A method, device, equipment and medium for controlling rod drop of a control rod

Abstract

The application provides a control rod falling control method, device, equipment and medium, the control rod falling control method comprises the following steps: obtaining current state data of each control rod, and fusing the earthquake acceleration and the corresponding falling rod acceleration in the current state data to obtain fusion state data; according to the fusion state data, the lateral deformation displacement of each control rod is obtained by a preset fluid motion equation; according to the lateral deformation displacement, the friction between each control rod and the corresponding guide pipe is calculated to obtain the total friction of all control rods; the total friction is used as a load term to update the fluid motion equation, and the falling rod parameters are calculated by the updated fluid motion equation according to the fusion state data, and the control rod is controlled according to the falling rod parameters. Through the control rod falling control method, device, equipment and medium provided by the application, the technical problem that the falling rod process brings unpredictable risks to the safety of the reactor is solved.

Description

Technical Field

[0001] This invention relates to the field of nuclear power, and more particularly to a method, apparatus, equipment, and medium for controlling the dropping of control rods. Background Technology

[0002] The control rod drive line is the core system of nuclear reactor safety control, and its operational reliability directly affects reactor safety. In accident conditions, the control rods must fall rapidly under gravity to achieve emergency shutdown. During this process, the control rod falling time, speed, and other parameters are crucial safety indicators that must be precisely monitored and effectively intervened in case of anomalies to ensure timely and reliable triggering of the shutdown function. However, under extreme load conditions such as earthquakes, the control rod falling process becomes exceptionally complex. Due to the minute gap between the control rods and their guide tubes, structural vibrations caused by earthquakes can lead to random lateral collisions between the two.

[0003] Current technologies for controlling the rod dropping process are mostly based on kinematic models under ideal conditions or dynamic models that only consider simple friction, failing to effectively incorporate the random collision effects caused by earthquakes and the resulting dynamic friction. This leads to significant deviations between the rod dropping parameters predicted by traditional models and the actual situation under real earthquake conditions, making it impossible to accurately determine the rod dropping status. This could delay necessary intervention or issue inappropriate control commands based on incorrect parameters, posing unpredictable risks to reactor safety. Therefore, improvements are needed. Summary of the Invention

[0004] This invention provides a method, apparatus, equipment, and medium for controlling the dropping of control rods, in order to solve the technical problem that the dropping process poses unpredictable risks to reactor safety.

[0005] The present invention provides a method for controlling the dropping of a control rod, comprising:

[0006] The current state data of each control rod is obtained, and the seismic acceleration is fused with the corresponding falling rod acceleration in the current state data to obtain the fused state data of each control rod. Based on the fusion state data, the lateral deformation displacement of each control rod due to seismic load is calculated using a preset fluid motion equation. Based on the lateral deformation displacement of each control rod, calculate the frictional force generated by the collision between each control rod and the corresponding guide tube to obtain the total frictional force of all control rods. The total friction force is used as a load term to update the fluid motion equation. Based on the fusion state data, the drop bar parameters are calculated using the updated fluid motion equation, and the control rod is controlled according to the drop bar parameters.

[0007] In one embodiment of the present invention, the fluid motion equation is constructed by performing fluid-structure interaction analysis on the control rod during the dropping process, including nonviscous conservative fluid force, viscous nonconservative fluid resistance, pressure difference resistance, and fluid inertial force. The fluid motion equation includes fluid motion equations for lateral vibration and vertical drop.

[0008] In one embodiment of the present invention, the calculation formula for the fluid motion equation is as follows:

[0009] in, , All of these represent the vertical displacement of the control rod. , These are the cross-sectional bending stiffnesses of the control rod assembly, which consists of the drive rod and the control rod, in two lateral directions. , , These represent the displacement components of the control rod in the vertical direction and the two lateral directions, respectively. The time of the bat drop. , , These represent the viscous nonconservative fluid resistances acting on the control rod in the vertical direction and the two lateral directions, respectively. , These are the nonviscous conservative fluid forces acting in the two transverse directions of the control rod. The unit mass of the control rod assembly, which consists of the drive rod and the control rod. It is the acceleration due to gravity. The pressure drag is caused by the fluid pressure gradient acting on the control rod. The fluid pressure borne at the top of the control rod assembly, which consists of the drive rod and the control rod. This refers to the top area of ​​the control rod assembly, which consists of the drive rod and the control rod. For the unit mass of the fluid, To control the acceleration of the falling rod, For fluid inertial force, The axial force at the top of the control rod assembly, which consists of the drive rod and the control rod. To control the distance between the bottom end of the control rod and the bottom end of the corresponding guide tube before the rod drops.

[0010] In one embodiment of the present invention, the calculation formula for the nonviscous conservative fluid force is as follows:

[0011]

[0012] in, , The first The control rod has two lateral directions of nonviscous conservative fluid forces. For fluid density, The control rod number, The total number of control rods, , The first The, the The radius of each control rod, , , , All are the first The control stick to the first The coupling effect coefficient of each control rod The fluid velocity on the surface of the control rod in the vertical direction. , The first The control stick to the first The lateral deformation displacement of the control rod in two lateral directions.

[0013] In one embodiment of the present invention, the step of calculating the frictional force generated by the collision between each control rod and the corresponding guide tube based on the lateral deformation displacement of each control rod, so as to obtain the total frictional force of all control rods, includes: Based on the lateral deformation displacement of each control rod, the collision force generated between each control rod and the corresponding guide tube due to the collision is calculated using a preset collision force model. Based on the collision force between each control rod and its corresponding guide tube, the total friction force generated by the collision of all control rods is calculated using a preset Coulomb friction model.

[0014] In one embodiment of the present invention, the calculation formula for the collision force model is as follows:

[0015] in, For the first The collision force between each control rod and its corresponding guide tube This is the collision stiffness coefficient. This refers to the design clearance value between the control rod and the corresponding guide tube. For the first Lateral deformation displacement of each control rod.

[0016] In one embodiment of the present invention, the calculation formula of the Coulomb friction model is as follows:

[0017] in, For the total friction force, For the first The coefficient of friction between each control rod and its corresponding guide tube.

[0018] In one embodiment of the present invention, the drop bar control method further includes: determining whether the control bar collides with the bottom end of the corresponding guide tube, and when colliding, calculating the drop bar impact force of the control bar based on the drop bar speed in the drop bar parameters and the vertical displacement of the control bar after colliding with the corresponding guide tube, through a preset impact calculation model.

[0019] In one embodiment of the present invention, the formula for calculating the impact force of the falling rod is as follows:

[0020] in, For the first The impact force of the control rod falling. , The first Stiffness and damping of each control rod and its corresponding guide tube during impact. , The first The vertical displacement and drop speed of each control rod.

[0021] The present invention also provides a control device for controlling the dropping of a control rod, comprising: The data fusion module is used to acquire the current state data of each control rod and fuse the seismic acceleration with the corresponding drop rod acceleration in the current state data to obtain the fused state data of each control rod. The displacement calculation module is used to calculate the lateral deformation displacement of each control rod due to seismic load based on the fused state data and a preset fluid motion equation. The friction calculation module is used to calculate the friction force generated between each control rod and the corresponding guide tube due to collision based on the lateral deformation displacement of each control rod, so as to obtain the total friction force of all control rods. The drop bar control module is used to update the fluid motion equation with the total friction force as a load term, calculate the drop bar parameters based on the updated fluid motion equation according to the fusion state data, and control the control bar according to the drop bar parameters.

[0022] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the control rod dropping control method.

[0023] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the control rod dropping control method.

[0024] The beneficial effects of this invention are as follows: By directly integrating seismic loads into the control rod state and driving dynamic calculations, the random collision process between the control rod and the guide tube under seismic conditions can be accurately simulated. Based on the fused state data, the lateral deformation displacement is calculated through a preset fluid motion equation, and then the frictional force generated by random collisions is solved. This total frictional force is fed back to update the fluid motion equation, achieving precise quantification of the complex frictional resistance caused by earthquakes during the rod drop process. The calculated rod drop parameters, such as drop time and velocity, more realistically reflect the actual rod drop behavior under seismic conditions. This significantly improves the accuracy of rod drop parameter prediction and its applicability to real-world conditions, providing a technical basis for judging the state and controlling the control rod based on more reliable rod drop parameters under extreme loads such as earthquakes, effectively compensating for the safety risks inherent in existing technologies that ignore random collision effects. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0026] In the attached diagram: Figure 1 This is a schematic diagram of a control rod drive line structure provided in an embodiment of the present invention; Figure 2 This is a flowchart of a method for calculating the control rod dropping parameters according to an embodiment of the present invention; Figure 3 This is a schematic diagram of a device for calculating the control rod dropping parameters provided in one embodiment of the present invention; Figure 4 This is a schematic diagram of an electronic device provided in one embodiment of the present invention. Detailed Implementation

[0027] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0028] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0029] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0030] This invention discloses a control rod drop control method applicable to nuclear power plant reactor safety shutdown systems, particularly for extreme environmental load conditions such as earthquakes. During an earthquake, the reactor's control rod drive line structure vibrates, causing irregular lateral collisions and friction between the control rods, which are normally in a small-clearance fit, and their guide tubes. This dynamically changing friction significantly alters the control rod's drop behavior, affecting its drop parameters. The aforementioned drop control method provides accurate drop parameters to the safety system by precisely sensing the state and calculating parameters of the drop process, including the earthquake impact. This ensures reliable triggering and completion of shutdown actions in emergency situations, thereby addressing the potential risks of inaccurate predictions and control lags in existing control methods when facing random collision effects.

[0031] Please see Figure 1 The control rod drive line structure, from top to bottom, includes: a drive mechanism 110, mounted on the pressure vessel top cover 130, responsible for the lifting and lowering of the control rods; a control rod assembly 120, consisting of a drive rod and a control rod, extending downward from the drive mechanism 110 and forming the moving part during rod lowering; an upper control rod guide tube 140, passing through the top cover 130 and fixed to the upper support plate 150, providing initial guidance for the control rod assembly 120; a lower control rod guide tube 160, fixed to the core upper plate 170, providing further guidance for the control rod assembly 120; and finally, the control rods of the control rod assembly 120 are inserted into the guide tube inside the fuel assembly 180, which is supported on the lower support plate 190. During the rod lowering process, the control rod assembly 120, consisting of the drive rod and the control rod, will sequentially pass through the upper guide tube 140, the lower guide tube 160, and the fuel assembly 180, ultimately reaching the predetermined position in the core, i.e., the guide tube. The entire structure forms a guide channel that runs from the top of the reactor to the core, and the deformation and relative motion of its various components directly affect the dropping behavior of the control rods.

[0032] Please see Figure 2 The drop rod control method includes the following steps: S10, acquiring the current state data of each control rod, and fusing the seismic acceleration with the corresponding drop rod acceleration in the current state data to obtain the fused state data of each control rod.

[0033] The control rod assembly 120 can include up to 24 control rods. The current state data of each control rod refers to the state data of that control rod at the start of the drop or at any point during the calculation process, including motion state data such as vertical displacement, drop velocity, drop acceleration, and displacement components in the lateral direction. The current state data also includes structural state data such as the overall cross-sectional bending stiffness, unit mass, and top area of ​​the motion assembly.

[0034] Specifically, vertical displacement refers to the cumulative distance the control rod travels downwards along the guide tube from its initial release position. Drop velocity refers to the instantaneous descent velocity of the control rod in the vertical direction. Drop acceleration refers to the instantaneous descent acceleration of the control rod in the vertical direction. The lateral displacement components refer to the offset of the control rod in the two horizontal axes perpendicular to the drop direction due to factors such as fluid disturbance or structural deformation.

[0035] The seismic acceleration was obtained based on the seismic safety analysis results of the reactor site. For the reactor control rod drive line structure, multiple excitation points were selected as input locations for the seismic load. These excitation points include the connection between the control rod guide tube and the pressure vessel top cover 130, the connection between the upper control rod guide tube 140 and the upper support plate 150, the connection between the lower control rod guide tube 160 and the core upper plate 170, and the connection between the fuel assembly 180 and the lower support plate 190. From the seismic safety analysis results, the seismic acceleration in three orthogonal directions at each of the above excitation points was extracted and denoted as follows: , , ,in, , , These are the vertical directions and two horizontal directions, which are mutually orthogonal. , , They are respectively in The vertical acceleration at any given moment and the seismic acceleration in both horizontal directions.

[0036] The seismic acceleration is fused with the corresponding drop bar acceleration in the current state data to obtain fused state data. The fusion process involves introducing the seismic load as an external excitation into the fluid motion equations of the control rod assembly. For components directly constrained to the external structure, i.e., the structural part corresponding to the location of the seismic load, the seismic impact is manifested as support excitation. Specifically, the extracted seismic acceleration at the corresponding location is used as the basic excitation input for that component in its motion equations. For control rod assemblies not directly connected to external constraints, the influence of the seismic load on these components is indirectly transmitted through fluid-structure interaction; therefore, the seismic acceleration needs to be fused with the corresponding drop bar acceleration in the current state data. The final fused state data is a comprehensive dataset integrating the control rod's own drop motion state and the effect of the seismic load.

[0037] Please see Figure 2 The drop bar control method also includes the following steps: S20, based on the fused state data, the lateral deformation displacement of each control bar caused by the seismic load is calculated using a preset fluid motion equation. The fluid motion equation is constructed by performing a fluid-structure interaction analysis on the control bars during the drop bar process, including non-viscous conservative fluid force, viscous non-conservative fluid resistance, pressure differential resistance, and fluid inertial force. The fluid motion equation includes fluid motion equations for lateral vibration and vertical drop.

[0038] The process of constructing the fluid motion equations involves treating the control rod assembly 120, which consists of the drive rod and the control rod, as an elastic unit and comprehensively considering the various fluid forces it experiences when falling in the fluid, thereby establishing a mathematical model that couples lateral vibration and vertical falling behavior.

[0039] First, a comprehensive fluid-structure interaction analysis of the control rod assembly during the drop process is required, and its initial fluid motion equations are constructed. The fluid forces considered in the analysis mainly include inviscid conservative fluid forces, viscous nonconservative fluid resistance, pressure drag, and fluid inertial forces. Inviscid conservative fluid forces originate from changes in fluid potential energy, are related to the drop velocity of the control rod assembly, and are energy-conserving; viscous nonconservative fluid resistance originates from viscous dissipation of the fluid; pressure drag is caused by uneven pressure distribution on the surface of the control rod assembly; and fluid inertial forces reflect the additional force required to accelerate the fluid surrounding the control rod assembly. Based on these mechanical principles and combined with elasticity theory, the motion equilibrium relationship of the control rod assembly in three-dimensional space is first established. This equilibrium relationship constitutes the initial fluid motion equations, including an initial vertical motion equation describing the downward motion along the drive line axis, and two initial lateral motion equations describing the lateral vibrations in two mutually perpendicular directions in the horizontal plane. These three equations, in their initial form, summarize the basic relationships between all the forces and motion components to be considered. The calculation formulas for the initial fluid motion equations are as follows:

[0040]

[0041]

[0042] in, The axial force at the top of the control rod assembly, which consists of the drive rod and the control rod. , All of these represent the vertical displacement of the control rod. , , These represent the viscous nonconservative fluid resistances acting on the control rod in the vertical direction and the two lateral directions, respectively. , These are the nonviscous conservative fluid forces acting in the two transverse directions of the control rod. , , These represent the displacement components of the control rod in the vertical direction and the two lateral directions, respectively. The time of the bat drop. , , These are the static pressure components acting on the control rod in the vertical direction and the two lateral directions, respectively. , These are the cross-sectional bending stiffnesses of the control rod assembly, which consists of the drive rod and the control rod, in two lateral directions. , These are the torques acting in the two lateral directions of the control rod assembly, which consists of the drive rod and the control rod.

[0043] Subsequently, the inviscid conservative fluid force needs to be applied to the two initial transverse motion equations. The inviscid conservative fluid dynamic pressure is the force source for the transverse vibration of the control rod assembly and the induction of fluid-structure interaction effects. When expanding the equations in the transverse direction, the specific expression of this fluid force needs to be substituted into the two initial transverse motion equations. The expansion process involves analyzing the bending deformation of the control rod assembly. Specifically, after discretizing the control rod assembly into multiple control rods, the transverse motion equation of each control rod needs to consider the elastic restoring force provided by its cross-sectional bending stiffness, the influence of the axial force inside the control rod (such as the force contributed by the top axial force and fluid pressure) on the transverse bending stability, and the effect of the inviscid conservative fluid dynamic pressure as an external excitation. After expansion and simplification, two transverse motion equations are finally obtained. These two transverse motion equations reveal how the fluid dynamic pressure is used as an excitation term and input into the bending vibration differential equation of the elastic system, which is the theoretical basis for analyzing the dynamic response of the control rod under transverse excitations such as earthquakes.

[0044] Next, the viscous nonconservative fluid resistance, pressure drag, and fluid inertial force need to be applied to the initial vertical motion equations. Vertical descent is the main motion form of the control rod process, and its dynamic behavior determines the descent time. When expanding the equations in the vertical direction, the specific physical models of the above three forces need to be substituted into the initial vertical motion equations. The direction of viscous nonconservative fluid resistance is opposite to the direction of motion and is one of the main resistances to descent. Pressure drag is formed by the pressure difference between the upper and lower end faces of the control rod assembly or before and after the structural protrusions. Fluid inertial force manifests as an added mass effect, that is, when the control rod assembly accelerates, it also needs to drive a part of the surrounding fluid to accelerate together, which is equivalent to increasing the effective mass of the control rod assembly. After substituting the mathematical expressions of these forces into the equations, the vertical motion equations of the control rod assembly are obtained. The vertical motion equation is a nonlinear differential equation, the core of which is to describe that the product of the mass of the control rod assembly (including the fluid added mass) and the vertical acceleration is equal to the algebraic sum of all vertical force components such as gravity, buoyancy, various fluid resistances, and internal axial forces.

[0045] Finally, the two lateral motion equations and the vertical motion equations are integrated to construct the complete fluid motion equations for the control rods. The fluid motion equations are a set of coupled partial differential equations. The coupling is mainly reflected in several aspects: First, the vertical velocity and acceleration of the falling rod affect the lateral motion equations through the fluid inertial force term; second, the amplitude and velocity of the lateral vibration change the flow field distribution, thus affecting the viscous drag and pressure drag acting vertically; subsequently, the interaction between multiple control rods analyzed by the coupling influence coefficient method connects all the lateral motion equations of the control rods through the fluid dynamic pressure term, forming a large coupled system. Therefore, the final constructed fluid motion equations are a mathematical model that comprehensively describes the control rods in three-dimensional space, simultaneously undergoing vertical falling and lateral vibration in two orthogonal directions, and fully considering various fluid forces and fluid-structure interaction effects. The calculation formulas for the fluid motion equations are as follows:

[0046] in, , All of these represent the vertical displacement of the control rod. , These are the flexural stiffness of the control rod sections in the two transverse directions, respectively. , , These represent the displacement components of the control rod in the vertical direction and the two lateral directions, respectively. The time of the bat drop. , , These represent the viscous nonconservative fluid resistances acting on the control rod in the vertical direction and the two lateral directions, respectively. , These are the nonviscous conservative fluid forces acting in the two transverse directions of the control rod. The unit mass of the control rod assembly, which consists of the drive rod and the control rod. It is the acceleration due to gravity. The pressure drag is caused by the fluid pressure gradient acting on the control rod. The fluid pressure borne at the top of the control rod assembly, which consists of the drive rod and the control rod. This refers to the top area of ​​the control rod assembly, which consists of the drive rod and the control rod. For the unit mass of the fluid, To control the acceleration of the falling rod, For fluid inertial force, The axial force at the top of the control rod assembly, which consists of the drive rod and the control rod. To control the distance between the bottom end of the control rod and the bottom end of the corresponding guide tube before the rod drops.

[0047] The formula for calculating the inviscid conservative fluid force is as follows:

[0048]

[0049] in, , The first The control rod has two lateral directions of nonviscous conservative fluid forces. For fluid density, The control rod number, The total number of control rods, , The first The, the The radius of each control rod, , , , All are the first The control stick to the first The coupling effect coefficient of each control rod The fluid velocity on the surface of the control rod in the vertical direction. , The first The control stick to the first The lateral deformation displacement of the control rod in two lateral directions.

[0050] When calculating the lateral deformation and displacement of each control rod in the control rod assembly due to seismic load, the fused state data must first be input into the fluid motion equations as initial and boundary conditions. The fused state data includes the vertical displacement, drop velocity, drop acceleration, lateral displacement components, and seismic acceleration of each control rod at the current time step.

[0051] Next, the transmission of seismic loads through fluid coupling to non-directly connected components needs to be considered. For moving components such as control rod assemblies, which are not directly mechanically constrained by the external seismic-resistant structure, the effect of seismic loads is reflected through the fluid motion equations. The vibration of the supporting structure (such as guide tubes) caused by the earthquake disturbs the internal coolant flow field, and this disturbance acts on the control rod surface in the form of fluid dynamic pressure. In the calculation, this process is manifested as: the seismic motion of the support points, as a boundary condition, affects the fluid dynamic pressure field. Ultimately, the non-viscous conservative fluid dynamic pressure acting on each control rod is the result of the combined action of all surrounding moving components (including the supporting structure that moves due to the earthquake).

[0052] Next, a specific numerical solution process is performed to obtain the lateral deformation displacement. The nonviscous conservative hydrodynamic pressure, calculated above and incorporating the seismic load, is treated as a known distributed load and substituted into the lateral motion equations of each control rod in the control rod assembly. The lateral motion equations are solved within a given time step. The solution process needs to consider the transient characteristics of the lateral motion equations, for example, by employing numerical integration methods such as the Newmark method or the central difference method to advance the calculation. Through solving, the displacement increments of each control rod in its vertical direction and both lateral directions at the end of the time step can be obtained.

[0053] Finally, the results are accumulated and output. By summing the displacement increments calculated at each time step and combining them with the initial positions, the lateral deformation displacement of each control rod due to seismic load can be obtained from the start of rod dropping to the current moment.

[0054] Please see Figure 2 The drop bar control method also includes the following steps: S30, calculate the frictional force generated by the collision between each control bar and the corresponding guide tube based on the lateral deformation displacement of each control bar, so as to obtain the total frictional force of all control bars.

[0055] S30 includes the following steps: S31. Based on the lateral deformation displacement of each control rod, the collision force generated between each control rod and its corresponding guide tube is calculated using a preset collision force model. The calculation formula for the collision force model is as follows:

[0056] in, For the first The collision force between each control rod and its corresponding guide tube This is the collision stiffness coefficient. This refers to the design clearance value between the control rod and the corresponding guide tube. For the first Lateral deformation displacement of each control rod.

[0057] The guide tube, acting as a constraint boundary for fixed or forced vibration, has a small annular design gap (design gap value) between it and the control rod. Under calm conditions, the control rod should fall to the center of this gap without contact. However, under seismic loads, the lateral deformation displacement of each control rod is calculated, describing the offset of the control rod's centerline relative to its original center position.

[0058] The criterion for determining whether a collision has occurred is whether, at any given moment, the magnitude of the lateral deformation displacement of the control rod exceeds the designed clearance value between the control rod and the corresponding guide tube. If it does, the control rod is considered to have made contact with the inner wall of the guide tube.

[0059] The pre-defined collision force model employs a contact mechanics method based on constructed reaction force functions, and its calculation formula reveals the relationship between the collision force and the lateral deformation displacement. In this formula, Representing the The impact force generated by a control rod at a specific contact point is a vector, with its direction along the normal direction from the center of the control rod to the contact point, and can be decomposed into two lateral directions. It is the collision stiffness coefficient, which comprehensively reflects the elastic modulus, Poisson's ratio, and local geometric curvature of the contact area of ​​the control rod shell and guide tube materials. Its value can be calibrated by Hertz contact theory or finite element contact analysis. It is the design gap value between the control rod and the corresponding guide tube, which is a known geometric design parameter.

[0060] The physical meaning of the collision force model is that the magnitude of the collision force is directly proportional to the lateral deformation displacement. When the lateral deformation displacement is less than or equal to the design gap value, the collision force is zero; when the lateral deformation displacement is greater than the design gap value, the collision force increases linearly with the increase of extrusion deformation. Using the collision force model, the collision force generated by each control bar at each time step during the bar dropping process can be calculated.

[0061] S30 further includes the following step: S32, based on the collision force between each control rod and its corresponding guide tube, the total friction force generated by the collision of all control rods is calculated using a preset Coulomb friction model. The calculation formula for the Coulomb friction model is as follows:

[0062] in, For the total friction force, For the first The coefficient of friction between each control rod and its corresponding guide tube.

[0063] The collision generates not only a normal collision force but also a tangential (i.e., along the control rod axis and the circumferential direction of the contact point) frictional force that hinders relative motion. A pre-defined Coulomb friction model is used to convert the normal collision force into tangential frictional resistance. In the Coulomb friction model, the total vertical frictional force generated by the collision of all control rods is the resistance term affecting the drop time. It is the first The coefficient of friction between a control rod and its corresponding guide tube is an empirical parameter. Its value depends on factors such as the material pairing of the contact surfaces (e.g., zirconium alloy to Inconel), surface roughness, presence of an oxide layer, and coolant environment. It is obtained through experimental measurement or by referring to engineering databases.

[0064] Coulomb's law of friction is based on the assumption that the maximum static friction and sliding friction are proportional to the normal force. During the drop phase, once the control rod and guide tube make contact, the vertical drop velocity and potential lateral relative velocity of the control rod are considered to be in a state of sliding friction. Therefore, at each point of contact, the magnitude of the tangential frictional resistance is equal to the normal impact force at that point multiplied by the coefficient of friction, and its direction is opposite to the direction of the relative velocity.

[0065] Since the primary direction of motion of the falling rods is vertical, the vertical component of the frictional resistance directly counteracts gravity and buoyancy, reducing the descent acceleration. By summing the frictional forces of all control rods at the current time, the total frictional force hindering the descent of the control rod assembly at the current time can be obtained. This total frictional force is a dynamic quantity that fluctuates with time, and its magnitude directly depends on the intensity and frequency of lateral collisions under seismic excitation, thus closely linking the randomness of seismic loads with the drag characteristics of the falling rod process.

[0066] Please see Figure 2 The drop bar control method also includes the following steps: S40, updating the fluid motion equation with the total friction force as a load term, calculating the drop bar parameters based on the updated fluid motion equation according to the fused state data, and controlling the control rod according to the drop bar parameters.

[0067] First, the vertical motion equations include load terms such as nonviscous conservative fluid forces, viscous nonconservative fluid drag, pressure drag, and fluid inertial forces. However, the total frictional force calculated is an additional drag generated by random collisions induced by the earthquake, and it is not explicitly included in the vertical motion equations. Therefore, this total frictional force needs to be added as a new load term to the force balance relationship of the vertical motion equations.

[0068] Specifically, the total frictional force is incorporated into the vertical motion equations as a means of hindering motion. This is equivalent to inputting the total frictional force as a known force into the vertical motion equations at the beginning of each time step, based on the predicted collision state from the previous or current time step. In this way, the lateral collision effect caused by the earthquake is completely transformed into a direct influence on vertical motion, achieving a complete two-way coupling between lateral vibration and vertical drop, rather than a simplified one-way estimation.

[0069] Next, based on the fused state data, calculations are performed using the updated fluid motion equations. The updated fluid motion equations, incorporating total friction, are then combined with the fused state data for a new solution. This solution process is a nonlinear transient dynamic numerical solution; for example, the finite element method can be used to spatially discretize the control rod assembly. In the time domain, time integration methods such as the central difference method or the Newmark method are employed. Within each time step, the solver needs to simultaneously solve the updated vertical and lateral motion equations. The vertical motion equations solve for the vertical acceleration, vertical velocity, and vertical displacement of the control rod; the lateral motion equations, under the current vertical motion state and seismic excitation, again solve for the lateral deformation and displacement of the control rod. Because the introduction of total friction changes the vertical acceleration, indirectly affecting fluid-structure interaction (e.g., changes in falling velocity alter fluid dynamic pressure) and potential collision states (since vertical motion and lateral vibration may be coupled), this is an iterative or implicit solution process.

[0070] Then, the drop rod parameters are calculated based on the solution results. These parameters are core indicators for evaluating the safety performance of the control rod under seismic conditions, and mainly include drop rod time, drop rod velocity, drop rod acceleration, drop rod displacement (i.e., the displacement of the control rod during the drop process), and the impact force of the control rod on the guide tube. Drop rod time refers to the total time from the issuance of the drop command (release of the control rod drive mechanism) to the complete insertion of the control rod into the guide tube. The drop rod time is determined by accumulating each time step until the vertical displacement of the top of the control rod reaches the preset drop stroke. Drop rod velocity and acceleration are curves directly output during the solution process, reflecting the dynamic characteristics of the entire drop process, and are used to analyze whether abnormal deceleration or jamming occurs during the process. The impact force of the control rod on the guide tube is calculated using a preset impact calculation model at the instant the bottom of the control rod contacts the bottom of the guide tube; the magnitude of the impact force directly affects the structural integrity of the fuel assembly. All these parameters together constitute a quantitative basis for judging whether the drop rod behavior under seismic conditions meets safety requirements.

[0071] Finally, the control rods are controlled based on the calculated drop parameters. Here, "control" does not refer to real-time operation, but rather to safety assessment and design optimization based on simulation results, providing a basis for actual engineering control. Specifically, the calculated drop time is compared with the maximum permissible drop time required by nuclear safety regulations and design specifications. If the calculated drop time is less than the permissible value and the impact force is within acceptable limits, it indicates that the control rod drive line performance is safe under seismic loads and design parameters, and the reactor can be reliably shut down. If the calculated drop time is close to or exceeds the permissible value, it indicates a risk of drop delay. In this case, the cause needs to be analyzed: it may be due to excessively strong seismic loads leading to excessive collision friction, or it may be due to insufficient design clearances or excessively high friction coefficients. Based on this analysis, feedback can guide design optimization, such as adjusting the guide tube clearance design, selecting materials with lower friction coefficients for pairing, or optimizing the release characteristics of the control rod drive mechanism. Furthermore, the calculated maximum impact force can be used to verify the strength of the guide tubes.

[0072] The drop bar control method also includes the following steps: determining whether the control bar collides with the bottom end of the corresponding guide tube, and, upon collision, calculating the drop bar impact force based on the drop bar velocity and the vertical displacement of the control bar after the collision with the corresponding guide tube, using a preset impact calculation model. The formula for calculating the drop bar impact force is as follows:

[0073] in, For the first The impact force of the control rod falling. , The first Stiffness and damping of each control rod and its corresponding guide tube during impact. , The first The vertical displacement and drop speed of each control rod.

[0074] First, it is necessary to continuously monitor whether the control rod collides with the bottom of the corresponding guide tube. This assessment is performed simultaneously during the calculation of the drop parameters. As the control rod continues to fall, the vertical position of its bottom (or lower end structure) in space constantly changes. The bottom of the guide tube is a fixed mechanical limiting structure. By monitoring the calculated vertical displacement of the control rod's bottom in real time, it is possible to accurately determine whether a collision has occurred. A collision is considered to have occurred when the vertical displacement of the control rod exceeds the distance between the bottom of the control rod and the bottom of the guide tube before the drop.

[0075] When a collision is detected, the impact force of the control rod must be calculated immediately using a pre-defined impact calculation model based on the drop rod velocity and the vertical displacement of the control rod after the collision with the corresponding guide tube, as specified in the drop rod parameters. The drop rod parameters specifically refer to the transient data on the control rod's motion state obtained through calculation at the instant before the collision, including the drop rod velocity and the vertical displacement of the control rod. The drop rod velocity is the instantaneous vertical velocity of the bottom end of the control rod at the moment before the collision, determining the initial kinetic energy of the impact. The vertical displacement of the control rod after the collision with the corresponding guide tube describes the further intrusion displacement of the bottom end of the control rod relative to the bottom end of the guide tube after the collision. This is a dynamically changing quantity that increases from zero at the instant of the collision, reflecting the local compressive deformation process of the structure.

[0076] The pre-defined impact calculation model employs a spring-damper-based physical model to simulate the transient mechanical behavior of a collision. In the calculation formulas of the impact calculation model, For the first The impact force of the control rod falling is a dynamic force that varies over time. , The first The equivalent impact stiffness and equivalent impact damping of the control rod and its corresponding guide tube in the impact contact area. Impact stiffness reflects the overall equivalent compressive stiffness of the lower end structure of the control rod and the bottom support structure of the guide tube in the contact area, and is determined by the material properties (such as elastic modulus) and geometry (such as contact area and support structure form) of both parts. Impact damping is used to simulate energy dissipation during a collision, such as kinetic energy loss caused by internal material friction and localized plastic deformation. , That is, after the collision occurs, the first The vertical displacement (i.e., intrusion displacement) and vertical velocity at the bottom of each control rod are considered. The physical meaning of the impact calculation model lies in the fact that the impact force consists of two parts: one part is the restoring force generated by the elastic deformation of the structure, whose magnitude is proportional to the intrusion displacement, and the proportionality coefficient is the impact stiffness; the other part is the dissipative force generated by the damping effect, whose magnitude is proportional to the relative velocity of the collision, and the proportionality coefficient is the impact damping. Therefore, the impact force varies dynamically with the intrusion depth and intrusion velocity, rapidly reaching its peak in the initial stage of the collision, and then potentially oscillating and decaying due to rebound.

[0077] The impact calculation model can be used to calculate the first... The complete time-history curves of the impact force versus time during the collision of each control rod with the bottom of the guide tube are recorded. The peak impact force is used to assess whether the stress levels of structures such as fuel assembly mounts and lower guide tube supports exceed allowable limits. The calculated impact force can also be used as input load for subsequent structural dynamics analysis to assess the vibration response and fatigue damage of local structures. Performing this calculation separately for all control rods yields the impact load distribution of the entire control rod assembly on the bottom structure of the reactor core, providing a quantitative basis for a comprehensive assessment of the safety of shutdown impacts.

[0078] As can be seen, the above scheme, by directly integrating seismic loads into the control rod state and driving dynamic calculations, can accurately simulate the random collision process between the control rod and the guide tube under seismic conditions. Based on the fused state data, the lateral deformation displacement is calculated through a preset fluid motion equation, and then the frictional force generated by random collisions is solved. This total frictional force is then fed back to update the fluid motion equation, achieving precise quantification of the complex frictional resistance caused by the earthquake during the rod drop process. The calculated rod drop parameters, such as drop time and velocity, more realistically reflect the actual rod drop behavior under seismic conditions. This significantly improves the accuracy of rod drop parameter prediction and its applicability to real-world conditions, providing a technical basis for assessing the control rod's state and ensuring safety under extreme loads such as earthquakes, based on more reliable rod drop parameters, effectively mitigating the safety risks inherent in existing technologies that neglect random collision effects.

[0079] Please see Figure 3The present invention also provides a control rod drop control device, which can apply the above-described drop control method. The drop control device includes a data fusion module 210, a displacement calculation module 220, a friction calculation module 230, and a drop control module 240. The data fusion module 210 acquires the current state data of all control rods and merges the seismic acceleration with the corresponding drop acceleration in the current state data to obtain fused state data. The displacement calculation module 220 calculates the lateral deformation displacement of each control rod due to seismic load based on the fused state data and a preset fluid motion equation. The friction calculation module 230 calculates the friction force generated by the collision between each control rod and the corresponding guide tube based on the lateral deformation displacement of each control rod to obtain the total friction force of all control rods. The drop control module 240 updates the fluid motion equation with the total friction force as a load term, calculates the drop parameters based on the updated fluid motion equation using the fused state data, and controls the control rods according to the drop parameters.

[0080] Specific limitations regarding the drop bar control device can be found in the limitations of the drop bar control method described above, and will not be repeated here. Each module in the aforementioned drop bar control device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in hardware or independently of the memory in the electronic device, or stored in software form in the memory of the electronic device, so that the memory can call and execute the operations corresponding to each module.

[0081] Please see Figure 4 The electronic device 300 may include a memory 310, a processor 320, and a bus, and may also include a computer program stored in the memory 310 and executable on the processor 320, such as a program for a method of controlling the drop of a control rod.

[0082] The memory 310 includes at least one type of readable storage medium, including flash memory, portable hard drive, multimedia card, card-type memory (e.g., SD or DX memory), magnetic memory, magnetic disk, optical disk, etc. In some embodiments, the memory 310 can be an internal storage unit of the electronic device 300, such as the portable hard drive of the electronic device 300. In other embodiments, the memory 310 can also be an external storage unit of the electronic device 300, such as a plug-in portable hard drive, smart media card (SMC), secure digital (SD) card, flash card, etc., equipped on the electronic device 300. Furthermore, the memory 310 can include both internal and external storage units of the electronic device 300. The memory 310 can be used not only to store application software and various types of data installed on the electronic device 300, such as the code for the control stick's drop control method, but also to temporarily store data that has been output or will be output.

[0083] In some embodiments, the processor 320 may be composed of integrated circuits, such as a single packaged integrated circuit or multiple integrated circuits packaged with the same or different functions, including combinations of one or more central processing units (CPUs), microprocessors, digital processing chips, graphics processors, and various control chips. The processor 320 is the control unit of the electronic device 300, connecting various components of the electronic device 300 via various interfaces and lines. It executes programs or modules stored in the memory 310 (such as programs for controlling the drop of a control stick) and calls data stored in the memory 310 to perform various functions and process data of the electronic device 300.

[0084] The processor 320 executes the operating system of the electronic device 300 and various installed application programs. The processor 320 executes the application programs to implement the steps in the above-described control rod lowering control method.

[0085] A computer program can be divided into one or more modules. One or more modules are stored in memory 310 and executed by processor 320 to complete this application. The one or more modules can be a series of computer program instruction segments capable of performing specific functions, which describe the execution process of the computer program in electronic device 300. For example, the computer program can be divided into a data fusion module 210, a displacement calculation module 220, a friction calculation module 230, a drop bar control module 240, etc.

[0086] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for controlling the dropping of a control rod, characterized in that, include: The current state data of each control rod is obtained, and the seismic acceleration is fused with the corresponding falling rod acceleration in the current state data to obtain the fused state data of each control rod. Based on the fusion state data, the lateral deformation displacement of each control rod due to seismic load is calculated using a preset fluid motion equation. Based on the lateral deformation displacement of each control rod, calculate the frictional force generated by the collision between each control rod and the corresponding guide tube to obtain the total frictional force of all control rods. The total friction force is used as a load term to update the fluid motion equation. Based on the fusion state data, the drop bar parameters are calculated using the updated fluid motion equation, and the control rod is controlled according to the drop bar parameters.

2. The method for controlling the drop of the control rod according to claim 1, characterized in that, The fluid motion equations are constructed by performing fluid-structure interaction analysis on the control rod during the drop process, including nonviscous conservative fluid forces, viscous nonconservative fluid resistance, pressure differential resistance, and fluid inertial forces. The fluid motion equations include fluid motion equations for lateral vibration and vertical drop.

3. The method for controlling the drop of the control rod according to claim 2, characterized in that, The formula for calculating the fluid motion equation is as follows: in, , All of these represent the vertical displacement of the control rod. , These are the cross-sectional bending stiffnesses of the control rod assembly, which consists of the drive rod and the control rod, in two lateral directions. , , These represent the displacement components of the control rod in the vertical direction and the two lateral directions, respectively. The time of the bat drop. , , These represent the viscous nonconservative fluid resistances acting on the control rod in the vertical direction and the two lateral directions, respectively. , These are the nonviscous conservative fluid forces acting in the two transverse directions of the control rod. The unit mass of the control rod assembly, which consists of the drive rod and the control rod. It is the acceleration due to gravity. The pressure drag is caused by the fluid pressure gradient acting on the control rod. The fluid pressure borne at the top of the control rod assembly, which consists of the drive rod and the control rod. This refers to the top area of ​​the control rod assembly, which consists of the drive rod and the control rod. For the unit mass of the fluid, To control the acceleration of the falling rod, For fluid inertial force, The axial force at the top of the control rod assembly, which consists of the drive rod and the control rod. To control the distance between the bottom end of the control rod and the bottom end of the corresponding guide tube before the rod drops.

4. The method for controlling the drop of the control rod according to claim 2 or 3, characterized in that, The formula for calculating the inviscid conservative fluid force is as follows: in, , The first The control rod has two lateral directions of nonviscous conservative fluid forces. For fluid density, The control rod number, The total number of control rods, , The first The, the The radius of each control rod, , , , All are the first The control stick to the first The coupling effect coefficient of each control rod The fluid velocity on the surface of the control rod in the vertical direction. , The first The control stick to the first The lateral deformation displacement of the control rod in two lateral directions.

5. The method for controlling the drop of the control rod according to claim 1, characterized in that, The frictional force generated by the collision between each control rod and its corresponding guide tube is calculated based on the lateral deformation displacement of each control rod to obtain the total frictional force of all control rods, including: Based on the lateral deformation displacement of each control rod, the collision force generated between each control rod and the corresponding guide tube due to the collision is calculated using a preset collision force model. Based on the collision force between each control rod and its corresponding guide tube, the total friction force generated by the collision of all control rods is calculated using a preset Coulomb friction model.

6. The method for controlling the drop of the control rod according to claim 5, characterized in that, The calculation formula for the collision force model is as follows: in, For the first The collision force between each control rod and its corresponding guide tube The collision stiffness coefficient is... This refers to the design clearance value between the control rod and the corresponding guide tube. For the first Lateral deformation displacement of each control rod.

7. The method for controlling the drop of the control rod according to claim 5, characterized in that, The calculation formula for the Coulomb friction model is as follows: in, For the total friction force, For the first The coefficient of friction between each control rod and its corresponding guide tube.

8. The method for controlling the drop of a control rod according to claim 1, characterized in that, The drop bar control method further includes: determining whether the control bar collides with the bottom end of the corresponding guide tube, and when colliding, calculating the drop bar impact force of the control bar based on the drop bar speed in the drop bar parameters and the vertical displacement of the control bar after colliding with the corresponding guide tube, through a preset impact calculation model.

9. The method for controlling the drop of a control rod according to claim 8, characterized in that, The formula for calculating the impact force of the falling rod is as follows: in, For the first The impact force of the control rod falling. , The first Stiffness and damping of each control rod and its corresponding guide tube during impact. , The first The vertical displacement and drop speed of each control rod.

10. A control device for controlling the dropping of a control rod, characterized in that, include: The data fusion module is used to acquire the current state data of each control rod and fuse the seismic acceleration with the corresponding drop rod acceleration in the current state data to obtain the fused state data of each control rod. The displacement calculation module is used to calculate the lateral deformation displacement of each control rod due to seismic load based on the fused state data and a preset fluid motion equation. The friction calculation module is used to calculate the friction force generated between each control rod and the corresponding guide tube due to collision based on the lateral deformation displacement of each control rod, so as to obtain the total friction force of all control rods. The drop bar control module is used to update the fluid motion equation with the total friction force as a load term, calculate the drop bar parameters based on the updated fluid motion equation according to the fusion state data, and control the control bar according to the drop bar parameters.

11. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the control rod dropping control method as described in any one of claims 1 to 9.

12. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the control rod dropping control method as described in any one of claims 1 to 9.

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