A method and device for checking symmetry of power distribution of hexagonal core

Abstract

The present application belongs to the field of nuclear power plant reactor operation and safety technology, and specifically relates to a method and device for checking the symmetry of power distribution of a hexagonal core; the method comprises: obtaining the power peak factor of the fuel assemblies in each symmetric group of the hexagonal core after the reactor power meets a preset power threshold and reaches a xenon equilibrium state; the hexagonal core is pre-divided into a plurality of sectors; the fuel assemblies in the symmetric group are respectively selected from the symmetric positions of each of the sectors; the absolute value of the difference between the power peak factor of each fuel assembly in each of the symmetric groups and the average power peak factor of the fuel assemblies in the symmetric group is determined to obtain the relative power deviation of each fuel assembly in the hexagonal core; judging whether the hexagonal core has good symmetry according to the relative power deviation and the average power peak factor, which can assist in judging the safety state of the reactor and provide technical guarantee for the safe and stable operation of the nuclear power unit.

Description

Technical Field

[0001] The present application belongs to the field of nuclear power plant reactor operation and safety technology, and specifically relates to a method and device for checking the symmetry of power distribution in a hexagonal core. Background Art

[0002] The reactors of pressurized water reactor nuclear power units generally adopt a symmetrical loading method, and the core power distribution generally shows good symmetry, which is a key condition to ensure the stable operation and control of the reactor. The core loading error, the loss of sealing of nuclear fuel elements, improper operation and control of the reactor may break the good symmetry of the core power distribution. Therefore, regular inspection of the symmetry of the reactor core power distribution is a work item that nuclear power unit operators must implement.

[0003] However, due to the particularity of its loading method, the hexagonal core exhibits core power distribution characteristics different from other types of reactors, and its symmetry inspection method is also different from other types of reactors. The existing reactor core power distribution symmetry inspection method is not applicable. Summary of the invention

[0004] The purpose of the present application is to provide a method and device for checking the symmetry of the power distribution of a hexagonal core, so as to solve the problem that the existing method for checking the symmetry of the power distribution of the reactor core is not applicable because the hexagonal core exhibits core power distribution characteristics different from those of other types of reactors due to the particularity of its loading method.

[0005] Technical solution to achieve the purpose of this application:

[0006] The first aspect of the present application provides a method for checking the symmetry of power distribution in a hexagonal core, the method comprising:

[0007] After the reactor power meets a preset power threshold and reaches a xenon equilibrium state, the power peak factor of the fuel assemblies in each symmetric group of the hexagonal core is obtained; the hexagonal core is pre-divided into a plurality of sectors; the fuel assemblies in the symmetric group are respectively selected from the symmetric positions of each of the sectors;

[0008] Determine the absolute value of the difference between the power peak factor of each fuel assembly in each of the symmetrical groups and the average value of the power peak factor of the fuel assemblies in the symmetrical group, and obtain the relative power deviation of each fuel assembly in the hexagonal core;

[0009] Whether the hexagonal core has good symmetry is determined according to the relative power deviation and the average power peak factor.

[0010] Optionally, the fuel assemblies in the symmetric group are selected from symmetrical positions of each of the sectors, and fuel assemblies of the same type are integrated into the same symmetric group.

[0011] Optionally, the step of obtaining the power peak factor of the fuel assemblies in each symmetric group of the hexagonal core further includes:

[0012] Determining whether the power peak factor of each fuel assembly is less than a power peak factor boundary value corresponding to the reactor power;

[0013] If yes, then determining the absolute value of the difference between the power peak factor of each fuel assembly in each of the symmetric groups and the average value of the power peak factor of the symmetric group is performed;

[0014] If not, the power peak factor monitoring of the corresponding fuel assembly is considered unreliable.

[0015] Optionally, the determining whether the power peak factor of each fuel assembly is less than a power peak factor boundary value corresponding to the reactor power specifically includes:

[0016] When the reactor power is 100% of the rated power, it is determined whether the power peak factor of each fuel assembly is less than 1.35.

[0017] Optionally, judging whether the hexagonal core has good symmetry according to the relative power deviation and the average value of the power peak factor specifically includes:

[0018] Determining a relative power deviation threshold of each of the symmetrical groups according to an average power peak factor of the symmetrical group fuel assemblies;

[0019] It is determined whether the relative power deviation of each fuel assembly is not greater than the relative power deviation threshold of the corresponding symmetric group.

[0020] Optionally, when the average power peak factor of the symmetrical group fuel assemblies is greater than 1.1, the relative power deviation threshold of the symmetrical group is 0.1; when the average power peak factor of the symmetrical group fuel assemblies is not greater than 1.1, the relative power deviation threshold of the symmetrical group is 0.25.

[0021] A second aspect of the present application provides a device for checking symmetry of power distribution of a hexagonal core, the device comprising: an obtaining module, a determining module and a first judging module;

[0022] The acquisition module is used to obtain the power peak factor of the fuel assemblies in each symmetric group of the hexagonal core after the reactor power meets the preset power threshold and reaches the xenon equilibrium state; the hexagonal core is pre-divided into a plurality of sectors; the fuel assemblies in the symmetric group are respectively selected from the symmetric positions of each of the sectors;

[0023] The determination module is used to determine the absolute value of the difference between the power peak factor of each fuel assembly in each of the symmetrical groups and the average power peak factor of the fuel assemblies in the symmetrical group, so as to obtain the relative power deviation of each fuel assembly in the hexagonal core;

[0024] The first judgment module is used to judge whether the hexagonal core has good symmetry according to the relative power deviation and the power peak factor average value.

[0025] Optionally, the device further includes: a second judgment module;

[0026] The second judgment module is used to judge whether the power peak factor of each fuel assembly is less than the power peak factor boundary value corresponding to the reactor power;

[0027] The determination module is specifically configured to, when the judgment result of the second judgment module is yes, execute the determination of the absolute value of the difference between the power peak factor of each fuel assembly in each of the symmetric groups and the average value of the power peak factor of the symmetric group.

[0028] Optionally, the first determination module is specifically configured to:

[0029] Determining a relative power deviation threshold of each of the symmetrical groups according to an average power peak factor of the symmetrical group fuel assemblies;

[0030] It is determined whether the relative power deviation of each fuel assembly is not greater than the relative power deviation threshold of the corresponding symmetric group.

[0031] Optionally, when the average power peak factor of the symmetrical group fuel assemblies is greater than 1.1, the relative power deviation threshold of the symmetrical group is 0.1; when the average power peak factor of the symmetrical group fuel assemblies is not greater than 1.1, the relative power deviation threshold of the symmetrical group is 0.25.

[0032] The beneficial technical effects of this application are:

[0033] The embodiment of the present application provides a method and device for checking the symmetry of the power distribution of a hexagonal core of a nuclear power plant. In view of the particularity of the hexagonal core loading method, the fuel assembly loading area in the core is divided into a number of symmetry groups in different symmetry methods to check the relative deviation of the power peak factor of the fuel assembly, and the boundary value and relative deviation evaluation standard of the power peak factor of the fuel assembly are given. This provides a method for checking the symmetry of the power distribution of the hexagonal core of a nuclear power plant during the power operation stage, can assist in judging the safety status of the reactor, and provide technical guarantee for the safe and stable operation of the nuclear power unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1A schematic diagram of a process for checking the symmetry of power distribution in a hexagonal core of a nuclear power plant provided in an embodiment of the present application;

[0035] Figure 2 This is a schematic diagram of the loading arrangement of nuclear fuel assemblies of a hexagonal core of a nuclear power plant in an embodiment of the present application;

[0036] Figure 3 This is a layout diagram of neutron flux detectors and adjustment rods of a hexagonal core of a nuclear power plant in an embodiment of the present application;

[0037] Figure 4 is the Kq boundary value when a hexagonal core of a nuclear power plant in an embodiment of the present application operates at different reactor powers;

[0038] Figure 5 A schematic structural diagram of a device for checking the symmetry of power distribution in a hexagonal core of a nuclear power plant provided in an embodiment of the present application. DETAILED DESCRIPTION

[0039] In order to make those skilled in the art better understand the present application, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the embodiments described below are only a part of the embodiments of the present application, not all. Based on the embodiments recorded in the present application, all other embodiments obtained by those skilled in the art without paying creative work are within the scope of protection of the present application.

[0040] In order to solve the problems of the prior art, an embodiment of the present application provides a method and device for checking the symmetry of the power distribution of a hexagonal core of a nuclear power plant. By checking the monitoring reliability and relative deviation of the power peak factor of the fuel assembly in the core measurement system, it is determined that the core power distribution has good symmetry, thereby improving the safety and reliability of the operation of the nuclear power unit.

[0041] Based on the above content, in order to clearly and in detail illustrate the above advantages of the present application, the specific implementation methods of the present application will be described below in conjunction with the accompanying drawings.

[0042] See also Figure 1 , this figure is a schematic flow chart of a method for checking the symmetry of power distribution in a hexagonal core of a nuclear power plant provided in an embodiment of the present application.

[0043] An embodiment of the present application provides a method for checking the symmetry of power distribution in a hexagonal core, comprising:

[0044] S101: After the reactor power meets a preset power threshold and reaches a xenon equilibrium state, a power peak factor Kq of the fuel assemblies in each symmetrical group of the hexagonal core is obtained.

[0045] In the embodiment of the present application, the hexagonal core is pre-divided into multiple sectors; the fuel assemblies in the symmetrical group are selected from the symmetrical positions of each sector. As an example, Figure 2 The schematic diagram of the nuclear fuel assembly loading arrangement of a hexagonal core of a nuclear power plant in an embodiment of the present application is shown. The 163 fuel assembly loading areas of the core are divided into symmetrical groups. For a hexagonal core, the groups can generally be divided according to 60° symmetry, that is, the core is divided into 6 sectors, and a position is symmetrically selected in each sector as a symmetrical group, totaling 28 groups, as shown in Table 1;

[0046] Table 1 The hexagonal core of a nuclear power plant is divided into symmetry groups with 60° symmetry

[0047]

[0048]

[0049] In some possible implementations of the present application, the fuel assemblies in the symmetric group can be selected from the symmetric positions of each sector, and the fuel assemblies of the same type can be integrated into the same symmetric group. When only the main regulating rod group is inserted into the core, the 28 60° symmetric groups can be further integrated, that is, divided into groups according to 30° symmetry. The symmetry of different types of nuclear fuel assemblies relative to the main regulating rod bundle needs to be considered. Figure 2 Taking the core loading as an example, it can be divided into 19 30° symmetry groups, as shown in Table 2. When only the main regulating rod group is inserted into the core, the symmetry check can be performed according to the 30° symmetry division group, which can expand the comparison range of some core areas and thus improve the reliability of the symmetry check.

[0050] Table 2 The hexagonal core of a nuclear power plant is divided into symmetry groups with 30° symmetry

[0051]

[0052]

[0053] When the regulating rod group other than the main regulating rod group is inserted into the core, the symmetry check can be performed by dividing the rods into groups with 60° symmetry. When only the main regulating rod group is inserted into the core, the symmetry check can be performed by dividing the rods into groups with 30° symmetry, which can expand the comparison range of some core areas and thus improve the reliability of the symmetry check. Figure 3 shown.

[0054] In one example, before step S101, it may also include: confirming that the core measurement system works normally, and the neutron flux detectors arranged in the reactor need to be more than 90% available. For example, 54×7 neutron flux detectors are arranged in the reactor, that is, 54 groups of 7 neutron flux detectors are evenly arranged along the height of the fuel assembly, and the available number needs to be no less than 341.

[0055] In practical applications, after the reactor power meets the preset power threshold and reaches the xenon equilibrium state, the reactor power may be not less than 40% of the rated power to reach the xenon equilibrium state, which is not limited here.

[0056] In some possible implementations of the embodiment of the present application, step S101 may further include:

[0057] It is determined whether the power peak factor of each fuel assembly is less than the power peak factor boundary value corresponding to the reactor power; if so, step S102 is executed; if not, it is considered that the power peak factor monitoring of the corresponding fuel assembly is unreliable.

[0058] For example, Figure 2 The example shown checks the reliability of Kq monitoring at the only 08-29 position in the first symmetry group. Figure 4 When the boundary values ​​shown change with power, the Kq monitoring at the 08-29 position is considered reliable. Figure 4 The horizontal axis is the reactor power, and the vertical axis is the Kq boundary value. For example, when the reactor power is 100% of the rated power, the Kq at any position in the core should be less than 1.35. It is determined whether the power peak factor of each fuel assembly is less than 1.35, otherwise the Kq monitoring at the corresponding position is considered unreliable. Then, check the reliability of Kq monitoring at a total of 6 symmetrical positions in the second symmetrical group, namely 08-31, 09-30, 09-28, 08-27, 07-28, and 07-30. Confirm one by one that the Kq at the above 6 symmetrical positions is less than 1.35, otherwise the Kq monitoring at the corresponding position is considered unreliable.

[0059] S102: Determine the absolute value of the difference between the power peak factor of each fuel assembly in each symmetrical group and the average value of the power peak factor of the fuel assemblies in the symmetrical group, and obtain the relative power deviation of each fuel assembly in the hexagonal core.

[0060] In the embodiment of the present application, the average value of the power peak factor can be calculated according to the following formula (1):

[0061]

[0062] In the formula, aveKq i is the average value of Kq of all symmetric positions in the i-th symmetry group, Kq ijis the Kq of the jth symmetry position in the i-th symmetry group; n is the total number of symmetry positions in the symmetry group.

[0063] The relative power deviation can be calculated according to the following formula (2):

[0064] △Kq ij =|Kq ij -aveKq i | (2)

[0065] In the formula, ΔKq ij It is the absolute value of the difference between the Kq of the jth symmetric position in the i-th symmetric group and the average value of the Kq of all symmetric positions in the i-th symmetric group.

[0066] S103: Determine whether the hexagonal core has good symmetry based on the relative power deviation and the average power peak factor.

[0067] In the embodiments of the present application, in view of the particularity of the hexagonal core loading method, the fuel assembly loading area in the core is divided into several symmetrical groups in different symmetrical ways to check the relative deviation of the power peak factor of the fuel assembly, and the boundary value and relative deviation evaluation standard of the power peak factor of the fuel assembly are given, which provides a method for checking the power distribution symmetry of the hexagonal core of a nuclear power plant during the power operation stage, can assist in judging the safety status of the reactor, and provide technical guarantee for the safe and stable operation of the nuclear power unit.

[0068] In some possible implementations of the embodiment of the present application, step S103 may specifically include:

[0069] According to the average power peak factor of the symmetrical group fuel assemblies, the relative power deviation threshold of each symmetrical group is determined; and it is judged whether the relative power deviation of each fuel assembly is not greater than the relative power deviation threshold of the corresponding symmetrical group.

[0070] As an example, when the average power peak factor of the symmetrical group of fuel assemblies is greater than 1.1, the relative power deviation threshold of the symmetrical group is 0.1; when the average power peak factor of the symmetrical group of fuel assemblies is not greater than 1.1, the relative power deviation threshold of the symmetrical group is 0.25.

[0071] In the embodiment of the present application, the symmetry of the power distribution of the hexagonal core can be determined by the following method.

[0072] 1) The Kq of the entire core is less than the boundary value at the corresponding power level;

[0073] 2) ΔKq of the whole core ij≤△. When aveKq of the symmetry group to which a certain symmetric position in the core belongs is greater than 1.1, then △=0.1; when aveKq of the symmetry group to which a certain symmetric position in the core belongs is less than 1.1, then △=0.25.

[0074] If the above conditions 1) and 2) are met, it can be judged that the hexagonal core power distribution has good symmetry.

[0075] A method for checking the symmetry of power distribution in a hexagonal core of a nuclear power plant provided in an embodiment of the present application divides the fuel assembly loading area in the core into a number of symmetry groups in different symmetry methods in view of the particularity of the hexagonal core loading method, so as to check the relative deviation of the power peak factor of the fuel assembly, and provides the boundary value and relative deviation evaluation standard of the power peak factor of the fuel assembly, thereby providing a method for checking the symmetry of power distribution in the hexagonal core of a nuclear power plant during the power operation stage, which can assist in judging the safety status of the reactor and provide technical guarantee for the safe and stable operation of the nuclear power unit.

[0076] Based on the method for checking the symmetry of power distribution in a hexagonal core provided in the above-mentioned embodiment, an embodiment of the present application further provides a device for checking the symmetry of power distribution in a hexagonal core.

[0077] See also Figure 5 , this figure is a structural schematic diagram of a nuclear power plant hexagonal core power distribution symmetry inspection device provided in an embodiment of the present application.

[0078] An embodiment of the present application provides a hexagonal core power distribution symmetry inspection device, comprising: an acquisition module 100, a determination module 200 and a first judgment module 300;

[0079] The obtaining module 100 is used to obtain the power peak factor of the fuel assemblies in each symmetrical group of the hexagonal core after the reactor power meets the preset power threshold and reaches the xenon equilibrium state; the hexagonal core is pre-divided into a plurality of sectors; the fuel assemblies in the symmetrical group are respectively selected from the symmetrical positions of each sector;

[0080] A determination module 200 is used to determine the absolute value of the difference between the power peak factor of each fuel assembly in each symmetrical group and the average power peak factor of the fuel assemblies in the symmetrical group, and obtain the relative power deviation of each fuel assembly in the hexagonal core;

[0081] The first judgment module 300 is used to judge whether the hexagonal core has good symmetry according to the relative power deviation and the average power peak factor.

[0082] In some possible implementations of the embodiments of the present application, the device may further include: a second judgment module;

[0083] The second judgment module is used to judge whether the power peak factor of each fuel assembly is less than the power peak factor boundary value corresponding to the reactor power;

[0084] The determination module is specifically used to determine the absolute value of the difference between the power peak factor of each fuel assembly in each symmetric group and the average value of the power peak factor of the symmetric group when the judgment result of the second judgment module is yes.

[0085] In some possible implementations of the embodiments of the present application, the first determination module 300 is specifically configured to:

[0086] Determining a relative power deviation threshold of each symmetrical group according to an average power peak factor of the symmetrical group fuel assemblies;

[0087] It is determined whether the relative power deviation of each fuel assembly is not greater than the relative power deviation threshold of the corresponding symmetric group.

[0088] In some possible implementations of the embodiments of the present application, when the average power peak factor of the symmetrical group of fuel assemblies is greater than 1.1, the relative power deviation threshold of the symmetrical group is 0.1; when the average power peak factor of the symmetrical group of fuel assemblies is not greater than 1.1, the relative power deviation threshold of the symmetrical group is 0.25.

[0089] An embodiment of the present application provides a device for checking the symmetry of power distribution in a hexagonal core of a nuclear power plant. In view of the particularity of the hexagonal core loading method, the fuel assembly loading area in the core is divided into several symmetry groups in different symmetry methods to check the relative deviation of the power peak factor of the fuel assembly, and the boundary value and relative deviation evaluation standard of the power peak factor of the fuel assembly are given. This provides a method for checking the symmetry of power distribution in the hexagonal core of a nuclear power plant during the power operation stage, can assist in judging the safety status of the reactor, and provide technical guarantee for the safe and stable operation of the nuclear power unit.

[0090] The present application is described in detail above in conjunction with the accompanying drawings and embodiments, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present application. Any content not described in detail in the present application can adopt the existing technology.

Claims

1. A method for checking the symmetry of power distribution in a hexagonal core, characterized in that: The method comprises: After the reactor power meets a preset power threshold and reaches a xenon equilibrium state, the power peak factor of the fuel assemblies in each symmetric group of the hexagonal core is obtained; the hexagonal core is pre-divided into a plurality of sectors; the fuel assemblies in the symmetric group are respectively selected from the symmetric positions of each of the sectors; Determine the absolute value of the difference between the power peak factor of each fuel assembly in each of the symmetrical groups and the average value of the power peak factor of the fuel assemblies in the symmetrical group, and obtain the relative power deviation of each fuel assembly in the hexagonal core; Whether the hexagonal core has good symmetry is determined according to the relative power deviation and the average power peak factor.

2. The method for checking the symmetry of power distribution in a hexagonal core according to claim 1, characterized in that: The fuel assemblies in the symmetric group are respectively selected from symmetrical positions of each of the sectors, and the fuel assemblies of the same type are integrated into the same symmetric group.

3. The method for checking the symmetry of power distribution in a hexagonal core according to claim 1 or 2, characterized in that: The step of obtaining the power peak factor of the fuel assemblies in each symmetrical group of the hexagonal core further comprises: Determining whether the power peak factor of each fuel assembly is less than the power peak factor boundary value corresponding to the reactor power; If yes, then determining the absolute value of the difference between the power peak factor of each fuel assembly in each of the symmetric groups and the average value of the power peak factor of the symmetric group is performed; If not, the power peak factor monitoring of the corresponding fuel assembly is considered unreliable.

4. The method for checking the symmetry of power distribution in a hexagonal core according to claim 3, characterized in that: The determining whether the power peak factor of each fuel assembly is less than the power peak factor boundary value corresponding to the reactor power specifically includes: When the reactor power is 100% of the rated power, it is determined whether the power peak factor of each fuel assembly is less than 1.

35.

5. The method for checking the symmetry of power distribution in a hexagonal core according to claim 3, characterized in that: The judging, according to the relative power deviation and the average power peak factor, whether the hexagonal core has good symmetry specifically includes: Determining a relative power deviation threshold of each of the symmetrical groups according to an average power peak factor of the symmetrical group fuel assemblies; It is determined whether the relative power deviation of each fuel assembly is not greater than the relative power deviation threshold of the corresponding symmetric group.

6. The method for checking the symmetry of power distribution in a hexagonal core according to claim 5, characterized in that: When the average power peak factor of the symmetrical group of fuel assemblies is greater than 1.1, the relative power deviation threshold of the symmetrical group is 0.1; when the average power peak factor of the symmetrical group of fuel assemblies is not greater than 1.1, the relative power deviation threshold of the symmetrical group is 0.

25.

7. A device for checking the symmetry of power distribution in a hexagonal core, characterized in that: The device comprises: an obtaining module, a determining module and a first judging module; The acquisition module is used to obtain the power peak factor of the fuel assemblies in each symmetric group of the hexagonal core after the reactor power meets the preset power threshold and reaches the xenon equilibrium state; the hexagonal core is pre-divided into a plurality of sectors; the fuel assemblies in the symmetric group are respectively selected from the symmetric positions of each of the sectors; The determination module is used to determine the absolute value of the difference between the power peak factor of each fuel assembly in each of the symmetrical groups and the average power peak factor of the fuel assemblies in the symmetrical group, so as to obtain the relative power deviation of each fuel assembly in the hexagonal core; The first judgment module is used to judge whether the hexagonal core has good symmetry according to the relative power deviation and the power peak factor average value.

8. The hexagonal core power distribution symmetry inspection device according to claim 7, characterized in that: The device further includes: a second judgment module; The second judgment module is used to judge whether the power peak factor of each fuel assembly is less than the power peak factor boundary value corresponding to the reactor power; The determination module is specifically configured to, when the judgment result of the second judgment module is yes, execute the determination of the absolute value of the difference between the power peak factor of each fuel assembly in each of the symmetric groups and the average power peak factor of the symmetric group.

9. The method for checking the symmetry of power distribution in a hexagonal core according to claim 7, characterized in that: The first judgment module is specifically used to: Determining a relative power deviation threshold of each of the symmetrical groups according to an average power peak factor of the symmetrical group fuel assemblies; It is determined whether the relative power deviation of each fuel assembly is not greater than the relative power deviation threshold of the corresponding symmetric group.

10. The method for checking the symmetry of power distribution in a hexagonal core according to claim 9, characterized in that: When the average power peak factor of the symmetrical group of fuel assemblies is greater than 1.1, the relative power deviation threshold of the symmetrical group is 0.1; when the average power peak factor of the symmetrical group of fuel assemblies is not greater than 1.1, the relative power deviation threshold of the symmetrical group is 0.25.

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