A method for measuring the lifting force of a pressurized water reactor fuel assembly

Abstract

The application discloses a kind of pressurized water reactor fuel assembly lifting force measurement methods, it is related to pressurized water reactor measurement technical field, comprising the following steps: a plurality of force sensors are arranged between fuel assembly lower nozzle base and reactor core lower plate contact surface;In the test body, without water and upper nozzle plate spring is in free state, in the test body, without water and upper nozzle plate spring is in the state of compression, in the test body, fill up water and flow rate is zero, in the test body, fill up water and specified test flow, respectively measured pressure load resultant force;Respectively calculated to obtain upper nozzle plate spring compression force, underwater buoyancy and lifting force under the action of water power.The scheme is adopted, the hydraulic test is carried out to the simulation fuel assembly of equal proportion (1:1), equal density to obtain prototype fuel assembly lifting force;Borrow the method of the patent can accurately measure the lifting force of pressurized water reactor fuel assembly dry weight, underwater buoyancy and water power, provide basis for the design of fuel assembly upper nozzle plate spring.

Description

Technical Field

[0001] The present invention relates to the technical field of pressurized water reactor measurement, and in particular to a method for measuring the lifting force of a pressurized water reactor fuel assembly. Background Art

[0002] When coolant flows through the core of a pressurized water reactor (PWR), it exerts strong forces on the fuel assemblies, causing axial and circumferential deformation and stress on the fuel assemblies, which may affect the safety and economic efficiency of the reactor. In engineering, the lifting force of a fuel assembly is defined as the net upward force acting on the fuel assembly due to the flow of coolant, which does not include the weight and buoyancy of the fuel assembly. Under normal operating conditions, the fuel assembly is not allowed to move due to the flow of coolant. To prevent the fuel assembly from floating up within the reactor's operating flow range, a compression spring structure is designed on the fuel assembly upper tube seat to provide a compression force to secure the fuel assembly.

[0003] If the compression force of the upper tube seat compression spring structure is too high, it can easily damage the fuel assembly; if it is too low, the fuel assembly will float. Therefore, fuel assembly lifting force calculations are essential in reactor thermal-hydraulic design to determine whether the fuel assembly compression spring design meets relevant standards. Traditionally, theoretical analysis and program calculations have been used in China to estimate fuel assembly lifting force. No literature has been found that uses experimental measurement methods to determine fuel assembly lifting force. Consequently, fuel assembly lifting force calculations lack real-world test data verification. Summary of the Invention

[0004] The present invention aims to solve the problem in the prior art of the lack of real test data verification in the calculation of the lifting force of fuel assemblies. It aims to provide a method for measuring the lifting force of pressurized water reactor fuel assemblies. By adopting this scheme, the lifting force of the prototype fuel assembly is obtained by conducting hydraulic tests on simulated fuel assemblies of equal proportion (1:1) and equal density. By using this patented method, the dry weight, underwater buoyancy and lifting force under hydraulic action of the pressurized water reactor fuel assembly can be accurately measured, providing a basis for the design of the fuel assembly upper tube seat plate spring.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for measuring the lifting force of a pressurized water reactor fuel assembly comprises the following steps:

[0007] A plurality of force sensors are arranged between the lower tube seat of the fuel assembly and the contact surface of the lower plate of the core, wherein the plurality of force sensors are distributed at the bottom of the lower tube seat of the fuel assembly;

[0008] Then, when there is no water in the test body and the upper tube seat plate spring is in a free state, the pressure load resultant force ∑F is measured. airf ;

[0009] When there is no water in the test body and the upper tube seat plate spring is in a compressed state, the pressure load resultant force ∑F is measured. airp ;

[0010] When the test body is filled with water, the flow rate is zero and the upper tube seat spring is in a compressed state, the pressure load resultant force ∑F is measured. sw ;

[0011] Fill the test body with water, specify the test flow rate and put the upper tube seat spring in the compressed state, and measure the pressure load resultant force ∑F fw ;

[0012] According to ∑F airf ,∑F airp ,∑F sw and ∑F fw , the spring compression force of the upper tube seat plate, the underwater buoyancy and the lifting force under the action of water force are calculated respectively.

[0013] Compared with the existing technology, China has always used theoretical analysis and program calculation methods to estimate the lifting force of fuel assemblies, and no relevant literature reports have been found on the use of experimental measurement methods to obtain the lifting force of fuel assemblies, resulting in the problem that the fuel assembly lifting force calculation lacks real experimental data verification. The present invention provides a method for measuring the lifting force of pressurized water reactor fuel assemblies. By adopting this scheme, the lifting force of the prototype fuel assembly is obtained by conducting hydraulic tests on simulated fuel assemblies; using this patented method, the dry weight, underwater buoyancy and lifting force under hydraulic action of the pressurized water reactor fuel assembly can be accurately measured, providing a basis for the design of the fuel assembly upper tube seat plate spring.

[0014] In the specific scheme, several force sensors are first installed between the contact surface of the fuel assembly lower tube seat and the lower core plate. Several of the force sensors are distributed at the bottom of the fuel assembly lower tube seat. In this way, the multiple force sensors can be used to measure under various working conditions. Among them, when weighing the fuel assembly, the steady-state force sensor of this scheme is compared with the measurement data of a calibrated electronic crane scale, and the error is less than 3.5%. After installation, the test body is free of water and the fuel assembly upper tube seat plate spring is in a free state. The pressure load resultant force ∑F is measured. airf (Unit: N); When there is no water in the test body and the spring of the upper tube seat of the fuel assembly is in a compressed state, the pressure load resultant force ∑F is measured airp (Unit: N); When the test body is filled with water, the flow rate is zero, and the spring of the upper tube seat of the fuel assembly is in a compressed state, the pressure load resultant force ∑F is measured sw (Unit: N); The test body is filled with water, the test flow rate is specified, and the spring of the upper tube seat of the fuel assembly is in a compressed state. The pressure load resultant force ∑F is measured. fw(Unit: N); the dry weight of the fuel assembly G (kN) is the pressure load resultant force measured when there is no water in the test body and the fuel assembly upper tube seat plate spring is in a free state, that is, G = ∑F airf ; In the above pressure load resultant force ∑F airf , i.e. the dry weight of the fuel assembly G, the resultant pressure load ∑F airp , pressure load resultant force ∑F sw and pressure load ∑F fw Finally, the upper tube seat spring compression force, underwater buoyancy and hydraulic lifting force are calculated and deduced. The upper tube seat spring compression force can be obtained from the pressure load resultant force ∑F airp The difference between the dry weight G of the fuel assembly and the underwater buoyancy can be obtained by the pressure load force ∑F airp and pressure load ∑F sw The difference between them is obtained, and the lifting force under hydraulic action can be obtained by the pressure load force ∑F sw and pressure load ∑F fw The difference between the two values ​​is calculated. By determining the upper tube seat spring compression force, underwater buoyancy, and hydraulic lifting force, it is possible to determine whether the preload force of the newly designed fuel assembly upper tube seat spring meets the requirements. If not, the fuel assembly upper tube seat spring structure design can be optimized and adjusted. Furthermore, a customized steady-state force sensor with matching specifications and dimensions and waterproofing can be developed based on the total weight of the pressurized water reactor fuel assembly and the lower tube seat structure to be measured.

[0015] The above scheme aims to achieve the following: This scheme can be applied to the off-pillar hydraulic load testing of pressurized water reactor fuel assemblies. This test obtains the lifting force of the prototype fuel assembly by conducting hydraulic tests on simulated fuel assemblies. The method described in this patent can accurately measure the dry weight of the fuel assembly, its underwater buoyancy, the lifting force under hydraulic pressure, and the preload force of the fuel assembly's upper tube seat spring, providing a basis for the design of the fuel assembly's upper tube seat spring.

[0016] In a further solution, the upper tube seat spring compression force F k The calculation formula is:

[0017] F k =∑F airp -∑F airf .

[0018] In a further embodiment, the underwater buoyancy F g The calculation formula is:

[0019] F g =∑F airp -∑F sw .

[0020] In a further embodiment, the lifting force F under the hydraulic actioni The calculation formula is:

[0021] F i =∑F sw -∑F fw .

[0022] In a further embodiment, four force sensors are provided, each located at the four legs of the fuel assembly lower tube seat. By placing the force sensors at the legs of the lower tube seat, the pressure transmitted from the fuel assembly can be measured in real time, thereby improving measurement accuracy.

[0023] In a further solution, the force sensor is a waterproof steady-state force sensor.

[0024] In a further solution, a plurality of countersunk holes are evenly distributed on the lower plate of the core, and the force sensor is installed at the position of the countersunk hole with its probe extending out of the countersunk hole; four water flow holes are also evenly distributed in the middle of the lower plate of the core.

[0025] A further solution is that, in order to facilitate the separate lead-out of the leads, a number of lugs extend from the circumferential ends of the core lower plate, each of which has a lead-through hole opened inside. One end of the lead-through hole is connected to the end of the lug, and the other end of the lead-through hole is connected to a corresponding countersunk hole. In this solution, the simulated core lower plate is specially prepared, and a lug with a lead-through hole extends from each of the four sides of the simulated core lower plate to lead out the signal line of the force sensor. The lead-through hole diameter does not exceed 7mm. The four countersunk holes for placing steady-state force sensors (11mm high, 20mm outer diameter) are 9mm deep and have a hole diameter of Φ20.4mm. After the signal lines of the four steady-state force sensors are led out from the lead-through hole, they are wrapped with a double-layer flange gasket on the DN100 interface pipe on the test cylinder and led out to the junction box outside the test cylinder. The output load resultant force signal is incorporated into the data acquisition.

[0026] A further approach involves designing a stainless steel backing plate thick enough to withstand the weight of the fuel assembly without visible deformation, to improve the accuracy of test data measurements. This backing plate is positioned directly above the probes of several force sensors and connected to the probes of these force sensors or to the four legs of the fuel assembly lower tube holder. The thickness of the backing plate is ≥ 2mm. In this approach, the backing plate is flush with the simulated core lower plate and can be installed on the four legs of the fuel assembly lower tube holder or on the probes of the four force sensors. This ensures that the four force sensors are evenly stressed during pressure load measurements, improving measurement accuracy.

[0027] A further embodiment further includes a signal processing module and a display module connected to the force sensors. The signal processing module is configured to receive and process the force sensor signals, and the display module is configured to display the processing results of the signal processing module. In this embodiment, a steady-state force parallel scale can be used. The steady-state force parallel scale includes four specially designed waterproof steady-state force sensors, a 24V DC power supply, a signal processing module, and a display module. The four specially designed waterproof steady-state force sensors transmit the detected signals to the signal processing module, which calculates the results using the corresponding formula model to obtain the detection results, and ultimately displays the detection results on the display module.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] 1. The present invention provides a method for measuring the lifting force of a pressurized water reactor fuel assembly. Using this scheme, the lifting force of a prototype fuel assembly is obtained by conducting hydraulic tests on simulated fuel assemblies of equal proportion (1:1) and density. This patented method can accurately measure the dry weight, underwater buoyancy, and lifting force under hydraulic action of a pressurized water reactor fuel assembly, providing a basis for the design of the fuel assembly upper tube seat plate spring.

[0030] 2. The present invention provides a method for measuring the lifting force of a pressurized water reactor fuel assembly. According to this scheme, a plurality of countersunk holes are opened on the lower plate of the simulated core to provide an installation position for the force sensor so that its probe can be located below the support leg of the lower tube seat of the fuel assembly.

[0031] 3. The present invention provides a method for measuring the lifting force of a pressurized water reactor fuel assembly. Using this solution, stainless steel metal pads are installed on the four legs of the fuel assembly lower tube seat, or on the probes of four force sensors. In this way, when measuring pressure loads, the stainless steel metal pads can ensure that the four force sensors are evenly stressed, thereby improving measurement accuracy.

[0032] 4. The present invention provides a method for measuring the lifting force of a pressurized water reactor fuel assembly. This solution employs a steady-state force parallel group scale, which includes four specially made waterproof steady-state force sensors, a 24V DC power supply, a signal processing module, and a display module. The four specially made waterproof steady-state force sensors transmit the detected signals to the signal processing module, which calculates using a corresponding formula model to obtain the detection results, which are ultimately displayed on the display module. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the examples. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be considered as limiting the scope. A person of ordinary skill in the art can also derive other relevant drawings based on these drawings without inventive effort. In the drawings:

[0034] Figure 1 This is a structural schematic diagram of the core lower plate provided by the present invention.

[0035] Markings and corresponding parts names in the accompanying drawings:

[0036] 1-core lower plate, 101-counterbore, 102-support ear, 103-lead channel. DETAILED DESCRIPTION

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0038] In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that these specific details are not necessarily required to practice the present invention. In other embodiments, well-known structures, circuits, materials, or methods are not described in detail to avoid obscuring the present invention.

[0039] Throughout this specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Therefore, appearances of the phrases "one embodiment," "an embodiment," "an example," or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combinations and / or subcombinations. Furthermore, it will be understood by those of ordinary skill in the art that the figures provided herein are for illustrative purposes only and are not necessarily drawn to scale. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0040] In the description of the present invention, the terms "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inside", "outside" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the scope of protection of the present invention.

[0041] Example 1:

[0042] This embodiment 1 provides a method for measuring the lifting force of a pressurized water reactor fuel assembly, such as Figure 1 As shown, the following steps are included:

[0043] A plurality of force sensors are arranged between the contact surface of the lower tube seat of the fuel assembly and the lower plate 1 of the core, and the plurality of force sensors are distributed at the bottom of the lower tube seat of the fuel assembly;

[0044] Then, when there is no water in the test body and the upper tube seat plate spring is in a free state, the pressure load resultant force ∑F is measured. airf ;

[0045] When there is no water in the test body and the upper tube seat plate spring is in a compressed state, the pressure load resultant force ∑F is measured. airp ;

[0046] When the test body is filled with water, the flow rate is zero and the upper tube seat spring is in a compressed state, the pressure load resultant force ∑F is measured. sw ;

[0047] Fill the test body with water, specify the test flow rate and put the upper tube seat spring in the compressed state, and measure the pressure load resultant force ∑F fw ;

[0048] According to ∑F airf ,∑F airp ,∑F sw and ∑F fw , the spring compression force of the upper tube seat plate, the underwater buoyancy and the lifting force under the action of water force are calculated respectively.

[0049] Compared with the existing technology, China has always used theoretical analysis and program calculation methods to estimate the lifting force of fuel assemblies, and no relevant literature reports have been found on the use of experimental measurement methods to obtain the lifting force of fuel assemblies, resulting in the problem that the fuel assembly lifting force calculation lacks real experimental data verification. The present invention provides a method for measuring the lifting force of pressurized water reactor fuel assemblies. By adopting this scheme, the lifting force of the prototype fuel assembly is obtained by conducting hydraulic tests on simulated fuel assemblies; using this patented method, the dry weight, underwater buoyancy and lifting force under hydraulic action of the pressurized water reactor fuel assembly can be accurately measured, providing a basis for the design of the fuel assembly upper tube seat plate spring.

[0050] In the specific scheme, several force sensors are first installed between the contact surface of the fuel assembly lower tube seat and the core lower plate 1. Several of the force sensors are distributed at the bottom of the fuel assembly lower tube seat. In this way, the multiple force sensors can be used to measure under various working conditions. Among them, when weighing the fuel assembly, the steady-state force sensor of this scheme is compared with the measurement data of a calibrated electronic crane scale, and the error is less than 3.5%. After installation, the test body is free of water and the fuel assembly upper tube seat plate spring is in a free state. The pressure load resultant force ∑F is measured. airf (Unit: N); When there is no water in the test body and the spring of the upper tube seat of the fuel assembly is in a compressed state, the pressure load resultant force ∑F is measured airp (Unit: N); When the test body is filled with water, the flow rate is zero, and the spring of the upper tube seat of the fuel assembly is in a compressed state, the pressure load resultant force ∑F is measured sw (Unit: N); The test body is filled with water, the test flow rate is specified, and the spring of the upper tube seat of the fuel assembly is in a compressed state. The pressure load resultant force ∑F is measured. fw (Unit: N); the dry weight of the fuel assembly G (kN) is the pressure load resultant force measured when there is no water in the test body and the fuel assembly upper tube seat plate spring is in a free state, that is, G = ∑F airf ; In the above pressure load resultant force ∑F airf , i.e. the dry weight of the fuel assembly G, the resultant pressure load ∑F airp , pressure load resultant force ∑F sw and pressure load ∑F fw After that, the upper tube seat spring compression force, underwater buoyancy and hydraulic lifting force are calculated. The upper tube seat spring compression force can be obtained from the pressure load resultant force ∑F airp The difference between the dry weight G of the fuel assembly and the underwater buoyancy can be obtained by the pressure load force ∑F airp and pressure load ∑F sw The difference between them is obtained, and the lifting force under hydraulic action can be obtained by the pressure load force ∑F sw and pressure load ∑F fwThe difference between the two values ​​is calculated. By determining the upper tube seat spring compression force, underwater buoyancy, and hydraulic lifting force, it is possible to determine whether the preload force of the newly designed fuel assembly upper tube seat spring meets the requirements. If not, the fuel assembly upper tube seat spring structure design can be optimized and adjusted. Furthermore, a customized steady-state force sensor with matching specifications and dimensions and waterproofing can be developed based on the total weight of the pressurized water reactor fuel assembly and the lower tube seat structure to be measured.

[0051] The above scheme aims to achieve the following: This scheme can be applied to the hydraulic load testing of pressurized water reactor fuel assemblies outside the pile. This test obtains the lifting force of the prototype fuel assembly by conducting hydraulic tests on simulated fuel assemblies of equal proportion (1:1) and density. The method described in this patent can accurately measure the dry weight of the fuel assembly, the underwater buoyancy and the lifting force under hydraulic action, as well as the preload force of the fuel assembly upper tube seat spring, providing a basis for the design of the fuel assembly upper tube seat spring.

[0052] In a further solution, the upper tube seat spring compression force F k The calculation formula is:

[0053] F k =∑F airp -∑F airf .

[0054] In a further embodiment, the underwater buoyancy F g The calculation formula is:

[0055] F g =∑F airp -∑F sw .

[0056] In a further embodiment, the lifting force F under the hydraulic action i The calculation formula is:

[0057] F i =∑F sw -∑F fw .

[0058] In a further embodiment, four force sensors are provided, each located at the four legs of the fuel assembly lower tube seat. By placing the force sensors at the legs of the lower tube seat, the pressure transmitted from the fuel assembly can be measured in real time, thereby improving measurement accuracy.

[0059] In a further solution, the force sensor is a waterproof steady-state force sensor.

[0060] In a further embodiment, the core lower plate 1 is evenly distributed with several countersunk holes 101, and the force sensors are installed at these countersunk holes 101. The core lower plate 1 has reserved installation locations and depths for the force sensors, allowing them to be directly mounted on the countersunk holes 101, with their probes extending out of the holes. Four water flow holes are also evenly distributed in the center of the core lower plate 1.

[0061] A further solution is to facilitate the individual extraction of leads. Several lugs 102 extend from the circumferential ends of the core lower plate 1. Each lug 102 has a lead hole 103 formed within it. One end of the lead hole 103 extends through the end of the lug 102, and the other end of the lead hole 103 communicates with a corresponding countersunk hole 101. In this solution, the simulated core lower plate 1 is specially prepared, with a lug 102 with a lead hole 103 extending from each of its four sides. These lugs are used to extract the signal wires from the force sensors, and the lead hole diameter does not exceed 7mm. The four countersunk holes 101 for the steady-state force sensors (11mm high, 20mm outer diameter) are 9mm deep and have a diameter of 20.4mm. The signal lines of the four steady-state force sensors are led out from the lead channel 103, then wrapped by the double-layer flange gasket on the DN100 interface pipe on the test cylinder and led out to the junction box outside the test cylinder. The output load resultant force signal is incorporated into the data acquisition.

[0062] A further approach involves designing a stainless steel metal backing plate thick enough to withstand the weight of the fuel assembly without visible deformation, to improve the accuracy of test data measurements. This plate is positioned directly above the probes of several force sensors and connected to the probes of these force sensors or to the four legs of the fuel assembly lower tube holder. The thickness of the plate is ≥ 2mm. In this approach, the plate is flush with the simulated core lower plate 1 and can be installed on the four legs of the fuel assembly lower tube holder or on the probes of the four force sensors. This ensures that the four force sensors are evenly stressed during pressure load measurements, improving measurement accuracy.

[0063] A further embodiment further includes a signal processing module and a display module connected to the force sensors. The signal processing module is configured to receive and process the force sensor signals, and the display module is configured to display the processing results of the signal processing module. In this embodiment, a steady-state force parallel scale can be used. The steady-state force parallel scale includes four specially designed waterproof steady-state force sensors, a 24V DC power supply, a signal processing module, and a display module. The four specially designed waterproof steady-state force sensors transmit the detected signals to the signal processing module, which calculates the results using the corresponding formula model to obtain the detection results, and ultimately displays the detection results on the display module.

[0064] Example 2:

[0065] This embodiment 2 provides a specific measurement principle and steps of a method for measuring the lifting force of a pressurized water reactor fuel assembly.

[0066] The present invention primarily utilizes four specially designed waterproof steady-state force sensors, evenly distributed at the contact surface between the four legs of the fuel assembly lower tube seat and the lower core plate 1. The sensors record the pressure loads under four different test conditions: air (no water) with the upper tube seat leaf spring in a free state, air (no water) with the upper tube seat leaf spring in a compressed state, static water (water flow rate of zero) with the upper tube seat leaf spring in a compressed state, and dynamic water (specified test flow rate) with the upper tube seat leaf spring in a compressed state (see Table 1 for a detailed table of raw test data). Using the formulas listed in Table 2, the dry weight of the fuel assembly, underwater buoyancy, hydraulic lifting force, and the preload force of the fuel assembly upper tube seat leaf spring are calculated. The steady-state force parallel scale includes four specially designed waterproof steady-state force sensors, a 24V DC power supply, a signal processing module, and a display module. Through the above-mentioned device and corresponding measurement steps, the lifting force of the prototype fuel assembly can be obtained by conducting hydraulic tests on the simulated fuel assembly; the dry weight, underwater buoyancy and lifting force under hydraulic action of the pressurized water reactor fuel assembly can be accurately measured by using this patented method, providing a basis for the design of the fuel assembly upper tube seat plate spring.

[0067] The specific steps and principles are as follows:

[0068] Four specially designed waterproof steady-state force sensors were evenly distributed at the contact surfaces between the four legs of the fuel assembly lower tube seat and the core lower plate 1. These sensors were installed at countersunk holes 101 in the simulated core lower plate 1, with their probes extending out of these holes. Stainless steel metal backing plates were installed on the four legs of the fuel assembly lower tube seat. Measurements were then carried out. The four steady-state force sensors measured the resulting pressure loads when the test body was free of water and the fuel assembly upper tube seat leaf spring was in a free state. The four steady-state force sensors also measured the resulting pressure loads when the test body was free of water and the fuel assembly upper tube seat leaf spring was in a compressed state. Finally, the four steady-state force sensors measured the resulting pressure loads when the test body was filled with water and the pump was off (water flow rate was 0 m / s), as shown in Table 1.

[0069]

[0070]

[0071] Table 1 Fuel assembly out-of-pile hydraulic load test measurement data record

[0072] That is, the steps of measuring by the force sensor are as follows:

[0073] Step 1: When there is no water in the test body and the fuel assembly upper tube seat spring is in a free state, use four steady-state force sensors to measure the pressure load resultant force ∑F airf (Unit: N);

[0074] Step 2: Under the condition that there is no water in the test body and the spring of the upper tube seat of the fuel assembly is in a compressed state, the four steady-state force sensors measure the pressure load resultant force ∑F airp (Unit: N);

[0075] Step 3: Fill the test body with water and stop the pump (water flow rate is 0m / s) and measure the pressure load resultant force ∑F using four steady-state force sensors. sw (Unit: N);

[0076] Step 4: Under the condition that the water in the test body is flowing, the four steady-state force sensors measure the pressure load resultant force, ∑F fw (Unit: N).

[0077] After obtaining the above data, the force sensor can transmit the corresponding data to the signal processing module for data processing, including the following steps:

[0078] The spring compression force F of the upper tube seat plate of the simulation component k Calculation formula:

[0079] F k =∑F airp -∑F airf

[0080] Simulate the buoyancy F of the component underwater g Calculation formula:

[0081] F g =∑F airp -∑F sw

[0082] The measured value of the lifting force F on the simulated component under the impact of water flow i Calculation formula:

[0083] F i =∑F sw -∑F fw

[0084] The data processing is shown in Table 2:

[0085]

[0086] Table 2 Fuel assembly out-of-pile hydraulic load test results

[0087] Finally, after obtaining the compression force of the upper tube seat plate spring, underwater buoyancy, and lifting force under hydraulic action, it can be determined whether the preload force of the fuel assembly upper tube seat plate spring meets the requirements. If not, the structural design of the fuel assembly upper tube seat plate spring is optimized and adjusted.

[0088] The above implementation scheme provides a method for measuring the lifting force of a pressurized water reactor fuel assembly. First, the lifting force of a prototype fuel assembly can be obtained by conducting hydraulic tests on simulated fuel assemblies of equal proportion (1:1) and equal density. This patented method can accurately measure the dry weight, underwater buoyancy, and lifting force of a pressurized water reactor fuel assembly under hydraulic pressure, providing a basis for the design of the spring for the upper tube seat of the fuel assembly. Second, several countersunk holes are opened on the lower plate of the simulated core to provide an installation position for the force sensor so that its probe can be located below the support leg of the lower tube seat of the fuel assembly. Third, stainless steel metal pads are installed on the four support legs of the lower tube seat of the fuel assembly, or on the probes of the four force sensors. In this way, when measuring the pressure load, the stainless steel metal pads can make the four force sensors evenly stressed, thereby improving the measurement accuracy.

[0089] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for measuring the lifting force of a pressurized water reactor fuel assembly, characterized in that: The following steps are involved: A plurality of force sensors are arranged between the contact surface of the lower tube seat of the fuel assembly and the lower plate (1) of the core, and the plurality of force sensors are distributed at the bottom of the lower tube seat of the fuel assembly; Then, when there is no water in the test body and the upper tube seat plate spring is in a free state, the pressure load resultant force ∑F is measured. airf ; When there is no water in the test body and the upper tube seat plate spring is in a compressed state, the pressure load resultant force ∑F is measured. airp ; When the test body is filled with water, the flow rate is zero and the upper tube seat spring is in a compressed state, the pressure load resultant force ∑F is measured. sw ; Fill the test body with water, specify the test flow rate and put the upper tube seat spring in the compressed state, and measure the pressure load resultant force ∑F fw ; According to ∑F airf ,∑F airp ,∑F sw and ∑F fw , the spring compression force of the upper tube seat plate, the underwater buoyancy and the lifting force under the action of water force are calculated respectively.

2. The method for measuring the lifting force of a pressurized water reactor fuel assembly according to claim 1, wherein: The upper tube seat spring compression force F k The calculation formula is: F k =∑F airp -∑F airf 。 3. The method for measuring the lifting force of a pressurized water reactor fuel assembly according to claim 1, wherein: The underwater buoyancy F g The calculation formula is: F g =∑F airp -∑F sw 。 4. The method for measuring the lifting force of a pressurized water reactor fuel assembly according to claim 1, wherein: The lifting force F under the hydraulic action i The calculation formula is: F i =∑F sw -∑F fw 。 5. The method for measuring the lifting force of a pressurized water reactor fuel assembly according to claim 1, wherein: There are four force sensors, which are respectively arranged at the four legs of the lower tube seat of the fuel assembly.

6. The method for measuring the lifting force of a pressurized water reactor fuel assembly according to claim 1, wherein: The force sensor is a waterproof steady-state force sensor.

7. The method for measuring the lifting force of a pressurized water reactor fuel assembly according to claim 1, wherein: A plurality of countersunk holes (101) are evenly distributed on the core lower plate (1), and the force sensors are installed at the positions of the countersunk holes (101).

8. The method for measuring the lifting force of a pressurized water reactor fuel assembly according to claim 7, characterized in that: A plurality of lugs (102) are respectively extended from the peripheral end of the core lower plate (1), and a lead hole (103) is opened inside each lug (102). One end of the lead hole (103) is connected to the end of the lug (102), and the other end of the lead hole (103) is connected to a corresponding countersunk hole (101).

9. The method for measuring the lifting force of a pressurized water reactor fuel assembly according to claim 1, wherein: A stainless steel metal backing plate is provided directly above the probes of the force sensors, and the stainless steel metal backing plate is connected to the probes of the force sensors or to the four legs of the lower tube seat of the fuel assembly; The thickness of the stainless steel metal backing plate is ≥2mm.

10. The method for measuring the lifting force of a pressurized water reactor fuel assembly according to claim 1, wherein: It also includes a signal processing module and a display module connected to the plurality of force sensors. The signal processing module is used to receive and process the signals of the force sensors, and the display module is used to display the processing results of the signal processing module.

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