Fuel rod test piece suitable for testing edge and angle lattice cells and simulated nuclear reactor

Abstract

The invention provides a fuel rod test piece suitable for testing edge and corner lattice cells and a simulated nuclear reactor. The fuel rod test piece suitable for testing the edge and corner lattice cells is suitable for the simulated nuclear reactor. The fuel rod test piece suitable for testing a corner lattice cell comprises a plurality of simulated fuel rods, and the plurality of simulated fuel rods comprise a first fuel rod with a first temperature and a second fuel rod with a second temperature different from the first temperature, the first fuel rods are located on the periphery of a boundary point of any four simulation fuel assemblies and form an angle lattice cell, and side lattice cells are formed between any two second fuel rods and any two first fuel rods and / or between any four second fuel rods which are symmetrical about a boundary line; and a plurality of intermediate grillages, each intermediate grillage comprises a plurality of small grillages, the small grillages are in one-to-one correspondence with the simulation fuel rods in spatial positions, and the intermediate grillages are suitable for supporting the simulation fuel rods.

Description

Technical Field

[0001] The present application mainly relates to the field of nuclear power testing, and in particular to a fuel rod test piece suitable for testing corner grid elements and a simulated nuclear reactor. Background Art

[0002] The critical heat flux (hereinafter referred to as "CHF") test is a key comprehensive test for studying the thermal performance of fuel assemblies in pressurized water reactor nuclear power plants. The CHF test is usually carried out in a large thermal test bench that simulates the high temperature and high pressure environment of the reactor core. The CHF value obtained through the test, the geometric parameters of the simulated test piece, the local fluid parameters where the CHF occurs, etc. can be further fitted to the CHF relationship to support the core deviation from nucleate boiling ratio (DNBR) analysis.

[0003] Most of the nuclear fuel assembly CHF tests that have been carried out in China use two test pieces: typical grid cells (sub-channels surrounded by four fuel rods in a fuel assembly) and cold wall grid cells (sub-channels surrounded by fuel rods and guide tubes in a fuel assembly). No test has been conducted on the influence of the critical heat flux density of corner grid cells. Since the resistance coefficient of the corner grid cells (sub-channels formed by the fuel rods and gaps between two assemblies) of a fuel assembly is usually higher than that of a typical grid cell and a cold wall grid cell, a large resistance coefficient may lead to a decrease in the flow rate through the grid cell, thereby reducing the CHF value. On the other hand, since there is no guide tube structure in the corner grid cells, the cold wall effect is weakened, and the flow area of ​​the corner grid cells is larger than that of the typical grid cells and the cold wall grid cells, the coolant flow rate through the corner grid cells may also increase, thereby increasing the CHF value. Therefore, the structural characteristics of the corner grid cells and their combined effects on the CHF test results cannot be covered by the CHF test envelope of the typical grid cell and the cold wall grid cell. The corner grid cell test pieces should be used to study the above-mentioned combined effects, which is also one of the focus issues of the current CHF test research of fuel rod bundles. Summary of the invention

[0004] The technical problem to be solved by the present application is to provide a fuel rod test piece suitable for testing edge and corner grid elements and a simulated nuclear reactor, which can obtain the influence of the edge and corner grid element structure of the fuel assembly on the CHF of the fuel assembly, which is conducive to a comprehensive understanding of the thermal performance of the fuel assembly.

[0005] In order to solve the above technical problems, the present application provides a fuel rod test piece suitable for testing corner grid elements, which is suitable for simulating nuclear reactors, wherein the intersection point of any four simulated fuel assemblies in the simulated nuclear reactor is located inside the fuel rod test piece, and any four simulated fuel assemblies include two intersection lines, and the fuel rod test piece includes: a plurality of simulated fuel rods, the plurality of simulated fuel rods include first fuel rods with a first temperature and second fuel rods with a second temperature different from the first temperature, wherein the first fuel rods are located around the intersection points of the any four simulated fuel assemblies and constitute corner grid elements, wherein any two of the second fuel rods symmetrical about the intersection line and any two of the first fuel rods and / or any four of the second fuel rods constitute a corner grid element; a plurality of intermediate grids, each of the intermediate grids includes a plurality of small grids, the small grids correspond one-to-one to the simulated fuel rods in spatial position, and the intermediate grids are suitable for supporting the simulated fuel rods.

[0006] Optionally, each of the small grids includes a strip, a rigid protrusion and a spring, and the strip, the rigid protrusion and the spring are suitable for fixing the small grid and the simulated fuel rod.

[0007] Optionally, the fuel rod test piece further comprises a plurality of sub-channels, and the simulated coolant in the simulated nuclear reactor is suitable for flowing in the sub-channels to dissipate heat for the fuel rod test piece.

[0008] Optionally, each of the small grids further comprises guide wings and mixing wings, wherein the guide wings are suitable for guiding the simulated coolant, and the mixing wings are suitable for accelerating the heat dissipation inside the plurality of simulated fuel rods.

[0009] Optionally, the fuel rod test piece is generally an N×N square-arranged rod bundle, and the fuel rod test piece includes (N+1)×(N+1) sub-channels.

[0010] Optionally, the first fuel rod and the second fuel rod have different radial power distributions.

[0011] Optionally, the fuel rod test piece further comprises a stirring grid, which is arranged around the fuel rod test piece and is suitable for accelerating heat dissipation of the fuel rod test piece.

[0012] Optionally, the fuel rod test piece further comprises a supporting grid, wherein the supporting grid is disposed around the fuel rod test piece and is suitable for supporting the fuel rod test piece.

[0013] In order to solve the above-mentioned technical problems, the present application provides a simulated nuclear reactor, comprising a plurality of simulated fuel assemblies and a fuel rod test piece suitable for testing corner grid elements as described above, wherein the intersection points of any four of the simulated fuel assemblies in the simulated nuclear reactor are located inside the fuel rod test piece, and there are two intersection lines between any four of the simulated fuel assemblies.

[0014] Optionally, the simulated nuclear reactor further comprises a guide tube, which is suitable for guiding control rods in the simulated fuel assembly.

[0015] Compared with the prior art, the present application tests the influence of the edge and corner grid elements on the CHF of the fuel rods through the fuel rod test piece, and simulates the actual situation of the fuel rods in the real nuclear reactor through the intermediate grid, so that the CHF research of the simulated fuel rods can be closer to the real situation. Furthermore, the guide wings and mixing wings of the intermediate grid guide and mix the simulated coolant inside the simulated nuclear reactor to simulate the actual situation of the coolant around the fuel rods in the real nuclear reactor, thereby further improving the reliability and accuracy of the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are included to provide a further understanding of the present application. They are included and constitute a part of the present application. The accompanying drawings illustrate embodiments of the present application and together with the present specification serve to explain the principles of the present application. In the accompanying drawings:

[0017] Figure 1 It is a top view of a fuel rod test piece suitable for testing edge and corner grid elements in one embodiment of the present application;

[0018] Figure 2 It is a structural schematic diagram of an intermediate grid in a fuel rod test piece suitable for testing edge and corner grid elements in one embodiment of the present application;

[0019] Figure 3 It is a cross-sectional view of a fuel rod test piece suitable for testing edge and corner grid elements in one embodiment of the present application;

[0020] Figure 4 It is a structural schematic diagram of a simulated nuclear reactor in one embodiment of the present application. DETAILED DESCRIPTION

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. Unless it is obvious from the language environment or otherwise explained, the same reference numerals in the figures represent the same structure or operation.

[0022] As shown in this application and claims, unless the context clearly indicates an exception, the words "a", "an", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0023] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so that once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0024] In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0025] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0026] In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above words have no special meaning and cannot be understood as limiting the scope of protection of this application. In addition, although the terms used in this application are selected from well-known and commonly used terms, some terms mentioned in the specification of this application may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this article. In addition, it is required to understand this application not only by the actual terms used, but also by the meaning implied by each term.

[0027] This application refers to Figure 1 to Figure 3 A fuel rod test piece 10 suitable for testing corner cells (hereinafter referred to as "fuel rod test piece 10") is shown. The test piece 10 is suitable for Figure 4 The simulated nuclear reactor 20 shown in the figure, any four simulated fuel assemblies 21 (such as Figure 1 The intersection point O of the simulated fuel assembly 22, the simulated fuel assembly 23, the simulated fuel assembly 24 and the simulated fuel assembly 25 shown is located inside the fuel rod test piece 10, and the simulated fuel assembly 22, the simulated fuel assembly 23, the simulated fuel assembly 24 and the simulated fuel assembly 25 include two intersection lines a and b.

[0028] like Figure 1As shown, the fuel rod test piece 10 includes a plurality of simulated fuel rods 11, including a first fuel rod 111 having a first temperature (such as the fuel rods 11 shown as numbers 17, 18, 24 and 25) and a second fuel rod 222 having a second temperature different from the first temperature (the fuel rods 11 of numbers 1 to 16 and numbers 19 to 23). Exemplarily, the simulated fuel rod 11 is an electric heating rod, and different numbers of thermocouples can be set in the electric heating rod to measure the wall temperature of the electric heating rod and monitor the wall temperature soaring phenomenon when the deviation from the nuclear state occurs. Among them, the first temperature is greater than the second temperature. In this embodiment, the first fuel rod 111 is a hot rod, and the second fuel rod 222 is a cold rod. The length of the simulated fuel rod 11 is usually 14 feet, which is similar to the size of the actual fuel rod. The spacing between the plurality of simulated fuel rods 11 can be the same as the spacing of the fuel rods in the actual nuclear reactor, or it can be different. This application does not limit this.

[0029] In this embodiment, the first fuel rods are located around the intersection point O of the simulated fuel assembly 22, the simulated fuel assembly 23, the simulated fuel assembly 24, and the simulated fuel assembly 25 and form corner grid elements 31 and corner grid elements 32 (as shown in the dotted shaded portion), wherein any two second fuel rods symmetrical about the intersection line and any two first fuel rods and / or any four second fuel rods form side grid elements. For example, in this embodiment, the side grid elements include 41, 42, 51, 52, 61, 62, 71, 72, 81, 82, 91, and 92 (as shown in the line shaded portion).

[0030] Furthermore, the fuel rod test piece 10 also includes Figure 2 The intermediate grids 12 shown in the figure each include a plurality of small grids 122, and the small grids 122 correspond to the simulated fuel rods 11 in spatial position. The intermediate grids 12 are suitable for supporting the simulated fuel rods 11, and the fuel rod test piece 10 may include a plurality of intermediate grids 12. For example, in this embodiment, the fuel rod test piece 10 includes 8 intermediate grids 12 (such as Figure 3 shown).

[0031] In this embodiment, the fuel rod test piece 10 is formed by taking 4 simulated fuel rods in the simulated fuel assembly 22 (simulated fuel rods 11 with a specification of 2×2 and numbers 1, 2, 16 and 17), 6 simulated fuel rods in the simulated fuel assembly 23 (simulated fuel rods 11 with a specification of 3×2 and numbers 3, 4, 5, 6, 18 and 19), 6 simulated fuel rods in the simulated fuel assembly 24 (simulated fuel rods 11 with a specification of 2×3 and numbers 12, 13, 14, 15, 23 and 24) and 9 simulated fuel rods in the simulated fuel assembly 25 (simulated fuel rods 11 with a specification of 3×3 and numbers 7, 8, 9, 10, 11, 20, 21, 22 and 25) to form a 5×5 fuel rod test piece 10. Therefore, the specifications of the intermediate grid 12 correspond to the simulated fuel rods 11, which is also a 5×5 grid, including 25 small grids 122 corresponding to the simulated fuel rods 11.

[0032] Furthermore, each small grid 122 includes a strip 123 , a rigid protrusion 124 and a spring 125 , and the strip 123 , the rigid protrusion 124 and the spring 125 are suitable for fixing the small grid 122 and the simulated fuel rod 11 to support each simulated fuel rod 11 in the fuel rod test piece 10 .

[0033] On the other hand, returning to the reference Figure 1 The fuel rod test piece 10 further includes sub-channels T1 to T6, and the simulated coolant in the simulated nuclear reactor is suitable for flowing in the sub-channels to dissipate heat for the fuel rod test piece. Further, each small grid 122 further includes guide wings 126 and mixing wings 127. The guide wings 126 are suitable for guiding the simulated coolant, and the mixing wings 127 are suitable for accelerating the heat dissipation inside the multiple simulated fuel rods 11. By setting the guide wings 126 and the mixing wings 127, the actual application scenario of the fuel rods in the real nuclear reactor can be better simulated, and the accuracy and reliability of the test can be further improved.

[0034] In other embodiments of the present application, a square-arranged rod bundle test piece of N×N specification can be selected according to test requirements. The N×N specification fuel rod test piece includes (N+1)×(N+1) sub-channels, and the present application does not impose any limitation on this.

[0035] In this embodiment, preferably, the first fuel rod 111 and the second fuel rod 222 have different radial power distributions, which means that the first fuel rod 111 and the second fuel rod 222 have different wall thicknesses. Different wall thicknesses can produce different resistances. Therefore, the resistance of the first fuel rod 111 is smaller than the resistance of the second fuel rod 222, thereby making the temperature of the first fuel rod 111 greater than the temperature of the second fuel rod 222. Exemplarily, the radial power ratio of the first fuel rod 111 and the second fuel rod 222 is designed to be 1:0.8. In other embodiments of the present application, the radial power ratio of the first fuel rod 111 and the second fuel rod 222 can be adjusted according to the actual application scenario, and the present application does not limit this.

[0036] Next, refer to Figure 3 The fuel rod test piece 10 further includes a mixing grid 13, which is arranged around the fuel rod test piece 10, wherein the mixing grid 13 is suitable for accelerating the heat dissipation of the fuel rod test piece 10. In order to prevent the bending and deformation of the fuel rods caused by the electromagnetic force of the electric heating between the simulated fuel rods 11, the fuel rod test piece 10 further includes a supporting grid 14, which is arranged around the fuel rod test piece 10. In this embodiment, the supporting grid 14 is located between the plurality of intermediate grids 12, and is suitable for supporting the fuel rod test piece 10. At the same time, it can also minimize the influence of the intermediate grids 12 on the simulated coolant flow field, further improving the accuracy of the simulation test.

[0037] In this embodiment, the fuel rod test piece 10 includes 5 mixing grids 13 and 4 supporting grids 14. The intermediate grids 12, the mixing grids 13 and the supporting grids 14 are staggered and distributed in the axial position of the heating rod at a certain interval. In this embodiment, the mixing grids 13 are concentrated in the upper half of the simulated fuel rods 11, and the supporting grids 14 are concentrated in the lower half of the simulated fuel rods 11. In other embodiments of the present application, different numbers of mixing grids 13 and supporting grids 14 can be set according to actual application scenarios, and the present application does not limit this. Through the setting of the intermediate grids 12, the mixing grids 13 and the supporting grids 14, the fuel rod test piece 10 can be installed more stably, ensuring the structural stability under various test conditions, thereby ensuring the reliability of the test data and the safety of the test.

[0038] Furthermore, after the test begins, the thermocouple in each simulated fuel rod 11 will calculate the CHF value of the corresponding simulated fuel rod 11 to obtain the influence of the side grid element and the corner grid element on the CHF value of the simulated fuel rod 11, so as to infer the influence of the side grid element and the corner grid element on the fuel rod in the real nuclear reactor. In this embodiment, 5 thermocouples are arranged along the axial direction on the inner wall surface of each simulated fuel rod 11 to comprehensively detect the possible occurrence of CHF at various positions of the simulated fuel rod 11, among which the thermocouple in the upstream section of the simulated fuel rod 11 can detect the possibility of CHF occurring at other axial heights.

[0039] On the other hand, the present application also proposes Figure 4 The simulated nuclear reactor 20 shown in FIG. Figure 4 As shown, the simulated nuclear reactor 20 includes a plurality of simulated fuel assemblies and a fuel rod test piece suitable for testing corner cells proposed in any embodiment of the present application, such as the fuel rod test piece 10. Further, the simulated nuclear reactor 20 also includes a guide tube 211, which is suitable for guiding the control rods (not shown) in the simulated fuel assembly.

[0040] This application tests the influence of the edge and corner grid elements on the CHF of the fuel rods through the fuel rod test piece, and simulates the actual situation of the fuel rods in the real nuclear reactor through the intermediate grid, so that the CHF research of the simulated fuel rods can be closer to the real situation. Furthermore, the guide wings and mixing wings of the intermediate grid guide and mix the simulated coolant inside the simulated nuclear reactor to simulate the actual situation of the coolant around the fuel rods in the real nuclear reactor, thereby further improving the reliability and accuracy of the test.

[0041] The basic concepts have been described above. Obviously, for those skilled in the art, the above application disclosure is only an example and does not constitute a limitation of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to the present application. Such modifications, improvements and amendments are suggested in the present application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of the present application.

[0042] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0043] Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thus help understand one or more application embodiments, in the above description of the embodiments of this application, multiple features are sometimes merged into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the object of this application are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0044] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of the present application are approximate values, in specific embodiments, the setting of such numerical values ​​is as accurate as possible within the feasible range.

[0045] Although the present application has been described with reference to the current specific embodiments, ordinary technicians in this technical field should recognize that the above embodiments are only used to illustrate the present application, and various equivalent changes or substitutions may be made without departing from the spirit of the present application. Therefore, as long as the changes and modifications to the above embodiments are within the essential spirit of the present application, they will fall within the scope of the claims of the present application.

Claims

1. A fuel rod test piece suitable for testing edge and corner grid elements, suitable for simulating a nuclear reactor, wherein the intersection points of any four simulated fuel assemblies in the simulated nuclear reactor are located inside the fuel rod test piece, and any four simulated fuel assemblies include two intersection lines, characterized in that: The fuel rod test piece comprises: A plurality of simulated fuel rods, the plurality of simulated fuel rods comprising first fuel rods having a first temperature and second fuel rods having a second temperature different from the first temperature, wherein the first fuel rods are located around the intersection of any four simulated fuel assemblies and constitute a corner grid element, wherein any two of the second fuel rods symmetrical about the intersection line and any two of the first fuel rods and / or any four of the second fuel rods constitute a side grid element; A plurality of intermediate grids, each of the intermediate grids comprises a plurality of small grids, the small grids correspond to the simulated fuel rods in one-to-one spatial position, and the intermediate grids are suitable for supporting the simulated fuel rods.

2. The fuel rod test piece according to claim 1, characterized in that: Each of the small grids includes a strip, a rigid protrusion and a spring, and the strip, the rigid protrusion and the spring are suitable for fixing the small grid and the simulated fuel rod.

3. The fuel rod test piece according to claim 1, characterized in that: The fuel rod test piece also includes a plurality of sub-channels, wherein the simulated coolant in the simulated nuclear reactor is suitable for flowing in the sub-channels to dissipate heat for the fuel rod test piece.

4. The fuel rod test piece according to claim 3, characterized in that: Each of the small grids further comprises a guide wing and a mixing wing, wherein the guide wing is suitable for guiding the simulated coolant, and the mixing wing is suitable for accelerating the heat dissipation inside the plurality of simulated fuel rods.

5. The fuel rod test piece according to claim 3, characterized in that: The fuel rod test piece is usually an N×N square-arranged rod bundle, and the fuel rod test piece includes (N+1)×(N+1) sub-channels.

6. The fuel rod test piece according to claim 1, characterized in that: The first fuel rod and the second fuel rod have different radial power distributions.

7. The fuel rod test piece according to claim 1, characterized in that: Also included is a stirring grid, which is arranged around the fuel rod test piece and is suitable for accelerating the heat dissipation of the fuel rod test piece.

8. The fuel rod test piece according to claim 1, characterized in that: Also included is a support grid, which is disposed around the fuel rod test piece and is suitable for supporting the fuel rod test piece.

9. A simulated nuclear reactor, characterized in that: The invention comprises a plurality of simulated fuel assemblies and a fuel rod test piece suitable for testing corner cells as described in claims 1 to 8, wherein the intersection points of any four of the simulated fuel assemblies in the simulated nuclear reactor are located inside the fuel rod test piece, and any four of the simulated fuel assemblies include two intersection lines.

10. The simulated nuclear reactor according to claim 9, characterized in that: Also included is a guide tube, which is suitable for guiding the control rods in the simulated fuel assembly.

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