Method for judging the feasibility of core loading sequence for pressurized water reactor nuclear power plant

Abstract

The present invention discloses a method for determining the feasibility of a core loading sequence for a pressurized water reactor nuclear power unit, comprising the following steps: first, sorting all core physical locations from smallest to largest according to the loading sequence; establishing a nine-square grid coordinate system, taking each fuel assembly location to be determined as the center Mid of the nine-square grid coordinate system, and marking its orientation; marking the corresponding core physical locations in the order of arrangement, calling a related function (RelatedFunction) after each marking to update the associated nine-square grid coordinate system, and using different assignments to distinguish new and old fuel assemblies; after calling the related function (RelatedFunction) at each step, immediately calling a loading feasibility determination function (EstimateFunction); and continuing to determine the position E2 in step 84. If loading difficulties exist, marking the position and proceeding to the next step; otherwise, directly proceeding to the next step. This method automatically determines the location of fuel assemblies that are difficult to load, thereby eliminating the problem of manually adjusting and verifying the loading sequence one by one.

Description

Technical Field

[0001] The invention belongs to a core fuel management method for a pressurized water reactor nuclear power plant, and in particular relates to a method for judging the feasibility of a core loading sequence of a pressurized water reactor nuclear power unit. Background Art

[0002] Currently, the third generation AFA-3G fuel assembly is a core fuel used in pressurized water reactor nuclear power plants. After the core undergoes a chain fission reaction, the fuel assembly deforms under the action of various forces and deviates from its normal vertical state. There are many types of component deformation, such as Figure 1 shown.

[0003] Normally, component deformation does not cause problems in the operation of nuclear power plants, but it will cause difficulties in loading fuel assemblies into the core. The gap between fuel assemblies in a pressurized water reactor is 1mm, and the gap between fuel assemblies becomes even smaller due to irradiation growth of the grid. During loading, since the spatial position of the core is fixed, after the fuel assembly is deformed, the positioning pins on the grid plate under the core may not be able to smoothly enter the positioning holes of the lower tube seat of the fuel assembly. Figure 2 As shown, this can make loading the fuel assembly itself or its adjacent fuel assemblies into the core difficult, requiring repeated attempts and adjustments to position the fuel assembly. Deformation can be particularly detrimental in the later stages of core loading, when there are assemblies adjacent to each other in three or four directions. One power plant even experienced a record of loading a single deformed fuel assembly taking six hours.

[0004] In order to solve the problem that the deformed fuel assembly cannot be seated, most countries in the world currently use loading auxiliary devices. However, this loading auxiliary tool must occupy the space of 3 core fuel units. In the early stage of loading, when the core space is sufficient, the core fuel loading can be successfully completed using this tool. However, in the later stage of loading, the loading auxiliary tool must occupy the empty space of 3 units around the assembly to be placed when it is used. Therefore, when the remaining space on the core bottom plate is narrow, the auxiliary tool cannot be used. Even if the assembly to be installed has three surfaces to form constraints, during the lowering process of the assembly, due to its own deformation or the deformation of the surrounding installed components, it may still deviate to the unconstrained direction after the three sides of the core are tightly attached, making it impossible to successfully complete the loading of the assembly. Typical cases are Figure 3 shown.

[0005] Currently, adjusting the loading sequence can address the difficulty of completing assembly loading in the later stages of core loading. This method aims to adjust the loading sequence of core fuel assemblies so that as many of the three-unit loading aids as possible can provide guidance for fuel assembly loading. However, typical pressurized water reactor loading sequences typically have 121, 157, or 177 steps. Existing core loading sequence adjustments manually calculate potential loading difficulty locations one by one, resulting in numerous inconveniences and omissions. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for determining the feasibility of a core loading sequence for a pressurized water reactor nuclear power unit. This method can solve the problem of quickly determining that deformed fuel assemblies may cause loading difficulties in individual positions, and can automatically determine the positions of fuel assemblies that are difficult to load. This not only solves the problem of manually adjusting and verifying the loading sequence one by one, but also avoids some possible loading difficulties, greatly reducing work difficulty, improving work efficiency, and ensuring the safety of nuclear fuel and the progress of nuclear power plant overhauls.

[0007] The technical solution of the present invention is as follows: A method for determining the feasibility of a core loading sequence for a pressurized water reactor nuclear power plant comprises the following steps:

[0008] Step 1: First, sort all core physical locations from small to large according to the loading order;

[0009] Step 2: Establish a nine-square grid coordinate system, use the position of each fuel assembly to be determined as the center Mid of the nine-square grid coordinate system, and mark its position;

[0010] Step 3: Mark the corresponding core physical positions in the order of arrangement. After each marking, call the related function RelatedFunction to update the associated nine-square grid coordinate system and use different assignments to distinguish new fuel assemblies from old fuel assemblies.

[0011] Step 4: After calling the related function RelatedFunction at each step, the charging feasibility function EstimateFunction is called immediately;

[0012] Step 5: Continue to determine the position of step 84 E2 using the method in steps 3 and 4. If there is a loading difficulty, mark it and proceed to the next step. If there is no loading difficulty, proceed directly to the next step.

[0013] The method of sorting from small to large in step 1 is a bubble sort method.

[0014] The center Mid described in step 2 is recorded as Top, Bottom, Left, and Right respectively, and the upper left, lower left, upper right, and lower right positions are LeftTop, LeftBottom, RightTop, and RightBottom respectively.

[0015] In step 2, all core physical coordinate positions can be correlated with each other through the nine-square grid coordinate system. This correlation process is taken as a whole and defined as a correlation function called RelatedFunction.

[0016] The relevant content of the correlation function is: (B2.Top=A2.Mid)&(B2.Bottom=C2.Mid)&(B2.Left=B1.Mid)&(B2.Right=B3.Mid)&(B2.Ltop=A1.Mid)&(B2.Lbot=C1.Mid)&(B2.Rtop=A3.Mid)&(B2.Rbot=C3.Mid).

[0017] In step 4, the position of the component to be installed is Mid, and the blank space is the position without components. According to the number of positions without components in the nine-square grid coordinate system, they are divided into two major categories, and each subcategory is the position after the layout form is rotated 90 degrees.

[0018] In step 4, if the deformation direction of the loaded component is in the direction of the component to be installed and there is no space for placing loading auxiliary tools, the component to be installed cannot be put into place. The first judgment function or the second judgment function is called in sequence to determine the core position where loading is difficult.

[0019] In the step 4,

[0020] The first judgment function of EstimateFunction is: IF(D2.Left=1 or 2)&(D2.Right=1 or 2)&(D2.Lbot=1 or 2)&(D2.Rbot=1 or 2)&(D2.Top=2 OR D2.Mid=2)ThenD2.Estimate=False;

[0021] The second judgment function of EstimateFunction is: IF(D2.Ltop=1 or 2)&(D2.Lbot=1 or 2)&(D2.Rbot=1 or 2)&(D2.Top=2 OR D2.Right=2 OR D2.Mid=2)Then D2.Estimate=False.

[0022] In step 5, the method in steps 3 and 4 is followed and the process is repeated until the last step of the loading sequence.

[0023] The beneficial effect of the present invention is that the method can assist in quickly judging the feasibility of the loading sequence, thereby avoiding omissions, and effectively reducing the time of the main line loading task of the nuclear power plant overhaul while ensuring the safety of nuclear fuel, thereby improving work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the fuel assembly deformation type;

[0025] Figure 2 This is a schematic diagram of a situation where a deformed component cannot be put into place;

[0026] Figure 3 This is a schematic diagram of a typical situation where the device cannot be positioned;

[0027] Figure 4 It is a schematic diagram of the nine-square grid coordinate system;

[0028] Figure 5 This is a schematic diagram of the core physical coordinates;

[0029] Figure 6 Schematic diagram of the related function RelatedFunction;

[0030] Figure 7 This is a schematic diagram of the judgment function EstimateFunction;

[0031] Figure 8 This is a logical diagram of the method provided by the present invention for judging the feasibility of the core loading sequence of a pressurized water reactor nuclear power unit. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] A method for determining the feasibility of a core loading sequence for a pressurized water reactor nuclear power unit is disclosed. The method mainly calculates the feasibility of the loading sequence by comprehensively judging whether loading auxiliary tools can be placed and the age of the component to be loaded and the surrounding components.

[0034] like Figure 8 As shown, the method for determining the feasibility of the core loading sequence of a pressurized water reactor nuclear power plant unit includes the following steps:

[0035] Step 1: First, sort all the core physical positions from small to large according to the loading order. Since the pressurized water reactor nuclear fuel is loaded in a serpentine manner, there is a difference between the loading order and the arrangement of the core physical positions. For example, the position with the loading order of 3 is numbered as B10. Figure 5 As shown, A to N are the vertical coordinates of the core physical coordinate system. Therefore, it is necessary to sort all the core physical positions from small to large according to the loading order. There are many sorting methods, such as bubble sort;

[0036] Step 2: Establish a nine-square grid coordinate system. Take the position of each fuel assembly to be determined as the center Mid of the nine-square grid coordinate system (for example: A1.Mid). Its top, bottom, left, and right directions are recorded as Top / Bottom / Left / Right respectively. The top left, bottom left, top right, and bottom right directions are recorded as LeftTop / LeftBottom / RightTop / RightBottom (abbreviated as Ltop, Lbot, Rtop, Rbot) respectively. Figure 4 Through the nine-square grid coordinate system, all core physical coordinate positions can be related to each other, so that the ② position C3.Ltop (upper left) is the same as the ① position B2.Mid (center), that is, C3.Ltop = B2.Mid. For example, Figure 6 As shown. Use the same method to associate all core physical positions through the nine-square grid coordinate system, and define this association process as a whole as a mutual correlation function called RelatedFunction. The relevant content of the correlation function is: (B2.Top=A2.Mid)&(B2.Bottom=C2.Mid)&(B2.Left=B1.Mid)&(B2.Right=B3.Mid)&(B2.Ltop=A1.Mid)&(B2.Lbot=C1.Mid)&(B2.Rtop=A3.Mid)&(B2.Rbot=C3.Mid), and the same applies to other core physical coordinate positions;

[0037] Step 3: Mark the corresponding physical positions of the core in order of arrangement. After each marking, call the related function RelatedFunction to update the associated nine-square grid coordinate system, and use different assignments to distinguish new fuel assemblies from old fuel assemblies.

[0038] Combine Figure 5 Analyzing the core's physical coordinate D2, the 83rd step to be installed, the correlation function shows that, assuming D2 in step 83 is Mid, steps E3 in step 82 and D3 in step 67 represent the newly installed fuel assembly, with D2.RBot = E3.Mid = 1 and D2.Right = D3.Mid = 1, respectively. Step C3 in step 66 represents the installed old fuel assembly, with Rtop = 2. Furthermore, the assembly to be installed, above / left, left, and bottom left, is located on the core panel and exhibits no deformation. Therefore, it can be abstractly defined as a new fuel assembly, with D2.Top = 1, D2.Ltop = 1, D2.Left = 1, and D2.Lbot = 1.

[0039] Step 4: After calling the related function RelatedFunction at each step, the charging feasibility function EstimateFunction is called immediately. Figure 7As shown, the EstimateFunction judgment function is divided into two major categories: the first judgment function and the second judgment function. Each major category has four subcategories. The position of the component to be installed is Mid, and the blank space is the position without components. According to the number of positions without components in the nine-square grid coordinate system, it is divided into two major categories. Each subcategory is the position after the layout form is rotated 90 degrees. Figure 7 As shown, if the deformation direction of the loaded component is in the direction of the component to be loaded and there is no space for loading auxiliary tools, the component to be loaded may not be able to be loaded. By calling the first and second judgment functions in sequence, it is possible to quickly determine the core location where loading is difficult.

[0040] The first judgment function of EstimateFunction is: IF(D2.Left=1 or 2)&(D2.Right=1 or 2)&(D2.Lbot=1 or 2)&(D2.Rbot=1 or 2)&(D2.Top=2 OR D2.Mid=2)ThenD2.Estimate=False.

[0041] The second judgment function of EstimateFunction is: IF(D2.Ltop=1 or 2)&(D2.Lbot=1 or 2)&(D2.Rbot=1 or 2)&(D2.Top=2 OR D2.Right=2 OR D2.Mid=2)Then D2.Estimate=False.

[0042] like Figure 5 As shown, B2, D2 and other codes are the core physical coordinate numbers, A~N are the vertical coordinates of the core physical coordinates, and 1~13 are the horizontal coordinates of the core physical coordinates.

[0043] like Figure 7 As shown, after calling the related function RelatedFunction at position D2 in step 83, we get (D2.Left=1)&(D2.Right=2)&(D2.Lbot=1)&(D2.Rbot=1)&(D2.Mid=2), which is consistent with the first case in the first judgment function. That is, if the component at step D2 in step 83 is deformed, it cannot be successfully installed into the core. Therefore, step D2 in step 83 is recorded as the step that may not be installed into the core, and D2.Estimate = False;

[0044] Step 5: Continue to determine the position E2 in step 84 using the same method. If there is a loading difficulty, mark it and proceed to the next step. If there is no loading difficulty, proceed directly to the next step. This cycle continues until the last step of the loading sequence.

Claims

1. A method for determining the feasibility of a core loading sequence for a pressurized water reactor nuclear power plant, characterized in that: The steps include: Step 1: First, sort all core physical locations from small to large according to the loading order; Step 2: Establish a nine-square grid coordinate system, use the position of each fuel assembly to be determined as the center Mid of the nine-square grid coordinate system, and mark its position; Its top, bottom, left and right directions are recorded as Top / Bottom / Left / Right respectively, and the top left, bottom left, top right and bottom right directions are recorded as LeftTop / LeftBottom / RightTop / RightBottom respectively, abbreviated as Ltop, Lbot, Rtop, Rbot. Step 3: Mark the corresponding core physical positions in the order of arrangement. After each marking, call the related function RelatedFunction to update the associated nine-square grid coordinate system and use different assignments to distinguish new fuel assemblies from old fuel assemblies. Step 4: After calling the related function RelatedFunction at each step, the charging feasibility function EstimateFunction is called immediately. The related function RelatedFunction is: (B2.Top=A2.Mid)&(B2.Bottom=C2.Mid)&(B2.Left=B1.Mid)&(B2.Right=B3.Mid)&(B2.Ltop=A1.Mid)&(B2.Lbot=C1.Mid)&(B2.Rtop=A3.Mid)&(B2.Rbot=C3.Mid), The B2 and D2 codes are the core physical coordinate numbers, A to N are the vertical coordinates of the core physical coordinates, and 1 to 13 are the horizontal coordinates of the core physical coordinates; The position of the component to be installed is Mid, and the blank space is the position without components. According to the number of positions without components in the nine-square grid coordinate system, they are divided into two major categories. Each subcategory is the position after the layout form is rotated 90 degrees; If the deformation direction of the loaded component is in the direction of the component to be loaded and there is no space for the loading auxiliary tool, the component to be loaded cannot be put into place, and the first judgment function or the second judgment function is called in sequence to determine the core position where loading is difficult; The first judgment function of EstimateFunction is: IF (D2.Left=1 or 2) & (D2.Right=1 or 2) &(D2.Lbot=1 or 2) & (D2.Rbot=1 or 2) & (D2.Top=2 OR D2.Mid=2) Then D2.Estimate=False; The second judgment function of EstimateFunction is: IF (D2.Ltop=1 or 2) & (D2.Lbot=1 or 2) &(D2.Rbot=1 or 2)&(D2.Top=2 OR D2.Right=2 OR D2.Mid=2)Then D2.Estimate=False; Step 5: Continue to determine the position of step 84 E2 using the method in steps 3 and 4. If there is a loading difficulty, mark it and proceed to the next step. If there is no loading difficulty, proceed directly to the next step.

2. The method for determining the feasibility of a core loading sequence for a pressurized water reactor nuclear power plant according to claim 1, wherein: The method of sorting from small to large in step 1 is a bubble sort method.

3. The method for determining the feasibility of a core loading sequence for a pressurized water reactor nuclear power plant according to claim 1, wherein: In step 2, all core physical coordinate positions can be correlated with each other through the nine-square grid coordinate system. This correlation process is taken as a whole and defined as a correlation function called RelatedFunction.

4. The method for determining the feasibility of a core loading sequence for a pressurized water reactor nuclear power plant according to claim 1, wherein: In step 5, the method in steps 3 and 4 is followed and the process is repeated until the last step of the loading sequence.

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