CHF test voltage measuring rod and test device

Abstract

The invention discloses a voltage measuring rod for a CHF test and a test device, and belongs to the field of nuclear power. The voltage measuring rod for the CHF test comprises conductive assemblies, a heating tube and a voltage measuring assembly, the conductive assemblies are arranged at the two ends of the heating tube and connected with an external power supply, and the conductive assemblies are conductively connected with the heating tube to form a heating circuit; the voltage measuring assembly comprises a first voltage measuring line and a second voltage measuring line which are arranged at the two ends of the heating pipe. The first voltage measuring line and the second voltage measuring line are connected with the voltage measuring circuit so that the voltage measuring circuit can measure the voltage at the two ends of the heating pipe. The voltage measuring rod for the CHF test can accurately measure the effective energy input of the electric heating rod in the CHF test, and the precision of the CHF test is improved.

Description

Technical Field

[0001] The invention belongs to the field of nuclear power, and in particular relates to a voltage measuring rod and a test device for a CHF test. Background Art

[0002] The critical heat flux (CHF) test is a key test for the study of the thermal performance of nuclear power plant fuel assemblies using salt water. It is used to simulate the phenomenon of temperature jump on the surface of the heating rod caused by heat transfer deterioration when the critical heat flux occurs under high temperature and high pressure conditions in the reactor core, so as to determine the heating power when CHF occurs, and then derive the CHF value of the fuel assembly under this condition, and then fit the CHF relationship to support the core deviation from nucleate boiling ratio (DNBR) analysis. When conducting a CHF test, it is necessary to accurately measure the voltage of the electric heating device to obtain the energy input of the electric heating device. However, there is power loss between the DC power supply and the rod bundle heating section, and directly calculating the rod bundle heating power with the power supply input voltage will produce errors. Therefore, providing a device that can accurately reflect the voltage of the electric heating rod in the CHF test is of positive significance for improving the accuracy of the CHF test. Summary of the invention

[0003] The purpose of the present invention is to provide a voltage measuring rod for CHF test, which can accurately measure the voltage of the heating section of the CHF test electric heating device. The present invention also provides a CHF test device.

[0004] According to an embodiment of one aspect of the present invention, there is provided a voltage measuring rod for a CHF test, the voltage measuring rod comprising:

[0005] Conductive components, heating tubes and pressure measuring components;

[0006] Wherein, the conductive components are arranged at both ends of the axial direction of the heating tube and connected to an external power source, and the conductive components and the heating tube are conductively connected to form a heating circuit;

[0007] The pressure measuring assembly includes a first pressure measuring line, a second pressure measuring line and a pressure measuring circuit, wherein the first pressure measuring line and the second pressure measuring line are respectively connected to two ends of the heating tube and are connected to the pressure measuring circuit to allow the pressure measuring circuit to measure the voltage between the two ends of the heating tube;

[0008] The voltage measuring rod for CHF test is used for CHF test of pressurized water reactor.

[0009] The voltage measuring rod for CHF test can directly measure the voltage of the effective heating section in the CHF test, avoiding the test error caused by the heat generated by the conductive component being included in the system energy input and the calculation error of the indirect calculation method, thereby improving the test accuracy.

[0010] Furthermore, in some embodiments, the heating tube is made of Inconel 600 alloy.

[0011] Inconel 600 alloy has good heat generation performance and good corrosion resistance in high temperature water environment.

[0012] Furthermore, in some embodiments, the wall thickness of the heating tube is configured to be uniform or to be distributed in a gradient manner along the axial direction.

[0013] Heating tubes of equal thickness can simulate the working condition of uniform axial power distribution; heating tubes with gradient distribution along the axial direction can simulate non-uniform axial power. According to different test conditions, the use of different types of heating tubes can improve the accuracy of CHF test simulation.

[0014] Furthermore, in some embodiments, the conductive component includes a first conductive component and a second conductive component, the heating tube is arranged vertically, the first conductive component is arranged at the upper end of the heating tube, and the second conductive component is arranged at the lower end of the heating tube.

[0015] Furthermore, in some embodiments, the first conductive component is configured as a nickel rod, and the second conductive component is configured as a terminated nickel tube and a nickel-plated copper rod, wherein the nickel tube is connected to the heating tube.

[0016] Furthermore, in some embodiments, the purity of the nickel coating of the nickel rod, the nickel tube and the nickel-plated copper rod is not less than 99.9%.

[0017] Furthermore, in some embodiments, the support body is disposed inside the heating tube and provides radial support to the heating tube.

[0018] The support body can maintain the structural stability of the heating tube under high temperature and high pressure test conditions, and prevent the heating tube from being crushed by the cooling medium under long-term high temperature test conditions.

[0019] Furthermore, in some embodiments, the support body is configured as a ceramic support body.

[0020] The ceramic support has high hardness, rigidity and insulation performance, and can improve the reliability of the voltage measuring rod.

[0021] Furthermore, in some embodiments, the conductive component and the heating tube are connected by silver brazing.

[0022] Silver brazing connections reduce electrical resistance at the soldered connection location, reducing losses.

[0023] According to an embodiment of another aspect of the present invention, a CHF test device is provided, which includes a grid and a test rod, wherein the grid provides mounting positions, the mounting positions are arranged in a 5×5 mounting position matrix, and the test rod is installed on the mounting position; the test rod includes a central long rod, a hot rod, a cold rod and a voltage measuring rod, one central long rod is installed in the center of the mounting position matrix, eight hot rods are circumferentially arranged around the central long rod, fifteen cold rods and one voltage measuring rod are circumferentially arranged around the hot rod, wherein the voltage measuring rod is arranged at the mounting position at a vertex of the mounting position matrix; the voltage measuring rod adopts the voltage measuring rod for CHF testing provided in any of the aforementioned embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the structure of a voltage measuring rod for a CHF test in an embodiment;

[0025] Figure 2 This is a schematic diagram of the structure of a first conductive component in an embodiment;

[0026] Figure 3 This is a schematic diagram of the structure of a medium-thickness heating tube in an embodiment;

[0027] Figure 4 This is a schematic diagram of the structure of a ceramic support body adapted to a heating tube of equal thickness in one embodiment;

[0028] Figure 5 This is a schematic diagram of the structure of a variable thickness heating tube in another embodiment;

[0029] Figure 6 It is a schematic diagram of the structure of a ceramic support body adapted to a variable thickness heating tube in another embodiment;

[0030] Figure 7 This is a schematic diagram of the structure of a nickel tube in one embodiment;

[0031] Figure 8 This is a schematic diagram of the structure of a nickel-plated copper rod in one embodiment;

[0032] Fig. 9 This is a schematic diagram of the arrangement position of the pressure measuring line in one embodiment;

[0033] Fig.10 Schematic diagram of the structure of a CHF test device in one embodiment.

[0034] The meaning of the reference numerals: 1-heating tube; 2-ceramic support body; 3-first conductive component; 4-nickel tube; 5-nickel-plated copper rod; 6-silver brazing; 7-first pressure measuring line; 8-second pressure measuring line; 9-fastening nut; 10-lead-out ceramic component; 11-lead hole; 12-wiring groove; 13-reducing section; 14-screw hole; 15-grid.

[0035] The purpose of the above drawings is to explain the present invention in detail so that those skilled in the art can understand the technical concept of the present invention, but it is not intended to limit the present invention. For the sake of simplicity, the above drawings only schematically illustrate the structures related to the technical features of the present invention, and do not strictly draw the complete device and all details according to the actual proportion. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0037] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The phrase appearing in various locations in the specification does not necessarily refer to the same embodiment, nor is it limited to mutually exclusive independent or alternative embodiments. Those skilled in the art should be able to understand that the embodiments herein may be combined with other embodiments without causing structural conflicts.

[0038] In the description of this article, unless otherwise clearly specified and limited, the technical terms "installed", "connected", "connected" and the like should be understood in a broad sense, such as a movable connection, a fixed connection or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of this application can be understood according to specific circumstances.

[0039] In the description of this document, terms indicating orientation or positional relationships, such as "up", "down", "left", "right", "horizontal", "vertical", "height", "length", and "width", are intended to accurately describe the embodiments and simplify the description, but are not intended to limit the parts or structures involved to have a specific orientation, be installed or operate in a specific orientation, and should not be construed as a limitation on the embodiments in this document.

[0040] In the description of this article, the terms "first", "second" and the like are only used to distinguish different objects, and cannot be understood as indicating relative importance or limiting the quantity, specific order or primary and secondary relationship of the described technical features. In the description of this article, the meaning of "plurality" is at least two.

[0041] In order to eliminate the possible errors between the indirect measurement method and the estimation based on the simulation test and improve the accuracy of the CHF simulation test, an embodiment of one aspect of the present invention provides a voltage measuring rod for CHF test, which can directly measure the voltage of the effective heating section in the CHF test device, thereby improving the measurement accuracy of the actual energy input during the CHF test and more accurately obtaining the thermal parameters when the CHF phenomenon occurs.

[0042] The structure of the device is as follows Figure 1As shown, it includes a heating tube 1, a ceramic support body 2, a first conductive component 3 made of a nickel rod, and a second conductive component composed of a nickel tube 4 and a nickel-plated copper rod 5. Among them, the first conductive component 3 and the second conductive component are respectively arranged at the axial ends of the heating tube 1 to form an axial limit for the heating tube 1. The first conductive component 3, the heating tube 1 and the second conductive component are axially connected to form a conductive connection to form a heating circuit of the test device, which is used to simulate the heat generation of the fuel rod during the CHF test. During the test, the heat generated by the heating tube 1 is considered to be an effective heat input to the system, and the heat generated by the first conductive component 3, the nickel tube 4 and the nickel-plated copper rod 5 is not included in the heat input of the system. Therefore, in order to accurately calculate the energy input of the system during the CHF test, it is necessary to exclude the heat generation effect of the first conductive component 3, the nickel tube 4 and the nickel-plated copper rod 5 during the calculation process. Therefore, a pressure measuring component is also provided in the test device, and the pressure measuring component includes a first pressure measuring line 7 and a second pressure measuring line 8, such as Fig. 9 As shown, the first pressure measuring line 7 and the second pressure measuring line 8 are respectively connected to the two ends of the heating tube 1 and are connected to the pressure measuring circuit (not shown), thereby allowing the pressure measuring circuit to directly measure the voltage between the two ends of the heating tube 1, and then determine the heat input to the system provided by the heating tube 1.

[0043] In a preferred embodiment, the heating tube 1 is made of Inconel 600 alloy. Inconel 600 alloy has good heating efficiency, good strength and water corrosion resistance under high temperature conditions, and is an ideal heating material in the CHF test.

[0044] The heating tube 1 and the first conductive component 3 are connected by silver brazing 6 to ensure good conductivity between the heating tube 1 and the first conductive component 3 and reduce interface resistance loss. The heating tube 1 and the nickel tube 4 are also connected by silver brazing (not shown), and the nickel tube 4 and the heating tube 1 can have good welding compatibility. The nickel tube 4 and the nickel-plated copper rod 5 can also be connected by silver brazing, wherein the base of the nickel-plated copper rod 5 is made of pure copper, and copper has a lower resistance than nickel, which can further reduce the resistance loss at one end of the second conductive component.

[0045] Specifically, the structure of the first conductive component 3 is as follows: Figure 2 As shown, one end of the first conductive component 3 is provided with a wiring slot 12 for connecting to an external DC power supply; the other end is provided with a reducing section 13 for connecting to the heating tube 1 and providing a welding contact surface for the silver brazing 6.

[0046] In a preferred embodiment, the first conductive component 3 is made of nickel having a purity of not less than 99.9%.

[0047] Figure 3Schematic diagram of the structure of the heating tube 1 in one embodiment, in which the heating tube 1 is a cylindrical structure of equal thickness made of Inconel 600 alloy. When an external DC power supply is connected, heat can be generated uniformly in the axial direction, thereby simulating the heating state of the fuel assembly with axial uniform power.

[0048] In a preferred embodiment, the combination Figure 1 , a ceramic support 2 is also provided in the heating tube 1. Under the CHF test condition, the heating tube 1 is immersed in a high-temperature and high-pressure cooling medium. During the long-term test, under the influence of high temperature and high-pressure loads, the thin-walled heating tube 1 is at risk of being crushed by the high-pressure cooling medium. Providing a ceramic support 2 in the heating tube 1 to provide radial support for the heating tube 1 can avoid the risk of failure of the heating tube 1 and improve the reliability of the test device.

[0049] In a preferred embodiment, the ceramic support 2 has a structure as follows: Figure 4 As shown, the configuration is as follows Figure 3 The heating tube shown has a matching cylindrical structure, and the outer wall of the ceramic support body 2 matches the inner wall of the heating tube 1, providing radial support from the inside to the outside for the heating tube 1. The ceramic support body 2 is entirely inserted into the heating tube 1, and one end thereof is connected to a lead-out ceramic component 10, which is partially inserted into the heating tube 1 and partially inserted into the nickel tube 4. The lead-out ceramic component 10 is provided with a lead-in hole 11, and when a thermocouple needs to be set in the voltage measuring rod, the thermocouple wire can be led out through the lead-in hole 11.

[0050] In another embodiment, Figure 5 As shown, the heating tube 1 is made of an Inconel 600 alloy tube with variable thickness, and the thickness of the tube wall is distributed in a gradient in the axial direction. When an external DC power supply is connected, the heating tube 1 can generate heat non-uniformly in the axial direction, thereby simulating the heating state of a fuel assembly with axial non-uniform power.

[0051] Correspondingly, such as Figure 6 The ceramic support 2 shown can be used with Figure 5 In this embodiment, the outer surface of the ceramic support 2 is an inclined conical surface and matches the variable thickness heating tube 1 shown. Figure 5 The inner walls of the heating tube 1 shown cooperate with each other, thereby providing radial support for the heating tube 1 from the inside to the outside.

[0052] The structure of the nickel tube 4 is as follows Figure 7 As shown, one end of the nickel tube 4 is welded to the heating tube 1 by silver brazing, and the other end is welded to the nickel-plated copper rod 5 by silver brazing to achieve current conduction. The nickel tube 4 has good welding compatibility with the Inconel 600 heating tube 1, and has good welding strength and reliability.

[0053] The structure of the nickel-plated copper rod 5 is as follows: Figure 8 As shown, one end of the nickel-plated copper rod 5 can be nested and welded with the nickel tube 4, and the other end is provided with a screw hole 14 for installing a fastening nut 9 to fix the voltage measuring rod.

[0054] In a preferred embodiment, the nickel purity of the nickel coating on the nickel tube 4 and the nickel-plated copper rod 5 is not less than 99.9%, and the copper matrix purity of the nickel-plated copper rod 5 is not less than 99.9%. Pure copper has a lower resistivity and can effectively reduce the resistance loss at one end of the second conductive component.

[0055] In other embodiments, the heating tube 1 may also be replaced by other high temperature resistant and corrosion resistant metal materials, such as Inconel 718 alloy or zirconium alloy.

[0056] In some embodiments, when a thermocouple is not required in the heating tube 1 , the lead hole 11 may be omitted.

[0057] In other embodiments, according to the different power distribution characteristics of the fuel rods to be simulated in the test design, the wall thickness of the heating tube 1 may also adopt other distribution forms.

[0058] According to another embodiment of the present invention, a CHF test device is provided. Fig.10 As shown, the device includes a grid 15, and the grid 15 is composed of a plurality of crossed nickel alloy strips. The crossed nickel alloy strips in the grid 15 provide installation positions for the test rods. Specifically, the test rods include a central long rod, a hot rod, a cold rod and a voltage measuring rod. In the embodiment, the nickel alloy strips are crossed to form a 5×5 rectangular installation position matrix. Among them, one central long rod A is set at the center of the 5×5 installation position matrix, and 8 hot rods B are arranged around the central long rod A. The outermost side of the installation position matrix is ​​15 cold rods C and a voltage measuring rod D, and the voltage measuring rod D is set at a vertex position of the installation position matrix. The voltage measuring rod D adopts the voltage measuring rod for CHF test provided in any of the aforementioned embodiments.

[0059] The purpose of the above embodiments is to further explain the present invention in detail in conjunction with the accompanying drawings so that those skilled in the art can understand the technical concept of the present invention. Within the scope of the present invention, the optimization or equivalent replacement of the part structure involved, and the optimization of the implementation methods in different embodiments without conflicting structures and principles, all fall within the protection scope of the present invention.

Claims

1. A voltage measuring rod for CHF test, characterized in that: include: Conductive components, heating tubes and pressure measuring components; Wherein, the conductive components are arranged at both ends of the axial direction of the heating tube and connected to an external power source, and the conductive components and the heating tube are conductively connected to form a heating circuit; The pressure measuring assembly includes a first pressure measuring line, a second pressure measuring line and a pressure measuring circuit, wherein the first pressure measuring line and the second pressure measuring line are respectively connected to two ends of the heating tube and are connected to the pressure measuring circuit to allow the pressure measuring circuit to measure the voltage between the two ends of the heating tube; The voltage measuring rod for CHF test is used for CHF test of pressurized water reactor.

2. The voltage measuring rod for CHF test according to claim 1, characterized in that: The heating tube is made of Inconel600 alloy.

3. The voltage measuring rod for CHF test according to claim 1, characterized in that: The wall thickness of the heating tube is uniform or distributed in a gradient along the axial direction.

4. The voltage measuring rod for CHF test according to claim 1, 2 or 3, characterized in that: The conductive component includes a first conductive component and a second conductive component. The heating tube is arranged vertically. The first conductive component is arranged at the upper end of the heating tube, and the second conductive component is arranged at the lower end of the heating tube.

5. The voltage measuring rod for CHF test according to claim 4, characterized in that: The first conductive component is configured as a nickel rod, and the second conductive component is configured as a terminated nickel tube and a nickel-plated copper rod, wherein the nickel tube is connected to the heating tube.

6. The voltage measuring rod for CHF test according to claim 5, characterized in that: The purity of the nickel coating of the nickel rod, the nickel tube and the nickel-plated copper rod is not less than 99.9%.

7. The voltage measuring rod for CHF test according to claim 1, 2 or 3, characterized in that: It also includes a support body, which is arranged in the heating tube and provides radial support for the heating tube.

8. The voltage measuring rod for CHF test according to claim 7, characterized in that: The support body is configured as a ceramic support body.

9. The voltage measuring rod for CHF test according to claim 1, 2 or 3, characterized in that: The conductive component and the heating tube are connected by silver brazing.

10. A CHF test device, comprising a grid and a test rod, characterized in that: The grid provides mounting positions, and the mounting positions are arranged in a 5×5 mounting position matrix, and the test rod is installed on the mounting position; the test rod includes a central long rod, a hot rod, a cold rod and a voltage measuring rod, one central long rod is installed in the center of the mounting position matrix, eight hot rods are circumferentially arranged around the central long rod, fifteen cold rods and one voltage measuring rod are circumferentially arranged around the hot rod, wherein the voltage measuring rod is arranged at the mounting position at a vertex of the mounting position matrix; the voltage measuring rod adopts the voltage measuring rod for CHF test as described in any one of claims 1 to 9.

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