resets, the buffer can reach the initial state without causing permanent deformation to the buffer, so it can be reused. The inner peripheral surface of the outer guide member 1 is greater than or equal to the outer peripheral surface of the pilot rod head 200, so that when the control rod 100 enters the outer guide member 1, the pilot rod head 200 can press down the piston member 2, and the piston member 2 compresses the reset member 3, enabling the buffer to more effectively buffer the control rod 100. Preferably, the reset member 3 is a compression spring, the compression spring is in contact with the base 12 of the outer guide member 1, the small balls 4 fill 2 / 3 of the volume of the cavity 5, and the small balls 4 have sufficient filling amount and space so that when the control rod 100 enters the buffer, the small balls 4 can move up and down within the cavity 5 to obtain buffering as much as possible. The reset member 3 being a compression spring has better elasticity and better reset effect; and the material of the compression spring is simple and easy to manufacture.

[0057] The material of the small balls 4 is ceramic. The ceramic balls, as damping media, are not affected by high temperature and high radiation. At the same time, there is no need for sealing, eliminating the aging problem of the sealing ring under high temperature and high radiation, thus ensuring reliable long-term operation in a high temperature and high radiation environment. The diameter of the small balls 4 is set to 2 mm, which can be easily placed in the cavity 5 and move up and down in the cavity 5.

[0058] In this embodiment, the piston member 2 further includes: a shock-bearing ring 21, the outer peripheral surface of the shock-bearing ring 21 is matched with the inner peripheral surface of the outer guide member 1; a ball-blocking ring 22, the outer peripheral surface of the ball-blocking ring 22 is matched with the inner peripheral surface of the outer guide member 1, and the upper end of the ball-blocking ring 22 is connected to the lower end of the shock-bearing ring 21; the inner peripheral surface of the outer guide member 1, the lower end surface of the shock-bearing ring 21, and the outer peripheral surface of the ball-blocking ring 22 form the cavity 5. The inner peripheral surface of the upper end of the ball-blocking ring 22 has internal threads, the lower end of the shock-bearing ring 21 extends into the upper end of the ball-blocking ring 22, the outer peripheral surface of the lower end of the shock-bearing ring 21 forms external threads, and the upper end of the ball-blocking ring 22 and the lower end of the shock-bearing ring 21 are threadedly connected.

[0059] The piston member 2 includes a bearing impact ring 21 and a ball retaining ring 22. The upper end of the ball retaining ring 22 is connected to the lower end of the bearing impact ring 21, facilitating the installation of the buffer and making the operation of placing the small ball 4 simple and convenient. The upper end of the ball retaining ring 22 and the lower end of the bearing impact ring 21 are threadedly connected, with the manufacturing process of the components being simple and the installation process being easy.

[0060] As Figure 4 shown, a gap is formed between the protrusion 6 and the outer peripheral surface of the piston member 2. The width of the gap along the radial direction of the piston member 2 is greater than the diameter of the small ball 4. The protrusion 6 includes a protrusion end face 61 and at least one protrusion inclined surface 62. The protrusion end face 61 surrounds the piston member 2 in the circumferential direction, and a gap is formed between the protrusion end face 61 and the outer peripheral surface of the piston member 2. The protrusion inclined surface 62 connects the edge of the protrusion end face 61 and the inner peripheral surface of the outer guide member 1, and the protrusion inclined surface 62 forms an obtuse angle with the inner peripheral surface of the outer guide member 1.

[0061] The gap formed between the protrusion 6 and the outer peripheral surface of the piston member 2 allows the small ball 4 to pass through, further reducing the radial distance for the small ball 4 to pass through. The small ball 4 is squeezed at the gap, and the frictional heat energy formed with the gap surface becomes larger, consuming the downward impact energy of the control rod 100 to a greater extent, reducing the impact on the base 12, and further reducing the impact on the pressure vessel casing, preventing the destruction of the pressure boundary. When the reset member 3 resets, the friction between the small ball 4 and the gap further consumes the elastic potential energy of the reset member 3, further reducing the rebound height of the control rod 100. In this technical solution, the protrusion inclined surface 62 of the protrusion 6 forms an obtuse angle with the inner peripheral surface of the outer guide member 1, which can provide a guiding effect for the small ball 4 when passing through the gap.

[0062] Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that this is only for illustration purposes. The protection scope of the present invention is defined by the appended claims. Without departing from the principles and essence of the present invention, those skilled in the art can make various changes or modifications to these embodiments, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A buffer for buffering the drop impact of the control rod of a high-temperature molten salt reactor, characterized in that, The buffer includes: An outer guide member and a piston member. The piston member is placed inside the outer guide member. The inner peripheral surface of the outer guide member cooperates with the outer peripheral surface of the piston member. A cavity is formed between the inner peripheral surface of the outer guide member and the outer peripheral surface of the piston member. The inner peripheral surface of the outer guide member has a protrusion, and the protrusion is located inside the cavity. The piston member can move downward inside the outer guide member when the control rod drops. A reset member, which is located inside the outer guide member and below the piston member. The reset member always applies an upward force to the piston member. A plurality of small balls, which are filled in the cavity. The end of the control rod forms a lead rod head. The inner peripheral surface of the piston member can cooperate with the outer peripheral surface of the control rod. The protruding end surface of the piston member contacts the lead rod head, and the inner peripheral surface of the outer guide member is larger than the outer peripheral surface of the lead rod head. The piston member further includes: A bearing impact ring, the outer peripheral surface of which cooperates with the inner peripheral surface of the outer guide member. A ball retaining ring, the outer peripheral surface of which cooperates with the inner peripheral surface of the outer guide member. The upper end of the ball retaining ring is connected to the lower end of the bearing impact ring. The inner peripheral surface of the outer guide member, the lower end surface of the bearing impact ring, and the outer peripheral surface of the ball retaining ring form the cavity. The inner peripheral surface of the upper end of the ball retaining ring has an internal thread. The lower end of the bearing impact ring extends into the upper end of the ball retaining ring. The outer peripheral surface of the lower end of the bearing impact ring forms an external thread. The upper end of the ball retaining ring and the lower end of the bearing impact ring are threadedly connected.

2. The buffer for buffering the drop impact of the control rod of a high-temperature molten salt reactor according to claim 1, characterized in that, A gap is formed between the protrusion and the outer peripheral surface of the piston member. The width of the gap along the radial direction of the piston member is larger than the diameter of the small ball.

3. The buffer for buffering the drop impact of the control rod of a high-temperature molten salt reactor according to claim 2, characterized in that, The protrusion includes a protruding end surface and at least one protruding inclined surface. The protruding end surface surrounds along the circumferential direction of the piston member. The protruding end surface and the outer peripheral surface of the piston member form the gap. The protruding inclined surface connects the edge of the protruding end surface and the inner peripheral surface of the outer guide member. The protruding inclined surface and the inner peripheral surface of the outer guide member form an obtuse angle.

4. The buffer for buffering the drop impact of the control rod of a high-temperature molten salt reactor according to claim 1, characterized in that, The reset member is a compression spring. The upper surface of the compression spring contacts the piston member. The bottom of the compression spring contacts the bottom of the outer guide member. The inner peripheral surface of the compression spring is larger than the outer peripheral surface of the control rod.

5. The buffer for buffering the drop impact of the control rod of a high-temperature molten salt reactor according to claim 1, characterized in that, The filling amount of the small balls is 2 / 3 of the volume of the cavity.

6. The buffer for buffering the drop impact of the control rod of a high-temperature molten salt reactor according to claim 1, characterized in that, The material of the small balls is ceramic.

7. The buffer for buffering the drop impact of the control rod of a high-temperature molten salt reactor according to claim 1, characterized in that, The diameter of the small balls is 1.2 mm.

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