WO2016119292A1

WO2016119292A1 - Flow distribution device and nuclear reactor assembly with same

Info

Publication number: WO2016119292A1
Application number: PCT/CN2015/075081
Authority: WO
Inventors: 杨江; 卢向晖; 王婷; 崔军; 庄程军; 林维青; 林建树; 林支康; 方思远; 沙正峰; 陶俊; 赵常有; 蒋晓华
Original assignee: 中广核研究院有限公司; 中国广核集团有限公司; 中国广核电力股份有限公司
Priority date: 2015-01-28
Filing date: 2015-03-26
Publication date: 2016-08-04
Also published as: GB2536990A; GB2536990B; CN104637553A; JP2017511889A; JP6452732B2; GB201521617D0

Abstract

Provided is a flow distribution device, which comprises a flow distribution member (50) in a concave structure, wherein the concave structure forms a flow distribution cavity (53) having an opening, the flow distribution member (50) is arranged inside a pressure container (10) in a hung fashion and located right below a nuclear reactor core (30), the opening of the flow distribution member (50) faces towards the nuclear reactor core (30), a central hole (54) is further formed in the centre of the bottom of the flow distribution member (50) in a penetrating fashion, the central hole (54) is located right below the nuclear reactor core (30), and a plurality of flow splitting holes (55) are further formed in the flow distribution member (50) in a penetrating fashion; and under the actions of the central hole (54) and the flow splitting holes (55), a coolant can uniformly and stably flow into the nuclear reactor core (30), and the coolant is effectively prevented from generating a vortex under the action of the central hole (54) so that the uniformity and stability of the coolant flow distribution are further improved; moreover, since no vortex is generated, the safety and reliability of the nuclear reactor are guaranteed and the occurrence of nuclear safety accidents is reduced. Also disclosed is a nuclear reactor assembly with the flow distribution device.

Description

Flow distribution device and nuclear reactor assembly having the same

Technical field

The present invention relates to a nuclear reactor apparatus, and more particularly to a flow distribution device and a nuclear reactor assembly that optimize the distribution of coolant in a pressure vessel.

Background technique

With the maturity of nuclear energy utilization technology, the safety of nuclear power plants has also been continuously improved, and the construction of nuclear power plants has gradually become an important energy guarantee for national development.

A certain number of fuel rods are arranged at regular intervals (eg, 15×15 or 17×17, etc.) and are fixed into a bundle called a reactor fuel assembly. The reactor fuel assembly is mainly composed of a pipe seat, upper and lower pipe sockets, a positioning grid, and a guide. The tube and the fuel rod are composed. Typical reactor fuel assemblies are used in nuclear reactors for 3-5 years. Because they are in a strong neutron field, they are subjected to high temperature, high pressure, high flow rate coolant flushing, and are subject to fission product chemistry and complex mechanical loads. Therefore, the working conditions are very demanding.

It is well known that the chain reaction in a nuclear reactor generates a large amount of radioactive substances harmful to the human body, such as iodine 131, cesium 137, etc. In order to avoid leakage of these radioactive materials, a multi-layered protective layer is disposed outside the nuclear reactor: the first layer, the zirconium alloy casing, In order to avoid the contact of the radioactive material in the fuel rod with the coolant, a zirconium alloy casing is wrapped around the fuel rod, the zirconium alloy casing can withstand a high temperature of 1200 ° C; the second layer, the reactor pressure vessel, the reactor pressure vessel is used for In the nuclear reactor core, the nuclear reactor core will generate huge steam pressure. Therefore, the reactor pressure vessel is made of high-strength alloy steel. The protection function is to ensure that the radioactive material will not be large when the zirconium alloy casing of the fuel rod is damaged. The third layer, the concrete safety shell, is placed outside the reactor pressure vessel. Its main function is to prevent a large amount of radioactive materials and radioactive waste from leaking to the outside after the reactor pressure vessel is exploded or damaged. It is worth mentioning that The reactor of the Chernobyl nuclear power plant in the former Soviet Union did not have this safety. The outer casing, thus causing the reactor to explode easily after the explosion of the reactor, resulting in a large amount of radioactive dust directly entering the atmosphere, causing long-term serious nuclear pollution of the surrounding environment, resulting in serious consequences of no man's land.

Therefore, the fuel rod undergoes a controlled chain reaction in the core of the nuclear reactor, generating a large amount of heat, which directly promotes the turbine generator through the conversion of the coolant, thereby realizing the utilization of nuclear energy, namely: coolant It is to transfer the energy released by nuclear fission to a boiler or turbine outside the reactor and convert kinetic energy into a carrier of electrical energy. The coolant may be a liquid or a gas, which is circulated between the nuclear reactor and the boiler by a transfer pump; sometimes the coolant may also serve as a moderator.

It can be seen from the above that the main purpose of providing multi-layer protection for nuclear reactors is to ensure that radioactive materials in nuclear reactors do not leak to the outside world after accidents such as explosions in nuclear reactors, and the decisive factor for ensuring that nuclear reactors do not explode is to control nuclear reactors. The in-core chain reaction speed and temperature, so the flow distribution and control of the coolant in the pressure vessel is important, which directly affects the power generation efficiency and the safety of the entire nuclear reactor. For example, the initial design of the Westinghouse AP1000 did not provide a flow distribution skirt within the pressure vessel, and CFD calculations performed in this case indicated that the core reactor inlet flow distribution was unacceptable. Therefore, Westinghouse has added a flow distribution skirt 50' (see Fig. 1) in the pressure vessel. The flow distribution skirt 50' has an annular structure and is provided with a plurality of small diameter holes 51' of equal diameters, and the CFD calculation is repeated. The following table shows the core flow distribution for the presence or absence of the flow distribution skirt 50':

As can be seen from the above comparison table, after the flow distribution skirt 50' is added, the flow distribution is more uniform, and the power generation efficiency and the safety of the nuclear reaction can be further improved.

As shown in Fig. 2, the flow distribution skirt 50' of this structure is installed in the pressure vessel 10'. During operation, when the coolant flows rapidly in the lower head 11', due to the design of the flow distribution skirt 50' itself The defect and the support member 32' block the coolant, so that the coolant will have a strong vortex in the lower head, causing the internal components to fall off, resulting in a safety accident, so the flow distribution of the structure The skirt is in need of improvement.

Based on the above reasons, the applicant has developed a flow distribution device with high stability and reliability through long-term research and production practice. The flow distribution device has uniform structural design and uniform flow distribution compared with the existing flow distribution skirt. Sexuality and anti-whirlpool have broken through the existing concept, and made up for the shortcomings of the existing flow distribution skirt through small structural changes, and achieved positive results.

Summary of the invention

It is an object of the present invention to provide a flow distribution device that is uniform, reliable, and stable in flow distribution and that is effective in preventing vortex generation.

Another object of the present invention is to provide a nuclear reactor assembly having a flow distribution device that distributes the flow rate of the coolant uniformly, reliably, stably, and effectively prevents vortex generation.

In order to achieve the above object, the present invention provides a flow distribution device suitable for flow distribution of a coolant in a pressure vessel, wherein the flow distribution device includes a flow distribution member having a recessed structure, the recessed structure being formed An open flow distribution chamber, the flow distribution member being suspended in the pressure vessel and located directly below the core of the nuclear reactor, the opening of the flow distribution member facing the nuclear reactor core, the flow distribution member A central hole is also formed in the center of the bottom portion, and the central hole is located directly below the core of the nuclear reactor, and a plurality of distribution holes are further formed in the flow distribution member.

Preferably, the upper edge of the flow distribution member projects outwardly to form a flange that is coupled to the core lower support plate of the nuclear reactor core.

Preferably, the flow distribution device further includes a support member, a lower end of the support member is fixed to the lower seal of the pressure vessel, and the flow distribution member is fixed to the upper end of the support member.

Preferably, the flow dividing holes are evenly distributed around the central hole.

Preferably, the flow dividing holes on the flow distribution member gradually become smaller from the bottom to the top.

Preferably, the flow distribution member has a hemispherical shape of a hollow structure, and the hollow structure forms the flow distribution chamber.

Preferably, the flow distribution member has a semi-ellipsoidal shape of a hollow structure, and the hollow structure forms the flow distribution chamber.

Preferably, the diverting hole and the central hole are opened on the flow distribution member in a vertical direction.

Preferably, the axial line of the flow dividing hole and the central hole is perpendicular to the wall surface of the flow distribution member.

The nuclear reactor assembly provided by the present invention comprises a pressure vessel, wherein the pressure vessel is provided with a hanging basket, the nuclear basket is provided with a nuclear reactor core, and the pressure vessel is connected with a cold heat pipe, wherein the pressure vessel is further included as described above. a flow distribution device, wherein the flow distribution member of the flow distribution device is suspended directly below the nuclear reactor core disposed in the pressure vessel.

Compared with the prior art, since the flow distribution member of the flow distribution device of the present invention has a concave structure, and the flow distribution member is suspended directly below the nuclear reactor core disposed in the pressure vessel, the opening of the flow distribution member is oriented The nuclear reactor core, the center of the bottom of the flow distribution member is further provided with a central hole, the central hole is located directly below the core of the nuclear reactor, and the flow distribution member is further provided with a plurality of diversion holes, and the coolant is in the central hole and the diversion hole. Uniform and stable flow into the core of the nuclear reactor under the action, and the coolant effectively prevents the generation of vortices under the action of the central hole, further improves the uniformity and stability of the coolant flow distribution, and at the same time makes the nuclear reactor due to the absence of vortex generation. Safety and reliability are guaranteed, reducing the occurrence of nuclear safety accidents.

DRAWINGS

1 is a schematic structural view of a conventional flow distribution skirt.

2 is a schematic view showing the structure of a nuclear reactor assembly in which the flow distribution skirt shown in FIG. 1 is mounted.

Figure 3 is a schematic view showing the structure of a first embodiment of the nuclear reactor assembly of the present invention.

Figure 4 is a schematic view showing the structure of a second embodiment of the nuclear reactor assembly of the present invention.

Figure 5 is a schematic view showing the structure of the flow distribution member of the flow distribution device of the present invention in a hemispherical shape.

FIG. 5a is a schematic view of another perspective structure of FIG. 5. FIG.

Figure 5b is a schematic side view of Figure 5.

Figure 5c is a schematic bottom view of Figure 5.

Fig. 6 is a schematic view showing the structure of the flow distribution member of the flow distribution device of the present invention having a semi-ellipsoidal shape.

FIG. 6a is a schematic view of another perspective structure of FIG. 6. FIG.

Figure 6b is a schematic side view of Figure 6.

Figure 6c is a schematic bottom view of Figure 6.

detailed description

Embodiments of the present invention will now be described with reference to the drawings, in which like reference numerals represent like elements.

As shown in FIG. 3 and FIG. 4, the nuclear reactor assembly 100 of the present invention includes a pressure vessel 10 in which a gondola 20 is disposed, and a nuclear reactor core 30 is disposed in the gondola 20, and the pressure vessel 10 is connected The cold heat pipe 40, the nuclear reactor assembly 100 further includes a flow distribution device having a flow distribution member 50 that is suspended in the pressure vessel 10 and located in the nuclear reactor core 30. Directly below; since the nuclear reactor assembly 100 of the present invention has a flow distribution device, the coolant in the pressure vessel 10 can flow into the nuclear reactor core 30 uniformly and stably. Specifically, the flow distribution member 50 of the flow distribution device of the present invention is disposed in the pressure vessel 10 by being suspended in the following two ways, as follows:

In the first manner, as shown in FIG. 3, the upper edge of the flow distribution member 50 of the present invention protrudes outwardly to form a flange 51 which is welded to the core lower support plate 31 of the nuclear reactor core 30. Or the threaded connection is connected such that the flow distribution member 50 of the present invention is suspended in the pressure vessel 10, and the core lower support plate 31 of the nuclear reactor core 30 is pressed against the opening 52 of the flow distribution member 50. Further, the coolant flowing through the flow distribution member 50 of the present invention can directly enter the nuclear reactor core 30; the structure is simple and the design is reasonable.

In a second manner, as shown in FIG. 4, the flow distribution device further includes a support member 32. The lower end 321 of the support member 32 is fixed to the lower head 11 of the pressure vessel 10, and the flow distribution member 50 The upper end 322 of the support member 32 is fixed, so that the flow distribution member 50 is suspended in the pressure vessel under the action of the support member 32, and the core lower support plate 31 of the nuclear reactor core 30 is pressed against the flow rate. The coolant 52 of the fitting 50, and thus the coolant flowing through the flow distribution member 50 of the present invention, can directly enter the nuclear reactor core 30; the structure is simple and easy to install and maintain.

The two embodiments disclosed above for the flow distribution member 50 to be suspended in the pressure vessel 10 are only preferred embodiments of the present invention, and of course, the flow distribution member 50 may not be limited to the right range. Those skilled in the art can propose other solutions without any creative labor under the premise of the technical solution provided by the present invention, such as by other supporting methods and welding methods. The flow distribution member 50 is disposed in the pressure vessel 10 in a floating manner and, therefore, will not be described in detail herein.

The flow distribution device of the nuclear reactor assembly 100 of the present invention will be further described in detail below with reference to Figures 5 - 6c:

5 to 6c, the flow distribution device of the present invention includes a flow distribution member 50 having a recessed configuration, the recessed structure forming a flow distribution chamber 53 having an opening 52 through which the flow distribution member 50 passes. The opening 52 of the flow distribution member 50 is disposed in a manner of being welded to the lower core support plate 31 or suspended in a manner of being supported by the support member 32 in the pressure vessel 10 and directly below the nuclear reactor core 30. In the nuclear reactor core 30, a central hole 54 is defined in the center of the bottom of the flow distribution member 50. The central hole is located directly below the nuclear reactor core 30, and the flow distribution member 50 is further provided with a plurality of openings. Splitter 55.

Continuing with the combination of FIGS. 5-6c, preferably, the flow dividing holes 55 are uniformly distributed around the central hole 54; the evenly distributed splitting holes 55 further improve the uniformity of the coolant flow distribution, thereby ensuring The stability and safety of the work.

Continuing with the combination of FIG. 5 and FIG. 6c, preferably, the diverting holes 55 on the flow distribution member 50 are gradually reduced from bottom to top; that is, the diverting holes 55 at each level are the same size and different levels. The flow dividing holes 55 form a plurality of rows of holes in the vertical direction, and the split holes 55 in the upper row are smaller in diameter than the split holes 55 in the lower row.

Continuing with the combination of Figures 5 - 5c, preferably, the flow distribution member 50 is a hemispherical hollow structure, the hollow structure forming the flow distribution chamber 53; the flow distribution member 50 in this embodiment The flange protrudes outward to form a flange 51 which is connected to the core lower support plate 31 of the nuclear reactor core 30 by welding, so that the flow distribution member 50 of the present invention is suspended and placed under pressure In the container, the core lower support plate 31 of the nuclear reactor core 30 is pressed against the opening 52 of the flow distribution member 50, so that the coolant flowing through the flow distribution member 50 of the present invention can directly enter the nuclear reactor core 30.

Continuing with the combination of Figures 6-6c, preferably, the flow distribution member 50 has a semi-ellipsoidal shape of a hollow structure that forms the flow distribution chamber 53.

Continuing with the combination of FIG. 5 and FIG. 6c, preferably, the diverting hole 55 and the central hole 54 are vertically opened on the flow distribution member 50; that is, the axes of the diverting hole 55 and the central hole 54 are vertical. direction.

Continuing with the combination of FIG. 5 and FIG. 6c, preferably, the shaft hole 55 and the center hole 54 are axially suspended. Straight to the wall surface of the flow distribution member 50; that is, the opening direction of the branch hole 55 and the center hole 54 is perpendicular to the wall surface of the flow distribution member 50.

As can be seen from the above, the diameter of the center hole 54 of the flow distribution member 50 of the present invention is larger than that of the branch hole 55, and the annular cavity formed between the inner wall surface of the lower head 11 and the outer wall surface of the flow distribution member 50 when the coolant is formed. Flowing downwardly and through the splitter 55 while flowing uniformly into the flow distribution chamber 53 at the same time, when part of the remaining coolant flows to the height of the center hole 54, the portion of the coolant enters the flow distribution chamber through the center hole 54. 53; since there is only one central hole 54 and the aperture is large and farthest from the inlet of the nuclear reactor core 30, the coolant passing through the central hole 54 does not affect the inlet flow distribution unevenness of the nuclear reactor core 30; The large central hole 54 can reduce the local resistance coefficient of the flow distribution member 50 and other components in the lower seal 11 without increasing the excessive load on the primary circuit of the first circuit that supplies power to the coolant, optimizing the nuclear reaction system. The water flow characteristics of the first loop system; in addition, when a nuclear reactor has a large water loss accident, the flow distribution member 50 can reduce the reverse flow of the nuclear reactor core 30 in the discharge stage, and the large break water loss During the discharge stage, due to the vaporization of the nuclear reactor core 30, the nuclear reactor core 30 undergoes a reverse flow, and a large amount of the nuclear reactor core 30 fluid flows from the nuclear reactor core 30 through the lower header 11 to the descending section, thereby causing the heat transfer of the nuclear reactor core 30 to deteriorate, and the flow distribution member 50 increases the flow resistance of the coolant from the inlet to the descending section of the nuclear reactor core 30, that is, the flow distribution member 50 forms a retaining action in the event of a large breakage water loss accident, reducing the countercurrent head and the countercurrent flow, thereby controlling and Relieve the escalation of the accident.

3 to 6c, since the flow distribution member 50 of the flow distribution device of the present invention has a recessed structure, and the flow distribution member is suspended directly below the nuclear reactor core 30 in the pressure vessel 10, the flow rate is The opening 52 of the sub-assembly 50 faces the nuclear reactor core 30, and a central hole 54 is also formed through the center of the bottom of the flow distribution member 50. The central hole 54 is located directly below the nuclear reactor core 30, and the flow distribution member 50 is also opened. There are a plurality of split holes 55, and the coolant flows into the nuclear reactor core 30 uniformly and stably under the action of the center hole 54 and the split hole 55, and the coolant effectively prevents the generation of vortices under the action of the center hole 54, further improving The uniformity and stability of the coolant flow distribution, and the safety and reliability of the nuclear reactor are guaranteed due to the absence of vortex generation, thereby reducing the occurrence of nuclear safety accidents; therefore, the flow distribution device of the present invention and the existing flow distribution Compared with skirts, it breaks through the existing concepts in structural design, flow distribution uniformity and anti-vortexing, and makes up for it through smaller structural changes. Some defects skirt flow distribution exists, and has made a positive benefit.

In addition, the specific structure and working principle of the pressure vessel 10, the hanging basket 20 and the nuclear reactor core 30 according to the present invention are well known to those skilled in the art and will not be described in detail herein.

The above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, and the equivalent changes made by the scope of the present invention remain within the scope of the present invention.

Claims

A flow distribution device adapted to distribute a flow rate of a coolant in a pressure vessel, wherein the flow distribution device comprises a flow distribution member having a recessed structure, the recessed structure forming a flow distribution chamber having an opening, The flow distribution member is suspended in the pressure vessel and located directly under the nuclear reactor core, the opening of the flow distribution member faces the nuclear reactor core, and the center of the bottom portion of the flow distribution member is further opened. There is a central hole, which is located directly below the core of the nuclear reactor, and a plurality of flow holes are further formed in the flow distribution member.
The flow distribution device of claim 1 wherein the upper edge of the flow distribution member projects outwardly to form a flange that is coupled to the core lower support plate of the nuclear reactor core.
A flow distribution device according to claim 1, further comprising a support member, a lower end of said support member being fixed to a lower head of said pressure vessel, said flow distribution member being fixed to said support member Upper end.
The flow distribution device according to claim 1, wherein said flow dividing holes are uniformly distributed around said center hole.
The flow distribution device according to claim 4, wherein the flow dividing hole on the flow distribution member gradually becomes smaller from the bottom to the top.
A flow distribution device according to claim 4, wherein said flow distribution member has a hemispherical shape of a hollow structure, said hollow structure forming said flow distribution chamber.
A flow distribution device according to claim 4, wherein said flow distribution member has a semi-ellipsoidal shape of a hollow structure, said hollow structure forming said flow distribution chamber.
The flow distribution device according to claim 4, wherein the flow dividing hole and the central hole are opened in the vertical direction on the flow distribution member.
A flow distribution device according to claim 4, wherein said flow dividing hole and central opening The axis of the axis is perpendicular to the wall of the flow distribution member.
A nuclear reactor assembly includes a pressure vessel, a pressure basket is disposed therein, a nuclear reactor core is disposed in the basket, and the pressure vessel is connected with a cold heat pipe, and is characterized in that: In the flow distribution device according to any one of the preceding claims, the flow distribution member of the flow distribution device is suspended directly below the nuclear reactor core in the pressure vessel.