Method and system for calculating diffusion coefficient of homogenized neutrons containing control rod reflecting layer

Abstract

The invention discloses a method and a system for calculating a uniform neutron diffusion coefficient of a reflecting layer containing a control rod, and relates to the technical field of nuclear reactor physical calculation, and the method comprises the following steps: calculating uniform sections of a reflecting layer and a control rod of a pebble-bed high-temperature gas cooled reactor by using a component calculation program; according to the model grid division condition, a reflecting layer grid containing a control rod pore channel is equivalent to a square grid, and the side length of the grid and the pore channel area share are calculated; according to the control rod structure in the pore channel, probability expressions of the equivalent reflecting layer grids before and after the neutron beam penetrates through the homogenization are obtained respectively; and based on a penetration probability conservation theory, obtaining a reflection layer neutron diffusion coefficient calculation formula considering the control rod structure. And the absorption effect of the control rod in the pore channel on neutrons can be effectively considered, so that the precision of subsequent reactor core neutronics calculation is improved.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear reactor physics calculation, in particular to a method and system for calculating a homogenized neutron diffusion coefficient of a control rod reflector layer. Background Art

[0002] The side reflector of the pebble bed high temperature gas-cooled reactor is arranged with many channels, such as control rod channels, absorption ball channels and coolant channels. Since the channels are mainly gas, there is almost no reaction to neutrons, so the mean free path of neutrons in the channels is much larger than the mean free path of non-porous media, showing a strong neutron leakage non-uniformity, namely the neutron flow effect. Therefore, the neutron flow effect needs to be corrected when calculating the homogenized neutron diffusion coefficient of the porous structure. The prior art adopts the penetration probability conservation theory, and derives the calculation formula of the homogenized neutron diffusion coefficient of the reflector containing channels based on the empty channel situation, and corrects the neutron flow effect of the reflector containing empty channels.

[0003] The control rods are mostly made of inner and outer control rod sleeve structures, and the outer control rod has a downward insertion limit. Therefore, in actual operation, the outer control rod will remain in the same position while the inner control rod continues to be inserted downward, and the inner control rod will be separated from the outer control rod. If a reflector layer with a height of control rod holes is taken in the axial direction, there will be three combinations of control rods inside: 1) only inner control rods, 2) only outer control rods, and 3) inner control rods and outer control rods coexist. The existing technology does not consider the absorption of neutrons by the control rods inside the hole when correcting the neutron flow effect of the reflector hole, so it is not suitable for calculating the homogenized neutron diffusion coefficient of the reflector layer containing control rods in the hole. Summary of the invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by the present invention is: how to calculate the homogenized neutron diffusion coefficient of the reflection layer containing the control rods in the channel.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for calculating the homogenized neutron diffusion coefficient of a reflector layer containing control rods, comprising: using a component calculation program to calculate the homogenized cross-section of the reflector layer and control rods of a pebble bed high temperature gas-cooled reactor; according to the model grid division situation, the reflector layer grid containing the control rod channel is equivalent to a square grid, and the grid side length and the channel area share are calculated; according to the control rod structure inside the channel, the probability expression of the equivalent reflector layer grid before and after the neutron beam penetrates the homogenization is obtained; based on the penetration probability conservation theory, a calculation formula for the neutron diffusion coefficient of the reflector layer considering the control rod structure is obtained.

[0007] As a preferred solution of the method for calculating the homogenized neutron diffusion coefficient of the control rod-containing reflector layer of the present invention, the grid side length and the hole area fraction are calculated as follows:

[0008]

[0009] Where A represents the cross-sectional area of ​​the reflector grid containing the control rod channel, R represents the equivalent radius of the channel, S represents the channel area, and ε represents the area share of the reflector grid in the channel.

[0010] As a preferred solution of the method for calculating the neutron diffusion coefficient of the homogenized reflector layer containing control rods of the present invention, the probability of the neutron beam penetrating the equivalent reflector grid before homogenization is expressed as:

[0011]

[0012] Among them, p inout,1 represents the probability of the neutron beam penetrating the equivalent reflection layer grid containing inner and outer control rods before homogenization, i represents the material number in the equivalent reflection layer grid, u represents the position variable perpendicular to the neutron beam direction in the equivalent reflection layer grid, Σ ref,tr represents the macroscopic transport cross section of the reflector material, Σ cr,out,tr represents the macroscopic transport cross section of the outer control rod material, Σ cr,in,tr represents the macroscopic transport cross section of the inner control rod material, l(u) represents the track length of the neutron beam entering the equivalent reflector grid from position u in the reflector material, and k out (u) The path length of the neutron beam from position u into the equivalent reflector grid and in the outer control rod material, k in (u) The path length of the neutron beam in the inner control rod material when it enters the equivalent reflector grid at position u.

[0013] As a preferred solution of the method for calculating the homogenized neutron diffusion coefficient of the control rod-containing reflector layer of the present invention, the track length in the reflector layer material, the track length in the outer control rod material, the track length in the inner control rod material and the side length of the equivalent reflector layer grid are expressed as follows:

[0014]

[0015]

[0016] Among them, R out,o represents the outer radius of the outer control rod, R out,i represents the inner radius of the outer control rod, R in,o represents the outer radius of the inner control rod, R in,i represents the inner radius of the inner control rod, and L represents the side length of the equivalent reflection layer grid.

[0017] As a preferred solution of the method for calculating the neutron diffusion coefficient of the homogenized reflector layer containing control rods described in the present invention, the probability of the neutron beam penetrating the equivalent reflector grid after homogenization is:

[0018]

[0019] Among them, p inout,2 represents the probability of the neutron beam penetrating the equivalent reflector grid containing inner and outer control rods after homogenization, represents the homogenized macroscopic transport cross section of the equivalent reflector grid with inner and outer control rods, represents the homogenized neutron diffusion coefficient of the equivalent reflector grid containing inner and outer control rods.

[0020] As a preferred solution of the method for calculating the homogenized neutron diffusion coefficient of the reflector layer containing control rods of the present invention, based on the penetration probability conservation theory, the probability of the neutron beam passing through the equivalent reflector grid before and after homogenization is equal, and the calculation of the neutron diffusion coefficient of the reflector layer considering the control rod structure is obtained, which specifically includes the calculation of the homogenized neutron diffusion coefficient of the reflector layer containing inner and outer control rods in the channel and the calculation of the homogenized neutron diffusion coefficient of the reflector layer containing only inner control rods or only outer control rods in the channel. The calculation formula of the homogenized neutron diffusion coefficient of the reflector layer containing inner and outer control rods in the channel is:

[0021]

[0022] As a preferred solution of the method for calculating the homogenized neutron diffusion coefficient of the reflective layer containing control rods of the present invention, the calculation of the homogenized neutron diffusion coefficient of the reflective layer containing only inner control rods or only outer control rods in the channel is expressed as:

[0023]

[0024] in, represents the homogenized neutron diffusion coefficient of the equivalent reflector grid containing the inner control rods, represents the homogenized neutron diffusion coefficient of the equivalent reflector grid including the outer control rods.

[0025] Another object of the present invention is to provide a control rod reflector homogenization neutron diffusion coefficient calculation system, which takes into account the convenience of user operation so that even non-professionals can easily complete the calculation task.

[0026] In order to solve the above technical problems, the present invention provides the following technical solutions: a control rod reflector homogenization neutron diffusion coefficient calculation system, comprising: a data input module, a grid division module, a homogenization processing module and a neutron diffusion coefficient calculation module; the data input module is used to input all basic data related to the calculation; the grid division module automatically performs grid division of the model according to the input geometric parameters and model characteristics; the homogenization processing module calculates the probability expression of the equivalent reflector grid before and after the neutron beam penetrates the homogenization according to the control rod structure inside the channel; the neutron diffusion coefficient calculation module calculates the neutron diffusion coefficient of the reflector considering the control rod structure based on the penetration probability conservation theory and using the data provided by the above modules.

[0027] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the method for calculating the neutron diffusion coefficient of a homogenized reflective layer containing a control rod are implemented.

[0028] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the method for calculating the neutron diffusion coefficient of a homogenized control rod reflector layer as described above.

[0029] Beneficial effects of the present invention: The method and system for calculating the homogenized neutron diffusion coefficient of a reflective layer containing control rods provided by the present invention adopt a component calculation program of reactor physics design, and convert the reflective layer grid containing control rod holes into a square grid, so as to obtain a probability expression of the equivalent reflective layer grid before and after the neutron beam penetrates and is homogenized. By using the penetration probability conservation theory, a calculation formula for the neutron diffusion coefficient of the reflective layer considering the control rod structure is obtained, which can effectively consider the absorption effect of the control rods inside the holes on neutrons, thereby improving the accuracy of subsequent core neutronic calculations. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0031] Figure 1 An overall flow chart of a method for calculating a homogenized neutron diffusion coefficient of a control rod reflector provided in one embodiment of the present invention;

[0032] Figure 2 A schematic diagram of an equivalent grid of a reflective layer including inner and outer control rods in a control rod channel including a method for calculating a homogenized neutron diffusion coefficient of a control rod reflective layer provided in accordance with an embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0034] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0035] Example 1

[0036] Reference Figure 1-Figure 2 , which is an embodiment of the present invention, provides a method for calculating the homogenized neutron diffusion coefficient of a control rod-containing reflector layer, comprising:

[0037] S1: Use the component calculation program to calculate the homogenized cross-section of the reflector layer and control rods of the pebble bed high temperature gas-cooled reactor;

[0038] Furthermore, the Monte Carlo particle transport calculation software NECP-MCX is used to calculate the homogenized cross sections of the reflector layer, inner control rods and outer control rods of the pebble bed high temperature gas cooled reactor.

[0039] S2: According to the model grid division, the reflection layer grid containing the control rod channel is equivalent to a square grid, and the grid side length and the channel area share are calculated;

[0040] Furthermore, according to the model grid division, the cross-sectional area of ​​the reflector grid containing the control rod channel and the internal channel area are determined, and the equivalent radius and area share of the channel when no control rod is inserted are calculated:

[0041]

[0042] Where:

[0043] A is the cross-sectional area of ​​the reflector grid containing the control rod holes;

[0044] R——Equivalent radius of the hole;

[0045] S——pore area;

[0046] ε is the area share of the hole in the reflector grid;

[0047] The reflector grid containing the control rod holes is equivalent to a square grid, such as Figure 2 As shown, the side length of the equivalent reflection layer grid is:

[0048]

[0049] Where:

[0050] L is the side length of the equivalent reflection layer grid.

[0051] S3: According to the control rod structure inside the hole, the probability expressions of the equivalent reflection layer grid before and after the neutron beam penetrates the homogenization are obtained respectively;

[0052] Furthermore, if the equivalent reflector grid contains both inner control rods and outer control rods, the probability of the neutron beam penetrating the equivalent reflector grid before homogenization is:

[0053]

[0054] Where:

[0055] p inout,1 ——the probability of the neutron beam penetrating the equivalent reflector grid containing inner and outer control rods before homogenization;

[0056] i——Material number in the equivalent reflection layer grid;

[0057] u is the position variable perpendicular to the neutron beam direction in the equivalent reflector grid;

[0058] Σ ref,tr ——Macroscopic transport cross section of the reflector material;

[0059] Σ cr,out,tr ——macroscopic transport cross section of the outer control rod material;

[0060] Σ cr,in,tr ——macroscopic transport cross section of inner control rod material;

[0061] l(u)——The track length of the neutron beam in the reflector material when it enters the equivalent reflector grid from position u;

[0062] k out (u) — the path length of the neutron beam in the outer control rod material from the position u into the equivalent reflector grid;

[0063] k in (u) — the path length of the neutron beam in the inner control rod material when it enters the equivalent reflector grid from position u;

[0064] It should be noted that Figure 2 It can be seen that l(u), k out (u), kin (u) are

[0065]

[0066] Where:

[0067] R out,o — the outer radius of the outer control rod;

[0068] R out,i —Inner radius of the outer control rod;

[0069] R in,o ——outer radius of the inner control rod;

[0070] R in,i —Inner radius of the inner control rod;

[0071] Furthermore, the probability of a neutron beam penetrating the equivalent reflection layer grid after homogenization is:

[0072]

[0073] Where:

[0074] p inout,2 ——the probability of the neutron beam penetrating the equivalent reflector grid containing inner and outer control rods after homogenization;

[0075] ——homogenized macroscopic transport cross section of the equivalent reflector grid including inner and outer control rods;

[0076] ——The homogenized neutron diffusion coefficient of the equivalent reflector grid including inner and outer control rods.

[0077] S4: Based on the theory of conservation of penetration probability, the calculation formula for the neutron diffusion coefficient of the reflector layer considering the control rod structure is obtained.

[0078] Furthermore, based on the theory of conservation of penetration probability, the probability of the neutron beam passing through the equivalent reflection layer grid before and after homogenization is equal. Combining equations (4) to (8) in step S3, the calculation formula for the homogenization neutron diffusion coefficient of the reflection layer containing inner and outer control rods in the channel is obtained:

[0079]

[0080] The homogenized neutron diffusion coefficient of the reflector layer containing inner and outer control rods in the channel is calculated based on the above formula.

[0081] It should be noted that, based on the above process steps, the calculation formula for the homogenized neutron diffusion coefficient of the reflector layer containing only inner control rods or only outer control rods in the channel can be obtained:

[0082]

[0083]

[0084] Where:

[0085] ——homogenized neutron diffusion coefficient of the equivalent reflector grid including the inner control rods;

[0086] ——The homogenized neutron diffusion coefficient of the equivalent reflector grid including the outer control rods.

[0087] Example 2

[0088] According to one embodiment of the present invention, a system for calculating neutron diffusion coefficient of a control rod reflector homogenization is provided, comprising:

[0089] Data input module, grid division module, homogenization processing module and neutron diffusion coefficient calculation module;

[0090] The data input module is used to input all basic data related to the calculation;

[0091] The meshing module automatically meshes the model according to the input geometric parameters and model characteristics;

[0092] The homogenization processing module calculates the probability expression of the neutron beam penetrating the equivalent reflection layer grid before and after homogenization according to the control rod structure inside the hole;

[0093] The neutron diffusion coefficient calculation module is based on the penetration probability conservation theory and uses the data provided by the above modules to calculate the neutron diffusion coefficient of the reflector layer taking into account the control rod structure.

[0094] Example 3

[0095] An embodiment of the present invention is different from the first two embodiments in that:

[0096] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program code.

[0097] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0098] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0099] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0100] Example 4

[0101] As an embodiment of the present invention, a method for calculating the neutron diffusion coefficient of a homogenized reflector layer containing control rods is provided. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0102] A modified model of the high temperature gas-cooled reactor nuclear power plant demonstration project HTR-PM was used for calculation verification. The difference between this model and the HTR-PM model is that the original 6 absorption ball channels are replaced by 6 control rod channels, that is, 30 control rod channels are evenly arranged in the model, and the control rods in all control rod channels are completely inserted into the bottom of the core.

[0103] The model was calculated using the self-developed high-temperature gas-cooled reactor core physics calculation program, with the NECP-MCX continuous energy calculation results as the reference solution and the existing technology as the comparison. The core keff calculation results are given in Table 1. Among them, when calculating using the existing technology, the control rod channel area is the gap area excluding the control rod material.

[0104] Table 1 Comparison of keff calculation results of HTR-PM modified model

[0105]

[0106] Compared with the prior art, the homogenized neutron diffusion coefficient of the control rod reflector layer is calculated based on the method of the present invention and then used in core neutronics calculations. The obtained keff is closer to the Monte Carlo reference solution.

[0107] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for calculating the homogenized neutron diffusion coefficient of a reflector layer containing control rods, characterized in that: include: Use component calculation program to calculate the homogenization cross section of the reflector layer and control rod of the pebble bed high temperature gas cooled reactor; According to the model grid division, the reflector grid containing the control rod channel is equivalent to a square grid, and the grid side length and channel area share are calculated; According to the control rod structure inside the hole, the probability expressions of the equivalent reflection layer grid before and after the neutron beam penetrates the homogenization are obtained respectively; Based on the theory of conservation of penetration probability, the calculation formula for the neutron diffusion coefficient of the reflector layer considering the control rod structure is obtained.

2. The method for calculating the homogenized neutron diffusion coefficient of the control rod-containing reflector layer according to claim 1, characterized in that: The grid side length and pore area fraction are calculated as follows: Where A represents the cross-sectional area of ​​the reflector grid containing the control rod channel, R represents the equivalent radius of the channel, S represents the channel area, and ε represents the area share of the reflector grid in the channel.

3. The method for calculating the homogenized neutron diffusion coefficient of the control rod-containing reflector layer according to claim 2, characterized in that: The probability of the neutron beam penetrating the equivalent reflection layer grid before homogenization is expressed as: Among them, p inout,1 represents the probability of the neutron beam penetrating the equivalent reflection layer grid containing inner and outer control rods before homogenization, i represents the material number in the equivalent reflection layer grid, u represents the position variable perpendicular to the neutron beam direction in the equivalent reflection layer grid, Σ ref,tr represents the macroscopic transport cross section of the reflector material, Σ cr,out,tr represents the macroscopic transport cross section of the outer control rod material, Σ cr,in,tr represents the macroscopic transport cross section of the inner control rod material, l(u) represents the track length of the neutron beam entering the equivalent reflector grid from position u in the reflector material, and k out (u) The path length of the neutron beam from position u into the equivalent reflector grid and in the outer control rod material, k in (u) The path length of the neutron beam in the inner control rod material when it enters the equivalent reflector grid at position u.

4. The method for calculating the homogenized neutron diffusion coefficient of the control rod-containing reflector layer according to claim 3, characterized in that: The track length in the reflector material, the track length in the outer control rod material, the track length in the inner control rod material and the side length of the equivalent reflector grid are expressed as follows: Among them, R out,o represents the outer radius of the outer control rod, R out,i represents the inner radius of the outer control rod, R in,o represents the outer radius of the inner control rod, R in,i represents the inner radius of the inner control rod, and L represents the side length of the equivalent reflection layer grid.

5. The method for calculating the homogenized neutron diffusion coefficient of the control rod-containing reflector layer according to claim 4, characterized in that: The probability of the neutron beam penetrating the homogenized equivalent reflection layer grid is: Among them, p inout,2 represents the probability of the neutron beam penetrating the equivalent reflector grid containing inner and outer control rods after homogenization, represents the homogenized macroscopic transport cross section of the equivalent reflector grid with inner and outer control rods, represents the homogenized neutron diffusion coefficient of the equivalent reflector grid containing inner and outer control rods.

6. The method for calculating the homogenized neutron diffusion coefficient of the control rod-containing reflector layer according to claim 4, characterized in that: Based on the penetration probability conservation theory, the probability of the neutron beam passing through the equivalent reflector grid before and after homogenization is equal, and the calculation of the reflector neutron diffusion coefficient considering the control rod structure is obtained, which specifically includes the calculation of the reflector homogenization neutron diffusion coefficient when the channel contains inner and outer control rods and the calculation of the reflector homogenization neutron diffusion coefficient when the channel contains only inner control rods or only outer control rods. The calculation formula of the reflector homogenization neutron diffusion coefficient when the channel contains inner and outer control rods is:

7. The method for calculating the homogenized neutron diffusion coefficient of the control rod-containing reflector layer according to claim 6, characterized in that: The calculation of the homogenized neutron diffusion coefficient of the reflector layer containing only inner control rods or only outer control rods in the channel is expressed as: in, represents the homogenized neutron diffusion coefficient of the equivalent reflector grid containing the inner control rods, represents the homogenized neutron diffusion coefficient of the equivalent reflector grid including the outer control rods.

8. A system using the method for calculating the homogenized neutron diffusion coefficient of the control rod reflector layer according to any one of claims 1 to 7, characterized in that: include: Data input module, grid division module, homogenization processing module and neutron diffusion coefficient calculation module; The data input module is used to input all basic data related to the calculation; The meshing module automatically performs meshing of the model according to the input geometric parameters and model characteristics; The homogenization processing module calculates the probability expression of the neutron beam penetrating the equivalent reflection layer grid before and after homogenization according to the control rod structure inside the channel; The neutron diffusion coefficient calculation module is based on the penetration probability conservation theory and uses the data provided by the above modules to calculate the neutron diffusion coefficient of the reflector layer taking into account the control rod structure.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method for calculating the homogenized neutron diffusion coefficient of the control rod-containing reflector layer according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for calculating the homogenized neutron diffusion coefficient of the control rod-containing reflector layer according to any one of claims 1 to 7 are implemented.

Images