CN103985419A - Fuel assembly locking device of liquid-state heavy metal reactor - Google Patents

Abstract

The invention provides a fuel assembly locking device for a liquid heavy metal reactor. The device includes: core fuel assembly (1), core lower grid plate (2), grid plate guide groove (3), fuel assembly pins (4), fixing sleeve (5) and fixing boss (6 ); the core fuel assembly (1) is welded together with the fuel assembly pin (4); the fixing sleeve (5) is axially fixed on the outside of the fuel assembly pin (4) through threads, and can wrap around the fuel assembly pin The central axis of (4) rotates; the fixed boss (6) is welded on the surface of the fixed sleeve (5), the grid plate guide groove (3) is in the hole of the grid plate (2) under the core, and the fixed boss ( 6) Cooperate with the grid plate guide groove (3) to fix the fuel assembly (1) on the core lower grid plate (2). The device in this embodiment has a simple structure and is easy to use, and is located at a place where neutron radiation is relatively weak during use, so it has high safety.

Description

A fuel assembly locking device for a liquid heavy metal reactor

technical field

The invention relates to the technical field of core component design of a heavy metal cooling nuclear reactor, in particular to a fuel assembly locking device of a liquid heavy metal reactor.

Background technique

Liquid lead-bismuth alloy has become the main choice of spallation target and coolant in accelerator driven subcritical system (Accelerator driven system; ADS) system due to its good neutronics performance, excellent radiation resistance performance, heat transfer performance and safety characteristics. The material of choice, while lead-bismuth coolant is also the material of choice for the coolant of advanced fast neutron reactors. Due to the inherent physical properties of the lead-bismuth coolant, its density is much higher than that of the fuel assembly of the liquid metal fast reactor, and the density difference will cause the fuel assembly to generate greater buoyancy, and it is necessary to consider the flow induced by the upward flow of the coolant from the core to the assembly. Vibration issues, so the fuel assembly cannot be held in place by its own weight. Once the fuel assembly moves in the core, it will have a great impact on safety.

At present, most of the fast neutron reactors cooled by liquid metal in the world adopt pool structure. For pool-type research reactors, the primary circuit is completely immersed in the reactor pool, the reactor is in a sealed state, and the upper part is protected by a covering gas (usually argon). Therefore, in order not to damage the sealed state of the reactor and prevent the leakage of radioactive substances, the refueling system of the reactor preferably adopts mechanical remote control operation to refuel, so as to ensure the integrity of the reactor boundary.

Among the current liquid heavy metal reactor fuel assembly design schemes, there are the Russian modular lead-bismuth fast reactor (Svintsovo-Vismutovyi Bystryi Reaktor'-lead-bismuth fast reactor; Russian SVBR) fuel assembly scheme, the EU experimental accelerator-driven subcritical system (The eXperimental Accelerator DrivenSystem; XADS) fuel assembly program and the Advanced Lead Fast Reactor European Demonstrator (ALFRED) fuel assembly program, as well as the Belgian high-tech application multi-purpose hybrid research reactor (Multi-purpose hybrid research reactor for high -tech applications; MYRRHA) fuel assembly program. Among them, the SVBR fuel assembly is fixedly connected in the core and cannot be refueled online. The XADS fuel assembly is equipped with a snap button in the tube pin, and through the guide rod connected with the snap button, the closing and opening of the snap button is controlled to realize the loading and unloading of the fuel assembly. In this scheme, the fuel rod is replaced by a guide rod at the center of the fuel assembly, which reduces the fuel density in the fuel assembly and reduces the economy of the reactor core. Sex is not guaranteed. The ALFRED fuel assembly extends the operating head to directly expose the operating head to the reactor, and fixes the fuel assembly outside the reactor. Since the solution needs to open the top cover for refueling, the radioactive gas inside will enter the space outside the reactor, and other shielding needs to be added outside the reactor to prevent the leakage of highly radioactive gas. The MYRRHA stack fuel assembly places the core grid on the top, presses the fuel assembly through the core grid, and uses buoyancy to fix the fuel assembly. This scheme needs to reserve a large refueling operation space in the lower part of the core, and this area needs to be filled with lead-bismuth alloy, which greatly reduces the economical efficiency of the reactor.

In a word, the above-mentioned existing Russian SVBR fuel assembly scheme, EU XADS fuel assembly scheme and ALFRED fuel assembly scheme, as well as the Belgian MYRRHA fuel assembly scheme have different defects.

Contents of the invention

The invention provides a fuel assembly locking device for a liquid heavy metal reactor, which is used to solve the defects of various fuel assembly solutions in the prior art.

The invention provides a fuel assembly locking device for a liquid heavy metal reactor, the device comprising: core fuel assembly (1), core lower grid plate (2), grid plate guide groove (3), fuel assembly pins ( 4), fixed sleeve (5) and fixed boss (6);

Wherein, the core fuel assembly (1) is welded together with the fuel assembly pin (4); the fixing sleeve (5) is axially fixed on the outside of the fuel assembly pin (4) through threads , and can rotate around the central axis of the fuel assembly pin (4); the fixed boss (6) is welded on the surface of the fixed sleeve (5), and the grid guide groove (3) is located In the hole of the grid plate (2) under the core, the fixing boss (6) cooperates with the guide groove (3) of the grid plate to fix the fuel assembly (1) under the core on the grille (2).

Optionally, in the above device, wherein, the core fuel assembly (1) is a hexagonal cylinder.

Optionally, in the above-mentioned device, wherein, the fuel assembly pin (4) is cylindrical.

Optionally, in the above-mentioned device, wherein, the grid guide groove (3) is an inner zigzag groove.

Optionally, in the above-mentioned device, wherein, the number of the fixing bosses (6) is the same as the number of the inner zigzag grooves of the grid guide groove (3).

Optionally, in the above-mentioned device, the number of the fixing bosses (6) and the number of inner zigzag grooves of the grid guide groove (3) are both three.

Optionally, in the above-mentioned device, wherein, the fuel assembly pin (4) includes an upper part (41) of the fuel assembly pin (4) and a lower part ( 42) Two parts, the fixing sleeve (5) is inserted into the upper part (41) of the fuel assembly pin (4), and the lower part (42) of the fuel assembly pin (4) is threaded It is connected with the upper part (41) of the fuel assembly pin (4), and axially fixes the fixing sleeve (5) on the fuel assembly pin (4).

Optionally, in the above-mentioned device, wherein, the line contact between the fuel assembly pin (4) and the fixing sleeve (5) is a cone or an arc.

The present invention also provides a method for fuel assembly refueling using the fuel assembly locking device of any one of the above liquid heavy metal reactors, comprising the following steps:

When charging, the refueling mechanism controls the core fuel assembly (1) to insert the fuel assembly pins (4) into the installation holes in the lower grid plate (2) of the core to fix the The sleeve (5) slides into the grid guide groove (3) together with the fixing boss (6), so that the fixing boss (6) rotates along the lower plane of the grid guide groove (3) until the bottom;

The refueling mechanism pulls the core fuel assembly (1) to lift up, so that the fixed boss (6) rotates to the top along the upper plane of the grid guide groove (3), and at this position passes the ball and surface contact fixation;

When refueling, the refueling mechanism presses down the core fuel assembly (1) again, and the fixed boss (6) rotates along the lower plane of the grid guide groove (3) until it reaches the bottom, then the refueling The mechanism is lifted upwards, and the core fuel assembly (1) is detached from the lower core grid (2) to realize refueling.

The fuel assembly locking device of the liquid heavy metal reactor of the present invention not only provides sufficient axial restraint for the fuel assembly through the cooperation of the grid plate and the fuel assembly, but also does not affect the upward removal of the fuel assembly for refueling. The fuel assembly locking device of the liquid heavy metal reactor of the present invention has a simple structure, is very convenient to use, can be used many times, and can effectively reduce the cost of refueling. And when used, it is located at a position where neutron irradiation is relatively weak, and has high safety; it can also effectively prevent the movement of fuel elements in the liquid heavy metal pile, and can realize online refueling of the reactor. In addition, this locking device can better overcome the thermal stress caused by thermal axial deformation of the components.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is a schematic cross-sectional view of a fuel assembly locking device of a liquid heavy metal reactor provided by an embodiment of the present invention.

Fig. 2 is a partial axial sectional view of the fuel assembly locking device of the liquid heavy metal reactor provided by the embodiment of the present invention.

Fig. 3 is a partial longitudinal sectional view of the fuel assembly locking device of the liquid heavy metal reactor provided by the embodiment of the present invention.

Fig. 4 is a partial axial expansion view of the fuel assembly locking device of the liquid heavy metal reactor provided by the embodiment of the present invention.

Fig. 5 is a flowchart of a method for refueling a fuel assembly using the fuel assembly locking device of the liquid heavy metal reactor in the above embodiment provided by an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Fig. 1 is a schematic cross-sectional view of a fuel assembly locking device of a liquid heavy metal reactor provided by an embodiment of the present invention. As shown in Figure 1, the fuel assembly locking device of the liquid heavy metal reactor in this embodiment includes: core fuel assembly 1, core lower grid plate 2, grid plate guide groove 3, fuel assembly pin 4, fixed sleeve 5 And fixed boss 6.

Wherein, the core fuel assembly 1 is welded together with the fuel assembly pin 4; the fixing sleeve 5 is axially fixed on the outer side of the fuel assembly pin 4 through threads, and can rotate around the central axis of the fuel assembly pin 4; The platform 6 is welded on the surface of the fixing sleeve 5, the grid guide groove 3 is located in the hole of the grid plate 2 under the core, and the fixing boss 6 cooperates with the grid guide groove 3 to fix the fuel assembly 1 under the core grid 2.

As shown in Figure 1, from the relative positions of the core fuel assembly 1, the lower core grid 2, the grid guide groove 3, the fuel assembly pin 4, the fixing sleeve 5 and the fixing boss 6, it can be known that the fuel assembly 1 The lower part is inserted into the lower grid plate 2 of the core, and the axial positioning of the fuel assembly in the core is completed through the cooperation of the boss 6 axially fixed on the assembly pin 4 and the guide groove 3 of the grid plate. During the refueling process, the refueling machine grabs the head of the fuel assembly 1, and the fixing and unlocking of the fuel assembly 4 in the core can be completed through a simple up and down movement.

For example, the core fuel assembly 1 in this embodiment can be a hexagonal cylinder; the core fuel assembly 1 in the reactor in this embodiment adopts a hexagonal cylinder; this is related to the arrangement of cells in the reactor. The hexagonal components can be spliced together to form the reactor core like a honeycomb. The pin 4 of the fuel assembly is cylindrical; in theory, the pin 4 of the fuel assembly can also adopt other shapes, but because the circular shape has good alignment performance and the convenience of processing, the design of the fast neutron reactor uses a cylindrical The effect of the shaped fuel assembly pin 4 is better, but it does not exclude the use of other shapes, such as the shape of a square cylinder. The grid guide groove 3 is an inner zigzag groove.

Optionally, the number of fixing bosses 6 in this embodiment is the same as the number of inner zigzag grooves of grid guide groove 3 .

The fuel assembly locking device of the liquid heavy metal reactor in this embodiment, through the cooperation of the grid plate and the fuel assembly, not only provides sufficient axial restraint for the fuel assembly, but also does not affect the upward removal of the fuel assembly for refueling. The fuel assembly locking device of the liquid heavy metal reactor in this embodiment has a simple structure, is very convenient to use, can be used many times, and can effectively reduce the cost of refueling. And when used, it is located at a position where neutron irradiation is relatively weak, and has high safety; it can also effectively prevent the movement of fuel elements in the liquid heavy metal pile, and can realize online refueling of the reactor. In addition, this locking device can better overcome the thermal stress caused by thermal axial deformation of the components.

Fig. 2 is a partial axial sectional view of the fuel assembly locking device of the liquid heavy metal reactor provided by the embodiment of the present invention. As shown in Figure 2, it can be seen from the axial section view that the fuel assembly pin 4 includes two parts, the upper part 41 of the fuel assembly pin 4 and the lower part 42 of the fuel assembly pin 4, and the fixing sleeve 5 is inserted into the fuel assembly pin 4 The upper part 41 of the fuel assembly pin 4 is connected with the upper part 41 of the fuel assembly pin 4 through threads, and the fixing sleeve 5 is axially fixed on the fuel assembly pin 4 . For example, the line contact between the pin 4 of the fuel assembly and the fixed sleeve 5 is a cone and an arc, which can effectively reduce the influence of self-welding between the two contact surfaces due to metal diffusion.

Fig. 3 is a partial longitudinal sectional view of the fuel assembly locking device of the liquid heavy metal reactor provided by the embodiment of the present invention. As shown in FIG. 3 , in this embodiment, the number of fixed bosses 6 and the number of inner zigzag grooves of grid plate guide groove 3 are both three to illustrate the technical solution. As shown in FIG. 3 , it can be seen from the longitudinal sectional view that the grid guide groove 3 is located in the installation hole of the grid plate 2 under the core, and the fixing sleeve 5 is installed concentrically with the fuel assembly pin 4 . There are three fixing bosses 6 for each fuel assembly 1 , which are located on the fixing sleeve 5 . The fixing boss 6 is inserted into the position corresponding to the grid guide groove 3 .

Fig. 4 is a partial axial expansion view of the fuel assembly locking device of the liquid heavy metal reactor provided by the embodiment of the present invention. As shown in FIG. 4 , the grid plate guide groove 3 expands in the axial direction, and the fixing boss 6 moves along the serrated edge in the grid plate guide groove 3 . When charging, the refueling mechanism inserts the fuel assembly pin 4 into the installation hole in the lower grid plate 2 of the core, and the fixed sleeve 5 drives the fixed boss 6 to slide into the grid plate guide groove 3, which is located at the position ① in the figure ; The fixed boss 6 rotates along the lower plane of the grid guide groove 3 and goes down to the bottom, which is located at the position ② in the figure; The top is located at the position ③ in the figure, and is fixed at this position by the contact between the ball and the surface. When refueling, the refueling mechanism presses down the core fuel assembly 1 again, and the fixed boss 6 rotates along the lower plane of the grid guide groove 3 to the bottom, which is the position ④ in the figure, and the refueling mechanism lifts up , the fixed boss 6 moves to the position ⑤ in the figure, and the core fuel assembly 1 is detached from the core lower grid plate 2 to realize the process of refueling.

The working principle of the fuel assembly locking device of the liquid heavy metal reactor in the above embodiment: insert the fuel assembly pin 4 into the mounting hole in the lower grid plate 2 of the core, and slide the fixing sleeve 5 together with the fixing boss 6 into the guide groove of the grid plate 3, and make the fixed boss 6 rotate along the lower plane of the grid guide groove 3 to the bottom; when the core fuel assembly 1 is lifted up, the fixed boss 6 at the bottom follows the movement of the core fuel assembly 1, so that the fixed boss 6 Rotate along the upper plane of the grid guide groove 3 to the top, and fix at this position through the contact between the ball and the surface. This contact is beneficial to prevent the self-welding effect between the structural steels when they are still in the core for a long time; When refueling, the core fuel assembly 1 is pressed down again, and the fixed boss 6 is rotated along the lower plane of the grid guide groove 3 to the bottom, and the refueling mechanism is lifted upwards, and the core fuel assembly 1 is separated from the lower grid 2. Realize refueling.

The fuel assembly locking device of the liquid heavy metal reactor in the above embodiment, through the cooperation of the grid plate and the fuel assembly, not only provides sufficient axial restraint for the fuel assembly, but also does not affect the upward removal of the fuel assembly for refueling. The fuel assembly locking device of the liquid heavy metal reactor in this embodiment has a simple structure, is very convenient to use, can be used many times, and can effectively reduce the cost of refueling. And when used, it is located at a position where neutron irradiation is relatively weak, and has high safety; it can also effectively prevent the movement of fuel elements in the liquid heavy metal pile, and can realize online refueling of the reactor. In addition, this locking device can better overcome the thermal stress caused by thermal axial deformation of the components.

Fig. 5 is a flowchart of a method for refueling a fuel assembly using the fuel assembly locking device of the liquid heavy metal reactor in the above embodiment provided by an embodiment of the present invention. Wherein, the details of the fuel assembly locking device of the liquid heavy metal reactor can be found in the descriptions of the above-mentioned embodiments, and will not be repeated here. During use, the refueling mechanism is connected to the head of the core fuel assembly 1, and the refueling mechanism controls the fuel assembly locking device of the liquid heavy metal reactor by controlling the core fuel assembly 1 to realize refueling. The method for fuel assembly refueling using the fuel assembly locking device of the liquid heavy metal reactor of the above embodiment in this embodiment may specifically include the following steps:

100. When charging, the refueling mechanism controls the core fuel assembly 1 to insert the fuel assembly pin 4 into the installation hole in the lower grid plate 2 of the core, and slide the fixing sleeve 5 together with the fixing boss 6 into the grid plate The guide groove 3 makes the fixed boss 6 rotate along the lower plane of the grid plate guide groove 3 to the bottom;

When the fixed boss 6 rotates along the lower plane of the grid guide groove 3 to the bottom, when the core fuel assembly 1 moves upward, it is easier to cooperate with the upper guide groove. 101. The refueling mechanism pulls the core fuel assembly 1 upwards, so that the fixed boss 6 rotates along the upper plane of the grid guide groove 3 to the top, and fixes it at this position through the contact between the ball and the surface;

The refueling mechanism pulls the core fuel assembly 1 to lift upward, and the fixed boss 6 at the bottom follows the movement of the core fuel assembly 1, so that the fixed boss 6 can rotate to the top along the upper plane of the grid guide groove 3, and here The position is fixed by the contact between the ball and the surface. This kind of contact is beneficial to prevent the self-welding effect between the structural steels when standing still in the core for a long time.

102. When refueling, the refueling mechanism presses down the core fuel assembly 1 again, and the fixed boss 6 rotates along the lower plane of the grid guide groove 3 to the bottom, then the refueling mechanism lifts up, and the core fuel assembly 1 is separated from the lower grid plate 2 of the core to realize refueling.

By adopting the refueling method of this embodiment, it is very convenient, and the fuel assembly locking device of the liquid heavy metal reactor can be used many times, which can effectively reduce the cost of refueling. Moreover, the fuel assembly locking device of the liquid heavy metal reactor is located at a position where the neutron irradiation is relatively weak, so the safety is high; it can also effectively prevent the fuel elements from moving in the liquid heavy metal reactor, and can realize online refueling of the reactor.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (9)

1. the fuel assembly locking device of a liquid heavy metal reactor, it is characterized in that, described device comprises: reactor fuel assembly (1), reactor core lower grid plate (2), screen guide groove (3), fuel assembly pin (4), fixed muffle (5) and fixing lug boss (6);

Wherein, described reactor fuel assembly (1) is welded as a whole with described fuel assembly pin (4); Described fixed muffle (5) is axially fixed in the outside of described fuel assembly pin (4) by screw thread, and can rotate around the central shaft of described fuel assembly pin (4); Described fixing lug boss (6) is welded on the surface of described fixed muffle (5), described screen guide groove (3) is for being positioned at the hole of described reactor core lower grid plate (2), described fixing lug boss (6) coordinates with described screen guide groove (3), and described fuel assembly (1) is fixed on described reactor core lower grid plate (2).

2. device according to claim 1, is characterized in that, described reactor fuel assembly (1) is hexagon cylinder.

3. device according to claim 1, is characterized in that, described fuel assembly pin (4) is column type.

4. device according to claim 1, is characterized in that, described screen guide groove (3) is interior zigzag slot.

5. device according to claim 4, is characterized in that, the number of described fixing lug boss (6) is identical with the number of the interior zigzag slot of described screen guide groove (3).

6. device according to claim 5, is characterized in that, the number of the interior zigzag slot of the number of described fixing lug boss (6) and described screen guide groove (3) is three.

7. device according to claim 1, it is characterized in that, described fuel assembly pin (4) comprises the top (41) of described fuel assembly pin (4) and bottom (42) two parts of described fuel assembly pin (4), described fixed muffle (5) is inserted in the described top (41) of described fuel assembly pin (4), the described bottom (42) of described fuel assembly pin (4) is connected with the described top (41) of described fuel assembly pin (4) by screw thread, and described fixed muffle (5) is axially fixed on described fuel assembly pin (4).

8. device according to claim 7, is characterized in that, between described fuel assembly pin (4) and described fixed muffle (5), for circular cone, contacts with the line of circular arc.

9. use the as above fuel assembly locking device of the arbitrary described liquid heavy metal reactor of claim 1-9 to carry out the method that fuel assembly reloads, it is characterized in that, comprise the steps:

When carrying out when filling with substance, refueling agency inserts the mounting hole in described reactor core lower grid plate (2) by controlling described reactor fuel assembly (1) by described fuel assembly pin (4), described fixed muffle (5) is slipped into described screen guide groove (3) together with described fixing lug boss (6), make described fixing lug boss (6) along the rotation of described screen guide groove (3) lower plane until bottommost;

Refueling agency pulls described reactor fuel assembly (1) upwards to promote, and makes described fixing lug boss (6) along the upper Plane Rotation of described screen guide groove (3) to top, and fixes with contacting of face by ball in this position;

When reloading, refueling agency presses down described reactor fuel assembly (1) again, described fixing lug boss (6) is along the rotation of screen guide groove (3) lower plane until after bottommost, refueling agency upwards promotes, described reactor fuel assembly (1) departs from described reactor core lower grid plate (2), and realization is reloaded.