Reactivity Control Mechanism of Small-sized Heat Pipe Reactor

Abstract

The present invention discloses a reactivity control mechanism for a small heat pipe reactor, comprising two opposing reflective side plates, each of which is a quarter-circular structure and is used to close the openings on both sides of the reactor core. The mechanism also includes an outer frame and an inner frame, which are mounted concentrically with the heat pipe reactor and are rotatable. The outer frame includes two upper and lower circular plates a, with two symmetrical uprights a fixedly connected between the edges of the two circular plates a. The circular plates a are provided with two centrally symmetrical oblique long holes. The inner frame is located between the two circular plates a. The reflective side plates are located within the inner frame and are radially slidably connected to the inner frame. Drive posts are provided at the middle of the upper and lower ends of the reflective side plates, respectively. The drive posts extend through the inner frame and are inserted into the oblique long holes. The inner frame and the heat pipe reactor are locked by an electromagnetic lock. The control mechanism has a simple structure, good stability, and is not prone to failure. It is easier to achieve the goals of miniaturization and mobility of the reactor core and can achieve reactivity control over a wide range.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear power, and specifically to a reactivity control mechanism for a small heat pipe reactor. Background Art

[0002] In nuclear power, large power reactors have problems such as complex safety mechanisms, cumbersome construction, and high costs. The small heat pipe reactor has low design and construction costs and rich application scenarios, and can supply power to a certain community in the city, a supercomputer center or a remote area, having a relatively broad market. The reactivity of a nuclear reactor is a physical quantity reflecting the state of the nuclear reactor, used to characterize the degree of deviation of the reactor from the critical state. The value of reactivity depends on the number of neutrons. Therefore, the reactivity can be controlled by controlling the leakage of neutrons.

[0003] In the design of the reactivity control system of the heat pipe reactor, there are methods of rotating the control drum and controlling the upper and lower opening and closing reflectors. For example, the Chinese utility model patent with the publication number CN210182076U discloses a device for remotely driving and controlling the reactivity of a reactor. The control drum of the reactor is composed of neutron-absorbing materials and neutron-reflecting materials. By rotating the angle of the control drum around the core, the relative positions of the neutron-reflecting materials and neutron-absorbing materials with respect to the core are changed, thereby adjusting the reactivity of the reactor. However, multiple control drums arranged around the core will result in a large occupied space, and each columnar control drum needs to be equipped with a motor drive, making the entire mechanism have a large number of components. To solve the problems existing in the above patent, the Chinese invention patent with the publication number CN112037937B discloses a grid-type control drum device for a small fast neutron reactor, which sequentially sleeved around the core from the inside to the outside are an inner reflector, a grid-type control drum, and an outer reflector. The inner reflector is in a cylindrical grid shape and has a fixed position. The grid-type control drum is in a cylindrical grid shape and can rotate a certain angle under the drive of a driving motor to adjust the overlapping area between the absorption grid and the reflection grid of the inner reflector, changing the number of leaked neutrons reflected back to the core, thereby realizing the control of reactivity. This device occupies a small axial space and meets the requirements of miniaturization design; the absorption grid has no axial displacement and will not cause uneven axial power distribution in the core. However, the above solution also has the following disadvantages: setting concentric inner and outer reflectors and a rotatable control drum between the inner and outer reflectors will inevitably result in a large gap between the three, which will cause some neutrons to directly leak, that is, there is a high neutron leakage rate and poor economy. The upper and lower opening and closing reflector control method requires a large height space and is also not conducive to the miniaturization of the device. Summary of the Invention

[0004] The purpose of the present invention is to provide a reactivity control mechanism for a small heat pipe reactor to solve the problems raised in the above background art.

[0005] To achieve the above object, the present invention provides the following technical solution: a reactivity control mechanism for a small heat pipe reactor, comprising two oppositely arranged reflecting side plates. The main body of the reflecting side plate is made of BeO ceramic material and is encapsulated by a radiation-resistant metal cladding. The reflecting side plate is in a 1 / 4 circular ring structure and is used to fit and close the openings on both sides of the heat pipe reactor. It also includes an outer frame and an inner frame that are concentrically installed with the heat pipe reactor and can rotate. The outer frame includes two circular ring plates a arranged up and down. Two symmetric columns a are fixedly connected between the edges of the two circular ring plates a. The circular ring plate a is provided with two centrally symmetric oblong holes. The inner frame is located between the two circular ring plates a. The reflecting side plate is located in the inner frame and is radially slidably connected to the inner frame. Vertically arranged driving columns are respectively provided in the middle of the upper and lower ends of the reflecting side plate. The driving columns penetrate the inner frame and are inserted into the oblong holes. The inner frame and the heat pipe reactor are locked by an electromagnetic lock. When the outer frame rotates, it drives the two reflecting side plates to move synchronously and radially in opposite directions.

[0006] Preferably, it further includes a servo motor. A small gear is fixedly installed on the output shaft of the servo motor. A large gear ring is fixedly installed on one of the circular ring plates a. The small gear meshes with the large gear ring to drive the outer frame to rotate.

[0007] Preferably, swing bearings are respectively connected between the upper and lower ends of the inner frame and the circular ring plates a.

[0008] Preferably, the inner frame includes two circular ring plates b arranged up and down. Two groups of symmetric columns b are fixedly installed between the two circular ring plates b. Two symmetrically arranged radial first guiding holes are provided on the circular ring plates b. The first guiding holes are oblong. The driving columns penetrate the first guiding holes and are slidably connected to them.

[0009] Preferably, second guiding holes parallel to the first guiding holes are respectively arranged on both sides of the first guiding holes. Vertically arranged limiting columns are respectively provided at the upper and lower ends of the reflecting side plate. The limiting columns penetrate the second guiding holes and are slidably connected to them.

[0010] Preferably, rollers are installed at the ends of the limiting columns. The rollers are in contact with the outer side surfaces of the circular ring plates b.

[0011] Preferably, two sector-shaped notches with a radian of π / 2 are symmetrically provided on the circular ring plates b. The sector-shaped notches are used to avoid the columns a.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: The two movable reflecting side plates are opened and closed by means of radial movement plus rotation, thereby controlling the neutron leakage rate and controlling the reactivity. The structure of this mechanism is simple, and it occupies a small space in the radial and axial directions, meeting the design requirements of miniaturization. After the reflecting side plates are closed, they are closely attached to the heat pipe reactor to form a cylinder, and the formed gap is small, which is beneficial to reducing the direct neutron leakage rate and improving the economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a front view structural schematic diagram of the present invention;

[0014] Figure 2 is a three-dimensional structural schematic diagram of the present invention;

[0015] Figure 3 is an exploded structural schematic diagram of the present invention;

[0016] Figure 4 is a three-dimensional structural schematic diagram of the reflection side plate.

[0017] Figure 5 is a schematic diagram of the opening process of the reflection side plate.

[0018] In the figure: 1, reflection side plate; 2, servo motor; 3, pinion gear; 4, outer frame; 41, circular ring plate a; 42, column a; 43, large gear ring; 44, oblong hole; 5, inner frame; 51, circular ring plate b; 52, column b; 53, first guide hole; 54, second guide hole; 55, sector notch; 6, slewing bearing; 7, electromagnetic lock; 8, limit post; 9, roller; 10, driving post. DETAILED DESCRIPTION OF THE INVENTION

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0020] Please refer to Figures 1-5 , the present invention provides a technical solution: a reactivity control mechanism for a small heat pipe reactor, including two relatively arranged reflection side plates 1. The main body of the reflection side plate 1 is made of BeO ceramic material and encapsulated by a radiation-resistant metal cladding. The reflection side plate 1 is a 1 / 4 circular ring structure and is used to adapt to and close the openings on both sides of the heat pipe reactor. Reflection layers are provided on the other two sides of the heat pipe reactor. After the reflection side plates are closed, a complete circular ring-shaped reflection layer is formed. The designed outer diameter of the heat pipe reactor is 138 cm and the height is 150 cm. Beryllium oxide has a relatively high neutron scattering cross-section and can effectively reflect the neutrons leaked from the nuclear reactor back into the reactor to participate in the nuclear reaction to improve the reaction efficiency, which can greatly reduce the critical mass of the nuclear fuel loading. It also includes an outer frame 4 and an inner frame 5 that are concentrically installed with the heat pipe reactor and can rotate. The outer frame 4 includes two circular ring plates a 41 arranged up and down. Two symmetric columns a 42 are fixedly connected between the edges of the two circular ring plates a 41. The circular ring plate a 41 is provided with two oblong holes 44 that are centrosymmetric. A pinion gear 3 is fixedly installed on the output shaft of the servo motor 2. A large gear ring 43 is fixedly installed on one of the circular ring plates a 41. The pinion gear 3 meshes with the large gear ring 43 to drive the outer frame 4 to rotate.

[0021] The inner frame 5 is located between the two circular plates a41, the reflective side panel 1 is located in the inner frame 5 and is radially slidably connected to the inner frame 5, and the upper and lower ends of the reflective side panel 1 are respectively provided with vertical driving columns 10 in the middle. The driving column 10 passes through the inner frame 5 and is inserted into the oblique long hole 44. The inner frame 5 and the heat pipe stack are locked and restricted from rotating by an electromagnetic lock 7 (which is an existing mature technology, widely used on glass doors, and is locked by the principle of magnetic attraction. Two electromagnetic locks 7 are provided and arranged in a centrally symmetrical manner). When the outer frame 4 rotates, it drives the two reflective side panels 1 to move synchronously in opposite radial directions.

[0022] The inner frame 5 has slewing bearings 6 connected to the annular plate a41 at its upper and lower ends. These bearings are used to reduce friction during the relative rotation of the outer and inner frames 4 and 5. The inner frame 5 comprises two annular plates b51, arranged one above the other. Two sets of symmetrical uprights b52 are fixedly mounted between the two annular plates b51. The annular plates b51 are symmetrically provided with two radial first guide holes 53. The first guide holes 53 are elongated, and the drive post 10 extends through the first guide holes 53 and is slidably connected thereto. Parallel second guide holes 54 are provided on either side of the first guide holes 53. Vertical limit posts 8 are provided at the upper and lower ends of the reflective side panel 1. The limit posts 8 extend through the second guide holes 54 and are slidably connected thereto. Rollers 9 are mounted on the ends of the limit posts 8. The rollers 9 contact the outer surfaces of the annular plates b51. When the reflective side panel 1 moves radially, the rollers 9 roll on the surfaces of the annular plates b51, helping to reduce movement resistance. The annular plate b51 is symmetrically provided with two sector-shaped notches 55 with a radian of π / 2, and the sector-shaped notches 55 are used to avoid the pillars a42.

[0023] Working principle: Taking the attached figure as an example, the process of opening the reflective side panel 1 is as follows: the electromagnetic lock 7 locks the inner frame 5 to restrict rotation, the servo motor 2 drives the outer frame 4 to rotate counterclockwise, and the oblique long hole 44 pushes the drive column 10 to move radially outward along the first guide hole 53 to the outermost end. During this process, the reflective side panel 1 moves outward synchronously, and then the electromagnetic lock 7 is powered off to release the rotation lock on the inner frame 5. The outer frame 4 continues to rotate 90 degrees counterclockwise, while driving the inner frame 5 to rotate synchronously, so that the reflective side panel 1 and the side opening of the heat pipe stack are staggered in the circumferential direction, so that the neutrons in the core can leak out.

[0024] When closing the reflective side panel 1, continue to rotate counterclockwise 90 degrees to align the reflective side panel 1 with the opening on the side of the heat pipe stack, then lock the inner frame 5 through the electromagnetic lock 7, and then rotate the outer frame 4 clockwise at a certain angle to make the drive column 10 slide inward along the oblique long hole 44, and the reflective side panel 1 moves radially inward to fit closely with the opening of the heat pipe stack. After closing, the gap of the reflective side panel 1 is extremely small, reducing direct leakage of neutrons.

[0025] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. The reactivity control mechanism of a small-sized heat pipe reactor, comprising two oppositely arranged reflecting side plates (1), the main body of the reflecting side plate (1) being made of BeO ceramic material and encapsulated by a radiation-resistant metal cladding, the reflecting side plate (1) being of a 1 / 4 circular ring structure and adapted to fit and close the two side openings of the heat pipe reactor, characterized in that: It further includes an outer frame (4) and an inner frame (5) that are concentrically installed with the heat pipe stack and rotatable. The outer frame (4) includes two circular ring plates a (41) arranged vertically. Between the edges of the two circular ring plates a (41), two symmetric columns a (42) are fixedly connected. The circular ring plate a (41) is provided with two centrally symmetric oblong holes (44). The inner frame (5) is located between the two circular ring plates a (41). The reflecting side plate (1) is located in the inner frame (5) and is slidably connected to the inner frame (5) radially. The upper and lower ends of the reflecting side plate (1) are respectively provided with vertical driving columns (10) in the middle. The driving columns (10) penetrate through the inner frame (5) and are inserted into the oblong holes (44). The inner frame (5) and the heat pipe stack are locked by an electromagnetic lock (7). When the outer frame (4) rotates, it drives the two reflecting side plates (1) to move synchronously and radially in opposite directions; Between the upper and lower ends of the inner frame (5) and the circular ring plate a (41) respectively, there are slewing bearings (6) connected. The inner frame (5) includes two circular ring plates b (51) arranged vertically. Between the two circular ring plates b (51), two groups of symmetric columns b (52) are fixedly installed. On the circular ring plate b (51), two symmetrically arranged radial first guiding holes (53) are provided. The first guiding holes (53) are strip-shaped. The driving columns (10) penetrate through the first guiding holes (53) and are slidably connected to them. On both sides of the first guiding holes (53), second guiding holes (54) parallel to them are respectively arranged. The upper and lower ends of the reflecting side plate (1) are respectively provided with vertical limiting columns (8). The limiting columns (8) penetrate through the second guiding holes (54) and are slidably connected to them.

2. The reactivity control mechanism of the small heat pipe reactor according to claim 1, characterized in that: It further includes a servo motor (2). A small gear (3) is fixedly installed on the output shaft of the servo motor (2). On one of the circular ring plates a (41), a large gear ring (43) is fixedly installed. The small gear (3) meshes with the large gear ring (43) to drive the outer frame (4) to rotate.

3. The reactivity control mechanism of the small-sized heat pipe reactor according to claim 1, characterized in that: A roller (9) is installed at the end of the limiting column (8). The roller (9) contacts the outer side surface of the circular ring plate b (51).

4. The reactivity control mechanism of the small-sized heat pipe reactor according to claim 3, characterized in that: The circular ring plate b (51) is symmetrically provided with two sector-shaped notches (55) with a radian of π / 2. The sector-shaped notches (55) are used to avoid the columns a (42).

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