Method and system for shortening construction process of pebble bed type high-temperature gas cooling initial core

Abstract

To provide a method and a system for shortening a construction process of a pebble bed type high-temperature gas cooling initial core.SOLUTION: A method and a system for shortening a construction process of a pebble bed type high-temperature gas cooling initial core include: constructing a physical calculation model of an initial loading and the construction process of the initial core on the basis of a material and a structural parameter of each aggregate; selecting a combustible poison addition scheme which can be executed by using a physical calculation model by adding a combustible poison to at least one of a black lead sphere and a fuel element; and evaluating safety of the initial loading and the construction process of the initial core regarding the realizable combustible poison addition scheme and selecting the optimum combustible poison addition scheme on the basis of the result of the safety evaluation. An amount of the black lead sphere is reduced, an operation output level in the initial core construction step is increased, and time of constructing the initial core is reduced so that economy of the pebble bed type high-temperature gas cooling core is significantly reduced.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to the technical field of nuclear reactor core fuel management and operation, and more particularly to a method and system for shortening the construction process of a pebble bed type high temperature gas cooled initial core. [Background technology]

[0002] The fuel elements in a pebble bed high-temperature gas-cooled reactor are different from the fuel assemblies in conventional pressurized water reactors; they are generally spherical elements with a diameter of 6 cm, and tens to hundreds of thousands of such fuel elements are arranged throughout the core.

[0003] The fuel loading process of the pebble bed type high-temperature gas-cooled reactor is different from that of the pressurized water reactor, which loads the fuel assemblies into the entire core at one time. In contrast, the pebble bed type high-temperature gas-cooled reactor first loads a certain height of pure graphite balls (the outer shape is the same as the fuel elements and does not contain uranium) layer in the lower part of the core, and then loads a certain height of mixed fuel (fuel elements and graphite balls mixed in a certain ratio) on top of the graphite ball laying layer to reach the initial full loading height and complete the initial loading. After the initial loading, the construction of the initial loading core is started, that is, the reactor is operated at a certain power, and the mixed fuel continues to be loaded into the core at the initial full loading height, and the mixed fuel reaches the full height of the active part, and then the graphite balls in the pure graphite ball laying layer are gradually removed, and at the same time, the same amount of mixed fuel is added to the upper part of the core, and thus the height of the pure graphite ball laying layer is gradually decreased and the height of the mixed fuel is gradually increased until the entire active part is completely composed of mixed fuel, completing the construction of the initial loading core.

[0004] Therefore, the construction process of the initial core can be described as the process of adding mixed fuel to the initial full loading height up to the active part height, and removing the pure graphite ball layer to realize the full mixed fuel loading in the active part of the core. In the construction process of the initial core, the number of fuel elements in the core is small, the excess reactivity of the reactor is low, and the operating power of the reactor is low due to the power limit of each fuel element, so the main time is spent on removing the pure graphite ball layer, which often takes several months. Therefore, if the height of the graphite ball layer can be lowered or the loading height / amount of mixed fuel can be increased during the initial full loading, the time of the initial core construction can be shortened (the number of graphite balls in the pure graphite ball layer is reduced and the removal time is shortened). In addition, when increasing the amount of mixed fuel loaded into the initial core, the average power of each fuel element can be reduced by increasing the number of fuel elements, and the operating power of the reactor can be appropriately increased during the construction process of the initial core, thereby increasing the graphite ball removal speed and further shortening the construction time of the initial core. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments. In this section, the Abstract of the Application, and the Title of the Invention, simplifications or omissions may be made to avoid obscuring the purpose, and such simplifications or omissions shall not be used to limit the scope of the present invention.

[0006] The present invention has been proposed in view of the above problems.

[0007] A first aspect of an embodiment of the present invention provides a method for shortening a construction process of a pebble bed type high temperature gas cooled initial core, comprising: constructing a physical calculation model of the construction process of the initial loading and initial loading core of a pebble bed type high temperature gas cooled reactor based on material and structural parameters of each assembly; adding burnable poison to graphite balls, fuel elements or both, and selecting a feasible burnable poison addition scheme using the physical calculation model; performing a safety evaluation of the construction process of the initial loading and initial loading core for the feasible burnable poison addition schemes, and selecting an optimal burnable poison addition scheme based on a result of the safety evaluation.

[0008] In a preferred embodiment of the method for shortening the construction process of a pebble bed type high temperature gas cooled initial core described in the present invention, the material and structural parameters of each assembly include the diameter and height of the core, the loading and enrichment of the fuel elements, and the material and structural parameters of the control rods, absorber balls, graphite inner core members, carbon inner core members, and metal inner core members.

[0009] In a preferred embodiment of the method for shortening the construction process of the pebble bed type high temperature gas cooled initial core described in the present invention, the construction of the physical calculation model includes: Dividing the active region of the core into a plurality of linear channels having equal cross-sectional areas in a radial direction, and stacking the linear channels in an axial direction from the center to the edges; Divide the entire reactor into multiple "spectral zones" of equal volume as the basic unit of energy spectrum calculation and fuel cycle simulation, and flow the graphite ball laying layer and mixed fuel element from top to bottom in the axial direction layer by layer, assuming that there is no cross flow between the linear flow paths in the radial direction, to realize the simulation of core ball flow and the construction of a physical calculation model; After the physical calculation model is constructed, the effects of the mixed-sphere ratio, operating power, primary circuit flow rate, fuel element enrichment, and cycle number on the safety parameters of the core are evaluated based on the calculation data, sensitivity parameters are obtained, and a feasible burnable poison addition scheme is selected based on the sensitivity coefficients.

[0010] In a preferred embodiment of the method for shortening the construction process of the pebble bed type high temperature gas cooled initial core described in the present invention, the selection of the burnable poisoning scheme is: Considering that the graphite balls are directly taken out of the core in the initial core construction process, and the impact on the subsequent reactor operation is much smaller than that of the fuel elements, it is preferable to add burnable poison to the graphite balls, and add burnable poison to the fuel elements and both according to the specific physical calculation results and operation requirements; Increasing the initial total mixed fuel loading amount of the pebble bed type high temperature gas-cooled reactor and reducing the height of the pure graphite ball laying layer to shorten the construction time of the initial core, i.e., introducing a certain negative reactivity into the original core loading by adding burnable poison to reduce excess reactivity, thereby increasing the initial total mixed fuel loading amount of the pebble bed type high temperature gas-cooled reactor; The calculation of the negative reactivity of the burnable poison is TIFF2025019018000002.tif7170, where TIFF2025019018000003.tif6170 is the fast neutron multiplication factor, TIFF2025019018000004.tif7170 is the probability of escape resonance absorption, TIFF2025019018000005.tif7170 is the thermal neutron utilization factor, TIFF2025019018000006.tif7170 is the effective fission neutron number, TIFF2025019018000007.tif7170 is the deceleration non-leakage probability, TIFF2025019018000008.tif7170 shows the diffusion non-leakage probability, When the fuel mixture loading is constant, adding a burnable poison to the core will cause the burnable poison to absorb some of the neutrons, increasing the proportion of all absorbed thermal neutrons, thus decreasing the thermal neutron utilization factor and decreasing the core reactivity, as follows: TIFF2025019018000009.tif14170, where TIFF2025019018000010.tif7170 shows the reactivity of the core.

[0011] As a preferred embodiment of the method for shortening the construction process of the pebble bed type high temperature gas cooled initial core described in the present invention, The amount of the burnable poison added should not be too much or too little. If it is too much, even if the active part of the core is loaded with a full load of mixed fuel, criticality cannot be achieved. If it is too little, the effect of increasing the amount of mixed fuel loaded is limited. That is, the method further includes calculating using the physical calculation model and selecting an appropriate loading amount.

[0012] In a preferred embodiment of the method for shortening the construction process of a pebble bed type high temperature gas cooled initial core described in the present invention, the safety assessment of the process includes: For each selected burnable poisoning scheme, conducting a safety assessment of the initial loading and initial core construction process to verify that the entire process of said burnable poisoning scheme meets the requirements of the safety parameters specified in the reactor safety analysis report and does not exceed safety limits under any operating conditions; The safety parameters specified in the Reactor Safety Analysis Report include the reactor primary circuit pressure, maximum fuel element temperature, maximum single-ball power, inlet and outlet temperatures, and maximum discharge burnup.

[0013] In a preferred embodiment of the method for shortening the construction process of a pebble bed type high temperature gas cooled initial core described in the present invention, the selection of the optimal burnable poison addition scheme comprises: This involves determining the optimal burnable poison addition scheme from among feasible burnable poison addition schemes that have passed safety assessment, taking into consideration fuel economy, safety margins, construction time for the initial core, reactor operating power level, and loading and unloading rates.

[0014] A second aspect of an embodiment of the present invention provides a system for shortening a process for constructing a pebble bed type high temperature gas cooled initial core, comprising: a model construction unit used to construct a physical calculation model of the initial loading and initial core construction process of the pebble bed high-temperature gas-cooled reactor based on the material and structural parameters of each assembly; an addition scheme selection unit used to add burnable poisons to the graphite balls, the fuel elements, or both, and to select a feasible burnable poison addition scheme using said physics-based computational model; and an evaluation and selection unit that is used to perform a safety evaluation of the initial loading and initial core construction process for the feasible burnable poison addition schemes, and to select an optimal burnable poison addition scheme based on a result of the safety evaluation.

[0015] A third aspect of an embodiment of the present invention provides an apparatus, the apparatus comprising: A processor; a memory for storing processor-executable instructions; The processor is configured to invoke instructions stored in the memory to perform the method according to any one of the embodiments of the present invention.

[0016] A fourth aspect of the present invention provides a computer readable storage medium having computer program instructions stored thereon, comprising: The computer program instructions, when executed by a processor, implement the method according to any one of the embodiments of the present invention.

[0017] The beneficial effects of the present invention are as follows: The method and system for shortening the construction process of the pebble bed type high temperature gas-cooled initial core provided by the present invention reduces the height of the graphite ball laying layer, i.e., reduces the amount of graphite balls, thereby greatly reducing the procurement cost of graphite balls, saving the investment in the power plant and improving the economy; at the same time, it reduces the demand for graphite balls, reduces the number of graphite balls taken out from the initial core, greatly shortens the construction time of the initial core; furthermore, the present invention increases the loading amount of the mixed fuel in the initial full loading, increases the power level of the initial reactor construction process, increases the loading and unloading speed, further reduces the construction time of the initial core, shortens the commissioning period of the power plant, and greatly improves the economy of the pebble bed type high temperature gas-cooled reactor. [Brief description of the drawings]

[0018] In order to more clearly describe the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings used in the description of the embodiments, and it should be understood that the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative efforts. [Figure 1] 1 shows an overall flow chart of a method and system for shortening the construction process of a pebble bed type high temperature gas cooled initial core provided by the present invention. [Diagram 2] FIG. 1 is a schematic diagram showing the structure of a fuel element of a pebble bed high temperature gas-cooled reactor in accordance with the method and system for shortening the construction process of a pebble bed high temperature gas-cooled initial core provided by the present invention. [Diagram 3] 1 is a schematic diagram showing the loading section of the active part of an initial load of a pebble bed type high temperature gas-cooled reactor in accordance with a method and system for shortening the construction process of a pebble bed type high temperature gas-cooled initial core provided by the present invention; FIG. [Figure 4] 1 is a schematic diagram showing an initial full loading of a pebble bed high temperature gas-cooled reactor in accordance with a method and system for shortening the construction process of a pebble bed high temperature gas-cooled initial core provided by the present invention; FIG. [Diagram 5]FIG. 2 is a schematic diagram showing changes in core loading during initial core construction of a pebble bed type high temperature gas-cooled reactor in accordance with the method and system for shortening the construction process of a pebble bed type high temperature gas-cooled initial core provided by the present invention. [Figure 6] 1 is a schematic diagram showing the initial core loading of a pebble bed type high temperature gas-cooled reactor according to the method and system for shortening the construction process of a pebble bed type high temperature gas-cooled initial core provided by the present invention; FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] In order to make the above objects, features and advantages of the present invention clearer and easier to understand, the following describes in detail specific embodiments of the present invention in conjunction with the accompanying drawings of the specification, but it is clear that the described embodiments are only a part of the embodiments of the present invention, and are not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without requiring creative efforts shall be within the protection scope of the present invention.

[0020] In order to facilitate a thorough understanding of the present invention, numerous specific details are set forth below; however, the present invention may be embodied in other ways than those described herein, and similar extensions may be made by those skilled in the art without departing from the spirit of the present invention, and therefore the present invention is not limited by the specific examples disclosed below.

[0021] Also, as used herein, "one embodiment" or "embodiment" refers to a particular feature, structure, or characteristic that may be included in at least one embodiment of the present invention. The appearances of the phrase "in one embodiment" in different places in this specification are not all referring to the same embodiment, nor are they mutually exclusive embodiments separate or in the alternative from other embodiments.

[0022] The present invention will be described in detail with schematic diagrams, and in describing the embodiments of the present invention in detail, in order to facilitate the description, the cross-sectional diagrams showing the structure of the device are partially enlarged and not according to the normal scale, and the schematic diagrams are merely illustrative and do not limit the scope of protection of the present invention, and should include the three-dimensional spatial dimensions of length, width and depth during actual production.

[0023] Also, in the description of the present invention, as explained, terms such as "upper, lower, inner, outer" indicate orientations or positional relationships based on those shown in the accompanying drawings and are intended only to facilitate and simplify the description of the present invention, and do not dictate or suggest that the referred devices or elements have a particular orientation and must be constructed and operated in a particular orientation, and therefore should not be understood as limitations of the present invention. Furthermore, the terms "first, second or third" are for descriptive purposes only and should not be understood as dictating or suggesting relative importance.

[0024] In the present invention, the terms "attach, connect, and couple" should be understood in a broad sense unless otherwise specified or limited, and may be fixedly connected, detachably connected, or integrally connected, mechanically connected, electrically connected, directly connected, indirectly connected via an intermediate medium, or internally communicated between the two members. Those skilled in the art can understand the specific meaning of the above terms in the present application according to the actual situation.

[0025] Example 1 Referring to Figures 1 to 6, an embodiment of the present invention provides a method for shortening the construction process of a pebble bed type high temperature gas cooled initial core, and the fuel elements of a pebble bed type high temperature gas cooled reactor are generally spherical elements with a diameter of 6 cm (see Figure 2), which are different from the fuel assemblies of conventional pressurized water reactors, and tens of thousands to hundreds of thousands of such fuel elements are arranged throughout the core, and schematic diagrams of the core loading and construction process of the initial core of a pebble bed type high temperature gas cooled reactor are shown in Figures 3 to 6. For this purpose, a method is proposed to increase the amount of mixed fuel loaded in the initial full load of a pebble bed type high temperature gas cooled reactor and shorten the construction process of the initial core, so as to achieve a reduction in the amount of graphite balls, and at the same time, increase the operating power level in the initial core construction stage, shorten the construction time of the initial core, and greatly improve the economic efficiency of the pebble bed type high temperature gas cooled reactor. Specific steps include the following S1 to S3.

[0026] S1: Based on the material and structural parameters of each assembly, a physical calculation model is constructed for the initial loading and construction process of the initial core of the pebble bed type high temperature gas-cooled reactor. The material and construction parameters of each assembly include the diameter and height of the core, the fuel element loading and enrichment, and the material and construction parameters of the control rods, absorber spheres, graphite internals, carbon internals, and metallic internals.

[0027] In addition, the initial loading and initial core construction process of the pebble bed type high temperature gas-cooled reactor is different from that of the pressurized water reactor, there are different loading areas such as graphite ball laying layer and mixed fuel in the core, and the height of different loading areas gradually changes (as shown in Figures 3 to 6), and the whole process is very complicated, so it is necessary to build an accurate physical calculation model to analyze and calculate the whole process.

[0028] As explained, building a physical computational model involves: Dividing the active region of the core into a plurality of linear channels having equal cross-sectional areas in a radial direction, and stacking the linear channels in an axial direction from the center to the edges; The entire reactor is divided into multiple "spectral zones" of equal volume as the basic unit for energy spectrum calculation and fuel cycle simulation. The graphite ball laying layer and mixed fuel elements are made to flow layer by layer from top to bottom in the axial direction, and it is assumed that there is no cross flow between the linear flow paths in the radial direction, and the simulation of the core ball flow and the construction of a physical calculation model are realized. After the physical calculation model is constructed, the effects of the mixed-sphere ratio, operating power, primary circuit flow rate, fuel element enrichment, and cycle number on the safety parameters of the core are evaluated based on the calculation data, sensitivity parameters are obtained, and a feasible burnable poison addition scheme is selected based on the sensitivity coefficients.

[0029] S2: Add burnable poison to the graphite balls, fuel elements, or both, and use a physics model to select a feasible burnable poisoning scheme. In the case of a pebble-bed high-temperature gas-cooled reactor, all fuel elements loaded at the initial loading are new, so there is no fissile poison, and the loading amount required to achieve criticality is small. Combined with the safety requirement of the shutdown margin, the mixed fuel loading at the initial full loading is only a part of the active part of the reactor (see Figure 4), and a pure graphite ball layer needs to be added at the bottom. If the graphite ball layer is high, it takes a long time to remove all the graphite balls in it, that is, the construction time of the initial core is long. Therefore, by increasing the amount of mixed fuel loading at the initial full loading of a pebble-bed high-temperature gas-cooled reactor and reducing the height of the pure graphite ball layer, the construction time of the initial core can be shortened.

[0030] The pebble bed high-temperature gas-cooled reactors being built in China, whether HTR-10 or HTR-PM, do not use burnable poisons. Burnable poisons play a role in counteracting most of the excess reactivity contained in the initial reactor charge. Intuitively, for pebble bed high-temperature gas-cooled reactors, adding burnable poisons introduces a certain negative reactivity into the original core charge, reducing the excess reactivity, and thereby increasing the mixed fuel load of the initial full charge.

[0031] Specifically, the calculation of the negative reactivity of a burnable poison is as follows: TIFF2025019018000011.tif7170, where TIFF2025019018000012.tif6170 is the fast neutron multiplication factor, TIFF2025019018000013.tif7170 is the probability of escape resonance absorption, TIFF2025019018000014.tif7170 is the thermal neutron utilization factor, TIFF2025019018000015.tif7170 is the effective fission neutron number, TIFF2025019018000016.tif7170 is the deceleration non-leakage probability, TIFF2025019018000017.tif7170 shows the diffusion non-leakage probability, When the fuel mixture loading is constant, adding a burnable poison to the core will cause the burnable poison to absorb some of the neutrons, increasing the proportion of all absorbed thermal neutrons, thus decreasing the thermal neutron utilization factor and decreasing the core reactivity, as follows: TIFF2025019018000018.tif14170, where TIFF2025019018000019.tif7170 shows the reactivity of the core, It is physically possible in the reactor to add burnable poisons to the graphite balls or fuel elements, or both. Adding burnable poisons to the graphite balls is preferable, considering that the graphite balls are taken directly from the core during the initial core construction process (and may be partially reintroduced into the reactor for cycling), and therefore have a much smaller impact on the subsequent reactor operation than the fuel elements (which generally pass through the core multiple times), and the penalty of the burnable poisons can be avoided or minimized. Of course, burnable poisons can also be added to the fuel elements or both, depending on the specific physical calculation results and operational requirements.

[0032] Furthermore, the amount of burnable poison added cannot be too much or too little; if it is too much, criticality will not occur even if the active part of the core is fully loaded with mixed fuel, and if it is too little, the effect of increasing the amount of mixed fuel loaded is limited; in other words, the appropriate loading amount is selected by calculation using a physical calculation model.

[0033] S3: For feasible burnable poisoning schemes, a safety assessment is carried out for the initial loading and the initial core construction process, and the optimal burnable poisoning scheme is selected based on the results of the safety assessment. The process safety assessment is carried out as follows: For each selected burnable poisoning scheme, conducting a safety assessment of the initial loading and initial core construction process to ensure that the entire process of the burnable poisoning scheme meets the requirements of the safety parameters specified in the reactor safety analysis report and does not exceed safety limits under any operating conditions; Safety parameters specified in the Reactor Safety Analysis Report include the reactor primary circuit pressure, maximum fuel element temperature, maximum single-ball power, inlet and outlet temperatures, and maximum discharge burnup.

[0034] Furthermore, the selection of the optimal burnable poisoning scheme is This involves determining the optimal burnable poison addition scheme from among feasible burnable poison addition schemes that have passed safety assessment, taking into consideration fuel economy, safety margins, construction time for the initial core, reactor operating power level, and loading and unloading rates.

[0035] As described, the method and system for shortening the construction process of a pebble bed type high temperature gas-cooled initial core provided by the present invention reduces the height of the graphite ball laying layer, i.e., reduces the amount of graphite balls, thereby significantly reducing the procurement cost of graphite balls, saving investment in the power plant and improving the economy; at the same time, it reduces the demand for graphite balls and reduces the number of graphite balls removed from the initial core, significantly shortening the construction time of the initial core; further, the present invention increases the loading amount of the initial full loading mixed fuel, increases the power level of the initial reactor construction process, increases the loading and unloading speed, further shortens the construction time of the initial core, shortens the commissioning period of the power plant, and significantly improves the economy of the pebble bed type high temperature gas-cooled reactor.

[0036] The second aspect disclosed in the present invention is To provide a system for shortening the construction process of a pebble bed type high temperature gas cooled initial core, a model construction unit used to construct a physical calculation model of the initial loading and initial core construction process of the pebble bed high-temperature gas-cooled reactor based on the material and structural parameters of each assembly; an addition scheme selection unit used to add burnable poisons to the graphite spheres, the fuel elements, or both, and to select a feasible burnable poison addition scheme using a physics computation model; and an evaluation and selection unit which is used to perform a safety assessment of the initial loading and initial core construction process for feasible burnable poisoning schemes, and to select the optimal burnable poisoning scheme based on the results of the safety assessment.

[0037] The third aspect disclosed in the present invention is Providing facilities, A processor; a memory for storing processor-executable instructions; Here, the processor is configured to invoke instructions stored in the memory to perform any one of the methods described above.

[0038] The fourth aspect disclosed in the present invention is providing a computer readable storage medium having computer program instructions stored thereon; The computer program instructions, when executed by a processor, implement any one of the methods described above.

[0039] The present invention may be a method, an apparatus, a system and / or a computer program product, and the computer program product may include a computer-readable storage medium having computer-readable program instructions stored thereon for carrying out aspects of the present invention.

[0040] A computer readable storage medium may be a tangible facility capable of holding and storing instructions for use by an instruction execution facility. A computer readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination thereof. More specific examples (non-exhaustive list) of computer readable storage media include portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disk read-only memory (CD-ROM), digital versatile disk (DVD), memory stick, floppy disk, mechanical encoding device, punch card or ridge-in-groove structure on which instructions are stored, and any suitable combination of the foregoing. As used herein, computer-readable storage media is not to be construed as ephemeral signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted over electrical wires.

[0041] Example 2 The present embodiment differs from the first embodiment in that it provides a verification test of a method and system for shortening the construction process of a pebble bed type high temperature gas cooled initial core in order to verify and explain the technical effects used in the present method.

[0042] In this example, we take the demonstration project HTR-PM of a high-temperature gas-cooled reactor nuclear power plant as an example. The pure graphite spheres layer at the bottom of the core before the initial loading is about 6m thick, and the number of pure graphite spheres is about 240,000. The construction of the initial core involves gradually removing these 240,000 graphite spheres and replacing them with the same number of mixed fuel. The removal capacity of the HTR-PM fuel loading and removal system is 6,000 elements / day, so the time required to complete the initial core loading is about 240,000 / 6,000=40 days.

[0043] If the amount of mixed fuel loaded in the initial reactor is increased and the amount of pure graphite balls loaded is correspondingly decreased, the construction time of the initial core can be significantly shortened. For example, if the amount of mixed fuel loaded is increased by 120,000 pieces, the construction time can be shortened by 120,000 / 6000=20 days, which has considerable benefits in terms of schedule and economy. Therefore, the method provided by the present invention reduces the height of the graphite ball laying layer, i.e., reduces the amount of graphite balls, thereby significantly reducing the procurement cost of graphite balls, saving investment in the power plant and improving the economy, and at the same time, reducing the demand for graphite balls and reducing the number of graphite balls taken out from the initial core, significantly shortening the construction time of the initial core. Furthermore, the present invention increases the amount of mixed fuel loaded in the initial full load, increasing the power level of the initial reactor construction process, increasing the loading and unloading speed, further reducing the construction time of the initial core, shortening the commissioning period of the power plant, and significantly improving the economy of the pebble bed type high temperature gas-cooled reactor.

[0044] It should be noted that the above-mentioned embodiments are merely for illustrating the technical solutions of the present invention, and are not intended to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art may make modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and such modifications or substitutions should be included in the scope of the claims of the present invention.

Claims

1. Building a physical calculation model of the initial loading and initial core construction process of a pebble bed high-temperature gas-cooled reactor based on the material and structural parameters of each assembly; adding burnable poisons to the graphite spheres, the fuel elements, or both, and using said physics-based model to select a viable burnable poisoning scheme; performing a safety assessment of the initial loading and the initial core construction process for the feasible burnable poison addition schemes, and selecting an optimal burnable poison addition scheme based on a result of the safety assessment.

2. The method for shortening the construction process of a pebble bed type high temperature gas-cooled initial core as described in claim 1, characterized in that the material and structural parameters of each assembly include the diameter and height of the core, the loading amount and enrichment of fuel elements, and the material and structural parameters of control rods, absorber balls, graphite inner core members, carbon inner core members, and metal inner core members.

3. The construction of the physical calculation model includes: Dividing the active region of the core into a plurality of linear channels having equal cross-sectional areas in a radial direction, the linear channels being stacked in an axial direction from the center to the edges; Divide the entire reactor into multiple "spectral zones" of equal volume, and use them as the basic units for energy spectrum calculation and fuel cycle simulation. Flow the graphite ball laying layer and mixed fuel element layer by layer from top to bottom in the axial direction, and assume that there is no cross flow between the linear flow paths in the radial direction. Realize the simulation of core ball flow and the construction of a physical calculation model; The method for shortening the construction process of a pebble bed type high temperature gas-cooled initial loading core according to claim 2, characterized in that after the physical calculation model is constructed, the method includes: evaluating the influence of the mixed ball ratio, the operating power, the primary circuit flow rate, the enrichment of the fuel element, and the number of cycles on the safety parameters of the core based on the calculation data, obtaining sensitivity parameters, and selecting a feasible burnable poison addition scheme based on the sensitivity coefficients.

4. The selection of the burnable poisoning scheme comprises: Considering that the graphite balls are directly taken from the core in the initial core construction process, and the impact on the subsequent reactor operation is much smaller than that of the fuel elements, it is preferable to add burnable poison to the graphite balls, and add burnable poison to the fuel elements and both according to the specific physical calculation results and operation requirements; Increasing the initial total mixed fuel loading amount of the pebble bed high temperature gas-cooled reactor and reducing the height of the pure graphite ball laying layer to shorten the construction time of the initial core, i.e., introducing a certain negative reactivity into the original core loading by adding burnable poison to reduce the excess reactivity, thereby increasing the initial total mixed fuel loading amount of the pebble bed high temperature gas-cooled reactor; The calculation of the negative reactivity of the burnable poison is Where: is the fast neutron multiplication factor, is the probability of escape resonance absorption, is the thermal neutron utilization factor, is the effective fission neutron number, is the deceleration non-leakage probability, denotes the diffusion non-leakage probability, When the fuel mixture loading is constant, adding a burnable poison to the core will cause the burnable poison to absorb some of the neutrons, increasing the proportion of all absorbed thermal neutrons, thus decreasing the thermal neutron utilization factor and decreasing the core reactivity, as follows: Where: The method for shortening the construction process of a pebble bed type high temperature gas cooled initial core according to claim 3, wherein: ##EQU1## indicates the reactivity of the core.

5. The method for shortening the construction process of a pebble bed type high temperature gas cooled initial loading core as described in claim 4, characterized in that if the amount of burnable poison added is too large, criticality cannot be achieved even if the active part of the core is fully loaded with mixed fuel, and if the amount of burnable poison added is too small, the effect of increasing the amount of mixed fuel loaded is limited, i.e., the method further includes calculating using the physical calculation model to select an appropriate loading amount.

6. The safety assessment of the process includes: For each selected burnable poisoning scheme, conducting a safety assessment of the initial loading and initial core construction process to verify that the entire process of said burnable poisoning scheme meets the requirements of the safety parameters specified in the reactor safety analysis report and does not exceed safety limits under any operating conditions; The method for shortening the construction process of a pebble bed type high temperature gas cooled initial core as described in claim 5, characterized in that the safety parameters specified in the reactor safety analysis report include the reactor primary circuit pressure, the maximum temperature of the fuel elements, the maximum single-sphere power, the inlet and outlet temperatures and the maximum unloaded burnup.

7. The selection of the optimal burnable poisoning scheme comprises:

7. The method for shortening the construction process of a pebble bed type high temperature gas cooled initial core as described in claim 6, characterized in that it includes determining an optimal burnable poison addition scheme by comprehensively taking into consideration fuel economy, safety margin, construction time of the initial core, operating power level of the reactor, and loading / unloading speed for feasible burnable poison addition schemes that have passed safety evaluation.

8. a model construction unit used to construct a physical calculation model of the initial loading and initial core construction process of the pebble bed high-temperature gas-cooled reactor based on the material and structural parameters of each assembly; an addition scheme selection unit used to add burnable poisons to the graphite balls, the fuel elements, or both, and to select a feasible burnable poison addition scheme using said physics-based computational model; and an evaluation and selection unit that is used to perform a safety evaluation of the initial loading and the initial core construction process for the feasible burnable poison addition schemes, and to select an optimal burnable poison addition scheme based on a result of the safety evaluation.

9. A facility comprising: A processor; a memory for storing processor-executable instructions; Said facility, characterized in that said processor is arranged to call instructions stored in said memory and to carry out the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having stored thereon computer program instructions which, when executed by a processor, implement the method according to any one of claims 1 to 7.

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