Integral installation method for reactor pressure vessel metal reflector insulation

Abstract

The application provides a whole installation method of a reactor pressure vessel metal reflection heat preservation layer, comprising the following steps: S1, measuring the wall and ground of a reactor cavity and the outer surface of a reactor pressure vessel to obtain actual size data and establish a virtual installation model; S2, assembling a heat preservation layer support, a heat preservation block and a flow guide lining plate into a heat preservation layer module outside a nuclear island plant; S3, hoisting the heat preservation layer module to the reactor cavity and monitoring the gap between the heat preservation layer module and the wall of the reactor cavity in real time based on the virtual installation model; S4, fixing the heat preservation layer module in the reactor cavity; and S5, installing a lower neutron shielding component after the heat preservation layer module is fixed, and hoisting the reactor pressure vessel to the inside of the heat preservation layer module. The application significantly shortens the construction critical path period of a nuclear island, realizes the transformation of the quality control mode from "post-inspection" to "pre-control", and eliminates the hoisting collision risk from the process control level.

Description

Technical Field

[0001] This invention relates to a method for constructing a pressurized water reactor nuclear power plant, and more particularly to an installation process for a metal reflective insulation layer on a reactor pressure vessel. Background Technology

[0002] The reactor pressure vessel (RPV) is the core main equipment of a pressurized water reactor nuclear power plant, and its exterior is equipped with a metallic reflective insulation layer. This metallic reflective insulation layer typically consists of multiple layers of stainless steel foil reflectors, insulation blocks, flow-guiding linings, and supporting steel structures, surrounding the reactor pressure vessel cylinder, nozzles, and bottom head. The insulation layer serves two purposes: firstly, it reduces heat loss from the reactor pressure vessel; secondly, in the event of a severe core meltdown accident, the annular cavity between the insulation layer and the outer wall of the reactor pressure vessel allows for the flow of cooling water, enabling water injection for cooling of the reactor cavity and trapping the molten core within the reactor pressure vessel.

[0003] The installation of the metal reflective insulation layer is a critical step in the construction of the nuclear island of a nuclear power plant. The quality of the installation directly affects the control of the ambient temperature around the reactor pressure vessel and the fulfillment of severe accident functions during nuclear power plant operation. Furthermore, the insulation layer installation is located on the critical path of nuclear power plant construction, and its schedule and quality have a significant impact on the overall construction progress of the nuclear island.

[0004] Currently, the installation of metal reflective insulation layers for reactor pressure vessels mainly follows these methods: A conventional installation method involves installing components layer by layer within the reactor crater (also known as the reactor cavity). Specifically, insulation layer supports are first welded or bolted layer by layer onto the steel walls of the reactor crater. Insulation blocks are then installed layer by layer on the supports, followed by flow guide plates installed inside the insulation blocks. Next, auxiliary components such as neutron shielding blocks are installed, and finally, the reactor pressure vessel is hoisted into place. The main work of this installation method is completed within the crater. Due to the limited space inside the crater, scaffolding must be erected. Workers and equipment must perform multiple processes within this confined space, including support installation, insulation block assembly, and flow guide plate fixing. The large number of components installed on-site, the limited working space, and the high risk of collision between the insulation layer and flow guide plates and surrounding structures during hoisting and transportation further complicate matters. Additionally, the extensive welding, measurement, and adjustment work within the reactor cavity consumes critical path time in nuclear power plant construction, resulting in a long construction period.

[0005] Another installation method involves prefabricating and assembling the insulation layer of the reactor cylinder section within the nuclear island building, and then hoisting the prefabricated insulation layer as a whole into the reactor shaft. This method typically uses channel steel rings as auxiliary assembly tools. Connecting rings, hangers, and cylinder insulation panels are assembled layer by layer onto a pre-erected platform within the building to form a prefabricated whole. A circular crane is then used to hoist the prefabricated whole into the reactor shaft and place it on jacks on the pressure vessel support. Subsequently, the reactor pressure vessel is hoisted, allowing the pressure vessel cylinder to penetrate the prefabricated insulation layer. After the pressure vessel has descended a certain distance, the support rings of the insulation layer are installed above the pressure vessel nozzle and connected to the hangers. Finally, the channel steel rings, jacks, connecting plates, adjusting plates, and other auxiliary tools are removed, and the pressure vessel is positioned.

[0006] While this method allows some assembly work to be carried out before the pressure vessel arrives, shortening the installation period to some extent, it still has shortcomings: Firstly, the channel steel rings used to maintain the roundness and rigidity of the insulation layer are bolted, and the insulation panels are mostly riveted with blind rivets. The overall diameter and height are relatively large, making the channel steel rings and insulation layer prone to deformation under their own weight during hoisting, affecting installation accuracy. Secondly, the gap between the outer surface of the insulation layer and the inner wall of the reactor cavity is small, making it easy for the insulation layer to touch the surface of the reactor cavity during hoisting, causing damage. Furthermore, the final connection between the insulation layer and the pressure vessel shell still needs to be carried out inside the reactor cavity. The working space inside the reactor cavity is confined, and construction difficulties and safety risks remain. Additionally, after hoisting, auxiliary tooling such as the channel steel rings needs to be removed, increasing the number of steps.

[0007] Another installation method involves hoisting the metal reflective insulation layer of the cylinder section into the reactor cavity layer by layer and section by section before installing the pressure vessel, and then fixing it to the steel brackets and annular steel supports on the reactor cavity wall. After the pressure vessel is in place, the insulation layers of the nozzles and bottom head sections are then hoisted into the reactor cavity layer by layer and section by section and installed. This method directly fixes the insulation layer of the cylinder section to the reactor cavity wall using brackets, avoiding insulation installation work around the hoisted pressure vessel and eliminating the need to remove auxiliary load-bearing fixtures after hoisting.

[0008] However, this type of installation is still essentially a segmented installation within the reactor cavity. After the civil engineering structure of the reactor pit is delivered, a large amount of welding and adjustment work needs to be carried out inside the reactor cavity, including spot welding, pre-installation, inspection and adjustment, full welding of multi-layer steel brackets, positioning and adjustment of multi-layer annular steel supports, hole expansion correction, and bolt tightening. Subsequently, insulation boards and flow guide liners need to be installed layer by layer inside the reactor cavity. The reactor cavity has a large number of support components, high installation accuracy requirements, and narrow space, so the workload of on-site installation and adjustment is still large and the construction period is long.

[0009] In addition, there is an integrated insulation module solution. After the insulation components are prefabricated and assembled outside the nuclear island building, the insulation module is hoisted as a whole into the reactor pit. It is then attached to the support structure at the top of the reactor pit via an upper support structure (such as lugs or rings) located on the upper end of the insulation component. A horizontal limiting structure is installed at the bottom to restrict the horizontal displacement of the insulation module. This method decouples the insulation module from the civil structure, optimizing the segmented installation in the reactor pit into an integrated hoisting, reducing the amount of on-site welding and adjustment work in the reactor pit.

[0010] However, this type of solution mainly relies on the upper mechanical structure and the bottom horizontal limiter to achieve positioning after placement. It lacks effective process control means for the narrow gap between the insulation module and the reactor cavity wall during hoisting and descent. It is difficult to know and dynamically adjust in real time whether the insulation module will collide with the wall during hoisting into the reactor cavity and whether the gap meets the requirements. There is still a risk of damage to the insulation layer due to assembly errors, hoisting deformation or position deviation.

[0011] In summary, the existing installation process for metal reflective insulation layers in reactor pressure vessels still has room for improvement in terms of workload within the reactor cavity, risk control of impacts during hoisting, installation accuracy assurance, and critical path schedule. Summary of the Invention

[0012] The technical problem to be solved by the present invention is to overcome the defects of the existing reactor pressure vessel metal reflective insulation layer installation process, such as large amount of work inside the reactor cavity, difficulty in early detection and correction of dimensional deviations during the assembly stage, lack of real-time monitoring of narrow gaps during hoisting, resulting in a high risk of collision damage and long installation cycle, and to provide an installation process for reactor pressure vessel metal reflective insulation layer.

[0013] The present invention solves the above-mentioned technical problems through the following technical solution: A method for integrally installing a metal reflective insulation layer on a reactor pressure vessel, characterized by the following steps: S1. Measure the walls, floor and outer surface of the reactor cavity and the reactor pressure vessel to obtain actual size data, and establish a virtual installation model based on the designed placement position of the reactor pressure vessel. S2. Outside the nuclear island plant, the insulation layer support, insulation block and flow guide plate are assembled into an insulation layer module. During the assembly process, the external dimension data of the insulation layer module is collected, and the external dimension data is imported into the virtual installation model for pre-installation verification. The assembly size is adjusted according to the verification results so that the distance between the flow guide plate and the outer wall of the reactor pressure vessel and the distance between the insulation layer module and the wall of the reactor cavity meet the installation requirements. S3. The qualified insulation layer module is hoisted into the reactor cavity as a whole. During the hoisting and descent, the position of the insulation layer module is measured in real time, and the gap between the insulation layer module and the wall of the reactor cavity is monitored in real time based on the virtual installation model. S4. Position and fix the insulation layer module in the stack cavity; S5. After the insulation layer module is in place and fixed, install the lower neutron shielding component, and then hoist the reactor pressure vessel into place inside the insulation layer module.

[0014] By utilizing the aforementioned integrated installation method, much of the assembly work that was originally performed inside the reactor cavity is transferred to a spacious area outside the nuclear island building. During assembly, digital pre-installation verification is conducted based on the measured dimensions of the reactor cavity and pressure vessel to identify and correct dimensional deviations in advance, preventing errors from accumulating layer by layer. Simultaneously, during the hoisting and descent process, real-time quantitative monitoring and dynamic adjustment of the narrow gap between the insulation module and the reactor cavity walls are performed using a virtual installation model. This effectively reduces the risk of damage to the insulation layer during hoisting, improves installation accuracy and first-pass yield, and significantly shortens the on-site work time inside the reactor cavity, thereby shortening the critical path construction period of the nuclear power plant.

[0015] According to one embodiment of the present invention, the step S1 of arranging measurement points on the walls and ground of the reactor cavity and the outer surface of the reactor pressure vessel includes: evenly distributing measurement points at predetermined intervals along the height and horizontal directions on the steel walls of the reactor cavity; evenly distributing measurement points at predetermined intervals along the front-back and left-right directions on the ground of the reactor cavity; evenly distributing measurement points at predetermined intervals along the axial direction and at predetermined angles along the circumferential direction on the cylinder of the reactor pressure vessel; evenly distributing measurement points at predetermined angles along the circumferential direction on the nozzle of the reactor pressure vessel; and evenly distributing measurement points at predetermined angles along the circumferential direction on the outer surface of the flange of the reactor pressure vessel.

[0016] By systematically arranging measurement points at predetermined intervals and angles on the walls, ground, and key parts of the reactor cavity, such as the pressure vessel shell, nozzles, and flanges, we can comprehensively obtain the actual three-dimensional dimensional data of the reactor cavity and pressure vessel. This provides a sufficient data foundation for the accurate establishment of the virtual installation model, which enables the digital model used for subsequent pre-installation verification and gap monitoring to accurately reflect the actual spatial geometric relationships.

[0017] According to an embodiment of the present invention, in step S1, a laser tracker is used to collect data on the measurement points arranged on the walls, ground and outer surface of the reactor pressure vessel in the reactor cavity. The virtual installation model is established based on the centerline of the reactor pressure vessel after it is in place, the center elevation line of the nozzle, multiple position axes and the levelness of the flange bearing surface.

[0018] High-precision three-dimensional coordinate measurement is performed using a laser tracker, and a unified coordinate system is modeled using four benchmarks: centerline, elevation line, azimuth axis, and flange levelness. This ensures the consistency of coordinates between the virtual installation model and the actual installation space. This allows the pre-installation verification results and real-time gap monitoring data to accurately reflect the positional relationship of the insulation layer module in the real space, avoiding systematic deviations caused by inconsistent benchmarks.

[0019] According to one embodiment of the present invention, the allowable deviation of the nozzle center elevation line is ±1mm, the allowable deviation of the position axis is ±1mm, and the levelness of the flange bearing surface is less than or equal to 0.3mm.

[0020] By setting strict deviation limits for the modeling benchmark, it can be ensured that the virtual model itself, which serves as the benchmark for all subsequent pre-verification and hoisting monitoring comparisons, has sufficient accuracy. This allows the ±1 mm level gap verification requirements during the assembly stage and the narrow gap monitoring during the hoisting stage to be established on a reliable benchmark, avoiding installation dimension deviations due to benchmark error transmission.

[0021] According to an embodiment of the present invention, in step S1, the virtual installation model simulates: the assembly elevation and levelness of the insulation layer module; the positioning dimensions of the insulation layer module relative to the center line of the reactor pressure vessel; the distance between the flow guide liner and the outer wall of the reactor pressure vessel; and the distance between the limiting support working end face of the insulation layer bracket and the wall of the reactor cavity.

[0022] By simulating the above four types of key dimensions in the virtual installation model in advance, clear comparison benchmarks can be provided for the pre-installation verification in the subsequent assembly stage and the real-time gap monitoring in the hoisting stage. This allows for targeted verification of whether the key gaps meet the requirements after each layer or local module is completed during the assembly process, avoiding omission of key dimension inspection items.

[0023] According to an embodiment of the present invention, step S2 includes: S 21 A liftable operating platform is installed at the assembly site outside the nuclear island plant. S 22 1. Lay out the layout according to the positioning dimensions determined by the virtual installation model; S 23 The insulation layer support, the insulation block and the flow guide plate are assembled into an integral insulation layer module, or they are assembled into multiple local modules in parallel in multiple layers and multiple areas and then spliced ​​together into an insulation layer module.

[0024] By configuring a liftable operating platform in a spacious area outside the nuclear island plant and using a virtual model for positioning and layout, a good working environment and accurate positioning benchmarks can be provided for the assembly work. It also supports two methods: overall assembly or parallel assembly of modules. This allows for flexible selection of assembly strategies based on the on-site hoisting equipment capacity and schedule requirements. When there is sufficient hoisting capacity, overall assembly can be used to reduce splicing work, while multi-module parallel assembly can be used to shorten the assembly period when it is necessary to speed up the progress.

[0025] According to an embodiment of the present invention, in step S2, the insulation layer support adopts a combinable support structure, which can individually support the weight of one of the overall insulation layer modules or each of the local modules. The assembly process of the insulation layer bracket includes: first, installing and temporarily fixing the lower vertical support; installing the lower insulation layer support on the lower vertical support; assembling the lower insulation block and the lower flow guide plate on the lower insulation layer support to form the lower module; assembling each middle module layer by layer on the layered assembly platform; and then splicing each middle module with the lower module sequentially on the overall assembly platform.

[0026] A modular support structure, which is a permanent component (unlike temporary auxiliary load-bearing fixtures such as channel steel rings that need to be removed after hoisting), is used. Once hoisted into place along with the insulation layer modules, the support structure does not need to be removed, reducing the need to dismantle auxiliary fixtures within the reactor cavity. Assembly and splicing are performed layer by layer from the lower modules to the middle modules, with a clear assembly path that facilitates quality control. This allows dimensional deviations during assembly to be detected and corrected promptly during layer-by-layer splicing, preventing deviations from accumulating and amplifying after multiple layers of assembly.

[0027] According to an embodiment of the present invention, in step S2, for each assembled integral insulation layer module or each partial module, external dimension data is collected, and the collected external dimension data is imported into the virtual installation model for pre-installation verification. The distance between the flow guide liner of the integral insulation layer module or the partial module and the outer wall of the reactor pressure vessel, and the distance between the limiting working end face of the insulation layer support limiting block and the wall of the reactor cavity are checked to see if they meet the installation requirements. Only after passing the verification can the assembly of the next layer of integral insulation layer module or the partial module be carried out.

[0028] By performing pre-installation verification layer by layer and module by module (instead of checking all at once after assembly), each layer or local module is simulated in the virtual model to check whether the two key gaps meet the requirements. This allows for the timely detection and adjustment of dimensional deviations in that layer or local module. This ensures that deviations are eliminated before they are passed on to subsequent assembly, effectively avoiding more than 90% of local gap and distance deviations, and significantly improving assembly accuracy and first-pass yield.

[0029] According to an embodiment of the present invention, in step S2, the arrangement of measurement points during the acquisition of external dimension data includes: evenly distributing measurement points every 90° along the circumference on the lower vertical support; evenly distributing measurement points along the axial direction at predetermined intervals and along the circumference at predetermined angles on the outer surface of the flow guide liner; setting measurement points at the four corners and center of the limiting working end face of the insulation layer support limiting block; and using a laser tracker to acquire data from each measurement point.

[0030] By systematically arranging measurement points at three key locations—the support structure, the surface of the flow guide liner, and the limiting working end face—and collecting data using a laser tracker, the actual external dimensions of the assembled parts can be comprehensively obtained. This ensures that the data imported into the virtual installation model can accurately reflect the geometry of the insulation layer module, providing reliable data for precise pre-installation verification.

[0031] According to an embodiment of the present invention, in step S2, meeting the installation deviation requirement includes: When the lower insulation layer is installed, its elevation deviation is ±1mm, its levelness is no more than 1mm, and its distance deviation from the center line of the reactor pressure vessel is ±1mm. After the insulation blocks are assembled, the gap between adjacent insulation blocks shall not exceed 2mm, and the allowable deviation of the inner circle radius formed by the insulation blocks shall be ±2mm. After the flow guide liner is installed, the allowable deviation between the flow guide liner and the center line of the reactor pressure vessel is ±1mm. During pre-installation verification, the allowable deviation of the distance between the limiting working end face of the insulation layer support limiting block and the wall of the reactor cavity is ±1mm. The allowable deviation between the flow guide liner and the outer wall of the reactor pressure vessel is ±1mm.

[0032] By setting millimeter-level deviation limits for each key installation dimension, the geometric accuracy of the insulation module can be strictly controlled during the assembly stage. This ensures that the assembled insulation module maintains a uniform gap with the reactor cavity and pressure vessel in the virtual model, meeting design requirements. This allows for controllable gaps around the insulation module when it is hoisted into the reactor cavity, providing a safety margin for subsequent orientation adjustments during hoisting.

[0033] According to an embodiment of the present invention, in step S3, the qualified insulation layer module is transported to the reactor cavity by a large crawler crane or directly hoisted. During hoisting, a lifting device with leveling adjustment capability is used to connect to the top of the insulation layer module.

[0034] Using a large crawler crane as the lifting equipment, along with a lifting device that has the ability to adjust the level, can adjust the horizontal posture of the insulation layer module during the lifting process, keeping the insulation layer module horizontally stable during descent. This can prevent collisions caused by the insulation layer module tilting and resulting in too small a gap on one side.

[0035] According to one embodiment of the present invention, in step S3, when the insulation layer module is hoisted above the installation position of the reactor cavity, the following centering operation is performed: The centering mark on the monitoring device set at the bottom of the insulation layer module is monitored by a total station located at the bottom of the cavity; the orientation of the insulation layer module is adjusted by a traction rope so that the insulation layer module is aligned in position and direction before the hook is slowly lowered.

[0036] Using a total station, the alignment marks at the bottom of the insulation module are monitored in real time without contact. Combined with the traction rope for horizontal adjustment, rapid coarse alignment can be completed before the insulation module enters the reactor cavity. This ensures that the insulation module is aligned with the reactor cavity entrance in the correct orientation and horizontal position, creating good initial positioning conditions for fine gap monitoring when entering the narrow reactor cavity.

[0037] According to one embodiment of the present invention, after the monitoring device is assembled in step S2, it is installed below the bottom guide liner of the insulation layer module. The installation and adjustment of the monitoring device includes the following steps: A monitoring device is provided, including an adjustable bracket and an alignment mark, wherein the alignment mark is disposed on the base of the adjustable bracket and the adjustable bracket has multiple adjustable legs; The adjustable bracket is initially installed at the bottom of the lower guide plate; Adjust the length of each of the adjustable legs so that the center of the centering mark coincides with the center line of the reactor pressure vessel laid out on the assembly platform; When the overlap deviation is less than or equal to 0.3 mm, fix each of the adjustable legs.

[0038] By installing and fine-tuning the bottom monitoring device during the assembly stage, the center of the alignment mark can be precisely aligned with the layout point of the reactor pressure vessel centerline (with a deviation of no more than 0.3 mm). This provides a reliable reference for subsequent coarse alignment by the total station. This ensures that the position of the alignment mark monitored by the total station at the bottom of the reactor cavity can accurately reflect the actual offset of the insulation module relative to the pressure vessel centerline, thus guaranteeing the accuracy of coarse alignment.

[0039] According to an embodiment of the present invention, in step S3, a multi-layer laser tracker monitoring target base is arranged on the outside of the lower flow guide liner of the insulation layer module. When the bottom of the insulation layer module approaches the upper inlet of the reactor cavity, the laser receiving target ball displacement on each monitoring target base is measured by the laser tracker, and the gap between the insulation layer module and the wall of the reactor cavity is monitored in real time based on the virtual installation model to control the descent.

[0040] A laser tracker, along with a monitoring target and a laser receiving target ball, is used to perform high-precision real-time measurements of the insulation module as it enters the reactor cavity. The real-time measurement data is compared with a virtual installation model to quantify the monitoring of the surrounding clearance. This allows for millimeter-level real-time monitoring and dynamic feedback of the clearance around the insulation module after it enters the narrow reactor cavity entrance. This enables operators to promptly identify which side has a smaller clearance and adjust its position using methods such as traction ropes, effectively preventing damage from collisions between the insulation module and the reactor cavity walls. Compared to traditional methods relying on visual observation by operators or post-incident inspection via a laser ball, digital real-time clearance monitoring transforms risk control from post-inspection to process control.

[0041] According to an embodiment of the present invention, step S3 further includes the following monitoring operation: The laser tracker monitoring target base is provided with at least three layers along the outer side of the lower guide liner, with multiple monitoring target bases evenly distributed in each layer along the circumference. When the insulation layer module enters the upper inlet of the stack cavity, its descent speed is less than 0.3 m / min; Monitor changes in the hoisting load in real time. When the change in the hoisting load exceeds the predetermined threshold, stop the descent immediately and investigate the cause.

[0042] 360-degree all-around clearance monitoring is achieved by arranging multiple layers of circumferentially distributed monitoring targets on the outer side of the lower guide liner; sufficient reaction time is provided for azimuth adjustment by limiting the descent speed to no more than 0.3 m / min. By monitoring sudden changes in the lifting load (e.g., stopping the machine if it exceeds 1500 N), possible jamming or collision signs can be detected in a timely manner. The synergistic effect of multiple protection measures ensures the safe and smooth conduct of lifting activities in confined spaces.

[0043] According to one embodiment of the present invention, in step S4, after the vertical support of the insulation layer module is fully in place, the vertical support is fixedly connected to the cavity wall and / or bottom.

[0044] According to one embodiment of the present invention, after the vertical support is fixed, the hoisting tools are removed, and the laser tracker measuring target and bottom monitoring device installed on the insulation layer module for hoisting monitoring are removed.

[0045] By fixing the vertical supports to the cavity walls and / or bottom (unlike the top-mounted scheme where the insulation modules are not bolted to the sump and the horizontal limiters only abut against each other), the insulation modules can form a stable fixed connection within the cavity, improving the structural stability of the insulation layer under normal and seismic conditions. Furthermore, it is clearly stated that only the measuring fixtures used for hoisting monitoring are removed, not the load-bearing support structure; the insulation layer support is retained as a permanent support structure. This is fundamentally different from schemes that require the removal of temporary load-bearing auxiliary fixtures such as channel steel rings and jacks.

[0046] The positive and progressive effects of this invention are as follows: The overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention has the following advantages: I. Significantly shorten the critical path construction period of the nuclear island: The work of installing a large number of supports, assembling insulation blocks, and adjusting dimensions, which was originally completed in the narrow reactor cavity, is transferred to the spacious area outside the nuclear island plant for modular assembly. On-site work in the reactor cavity only requires the installation of accessories such as the lower neutron shield, hoisting path inspection, overall hoisting and final placement. The on-site operation time is shortened from 3 to 4 months in the traditional process to about 20 days. Compared with the top-mounted integrated insulation module solution (within one month), the on-site construction period is further shortened.

[0047] Second, the quality control model is transformed from "post-inspection" to "pre-control": During the assembly stage, each layer and each local module is pre-installed and verified through a virtual installation model. Dimensional deviations can be detected and corrected in advance, which can effectively avoid more than 90% of local gaps and distances exceeding tolerance. This solves the problem that in the segmented installation method, the air gap can only be checked and the problem can be found and rectified after the RPV is in place by means of ball passing.

[0048] Third, eliminate the risk of collisions during hoisting from the process control level: adopt a dual-equipment digital collaborative solution of "coarse centering at the bottom of the total station and fine monitoring of the upper multi-layer target base of the laser tracker". After the insulation layer enters the narrow stack cavity entrance, the gap around it is monitored in real time at the millimeter level. With the low-speed descent and load change shutdown protection, the operator can dynamically adjust the orientation, which effectively solves the shortcomings of the overall hoisting method, which makes it difficult to detect collisions in narrow gaps in time by visual observation, and the lack of digital monitoring of the hoisting process in the top-mounted method.

[0049] IV. More Rational and Reliable Support Structure System: The modular support structure, which is a permanent component of the insulation layer, is fixedly connected to the cavity wall and / or bottom after being in place. Unlike the channel steel ring auxiliary tooling scheme, it does not require the removal of temporary load-bearing structures inside the cavity. It also has higher structural stability than the hanging lug suspension + bottom horizontal limiter in the top-hanging scheme, which only abuts against each other without connection. This is conducive to improving the safety of the insulation layer under normal working conditions and seismic conditions.

[0050] V. Improve the working environment and enhance construction safety: A large number of operations have been moved from the confined and narrow stack cavity to a spacious area outside the plant (equipped with a liftable operating platform), reducing the time spent on scaffolding erection, working in confined spaces at high altitudes, and exposure to welding fumes. At the same time, it avoids the safety risks of long-term and repeated heavy-load operation of the ring crane and working around the suspended pressure vessel.

[0051] VI. Promoting the digital upgrade of nuclear power installation processes: The systematic integration of high-precision digital measurement equipment such as laser trackers and total stations into the entire process of "modeling-assembly pre-verification-hoisting monitoring" has enabled the insulation layer installation to transform from the traditional process of "experience + tooling + manual tape measure measurement" to a digital process of "digital model driven + real-time data feedback". This provides a replicable process paradigm for the overall installation of similar large ring components in confined spaces. Attached Figure Description

[0052] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, in which the same reference numerals always denote the same features, wherein: Figure 1 This is a schematic diagram of the installation method of the metal reflective insulation layer of a conventional reactor pressure vessel.

[0053] Figure 2 This is a schematic diagram of the installation room model in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0054] Figure 3 This is a schematic diagram of the reactor pressure vessel model in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0055] Figure 4 This is a schematic diagram of the installation model of the metal reflective insulation layer in the reactor pressure vessel of the present invention.

[0056] Figure 5 This is a schematic diagram showing the axis markings of the installation position in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0057] Figure 6This is a schematic diagram illustrating the assembly of the lower insulation layer at an assembly site outside the nuclear island building, in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0058] Figure 7 This is a schematic diagram showing the arrangement of measurement points after the lower insulation layer is assembled in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0059] Figure 8 for Figure 7 A partial enlarged view of the measurement points on the working end face of the middle insulation layer support limiting block.

[0060] Figure 9 This is a schematic diagram showing the inspection of the lower insulation layer in the installation model in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0061] Figure 10 This is a schematic diagram of the assembly of the first layer of the middle insulation layer in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0062] Figure 11 This is a schematic diagram of the first layer of the middle insulation layer in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0063] Figure 12 for Figure 11 A partially enlarged schematic diagram of the measurement points on the working end face of the middle insulation layer support limiting block.

[0064] Figure 13 This is a schematic diagram of the inspection of the first layer of the middle insulation layer in the installation model in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0065] Figure 14 This is a schematic diagram illustrating the assembly of the middle insulation layer and the lower insulation layer in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0066] Figure 15 This is a schematic diagram showing the arrangement of measurement points after the first layer of the middle insulation layer and the lower insulation layer are assembled in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0067] Figure 16 This is a schematic diagram showing the inspection of the middle insulation layer and the lower insulation layer in the installation model in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0068] Figure 17 This is a schematic diagram of the assembly of the overall insulation layer in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0069] Figure 18 This is a schematic diagram of the overall insulation layer modeling in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0070] Figure 19 This is a schematic diagram of the overall insulation layer being inspected in the installation model in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0071] Figure 20 This is a schematic diagram of the monitoring device at the bottom of the overall insulation layer in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0072] Figure 21 for Figure 20 A schematic diagram viewed along direction A.

[0073] Figure 22 This is a schematic diagram of the hoisting position monitoring of the overall insulation layer in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0074] Figure 23 This is a schematic diagram of the hoisting gap monitoring of the overall insulation layer in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0075] Figure 24 This is a schematic diagram of the neutron shielding at the bottom of the overall insulation layer in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0076] Figure 25 This is a partial structural diagram of the combined support structure of the thermal insulation layer in the overall installation method of the metal reflective thermal insulation layer of the reactor pressure vessel of the present invention.

[0077] Figure 26 This is a partial structural diagram of the insulation block in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention.

[0078] Figure 27 This is a partial structural diagram of the flow guide plate of the insulation layer in the overall installation method of the metal reflective insulation layer of the reactor pressure vessel of the present invention. Detailed Implementation

[0079] The present invention will be further described below with reference to specific embodiments and accompanying drawings. More details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual application situations without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0080] Embodiments of the invention will now be described in detail with reference to the accompanying drawings. It should be noted that these and subsequent drawings are merely illustrative and are not drawn to scale, and should not be construed as limiting the scope of the invention. Wherever possible, the same reference numerals will be used in all drawings to denote the same or similar parts.

[0081] like Figures 1 to 26 As shown, this invention discloses an overall installation method for a metal reflective insulation layer of a reactor pressure vessel, which is generally implemented in the following process path: digital modeling, modular assembly and pre-verification outside the nuclear island, digital monitoring and overall hoisting, positioning and fixing, and subsequent installation.

[0082] See Figures 2 to 23 The overall installation method of the metal reflective insulation layer of the reactor pressure vessel includes the following steps: First, before installing the insulation layer, the walls 11 and the ground of the reactor cavity 10 and the outer surface of the reactor pressure vessel 12 are measured on-site to obtain actual size data, and a virtual installation model is established based on the designed placement position of the reactor pressure vessel 12 (step S1).

[0083] Here, the reactor cavity 10 can also be called the reactor pit, which refers to the concrete well-like space in the nuclear island building of a nuclear power plant that houses the reactor pressure vessel 12, and its inner wall is provided with a steel wall 11 (also known as the cavity lining or CA04 module inner wall).

[0084] The metal reflective insulation layer refers to an insulation structure composed of multiple layers of polished stainless steel foil reflective sheets. It typically includes an insulation block 30 (containing multiple layers of stainless steel reflective foil), a flow guide liner 40 (a stainless steel liner located inside the insulation block to form cooling water channels), and an insulation layer support 20 (a steel structure used to support the insulation block and the flow guide liner). The whole structure is a cylindrical structure surrounding the reactor pressure vessel 12.

[0085] Then, at the assembly site outside the nuclear island plant, the insulation layer support 20, insulation block 30, and flow guide plate 40 are assembled in a modular manner. During the assembly process, the external dimensions are collected module by module and layer by layer and imported into the virtual installation model for pre-installation verification. The assembly dimensions are adjusted in a timely manner based on the verification results (step S2).

[0086] Here, insulation module 13 refers to an insulation structure unit that is assembled outside the nuclear island building and hoisted into the reactor cavity 10 as a whole or several partial modules, including insulation layer support 20, insulation block 30, and flow guide plate 40. Insulation module 13 can be a whole module or a combination of multiple partial modules (such as a lower module and several middle modules) spliced ​​together.

[0087] The virtual installation model refers to a three-dimensional digital model constructed using digital modeling methods based on the measured dimensional data of the reactor cavity 10 and the reactor pressure vessel 12, with the designed placement position of the reactor pressure vessel 12 as the reference, to simulate the placement state of the insulation layer module 13.

[0088] The pre-installation verification refers to the process of importing the measured external dimensions of the assembled part into the virtual installation model during the assembly process, and checking whether the key dimensions of the part in the virtual positioning state (such as the distance between the flow guide liner 40 and the outer wall of the reactor pressure vessel 12, and the distance between the limiting working end face 91 of the insulation layer support limiting block 90 and the wall 11 of the reactor cavity) meet the installation requirements through digital simulation.

[0089] After assembly and verification, the insulation module 13 is hoisted as a whole into the reactor cavity 10. During the hoisting and descent, the position is measured in real time using digital measuring equipment, and the gap between the insulation module 13 and the wall 11 of the reactor cavity is monitored in real time based on the virtual installation model (step S3).

[0090] After the insulation layer module 13 is in place, it is fixed to the cavity 10 (step S4).

[0091] Finally, after the insulation layer module 13 is in place and fixed, the lower neutron shielding component 50 is installed, and the reactor pressure vessel 12 is hoisted into place inside the insulation layer module 13 (step S5).

[0092] This invention does not preclude the addition of other auxiliary processes between or before the aforementioned main process steps, such as the establishment of a clean area, finished product protection, and welding inspection. Since these auxiliary processes are not the focus of this invention, they will not be described in detail herein.

[0093] It is worth noting that although this application describes the overall installation process of the metal reflective insulation layer of the reactor pressure vessel of a pressurized water reactor nuclear power plant, the installation method based on the present invention can also be applied to the installation of other nuclear power equipment or other industrial equipment with similar large annular insulation structures that need to be precisely positioned in narrow spaces, as long as it is necessary to ensure that the large-size annular module is hoisted and positioned with high precision in a confined space during the installation of these devices, and to digitally control the assembly accuracy and hoisting gap.

[0094] Step S1: Measurement and virtual installation model establishment.

[0095] See Figures 2 to 5Before installing the insulation layer, a clean area is first established in the installation room of the reactor cavity 10, and the cleanliness of personnel, tools, and equipment entering and exiting is controlled. Then, template lines are laid out on the walls 11 (e.g., steel walls) of the reactor cavity 10 according to the corresponding outline of the insulation layer module 13, as a reference benchmark for the subsequent layout of measurement points.

[0096] In one specific embodiment, the measurement points C are arranged as follows: measurement points are evenly arranged every 300 mm along the vertical (up-down) and horizontal (left-right) directions on the walls 11 (e.g., steel walls) of the reactor cavity 10. Measurement points are also evenly arranged every 300 mm along the front-back and left-right directions on the ground of the reactor cavity 10.

[0097] For reactor pressure vessel 12, a row of measuring points is arranged axially every 300 mm on its cylinder, with multiple (e.g., 16) measuring points evenly distributed at 22.5° intervals along the circumference of each row. Multiple (e.g., 8) measuring points are evenly distributed at 45° intervals along the circumference of the nozzle. Multiple (e.g., 16) measuring points are evenly distributed at 22.5° intervals along the circumference of the outer surface of the flange. However, this is not limiting. The above-mentioned spacing and number of measuring points are preferred values ​​determined based on the insulation layer size and accuracy requirements of this embodiment. In other embodiments, the measuring point density can be adjusted according to the insulation layer diameter, height, and accuracy requirements. For example, the measuring point spacing can be selected within the range of 200 mm to 500 mm, and the number of circumferentially distributed points can be adjusted to 8, 12, 24, etc., as needed.

[0098] A laser tracker 60 was used to collect data from all measurement points arranged on the walls 11, ground, and outer surface of the reactor pressure vessel 12 within the reactor cavity, obtaining the three-dimensional coordinate data of each measurement point. Based on the collected measured data, a virtual installation model of the insulation layer was established, using the centerline B of the reactor pressure vessel 12 after its placement as the positional reference, the nozzle center elevation line D as the elevation reference, the position axes at 0°, 90°, 180°, and 270° as the azimuth reference, and the levelness of the flange bearing surface E as the horizontal reference. In one specific embodiment, the allowable deviation of the nozzle center elevation line from the design value was ±1mm, the allowable deviation of the four azimuth position axes from the design azimuth was ±1mm, and the levelness of the flange bearing surface E was no greater than 0.3mm, to ensure the accuracy of the modeling reference.

[0099] In this virtual installation model, at least the following key dimensional information is simulated: (1) the assembly elevation and levelness of the insulation layer module 13; (2) the positioning dimension of the insulation layer module 13 relative to the centerline B of the reactor pressure vessel 12; (3) the distance between the flow guide liner 40 and the outer wall of the reactor pressure vessel 12; and (4) the distance between the limiting support working end face of the insulation layer bracket 20 (i.e., the limiting working end face 91 of the insulation layer support limiting block 90) and the wall 11 of the reactor cavity. These simulated dimensions will serve as the comparison benchmark for subsequent assembly pre-verification and hoisting gap monitoring.

[0100] Step S2: Modular assembly and pre-verification outside the nuclear island plant.

[0101] See Figures 4 to 15 After the virtual installation model is established, the assembly work outside the nuclear island plant begins. A liftable operating platform 110 is set up at the assembly site outside the nuclear island plant, and the layout is carried out on the assembly site according to the positioning dimensions determined by the virtual installation model, marking the center line position of the reactor pressure vessel 12, the assembly elevation and outline of each insulation layer, and other assembly benchmarks.

[0102] In this embodiment, the insulation layer bracket 20 adopts a modular support structure. This support structure is a permanent component of the insulation layer module 13 and is hoisted into place together with the insulation layer module 13, rather than a temporary auxiliary tooling that needs to be removed after hoisting (this is fundamentally different from the solution of using temporary auxiliary tooling such as channel steel rings and jacks, which are removed after placement). The modular support structure can independently support the weight of a whole insulation layer module or individual modules. Its modular design allows the entire insulation layer to be assembled into a whole module as needed, or to be divided into multiple layers and multiple areas and assembled into multiple partial modules in parallel before splicing. In this embodiment, a layered, modular, parallel assembly method is adopted before overall splicing to improve assembly efficiency.

[0103] The specific assembly process is as follows: Step 1: Assembly of the lower module See Figure 6 First, the lower vertical support 21 is installed on the overall assembly platform 100 and temporarily fixed with temporary bolts. After the lower vertical support 21 is positioned correctly and securely fixed, the lower insulation layer support 22 is installed on it. During installation, the allowable deviation for the elevation of the lower insulation layer support 22 is ±1mm, the levelness is no more than 1mm, and the allowable deviation for its distance from the center line of the reactor pressure vessel 12 is ±1mm. After inspection and approval, it is securely tightened.

[0104] Subsequently, the lower insulation block 31 is assembled on the lower insulation layer support 22. The gap between adjacent insulation blocks is no more than 2mm, and the allowable deviation of the inner circle radius formed by the insulation blocks is ±2mm. The lower flow guide liner 41 is installed on the inner side of the lower insulation block 31. The allowable deviation of the distance between the lower flow guide liner 41 and the center line of the reactor pressure vessel 12 is ±1mm. After installation, it is firmly fixed.

[0105] Step 2: Lower Module Pre-verification

[0106] See Figures 7 to 9 After the lower module is assembled, a layer of measuring points is set every 300 mm along the axial direction on the lower vertical support 21, and multiple (e.g., 4) measuring points are evenly arranged every 90° along the circumference of each layer. A row of measuring points is set every 300 mm along the axial direction on the outer surface of the lower flow guide liner 41, and multiple (e.g., 16) measuring points 92 are evenly arranged every 22.5° along the circumference of each row. Five measuring points 92 are set at the four corners and the center of the limiting working end face 91 of the insulation layer support limiting block 90. ​​The laser tracker 60 is used to collect data from the above measuring points, and the collected external dimension data is imported into the virtual installation model and compared with the dimension model of the reactor cavity 10 to ensure that the allowable deviation of the distance h1 between the limiting working end face 91 of the insulation layer support limiting block 90 and the wall 11 of the reactor cavity is ±1 mm, and the allowable deviation of the distance h2 between the flow guide liner 40 and the outer wall of the reactor pressure vessel 12 is ±1 mm. Only after passing the inspection can the assembly of the middle module proceed.

[0107] Step 3: Layered Assembly and Pre-verification of the Middle Module

[0108] See Figures 10 to 16After the lower modules pass inspection, the middle modules are assembled layer by layer on the layered assembly platform. Taking the first layer of the middle insulation layer as an example, the middle insulation layer support 23 is assembled on the layered assembly platform, with an allowable deviation of ±1mm in elevation, no more than 1mm in levelness, and an allowable deviation of ±1mm in distance from the center line of the reactor pressure vessel 12. Then, the middle insulation blocks 32 are assembled on the middle insulation layer support 23, with a gap of no more than 2mm between each block and an allowable deviation of ±2mm in inner radius. Finally, the middle flow guide liner 42 is assembled inside the middle insulation blocks 32, with an allowable deviation of ±1mm in distance from the center line of the reactor pressure vessel 12. After the first layer of the middle insulation layer is assembled, multiple (e.g., 5) measuring points 92 are set at the four corners and center of the limiting working end face 91 of the insulation layer support limiting block 90. ​​Multiple (e.g., 16) measuring points 92 are evenly arranged on the outer surface of the middle guide liner 42 along the axial direction at intervals of 300mm and along the circumferential direction at intervals of 22.5°. Data is collected using a laser tracker 60. After modeling the module, the data is imported into the virtual installation model for pre-installation verification to check whether the above two key gaps meet the deviation requirement of ±1mm.

[0109] After the first layer of the central insulation layer passes inspection, see [link / reference]. Figures 14 to 16 The assembly is then spliced ​​and secured to the lower module using connecting bolts 101. After splicing, measurement points are arranged again to collect data (multiple measurement points are evenly distributed on the outer surface of the guide liner every 300mm along the axial direction and every 22.5° around the circumference, for example, 16 measurement points). After modeling, an overall check is performed in the virtual installation model to ensure that the cumulative splicing error does not exceed the allowable range.

[0110] In the same manner, assemble the second, third, and fourth layers of the central insulation layer in sequence (the number of layers can be determined according to the total height of the insulation layer; in this embodiment, there are four layers of central insulation layer, but this is not a limitation). After each layer is assembled, perform a pre-installation verification for that layer. After the verification is passed, splice it with the assembled parts, and perform an overall pre-installation verification again after splicing.

[0111] This invention does not preclude the use of other assembly sequences, such as assembling the lower modules and each middle module simultaneously at the assembly site, then assembling the middle modules into partial modules using combinations such as "first layer + second layer" or "third layer + fourth layer," and finally assembling them with the lower modules. This parallel assembly method can shorten the assembly period.

[0112] Step 4: Overall Assembly and Final Pre-verification

[0113] See Figures 17 to 19After all module layers are assembled and spliced, an integral insulation layer module 13 is formed. Final data acquisition is performed on the integral assembly platform 100 for the integral insulation layer module 13: measuring points are set at the four corners and center of the limiting working end face 91 of the insulation layer support limiting block 90; multiple measuring points (e.g., 16) are evenly distributed along the axial direction at 300mm intervals and circumferentially at 22.5° intervals on the outer surface of the flow guide liner 40. All data are collected using a laser tracker 60, and after modeling, the data is imported into a virtual installation model for overall pre-installation verification. This confirms that the distance between the limiting working end face 91 of the insulation layer support limiting block 90 and the reactor cavity wall 11, and the distance between the flow guide liner 40 and the outer wall of the reactor pressure vessel 12, both meet the allowable deviation requirement of ±1mm.

[0114] By employing the layered assembly and layer-by-layer verification method described above, dimensional deviations can be detected and corrected promptly during the assembly process, preventing the accumulation and propagation of errors as they accumulate. This effectively avoids over 90% of instances of local gaps and distances exceeding tolerances. Compared to the traditional method of performing a final inspection after all assembly is complete, this significantly improves assembly accuracy and the first-pass yield.

[0115] Step 5: Lifting preparation and installation of bottom alignment device

[0116] See Figure 20 and Figure 21 After the overall insulation layer module 13 passes the pre-verification and before the formal hoisting, laser tracker monitoring target bases 61 (no less than 3 layers, with 8 evenly distributed along the circumference in each layer) are arranged on the outside of the lower guide liner 41 for monitoring the upper gap during the subsequent hoisting process.

[0117] Simultaneously, a bottom monitoring device 71 is installed below the bottom guide liner of the insulation layer module 13 for rough horizontal alignment during hoisting and descent above the reactor cavity 10. The installation and adjustment of the bottom monitoring device 71 includes the following steps: (1) Provide a monitoring device including an adjustable bracket 72 and a centering mark 74 (e.g., a crosshair target), the centering mark 74 being set at the center of the base of the adjustable bracket 72, the adjustable bracket 72 having 4 adjustable legs 73.

[0118] (2) The adjustable bracket 72 is initially installed at the bottom of the lower guide plate.

[0119] (3) Gradually fine-tune the length of the four adjustable legs 73 so that the center of the centering mark 74 (crosshair target) coincides with the center line of the reactor pressure vessel 12 laid out on the overall assembly platform 100.

[0120] (4) When the overlap deviation is no more than 0.3 mm, fix each adjustable support leg 73 to keep the bottom monitoring device 71 stable.

[0121] The length of the outrigger end is less than the circumference of the flow guide liner. This ensures that the adjustable outrigger does not exceed the outer circumference of the flow guide liner and avoids interference between the outrigger and the reactor cavity wall when it is hoisted into the reactor cavity.

[0122] Subsequently, a lifting device 80 with level adjustment capability is installed on the top of the insulation layer module 13, and a large crawler crane 81 is used as the lifting equipment (the insulation layer module 13 can be transported from the assembly site to the lifting position by the large crawler crane 81, or it can be lifted directly by the large crawler crane 81 at the assembly site).

[0123] Before the formal hoisting, a trial hoisting is conducted: after the insulation module 13 is lifted away from the overall assembly platform 100, the hook is stopped and the machine is left to stand still for about 10 minutes. The condition of the crane, slings and equipment is checked and found to be normal. The levelness of the insulation module 13 is confirmed to be no more than 1 mm before the hoisting can continue.

[0124] Step S3: Overall hoisting of digital monitoring system

[0125] See Figure 22 and Figure 23 After the trial lifting was successful, the insulation module 13 was hoisted as a whole onto the reactor cavity 10 using a large crawler crane 81.

[0126] (1) Coarse centering of the bottom total station

[0127] See Figure 22 When the insulation module 13 is hoisted above the installation position of the stack cavity 10, the total station 70, which is pre-positioned at the bottom of the stack cavity 10, monitors the centering mark 74 (crosshair target) set at the bottom of the insulation module 13 to obtain the horizontal orientation deviation of the bottom of the insulation module 13 in real time. The orientation of the insulation module 13 is adjusted by the traction rope (not shown in the figure) so that the insulation module 13 is aligned in position and direction, and then the hook is slowly lowered.

[0128] (2) Upper laser tracker for precise monitoring

[0129] See Figure 23 When the bottom of the insulation module 13 approaches the upper entrance of the reactor cavity 10, fine-tuning monitoring is initiated: the displacement of the laser receiving target balls on each monitoring target pedestal 61 is measured by the laser tracker 60, and the gap between the insulation module 13 and the reactor cavity wall 11 is calculated and monitored in real time based on the virtual installation model to control the descent speed and orientation. After the insulation module 13 enters the upper entrance of the reactor cavity 10, the descent speed is controlled to be no greater than 0.3 m / min to ensure sufficient reaction time for fine-tuning the orientation. Simultaneously, changes in the hoisting load are monitored in real time. If the change in hoisting load instantaneously exceeds 1500 N, descent is immediately stopped, and hoisting can only continue after the cause has been identified and the problem eliminated.

[0130] In this embodiment, a dual-measurement device collaborative scheme is adopted, which uses a total station for coarse centering at the bottom and a laser tracker for fine monitoring at the top: the total station 70 performs rapid horizontal orientation centering before the insulation layer module 13 enters the cavity 10, and the laser tracker 60 performs high-precision gap quantification monitoring after the insulation layer module 13 enters the narrow cavity entrance.

[0131] This digital hoisting process based on laser tracker measurement technology can quantify and monitor the gap in real time at the predicted narrow location, ensuring the smooth progress of hoisting activities in narrow spaces and avoiding collision damage between the insulation module 13 and the reactor cavity wall 11.

[0132] However, it is understood that in other embodiments, the laser tracker 60 may be used to complete all centering and gap monitoring work, or other digital measuring devices capable of real-time three-dimensional coordinate measurement may be used to replace the laser tracker and total station. The present invention does not exclude these alternatives.

[0133] Step S4: Positioning and Fixture Removal

[0134] Once the lower vertical support 21 of the insulation layer module 13 is fully in place, the lower vertical support 21 is fixedly connected to the wall and / or bottom of the cavity 10 (e.g., by bolt connection or welding, the specific fixing method is determined according to the support structure design).

[0135] After the vertical support 21 is fixed, the lifting tools (lifting equipment 80, slings, etc.) are removed, as are the laser tracker measuring target 61 and the bottom monitoring device 71 (adjustable bracket 72 and centering mark 74) installed on the insulation module 13 for lifting monitoring. It should be noted that this step removes the tooling and equipment used for measurement and monitoring during the lifting process, not the load-bearing support structure of the insulation module 13 itself. That is, the insulation support 20 (including the lower vertical support 21, lower insulation support 22, middle insulation support 23, and insulation support limiting block 90) remains as a permanent component of the insulation module 13 within the cavity 10, continuing to support the insulation layer. This differs from solutions that require the removal of temporary auxiliary load-bearing tooling such as channel steel rings, connecting plates, adjusting plates, and jacks.

[0136] Step S5: Subsequent Installation

[0137] See Figure 24 After the insulation module 13 is in place and the monitoring fixtures are removed, the lower neutron shielding component 50 and other accessories are installed inside the reactor cavity 10. Then, the reactor pressure vessel 12 is hoisted into place, positioned within the insulation module 13 at a predetermined location, allowing it to rest on its supporting structure. At this point, the overall installation of the reactor pressure vessel's metal reflective insulation layer is complete.

[0138] In this embodiment, by adopting the process of external assembly and overall hoisting placement outside the nuclear island building, the on-site work for reactor cavity 10 only requires the installation of accessories such as the lower neutron shielding component 50, pre-hoisting site environment and path inspection, overall hoisting, and final placement, with an on-site operation time of approximately 20 days. In contrast, the traditional process of installing components layer by layer inside the reactor cavity typically requires 3 to 4 months for on-site assembly. Compared to this, the installation method in this embodiment significantly improves installation efficiency and drastically reduces the time occupied on the critical path of nuclear power plant construction.

[0139] In addition, the main structural components of the insulation layer include: See Figures 25 to 27 The diagram shows a partial structure of the main components of the insulation layer according to this embodiment. Figure 25 A partial structure of the thermal insulation layer combined support (thermal insulation layer bracket 20) is shown. The thermal insulation layer bracket 20 includes a lower thermal insulation layer support 22, a support connecting plate 24, a middle thermal insulation layer support 23, and a thermal insulation layer support limiting block 90. ​​The support components are connected by bolts to form a modular support system that can be flexibly combined into an overall module or partial modules according to assembly needs.

[0140] Figure 26 A partial structure of the insulation block 30 is shown. The insulation block 30 is a metal reflective insulation block, which is internally encapsulated with multiple polished stainless steel foil reflective sheets. Adjacent insulation blocks 30 are assembled by insulation block connecting buckles 33 to form a cylindrical insulation layer surrounding the reactor pressure vessel 12.

[0141] Figure 27 The partial structure of the insulation layer guide liner 40 is shown. The guide liner 40 is made of stainless steel sheet and is located inside the insulation block 30 (near the reactor pressure vessel 12). It is fixed to the insulation layer support 20 by the guide liner fixing bolts 43. On the one hand, it protects the insulation block 30, and on the other hand, it forms a cooling water annular cavity flow channel between itself and the outer wall of the reactor pressure vessel 12 under severe accident conditions, allowing water to flow and cool the outer wall of the reactor pressure vessel.

[0142] The specific structural forms of the aforementioned insulation layer support 20, insulation block 30, and flow guide liner 40 can be adjusted according to the design requirements of different reactor types (e.g., AP1000, Hualong One, CAP1400, etc.). This invention does not aim to... Figures 25 to 27 The specific structure shown is limited to this.

[0143] Although the various embodiments of the present invention have been described above with reference to various examples of the installation process of the metal reflective insulation layer of the reactor pressure vessel in a pressurized water reactor nuclear power plant, it should be understood that the embodiments within the scope of the present invention can be applied to the installation methods of other nuclear power equipment or industrial equipment with similar large annular structures that require high-precision overall positioning in confined spaces.

[0144] The foregoing description has already given many features and advantages, including various alternative implementations, as well as details of the structure and function of the apparatus and methods. This document is intended to be exemplary and is not exhaustive or limiting.

[0145] It will be apparent to those skilled in the art that various modifications can be made within the full scope indicated by the broad superordinate meaning of the terms expressed in the appended claims, particularly in terms of structure, materials, elements, components, shapes, dimensions, and arrangements of components, including combinations of these aspects within the scope of the principles described herein. Such various modifications are intended to be included herein, provided they do not depart from the spirit and scope of the appended claims.

[0146] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method for integrally installing a metal reflective insulation layer on a reactor pressure vessel, characterized in that, Includes the following steps: S1. Measure the walls, floor and outer surface of the reactor cavity and the reactor pressure vessel to obtain actual size data, and establish a virtual installation model based on the designed placement position of the reactor pressure vessel. S2. Outside the nuclear island plant, the insulation layer support, insulation block and flow guide plate are assembled into an insulation layer module. During the assembly process, the external dimension data of the insulation layer module is collected, and the external dimension data is imported into the virtual installation model for pre-installation verification. The assembly size is adjusted according to the verification results so that the distance between the flow guide plate and the outer wall of the reactor pressure vessel and the distance between the insulation layer module and the wall of the reactor cavity meet the installation requirements. S3. The qualified insulation layer module is hoisted into the reactor cavity as a whole. During the hoisting and descent, the position of the insulation layer module is measured in real time, and the gap between the insulation layer module and the wall of the reactor cavity is monitored in real time based on the virtual installation model. S4. Position and fix the insulation layer module in the stack cavity; S5. After the insulation layer module is in place and fixed, install the lower neutron shielding component, and then hoist the reactor pressure vessel into place inside the insulation layer module.

2. The overall installation method of the metal reflective insulation layer of the reactor pressure vessel as claimed in claim , characterized in that, The step S1 of arranging measurement points on the walls and ground of the reactor cavity and the outer surface of the reactor pressure vessel includes: evenly distributing measurement points at predetermined intervals along the height and horizontal directions on the steel walls of the reactor cavity; evenly distributing measurement points at predetermined intervals along the front-back and left-right directions on the ground of the reactor cavity; evenly distributing measurement points at predetermined intervals along the axial direction and at predetermined angles along the circumferential direction on the cylinder of the reactor pressure vessel; evenly distributing measurement points at predetermined angles along the circumferential direction on the nozzle of the reactor pressure vessel; and evenly distributing measurement points at predetermined angles along the circumferential direction on the outer surface of the flange of the reactor pressure vessel.

3. The overall installation method of the metal reflective insulation layer of the reactor pressure vessel as described in claim 1, characterized in that, In step S1, a laser tracker is used to collect data from measurement points arranged on the walls, ground, and outer surface of the reactor pressure vessel in the reactor cavity. The virtual installation model is established based on the centerline of the reactor pressure vessel after it is in place, the center elevation line of the nozzle, multiple position axes, and the levelness of the flange bearing surface.

4. The overall installation method of the metal reflective insulation layer of the reactor pressure vessel as described in claim 3, characterized in that, The allowable deviation of the nozzle center elevation line is ±1mm, the allowable deviation of the position axis is ±1mm, and the levelness of the flange bearing surface is less than or equal to 0.3mm.

5. The overall installation method of the metal reflective insulation layer of the reactor pressure vessel as described in claim 1, characterized in that, In step S1, the virtual installation model simulates: the assembly elevation and levelness of the insulation layer module; the positioning dimensions of the insulation layer module relative to the center line of the reactor pressure vessel; the distance between the flow guide liner and the outer wall of the reactor pressure vessel; and the distance between the limiting support working end face of the insulation layer bracket and the wall of the reactor cavity.

6. The overall installation method of the metal reflective insulation layer of the reactor pressure vessel as described in claim 1, characterized in that, Step S2 includes: S 21 A liftable operating platform is installed at the assembly site outside the nuclear island plant. S 22 1. Lay out the layout according to the positioning dimensions determined by the virtual installation model; S 23 The insulation layer support, the insulation block, and the flow guide plate are assembled into an integral insulation layer module, or they are assembled into multiple local modules in parallel in multiple layers and regions and then spliced ​​together to form an insulation layer module.

7. The overall installation method of the metal reflective insulation layer of the reactor pressure vessel as described in claim 6, characterized in that, In step S2, the insulation layer support adopts a combinable support structure, which can individually support the weight of one of the overall insulation layer modules or each of the local modules. The assembly process of the insulation layer bracket includes: first, installing and temporarily fixing the lower vertical support; installing the lower insulation layer support on the lower vertical support; assembling the lower insulation block and the lower flow guide plate on the lower insulation layer support to form the lower module; assembling each middle module layer by layer on the layered assembly platform; and then splicing each middle module with the lower module sequentially on the overall assembly platform.

8. The overall installation method of the metal reflective insulation layer of the reactor pressure vessel as described in claim 7, characterized in that, In step S2, for each assembled integral insulation layer module or partial module, dimensional data is collected, and the collected dimensional data is imported into the virtual installation model for pre-installation verification. The distance between the flow guide liner of the integral insulation layer module or the partial module and the outer wall of the reactor pressure vessel, as well as the distance between the limiting working end face of the insulation layer support limiting block and the wall of the reactor cavity, are checked to see if they meet the installation requirements. Only after passing the verification can the assembly of the next layer of integral insulation layer module or partial module proceed.

9. The overall installation method of the metal reflective insulation layer of the reactor pressure vessel as described in claim 8, characterized in that, In step S2, the arrangement of measurement points for collecting external dimension data includes: evenly distributing measurement points every 90° along the circumference on the lower vertical support; evenly distributing measurement points along the axial direction at predetermined intervals and along the circumference at predetermined angles on the outer surface of the flow guide liner; setting measurement points at the four corners and center of the limiting working end face of the insulation layer support limiting block; and using a laser tracker to collect data from each measurement point.

10. The overall installation method of the metal reflective insulation layer of the reactor pressure vessel as described in claim 7, characterized in that, As described in step S2, the installation deviation requirements include: When the lower insulation layer is installed, its elevation deviation is ±1mm, its levelness is no more than 1mm, and its distance deviation from the center line of the reactor pressure vessel is ±1mm. After the insulation blocks are assembled, the gap between adjacent insulation blocks shall not exceed 2mm, and the allowable deviation of the inner circle radius formed by the insulation blocks shall be ±2mm. After the flow guide liner is installed, the allowable deviation between the flow guide liner and the center line of the reactor pressure vessel is ±1mm. During pre-installation verification, the allowable deviation of the distance between the limiting working end face of the insulation layer support limiting block and the wall of the reactor cavity is ±1mm. The allowable deviation between the flow guide liner and the outer wall of the reactor pressure vessel is ±1mm.

11. The overall installation method of the metal reflective insulation layer of the reactor pressure vessel as described in claim 1, characterized in that, In step S3, the qualified insulation layer module is transported to the reactor cavity via a large crawler crane or directly hoisted. During hoisting, a lifting device with leveling adjustment capability is used to connect to the top of the insulation layer module.

12. The overall installation method of the metal reflective insulation layer of the reactor pressure vessel as described in claim 1, characterized in that, In step S3, when the insulation layer module is hoisted above the installation position of the reactor cavity, the following centering operation is performed: The centering mark on the monitoring device located at the bottom of the insulation layer module is monitored by a total station located at the bottom of the cavity. The position of the insulation module is adjusted by the traction rope, and the module is then slowly lowered into the hook after being aligned in position and direction.

13. The overall installation method of the metal reflective insulation layer of the reactor pressure vessel as described in claim 12, characterized in that, After assembly in step S2, the monitoring device is installed below the bottom guide plate of the insulation layer module. The installation and adjustment of the monitoring device includes the following steps: A monitoring device is provided, including an adjustable bracket and an alignment mark, wherein the alignment mark is disposed on the base of the adjustable bracket and the adjustable bracket has multiple adjustable legs; The adjustable bracket is initially installed at the bottom of the lower guide plate; Adjust the length of each of the adjustable legs so that the center of the centering mark coincides with the center line of the reactor pressure vessel laid out on the assembly platform; When the overlap deviation is less than or equal to 0.3 mm, fix each of the adjustable legs.

14. The overall installation method of the metal reflective insulation layer of the reactor pressure vessel as described in claim 1, characterized in that, In step S3, a multi-layer laser tracker monitoring target is arranged on the outside of the lower flow guide liner of the insulation layer module. When the bottom of the insulation layer module approaches the upper inlet of the reactor cavity, the laser tracker measures the displacement of the laser receiving target ball on each monitoring target and monitors the gap between the insulation layer module and the wall of the reactor cavity in real time based on the virtual installation model to control the descent.

15. The overall installation method of the metal reflective insulation layer of the reactor pressure vessel as described in claim 14, characterized in that, Step S3 also includes the following monitoring operations: The laser tracker monitoring target base is provided with at least three layers along the outer side of the lower guide liner, with multiple monitoring target bases evenly distributed in each layer along the circumference. When the insulation layer module enters the upper inlet of the stack cavity, its descent speed is less than 0.3 m / min; Monitor changes in the hoisting load in real time. When the change in the hoisting load exceeds the predetermined threshold, stop the descent immediately and investigate the cause.

16. The overall installation method of the metal reflective insulation layer of the reactor pressure vessel as described in claim 1, characterized in that, In step S4, after the vertical support of the insulation layer module is fully in place, the vertical support is fixedly connected to the cavity wall and / or bottom.

17. The integral installation method of the metal reflective insulation layer of the reactor pressure vessel as described in claim 16, characterized in that, After the vertical support is fixed, remove the hoisting tools, and remove the laser tracker measuring target and bottom monitoring device installed on the insulation layer module for hoisting monitoring.

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