Spent fuel storage grillwork spacing monitoring method

Abstract

The invention relates to a spent fuel storage grillwork spacing monitoring method, and belongs to the technical field of measurement of spacing of separated objects. According to the method, a displacement sensor is installed on a grillwork, and a spent fuel pool is used as a reference of a coordinate system. The grillwork at one corner of the pool is selected as a first grillwork, and two probes are selected on the two adjacent side faces of the pool wall respectively to calculate the deflection angle of the first grillwork. The offset of the first grillwork on the x-axis and the y-axis is obtained by calculating the theoretical change value of the extension length of the probe, so that the deflection coordinates of the four base angles of the first grillwork are obtained. Then, the deflection coordinates of the four base angles of the grillwork located in the same row as the first grillwork are solved, the process is repeated in sequence according to the row, finally, the deflection coordinates of the four base angles of all the grillwork are obtained, and a linear equation of the bottom edges of the grillwork is generated; and finally, calculating the distance from the base angle to the bottom edge and the pool wall, and taking the minimum value as the space between the grillwork and the pool wall. According to the method, the monitoring precision of the distance is improved in a physical quantity expansion and contraction mode.

Description

Technical Field

[0001] The invention relates to a method for monitoring the spacing of racks storing spent fuel, and belongs to the technical field of measuring the spacing of objects separated from each other (G01B7 / 14). Background Art

[0002] Spent fuel storage grids are key equipment in nuclear power plants. They are usually densely arranged in a square shape and placed in a square spent fuel pool. They are mainly used to safely store spent fuel assemblies. Normally, the bottom legs of the spent fuel storage grids are not welded to the bottom of the pool. Therefore, under the action of external forces, such as after multiple loading and unloading of spent fuel assemblies, the spent fuel storage grids may slip, causing changes in position. If the spent fuel storage grids slip and collide, it may not only cause damage to the grids, but also affect the integrity of the spent fuel assemblies, thereby increasing the risk of radioactive leakage. Therefore, in order to ensure the safe storage of spent fuel assemblies, the distance between the grids and the distance between the grids and the pool wall must be monitored in real time.

[0003] Currently, the spacing of spent fuel storage racks is mostly measured by non-contact measurement methods such as underwater cameras. However, due to the influence of factors such as light and water temperature, these methods have certain shortcomings in positioning accuracy and cannot accurately determine the precise distance between racks and between racks and the pool wall.

[0004] Therefore, there is an urgent need for a grid spacing monitoring method that can monitor the storage of spent fuel with high precision to ensure the safe storage of spent fuel assemblies, which is of great significance to the safe operation and accident prevention of nuclear power plants. Summary of the invention

[0005] The technical problem to be solved by the present invention is: how to achieve high-precision monitoring of the grid spacing of the stored spent fuel.

[0006] The technical solution proposed by the present invention to solve the above technical problems is: a method for monitoring the spacing of a grid for storing spent fuel, wherein the cross section of the grid is square and is placed in a square water pool, comprising the following steps:

[0007] Step 1: placing at least four displacement sensors on each grid, so that the probe of each displacement sensor is perpendicular to the side of the grid adjacent to it;

[0008] At least two probes extend from one side of one of the two adjacent grids and abut against an adjacent side of the other grid;

[0009] At least two probes extend from a side of the grid adjacent to the pool wall and abut against the adjacent pool wall;

[0010] Step 2: Establish a plane coordinate system with the vertex of the upper left corner of the pool as the origin and the two mutually perpendicular pool edges forming the upper left corner of the pool as the x-axis and y-axis respectively;

[0011] The grid located in the upper left corner of the pool is used as the first grid;

[0012] The probes extending from two mutually perpendicular side surfaces of the first frame are respectively pressed against two mutually perpendicular pool walls at the upper left corner of the pool;

[0013] Of the two mutually perpendicular sides of the first grid, the side parallel to the x-axis is recorded as the first transverse side, and the side parallel to the y-axis is recorded as the first longitudinal side;

[0014] Select any two probes extending from the first longitudinal side surface, and use the probes closer to and farther from the x-axis as the first probe and the second probe respectively; select any two probes extending from the first transverse side surface, and use the probes closer to and farther from the y-axis as the third probe and the fourth probe respectively;

[0015] Step 2.1: Read the actual change value x of the extension length of the first probe, the second probe, the third probe and the fourth probe in real time 1 、x 2 ,y 1 and 2 ;

[0016] The deflection angle α of the first grid is calculated according to the following formula (1):

[0017] (1);

[0018] In formula (1), is the vertical distance between the first probe and the second probe;

[0019] Step 2.2: Calculate the theoretical change in the extension length of the second probe when the first frame rotates around the center point of its bottom surface by the deflection angle α according to the following formula (2): and the theoretical change value of the extension length of the third probe

[0020] (2);

[0021] In formula (2), is the distance between the bottom corner of the first longitudinal side surface that is farther from the second probe and the second probe; is the distance between the bottom corner on the first lateral side which is farther from the third probe and the third probe;

[0022] Step 2.3: Calculate the first x-axis offset of the center point of the bottom surface of the first grid according to formula (3) and the first y-axis offset

[0023] (3);

[0024] In formula (3), is the x-axis offset of the grid against which the first and second probes abut. If the first and second probes abut not against the grid but against the wall of the pool, Take 0; is the y-axis offset of the grid against which the third and fourth probes abut. If the third and fourth probes abut not against the grid but against the wall of the pool, Take 0;

[0025] Step 2.4: Calculate the offset coordinates of the four bottom corners of the first grid according to the following formula (4): , )

[0026] (4);

[0027] In formula (4), ( , ) are the initial coordinates of the four bottom corners of the first grid; ( , ) is the initial coordinate of the center point of the bottom surface of the first grid;

[0028] Step 3: using a grid adjacent to the first grid along the x-axis direction as a second grid;

[0029] The probe extending from one of the two mutually perpendicular side surfaces of the second frame abuts against the adjacent pool wall, and the probe extending from the other side abuts against the adjacent side surface of the first frame;

[0030] One of the two mutually perpendicular side surfaces of the second grid is recorded as a second transverse side surface, and the other side surface is recorded as a second longitudinal side surface;

[0031] Select any two probes extending from the second longitudinal side surface, and use the probes closer to and farther from the x-axis as the fifth probe and the sixth probe respectively; select any two probes extending from the second transverse side surface, and use the probes closer to and farther from the y-axis as the seventh probe and the eighth probe respectively;

[0032] Read the actual change value x of the extension length of the fifth probe, the sixth probe, the seventh probe and the eighth probe in real time 4 、x 5 ,y 4 and 5 ;

[0033] The deflection angle of the second grid is calculated according to the following formula (5):

[0034] (5);

[0035] In formula (5), is the vertical distance between the fifth probe and the sixth probe;

[0036] The first transverse side surface, the first longitudinal side surface, the second probe and the third probe in formula (2) are replaced by the second transverse side surface, the second longitudinal side surface, the sixth probe and the seventh probe respectively, and the deflection angle of the second grid rotating around the center point of its bottom surface is calculated according to the principle of formula (2): The theoretical change value of the extension length of the sixth probe and the theoretical change value of the extension length of the seventh probe;

[0037] The first probe, the second probe, the third probe and the fourth probe in formula (3) are replaced by the fifth probe, the sixth probe, the seventh probe and the eighth probe respectively, and the second x-axis offset and the second y-axis offset of the center point of the bottom surface of the second grid are calculated according to the principle of formula (3);

[0038] Replace the first grid in formula (4) with the second grid, and calculate the offset coordinates of the four bottom corners of the second grid according to the principle of formula (4);

[0039] Then, the grid adjacent to the second grid along the x-axis direction is used as the third grid, and so on, until the offset coordinates of the four bottom corners of all grids in the same row as the first grid are calculated;

[0040] Step 4: taking the grid adjacent to the first grid along the y-axis direction as a new first grid;

[0041] The probe extending from one of the two mutually perpendicular side surfaces of the new first frame abuts against the adjacent side surface of the first frame, and the probe extending from the other side abuts against the adjacent pool wall;

[0042] One of the two mutually perpendicular side surfaces of the new first grid is recorded as a new transverse side surface, and the other side surface is recorded as a new longitudinal side surface;

[0043] Select any two probes extending from the new first longitudinal side surface, and use the probes closer to and farther from the x-axis as the new first probe and the new second probe respectively; select any two probes extending from the new first transverse side surface, and use the probes closer to and farther from the y-axis as the new third probe and the new fourth probe respectively;

[0044] Repeat steps 2.1-3 until the offset coordinates of the four bottom corners of all grids in the same row as the new first grid are calculated;

[0045] This process is deduced in this way until the offset coordinates of the four bottom corners of all the grids in the pool are calculated;

[0046] Step 5: Generate the straight line equation of each bottom side of each grid according to the offset coordinates of the four bottom corners of each grid obtained in step 4;

[0047] Generate a straight line equation of each pool edge of the pool according to the coordinates of the four corners of the pool in the plane coordinate system;

[0048] For the four adjacent bottom corners and two adjacent bottom sides of two adjacent grids, the distance values ​​from the four adjacent bottom corners to the adjacent bottom sides are obtained in real time according to the point-to-straight line distance formula, and the minimum distance value is taken as the spacing between the two adjacent grids;

[0049] For the two bottom corners of one side of the grid adjacent to the pool wall, the distance values ​​between the two bottom corners and the pool wall are obtained in real time according to the point-to-straight-line distance formula, and the minimum distance value is taken as the spacing between the side of the grid and the adjacent pool wall.

[0050] Furthermore, the step 2.1 can also calculate the deflection angle α of the first grid according to the following formula (6):

[0051] (6);

[0052] In formula (6), is the vertical distance between the third probe and the fourth probe.

[0053] Furthermore, step 5 is generated in real time by using mathematical software MATLAB in the host computer.

[0054] The beneficial effect of the present invention is that since the displacement sensor is installed on the grid, the distance change between the grids can be reflected in real time through the extension and contraction amount of the displacement sensor probe, which can not only show the deflection direction of the grid, but also avoid the interference of external factors such as light and water temperature, and effectively improve the accuracy of the grid spacing measurement. In addition, when calculating the grid spacing, the determined grid is used as the calculation basis of the adjacent grid, and the calculation result of the adjacent grid is corrected, thereby further improving the accuracy of the grid spacing monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The present invention will be further described below in conjunction with the accompanying drawings.

[0056] Figure 1 Schematic diagram of a grid used in a method for monitoring grid spacing for storing spent fuel according to an embodiment.

[0057] Figure 2 It is a top view of a grid placed in a water pool in the method for monitoring the grid spacing for storing spent fuel in an embodiment.

[0058] Figure 3 yes Figure 2 A magnified image of

[0059] Figure 4 It is a schematic diagram of the deviation of the first grid in the method for monitoring the grid spacing for storing spent fuel in an embodiment.

[0060] In the figure: 1, first grid; 2, second grid; 3, new first grid. DETAILED DESCRIPTION

[0061] Example

[0062] The method for monitoring the grid spacing of spent fuel storage in this embodiment is as follows: Figure 1 and Figure 2 As shown, the cross section of the grid is a square of 1500mm×1500mm, and is placed in a rectangular pool with a spacing of 50mm between two grids, including the following steps:

[0063] Step 1: placing at least four displacement sensors on each grid, so that the probe of each displacement sensor is perpendicular to the side of the grid adjacent to it;

[0064] like Figure 2 As shown, in this embodiment, four displacement sensors are arranged on each grid;

[0065] At least two probes extend from one side of one of the two adjacent grids and abut against an adjacent side of the other grid;

[0066] At least two probes extend from one side of the grid adjacent to the pool wall and abut against the adjacent pool wall;

[0067] Step 2: If Figure 2 As shown, a plane coordinate system is established with the vertex of the upper left corner of the pool as the origin, and the two mutually perpendicular pool edges forming the upper left corner of the pool as the x-axis and y-axis respectively;

[0068] The grid located in the upper left corner of the pool is referred to as the first grid 1;

[0069] like Figure 3 As shown, the probes extending from the two mutually perpendicular side surfaces of the first frame 1 are respectively against the two mutually perpendicular pool walls at the upper left corner of the pool;

[0070] Of the two mutually perpendicular side surfaces of the first frame 1, the side surface parallel to the x-axis is recorded as the first transverse side surface, and the side surface parallel to the y-axis is recorded as the first longitudinal side surface;

[0071] Select any two probes extending from the first longitudinal side surface, and use the probes closer to and farther from the x-axis as the first probe and the second probe respectively; select any two probes extending from the first transverse side surface, and use the probes closer to and farther from the y-axis as the third probe and the fourth probe respectively;

[0072] In this embodiment, when the grid is not offset, the initial extension length of all probes is 10 mm;

[0073] After multiple loading and unloading of spent fuel assemblies, Figure 4 As shown, the first grid 1 is offset;

[0074] Step 2.1: Read the actual change value x of the extension length of the first probe, the second probe, the third probe and the fourth probe in real time 1 =20mm, x 2 =50mm,y 1 =50mm,y 2 =20mm;

[0075] The deflection angle α of the first grid 1 is calculated by the following formula (1):

[0076] (1);

[0077] In formula (1), the vertical distance between the first probe and the second probe is =1000mm;

[0078] In this embodiment, the deflection angle α calculated according to formula (1) is 1.72°;

[0079] In this step, the present embodiment can also use the third probe and the fourth probe on the first lateral side to calculate the deflection angle α of the first grid 1.

[0080] According to the formula Find the vertical distance between the third probe and the fourth probe =1000mm;

[0081] Step 2.2: Calculate the theoretical change in the extension length of the second probe when the first frame 1 rotates around the center point of its bottom surface by an angle of α, that is, 1.72°, according to formula (2): The theoretical change of the extension length of the third probe

[0082] (2);

[0083] In formula (2), the distance between the bottom corner on the first longitudinal side that is farther from the second probe and the second probe is =1250mm; the distance between the bottom corner farther from the third probe on the first lateral side and the third probe =1250mm;

[0084] In this embodiment, the formula (2) is used to calculate =37.5mm, = 37.5mm;

[0085] Step 2.3: Calculate the first x-axis offset of the center point of the bottom surface of the first grid 1 according to formula (3). and the first y-axis offset

[0086] (3);

[0087] In formula (3), is the x-axis offset of the grid against which the first and second probes abut. If the first and second probes abut not against the grid but against the pool wall, Take 0; is the y-axis offset of the grid against which the third and fourth probes abut. If the third and fourth probes abut not against the grid but against the pool wall, Take 0;

[0088] In this embodiment, since the first probe, the second probe, the third probe and the fourth probe are all against the wall of the pool, and the wall of the pool will not deviate, there is no need to adjust the first x-axis offset. and the first y-axis offset Make corrections, so and Take 0;

[0089] In this embodiment, the formula (3) is used to calculate =12.5mm, =12.5mm;

[0090] Step 2.4: Calculate the offset coordinates of the four bottom corners of the first grid 1 according to formula (4) , )

[0091] (4);

[0092] In formula (4), ( , ) are the initial coordinates of the four bottom corners of the first grid 1; ( , ) is the initial coordinate of the center point of the bottom surface of the first grid 1;

[0093] In this embodiment, the initial coordinates of the four bottom corners of the first frame 1 are (50, 50), (50, 1550), (1550, 1550) and (1550, 50), respectively; the initial coordinates of the center point of the bottom surface of the first frame 1 are (800, 800); according to formula (4), the offset coordinates of the four bottom corners of the first frame 1 are (40.32, 85.36), (85.36, 1584.68), (1584.68, 1539.65) and (1539.65, 40.32), respectively.

[0094] Step 3: The grid adjacent to the first grid 1 along the x-axis direction is used as the second grid 2;

[0095] like Figure 4 As shown, the probe extending from one of the two mutually perpendicular side surfaces of the second grid abuts against the adjacent pool wall, and the probe extending from the other side abuts against the adjacent side surface of the first grid;

[0096] One of the two mutually perpendicular side surfaces of the second frame is recorded as a second transverse side surface, and the other side surface is recorded as a second longitudinal side surface;

[0097] Select any two probes extending from the second longitudinal side surface, and use the probes closer to and farther from the x-axis as the fifth probe and the sixth probe respectively; select any two probes extending from the second transverse side surface, and use the probes closer to and farther from the y-axis as the seventh probe and the eighth probe respectively;

[0098] Read the actual change value x of the extension length of the fifth probe, the sixth probe, the seventh probe and the eighth probe in real time 4 、x 5 ,y 4 and 5 ;

[0099] Since the first grid 1 is offset, the deflection angle of the second grid 2 is calculated. Correction is required; the deflection angle of the second grid 2 is calculated according to the following formula (5):

[0100] (5);

[0101] In formula (5), the vertical distance between the fifth probe and the sixth probe is =1000mm;

[0102] In this step, the present embodiment can also use the seventh probe and the eighth probe on the second lateral side to calculate the deflection angle of the second grid 2. Since the seventh and eighth probes are against the pool wall, no correction is required, that is, according to the formula Ask for, is the vertical distance between the seventh probe and the eighth probe;

[0103] The first transverse side surface, the first longitudinal side surface, the second probe and the third probe in formula (2) are replaced by the second transverse side surface, the second longitudinal side surface, the sixth probe and the seventh probe, respectively. The rotation deflection angle of the second grid 2 around the center point of its bottom surface is calculated according to the principle of formula (2): The theoretical change value of the extension length of the sixth probe and the theoretical change value of the extension length of the seventh probe;

[0104] The first probe, the second probe, the third probe and the fourth probe in formula (3) are replaced by the fifth probe, the sixth probe, the seventh probe and the eighth probe respectively, and the second x-axis offset and the second y-axis offset of the center point of the bottom surface of the second grid 2 are calculated according to the principle of formula (3);

[0105] Since the first grid 1 is offset, the second x-axis offset of the center point of the bottom surface of the second grid 2 needs to be corrected when calculating it. The x-axis offset of the grid on which the fifth and sixth probes are pressed, i.e., the first grid, needs to be added. The correction of the second y-axis offset should be to add the y-axis offset of the grid on which the seventh and eighth probes are pressed. However, since the seventh and eighth probes are pressed against the wall of the pool, is also taken as 0; that is, when calculating the y-axis offset of the grid adjacent to the second grid 2 along the y-axis direction, the y-axis offset of that adjacent grid should be corrected by adding the second y-axis offset;

[0106] Replace the first grid in equation (4) with the second grid, and calculate the offset coordinates of the four bottom corners of the second grid according to the principle of equation (4);

[0107] Then, the grid adjacent to the second grid 2 along the x-axis direction is used as the third grid, and so on, until the offset coordinates of the four bottom corners of all grids in the same row as the first grid 1 are calculated;

[0108] Step 4: taking the grid adjacent to the first grid 1 along the y-axis direction as the new first grid 3;

[0109] like Figure 4 As shown, the probe extending from one of the two mutually perpendicular side surfaces of the new first grid abuts against the adjacent side surface of the first grid, and the probe extending from the other side abuts against the adjacent pool wall;

[0110] One of the two mutually perpendicular sides of the new first grid is recorded as a new transverse side, and the other side is recorded as a new longitudinal side;

[0111] Select any two probes extending from the new first longitudinal side surface, and use the probes closer to and farther from the x-axis as the new first probe and the new second probe respectively; select any two probes extending from the new first transverse side surface, and use the probes closer to and farther from the y-axis as the new third probe and the new fourth probe respectively;

[0112] Repeat steps 2.1-3 until the offset coordinates of the four bottom corners of all grids in the same row as the new first grid 3 are calculated;

[0113] And so on, until the offset coordinates of the four bottom corners of all the grids in the pool are calculated.

[0114] Step 5: Generate the straight line equation of each bottom side of each grid according to the offset coordinates of the four bottom corners of each grid obtained in step 4;

[0115] Determining a straight line equation from two points is a conventional prior art. In this embodiment, the mathematical software MATLAB is used in the host computer to generate the equation in real time.

[0116] And according to the coordinates of the four corners of the pool in the plane coordinate system, generate the straight line equation of each edge of the pool;

[0117] like Figure 4 As shown, for the four adjacent bottom corners and two adjacent bottom sides of two adjacent grids, the distance values ​​from the four adjacent bottom corners to the adjacent bottom sides are obtained in real time according to the point-to-straight line distance formula, that is, the distance values ​​from the two bottom corners on one grid to the adjacent bottom sides of another grid, a total of four distance values, and the minimum distance value is taken as the spacing between the two adjacent grids;

[0118] In this embodiment, two adjacent grids are the first grid 1 and the second grid 2, and the obtained distance between the first grid 1 and the second grid 2 is 15.32 mm.

[0119] For the two bottom corners of one side of the grid adjacent to the pool wall, the distance values ​​between the two bottom corners and the pool wall are obtained in real time according to the point-to-straight-line distance formula, and the minimum distance value is taken as the distance between one side of the grid and the adjacent pool wall;

[0120] In this embodiment, based on the two bottom angles of the longitudinal side surface of the first grid 1 adjacent to the pool wall, it is obtained that the distance between the longitudinal side surface of the first grid 1 and the pool wall is 40.32 mm.

[0121] The above description is only a preferred embodiment of the present invention, but the present invention is not limited thereto. All equivalent replacements or equivalent changes of the concepts and technical solutions according to the present invention should be included in the protection scope of the present invention.

Claims

1. A method for monitoring the spacing of a grid for storing spent fuel, wherein the grid has a square cross section and is placed in a rectangular pool, characterized in that The steps include: Step 1: placing at least four displacement sensors on each grid, so that the probe of each displacement sensor is perpendicular to the side of the grid adjacent to it; At least two probes extend from one side of one of the two adjacent grids and abut against an adjacent side of the other grid; At least two probes extend from a side of the grid adjacent to the pool wall and abut against the adjacent pool wall; Step 2: Establish a plane coordinate system with the vertex of the upper left corner of the pool as the origin and the two mutually perpendicular pool edges forming the upper left corner of the pool as the x-axis and y-axis respectively; The grid located in the upper left corner of the pool is used as the first grid; The probes extending from the two mutually perpendicular side surfaces of the first frame are respectively pressed against the two mutually perpendicular pool walls at the upper left corner of the pool; Of the two mutually perpendicular sides of the first grid, the side parallel to the x-axis is recorded as the first transverse side, and the side parallel to the y-axis is recorded as the first longitudinal side; Select any two probes extending from the first longitudinal side surface, and use the probes closer to and farther from the x-axis as the first probe and the second probe respectively; select any two probes extending from the first transverse side surface, and use the probes closer to and farther from the y-axis as the third probe and the fourth probe respectively; Step 2.1: Reading in real time the actual change values ​​x1, x2, y1 and y2 of the extension lengths of the first probe, the second probe, the third probe and the fourth probe; The deflection angle α of the first grid is calculated according to the following formula (1): （1）； In formula (1), is the vertical distance between the first probe and the second probe; Step 2.2: Calculate the theoretical change in the extension length of the second probe when the first frame rotates around the center point of its bottom surface by the deflection angle α according to the following formula (2): and the theoretical change value of the extension length of the third probe （2）； In formula (2), is the distance between the bottom corner of the first longitudinal side surface that is farther from the second probe and the second probe; is the distance between the bottom corner on the first lateral side which is farther from the third probe and the third probe; Step 2.3: Calculate the first x-axis offset of the center point of the bottom surface of the first grid according to the following formula (3): and the first y-axis offset （3）； In formula (3), is the x-axis offset of the grid against which the first and second probes abut. If the first and second probes abut not against the grid but against the wall of the pool, Take 0; is the y-axis offset of the grid against which the third and fourth probes abut. If the third and fourth probes abut not against the grid but against the wall of the pool, Take 0; Step 2.4: Calculate the offset coordinates of the four bottom corners of the first grid according to the following formula (4): , ) （4）； In formula (4), ( , ) are the initial coordinates of the four bottom corners of the first grid; ( , ) is the initial coordinate of the center point of the bottom surface of the first grid; Step 3: using a grid adjacent to the first grid along the x-axis direction as a second grid; The probe extending from one of the two mutually perpendicular side surfaces of the second frame abuts against the adjacent pool wall, and the probe extending from the other side abuts against the adjacent side surface of the first frame; One of the two mutually perpendicular side surfaces of the second grid is recorded as a second transverse side surface, and the other side surface is recorded as a second longitudinal side surface; Select any two probes extending from the second longitudinal side surface, and use the probes closer to and farther from the x-axis as the fifth probe and the sixth probe respectively; Select any two probes extending from the second transverse side surface, and use the probes closer to and farther from the y-axis as the seventh probe and the eighth probe respectively; Reading in real time the actual change values ​​x4, x5, y4 and y5 of the extension lengths of the fifth probe, the sixth probe, the seventh probe and the eighth probe; The deflection angle of the second grid is calculated according to the following formula (5): （5）； In formula (5), is the vertical distance between the fifth probe and the sixth probe; The first transverse side surface, the first longitudinal side surface, the second probe and the third probe in formula (2) are replaced by the second transverse side surface, the second longitudinal side surface, the sixth probe and the seventh probe respectively, and the deflection angle of the second grid rotating around the center point of its bottom surface is calculated according to the principle of formula (2): The theoretical change value of the extension length of the sixth probe and the theoretical change value of the extension length of the seventh probe; The first probe, the second probe, the third probe and the fourth probe in formula (3) are replaced by the fifth probe, the sixth probe, the seventh probe and the eighth probe respectively, and the second x-axis offset and the second y-axis offset of the center point of the bottom surface of the second grid are calculated according to the principle of formula (3); Replace the first grid in formula (4) with the second grid, and calculate the offset coordinates of the four bottom corners of the second grid according to the principle of formula (4); Then, the grid adjacent to the second grid along the x-axis direction is used as the third grid, and so on, until the offset coordinates of the four bottom corners of all grids in the same row as the first grid are calculated; Step 4: taking the grid adjacent to the first grid along the y-axis direction as a new first grid; The probe extending from one of the two mutually perpendicular side surfaces of the new first frame abuts against the adjacent side surface of the first frame, and the probe extending from the other side abuts against the adjacent pool wall; One of the two mutually perpendicular side surfaces of the new first grid is recorded as a new transverse side surface, and the other side surface is recorded as a new longitudinal side surface; Select any two probes extending from the new first longitudinal side surface, and use the probes closer to and farther from the x-axis as the new first probe and the new second probe respectively; select any two probes extending from the new first transverse side surface, and use the probes closer to and farther from the y-axis as the new third probe and the new fourth probe respectively; Repeat steps 2.1-3 until the offset coordinates of the four bottom corners of all grids in the same row as the new first grid are calculated; This process is deduced in this way until the offset coordinates of the four bottom corners of all the grids in the pool are calculated; Step 5: Generate the straight line equation of each bottom side of each grid according to the offset coordinates of the four bottom corners of each grid obtained in step 4; Generate a straight line equation of each pool edge of the pool according to the coordinates of the four corners of the pool in the plane coordinate system; For the four adjacent bottom corners and two adjacent bottom sides of two adjacent grids, the distance values ​​from the four adjacent bottom corners to the adjacent bottom sides are obtained in real time according to the point-to-straight line distance formula, and the minimum distance value is taken as the spacing between the two adjacent grids; For the two bottom corners of one side of the grid adjacent to the pool wall, the distance values ​​between the two bottom corners and the pool wall are obtained in real time according to the point-to-straight-line distance formula, and the minimum distance value is taken as the spacing between the side of the grid and the adjacent pool wall.

2. The method for monitoring the grid spacing of spent fuel storage according to claim 1, characterized in that: The step 2.1 can also calculate the deflection angle α of the first grid according to the following formula (6): （6）； In formula (6), is the vertical distance between the third probe and the fourth probe.

3. The method for monitoring the grid spacing of spent fuel storage according to claim 1, characterized in that: The step 5 is generated in real time by using the mathematical software MATLAB in the host computer.

Images