Fuel assembly line power density determination method and apparatus, and computer device

Abstract

The present application relates to a fuel assembly line power density determination method and apparatus, a computer device, a storage medium and a computer program product. The method comprises: acquiring state signals of neutron detectors at a preset height in each thimble tube in a first thimble tube group corresponding to a fuel assembly to be measured, said fuel assembly being surrounded by a plurality of thimble tube groups corresponding thereto with said fuel assembly as the center, and each thimble tube group comprising a plurality of thimble tubes; when determining, on the basis of the state signals, that the neutron detectors at the preset height in each thimble tube in the first thimble tube group are all abnormal, determining a second thimble tube group corresponding to said fuel assembly; selecting at least one effective thimble tube from the second thimble tube group to serve as a target thimble tube; and, on the basis of data measured by the neutron detectors located at the preset height in the target thimble tube, determining the linear power density of said fuel assembly. The method can improve the accuracy of the line power density.

Description

Method, device and computer equipment for determining fuel assembly linear power density

[0001] Cross-references

[0002] This application refers to Chinese Patent Application No. 2023116149392, filed on November 29, 2023, entitled “Method, device and computer equipment for determining linear power density of fuel assemblies”, which is incorporated into this application in its entirety by reference. Technical Field

[0003] The present application relates to the field of nuclear energy technology, and in particular to a method, apparatus, computer equipment, storage medium, and computer program product for determining the linear power density of a fuel assembly. Background Art

[0004] With the development of nuclear engineering technology, in order to ensure the safety of the reactor, it is necessary to continuously monitor the power distribution in the reactor along three spatial dimensions.

[0005] Traditional methods for reconstructing core power include thin-plate spline fitting, polynomial expansion, and ordinary kriging. For example, the polynomial expansion method collects measurement data from the reactor, then divides the reactor geometry into multiple grids. Within each grid, a polynomial is used to represent the three-dimensional power distribution of the core. Based on the principles of polynomial expansion, an optimization algorithm is used to determine the optimal polynomial coefficients. These coefficients are then substituted into a pre-defined polynomial function to estimate the core power distribution.

[0006] However, in the event of neutron detector failure, the data of a certain grid in the polynomial expansion method will be missing or erroneous, resulting in a decrease in data continuity and a reduction in the accuracy of the linear power density of the fuel assembly.

[0007] Summary of the Invention

[0008] Based on this, it is necessary to provide a method, device, computer equipment, computer-readable storage medium and computer program product for determining the linear power density of a fuel assembly that can improve the accuracy of the linear power density in order to address the above technical problems.

[0009] In a first aspect, the present application provides a method for determining the linear power density of a fuel assembly. The method comprises: obtaining a status signal of a neutron detector at a preset height for each finger-tube in a first finger-tube group corresponding to the fuel assembly to be tested; with the fuel assembly to be tested as the center, multiple finger-tube groups corresponding to the fuel assembly to be tested are arranged around the fuel assembly to be tested, each finger-tube group including multiple finger-tubes; if, based on the status signals, it is determined that the neutron detectors at the preset height in each finger-tube in the first finger-tube group are abnormal, determining a second finger-tube group corresponding to the fuel assembly to be tested; the distance between each finger-tube in the second finger-tube group and the fuel assembly to be tested is greater than the distance between each finger-tube in the first finger-tube group and the fuel assembly to be tested; selecting at least one valid finger-tube from the second finger-tube group as a target finger-tube; the neutron detector at the preset height in the valid finger-tube is normal; and determining the linear power density of the fuel assembly to be tested based on data detected by the neutron detector at the preset height in the target finger-tube.

[0010] In a second aspect, the present application also provides a device for determining the linear power density of a fuel assembly. The system comprises: a signal acquisition module for acquiring a status signal of a neutron detector at a preset height of each finger-tube in a first finger-tube group corresponding to a fuel assembly to be tested; a plurality of finger-tube groups corresponding to the fuel assembly to be tested are arranged around the fuel assembly to be tested, each finger-tube group including a plurality of finger-tubes; a first selection module for determining, upon determining, based on the status signals, that the neutron detectors at the preset height in each finger-tube in the first finger-tube group are abnormal, a second finger-tube group corresponding to the fuel assembly to be tested; the distance between each finger-tube in the second finger-tube group and the fuel assembly to be tested being greater than the distance between each finger-tube in the first finger-tube group and the fuel assembly to be tested; a second selection module for selecting at least one valid finger-tube from the second finger-tube group as a target finger-tube; the neutron detector at the preset height in the valid finger-tube being in a normal state; and a linear power density determination module for determining the linear power density of the fuel assembly to be tested based on data detected by the neutron detector at the preset height in the target finger-tube.

[0011] In some embodiments, the linear power density determination module is further configured to obtain, for each selected target finger sleeve, the axial linear power of the target finger sleeve determined at the preset height based on data detected by the neutron detector at the preset height in the target finger sleeve; and determine the linear power density of the fuel assembly to be tested based on the axial linear power determined for each selected target finger sleeve at the preset height.

[0012] In some embodiments, the linear power density determination module is further configured to determine a weight corresponding to each selected target finger sleeve; based on the weight corresponding to each selected target finger sleeve, weight the axial linear power determined for each selected target finger sleeve at the preset height to obtain the linear power density of the fuel assembly to be tested.

[0013] In some embodiments, the linear power density determination module is further configured to determine, for each selected target finger sleeve, a weight corresponding to the target finger sleeve based on the distance between the target finger sleeve and the fuel assembly to be tested; wherein the distance between the target finger sleeve and the fuel assembly to be tested is negatively correlated with the weight corresponding to the target finger sleeve.

[0014] In some embodiments, the linear power density determination module is further configured to, when it is determined based on each of the status signals that the neutron detector located at a preset height in at least one finger-tube in the first finger-tube group is in a normal state, select at least one valid finger-tube from the first finger-tube group as a standard finger-tube; and determine the linear power density of the fuel assembly to be tested based on the axial linear powers determined for the standard finger-tubes at the preset height.

[0015] In some embodiments, the linear power density determination module is further configured to, when there are multiple valid finger sleeves in the first finger sleeve group, select a first number of the valid finger sleeves from the multiple valid finger sleeves in the first finger sleeve group as the standard finger sleeves; wherein the first number is less than or equal to a second number, and the second number is the number of finger sleeves in the finger sleeve group closest to the fuel assembly to be tested; and the distance between each finger sleeve in the closest finger sleeve group and the fuel assembly to be tested is less than the distance between each finger sleeve in other finger sleeve groups corresponding to the fuel assembly to be tested and the fuel assembly to be tested.

[0016] In a third aspect, the present application further provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps in the above-mentioned method for determining the linear power density of a fuel assembly when executing the computer program.

[0017] In a fourth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps in the above-mentioned method for determining the linear power density of a fuel assembly.

[0018] In a fifth aspect, the present application further provides a computer program product, comprising a computer program that, when executed by a processor, implements the steps in the above-mentioned method for determining the linear power density of a fuel assembly.

[0019] The above-mentioned method, apparatus, computer device, storage medium, and computer program product for determining the linear power density of a fuel assembly obtain a status signal of a neutron detector at a preset height for each finger-tube in a first finger-tube group corresponding to the fuel assembly to be tested; with the fuel assembly to be tested as the center, multiple finger-tube groups corresponding to the fuel assembly to be tested are arranged around the fuel assembly to be tested, each finger-tube group including multiple finger-tubes; if it is determined based on the status signals that the neutron detectors at the preset height in each finger-tube in the first finger-tube group are abnormal, a second finger-tube group corresponding to the fuel assembly to be tested is determined; the distance between each finger-tube in the second finger-tube group and the fuel assembly to be tested is greater than the distance between each finger-tube in the first finger-tube group and the fuel assembly to be tested; at least one valid finger-tube in the second finger-tube group is selected as a target finger-tube; and the linear power density of the fuel assembly to be tested is determined based on data detected by the neutron detectors at the preset height in the target finger-tube. When the neutron detectors closer to each fuel assembly are abnormal, the calculation error of the linear power density of each fuel assembly can be reduced by using the data obtained from the neutron detectors farther away from each fuel assembly, thereby improving the accuracy of the linear power density.

[0020] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the embodiments below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to denote the same components. In the drawings:

[0022] FIG1 is a diagram illustrating an application environment of a method for determining linear power density of a fuel assembly according to an embodiment;

[0023] FIG2 is a schematic flow chart of a method for determining linear power density of a fuel assembly according to one embodiment;

[0024] FIG3 is a schematic flow chart of a step of determining linear power density in one embodiment;

[0025] FIG4 is a schematic diagram showing the distribution of fuel assemblies and finger sleeves to be tested in one embodiment;

[0026] FIG5 is a structural block diagram of a device for determining linear power density of a fuel assembly according to one embodiment;

[0027] FIG6 is a diagram showing the internal structure of a computer device according to one embodiment;

[0028] FIG7 is a diagram showing the internal structure of a computer device in another embodiment. DETAILED DESCRIPTION

[0029] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0031] The method for determining the linear power density of a fuel assembly provided in an embodiment of the present application can be applied in the application environment shown in Figure 1 . Computer device 102 collects information related to the fuel assembly to be tested, and a data storage system can store the data that computer device 102 needs to process. The data storage system can be integrated with computer device 102 or located in the cloud or on other network servers.

[0032] Specifically, the computer device 102 obtains status signals from neutron detectors at a preset height for each finger-tube in a first finger-tube group corresponding to the fuel assembly 104 under test. Multiple finger-tube groups surround the fuel assembly under test, with the fuel assembly under test 104 as the center. Each finger-tube group includes multiple corresponding finger-tubes. If the computer device 102 determines, based on the status signals, that the neutron detectors at the preset height in each finger-tube in the first finger-tube group are abnormal, it then determines a second finger-tube group corresponding to the fuel assembly 104 under test. The distance between each finger-tube in the second finger-tube group and the fuel assembly 104 under test is greater than the distance between each finger-tube in the first finger-tube group and the fuel assembly 104 under test. The computer device 102 selects at least one valid finger-tube from the second finger-tube group as a target finger-tube. Based on the data detected by the neutron detectors at the preset height in the target finger-tube, the computer device 102 can determine the linear power density of the fuel assembly 104 under test.

[0033] The computer device 102 can be either a terminal or a server. Terminals include, but are not limited to, various measurement devices, personal computers, laptops, smartphones, tablets, IoT devices, and portable wearable devices. IoT devices include smart speakers, smart TVs, smart air conditioners, and smart car devices. Portable wearable devices include smart watches, smart bracelets, and head-mounted devices. The server can be implemented as a standalone server or a server cluster consisting of multiple servers.

[0034] In an exemplary embodiment, as shown in FIG2 , a method for determining the linear power density of a fuel assembly is provided. The method is described by taking the computer device 102 in FIG1 as an example, and includes the following steps 202 to 208 .

[0035] in:

[0036] Step 202: Acquire a neutron detector status signal of each finger-tube in a first finger-tube group corresponding to the fuel assembly to be tested at a preset height. The fuel assembly to be tested is centered, and there are multiple finger-tube groups corresponding to the fuel assembly to be tested, each finger-tube group including multiple finger-tubes.

[0037] Among them, the fuel assembly is a structure for placing and storing nuclear fuel. The fuel assembly is the basic unit that constitutes the core. Multiple fuel assemblies are arranged in the core to form a specific geometric structure. The fuel assembly to be tested is the fuel assembly whose linear power density is to be determined. The core is the core area of ​​the reactor. The reactor also includes components such as the reactor vessel, coolant system, and control system. The finger tube is a core neutron flux tube used to measure and monitor the neutron flux distribution in the nuclear reactor. The finger tube group is a collection of multiple finger tubes around the fuel assembly to be tested. The status signal is a signal that reflects the operating status of the neutron detector. Multiple means at least two. A neutron detector is a device used to detect the presence and characteristics of neutrons, including various types such as self-powered neutron detectors (SPND).

[0038] The fuel assembly to be tested can be in any shape such as cylindrical, rod-shaped, tubular, plate-shaped, and spherical, and is not limited here. In the embodiment of the present application, a cylindrical fuel assembly is used. The reactor contains multiple fuel assemblies and multiple finger sleeves. With the fuel assembly whose linear power density is to be determined (i.e., the fuel assembly to be tested hereinafter) as the center, the multiple finger sleeves can be divided into multiple finger sleeve groups corresponding thereto. It should be noted that in some embodiments, the reactor may include multiple categories of finger sleeves, and finger sleeves of the same category are connected to the same equipment, such as a cabinet. Among the multiple finger sleeve groups corresponding to the fuel assembly to be tested, at least two finger sleeves in the same finger sleeve group belong to different categories, that is, are connected to at least two different equipment. If all the finger sleeves in the same finger sleeve group are connected to the same device, all the detectors in the finger sleeve group connected to it will fail when the device is damaged. In this embodiment, since at least two finger sleeves in the same finger sleeve group belong to different categories, that is, they are connected to at least two different devices, this can prevent the failure of all neutron detectors in the entire finger sleeve group due to a failure of a certain device.

[0039] Multiple finger-tube groups surrounding the fuel assembly to be tested can be ranked according to the distance between the finger-tube group and the fuel assembly to be tested. The greater the distance, the higher the rank. The distance between a finger-tube group and the fuel assembly to be tested refers to the distance between the finger-tubes in the finger-tube group and the fuel assembly to be tested. In some embodiments, any group among the multiple finger-tube groups can be selected as the first finger-tube group corresponding to the fuel assembly to be tested. For example, the group of finger-tube groups closest to the fuel assembly to be tested is designated as the first finger-tube group. Each finger-tube group includes at least one finger-tube. In some embodiments, all finger-tubes in the same finger-tube group have the same distance from the fuel assembly to be tested.

[0040] Each finger sleeve is provided with multiple neutron detectors. The height of each neutron detector on the finger sleeve is predetermined. The predetermined height can be any predetermined height, and each finger sleeve is provided with a neutron detector at the predetermined height. For example, n different predetermined heights are predetermined, namely z1, z2, ..., zn. Where zi is the i-th predetermined height, and 1≤i≤n.

[0041] All finger sleeves around each fuel assembly have multiple neutron detectors at preset axial heights. The neutron detectors are used to detect the neutron flux density at the corresponding preset axial heights, and the probe structure inside the neutron detectors is used to determine the operating status of the neutron detectors themselves.

[0042] The operating status of a neutron detector can be represented by a status signal. Status signals are classified into normal and abnormal signals. A normal status signal indicates that the neutron detector is functioning normally, while an abnormal status signal indicates that the neutron detector is not functioning normally. The status signal of a neutron detector with the jth finger cannula at the i-th preset height can be represented as s(aj,i), where aj refers to the jth finger cannula in the cannula group and i refers to the i-th preset height. When the status signal is a first preset value, the neutron detector is functioning normally. When the status signal is a second preset value, the neutron detector is abnormal. The first preset value and the second preset value are different. For example, the first preset value is 1 and the second preset value is 0, or the first preset value is 0 and the second preset value is 1.

[0043] Specifically, in some embodiments, the state of the neutron detector can also be determined based on the data detected by the neutron detector. For example, when the neutron detector detects abnormal data, such as data 0, it can be considered that the neutron detector is in an abnormal state.

[0044] In some embodiments, the computer device selects a first finger-quill group from around the fuel assembly to be tested, and obtains a status signal of a neutron detector corresponding to each finger-quill in the first finger-quill group at a preset axial height.

[0045] Step 204: If it is determined based on the status signals that the neutron detectors at the preset height in each finger-tube in the first finger-tube group are abnormal, a second finger-tube group corresponding to the fuel assembly to be tested is determined; the distance between each finger-tube in the second finger-tube group and the fuel assembly to be tested is greater than the distance between each finger-tube in the first finger-tube group and the fuel assembly to be tested.

[0046] The second finger-tube group is one of multiple finger-tube groups surrounding the fuel assembly to be tested, but is different from the first finger-tube group. The distance between each finger-tube group and the fuel assembly to be tested is greater than the distance between each finger-tube group and the fuel assembly to be tested in the first finger-tube group. For example, in some embodiments, each finger-tube group surrounding the fuel assembly to be tested may correspond to a level, where the level is determined by the distance between the finger-tube group and the fuel assembly to be tested, with a greater distance indicating a higher level. Therefore, the second finger-tube group may be selected from finger-tube groups with a higher level than the first finger-tube group. For example, if the first finger-tube group corresponds to level 1, and there are five levels of finger-tube groups surrounding the fuel assembly to be tested, the second finger-tube group may be selected from the finger-tube groups corresponding to levels 2 through 5.

[0047] Specifically, the computer device uses the probe structure within the neutron detector to determine the operating status of the neutron detector. If the probe structure within the neutron detector detects that the neutron detectors of all finger-tubes in the first finger-tube group are abnormal at a preset axial height, the computer device may select a second finger-tube group. The computer device then selects another finger-tube group, other than the first finger-tube group, surrounding the fuel assembly to be tested as the second finger-tube group. For example, assuming the fuel assembly to be tested is numbered k and has a preset height zi, if the neutron detector status signals of all finger-tubes in the first finger-tube group are abnormal at the preset axial height zi, the second finger-tube group is selected around the fuel assembly to be tested. The distance between each finger-tube in the second finger-tube group and the fuel assembly to be tested is the same, and the distance between each finger-tube in the second finger-tube group and the fuel assembly to be tested is greater than the distance between each finger-tube in the first finger-tube group and the fuel assembly to be tested.

[0048] Furthermore, in some embodiments, the second finger tube group may be the valid finger tube group closest to the first finger tube group among the valid finger tube groups surrounding the fuel assembly to be tested. A valid finger tube group refers to a finger tube group having at least one valid finger tube.

[0049] If the neutron detector at a preset height in a particular finger-tube is in a normal state, then that finger-tube can be considered a valid finger-tube. Similarly, if at least one finger-tube in a group of finger-tubes is in a normal state, that is, if at least one neutron detector at a preset height in that group is in a normal state, then that group can be considered a valid finger-tube group. If the neutron detector at the preset height in every finger-tube in a first finger-tube group is abnormal, that is, if no finger-tube exists in the first finger-tube group, then the first finger-tube group is not a valid finger-tube group. In this case, the second finger-tube group can be the valid finger-tube group closest to the first finger-tube group among the valid finger-tube groups surrounding the fuel assembly to be tested.

[0050] Specifically, in some embodiments, when the neutron detector at a preset height in each finger-tube in the first finger-tube group is abnormal, all finger-tube groups whose distances to the fuel assembly to be tested are greater than the distance between the first finger-tube group and the fuel assembly to be tested may be selected first. Subsequently, the finger-tube group closest to the first finger-tube group is selected from the selected multiple finger-tube groups, and a determination is made as to whether the selected finger-tube group is a valid finger-tube group. If so, the finger-tube group is used as the second finger-tube group. Otherwise, the finger-tube group second closest to the first finger-tube group is selected from the selected multiple finger-tube groups, and the above determination steps are repeated.

[0051] For example, in some embodiments, each finger-tube group surrounding the fuel assembly to be tested may correspond to a hierarchy. The hierarchy is determined by the distance between the finger-tube group and the fuel assembly to be tested, with the greater the distance, the higher the hierarchy. In this case, a second finger-tube group can be determined from each finger-tube group other than the first finger-tube group in ascending hierarchy order. Specifically, an iterative approach can be used to determine the second finger-tube group. The hierarchy corresponding to the first finger-tube group is used to determine an initial hierarchy. Hierarchies adjacent to and higher than the initial hierarchy are then determined as candidate hierarchies. For example, if the hierarchy of the first finger-tube group is 1, the candidate hierarchy is 2. Obtain a finger-casing tube group corresponding to a candidate level to obtain a candidate finger-casing tube group. If the neutron detectors located at a preset height in each of the candidate finger-casing tubes are in an abnormal state, it can be considered that the candidate finger-casing tube group is not a valid finger-casing tube group. Then, a level adjacent to and higher than the candidate level is determined as a candidate level for the next round, and the process returns to the step of obtaining the finger-casing tube group corresponding to the candidate level and obtaining the candidate finger-casing tube group to find a new candidate finger-casing tube group. If there is a finger-casing tube in the candidate finger-casing tube group whose neutron detector at the preset height is in a normal state, it can be considered that the candidate finger-casing tube group is a valid finger-casing tube group. Then, the candidate finger-casing tube group is determined as the second finger-casing tube group.

[0052] Of course, in some embodiments, it is also possible to first select all valid finger-tube-tube groups whose distances to the fuel assembly to be tested are greater than the distance between the first finger-tube-tube group and the fuel assembly to be tested, and then select the valid finger-tube-tube group closest to the first finger-tube-tube group as the second finger-tube-tube group. This is not a limitation herein.

[0053] In this embodiment, since the second finger-quill group is the effective finger-quill group closest to the first finger-quill group, the error caused by the increased distance between the finger-quill group and the fuel assembly can be reduced, thereby improving the accuracy of the linear power density.

[0054] Step 206: Select at least one valid finger tube from the second finger tube group as a target finger tube; the neutron detector located at a preset height in the valid finger tube is in a normal state.

[0055] The target finger tube belongs to the second finger tube group, and the neutron detector at the preset height in the target finger tube is in a normal state.

[0056] Specifically, the computer device selects at least one valid finger cuff from the second finger cuff group as the target finger cuff. For example, the computer device may select one valid finger cuff from the second finger cuff group as the target finger cuff. Alternatively, the computer device may select all valid finger cuffs from the second finger cuff group as the target finger cuff.

[0057] It should be noted that in some embodiments, in order to obtain a more accurate linear power density of the fuel assembly to be tested, it is necessary to perform calculations based on data detected by a preset number of neutron detectors. If the number of neutron detectors in the second finger-tube group located at a preset height that are in a normal state exceeds the preset number, that is, the number of valid finger-tubes in the second finger-tube group is greater than the preset number, then a preset number of valid finger-tubes are selected from the second finger-tube group as target finger-tubes. If the number of neutron detectors in the second finger-tube group located at a preset height that are in a normal state is less than the preset number, that is, the number of valid finger-tubes in the second finger-tube group is less than the preset number, then all valid finger-tubes in the second finger-tube group may be selected as target finger-tubes.

[0058] Step 208 : Determine the linear power density of the fuel assembly to be tested based on the data detected by the neutron detector located at a preset height in the target finger sleeve.

[0059] The linear power density is the power output per unit length of the fuel assembly under test. The data detected by the neutron detector include neutron intensity, neutron flux density, and neutron energy spectrum.

[0060] Specifically, the computer device analyzes and calculates the data detected by the neutron detector at the preset height of the target finger-tube selected from the second finger-tube group to obtain the linear power density of the fuel assembly to be tested.

[0061] In some embodiments, the neutron detector can detect the neutron flux density at a preset height, and the computer device can calculate the axial linear power of the ferrule at a preset axial height based on the neutron flux density, and calculate the linear power density of the fuel assembly to be tested based on each axial linear power.

[0062] In the above-mentioned method for determining the linear power density of a fuel assembly, a status signal of a neutron detector at a preset height for each finger-tube in a first finger-tube group corresponding to the fuel assembly to be tested is obtained. With the fuel assembly to be tested as the center, multiple finger-tube groups corresponding to the fuel assembly to be tested are located around the fuel assembly to be tested, each finger-tube group including multiple finger-tubes. If, based on the status signals, it is determined that the neutron detectors at the preset height in each finger-tube in the first finger-tube group are abnormal, a second finger-tube group corresponding to the fuel assembly to be tested is determined, the distance between each finger-tube in the second finger-tube group and the fuel assembly to be tested is greater than the distance between each finger-tube in the first finger-tube group and the fuel assembly to be tested. At least one valid finger-tube from the second finger-tube group is selected as a target finger-tube. The linear power density of the fuel assembly to be tested is determined based on data detected by the neutron detectors at the preset height in the target finger-tube. When the neutron detectors closer to each fuel assembly are abnormal, the calculation error of the linear power density of each fuel assembly can be reduced by using the data obtained from the neutron detectors farther away from each fuel assembly, thereby improving the accuracy of the linear power density.

[0063] In an exemplary embodiment, as shown in FIG3 , step 208 includes steps 302 to 304 .

[0064] Step 302 : For each selected target finger sleeve, based on the data detected by the neutron detector at the preset height in the target finger sleeve, obtain the axial line power determined at the preset height of the target finger sleeve.

[0065] The axial line power refers to the power transmitted by the casing at a preset height along a preset axial direction.

[0066] Specifically, the computer device calculates the axial line power of the target finger cannula selected from the second finger cannula group at a preset height based on the detected data. The detected data comes from a neutron detector set at the preset height of the target finger cannula selected from the second finger cannula group.

[0067] In some embodiments, the neutron detector can detect the neutron flux density of the target finger cannula at a preset height and, based on the correlation between the neutron flux density and the corresponding current data, obtain the current corresponding to the target finger cannula at the preset height. Based on the positive correlation between the current corresponding to the target finger cannula at the preset height and the axial linear power of the target finger cannula at the preset height, the axial linear power of the target finger cannula at the preset height can be calculated.

[0068] Step 304 : determining the linear power density of the fuel assembly to be tested based on the axial linear power determined for each selected target finger sleeve at a preset height.

[0069] The axial line power corresponds to the target finger sleeve in a one-to-one manner, and the axial line power corresponds to different heights of the target finger sleeve in a preset axial direction in a one-to-one manner.

[0070] Specifically, the computer device analyzes and calculates the axial linear powers of the target finger-quill tube selected from the second finger-quill tube group at a preset height based on the calculated axial linear powers to obtain the linear power density of the fuel assembly to be tested corresponding to the target finger-quill tube.

[0071] In this embodiment, the linear power density of the fuel assembly to be tested can be calculated using the data detected by the neutron detector, thereby improving the accuracy of the linear power density of the fuel assembly to be tested.

[0072] In some embodiments, determining the linear power density of the fuel assembly to be tested based on the axial linear powers respectively determined for each selected target finger sleeve at a preset height includes: determining a weight corresponding to each selected target finger sleeve; and weighting the axial linear powers respectively determined for each selected target finger sleeve at the preset height based on the weight corresponding to each selected target finger sleeve to obtain the linear power density of the fuel assembly to be tested.

[0073] Specifically, the computer determines the weight of each finger-and-socket surrounding the fuel assembly to be tested. Based on the weights corresponding to the different finger-and-sockets, the computer performs a weighted calculation on the axial linear power obtained at a preset height for each target finger-and-socket selected from the second finger-and-socket group to obtain the linear power density of the fuel assembly to be tested.

[0074] In some embodiments, there are multiple finger tube groups around the fuel assembly to be tested. All finger tubes in each finger tube group have the same weight, and the weights of finger tubes in different finger tube groups are different.

[0075] In this embodiment, by determining the weight corresponding to the target finger sleeve, the axial linear power of the target finger sleeve can be calculated based on the determined weight of the target finger sleeve, so that the linear power density of the fuel assembly to be tested is more accurate.

[0076] In some embodiments, determining a weight corresponding to each selected target finger sleeve includes: determining, for each selected target finger sleeve, a weight corresponding to the target finger sleeve based on a distance between the target finger sleeve and the fuel assembly to be tested; wherein the distance between the target finger sleeve and the fuel assembly to be tested is negatively correlated with the weight corresponding to the target finger sleeve.

[0077] Specifically, the computer device measures the distance between each target finger sleeve and the fuel assembly to be tested. Based on the negative correlation between the distance between the target finger sleeve and the fuel assembly to be tested and the weight corresponding to the target finger sleeve, the weight corresponding to each target finger sleeve can be obtained.

[0078] In this embodiment, by measuring the distance between the target finger sleeve and the fuel assembly to be tested, the weight corresponding to each target finger sleeve can be obtained, so that the calculation result of the linear power density of the fuel assembly to be tested is more accurate.

[0079] In some embodiments, the method for determining the linear power density of a fuel assembly further includes: when it is determined, based on each status signal (wherein each status signal refers to the status signal of the neutron detector at the preset height of each finger-tube in the first finger-tube group obtained above), that the neutron detector at the preset height in at least one finger-tube in the first finger-tube group is in a normal state; selecting at least one valid finger-tube from the first finger-tube group as a standard finger-tube; and determining the linear power density of the fuel assembly to be tested based on the axial linear power determined for the standard finger-tube at the preset height.

[0080] The standard finger sleeve belongs to the first finger sleeve group, and the neutron detector located at a preset height in the standard finger sleeve is in a normal state.

[0081] Specifically, the computer device uses a probe structure within the neutron detector to obtain a status signal of the neutron detector, thereby determining the operating status of the neutron detector at a preset height in the first finger-and-tube group. If it is determined that the neutron detector at the preset height in at least one finger-and-tube group in the first finger-and-tube group is operating normally, multiple finger-and-tubes are selected from the first finger-and-tube group, and the axial linear powers corresponding to the selected multiple finger-and-tubes at the preset height are calculated. Based on the axial linear powers corresponding to the selected finger-and-tubes, the linear power density of the fuel assembly under test at the preset height is determined. The neutron detector at the preset height in at least one finger-and-tube group selected from the first finger-and-tube group is operating normally.

[0082] In this embodiment, by determining the status of each finger-tube in the first finger-tube group, the linear power density of the fuel assembly to be tested can be obtained based on the data of the first finger-tube group, thereby improving the calculation efficiency of the linear power density of the fuel assembly to be tested.

[0083] In some embodiments, selecting at least one valid finger sleeve from the first finger sleeve group as a standard finger sleeve includes: if there are multiple valid finger sleeves in the first finger sleeve group, selecting a first number of valid finger sleeves from the multiple valid finger sleeves in the first finger sleeve group as the standard finger sleeves; wherein the first number is less than or equal to a second number, and the second number is the number of finger sleeves in the finger sleeve group closest to the fuel assembly to be tested; and the distance between each finger sleeve in the closest finger sleeve group and the fuel assembly to be tested is less than the distance between each finger sleeve in other finger sleeve groups corresponding to the fuel assembly to be tested and the fuel assembly to be tested.

[0084] The first number is the number of finger tubes selected from the first finger tube group for subsequent linear power density calculation. The second number is the number of finger tubes in the closest finger tube group surrounding the fuel assembly to be tested. The closest finger tube group is the finger tube group whose included finger tubes are closest to the fuel assembly to be tested, among all finger tube groups surrounding the fuel assembly to be tested.

[0085] Specifically, when the computer device determines that the neutron detector of at least one finger tube at a preset height in the first finger tube group is operating normally, the computer device selects a first number of finger tubes from the normally operating finger tubes in the first finger tube group.

[0086] In some embodiments, assuming there are six finger sleeves in the most recent finger sleeve group (i.e., the second number is 6), when calculating the linear power density of the fuel assembly under test, six finger sleeves can be selected from the first finger sleeve group, and the data from the six finger sleeves in the first finger sleeve group can be used for calculation. If the total number of finger sleeves included in the first finger sleeve group is greater than 6, only six finger sleeves are selected from the first finger sleeve group. Neutron detectors at the preset height of the six finger sleeves selected from the first finger sleeve group may not all function properly. That is, among the six finger sleeves selected from the first finger sleeve group, the first number of finger sleeves whose neutron detectors at the preset height function properly is the first number.

[0087] In this embodiment, by selecting a preset number of finger tubes from the first finger tube group, the linear power density can be calculated using the data of the selected finger tubes, thereby ensuring the accuracy of the linear power density calculation of the fuel assembly to be tested.

[0088] In some embodiments, as shown in FIG4 , a partial schematic diagram of a fuel assembly to be tested and its surrounding finger sleeves from a top view is shown. In the figure, the numbers 1-7 represent different rows, the letters R, P, N, M, L, K, J, and H represent different columns, and the letters A, B, C, and D represent a type of finger sleeve. Identical letters in A, B, C, and D represent the same type of finger sleeve. The shaded portion in row 4, column L in the figure represents the fuel assembly to be tested. Finger sleeve A in row 3, column M, finger sleeve B in row 3, column K, finger sleeve C in row 5, column M, and finger sleeve D in row 5, column K constitute the first-level finger sleeve group, which is the finger sleeve group closest to the fuel assembly to be tested. Finger tube A in row 1, column K, finger tube D in row 5, column P, finger tube A in row 5, column H, finger tube B in row 7, column M, finger tube C in row 7, column K, and finger tube B in row 3, column H constitute the second-level finger tube group. The second-level finger tube group is the finger tube group closest to the fuel assembly under test, excluding the first-level finger tube group. If at least one neutron detector at a preset height in finger tubes A, B, C, and D in the first-level finger tube group is functioning properly, the linear power density of the fuel assembly under test can be calculated by taking a weighted average of finger tubes A, B, C, and D in the first-level finger tube group using a weighted coefficient method. If all neutron detectors at the preset height in finger tubes A, B, C, and D in the first-level finger tube group are abnormal, the linear power density can be calculated by taking a weighted average of finger tubes A, B, C, and D in the second-level finger tube group using a weighted coefficient method.

[0089] Assume that the fuel assembly to be tested is numbered k. The nearest ring of finger sleeves surrounding the fuel assembly is composed of m finger sleeves, numbered a1, a2, ..., am. Each finger sleeve in the nearest ring is equipped with n neutron detectors at axial heights z1, z2, ..., zn. At a preset height zi, if the neutron detector status signals at axial height zi for all finger sleeves in the nearest ring are abnormal, a second outer ring of finger sleeves is selected around the fuel assembly to be tested, consisting of r (r ≥ m) finger sleeves, numbered b1, b2, ..., bm, ..., br. Finger sleeve bj (1 ≤ j ≤ r) is selected from the second finger sleeve group. Assume that the linear power density of the fuel assembly k under test at the axial height zi is Pk(i), and the reconstructed axial linear power of the finger sleeve bj at the height zi is Pk(bj,i). ω(k,bj) represents the weight of the finger sleeve bj in the calculation of the linear power density of the fuel assembly k under test. The state signal of the neutron detector of the finger sleeve bj at the axial height zi (1≤i≤n) is defined as s(bj,i). Therefore, the linear power density of the fuel assembly k under test at the preset height zi can be expressed as:

[0090] It should be understood that, although the various steps in the flowcharts involved in the various embodiments described above are displayed in sequence according to the instructions of the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the various embodiments described above can include multiple steps or multiple stages, and these steps or stages are not necessarily executed and completed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0091] Based on the same inventive concept, embodiments of the present application also provide a device for determining the linear power density of a fuel assembly, for implementing the aforementioned method for determining the linear power density of a fuel assembly. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more embodiments of the device for determining the linear power density of a fuel assembly provided below can be found in the aforementioned method for determining the linear power density of a fuel assembly, and will not be further elaborated here.

[0092] In an exemplary embodiment, as shown in FIG5 , a fuel assembly linear power density determination device is provided, comprising: a signal acquisition module 502 , a first selection module 504 , a second selection module 506 , and a linear power density determination module 508 , wherein:

[0093] Signal acquisition module 502 is configured to acquire a neutron detector status signal at a preset height for each finger-and-sleeve tube in a first finger-and-sleeve tube group corresponding to the fuel assembly to be tested. The fuel assembly to be tested is centered on the fuel assembly to be tested, and there are multiple finger-and-sleeve tube groups corresponding to the fuel assembly to be tested, each finger-and-sleeve tube group including multiple finger-and-sleeve tubes.

[0094] The first selection module 504 is configured to, if it is determined based on the status signals that the neutron detectors at the preset height in each finger-tube in the first finger-tube group are abnormal, determine a second finger-tube group corresponding to the fuel assembly to be tested; and the distance between each finger-tube in the second finger-tube group and the fuel assembly to be tested is greater than the distance between each finger-tube in the first finger-tube group and the fuel assembly to be tested;

[0095] The second selection module 506 is configured to select at least one valid finger cannula from the second finger cannula group as a target finger cannula; the neutron detector located at a preset height in the valid finger cannula is in a normal state;

[0096] The linear power density determination module 508 is configured to determine the linear power density of the fuel assembly to be tested based on data detected by the neutron detector located at a preset height in the target finger sleeve.

[0097] In some embodiments, the linear power density determination module is further configured to obtain, for each selected target finger sleeve, the axial linear power determined at the preset height of the target finger sleeve based on data detected by a neutron detector at a preset height in the target finger sleeve; and determine the linear power density of the fuel assembly to be tested based on the axial linear power determined for each selected target finger sleeve at the preset height.

[0098] In some embodiments, the linear power density determination module is further configured to determine a weight corresponding to each selected target finger sleeve; based on the weight corresponding to each selected target finger sleeve, the axial linear power determined for each selected target finger sleeve at a preset height is weighted to obtain the linear power density of the fuel assembly to be tested.

[0099] In some embodiments, the linear power density determination module is further configured to determine, for each selected target finger-and-tube, a weight corresponding to the target finger-and-tube based on the distance between the target finger-and-tube and the fuel assembly to be tested; wherein the distance between the target finger-and-tube and the fuel assembly to be tested is negatively correlated with the weight corresponding to the target finger-and-tube.

[0100] In some embodiments, the apparatus further includes a linear power density determination module configured to, when it is determined based on various status signals that a neutron detector located at a preset height in at least one finger-tube in the first finger-tube group is in a normal state, select at least one valid finger-tube from the first finger-tube group as a standard finger-tube; and determine the linear power density of the fuel assembly to be tested based on the axial linear power determined for the characteristic finger-tube at the preset height.

[0101] In some embodiments, the linear power density determination module is further configured to, when there are multiple valid finger-tubes in the first finger-tube group, select a first number of valid finger-tubes from the multiple valid finger-tubes in the first finger-tube group as standard finger-tubes; wherein the first number is less than or equal to a second number, where the second number is the number of finger-tubes in the finger-tube group closest to the fuel assembly to be tested; and the distance between each finger-tube in the closest finger-tube group and the fuel assembly to be tested is less than the distance between each finger-tube in other finger-tube groups corresponding to the fuel assembly to be tested and the fuel assembly to be tested.

[0102] Each module in the aforementioned apparatus for determining the linear power density of a fuel assembly may be implemented in whole or in part via software, hardware, or a combination thereof. Each module may be embedded in or independent of a processor within a computer device in the form of hardware, or may be stored in a computer device memory in the form of software, allowing the processor to call and execute the corresponding operations of each module.

[0103] In an exemplary embodiment, a computer device is provided, which may be a server. Its internal structure diagram may be as shown in FIG6 . The computer device includes a processor, memory, an input / output (I / O) interface, and a communication interface. The processor, memory, and I / O interface are connected via a system bus, and the communication interface is connected to the system bus via the I / O interface. The processor of the computer device provides computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operating system and computer program in the non-volatile storage medium. The database of the computer device stores session data. The I / O interface of the computer device is used to exchange information between the processor and external devices. The communication interface of the computer device is used to communicate with external terminals via a network connection. When executed by the processor, the computer program implements a method for determining the linear power density of a fuel assembly.

[0104] In an exemplary embodiment, a computer device is provided, which may be a terminal. Its internal structure may be shown in FIG7 . The computer device includes a processor, memory, an input / output interface, a communication interface, a display unit, and an input device. The processor, memory, and input / output interface are connected via a system bus, while the communication interface, display unit, and input device are connected to the system bus via the input / output interface. The processor of the computer device provides computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operating system and computer program stored in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and external devices. The communication interface of the computer device is used to communicate with external terminals via wired or wireless communication, which may be achieved via Wi-Fi, a mobile cellular network, NFC (near field communication), or other technologies. When executed by the processor, the computer program implements a method for determining the linear power density of a fuel assembly. The display unit of the computer device is used to produce a visual display and may be a display screen, a projection device, or a virtual reality imaging device. The display screen can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covering the display screen, or a button, trackball or touchpad set on the computer device casing, or an external keyboard, touchpad or mouse.

[0105] Those skilled in the art will understand that the structures shown in Figures 6 and 7 are merely block diagrams of partial structures related to the solution of the present application, and do not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figures, or combine certain components, or have a different component arrangement.

[0106] In an exemplary embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor implements the steps in the above method embodiments when executing the computer program.

[0107] In an exemplary embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0108] In an exemplary embodiment, a computer program product is provided, including a computer program. When the computer program is executed by a processor, the steps in the above method embodiments are implemented.

[0109] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory may include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processor involved in the various embodiments provided herein may be, but are not limited to, a general-purpose processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic unit, a data processing logic unit based on quantum computing, and the like.

[0110] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0111] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A method for determining the linear power density of a fuel assembly, wherein: The method comprises: Acquire a state signal of a neutron detector of each finger sleeve at a preset height in a first finger sleeve group corresponding to the fuel assembly to be tested; with the fuel assembly to be tested as the center, there are a plurality of finger sleeve groups corresponding to the fuel assembly to be tested, and each of the finger sleeve groups includes a plurality of finger sleeves; When it is determined according to each of the state signals that the neutron detectors at the preset height in each of the finger sleeves in the first finger sleeve group are abnormal, a second finger sleeve group corresponding to the fuel assembly to be tested is determined; the distance between each of the finger sleeves in the second finger sleeve group and the fuel assembly to be tested is greater than the distance between each of the finger sleeves in the first finger sleeve group and the fuel assembly to be tested; At least one effective finger tube is selected from the second finger tube group as a target finger tube; the neutron detector located at the preset height in the effective finger tube is in a normal state; The linear power density of the fuel assembly to be tested is determined based on the data detected by the neutron detector located at the preset height in the target finger sleeve.

2. The method according to claim 1, wherein: The step of determining the linear power density of the fuel assembly to be tested based on the data detected by the neutron detector located at the preset height in the target finger sleeve comprises: For each selected target finger sleeve, based on the data detected by the neutron detector at the preset height in the target finger sleeve, the axial line power determined for the target finger sleeve at the preset height is obtained; Based on the axial linear powers respectively determined by the selected target finger sleeves at the preset heights, the linear power density of the fuel assembly to be tested is determined.

3. The method according to claim 2, wherein: The step of determining the linear power density of the fuel assembly to be tested based on the axial linear power respectively determined at the preset height of each selected target finger sleeve comprises: Determine the weight corresponding to each selected target finger sleeve; Based on the weights corresponding to each selected target finger sleeve, the axial linear powers respectively determined at the preset heights of the selected target finger sleeves are weighted to obtain the linear power density of the fuel assembly to be tested.

4. The method according to claim 3, wherein: The determining of the weight corresponding to each selected target finger sleeve comprises: For each selected target finger sleeve, determine a weight corresponding to the target finger sleeve according to the distance between the target finger sleeve and the fuel assembly to be tested; The distance between the target finger sleeve and the fuel assembly to be tested is negatively correlated with the weight corresponding to the target finger sleeve.

5. The method according to claim 1, wherein: The method further comprises: When it is determined according to each of the state signals that the neutron detector at the preset height in at least one finger tube in the first finger tube group is in a normal state, at least one valid finger tube is selected from the first finger tube group as a standard finger tube; Based on the axial linear power determined by the standard finger sleeve at the preset height, the linear power density of the fuel assembly to be tested is determined.

6. The method according to claim 5, wherein: The step of selecting at least one of the valid finger cannulae from the first finger cannulae group as a standard finger cannulae comprises: In the case that there are a plurality of valid finger cannulas in the first finger cannula group, selecting a first number of the valid finger cannulas from the plurality of valid finger cannulas in the first finger cannula group as the standard finger cannulas; The first number is less than or equal to the second number, the second number is the number of finger sleeves in the closest finger sleeve group corresponding to the fuel assembly to be tested; the distance between each finger sleeve in the closest finger sleeve group and the fuel assembly to be tested is less than the distance between each finger sleeve in other finger sleeve groups corresponding to the fuel assembly to be tested and the fuel assembly to be tested.

7. The method according to claim 1, wherein: The second finger tube group is the valid finger tube group closest to the first finger tube group among the valid finger tube groups around the fuel assembly to be tested, and the valid finger tube group refers to a finger tube group having at least one valid finger tube.

8. A device for determining the linear power density of a fuel assembly, wherein: The device comprises: A signal acquisition module is used to acquire a state signal of a neutron detector of each finger sleeve tube in a first finger sleeve tube group corresponding to the fuel assembly to be tested at a preset height; with the fuel assembly to be tested as the center, there are a plurality of finger sleeve tube groups corresponding to the fuel assembly to be tested, and each of the finger sleeve tube groups includes a plurality of finger sleeve tubes; A first selection module is used to determine a second finger-tube group corresponding to the fuel assembly to be tested when it is determined according to each of the state signals that the neutron detectors at a preset height in each finger-tube group in the first finger-tube group are abnormal; and the distance between each finger-tube in the second finger-tube group and the fuel assembly to be tested is greater than the distance between each finger-tube in the first finger-tube group and the fuel assembly to be tested; A second selection module is used to select at least one valid finger sleeve from the second finger sleeve group as a target finger sleeve; the neutron detector located at the preset height in the valid finger sleeve is in a normal state; The linear power density determination module is used to determine the linear power density of the fuel assembly to be tested based on the data detected by the neutron detector located at the preset height in the target finger sleeve.

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 according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, wherein: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

11. A computer program product comprising a computer program, wherein: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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