Analysis method, analyzer, and program

Abstract

To provide a method for calculating an effective cross sectional area by taking into account the adjacency effect of graphite.SOLUTION: An analysis method includes: calculating a relation between an effective cross sectional area and a Dancoff factor on the basis of an effective cross sectional area and a Dancoff factor having been calculated regarding a fuel assembly and an effective cross sectional area and a Dancoff factor for the case where the periphery of the fuel assembly is surrounded by graphite; calculating the Dancoff factor of each of a plurality of fuels included in each fuel assembly in a reactor core by taking into account the adjacency effect of graphite; and calculating the cross sectional area of each of fuels on the basis of the calculated Dancoff factor and the relation between the effective cross sectional area and the Dancoff factor.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an analysis method, an analysis apparatus, and a program.

Background Art

[0002] Patent Document 1 discloses a method for calculating the effective cross-sectional area in the resonance region of a fuel assembly corresponding to a wide range of calculation conditions from a state where the inside of a light water reactor core is filled with a moderator (cooling water) to a state where it is lost without deteriorating the calculation accuracy. In a high-temperature gas reactor, graphite is used as the moderator instead of cooling water. When calculating the effective cross-sectional area of the core in a high-temperature gas reactor, it is necessary to consider the influence of graphite.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] To provide a technique for calculating the effective cross-sectional area by taking into account the effect of adjacent graphite.

[0005] The present disclosure provides an analysis method, an analysis apparatus, and a program capable of solving the above problems.

Means for Solving the Problems

[0006] The analysis method of the present disclosure includes: a step of calculating the relationship between the effective cross-section area and the Doppler coefficient based on a first effective cross-section area and a first Doppler coefficient obtained by performing resonance calculation for a single fuel body in a core using graphite as a moderator, in which one or more fuel bodies are arranged, and a second effective cross-section area and a second Doppler coefficient obtained by performing the resonance calculation assuming that the periphery of the fuel body is surrounded by graphite; a step of calculating the Doppler coefficient of each of a plurality of fuels included in the fuel body for all the fuel bodies in the core, taking into account the adjacent effect of the graphite; and a step of calculating the effective cross-section area of each of the fuels based on the calculated Doppler coefficient of the fuel and the relationship between the effective cross-section area and the Doppler coefficient.

[0007] The analysis apparatus of the present disclosure includes: means for calculating the relationship between the effective cross-section area and the Doppler coefficient based on a first effective cross-section area and a first Doppler coefficient obtained by performing resonance calculation for a single fuel body in a core using graphite as a moderator, in which one or more fuel bodies are arranged, and a second effective cross-section area and a second Doppler coefficient obtained by performing the resonance calculation assuming that the periphery of the fuel body is surrounded by graphite; means for calculating the Doppler coefficient of each of a plurality of fuels included in the fuel body for all the fuel bodies in the core, taking into account the adjacent effect of the graphite; and means for calculating the effective cross-section area of each of the fuels based on the calculated Doppler coefficient of the fuel and the relationship between the effective cross-section area and the Doppler coefficient.

[0008] Further, the program of the present disclosure causes a computer to calculate the relationship between the effective cross-sectional area and the Doppler coefficient based on a first effective cross-sectional area and a first Doppler coefficient obtained by performing resonance calculation on a single fuel body in a core using graphite as a moderator, in which one or more fuel bodies are arranged, and a second effective cross-sectional area and a second Doppler coefficient obtained by performing the resonance calculation assuming that the periphery of the fuel body is surrounded by graphite; calculate the Doppler coefficient of each of the plurality of fuels included in the fuel body for all the fuel bodies in the core, taking into account the adjacent effect of the graphite; and calculate the effective cross-sectional area of each of the fuels based on the calculated Doppler coefficient of the fuel and the relationship between the effective cross-sectional area and the Doppler coefficient.

Advantages of the Invention

[0009] According to the analysis method, analysis device, and program of the present disclosure, the effective cross-sectional area can be calculated taking into account the effect of adjacent graphite.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0011] <Embodiment> Hereinafter, the analysis device of the present disclosure will be described with reference to FIGS. 1 to 6. (Configuration) FIG. 1 is a block diagram showing an example of an analysis device according to an embodiment. The analysis device 10 calculates the effective cross-sectional area in the entire core system such as a high-temperature gas furnace using graphite as a moderator by performing resonance calculations for a single fuel assembly without performing resonance calculations for a multi-fuel assembly. The analysis device 10 includes an input reception unit 11, a calculation unit 12, an output unit 13, and a storage unit 14.

[0012] The input reception unit 11 receives information and instructions input using an input device such as a keyboard, mouse, touch panel, buttons, etc. For example, the input reception unit 11 receives the input of information necessary for calculating the effective cross-sectional area, such as the arrangement pattern information of fuel in the core. The input reception unit 11 records the received information in the storage unit 14 or outputs it to the calculation unit 12.

[0013] The calculation unit 12 calculates the effective cross-sectional area of the core of the high-temperature gas reactor. An outline of the core of the high-temperature gas reactor is shown in FIG. 2. The core 1 includes a hexagonal control rod block 2 including a plurality of holes 2b for inserting control rods and control rods 2a inserted into the holes 2b, a fuel body 3 which is a hexagonal block including a large number of fuel compacts 3a, and a hexagonal graphite block 4 filled with graphite. The core 1 illustrated in FIG. 2 is an example of a part of the core, and in the entire core, more control rod blocks 2, fuel bodies 3, and graphite blocks 4 are arranged. Also, in the example of FIG. 2, five fuel bodies 3 and one graphite block 4 are arranged around the control rod block 2, but the arrangement pattern of each block is not limited to this. For example, six fuel bodies 3 may be arranged so as to surround the control rod block 2, or graphite blocks 4 may be arranged in two or more of the six regions. Graphite is filled in the regions other than the fuel compacts 3a of the fuel body 3 and the regions outside the holes 2b of the control rod block 2. The effective cross-sectional area in the state where fuel is loaded in the core 1 differs depending on whether the block adjacent to the fuel body 3 is a control rod block 2, a fuel body 3, or a graphite block 4. Therefore, in order to calculate the effective cross-sectional area of the fuel material that causes resonance in the state where fuel is loaded, it is necessary to perform resonance calculation in the entire core system. However, this method has a high calculation load. Therefore, in the present embodiment, by utilizing the property that there is a linear relationship between the Dancoff coefficient and the effective cross-sectional area, only the transport calculation for obtaining the Dancoff coefficient is performed for the entire core system, and the resonance calculation is executed for a single fuel body. Then, using those results, the effective cross-sectional area in the entire core system is calculated. Thereby, the effective cross-sectional area of the entire core system is calculated without performing resonance calculation for a multi-fuel body. The details are shown below.

[0014] The calculation unit 12 performs resonance calculations incorporating the adjacent effect of graphite for fuel substances such as uranium present in the fuel compacts 3a in the reactor core 1, and calculates the effective cross section for a single fuel body 3. For substances other than fuel substances, the effective cross section is calculated by the conventional effective cross section calculation for a single fuel body 3. The resonance calculation incorporating the adjacent effect of graphite will be described with reference to FIGS. 3 and 4. As illustrated in FIG. 3, the calculation unit 12 performs (a) resonance calculation for a single fuel body 3 and (b) resonance calculation for a single fuel body 3 considering the influence of the adjacent graphite reflector.

[0015] (a) In the resonance calculation for a single fuel body 3, it is assumed that only the fuel body 3 is arranged in the reactor core 1 and the surroundings are surrounded by the fuel body 3, and resonance calculation is performed for the single fuel body 3 to be calculated. A set of effective cross section and Doppler coefficient is obtained by the resonance calculation.

[0016] (b) In the resonance calculation for a single fuel body 3 incorporating the influence of the adjacent graphite reflector, resonance calculation is performed assuming that only the graphite block 4 surrounds the outside of the fuel body 3 to be calculated. To simulate this state, for example, a value several times (it may be 5 to 10 times) the normal value (when not assuming being surrounded by the graphite block 4) is set for the number density of graphite in the outer peripheral portion 3b of the fuel body 3 to be calculated, and resonance calculation is performed. The moderator of the high-temperature gas reactor is graphite, and when the fuel body 3 is loaded in the reactor core, there is a possibility that the graphite block 4 or the control rod block 2 is arranged adjacent to it. In such an arrangement, the effective cross section in the resonance region is strongly affected by the graphite reflector. As one method of calculating the effective cross section incorporating the influence of the graphite reflector, the situation where graphite is arranged in the outer peripheral portion 3b is assumed, and resonance calculation is performed. By the resonance calculation, a set of effective cross section incorporating the influence of the graphite reflector and the Doppler coefficient is obtained.

[0017] There is a strong linear relationship between the effective cross-sectional area and the Dancoff coefficient. Therefore, from the set of the effective cross-sectional area and the Dancoff coefficient obtained from the resonance calculation in (a) and the set of the effective cross-sectional area and the Dancoff coefficient incorporating the influence of the graphite reflector obtained from the resonance calculation in (b), a relationship as illustrated in FIG. 4 can be calculated. The vertical axis of FIG. 4 is the effective cross-sectional area, and the horizontal axis is the Dancoff coefficient. The Dancoff coefficient takes values from 0 to 1, and the closer it is to 1, the more it indicates a state where there is no fuel around. Therefore, the Dancoff coefficient obtained from the resonance calculation of the single fuel body 3 incorporating the influence of the adjacent graphite reflector in (b) takes a value closer to 1 than the Dancoff coefficient obtained from the total calculation in (a). Point 4a in FIG. 4 corresponds to the set of the Dancoff coefficient and the effective cross-sectional area obtained from the total calculation in (a), and point 4b corresponds to the set of the Dancoff coefficient and the effective cross-sectional area obtained from the total calculation in (b). The line 4c connecting point 4a and point 4b shows the relationship between the effective cross-sectional area and the Dancoff coefficient. The calculation unit 12 calculates a function or a table (for example, line 4c) showing the relationship between the effective cross-sectional area and the Dancoff coefficient from the two resonance calculations of (a) and (b) for the single fuel body.

[0018] Subsequently, the calculation unit 12 performs a monochromatic transport calculation in a two-dimensional full-core system to calculate the Dancoff coefficient for each of all the fuel compacts 3a included in the core 1. This calculation is executed to calculate the Dancoff coefficient. In the monochromatic transport calculation, since the transport calculation is executed considering only one group for the neutron energy, the calculation load is light, and the Dancoff coefficient of each fuel compact 3a can be calculated in a short time. Further, by performing the transport calculation in a two-dimensional full-core system, the Dancoff coefficient corresponding to the arrangement pattern of each block in the core 1, that is, the Dancoff coefficient of each fuel compact 3a incorporating the adjacent effect of graphite by the graphite block 4 and the control rod block 2 adjacent to the fuel assembly 3 in the actual loading pattern is calculated. When the Dancoff coefficient of each fuel compact 3a is calculated, the calculation unit 12 calculates the effective cross-sectional area of each fuel compact 3a from a table (for example, line 4c) showing the relationship between the Dancoff coefficient, the effective cross-sectional area, and the Dancoff coefficient of each fuel compact 3a. For example, if the value of the Dancoff coefficient calculated for a certain fuel compact 3a is c1 in FIG. 4, the effective cross-sectional area of the fuel compact 3a can be calculated as e1 from line 4c. Also, if the Dancoff coefficient of another fuel compact 3a is c2, the effective cross-sectional area of the fuel compact 3a can be calculated as e2. In this way, by interpolating or extrapolating the Dancoff coefficient calculated in the full-core system with line 4c, the calculation unit 12 calculates the effective cross-sectional area for all the fuel compacts 3a.

[0019] The adjacent effect of graphite is reflected only in the effective cross-sectional area of the fuel compact 3a. Since no resonance substances are included other than the fuel compact 3a, the conventional calculation result of the effective cross-sectional area for the single fuel assembly 3 is used.

[0020] The output unit 13 outputs the effective cross-sectional area calculated by the calculation unit 12 to other devices, electronic files, etc. The memory unit 14 stores arrangement pattern information of fuel and the like, such as how the control rod blocks 2, fuel bodies 3, and graphite blocks 4 are arranged in the reactor core 1, and how various fuels are arranged in the fuel bodies 3, various setting information, processing data during calculations, and the like. Further, the memory unit 14 stores a calculation code that is a computer program for calculating the effective cross-sectional area and a calculation code that is a computer program for performing neutron transport calculations. The calculation unit 12 performs the resonance calculations of (a) and (b) above and the calculation of the effective cross-sectional area other than the fuel compact 3a using the calculation code for calculating the effective cross-sectional area. The calculation unit 12 calculates the Dankoff coefficient for each fuel compact 3a of the entire reactor core system using the calculation code for performing neutron transport calculations.

[0021] (Operation) Next, the operation of the analysis device 10 will be described with reference to FIG. 5. FIG. 5 is a flowchart showing an example of the calculation process of the effective cross-sectional area according to the embodiment. As a premise, arrangement pattern information of fuel and the like is registered in the memory unit 14. First, the user instructs the analysis device 10 to calculate the effective cross-sectional area. The input reception unit 11 receives this instruction, and the calculation unit 12 starts the calculation of the effective cross-sectional area. First, the calculation unit 12 calculates the effective cross-sectional area for a predetermined single fuel body 3 (step S1). The calculation unit 12 performs a resonance calculation assuming a reactor core 1 in which only the fuel body 3 is arranged on one side, and calculates a set of the Dankoff coefficient and the effective cross-sectional area of the single fuel body 3. In step S1, the effective cross-sectional area is also calculated for substances without resonance contained in the single fuel body 3.

[0022] Next, the calculation unit 12 calculates the effective cross-sectional area of the single fuel body 3 taking into account the adjacent effect of the graphite reflector (step S2). The calculation unit 12 sets a sufficiently large number density of graphite on the outer peripheral portion 3b of the same fuel body 3 as in step S1, for example, in order to incorporate the adjacent effect of the graphite reflector into the resonance calculation, and performs the resonance calculation. Thereby, a set of the Dankoff coefficient and the effective cross-sectional area of a single fuel body 3 surrounded by six graphite blocks 4 is calculated. Note that the actual order of steps S1 and S2 may be reversed.

[0023] Next, the calculation unit 12 creates a table showing the relationship between the effective cross-sectional area and the Dancoff coefficient (step S3). For example, the calculation unit 12 plots the set of Dancoff coefficients and effective cross-sectional areas calculated in step S1 and the set of Dancoff coefficients and effective cross-sectional areas calculated in step S2 in a two-dimensional coordinate system with the Dancoff coefficient and the effective cross-sectional area as the coordinate axes, as illustrated in FIG. 4, and draws a straight line connecting these two points. This straight line is the table showing the relationship between the effective cross-sectional area and the Dancoff coefficient.

[0024] Next, the calculation unit 12 performs a transport calculation for the entire core system and calculates the Dancoff coefficients of all the fuel compacts 3a considering the graphite reflector (step S4). The calculation unit 12 performs a single-color transport calculation based on the arrangement pattern information of the core 1, thereby taking into account the influence of the control rod blocks 2, graphite blocks 4, and graphite in the fuel bodies 3 arranged in the core 1, and calculates the Dancoff coefficients of all the fuel compacts 3a arranged in the core 1.

[0025] Next, the calculation unit 12 calculates the effective cross-sectional areas of all the fuel compacts (step S5). The calculation unit 12 linearly interpolates and extrapolates each of the Dancoff coefficients calculated in step S4 using the table showing the relationship between the effective cross-sectional area and the Dancoff coefficient created in step S3 to calculate the effective cross-sectional area of each fuel compact 3a. The calculation unit 12 writes and stores the effective cross-sectional area of each fuel compact 3a in the storage unit 14 (step S6). Also, for the effective cross-sectional area of substances other than the fuel substance (substances without resonance) in the core 1, the calculation unit 12 writes and stores the effective cross-sectional area calculated by the calculation of the effective cross-sectional area for the single fuel body in step S1 in the storage unit 14. The recorded effective cross-sectional areas in the entire core system can be used for core calculations (such as neutron transport calculations) of the core 1.

[0026] (Effect) As described above, according to the present embodiment, it is not necessary to simulate the influence of adjacent blocks for each arrangement pattern of various blocks (control rod block 2, fuel body 3, graphite block 4) loaded in the core 1. In a single fuel body calculation, by simply adding a calculation with changed conditions once (the resonance calculation in (b) above), a resonance calculation considering the adjacent graphite reflector becomes possible. According to the present embodiment, a graphite number density is set in the outer peripheral portion 3b of a single fuel body 3 such that the Dancoff coefficient approaches 1. Thereby, it becomes possible to calculate an effective cross-sectional area incorporating the effect of the adjacent graphite reflector. According to the present embodiment, without multi-fuel body calculation, it is possible to calculate an effective cross-sectional area incorporating the influence of the adjacent graphite reflector while maintaining a single fuel body calculation. Thereby, the effective cross-sectional area of the core using graphite as a moderator can be calculated in a short time (at high speed) with a small calculation load.

[0027] FIG. 6 is a diagram showing an example of the hardware configuration of the analysis device. The computer 900 includes a CPU 901, a main storage device 902, an auxiliary storage device 903, an input / output interface 904, and a communication interface 905. The above-described analysis device 10 is implemented in the computer 900. And each function described above is stored in the auxiliary storage device 903 in the form of a program. The CPU 901 reads the program from the auxiliary storage device 903 and expands it in the main storage device 902, and executes the above processing according to the program. Further, the CPU 901 secures a storage area in the main storage device 902 according to the program. Further, the CPU 901 secures a storage area in the auxiliary storage device 903 for storing data during processing according to the program.

[0028] Note that a program for realizing all or part of the functions of the analysis device 10 may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed to perform the processing by each functional unit. Here, the "computer system" shall include hardware such as an OS and peripheral devices. Further, the "computer system" shall include a homepage providing environment (or display environment) if the WWW system is used. Further, the "computer-readable recording medium" refers to a portable medium such as a CD, DVD, USB, etc., and a storage device such as a hard disk built into a computer system. Further, when this program is distributed to the computer 900 via a communication line, the computer 900 that has received the distribution may expand the program in the main storage device 902 and execute the above processing. Further, the above program may be for realizing a part of the above-described functions, and may further be capable of being realized in combination with a program already recorded in the computer system for the above-described functions.

[0029] As described above, some embodiments according to the present disclosure have been described, but all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

[0030] <Supplementary Note> The analysis method, analysis device, and program described in the embodiments can be understood as follows, for example.

[0031] (1) The analysis method according to the first aspect includes a step of calculating the relationship between the effective cross-sectional area and the Dannehoff coefficient based on the first effective cross-sectional area and the first Dannehoff coefficient obtained by performing resonance calculation on a single fuel body in a core using graphite as a moderator in which one or more fuel bodies are arranged, and the second effective cross-sectional area and the second Dannehoff coefficient obtained by performing the resonance calculation assuming that the periphery of the fuel body is surrounded by graphite; a step of calculating the Dannehoff coefficient of each of the plurality of fuels included in the fuel body while taking into account the adjacent effect of the graphite for all the fuel bodies in the core; and a step of calculating the effective cross-sectional area of each of the fuels based on the calculated Dannehoff coefficient of the fuel and the relationship between the effective cross-sectional area and the Dannehoff coefficient. Thus, without performing a multi-fuel body calculation, it is possible to calculate the effective cross-sectional area of the entire core system considering the adjacent effect of graphite only by calculating a single fuel body.

[0032] (2) The analysis method according to the second aspect is the analysis method of (1), and in order to perform the resonance calculation assuming that the periphery of the fuel body is surrounded by graphite, a value that is a predetermined multiple of the number density of the graphite at the outer peripheral portion of the fuel body is set as compared with the case where it is not assumed to be surrounded by graphite. Thus, the adjacent effect of graphite can be taken into account.

[0033] (3) The analysis method according to the third aspect is the analysis method of (1) to (2), and in the step of calculating the relationship, based on the fact that the effective cross-sectional area and the Dannehoff coefficient have a linear relationship, a function or a table showing the relationship between the effective cross-sectional area and the Dannehoff coefficient is calculated from the first effective cross-sectional area and the first Dannehoff coefficient, and the second effective cross-sectional area and the second Dannehoff coefficient. Thus, the relationship between the effective cross-sectional area and the Dannehoff coefficient can be calculated.

[0034] (4) The analysis method according to the fourth aspect is the analysis methods of (1) to (3), and in the step of calculating the Dancoff coefficient considering the influence of the graphite, the Dancoff coefficient is calculated by performing a monochromatic transport calculation for the entire core system. Thereby, the Dancoff coefficients of all fuel compacts can be calculated at low load and in a short time.

[0035] (5) The core analysis method according to the fifth aspect is the core analysis methods of (1) to (4), and in the core, the fuel body, the graphite block, and the block containing graphite and control rods are arranged. Thereby, it can also be applied to a high-temperature gas reactor.

[0036] (6) The analysis device according to the sixth aspect includes means for calculating the relationship between the effective cross-sectional area and the Dancoff coefficient based on the first effective cross-sectional area and the first Dancoff coefficient obtained by performing resonance calculation for a single fuel body in a core using graphite as a moderator in which one or more fuel bodies are arranged, and the second effective cross-sectional area and the second Dancoff coefficient obtained by performing the resonance calculation assuming that the periphery of the fuel body is surrounded by graphite; means for calculating the Dancoff coefficient of each of a plurality of fuels contained in the fuel body by taking into account the adjacent effect of the graphite for all the fuel bodies in the core; and means for calculating the effective cross-sectional area of each of the fuels based on the calculated Dancoff coefficient of the fuel and the relationship between the effective cross-sectional area and the Dancoff coefficient.

[0037] (7) The program according to the seventh aspect causes a computer to perform a step of calculating the relationship between the effective cross-sectional area and the Doppler coefficient based on a first effective cross-sectional area and a first Doppler coefficient obtained by performing resonance calculation on a single fuel body in a reactor core having graphite as a moderator in which one or more fuel bodies are arranged, and a second effective cross-sectional area and a second Doppler coefficient obtained by performing the resonance calculation assuming that the periphery of the fuel body is surrounded by graphite; a step of calculating the Doppler coefficient of each of a plurality of fuels included in the fuel body for all the fuel bodies in the reactor core while taking into account the adjacent effect of the graphite; and a step of calculating the effective cross-sectional area of each of the fuels based on the calculated Doppler coefficient of the fuel and the relationship between the effective cross-sectional area and the Doppler coefficient.

Explanation of Signs

[0038] 1 ··· Reactor core 2 ··· Control rod block 2a ··· Control rod 2b ··· Hole 3 ··· Fuel body 3a ··· Fuel compact 4 ··· Graphite block 10 ··· Analysis device 11 ··· Input reception unit 12 ··· Calculation unit 13 ··· Output unit 14 ··· Storage unit 900 ··· Computer 901 ··· CPU 902 ··· Main memory device 903 ··· Auxiliary storage device 904 ··· Input / output interface 905 ··· Communication interface

Claims

1. A step of calculating the relationship between the effective cross-section area and the Doppler coefficient based on the first effective cross-section area and the first Doppler coefficient obtained by performing resonance calculation for a single one of the fuel bodies in a core using graphite as a moderator in which one or more fuel bodies are arranged, and the second effective cross-section area and the second Doppler coefficient obtained by performing the resonance calculation assuming that the periphery of the fuel body is surrounded by graphite; A step of calculating the Doppler coefficient for each of the plurality of fuels contained in the fuel body while taking into account the adjacent effect of the graphite for all the fuel bodies in the core; A step of calculating the effective cross-section area for each of the fuels based on the calculated Doppler coefficient of the fuel and the relationship between the effective cross-section area and the Doppler coefficient; An analysis method comprising the steps.

2. In order to perform the resonance calculation assuming that the periphery of the fuel body is surrounded by graphite, a value that is a predetermined multiple of the number density of the graphite at the outer peripheral portion of the fuel body is set as compared with the case where it is not assumed to be surrounded by graphite. The analysis method according to Claim 1.

3. In the step of calculating the relationship, based on the fact that the effective cross-section area and the Doppler coefficient have a linear relationship, a function or a table showing the relationship between the effective cross-section area and the Doppler coefficient is calculated from the first effective cross-section area and the first Doppler coefficient, and the second effective cross-section area and the second Doppler coefficient. The analysis method according to Claim 1 or Claim 2.

4. In the step of calculating the Doppler coefficient while taking into account the adjacent effect of the graphite, the Doppler coefficient is calculated by performing a monochromatic transport calculation for the entire core system. The analysis method according to Claim 1 or Claim 2.

5. In the core, the fuel body, a graphite block, and a block containing graphite and a control rod are arranged. The analysis method according to Claim 1 or Claim 2.

6. Means for calculating the relationship between the effective cross-section area and the Doppler coefficient based on the first effective cross-section area and the first Doppler coefficient obtained by performing resonance calculation for a single one of the fuel bodies in a core using graphite as a moderator in which one or more fuel bodies are arranged, and the second effective cross-section area and the second Doppler coefficient obtained by performing the resonance calculation assuming that the periphery of the fuel body is surrounded by graphite; means for calculating the Dankoff coefficient of each of the plurality of fuels contained in the fuel body for all of the fuel bodies in the core, taking into account the adjacent effect of the graphite; means for calculating the effective cross-sectional area of each of the fuels based on the calculated Dankoff coefficient of the fuel and the relationship between the effective cross-sectional area and the Dankoff coefficient; An analysis device comprising the above.

7. On a computer, a first effective cross-sectional area and a first Dankoff coefficient obtained by performing resonance calculation for a single fuel body in a core using graphite as a moderator in which one or more fuel bodies are arranged, and a second effective cross-sectional area and a second Dankoff coefficient obtained by performing the resonance calculation assuming that the periphery of the fuel body is surrounded by graphite, and calculating the relationship between the effective cross-sectional area and the Dankoff coefficient based on these; for all of the fuel bodies in the core, calculating the Dankoff coefficient of each of the plurality of fuels contained in the fuel body, taking into account the adjacent effect of the graphite; calculating the effective cross-sectional area of each of the fuels based on the calculated Dankoff coefficient of the fuel and the relationship between the effective cross-sectional area and the Dankoff coefficient; A program for causing the above to be executed.

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