A method and device for releasing thermal stress of a support structure suitable for a high temperature gas cooled reactor

Abstract

The application relates to the technical field of nuclear power engineering, and discloses a support structure thermal stress release method and device suitable for a high-temperature gas cooled reactor, which comprises the following steps: a door-shaped frame is constructed; positioning anchor plates and thermal stress release anchor plates are arranged at the bottom supports of two vertical columns respectively; the former is provided with a round hole to form a fixed support; the latter is provided with an oblong hole to form a one-way sliding support; the long axis direction of the oblong hole is parallel to the axis of the cross beam; the length of the oblong hole is set based on the theoretical thermal expansion amount and a safety coefficient; the structural strength checking including a bending moment reduction coefficient and multi-dimensional coupling conditions is performed; and a thermal expansion sliding stroke is reserved in the oblong hole during installation. According to the application, the structural thermal deformation is converted into relative displacement along the long hole direction through an asymmetric constraint system, the accumulated temperature difference stress in the interior is effectively eliminated, the horizontal thrust of the support on the foundation is reduced, and the stability of the structure under lateral load is considered.

Description

Technical Field

[0001] This invention relates to the field of nuclear power engineering technology, specifically to a method and apparatus for relieving thermal stress in the support structure of a high-temperature gas-cooled reactor. Background Technology

[0002] The process piping systems of high-temperature gas-cooled reactor nuclear power plants operate under high-temperature conditions for extended periods, resulting in significant thermal expansion and deformation of the pipes and their supporting structures. In engineering practice, to accommodate the support requirements of large-diameter pipes, a portal steel frame structure consisting of two columns and one beam is often used as the primary support method.

[0003] In traditional support structure design and installation processes, to ensure the structural stability under earthquakes and wind loads, the bottoms of the columns on both sides of the portal frame are typically rigidly connected to the concrete foundation using anchor bolts and standard circular holes. However, this double-ended fixed connection method restricts the steel structure's ability to deform freely in the horizontal direction. When the support beams undergo axial elongation due to conducted high temperatures, the columns on both sides are forced to undergo forced displacement and bending because their bottoms are constrained to a fixed position, resulting in the accumulation of significant thermal stress within the structure.

[0004] This thermal stress ultimately manifests as a massive horizontal thrust on the concrete foundation from the base of the support structure. In the civil engineering design of nuclear power plant buildings, embedded parts and concrete foundations typically have high load-bearing redundancy for vertical gravity loads, but relatively weak capacity to withstand horizontal shear forces. Excessive horizontal thrust can easily cause anchor bolts to bear shear stresses exceeding allowable values, and may even lead to deformation of embedded anchor plates or cracking of the concrete foundation, seriously threatening the structural integrity of the support structure and the operational safety of the piping system. Furthermore, existing design codes mostly focus on the calculation of static gravity loads, lacking effective structures for releasing secondary stresses caused by thermal expansion obstruction, and also lacking suitable strength verification methods under asymmetric boundary conditions. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method and apparatus for releasing thermal stress in the support structure of a high-temperature gas-cooled reactor. This solves the problem that existing portal supports for high-temperature gas-cooled reactors, due to rigid fixation at both ends restricting the thermal expansion of the crossbeams, result in the accumulation of huge thermal stress within the structure, which in turn generates destructive horizontal thrust on the foundation. Furthermore, there is a lack of effective thermal stress release structures and corresponding strength verification methods.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for relieving thermal stress in a support structure suitable for high-temperature gas-cooled reactors, comprising the following steps: S1. Construct a support structure with asymmetric constraint characteristics: Connect two vertical steel structures vertically to the two ends of a horizontal steel structure to form a portal frame. Fix a positioning anchor plate to the bottom of one of the vertical steel structures and fix a thermal stress relief anchor plate to the bottom of the other vertical steel structure. S2. Set the geometric parameters of the anchoring components: Open a circular through hole on the positioning anchoring plate to form a fixed support, and open an elongated hole on the thermal stress relief anchoring plate to form a one-way sliding support. The long axis of the elongated hole is parallel to the axial direction of the transverse steel structure. S3. Perform structural strength verification: Based on the pipeline load and structural parameters, perform multi-dimensional stress verification on the support structure to verify whether the structural stress meets the elastic design requirements. S4. Implement thermal displacement compensation for piping installation and operation: The positioning anchor plate is fastened to the foundation with fasteners as a fixed reference, and the thermal stress relief anchor plate is movably connected to the foundation with fasteners. Under hot operation, the thermal stress is released by the relative displacement generated by the thermal stress relief anchor plate along the long axis of the elongated hole.

[0007] Preferably, in the step of setting the geometric parameters of the anchoring assembly, the total length of the elongated hole along the major axis is configured to include at least two parts: the first part is the nominal diameter of the fastener and the second part is the thermal displacement compensation amount. The logic for determining the thermal displacement compensation amount is as follows: obtain the linear expansion coefficient of the transverse steel structure, the span distance between the center lines of the two vertical steel structures, and the design temperature difference; define the product of the three as the theoretical thermal expansion amount; and multiply the theoretical thermal expansion amount by a safety factor greater than 1 to obtain the thermal displacement compensation amount.

[0008] Preferably, in the step of setting the geometric parameters of the anchoring assembly, the width of the elongated hole in the direction perpendicular to the long axis is set to be consistent with the diameter of the circular through hole on the positioning anchoring plate, and the width dimension has a clearance fit with the diameter of the connecting fastener to limit the lateral displacement of the vertical steel structure in the direction perpendicular to the axis of the transverse steel structure.

[0009] Preferably, the step of performing structural strength verification includes a first verification condition and a second verification condition; The first verification condition includes verifying that the average shear or bending stress caused by horizontal loads must not exceed 60% of the material's yield strength; The second verification condition includes verifying that the sum of the compressive stress caused by the vertical load and the stress caused by 30% of the horizontal load must not exceed 40% of the material's yield strength.

[0010] Preferably, the step of performing structural strength verification further includes a third verification condition and a fourth verification condition; The third verification condition includes verifying that the bending stress calculated based on the horizontal load and the effective height of the vertical steel structure, after being corrected by introducing a moment reduction factor of 0.15 based on the stiffness distribution characteristics of the portal frame, must not exceed 60% of the material's yield strength. The fourth verification condition includes verifying that the sum of the normalized axial stress term and the normalized bending stress term does not exceed 1.0.

[0011] Preferably, the step of performing structural strength verification further includes: If any of the first to fourth verification conditions is not met, then the process returns to adjusting the geometric parameters of the elongated hole or adjusting the cross-sectional dimensions of the vertical and horizontal steel structures until all verification conditions are met simultaneously.

[0012] Preferably, the safety factor is set to a value range of 1.2 to 1.5 to cover construction and installation errors, deformation in non-uniform temperature fields, and displacement margin under seismic conditions.

[0013] Preferably, in the step of implementing thermal displacement compensation for pipe system installation and operation, under normal temperature installation conditions, the fastener rod at the thermal stress relief anchor plate is positioned at a preset initial position within the elongated hole. This preset initial position has a free stroke greater than the theoretical thermal expansion in the direction away from the positioning anchor plate.

[0014] A thermal stress relief device for a support structure suitable for high-temperature gas-cooled reactors, comprising: The main frame of the portal frame consists of two vertical steel structures and a horizontal steel structure connecting the tops of the two vertical steel structures. A positioning anchor plate is fixedly connected to the bottom of one of the vertical steel structures, and the positioning anchor plate has a circular through hole for forming a fixed support; A thermal stress relief anchor plate is fixedly connected to the bottom of another vertical steel structure, and the thermal stress relief anchor plate has an elongated hole for forming a one-way sliding support. The long axis of the oblong hole is parallel to the axial direction of the transverse steel structure, and the length of the oblong hole is greater than the sum of the theoretical thermal expansion of the transverse steel structure under the design temperature difference and the diameter of the fastener.

[0015] Preferably, the width of the elongated hole in the direction perpendicular to the long axis forms a clearance fit with the diameter of the connecting fastener, and the tolerance range of this clearance fit is 0.5 mm to 1.0 mm, so as to limit the lateral displacement of the thermal stress relief device of the bracket structure.

[0016] Working principle: During bracket installation, the fixed end anchor plate is rigidly locked to the foundation through a circular hole as a zero displacement reference, and the floating end anchor plate is connected to the anchor bolt through an elongated hole with a reserved free stroke. When the high-temperature gas-cooled reactor operates, causing the transverse steel structure to elongate due to heat, the rigid constraint of the positioning end forces the thermal expansion deformation to drive the vertical steel structure of the floating end to displace outward along the long axis of the elongated hole. The fasteners generate controlled relative sliding within the elongated hole, thereby converting the internal thermal stress accumulated due to deformation obstruction in the traditional double-end fixed structure into macroscopic displacement for unloading, avoiding destructive horizontal thrust to the foundation.

[0017] This invention provides a method and apparatus for relieving thermal stress in the support structure of a high-temperature gas-cooled reactor. It has the following beneficial effects: 1. This invention constructs an asymmetric constraint system with one end fixed and the other end mobile, utilizing the elongated holes on the thermal stress relief anchor plate to provide unidirectional degrees of freedom. This transforms the thermal expansion deformation of the transverse steel structure under high-temperature conditions into controllable displacement along a specific direction. This design fundamentally changes the force-bearing mode of traditional double-ended fixed supports, effectively eliminating the huge thermal stress accumulated inside the structure due to the obstruction of thermal expansion, and significantly reducing the horizontal thrust of the support root on the concrete foundation. This avoids the risk of foundation cracking or anchor failure, ensuring the safe operation of the high-temperature gas-cooled reactor piping system.

[0018] 2. This invention establishes an improved strength verification method for asymmetric thermal compensation supports. Based on the ASME code, it introduces a moment reduction factor and multi-dimensional coupling verification conditions. This method fully considers the superposition effect of vertical load and horizontal guiding load under asymmetric boundary conditions. By setting more stringent combined stress limit conditions, it ensures that the support is always within the elastic working range under complex stress conditions, thus solving the problem that conventional verification methods are difficult to accurately assess the safety of such irregularly constrained structures.

[0019] 3. This invention achieves a balance between structural stability and thermal compensation capability by accurately calculating the geometric parameters of the anchoring components and combining them with specific installation techniques. By setting the width of the elongated hole to form a small gap fit with the fastener, the thermal freedom along the pipe axis is released while the lateral displacement of the support in the direction perpendicular to the pipe axis is strictly limited, effectively preventing structural instability under wind load or earthquake conditions. At the same time, the length of the elongated hole and the preset initial position during installation, based on the theoretical thermal expansion and safety factor, eliminate the risk of rigid interference between the fastener and the hole wall under hot conditions. Attached Figure Description

[0020] Figure 1 This is a perspective view of the present invention; Figure 2This is a schematic diagram of the positioning anchor plate structure of the present invention; Figure 3 This is a schematic diagram of the thermal stress relief anchor plate structure of the present invention; Figure 4 This is a flowchart of the thermal stress relief method for the support structure of the present invention.

[0021] The components include: 1. Vertical steel structure; 2. Horizontal steel structure; 3. Positioning anchor plate; 4. Thermal stress relief anchor plate. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example: Please see the appendix Figure 1 - Appendix Figure 4 This invention provides a method for relieving thermal stress on a support structure suitable for high-temperature gas-cooled reactors, comprising the following steps: S1. Construct an asymmetric constrained support structure, assemble the vertical steel structure 1 and the horizontal steel structure into a portal frame body through welding process, and respectively configure the positioning anchor plate 3 and the thermal stress release anchor plate 4 at the bottom support of the frame. S2. Calculate and set the geometric parameters of the anchoring components. Based on the design temperature of the pipeline system and the coefficient of thermal expansion of the material, determine the hole diameter fit tolerance of the positioning anchor plate 3, as well as the axial length and width of the rectangular hole in the thermal stress relief anchor plate 4. S3. Perform structural strength verification based on ASME code improvement, obtain the vertical and horizontal load data of the support structure, substitute them into the preset verification model containing four sets of inequality constraints for calculation, and verify whether the stress level of the structural components meets the safety design requirements. S4. Implement thermal displacement compensation for pipe system installation and operation. The pipe system is constrained to the steel structure 2 by pipe clamps. The connection position of the positioning anchor plate 3 is locked at normal temperature. Under high temperature operation conditions, the connector is allowed to generate controlled displacement in the rectangular hole of the thermal stress release anchor plate 4 along the preset direction.

[0024] The specific implementation method for constructing an asymmetrically constrained support structure is as follows: This step aims to establish a solid structure capable of bearing pipe loads and possessing adaptive thermal deformation capabilities. The process mainly includes the following sub-steps: Assemble the main body of the rigid portal frame. High-temperature resistant structural steel meeting the requirements of high-temperature gas-cooled reactor operation is selected, and vertical steel structure 1 and horizontal steel structure 2 are fabricated separately. The two vertical steel structures 1 are vertically welded to both ends of the horizontal steel structure 2, forming an inverted U-shaped portal frame. This type of portal frame serves as the main load-bearing unit, supporting and constraining the high-temperature pipelines through pipe clamps installed on the crossbeams. The specific selection of pipe clamps, their connection structure with the steel structure, and welding process specifications all follow relevant nuclear power construction standards or steel structure design specifications, and will not be elaborated further here.

[0025] Differentiated bottom anchoring components are configured. Anchor plates with different constraint characteristics are installed at the two bottom supports of the portal frame to create asymmetric mechanical boundary conditions. Positioning anchor plates 3 and thermal stress relief anchor plates 4 are welded to the bottom of the two vertical steel structures 1, respectively. The connections between the anchor plates and the bottom of the columns are all full-penetration welds to ensure that the connection strength is not less than the strength of the base material, thus ensuring the integrity of load transfer.

[0026] Construct a fixed reference end. The aforementioned positioning anchor plate 3 has multiple pre-drilled circular through holes. The geometric center of the circular through holes is the positioning reference point of the bracket on the installation plane. In terms of structural function, the circular through holes, together with fasteners, form a fixed hinge support or a rigid fixed end, restricting the translational degrees of freedom of the side column in the X and Y directions in the horizontal plane. This anchors the entire bracket system at the preset coordinate position of the concrete foundation, preventing the device from undergoing overall displacement under non-thermal deformation conditions such as earthquakes or equipment vibrations.

[0027] Constructing a thermal stress relief end. The aforementioned thermal stress relief anchor plate 4 has multiple pre-fabricated elongated holes. These holes have a clear directional characteristic; their major axis is parallel to the axis of the transverse steel structure, which is the main expansion direction of the support structure after heating. Functionally, these elongated holes, in conjunction with fasteners, form a unidirectional sliding constraint, restricting the displacement of the side column in the vertical direction and perpendicular to the beam axis, while releasing the translational degree of freedom along the beam axis.

[0028] Through the above steps, a structural system with one end fixed and the other end floating is formed. When the ambient temperature or pipe temperature rises and causes the beam to thermally expand, due to the limitation of the fixed reference end, the thermal deformation will drive the transverse steel structure 2 to release the thermal stress. The anchor plate 4 will produce controlled horizontal sliding relative to the fasteners on the foundation. This structural design transforms the huge internal stress generated by the thermal expansion resistance in the traditional double-end fixed bracket into the free displacement of the anchor plate in the elongated hole, thereby realizing the unloading of thermal stress at the structural level.

[0029] The specific implementation method for calculating and setting the geometric parameters of the anchoring assembly is as follows: This step aims to establish the tolerance boundary of the support system for thermal displacement. By combining physical installation dimensions with thermodynamic deformation laws, the key geometric characteristics of various anchor plates are determined. This process mainly includes the following sub-steps: Determine the fitting accuracy of the positioning anchor plate. For the positioning anchor plate 3, the bolt holes are prefabricated as circular holes. In order to establish the fixed reference of the system, the radial fitting clearance between the circular hole and the fastener needs to be controlled. This fitting clearance is controlled within a small range to form a tight fit. The core of this design is to eliminate the ineffective clearance between the connecting pairs and ensure that after the bolts are tightened, the anchor plate forms a rigid positioning node relative to the concrete foundation, thereby ensuring the verticality of the support column and the accuracy of the initial installation position.

[0030] Define the direction of freedom for thermal stress release. For the thermal stress release anchor plate 4, the bolt holes on it are designed as directional elongated holes. In order to ensure the lateral stability of the support, the diameter of the elongated hole in the width direction is set to be consistent with the diameter logic of the aforementioned positioning circular hole, that is, to form a small clearance fit with the diameter of the fastener, thereby limiting the displacement of the support under lateral wind load or seismic load. At the same time, the long axis direction of the elongated hole is precisely aligned with the expected thermal expansion extension direction of the steel structure beam, thereby establishing a unidirectional degree of freedom release channel.

[0031] A calculation model for the length of an elongated hole based on thermal deformation is constructed. The total length of the elongated hole along its major axis is determined not only by the physical dimensions of the fastener, but also by the sum of the space occupied by the fastener and the space for thermal displacement compensation.

[0032] The total length of the oblong hole is configured to include at least the sum of the following two parts: The first part is the nominal diameter of the connecting fastener; The second part is the thermal displacement compensation amount.

[0033] The determination of thermal displacement compensation follows this logic: First, obtain the linear expansion coefficient of the steel structure material, the span distance between the center lines of the columns at both ends of the support, and the difference between the design maximum operating temperature and the installation environment temperature. The product of these three is defined as the theoretical thermal expansion. Second, to avoid the risks of construction errors, non-uniform temperature field distribution, and displacement superposition under seismic conditions, a safety redundancy coefficient greater than 1 is introduced. Finally, the theoretical thermal expansion is multiplied by the safety redundancy coefficient to obtain the final thermal displacement compensation.

[0034] By setting the elongated hole length using the above logic, it is ensured that the fastener remains within the effective stroke range of the elongated hole throughout the entire life cycle of the device, avoiding rigid interference between the fastener shank and the hole wall end, thereby preventing secondary shear stress caused by thermal expansion obstruction.

[0035] The specific implementation method for performing structural strength verification based on ASME code improvements is as follows: This step aims to establish a safety evaluation system applicable to the asymmetric thermal compensation support of high-temperature gas-cooled reactors. Considering that the support not only bears conventional gravity loads during operation but also horizontal thrust generated by thermal expansion, conventional single-stress verification methods are insufficient to comprehensively cover its failure modes. Therefore, this embodiment adopts a multi-dimensional coupled verification logic, specifically including the following sub-steps: Obtain structural design parameters and load data. Extract key physical quantities from the pipeline stress analysis report and support structure design drawings. Among these, structural geometric and material parameters include: the effective cross-sectional area of ​​the support column, denoted as... The bending modulus of the support column is denoted as The effective height of the support column is recorded as follows: This usually refers to the vertical distance from the anchor point to the centerline of the beam and the yield strength of the structural steel at the design temperature, denoted as... The operating load parameters include: the vertical load borne by the support, denoted as... The force corresponding to the first main axis direction and the horizontal guiding load borne by the support are denoted as... This corresponds to the force in the direction of the second principal axis.

[0036] Perform independent and coupled verification of shear and axial stress. For stress concentration that may occur under special boundary conditions where the support is fixed at one end and moves at the other end, construct the first verification condition and the second verification condition.

[0037] The first verification condition limits the average stress dominated by shear or bending caused by horizontal loads, requiring that the stress value caused by horizontal loads not exceed 60% of the material's yield strength. Its mathematical expression is: ; The second verification condition is used to limit the combined axial stress under bidirectional load coupling. Considering the superposition effect of vertical and horizontal loads, the sum of the vertical stress and 30% of the horizontal stress must not exceed 40% of the material's yield strength. This setting is more conservative than conventional specifications to meet the high safety requirements of nuclear-grade equipment. Its mathematical expression is: ; Perform verification of bending stress and its interaction with axial force. For the bending behavior of the cantilever end or frame column of the portal frame under horizontal thrust, construct the third and fourth verification conditions.

[0038] The third verification condition focuses on the bending moment effect generated by horizontal forces. This takes into account the support height. To mitigate the amplification effect of bending moment, a bending moment reduction factor of 0.15 is introduced, requiring that the calculated bending stress value not exceed 60% of the material's yield strength. Its mathematical expression is: ; The fourth verification condition is the comprehensive interaction ratio verification. This condition is used to assess the nonlinear coupling risk between axial compression / tension and bending deformation, requiring that the sum of the normalized axial stress term and the bending stress term does not exceed 1.0, i.e., the structure must be within the elastic limit state envelope. Its mathematical expression is: ; Determine the verification results. Substitute the obtained values ​​into the four inequalities for calculation. If all four inequalities are true, the thermal stress release and load-bearing capacity of the support structure under the current design parameters are deemed to meet safety requirements; if any inequality is false, the anchoring component parameters or steel structure cross-sectional dimensions need to be adjusted, and the verification should be performed again.

[0039] The specific implementation method for thermal displacement compensation during piping installation and operation is as follows: This step aims to transform the pre-set structural functions into actual engineering results through physical installation techniques and dynamic response mechanisms. The process specifically includes the following operational and response phases: Establish a normal temperature reference state. With the system in a cold environment, hoist and fix the piping system to the crossbeam clamps of the portal frame. At this point, securely lock the positioning anchor plate 3 to the concrete foundation using fasteners. Since the circular hole and bolt at this location use the aforementioned small-clearance fit, this connection point, after tightening, is physically defined as the zero-displacement reference point of the entire support system, establishing the absolute coordinate origin of the system in three-dimensional space. For the thermal stress relief anchor plate 4 on the other side, when installing the connecting bolts, ensure that the bolt shank is located in the preset initial position within the elongated hole. This initial position is based on the fact that, in the direction of thermal expansion along the crossbeam, a free sliding stroke greater than the theoretical thermal expansion must be reserved to prevent the bolt shank from prematurely contacting the edge of the hole wall under hot conditions.

[0040] Thermal deformation response stage. As the high-temperature gas-cooled reactor comes into operation, the temperature of the medium inside the pipes gradually increases. Heat is conducted to the steel frame through the pipe clamps, causing significant elongation deformation of the transverse steel structure 2 along its axial direction. During this dynamic process, due to the rigid constraint at the positioning end restricting the movement of the vertical steel structure 1 on that side, the thermal expansion potential energy of the transverse steel structure 2 can only drive the floating end vertical steel structure 1 to extend unidirectionally outward. At this time, the thermal stress release anchor plate 5 undergoes horizontal displacement along with the column, while the anchor bolts anchored to the foundation remain stationary. From the perspective of relative motion, the connecting bolts undergo controlled relative sliding along the long axis of the elongated hole.

[0041] Achieving dynamic equilibrium through stress release. When the system reaches its design operating temperature and maintains thermal equilibrium, the support structure undergoes a geometric reconstruction from its room-temperature state to its high-temperature state. During this process, the structural characteristics of the elongated holes effectively eliminate the rigid resistance of the connecting bolts to the thermal deformation of the steel structure, transforming the enormous thermal stress that would otherwise accumulate within the structure into free macroscopic displacement at the structural ends. This thermal deformation-sliding-stress release mechanism forms an adaptive unloading process, ensuring that the combined stress within the portal frame remains within the material's allowable stress range, while simultaneously preventing destructive horizontal thrust on the concrete foundation due to hindered thermal expansion.

[0042] Please see the appendix Figure 1 - Appendix Figure 3 A thermal stress relief device for a support structure suitable for high-temperature gas-cooled reactors, comprising: The main body of the portal frame consists of two vertical steel structures 1 and a horizontal steel structure 2 connecting the tops of the two vertical steel structures 1; The positioning anchor plate 3 is fixedly connected to the bottom of one of the vertical steel structures 1, and the positioning anchor plate 3 has a circular through hole for forming a fixed support. The thermal stress relief anchor plate 4 is fixedly connected to the bottom of another vertical steel structure 1. The thermal stress relief anchor plate 4 has an elongated hole for forming a one-way sliding support. The long axis of the oblong hole is parallel to the axial direction of the transverse steel structure 2, and the length of the oblong hole is greater than the sum of the theoretical thermal expansion of the transverse steel structure 2 under the design temperature difference and the diameter of the fastener.

[0043] The portal frame structure serves as the main body to bear the gravity load of the high-temperature pipeline and acts as the foundation for thermal deformation, thus ensuring the spatial stability of the pipeline system. It consists of two vertical steel structures 1 and a horizontal steel structure 2 connecting the tops of the two vertical steel structures 1. The vertical steel structures 1 vertically transfer the pipeline load to the foundation, while the horizontal steel structure 2 connects the two side columns and generates the main thermal expansion deformation along the axial direction under high-temperature conditions. A positioning anchor plate 3 is fixedly connected to the bottom of one of the vertical steel structures 1, and is used in conjunction with anchor bolts to rigidly anchor this side of the vertical steel structure 1 to the concrete foundation, thereby establishing a zero-displacement reference point for the entire device and preventing overall drift of the support under earthquake or mechanical vibration conditions. The positioning anchor plate 3 has a circular through-hole for forming a fixed support, which, in conjunction with fasteners, restricts... The radial degree of freedom is achieved, resulting in precise positioning. The thermal stress relief anchor plate 4 is fixedly connected to the bottom of another vertical steel structure 1 to create an asymmetric boundary condition that allows horizontal displacement, thereby converting the stress accumulated inside the structure due to temperature difference into macroscopic displacement for unloading. The thermal stress relief anchor plate 4 has an elongated hole for forming a unidirectional sliding support. This elongated hole works with the anchor bolts to perform directional relative sliding movement, achieving the effect of guiding the thermal expansion of the transverse steel structure 2 to be released in a specific direction. The long axis of the elongated hole is parallel to the axial direction of the transverse steel structure 2, and the length of the elongated hole is greater than the sum of the theoretical thermal expansion of the transverse steel structure 2 under the design temperature difference and the diameter of the fastener. This provides sufficient travel space for the relative movement of the fastener in the hot state, thereby avoiding rigid collision between the bolt shank and the end of the hole wall, which could cause the structure to jam.

[0044] Please see the appendix Figure 1 - Appendix Figure 3 The width of the elongated hole in the direction perpendicular to the long axis forms a clearance fit with the diameter of the connecting fastener, and the tolerance range of this clearance fit is 0.5 mm to 1.0 mm, so as to limit the lateral displacement of the thermal stress relief device of the bracket structure.

[0045] The width of the elongated hole perpendicular to the long axis is used to construct a lateral constraint boundary. This width forms a clearance fit with the diameter of the connecting fastener, thereby providing lateral stiffness while ensuring installation feasibility. The tolerance range of this clearance fit is 0.5 mm to 1.0 mm, which is used to control the lateral clearance of the connecting pair within a small range. Together with the rod of the fastener, it provides rigid blocking, achieving the effect of locking the degree of freedom in the non-thermal expansion direction. This limits the lateral displacement of the thermal stress relief device of the support structure, thereby preventing the device from overturning or becoming unstable when subjected to lateral loads.

[0046] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for relieving thermal stress in a support structure suitable for high-temperature gas-cooled reactors, characterized in that, Includes the following steps: S1. Construct a support structure with asymmetric constraint characteristics: Connect two vertical steel structures (1) vertically to the two ends of a horizontal steel structure (2) to form a portal frame. Fix a positioning anchor plate (3) at the bottom of one of the vertical steel structures (1) and fix a thermal stress relief anchor plate (4) at the bottom of the other vertical steel structure (1). S2. Set the geometric parameters of the anchoring components: Open a circular through hole on the positioning anchor plate (3) to form a fixed support, and open an elongated hole on the thermal stress relief anchor plate (4) to form a one-way sliding support. The long axis of the elongated hole is parallel to the axis of the transverse steel structure (2). S3. Perform structural strength verification: Based on the pipeline load and structural parameters, perform multi-dimensional stress verification on the support structure to verify whether the structural stress meets the elastic design requirements. S4. Implement thermal displacement compensation for piping installation and operation: The positioning anchor plate (3) is fastened to the foundation with fasteners as a fixed reference, and the thermal stress relief anchor plate (4) is movably connected to the foundation with fasteners. Under hot operation, the thermal stress is released by the relative displacement generated by the thermal stress relief anchor plate (4) along the long axis of the elongated hole.

2. The method for relieving thermal stress in a support structure suitable for high-temperature gas-cooled reactors according to claim 1, characterized in that, In the step of setting the geometric parameters of the anchoring assembly, the total length of the elongated hole along the major axis is configured to include at least two parts: the first part is the nominal diameter of the fastener and the second part is the thermal displacement compensation amount. The logic for determining the thermal displacement compensation amount is as follows: obtain the linear expansion coefficient of the transverse steel structure (2), the span distance between the center lines of the two vertical steel structures (1) and the design temperature difference, define the product of the three as the theoretical thermal expansion amount, and multiply the theoretical thermal expansion amount by a safety factor greater than 1 to obtain the thermal displacement compensation amount.

3. The method for relieving thermal stress in a support structure suitable for high-temperature gas-cooled reactors according to claim 1, characterized in that, In the step of setting the geometric parameters of the anchoring assembly, the width of the elongated hole in the direction perpendicular to the long axis is set to be consistent with the diameter of the circular through hole on the positioning anchor plate (3), and the width dimension has a clearance fit with the diameter of the connecting fastener to limit the lateral displacement of the vertical steel structure (1) in the direction perpendicular to the axis of the horizontal steel structure (2).

4. The method for relieving thermal stress in a support structure suitable for high-temperature gas-cooled reactors according to claim 1, characterized in that, The steps for performing structural strength verification include a first verification condition and a second verification condition; The first verification condition includes verifying that the average shear or bending stress caused by horizontal loads must not exceed 60% of the material's yield strength; The second verification condition includes verifying that the sum of the compressive stress caused by the vertical load and the stress caused by 30% of the horizontal load must not exceed 40% of the material's yield strength.

5. A method for relieving thermal stress in a support structure suitable for high-temperature gas-cooled reactors according to claim 4, characterized in that, The steps for performing structural strength verification also include a third verification condition and a fourth verification condition; The third verification condition includes verifying that the bending stress calculated based on the horizontal load and the effective height of the vertical steel structure (1), after being corrected by introducing a moment reduction factor of 0.15 based on the stiffness distribution characteristics of the portal frame, shall not exceed 60% of the material yield strength. The fourth verification condition includes verifying that the sum of the normalized axial stress term and the normalized bending stress term does not exceed 1.

0.

6. A method for relieving thermal stress in a support structure suitable for high-temperature gas-cooled reactors according to claim 5, characterized in that, The step of performing structural strength verification also includes: If any of the first to fourth verification conditions is not met, then return to adjust the geometric parameters of the elongated hole or adjust the cross-sectional dimensions of the vertical steel structure (1) and the horizontal steel structure (2) until all verification conditions are met simultaneously.

7. A method for relieving thermal stress in a support structure suitable for high-temperature gas-cooled reactors according to claim 2, characterized in that, The safety factor is set to a range of 1.2 to 1.5 to cover construction and installation errors, deformation in non-uniform temperature fields, and displacement margin under seismic conditions.

8. The method for relieving thermal stress in a support structure suitable for high-temperature gas-cooled reactors according to claim 1, characterized in that, In the step of implementing thermal displacement compensation for pipe system installation and operation, under normal temperature installation conditions, the fastener rod at the thermal stress relief anchor plate (4) is positioned at a preset initial position in the elongated hole. This preset initial position has a free stroke greater than the theoretical thermal expansion in the direction away from the positioning anchor plate (3).

9. A thermal stress relief device for a support structure suitable for high-temperature gas-cooled reactors, applied to the method described in any one of claims 1-8, characterized in that, include: The main body of the portal frame consists of two vertical steel structures (1) and a horizontal steel structure (2) connected between the tops of the two vertical steel structures (1); The positioning anchor plate (3) is fixedly connected to the bottom of one of the vertical steel structures (1), and the positioning anchor plate (3) is provided with a circular through hole for forming a fixed support; The thermal stress relief anchor plate (4) is fixedly connected to the bottom of another vertical steel structure (1), and the thermal stress relief anchor plate (4) is provided with an elongated hole for forming a one-way sliding support. Wherein, the long axis of the elongated hole is parallel to the axial direction of the transverse steel structure (2), and the length of the elongated hole is greater than the sum of the theoretical thermal expansion of the transverse steel structure (2) under the design temperature difference and the diameter of the fastener.

10. A thermal stress relief device for a support structure suitable for high-temperature gas-cooled reactors according to claim 9, characterized in that, The width of the elongated hole in the direction perpendicular to the long axis forms a clearance fit with the diameter of the connecting fastener, and the tolerance range of this clearance fit is 0.5 mm to 1.0 mm, so as to limit the lateral displacement of the thermal stress relief device of the bracket structure.

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