Pressurized water reactor fuel assembly lifting force measuring method

Abstract

The invention discloses a pressurized water reactor fuel assembly lifting force measurement method, and relates to the technical field of pressurized water reactor measurement, and the method comprises the following steps: arranging a plurality of force sensors between contact surfaces of a fuel assembly lower tube seat and a reactor core lower plate; when no water exists in the test body and the upper tube seat plate spring is in a free state, when no water exists in the test body and the upper tube seat plate spring is in a compressed state, the test body is filled with water and the flow velocity is below zero, and when the test body is filled with water and the specified test flow, the resultant force of pressure loads is measured; and respectively calculating to obtain the spring pressing force of the upper tube seat plate, the underwater buoyancy and the lifting force under the hydraulic action. By adopting the scheme, the lifting force of the prototype fuel assembly is obtained by carrying out a hydraulic test on the equivalent-proportion (1: 1) and equal-density simulated fuel assembly; by means of the method, the dry weight, the underwater buoyancy and the lifting force under the hydraulic action of the pressurized water reactor fuel assembly can be accurately measured, and a basis is provided for design of an upper tube seat plate spring of the fuel assembly.

Description

Technical Field

[0001] The 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 the coolant flows through the core of a pressurized water reactor, it exerts a strong force on the fuel assembly, causing axial and circumferential deformation of the fuel assembly, which may affect the safety and economy of the reactor. In engineering, the lifting force of the 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 gravity and buoyancy of the fuel assembly. Under normal operating conditions, the fuel assembly is not allowed to move due to the flow of coolant. In order to prevent the fuel assembly from floating up within the operating flow range of the reactor, a compression spring structure is designed on the upper tube seat of the fuel assembly to provide a compression force to fix the fuel assembly.

[0003] If the clamping force of the upper tube seat clamping spring structure is too large, the fuel assembly is easily damaged. If it is too small, the fuel assembly will float. Therefore, the fuel assembly lifting force calculation must be performed in the reactor thermal hydraulic design to determine whether the design of the fuel assembly clamping spring meets the requirements of relevant standards. In the past, China has always used theoretical analysis and program calculation methods to estimate the fuel assembly lifting force, and has not found any relevant literature reports on the use of experimental measurement methods to obtain the fuel assembly lifting force, resulting in a lack of real experimental data verification for the fuel assembly lifting force calculation. Summary of the invention

[0004] The present invention aims to solve the problem of lack of real test data verification in the lifting force calculation of fuel assemblies in the prior art, and aims to provide a method for measuring the lifting force of pressurized water reactor fuel assemblies. By adopting this scheme, hydraulic tests are carried out on simulated fuel assemblies of equal proportion (1:1) and equal density to obtain the lifting force of the prototype 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 upper tube seat plate spring of the fuel assembly.

[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, and the plurality of force sensors are evenly 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 plate spring is in a compressed state, the pressure load resultant force ∑F is measured. sw ;

[0011] The test body is filled with water, the test flow is specified, and the upper tube seat plate spring is in a compressed state. The pressure load resultant force ∑F is measured. 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 hydraulic force are calculated respectively.

[0013] Compared with the prior art, China has always used theoretical analysis and program calculation methods to estimate the lifting force of fuel assemblies, and has not found any relevant literature reports on the use of experimental measurement methods to obtain the lifting force of fuel assemblies, resulting in the problem of lack of real experimental data verification in the calculation of the lifting force of fuel assemblies. The present invention provides a method for measuring the lifting force of a pressurized water reactor fuel assembly. By adopting this scheme, the lifting force of a prototype fuel assembly is obtained by conducting hydraulic tests on simulated fuel assemblies; the dry weight, underwater buoyancy and lifting force under hydraulic action of a pressurized water reactor fuel assembly can be accurately measured by using this patented method, providing a basis for the design of the tube seat plate spring on the fuel assembly.

[0014] In the specific scheme, firstly, a plurality of force sensors are arranged between the contact surface of the lower tube seat of the fuel assembly and the lower plate of the core, and the plurality of force sensors are evenly distributed at the bottom of the lower tube seat of the fuel assembly; thus, through the plurality of force sensors, measurements can be performed 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 the calibrated electronic crane scale at the same time, and the error is less than 3.5%. After the installation is completed, the pressure load resultant force ∑F is measured when there is no water in the test body and the plate spring of the upper tube seat of the fuel assembly is in a free state. 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); When 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 upper tube seat spring of the fuel assembly 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 force ∑F sw and pressure load force ∑F fw After that, the upper tube seat plate spring compression force, underwater buoyancy and hydraulic lifting force are calculated and deduced. The upper tube seat plate spring compression force can be obtained from the pressure load combined 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 force ∑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 force ∑F fw After obtaining the upper tube seat plate spring compression force, underwater buoyancy and hydraulic lifting force, it can be determined whether the preload force of the newly designed fuel assembly upper tube seat plate spring meets the requirements. If not, the fuel assembly upper tube seat plate spring structure design is optimized and adjusted. In addition, according to the total weight of the pressurized water reactor fuel assembly to be measured and the lower tube seat structure type, a steady-state force sensor with matching specifications and dimensions and waterproof function can be customized.

[0015] The above scheme aims to achieve: This scheme can be applied to the hydraulic load test of the fuel assembly outside the pressurized water reactor. The test is to obtain the lifting force of the prototype fuel assembly by conducting a hydraulic test on the simulated fuel assembly. According to the method described in this patent, the dry weight of the fuel assembly, the underwater buoyancy and the lifting force under the action of hydraulic force, and the preload force of the upper tube seat plate spring of the fuel assembly can be accurately measured, providing a basis for the design of the upper tube seat plate spring of the fuel assembly.

[0016] In a further embodiment, 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 solution, there are four force sensors, which are respectively arranged at four legs of the lower tube seat of the fuel assembly. By arranging the force sensors at the legs of the lower tube seat, the pressure transmitted from the fuel assembly can be measured in real time to improve the 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 are extended from the circumferential ends of the lower core plate, each of which has a lead hole opened inside, one end of the lead hole is connected to the end of the lug, and the other end of the lead 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 hole is extended from each of the four surfaces of the simulated core lower plate, which is used to lead out the signal line of the force sensor, and the lead 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 Φ20.4mm in diameter. After the signal lines of the four steady-state force sensors are led out from the lead hole, they are wrapped with the double-layer flange gasket on the DN100 interface pipe on the test cylinder and led out to the external junction box of the test cylinder, and the output load resultant force signal is incorporated into the data acquisition.

[0026] A further solution is to design a stainless steel metal pad with a thickness that can bear the weight of the fuel assembly without visible deformation to improve the accuracy of test data measurement. A stainless steel metal pad is set just above the probes of several force sensors, and the stainless steel metal pad is connected to the probes of several force sensors or to the four legs of the lower tube seat of the fuel assembly; the thickness of the stainless steel metal pad is ≥2mm. In this solution, the stainless steel metal pad is flush with the simulated core lower plate, and the stainless steel metal pad can be installed on the four legs of the lower tube seat of the fuel assembly, or on the probes of four force sensors. In this way, when measuring the pressure load, the four force sensors can be evenly stressed through the stainless steel metal pad, which can improve the measurement accuracy.

[0027] A further solution also includes a signal processing module and a display module connected to the force sensors, wherein 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. In this solution, a steady-state force parallel group scale can be used, which includes 4 special waterproof steady-state force sensors, a 24V DC power supply, a signal processing module and a display module. The 4 special waterproof steady-state force sensors transmit the detected signals to the signal processing module, and the signal processing module calculates through the corresponding formula model to obtain the detection results, and finally displays the detection results through 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. 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; 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 upper tube seat plate spring of the fuel assembly.

[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 foot 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. According to this scheme, a stainless steel metal pad is installed on the four legs of the lower tube seat of the fuel assembly, or on the probes of four force sensors. Thus, when measuring the pressure load, the stainless steel metal pad can make the four force sensors evenly stressed, thereby improving the measurement accuracy.

[0032] 4. The present invention provides a method for measuring the lifting force of a pressurized water reactor fuel assembly. By adopting this scheme, a steady-state force parallel group scale can be used. The steady-state force parallel group scale includes 4 special waterproof steady-state force sensors, a 24V DC power supply, a signal processing module and a display module. The 4 special waterproof steady-state force sensors transmit the detected signals to the signal processing module, and the signal processing module calculates through the corresponding formula model to obtain the detection results, and finally displays the detection results through 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 embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

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

[0035] Marks and corresponding parts names in the attached drawings:

[0036] 1-core lower plate, 101-counter hole, 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 embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0038] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is apparent to one of ordinary skill in the art that these specific details are not necessarily employed to practice the present invention. In other embodiments, in order to avoid obscuring the present invention, well-known structures, circuits, materials, or methods are not specifically described.

[0039] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment," "an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. In addition, it will be appreciated by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0040] In the description of the present invention, the directions or positional relationships indicated by terms such as “front”, “rear”, “left”, “right”, “up”, “down”, “vertical”, “horizontal”, “high”, “low”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They 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] Embodiment 1:

[0042] This embodiment 1 provides a method for measuring the lifting force of a pressurized water reactor fuel assembly. 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 evenly 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 plate spring is in a compressed state, the pressure load resultant force ∑F is measured. sw ;

[0047] The test body is filled with water, the test flow is specified, and the upper tube seat plate spring is in a compressed state. The pressure load resultant force ∑F is measured. 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 hydraulic force are calculated respectively.

[0049] Compared with the prior art, China has always used theoretical analysis and program calculation methods to estimate the lifting force of fuel assemblies, and has not found any relevant literature reports on the use of experimental measurement methods to obtain the lifting force of fuel assemblies, resulting in the problem of lack of real experimental data verification in the calculation of the lifting force of fuel assemblies. The present invention provides a method for measuring the lifting force of a pressurized water reactor fuel assembly. By adopting this scheme, the lifting force of a prototype fuel assembly is obtained by conducting hydraulic tests on simulated fuel assemblies; the dry weight, underwater buoyancy and lifting force under hydraulic action of a pressurized water reactor fuel assembly can be accurately measured by using this patented method, providing a basis for the design of the tube seat plate spring on the fuel assembly.

[0050] In the specific scheme, firstly, 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 evenly distributed at the bottom of the lower tube seat of the fuel assembly; thus, through the plurality of force sensors, measurements can be performed 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 the calibrated electronic crane scale at the same time, and the error is less than 3.5%. After the installation is completed, the pressure load resultant force ∑F is measured when there is no water in the test body and the upper tube seat plate spring of the fuel assembly is in a free state. 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); When 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 upper tube seat spring of the fuel assembly 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 force ∑F sw and pressure load force ∑F fw After that, the upper tube seat plate spring compression force, underwater buoyancy and hydraulic lifting force are calculated. The upper tube seat plate spring compression force can be obtained by the pressure load combined 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 force ∑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 force ∑F fwAfter obtaining the upper tube seat plate spring compression force, underwater buoyancy and hydraulic lifting force, it can be determined whether the preload force of the newly designed fuel assembly upper tube seat plate spring meets the requirements. If not, the fuel assembly upper tube seat plate spring structure design is optimized and adjusted. In addition, according to the total weight of the pressurized water reactor fuel assembly to be measured and the lower tube seat structure type, a steady-state force sensor with matching specifications and dimensions and waterproof function can be customized.

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

[0052] In a further embodiment, 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 solution, there are four force sensors, which are respectively arranged at four legs of the lower tube seat of the fuel assembly. By arranging the force sensors at the legs of the lower tube seat, the pressure transmitted from the fuel assembly can be measured in real time to improve the measurement accuracy.

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

[0060] In a further solution, a plurality of countersunk holes 101 are evenly distributed on the core lower plate 1, and the force sensor is installed at the position of the countersunk hole 101. The installation position and depth of the force sensor are reserved in the core lower plate 1, and the force sensor is directly installed on the countersunk hole 101, and its probe extends out of the countersunk hole 101. Four water flow holes are also evenly distributed in the middle of the core lower plate 1.

[0061] A further solution is that, in order to facilitate the individual lead-out of the leads, a plurality of lugs 102 are extended from the circumferential ends of the core lower plate 1, and a lead-wire hole 103 is opened inside each lug 102. One end of the lead-wire hole 103 is connected to the end of the lug 102, and the other end of the lead-wire hole 103 is connected to a corresponding countersunk hole 101. In this solution, the simulated core lower plate 1 is specially prepared, and a lug 102 with a lead-wire hole 103 is extended from each of the four surfaces of the simulated core lower plate, which is used to lead out the signal line of the force sensor, and the lead-wire hole diameter does not exceed 7mm. The four countersunk holes 101 for placing steady-state force sensors (11mm high, 20mm outer diameter) are 9mm deep and have a hole diameter of Φ20.4mm. The signal lines of the four steady-state force sensors are led out from the lead channel 103, and 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 solution is to design a stainless steel metal pad with a thickness that can bear the weight of the fuel assembly without visible deformation to improve the accuracy of test data measurement. A stainless steel metal pad is arranged directly above the probes of several force sensors, and the stainless steel metal pad is connected to the probes of several force sensors or to the four legs of the lower tube seat of the fuel assembly; the thickness of the stainless steel metal pad is ≥2mm. In this solution, the stainless steel metal pad is flush with the lower plate 1 of the simulated core, and the stainless steel metal pad can be installed on the four legs of the lower tube seat of the fuel assembly, or on the probes of four force sensors. In this way, when measuring the pressure load, the four force sensors can be evenly stressed through the stainless steel metal pad, which can improve the measurement accuracy.

[0063] A further solution also includes a signal processing module and a display module connected to the force sensors, wherein 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. In this solution, a steady-state force parallel group scale can be used, which includes 4 special waterproof steady-state force sensors, a 24V DC power supply, a signal processing module and a display module. The 4 special waterproof steady-state force sensors transmit the detected signals to the signal processing module, and the signal processing module calculates through the corresponding formula model to obtain the detection results, and finally displays the detection results through the display module.

[0064] Embodiment 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 mainly utilizes 4 special waterproof steady-state force sensors evenly distributed at the contact surface between the four legs of the lower tube seat of the fuel assembly and the lower core plate 1, and records the pressure load on the steady-state force sensor under four different test conditions: air (no water) + upper tube seat plate spring in a free state, air (no water) + upper tube seat plate spring in a compressed state, static water (water flow rate is 0) + upper tube seat plate spring in a compressed state, and dynamic water (specified test flow) + upper tube seat plate spring in a compressed state (see Table 1 for the test measurement original data record table), and after conversion by the calculation formula listed in Table 2, the dry weight of the fuel assembly, the underwater buoyancy and the lifting force under the hydraulic action, and the preload force of the upper tube seat plate spring of the fuel assembly can be obtained respectively. The steady-state force parallel group scale includes 4 special 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 simulated fuel assemblies; 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 upper tube seat plate spring of the fuel assembly.

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

[0068] Four special waterproof steady-state force sensors are evenly distributed at the contact surface between the four legs of the lower tube seat of the fuel assembly and the lower core plate 1. The four special waterproof steady-state force sensors are installed at the countersunk hole 101 of the simulated lower core plate 1, and the probes of the force sensors extend out of the countersunk hole 101; stainless steel metal pads are installed on the four legs of the lower tube seat of the fuel assembly. Then the measurement steps are started. The four steady-state force sensors are used to measure the pressure load resultant force when there is no water in the test body and the plate spring of the upper tube seat of the fuel assembly is in a free state. The four steady-state force sensors are used to measure the pressure load resultant force when there is no water in the test body and the plate spring of the upper tube seat of the fuel assembly is in a compressed state. The four steady-state force sensors are used to measure the pressure load resultant force when the test body is filled with water and the pump is stopped (the water flow rate is 0m / 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 above-mentioned steps of measuring by the force sensor are:

[0073] Step 1: When there is no water in the test body and the upper tube seat spring of the fuel assembly is in a free state, use 4 steady-state force sensors to measure the pressure load 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 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: When the water in the test body is flowing, the four steady-state force sensors measure the pressure load 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, the underwater buoyancy and the lifting force under the action of hydraulic force, it can be judged whether the preload force of the upper tube seat plate spring of the fuel assembly meets the requirements. If it does not meet the requirements, the structural design of the upper tube seat plate spring of the fuel assembly is optimized and adjusted.

[0088] The method for measuring the lifting force of a pressurized water reactor fuel assembly provided by the above implementation scheme, first: can obtain the lifting force of the prototype fuel assembly by conducting hydraulic tests on simulated fuel assemblies of equal proportion (1:1) and equal density; 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 plate spring of the upper tube seat of the fuel assembly. Second: by opening a number of countersunk holes on the lower plate of the simulated core, it is used to provide an installation position for the force sensor so that its probe can be located below the support foot of the lower tube seat of the fuel assembly. Third: by installing stainless steel metal pads on the four support feet 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 four force sensors can be evenly stressed through the stainless steel metal pads, which can improve 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 evenly 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 plate spring is in a compressed state, the pressure load resultant force ∑F is measured. sw ; The test body is filled with water, the test flow is specified, and the upper tube seat plate spring is in a compressed state. The pressure load resultant force ∑F is measured. 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 hydraulic force are calculated respectively.

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

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

7. A method for measuring lifting force of a pressurized water reactor fuel assembly according to claim 1, characterized in that: A plurality of countersunk holes (101) are evenly distributed on the core lower plate (1), and the force sensor is installed at the position of the countersunk holes (101).

8. A method for measuring 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 wire channel (103) is opened inside each lug (102), one end of the lead wire channel (103) is connected to the end of the lug (102), and the other end of the lead wire channel (103) is connected to a corresponding countersunk hole (101).

9. A method for measuring lifting force of a pressurized water reactor fuel assembly according to claim 1, characterized in that: A stainless steel metal pad is arranged directly above the probes of the force sensors, and the stainless steel metal pad 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. A method for measuring lifting force of a pressurized water reactor fuel assembly according to claim 1, characterized in that: It also includes a signal processing module and a display module connected to the 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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