Structure of a high temperature gas cooled reactor core and method for designing the same

Abstract

The application relates to a structure of a high-temperature gas cooled reactor core and a design method thereof, full consideration is given to the fuel ball position condition in a high-temperature gas cooled reactor compact packing core model, corresponding fuel ball position derivation methods are designed for various special fuel ball position conditions, and a high-temperature gas cooled reactor compact packing core model construction flow is successfully designed and developed. The flow can output the position coordinates of all the fuel balls in the core, and the main functions include: (1) determining and outputting the position coordinates of the random first ball of the core; (2) arranging the fuel balls to the X-axis direction and outputting the position coordinates of the fuel balls; (3) determining the maximum and minimum Y coordinate values that can be arranged by the fuel balls in different layers in the core; (4) arranging the fuel balls to the positive direction and the negative direction of the Y-axis and outputting the position coordinates of the fuel balls.

Description

Technical Field

[0001] This application relates to the field of reactor core design technology, and in particular to the structure and design method of a high-temperature gas-cooled reactor core. Background Technology

[0002] Due to its inherent advantages such as high safety, high power generation efficiency, and economic viability, high-temperature gas-cooled reactor (HTGR) technology is considered one of the most promising technologies to meet the requirements of fourth-generation nuclear energy systems. The pebble bed HTGR has a simple core structure, good irradiation stability of the fuel spheres, deep burnup, and continuous refueling capability, making it a current research hotspot both domestically and internationally.

[0003] The reactor core is a crucial component of a nuclear reactor. In a pebble bed high-temperature gas-cooled reactor, the fuel is spherical, unlike fuel rods which can be placed in a fixed position. Due to their unique shape, the spherical fuel spheres can be stacked in various ways within the core. Different stacking methods affect the total amount of fuel in the core, which in turn may affect relevant physical parameters within the core. Summary of the Invention

[0004] Therefore, it is necessary to provide a structure and design method for a high-temperature gas-cooled reactor core in order to determine the stacking method of fuel spheres and optimize the relevant physical parameters of the core.

[0005] A structure for a high-temperature gas-cooled reactor core, the core comprising:

[0006] Reflector assembly, headspace, fuel ball area, and discharge pipe;

[0007] The headspace is located directly above the fuel sphere area;

[0008] The fuel ball area is cylindrical and has a frustum-shaped bottom; the frustum-shaped bottom is connected to the unloading pipe;

[0009] The reflective assembly includes a top reflective layer, a side reflective layer, and a bottom reflective layer, and is located around the top cavity and the fuel ball area;

[0010] A circular hole is located at the center of the bottom reflector layer; the unloading pipe extends to the outside of the reactor core through the circular hole;

[0011] Within the fuel sphere area, the fuel spheres are stacked in a hierarchical, close-packed manner from bottom to top, as detailed below:

[0012] In each layer, each fuel ball will be tangent to at most 6 fuel balls in its own layer, and at most 3 fuel balls in the layer above and / or the layer below.

[0013] In any odd-numbered layer excluding the first layer, the relationship between the z-coordinate of each fuel sphere and the fuel sphere in the first layer that shares the same x and y coordinates is Z. n=Z1+cd(n-2); where, c is a constant, d is the diameter of the fuel sphere, and n is an odd number; the process of establishing a three-dimensional rectangular coordinate system is as follows: take the midpoint of the axis in the cylindrical fuel sphere area as the origin of the three-dimensional coordinate system, the axis of the cylinder as the z-axis, and the vertical upward direction of the axis as the positive direction of the z-axis; define a radius as the x-axis, and the radial outward direction as the positive direction of the x-axis; define a radius as the y-axis, and the radial outward direction as the positive direction of the y-axis, and establish a three-dimensional rectangular coordinate system;

[0014] In any even-numbered layer excluding the second layer, the relationship between the z-coordinate of each fuel sphere and the fuel sphere in the second layer that shares the same x and y coordinates is Z. m = Z2 + cd(m-2), where m is an even number.

[0015] A design method for a high-temperature gas-cooled reactor core, the method comprising:

[0016] A three-dimensional rectangular coordinate system is constructed. The process of establishing the three-dimensional rectangular coordinate system is as follows: the midpoint of the axis in the cylindrical fuel sphere area is taken as the origin of the three-dimensional coordinate system, the axis of the cylinder is taken as the z-axis, and the vertical upward direction of the axis is taken as the positive direction of the z-axis; one radius of the cylinder is defined as the x-axis, and the radial outward direction is taken as the positive direction of the x-axis; one radius of the cylinder is defined as the y-axis, and the radial outward direction is taken as the positive direction of the y-axis, thus establishing the three-dimensional rectangular coordinate system.

[0017] The location conditions of the first sphere in the reactor core are designed. Based on the location conditions, the radius and height of the cylindrical fuel sphere region, and the diameter of the fuel sphere, the distribution range of all fuel spheres is obtained. The location conditions include: located at the bottom of the fuel sphere region, tangent to the boundary of the fuel sphere region, and not intersecting with the surface of the reflector.

[0018] The z-coordinate of the first sphere in the first layer is obtained based on the distribution range. The x-coordinate and y-coordinate of the first sphere in the first layer are obtained based on the z-coordinate using a random number generator. The position coordinates of the first sphere in the first layer in the reactor core are then randomly obtained. The position coordinates of the first spheres in other fuel sphere layers are calculated based on the position coordinates of the first spheres in the first layer in the reactor core and the stacking method. Thus, the position coordinates of the first spheres in all fuel sphere layers in the reactor core are obtained.

[0019] In each fuel ball layer, based on the coordinates of the first ball of the corresponding layer, combined with the distribution range and the stacking method, and according to the preset position derivation direction of the remaining fuel balls in the same layer as the first ball, the position coordinates of all fuel balls in the corresponding layer are obtained. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a high-temperature gas-cooled reactor core in one embodiment;

[0021] Figure 2 This is a schematic diagram of the fuel sphere region in the reactor core in one embodiment;

[0022] Figure 3 The image shows the fuel ball stacking pattern drawn using the 3DS MaX program in one embodiment; (a) shows the positional relationship of a fuel ball layer with the same Z coordinate consisting of a series of fuel balls with equal Z coordinates in the core, and (b) shows the positional relationship of two different fuel ball layers in the core.

[0023] Figure 4 Here is a tetrahedral unit view in one embodiment; wherein, (a) is a top view of a regular tetrahedron, (b) is a front view of a regular tetrahedron, and (c) is a side view of a regular tetrahedron;

[0024] Figure 5 Here is a tetrahedral structure in one embodiment; wherein, (a) is a structural diagram of the fuel sphere center-to-center line of the tetrahedral structure, and (b) is a top view of the tetrahedral structure;

[0025] Figure 6 This is a flowchart illustrating a design method for a high-temperature gas-cooled reactor core in one embodiment.

[0026] Figure 7 This is a simplified model of the first layer of fuel spheres in one embodiment;

[0027] Figure 8 This is an example of the arrangement of the second layer of fuel balls; where (a) is a first arrangement and (b) is a second arrangement.

[0028] Figure 9 This is an example of the arrangement of the third layer of fuel balls; wherein, (a) is the first arrangement, (b) is the second arrangement, (c) is the third arrangement, and (d) is the fourth arrangement;

[0029] Figure 10 Here is a simplified diagram of the arrangement of fuel balls when the position of the first ball is random in one embodiment; (a) is a first top view, and (b) is a second top view.

[0030] Figure 11 The program code outputs the position of the random first ball in one embodiment;

[0031] Figure 12 Here are some output examples of the program code that outputs the position of the first ball in one embodiment; where (a) is the first output example, (b) is the second output example, (c) is the third output example, and (d) is the fourth output example.

[0032] Figure 13 The following is a sequence of derivation and calculation of the position of fuel spheres in the reactor core in one embodiment; where (a) is process 1, (b) is process 2, and (c) is process 3.

[0033] Figure 14 Output program code for the position of the first row of fuel balls in one embodiment;

[0034] Figure 15 This is a schematic diagram of the second row of first balls arranged in the negative Y-axis direction in one embodiment;

[0035] Figure 16 This is a schematic diagram of the position of the first ball in the second row in one embodiment; wherein, (a) the first ball in the second row is located in the first quadrant, (b) the first ball in the second row is located in the second quadrant, (c) the first ball in the second row is located in the third quadrant, and (d) the first ball in the second row is located in the fourth quadrant;

[0036] Figure 17 Here is a simplified diagram showing the positions of the first ball in the second row and the last ball in the first row in one embodiment; where (a) is the difference of 3 between the first ball and the last ball in the first row, and (b) is the difference of multiples of 3 between the first ball and the last ball in the first row.

[0037] Figure 18 This is a schematic diagram showing that, in one embodiment, the absolute value of the X-coordinate of the first ball in the second row is greater than the absolute value of the X-coordinate of the last ball in the first row.

[0038] Figure 19 This is a selection structure for determining the region where the last ball in the first row is located in one embodiment;

[0039] Figure 20 This is a code snippet from a program that outputs the position of the second row of fuel balls in one embodiment.

[0040] Figure 21 This is a diagram illustrating how to prevent fuel balls from being missed in one embodiment;

[0041] Figure 22 For example, a partial else...if selection structure is set in the program in one embodiment;

[0042] Figure 23 Two different stacking methods of fuel balls in the reactor core are shown in one embodiment; wherein, (a) is the first stacking method and (b) is the second stacking method;

[0043] Figure 24 This is an example of an accumulation structure for calculating the extreme values ​​of the first layer fuel ball Y after the position of the first ball in the core is determined; wherein, (a) is the calculation program for the maximum value of the first layer fuel ball Y, and (b) is the calculation program for the minimum value of the first layer fuel ball Y.

[0044] Figure 25 This is a schematic diagram of the fuel ball arrangement in one embodiment without the negative second row of first balls;

[0045] Figure 26This is a schematic diagram of the position of the first ball in the second row of the negative row in one embodiment; wherein, (a) the first ball in the second row of the negative row is located in the first quadrant, (b) the first ball in the second row of the negative row is located in the second quadrant, (c) the first ball in the second row of the negative row is located in the third quadrant, and (d) the first ball in the second row of the negative row is located in the fourth quadrant;

[0046] Figure 27 Here is a simplified diagram showing the positions of the first ball in the second row and the last ball in the first row in one embodiment; where (a) is the difference of 3 between the first ball and the last ball in the first row, and (b) is the difference of multiples of 3 between the first ball and the last ball in the first row.

[0047] Figure 28 This is a schematic diagram showing that, in one embodiment, the absolute value of the X-coordinate of the first ball in the second negative row is greater than the absolute value of the X-coordinate of the last ball in the first row.

[0048] Figure 29 This is a flowchart illustrating the procedure for positioning the second row of fuel balls within the reactor core in one embodiment. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0050] In one embodiment, such as Figure 1 As shown, a structure for a high-temperature gas-cooled reactor core is provided, the core comprising:

[0051] Reflector assembly, headspace, fuel ball area, and discharge pipe;

[0052] The headspace is located directly above the fuel sphere area;

[0053] The fuel ball area is cylindrical and has a frustum-shaped bottom; the frustum-shaped bottom is connected to the unloading pipe;

[0054] The reflective assembly includes a top reflective layer, a side reflective layer, and a bottom reflective layer, and is located around the top cavity and the fuel ball area;

[0055] A circular hole is located at the center of the bottom reflector layer; the unloading pipe extends to the outside of the core through the circular hole.

[0056] As shown in Table 1, some structural parameters of the reactor core are provided in one embodiment.

[0057] Table 1. Some structural parameters of the reactor core

[0058]

[0059] This work primarily focuses on modeling the fuel sphere region of the reactor core. The fuel sphere region is shaped like a cylinder, with the midpoint of the cylinder's central axis as the origin of the three-dimensional coordinate system. The cylinder's axis is defined as the Z-axis, with the vertically upward direction being the positive Z-axis. A radius is defined as the X-axis, with the radial direction outward being the positive X-axis. Subsequently, the Y-axis is determined, with the radial direction outward being the positive Y-axis, establishing a three-dimensional Cartesian coordinate system for subsequent core modeling and calculations. The fuel sphere region of the reactor core is drawn using the 3DS Max program as shown below. Figure 2 As shown.

[0060] Within the fuel sphere area, the fuel spheres are stacked in a hierarchical, close-packed manner from bottom to top, as detailed below:

[0061] In each layer, each fuel ball will be tangent to at most 6 fuel balls in its own layer, and at most 3 fuel balls in the layer above and / or the layer below. For example... Figure 3 As shown, the fuel sphere stacking is presented using the 3DS MaX program. (a) shows the positional relationship of a fuel sphere layer with the same Z coordinate, consisting of a series of fuel spheres with equal Z coordinates in the core, and (b) shows the positional relationship of two different fuel sphere layers in the core.

[0062] In any odd-numbered layer excluding the first layer, the relationship between the z-coordinate of each fuel sphere and the fuel sphere in the first layer that shares the same x and y coordinates is Z. n =Z1+cd(n-2), where c is a constant, d is the diameter of the fuel ball, and n is an odd number.

[0063] In any even-numbered layer excluding the second layer, the relationship between the z-coordinate of each fuel sphere and the fuel sphere in the second layer that shares the same x and y coordinates is Z. m = Z2 + cd(m-2), where m is an even number.

[0064] In one embodiment, mixed fuel balls are stacked in the fuel ball region; in each mixed fuel ball, the volume ratio of fuel to graphite is 0.57:0.43. For the reactor core to operate at rated power and possess suitable residual reactivity, the fuel balls and graphite balls within the core must be uniformly mixed in a 57:43 loading ratio. Due to the large number of fuel balls and graphite balls in the core, this design replaces the original fuel balls and graphite balls with mixed fuel balls containing fuel and graphite (volume ratio of 0.57:0.43).

[0065] In one embodiment, the fuel is a ternary isotropic coated fuel particle.

[0066] In one embodiment, the coated fuel particles include a coated fuel core and a coating layer.

[0067] The reactor core uses helium as the coolant and employs a design with spherical fuel and spherical moderators. The initial loading uses a fuel scheme that uniformly mixes fuel spheres and graphite spheres. Each fuel sphere consists of "TRISO" type coated fuel particles uniformly dispersed within a graphite matrix, with approximately 8335 coated fuel particles per sphere. Relevant parameters for the core fuel spheres and graphite spheres are shown in Table 2.

[0068] Table 2. Relevant parameters of reactor core fuel balls and graphite balls.

[0069]

[0070]

[0071] Taking a fuel ball with a diameter of 6cm as an example, combined with Figure 3 As shown in the fuel sphere stacking diagram, any four interlocking fuel spheres in the reactor core can form a [structure] such as [structure]. Figure 4 The diagram shows a small tetrahedral structural unit, where (a), (b), and (c) are the top view, front view, and side view of the tetrahedron, respectively. The lines connecting the centers of the fuel spheres within the tetrahedral structural unit can form a pattern as shown below. Figure 5 The diagram shows a regular tetrahedron, where (a) and (b) are the structural diagram of the fuel spheres connected by the center line and the top view of the regular tetrahedron structure, respectively.

[0072] Figure 5 In the diagram, fuel spheres 1, 2, and 3 have the same Z-coordinate and belong to the same fuel sphere layer; fuel spheres 1 and 2 have the same Y-coordinate and belong to the same fuel sphere row; fuel sphere 1 is tangent to fuel spheres 2 and 3 simultaneously, and the line connecting their centers is... Figure 5 (b) shows an equilateral triangle; fuel sphere 4 is simultaneously tangent to fuel spheres 1, 2, and 3, and the lines connecting their centers form a triangle as shown in Figure 1. Figure 5 (a) shows a regular tetrahedron.

[0073] Taking fuel ball No. 1 as the reference point, the X coordinates of the other three fuel balls are calculated as shown in equations (3-1) to (3-3); the Y coordinates of the other three fuel balls are calculated as shown in equations (3-4) to (3-6); and the Z coordinate of fuel ball No. 4 is shown in equation (3-7).

[0074] X2 = X1 + 6 (3-1)

[0075] X3 = X1 + 3 (3-2)

[0076] X4 = X1 + 3 (3-3)

[0077] Y2 = Y1 (3-4)

[0078] Y3 = Y1 - 5.2 (3-5)

[0079] Y4 = Y1 - 1.7 (3-6)

[0080] Z4 = Z1 + 4.9 (3-7)

[0081] It can be seen that the Z coordinates of fuel balls in different fuel ball layers in the reactor core differ by a multiple of 5.2; the fuel ball coordinates in the same Z layer have the following rules: (1) the fuel balls have the same Z coordinate; (2) the X coordinates of fuel balls on the same Y axis differ by a multiple of 6; (3) the X coordinates of fuel balls in each fuel ball row differ by a multiple of 5.2.

[0082] In one embodiment, such as Figure 6 As shown, a design method for a high-temperature gas-cooled reactor core is provided, the method comprising the following steps:

[0083] Step 602: Construct a three-dimensional rectangular coordinate system.

[0084] The process of establishing a three-dimensional rectangular coordinate system is as follows: take the midpoint of the axis in the cylindrical fuel sphere area as the origin of the three-dimensional coordinate system, the axis of the cylinder as the z-axis, and the upward vertical direction of the axis as the positive direction of the z-axis; define one radius of the cylinder as the x-axis, and the outward radial direction as the positive direction of the x-axis; define one radius of the cylinder as the y-axis, and the outward radial direction as the positive direction of the y-axis, and establish a three-dimensional rectangular coordinate system.

[0085] Step 604: Design the position conditions of the first sphere in the first layer of the reactor core. Based on the position conditions, the radius and height of the cylindrical fuel sphere area, and the diameter of the fuel sphere, obtain the distribution range of all fuel spheres.

[0086] Location conditions include: being located at the bottom of the fuel sphere region, being tangent to the boundary of the fuel sphere region, and not intersecting with the surface of the reflector.

[0087] Step 606: Obtain the z-coordinate of the first sphere of the first layer according to the distribution range, and use a random number generator to obtain the x and y coordinates of the first sphere of the first layer according to the z-coordinate. Thus, randomly obtain the position coordinates of the first sphere of the first layer in the core. Calculate the position coordinates of the first spheres of other fuel spheres according to the position coordinates of the first spheres of the first layer in the core and the stacking method. Thus, obtain the coordinates of the first spheres of all fuel spheres in the core.

[0088] Step 608: In each fuel ball layer, based on the coordinates of the first ball of the corresponding layer, combined with the distribution range and stacking method, and according to the preset position derivation direction of the remaining fuel balls in the same layer as the first ball, the position coordinates of all fuel balls in the corresponding layer are obtained.

[0089] In one embodiment, within each fuel sphere layer, based on the coordinates of the first sphere of the corresponding layer, combined with the distribution range and stacking method, and following a preset derivation direction of the remaining fuel spheres in the same layer as the first sphere, the position coordinates of all fuel spheres in the corresponding layer are obtained, including:

[0090] In each fuel sphere layer, based on the coordinates of the first sphere of the corresponding layer, the first row of fuel spheres with the same y coordinate as the first sphere of the corresponding layer is arranged along the x-axis, and the position coordinates of the first row of fuel spheres of the corresponding layer are output.

[0091] After the first row of fuel balls is arranged, the next row of fuel balls is arranged in the positive y-axis direction and the position coordinates of the next row of fuel balls are output.

[0092] After the fuel balls are arranged in the positive y-axis direction, return to the last ball position of the first row of fuel balls, start arranging the fuel balls in the negative y-axis direction from the last ball position, and output the position coordinates of the fuel balls;

[0093] The coordinates of the aforementioned fuel balls are all within the distribution range and conform to the aforementioned stacking method.

[0094] In one embodiment, the method further includes:

[0095] In the first fuel sphere layer, the maximum and minimum values ​​of the y-coordinate of the corresponding fuel sphere are determined based on the coordinates of the first sphere.

[0096] After the first row of fuel balls is arranged, if the y-coordinate of the next row of fuel balls in the positive y-axis direction is greater than the maximum value, then return directly to the last position of the first row of fuel balls, start arranging fuel balls in the negative y-axis direction from the last position, and output the position coordinates of the fuel balls.

[0097] In one embodiment, determining the maximum value of the y-coordinate of the corresponding fuel sphere based on the first sphere coordinates includes:

[0098] Calculate the radius difference between the radius of the cylindrical fuel zone and the radius of the fuel sphere, and calculate the first difference between the radius difference and the y-coordinate of the first sphere of the corresponding layer;

[0099] When the first difference is less than When the first sphere's y-coordinate is used, the maximum value of the first layer of fuel sphere's y-coordinate is directly taken; where R is the radius of the fuel sphere.

[0100] When the first difference is not less than At that time, the y-coordinate of the first ball is compared with... The sum of these values ​​is used as the initial value for the maximum y-coordinate. In each iteration, the first difference is calculated as a multiple of the initial value and an integer multiple thereof. The difference between the sums is used to obtain a new first difference. The iteration continues until the first difference is less than 0, at which point the iteration terminates and outputs the initial value and its integer multiple obtained in the last iteration. The sum of , calculate the sum and The difference is used to obtain the maximum value of the y-coordinate of the first layer of fuel spheres.

[0101] In one embodiment, determining the minimum y-coordinate of the corresponding fuel sphere based on the first sphere coordinates includes:

[0102] Calculate the radius difference between the radius of the cylindrical fuel zone and the radius of the fuel sphere, and calculate the first sum of the radius difference and the y-coordinate of the first sphere of the corresponding layer;

[0103] When the first sum is less than When the first sphere's y-coordinate is used as the minimum y-coordinate of the first layer of fuel spheres, R is the radius of the fuel sphere.

[0104] When the first sum is not less than At that time, the y-coordinate of the first ball is compared with... The difference is used as the initial value for the minimum y-coordinate. In each iteration, the first sum is calculated as the sum of the initial value and an integer multiple thereof. The sum of the differences is used to obtain a new first sum. The iteration terminates when the first sum is less than 0, and the initial value and its integer multiple obtained in the last iteration are output. The difference, calculate the difference and The sum of these values ​​yields the minimum y-coordinate of the first layer of fuel spheres.

[0105] Taking a fuel ball with a diameter of 6cm as an example, the design method in this application is described in detail.

[0106] Because the fuel balls are tightly packed in the reactor core, once the position of the first layer of fuel balls is determined, the second layer of fuel balls must be tangent to each other within the same layer, and also tangent to the fuel balls in contact with the layers above and below. Simplifying the first layer of fuel balls, we retain only the smallest unit consisting of 7 fuel balls, such as... Figure 7 .

[0107] When arranging the second layer of fuel spheres, they must be tangent to the first layer. That is, when arranging the second layer of fuel spheres, the fuel spheres are placed on... Figure 7 The gaps formed by the first layer of fuel spheres allow each fuel sphere in the second layer to interact with three fuel spheres in the first layer, as shown in the diagram. Figure 4 The tetrahedral structure shown.

[0108] Depend on Figure 7 As shown, the first layer of fuel balls, consisting of 7 fuel balls, has 6 empty slots for placing fuel balls, but the maximum number of fuel balls that can be placed in the second layer above it is 3. This means that once the positions of the first layer of fuel balls are determined, there are two options for the arrangement of the second layer of fuel balls, such as... Figure 8 As shown. Figure 8 The arrangement of the second layer of fuel balls shown in (a) can be regarded as... Figure 7 The AFG in the middle is obtained by increasing the Z coordinate by 4.9 and decreasing the Y coordinate by 3.5. Figure 8 The arrangement of the second layer of fuel balls shown in (b) can be regarded as... Figure 7 The DCG was obtained by increasing the Z coordinate by 4.9 and the Y coordinate by 1.7.

[0109] The equivalent height of each fuel sphere in the reactor core is 4.9 cm. When the fuel spheres are tightly packed in the core, there are 36 layers of fuel spheres. If the fuel spheres are tightly packed in the core in a completely random manner, the arrangement of the third layer of fuel spheres will have 4 possible arrangements due to the randomness of the arrangement of the second layer, such as... Figure 9 As shown.

[0110] Based on the above analysis, there will be 2 possible arrangements of fuel spheres in the entire reactor core. 35 kind.

[0111] Given that the position of the first layer of fuel spheres is determined, such as Figure 9 (c) The third layer of fuel spheres can be considered as a mirror image of the first layer of fuel spheres along the Z-axis. That is, each fuel sphere in the third layer corresponds to one fuel sphere in the first layer, with the same X and Y coordinates, only differing by a multiple of 4.9 in the Z-coordinate. This work will adopt the following... Figure 9 (c) Arrange the fuel balls in the core in the form of (c), where any fuel ball (X) in any nth (n is an odd number and n∈[3,35]) layer other than the first layer. n ,Y n Z n It can be seen as being obtained by transforming the corresponding fuel ball (X1,Y1,Z1) in the first layer through equations (3-9), (3-10), and (3-11).

[0112] X n =X1 (3-9)

[0113] Y n =Y1 (3-10)

[0114] Z n =Z1+9.8(n-2) (3-11)

[0115] Figure 9 In (c), the second layer of fuel spheres is described in the 3DS MaX program as a clone of the first layer of fuel spheres, with the X coordinate unchanged, the Y coordinate decreased by 3.5, and the Z coordinate increased by 4.9. Fuel spheres in different even-numbered layers of the reactor core also satisfy the positional pattern of fuel spheres in different odd-numbered layers. That is, any fuel sphere (X...) in any m-th (m is an even number and m∈[4,36]) layer other than the second layer... m ,Y m Z m It can be seen as being obtained by transforming the corresponding fuel ball (X2,Y2,Z2) in the first layer through equations (3-11), (3-12).

[0116] X m =X2 (3-13)

[0117] Y m =Y2 (3-13)

[0118] Z m =Z2+9.8(m-2) (3-14)

[0119] To ensure that the model building program constructed in this work does not lose generality for closely packed reactor core models and conforms to actual conditions, the position of the first sphere in the core is set to random for subsequent algorithm analysis and program construction. The position of the first sphere should satisfy: (1) located at the bottom of the core; (2) tangent to the core boundary. Different positions of the first sphere will have a certain impact on the number of fuel spheres in the core, such as Figure 10 As shown. In this design, the fuel spheres do not intersect with the reflector surface; therefore, the coordinates of all fuel spheres within the reactor core must satisfy:

[0120] Z∈[-87,87] (3-15)

[0121] X 2 +Y 2 ≤87 2 (3-16)

[0122] from Figure 10 It can be seen that when the position of the first ball is random, different positions of the first ball will have a certain impact on the total number of fuel balls in the core.

[0123] This work will be based on a C language program, using functions such as srand to construct a program for determining the random position of the first ball. The specific steps include: (1) using the system time as a seed, randomly obtaining a number between 0 and 360 as the angle; (2) using 87 as the radius, determining the X and Y coordinates of the first ball through the obtained angle and the sine and cosine functions; (3) using -87 as the Z coordinate of the first ball, and outputting the position coordinates of the first ball. The code for the random first ball position output program is as follows: Figure 11 As shown, some of the output results are as follows: Figure 12 As shown, where Figure 12 (a), (b), (c) and (d) are all output examples.

[0124] By running the random first ball program multiple times, the position of the first ball in the core is randomly obtained as (44.8, 74.6, -87), and the coordinates of the first ball of the second fuel ball in the core are obtained as (44.8, 71.1, -82.1). From this, the coordinates of the first ball of all fuel balls can be obtained.

[0125] After obtaining the position of the first sphere in the reactor core, an algorithm for deriving the positions of the remaining fuel spheres in the same layer as the first sphere was designed. The derivation process is as follows: Figure 13The process is divided into three steps: (1) As shown Figure 13 (a) Based on the position of the first sphere, arrange the first row of fuel spheres in the core along the X-axis, which have the same Y-coordinate as the first sphere, and output the position coordinates of the first row of fuel spheres in the core; (2) As Figure 13 (b) After the first row of fuel balls is arranged, the next row of fuel balls is arranged in the positive Y-axis direction and the position coordinates of the fuel balls are output; (3) such as Figure 13 (c) After the fuel balls are arranged in the positive Y-axis direction, return to the last fuel ball position of the first row of fuel balls, start arranging fuel balls in the negative Y-axis direction and output the position coordinates of the fuel balls.

[0126] When arranging the first layer of fuel balls, all fuel balls in the same row have the same Y-coordinate, and their X-coordinates differ by a multiple of 6. This rule applies to fuel balls in the same row when arranged in either the positive or negative Y-axis direction. Simultaneously, the coordinates of each fuel ball within the core must satisfy the requirements of equations (3-13) and (3-14). After calculating the coordinates of each fuel ball, equation (3-14) must be used to verify whether it meets the specified geometric boundary conditions. During the program design process, a variable 'e' is set to determine whether the fuel ball coordinates satisfy the core's geometric conditions.

[0127] e = X 2 +Y 2 (3-17)

[0128] The calculated value of e is 87.07. This is because the calculation of fuel ball coordinates involves a decimal part during the program design process. In order to prevent the rounding of the decimal part from causing changes in the e value during the calculation, some fuel balls would be discarded during the calculation process, resulting in a change in the total number of fuel balls in the reactor core.

[0129] To ensure the universality of the algorithm and program designed in this work, the following design work will proceed with the subsequent program construction work under the condition that the position of the first ball is not determined. Figure 12 The output example shows that the position of the first sphere is located in eight regions: the first quadrant, the second quadrant, the third quadrant, the fourth quadrant, and the positive and negative half-axis of X and Y. When arranging the first row of fuel spheres, a selection structure for the first sphere's X-coordinate needs to be set to ensure that the position of the first row of fuel spheres is correctly output regardless of the first sphere's initial position. The code for outputting the first row of fuel spheres is as follows: Figure 14 As shown.

[0130] according to Figure 13 After the positions of all fuel balls in the first row are derived, the arrangement of the second row of fuel balls begins in the positive Y-axis direction. Starting with the last fuel ball in the first row (hereinafter referred to as the last ball of the first row), according to... Figure 7The simplified model of the first layer of fuel spheres shown can be used to calculate the coordinates of the first sphere of the second row of fuel spheres (hereinafter referred to as the first sphere of the second row). That is, the X coordinate of the first sphere of the second row differs from that of the last sphere of the first row by a multiple of 3, and the Y coordinate of the first sphere of the second row is 5.2 greater than that of the last sphere of the first row.

[0131] When calculating the position of the first ball in the second row of fuel balls, since the position of the first row of fuel balls is determined by the first ball, there is a special case regarding the arrangement of the second row of fuel balls when the position of the first ball is different. After the position of the first row of fuel balls is determined, the fuel balls cannot continue to be arranged in the positive Y-axis direction, such as... Figure 15 As shown. Besides this case, the possible areas for the first ball in the second row include the first, second, third, and fourth quadrants and each coordinate axis, and will appear as follows. Figure 16 The four scenarios are shown.

[0132] by Figure 16 (a) and Figure 16 (b) Taking this as an example, when the Y-coordinate of the first ball in the second row is greater than or equal to zero, it can be analyzed in two cases. One is as follows: Figure 17 The two cases shown are: firstly, the absolute value of the X-coordinate of the first ball in the second row is less than the absolute value of the X-coordinate of the last ball in the first row; secondly, as shown... Figure 18 As shown, the absolute value of the X-coordinate of the first ball in the second row is greater than the absolute value of the X-coordinate of the last ball in the first row.

[0133] Based on the above analysis, due to the different positions of the last ball in the first row, there are a total of 6 ways to deduce the position of the first ball in the second row. In this work, before arranging the second layer of fuel balls, the position of the last ball in the first row is first determined, and a method is established as follows: Figure 19 The selection structure shown.

[0134] In order to make the program like Figure 17 In the case of [missing information], output the correct coordinates of the second row of fuel spheres, and use the already set variable 'e' to prevent the fuel spheres from exceeding the core boundary. Part of the program code is as follows: Figure 20 As shown; in order to make the program as Figure 18 In the case of [condition], output the coordinates of the second-layer fuel sphere, set as follows: Figure 21 The "trial fuel ball" and multiple "else...if" selection structures shown prevent fuel balls from being missed. Some code snippets are as follows: Figure 22 As shown.

[0135] After the second row of fuel balls is arranged, it will be as follows: Figure 13 The process continues with the arrangement of the next row of fuel balls. To make the program more concise, a do...while loop structure is used to enable automatic line breaks. Since this work sets the fuel balls to be arranged in a full row along the X-axis before moving to the Y-axis, the value of Y needs to be restricted when using the do...while statement. Figure 23 As shown, due to the different positions of the first spheres within the reactor core, the maximum and minimum values ​​of the Y-coordinate of the fuel spheres in the same layer are not fixed.

[0136] This work sets up the following: Figure 24 The cumulative structure shown is used to calculate the extreme value of the first fuel ball Y after the position of the first ball in the core is determined, where (a) is the calculation program for the maximum value of the first fuel ball Y, and (b) is the calculation program for the minimum value of the first fuel ball Y.

[0137] After the fuel balls are aligned in the positive Y-axis direction, as follows: Figure 13 (c) shows the jump back to the last ball of the first row. The coordinates of the first ball of the second row of fuel (hereinafter referred to as the negative second row) are calculated when the fuel balls are arranged in the negative Y-axis direction. When the fuel balls are arranged in the negative Y-axis direction, a special case arises because the position of the last ball of the first row is uncertain. That is, after the position of the first row of fuel balls is determined, the fuel balls cannot continue to be arranged in the positive Y-axis direction, such as... Figure 25 As shown. Besides this case, the possible areas for the first ball in the negative second row include the first, second, third, and fourth quadrants and each coordinate axis, and will appear as follows. Figure 26 The four scenarios are shown.

[0138] by Figure 26 (c) and Figure 26 (d) Taking this as an example, when the Y-coordinate of the first ball in the second row is less than or equal to zero, it can be analyzed in two cases. One is as follows: Figure 27 The two cases shown are: firstly, the absolute value of the X-coordinate of the first ball in the second row is less than the absolute value of the X-coordinate of the last ball in the first row; secondly, as shown... Figure 28 As shown, the absolute value of the X-coordinate of the first ball in the second negative row is greater than the absolute value of the X-coordinate of the last ball in the first row.

[0139] The problems that arise when the fuel balls are aligned in the negative Y-axis direction can be largely resolved by utilizing the corresponding countermeasures and algorithms previously established for addressing the unknown situation of fuel balls being aligned in the positive Y-axis direction.

[0140] Once the position of the first sphere in the reactor core is determined, the coordinates of the first fuel sphere in the second layer can be obtained from it. For example... Figure 29 As shown, since the arrangement of the second layer of fuel balls is similar to that of the first layer, when arranging the second layer of fuel balls, the position coordinates of the second layer of fuel balls can be output directly using the position output program of the first layer of fuel balls based on the position of the first ball of the second layer.

[0141] After the positions of the first and second layers of fuel balls are arranged, according to the positional relationships of fuel balls between different odd-numbered layers and different even-numbered layers shown in equations (3-7) to (3-12), the do...while loop structure provided by the C language is used to make the model building program continue to arrange the remaining 34 layers of fuel balls in the core and output their position coordinates.

[0142] In designing the fuel sphere location output program for the reactor core, this work comprehensively considered various special arrangements that might occur when fuel spheres are tightly packed within the core, and set up algorithms to handle these special cases. This ensured, to the greatest extent possible, that the fuel sphere coordinates output by the model building program were error-free and complete. Table 3 shows the random first sphere coordinates and the total number of fuel spheres in the core obtained after multiple runs of the model building program.

[0143] Table 3 Output results of the model building program

[0144]

[0145]

[0146] The first sphere coordinates selected in this work are (44.8, 74.6, -87). The total number of fuel spheres in the core is 27522, and the core space fill rate is 67.96%. The standard deviation of the total number of fuel spheres at different first sphere positions is calculated to be 251, with a coefficient of variation of 0.9%. This indicates that the different first sphere positions have a relatively small impact on the total number of fuel spheres in the core, proving that it is feasible to construct a close-packed core model using a random first sphere approach.

[0147] This work fully considers the fuel ball positions in the close-packed core model of a high-temperature gas-cooled reactor (HTGR), and designs corresponding fuel ball position algorithms for various special fuel ball position situations. A successful HTGR close-packed core model construction program was developed. This program can output the position coordinates of all fuel balls in the core. Its main functions include: (1) determining and outputting the position coordinates of the first random sphere in the core; (2) arranging fuel balls along the X-axis and outputting their position coordinates; (3) determining the maximum and minimum Y-coordinate values ​​that can be used to arrange fuel balls in different layers within the core; and (4) arranging fuel balls along the positive and negative Y-axis directions and outputting their position coordinates.

[0148] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0149] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A structure for a high-temperature gas-cooled reactor core, characterized in that, include: Reflector assembly, headspace, fuel ball area, and discharge pipe; The headspace is located directly above the fuel ball area; The fuel ball area is cylindrical and has a frustum bottom; the frustum bottom is connected to the unloading pipe; The reflective assembly includes a top reflective layer, a side reflective layer, and a bottom reflective layer, and is located around the top cavity and the fuel ball area; The bottom reflective layer has a circular hole at its center; the unloading pipe extends through the circular hole to the outside of the high-temperature gas-cooled reactor core. Within the fuel sphere region, the fuel spheres are stacked in a hierarchical, close-packed manner from bottom to top, as detailed below: In each layer, each fuel ball will be tangent to at most 6 fuel balls in its own layer, and at most 3 fuel balls in the layer above and / or the layer below. In any odd-numbered layer excluding the first layer, the relationship between the z-coordinate of each fuel sphere and the fuel sphere in the first layer that shares the same x and y coordinates is as follows: Where c is a constant, d is the diameter of the fuel sphere, and n is an odd number; the process of establishing the three-dimensional rectangular coordinate system is as follows: take the midpoint of the axis in the cylindrical fuel sphere area as the origin of the three-dimensional coordinate system, the axis of the cylinder as the z-axis, and the vertical upward direction of the axis as the positive direction of the z-axis; define a radius as the x-axis, and the radial outward direction as the positive direction of the x-axis; define a radius as the y-axis, and the radial outward direction as the positive direction of the y-axis, and establish the three-dimensional rectangular coordinate system; In any even-numbered layer excluding the second layer, the relationship between the z-coordinate of each fuel sphere and the fuel sphere in the second layer that shares the same x and y coordinates is as follows: m is an even number.

2. The structure of the high-temperature gas-cooled reactor core according to claim 1, characterized in that, Mixed fuel balls are stacked in the fuel ball area; in each mixed fuel ball, the volume ratio of fuel to graphite is 0.57:0.

43.

3. The structure of the high-temperature gas-cooled reactor core according to claim 2, characterized in that, The fuel is a ternary isotropic coated fuel particle.

4. The structure of the high-temperature gas-cooled reactor core according to claim 3, characterized in that, The coated fuel particles include a coated fuel core and a coating layer.

5. A design method for the structure of a high-temperature gas-cooled reactor core as described in any one of claims 1 to 4, characterized in that, The method includes: A three-dimensional rectangular coordinate system is constructed. The process of establishing the three-dimensional rectangular coordinate system is as follows: the midpoint of the axis in the cylindrical fuel sphere area is taken as the origin of the three-dimensional coordinate system, the axis of the cylinder is taken as the z-axis, and the vertical upward direction of the axis is taken as the positive direction of the z-axis; one radius of the cylinder is defined as the x-axis, and the radial outward direction is taken as the positive direction of the x-axis; one radius of the cylinder is defined as the y-axis, and the radial outward direction is taken as the positive direction of the y-axis, thus establishing the three-dimensional rectangular coordinate system. The location conditions of the first sphere in the structure of the high-temperature gas-cooled reactor core are designed. Based on the location conditions, the radius and height of the cylindrical fuel sphere area, and the diameter of the fuel sphere, the distribution range of all fuel spheres is obtained. The location conditions include: located at the bottom of the fuel sphere area, tangent to the boundary of the fuel sphere area, and not intersecting with the surface of the reflector. The z-coordinate of the first sphere in the first layer is obtained based on the distribution range. The x-coordinate and y-coordinate of the first sphere in the first layer are obtained based on the z-coordinate using a random number generator. The position coordinates of the first sphere in the first layer within the structure of the high-temperature gas-cooled reactor core are then randomly obtained. The position coordinates of the first spheres in other fuel spheres are calculated based on the position coordinates of the first spheres in the first layer within the structure of the high-temperature gas-cooled reactor core and the stacking method. Thus, the position coordinates of the first spheres in all fuel spheres within the structure of the high-temperature gas-cooled reactor core are obtained. In each fuel ball layer, based on the coordinates of the first ball of the corresponding layer, combined with the distribution range and the stacking method, and according to the preset position derivation direction of the remaining fuel balls in the same layer as the first ball, the position coordinates of all fuel balls in the corresponding layer are obtained.

6. A design method for the structure of a high-temperature gas-cooled reactor core as described in claim 5, characterized in that, In each fuel sphere layer, based on the coordinates of the first sphere of the corresponding layer, combined with the distribution range and the stacking method, and following the preset derivation direction of the remaining fuel spheres in the same layer as the first sphere, the position coordinates of all fuel spheres in the corresponding layer are obtained, including: In each fuel sphere layer, based on the coordinates of the first sphere of the corresponding layer, the first row of fuel spheres with the same y coordinate as the first sphere of the corresponding layer is arranged along the x-axis, and the position coordinates of the first row of fuel spheres of the corresponding layer are output. After the first row of fuel balls is arranged, the next row of fuel balls is arranged in the positive y-axis direction and the position coordinates of the next row of fuel balls are output. After the fuel balls are arranged in the positive y-axis direction, return to the last ball position of the first row of fuel balls, and start arranging the fuel balls in the negative y-axis direction from the last ball position and output the position coordinates of the fuel balls; The coordinates of the aforementioned fuel balls are all within the distribution range and conform to the stacking method.

7. A design method for the structure of a high-temperature gas-cooled reactor core as described in claim 6, characterized in that, The method further includes: In the first fuel sphere layer, the maximum and minimum values ​​of the y-coordinate of the corresponding fuel sphere are determined based on the coordinates of the first sphere. After the first row of fuel balls is arranged, if the y-coordinate of the next row of fuel balls in the positive y-axis direction is greater than the maximum value, then return directly to the last ball position of the first row of fuel balls, and start arranging fuel balls in the negative y-axis direction from the last ball position and output the position coordinates of the fuel balls.

8. A design method for the structure of a high-temperature gas-cooled reactor core as described in claim 7, characterized in that, The maximum value of the y-coordinate of the corresponding fuel sphere is determined based on the coordinates of the first sphere, including: Calculate the radius difference between the radius of the cylindrical fuel zone and the radius of the fuel sphere, and calculate the first difference between the radius difference and the y-coordinate of the first sphere of the corresponding layer; When the first difference is less than When R is the radius of the fuel sphere, the y-coordinate of the first sphere is directly taken as the maximum value of the y-coordinate of the first layer of fuel spheres; where R is the radius of the fuel sphere. When the first difference is not less than When R, the y-coordinate of the first ball is compared with... The sum of R is used as the initial value for the maximum value of the y-coordinate. In each iteration, the first difference is calculated as a multiple of the initial value and an integer multiple thereof. The difference between the sums of R is used to obtain a new first difference. The iteration continues until the first difference is less than 0, at which point the iteration terminates, and the initial value and its integer multiple obtained in the last iteration are output. The sum of R, calculate the sum and The difference in R is used to obtain the maximum value of the y-coordinate of the first layer of fuel spheres.

9. A design method for the structure of a high-temperature gas-cooled reactor core as described in claim 7, characterized in that, The minimum y-coordinate of the corresponding fuel sphere is determined based on the coordinates of the first sphere, including: Calculate the radius difference between the radius of the cylindrical fuel zone and the radius of the fuel sphere, and calculate the first sum of the radius difference and the y-coordinate of the first sphere of the corresponding layer; When the first sum is less than When R is the radius of the fuel sphere, the y-coordinate of the first sphere is directly used as the minimum y-coordinate of the first layer of fuel spheres; where R is the radius of the fuel sphere. When the first sum is not less than When R, the y-coordinate of the first ball is compared with... The difference in R is used as the initial value for the minimum y-coordinate. In each iteration, the first sum is calculated as the sum of the initial value and an integer multiple thereof. The sum of the differences of R is used to obtain a new first sum. The iteration terminates when the first sum is less than 0, and the initial value and its integer multiple obtained in the last iteration are output. The difference of R, calculate the difference with The sum of R gives the minimum y-coordinate of the first fuel sphere.

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