Neutron flux density distribution measuring device and system

Abstract

This application discloses a neutron flux density distribution measurement device and system, relating to the field of nuclear industry technology. The device includes: M first optical fibers, each arranged at a corresponding test location in the core of a critical device; each first optical fiber is filled with a neutron-sensitive material; M is a positive integer; a luminescence intensity measurement unit connected to each first optical fiber, used to measure the luminescence intensity of the first optical fiber corresponding to each test location to obtain M luminescence intensities; and a computer connected to the luminescence intensity measurement unit, used to acquire the M luminescence intensities and determine the neutron flux density distribution at each test location based on the M luminescence intensities. According to the embodiments of this application, this device can reduce disturbances to the neutron field within the reactor and can quickly and easily monitor the neutron flux density distribution within the reactor in real time.

Description

Technical Field

[0001] This application belongs to the field of nuclear industry technology, specifically relating to a measuring device and system for neutron flux density distribution. Background Technology

[0002] The critical device is a key means of verifying the physics theory of critical reactors, the calculation model and program of reactor physics, and the nuclear characteristics of new reactor types. The measurement of neutron flux density is the basis of reactor neutronics experiments, and the neutronics parameters in the reactor are generally obtained by measuring the neutron flux density.

[0003] The traditional method for online measurement of neutron flux density distribution is achieved through neutron detectors. A single detector is moved to different measurement locations for individual measurements, or multiple neutron detectors are arranged at multiple measurement locations to directly measure the electrical pulses of the neutron detectors, thereby providing the relative distribution of neutron flux density online. This method has the following drawbacks: (1) The size of the neutron detector is relatively large (several centimeters or even larger), requiring specialized channels. Its placement is greatly limited by the reactor space, and it can only be placed in a few locations. (2) The neutron detector causes significant disturbance to the neutron field within the reactor. The detector and its encapsulated shell, cables, and other materials absorb and scatter neutrons, thereby changing the neutron flux density field to be measured.

[0004] The traditional method for offline measurement of neutron flux density distribution is achieved through an activation plate. A small activation plate is placed at the location to be measured inside the reactor. After irradiation inside the reactor for a certain period of time, the activation plate is removed from the reactor and placed in a high-purity germanium detector. The neutron flux density inside the reactor is calculated by measuring the gamma-ray intensity. This method has the following drawbacks: (1) The activation plate needs to be irradiated inside the reactor for a certain period of time, and it cannot measure the change of neutron flux density over time or provide the neutron flux density in real time. (2) The activation plate has a certain degree of radioactivity after irradiation, and it needs to be disposed of as radioactive waste in accordance with regulations, which increases costs and environmental burden. (3) The measurement process is relatively complicated and the cycle is long.

[0005] In summary, how to reduce disturbances to the neutron field within the reactor and how to quickly and easily monitor the neutron flux density and relative density in real time are research hotspots in this field. Summary of the Invention

[0006] The technical problem to be solved by this application is to provide a neutron flux density distribution measuring device and system to address the above-mentioned shortcomings of the existing technology. Using the neutron flux density distribution measuring device, the disturbance to the neutron field in the reactor can be reduced, and the neutron flux density distribution in the reactor can be monitored quickly and easily in real time.

[0007] In a first aspect, embodiments of this application provide a measuring device for neutron flux density distribution, comprising: M first optical fibers are arranged at the test position of their respective critical device cores; each first optical fiber is filled with neutron-sensitive material; M is a positive integer. The luminous intensity measurement unit is connected to each first optical fiber and is used to measure the luminous intensity of the first optical fiber corresponding to each test position to obtain M luminous intensities. A computer, connected to a luminescence intensity measurement unit, is used to acquire M luminescence intensities and determine the neutron flux density distribution at each measurement location based on the M luminescence intensities.

[0008] In some embodiments of the first aspect, any two first optical fibers have different lengths.

[0009] In some embodiments of the first aspect, the lengths of the M first optical fibers are distributed in an arithmetic progression.

[0010] In some embodiments of the first aspect, each first optical fiber includes a first segment filled with a neutron-sensitive material; The microscopic cross section of the first neutron reaction, the number of atoms per unit volume, the diameter of the first segment, and the shortest length of the first segment are all related to the total number of first optical fibers, the macroscopic cross section of the first neutron reaction, the first volume, and the first perturbation limit. The microscopic cross section of the first neutron reaction is the microscopic cross section of the neutron reaction of the neutron-sensitive material in the first segment. The number of atoms per unit volume is the number of atoms per unit volume of the neutron-sensitive material in the first segment. The macroscopic cross section of the first neutron reaction is the macroscopic cross section of the neutron reaction of the critical device core. The first volume is the volume of the critical device core. The first perturbation limit is the perturbation limit of the first optical fiber on the neutron field inside the reactor.

[0011] In some embodiments of the first aspect, the microscopic cross section of the first neutron reaction, the number of atoms per unit volume, the diameter of the first segment, and the shortest length of the first segment all satisfy formula (1). Formula (1) includes: (1) in, The cross section of the first neutron reaction is shown; N is the number of atoms per unit volume. π is the mathematical constant pi; D is the diameter of the first segment; h is the shortest length of the first segment; The macroscopic cross section of the first neutron reaction; This is the first volume; This is the first disturbance limit.

[0012] In some embodiments of the first aspect, the luminous intensity measuring unit includes: An optical power meter is connected to each of the first optical fibers via an optical switch. The optical switch is used to switch different first optical fibers to the optical power meter. The optical power meter is used to measure the luminous intensity of the first optical fiber switched to itself, so as to measure the luminous intensity of the first optical fiber corresponding to each test position and obtain M luminous intensities.

[0013] In some embodiments of the first aspect, the device further includes: The second optical fiber connects the first optical fiber to an optical switch, and the optical switch connects to an optical power meter via the second optical fiber; the second optical fiber is radiation resistant.

[0014] In some embodiments of the first aspect, the luminous intensity measuring unit includes: M optical power meters are used, each connected to its corresponding first optical fiber, to measure the luminous intensity of the first optical fiber connected to it, so as to measure the luminous intensity of the first optical fiber corresponding to each test position and obtain M luminous intensities.

[0015] In some embodiments of the first aspect, the computer is specifically used for: Substituting the M luminescence intensities into formula (2), the neutron flux density distribution is calculated. Formula (2) includes: (2) in, Let i represent the neutron flux density distribution at the i-th test location, where i is a positive integer greater than or equal to 1 and less than or equal to M; This represents the light emission intensity of the first optical fiber at the i-th test position.

[0016] Based on the same inventive concept, in a second aspect, embodiments of this application also provide a system for measuring neutron flux density distribution, comprising: A critical device, whose core has M locations to be measured; M is a positive integer. The measuring device for neutron flux density distribution of any one of the first aspects is used to determine the neutron flux density distribution at each measurement location.

[0017] According to the neutron flux density distribution measurement device and system provided in the embodiments of this application, a first optical fiber filled with neutron-sensitive material is arranged at the test location in the core of the critical device. Due to the extremely small size of the optical fiber, it can be flexibly arranged in the narrow space within the critical device core, achieving distributed measurement dimensions and centimeter-level spatial resolution. Furthermore, it causes minimal disturbance to the neutron field within the core, thus reducing disturbance to the neutron field. Through the measurement by the luminescence intensity measurement unit, the neutron flux density distribution within the core can be monitored quickly and easily in real time. The luminescence intensity of the first optical fiber corresponding to each test location is measured by the luminescence intensity measurement unit to obtain M luminescence intensities. Then, the computer can determine the neutron flux density distribution at each test location based on the M luminescence intensities, meaning the computer can quickly and easily monitor the neutron flux density distribution within the core in real time.

[0018] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the present application and form part of the specification. They are used together with the embodiments of the present application to explain the application and do not constitute a limitation thereof. The above and other features and advantages will become more apparent to those skilled in the art from the detailed example embodiments described with reference to the accompanying drawings, in which: Figure 1 This diagram illustrates a structural schematic of a neutron flux density distribution measuring device provided in an embodiment of this application. Figure 2 This diagram illustrates a structural schematic of a neutron flux density distribution measuring device provided in an embodiment of this application. Figure 3 The results of the core axial thermal neutron flux density distribution provided in the embodiments of this application are shown. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of this application, exemplary embodiments of this application are described below in conjunction with the accompanying drawings, including various details of the embodiments of this application to aid understanding. These should be considered merely exemplary. Therefore, those skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this application. Similarly, for clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0021] Where there is no conflict, the various embodiments of this application and the features thereof may be combined with each other.

[0022] As used herein, the term “and / or” includes any and all combinations of one or more related enumerated entries.

[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application. As used herein, the singular forms “a” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that when the terms “comprising” and / or “made of” are used in this specification, the presence of the stated feature, integral, step, operation, element, and / or component is specified, but the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof is not excluded. Terms such as “connected” or “linked” are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect.

[0024] Unless otherwise specified, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and this application, and will not be interpreted as having an idealized or overly formal meaning, unless expressly so defined herein.

[0025] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0026] The neutron flux density distribution measurement device provided in this application embodiment can be applied to the determination of neutron parameters within a reactor.

[0027] like Figure 1 As shown, the neutron flux density distribution measurement device provided in this application embodiment may include M first optical fibers, a luminous intensity measurement unit, and a computer.

[0028] M first optical fibers are arranged at the test positions of their respective critical device cores; each first optical fiber is filled with neutron-sensitive material; M is a positive integer.

[0029] In other words, the core of the critical device has M test locations, and each test location has a corresponding first optical fiber.

[0030] For example, each of the first optical fibers is filled with neutron-sensitive material. After the neutron-sensitive material reacts with neutrons, it will generate γ-rays of a specific wavelength. By measuring the luminescence intensity in each of the first optical fibers, the neutron flux density distribution in the reactor can be obtained in real time.

[0031] For example, each of the first optical fibers has the same material composition.

[0032] In this embodiment of the application, a first optical fiber filled with neutron-sensitive material is arranged at the test location in the core of the critical device. Since the optical fiber is extremely small, it can be flexibly arranged in the narrow space inside the critical device core to achieve distributed measurement dimensions and achieve spatial resolution at the centimeter level. Moreover, it causes very little disturbance to the neutron field inside the core, that is, it can reduce the disturbance to the neutron field inside the core.

[0033] It should be noted that the value of M can be set according to the actual situation, and is not limited here.

[0034] The luminous intensity measurement unit is connected to each first optical fiber and is used to measure the luminous intensity of the first optical fiber corresponding to each test position to obtain M luminous intensities.

[0035] Understandably, each test location is equipped with a first optical fiber. The neutron-sensitive material in each first optical fiber reacts with neutrons to produce γ-rays of a specific wavelength. The luminescence intensity measurement unit can measure the luminescence intensity corresponding to each first optical fiber, obtain M luminescence intensities, and send the M luminescence intensities to the computer.

[0036] A computer, connected to a luminescence intensity measurement unit, is used to acquire M luminescence intensities and determine the neutron flux density distribution at each measurement location based on the M luminescence intensities.

[0037] In this embodiment, the neutron flux density distribution within the reactor can be monitored quickly and easily in real time by measuring the luminescence intensity measurement unit. The luminescence intensity of the first optical fiber corresponding to each test location is measured by the luminescence intensity measurement unit to obtain M luminescence intensities. The computer can then determine the neutron flux density distribution at each test location based on the M luminescence intensities, meaning the computer can monitor the neutron flux density distribution within the reactor quickly and easily in real time.

[0038] In some implementations, any two first optical fibers are of different lengths. That is, all first optical fibers are of different lengths.

[0039] In some examples, the lengths of the M first optical fibers are distributed in an arithmetic progression.

[0040] For example, the length of the first optical fiber is 1h, the length of the second optical fiber is 2h, the length of the third optical fiber is 3h, and so on, with the length of the Mth optical fiber being M×h.

[0041] In some embodiments, each first optical fiber includes a first segment filled with a neutron-sensitive material; The microscopic cross section of the first neutron reaction, the number of atoms per unit volume, the diameter of the first segment, and the shortest length of the first segment are all related to the total number of first optical fibers, the macroscopic cross section of the first neutron reaction, the first volume, and the first perturbation limit. The microscopic cross section of the first neutron reaction is the microscopic cross section of the neutron reaction of the neutron-sensitive material in the first segment. The number of atoms per unit volume is the number of atoms per unit volume of the neutron-sensitive material in the first segment. The macroscopic cross section of the first neutron reaction is the macroscopic cross section of the neutron reaction of the critical device core. The first volume is the volume of the critical device core. The first perturbation limit is the perturbation limit of the first optical fiber on the neutron field inside the reactor.

[0042] For example, the microscopic cross section of the first neutron reaction represents the probability of a nuclear reaction between one neutron and one target nucleus.

[0043] For example, the macroscopic cross section of the first neutron reaction represents the average probability of a nuclear reaction between one neutron and all atomic nuclei within a unit volume. For instance, if the reactor core is entirely composed of graphite, the macroscopic cross section of the neutron reaction in graphite is 0.385 cm⁻¹. -1 .

[0044] For example, the first disturbance limit is 10. -5 .

[0045] Taking the length of the first optical fiber as 1h, the second as 2h, the third as 3h, and so on, with the length of the Mth optical fiber being M×h as an example, then...

[0046] In some examples, the microscopic cross section of the first neutron reaction, the number of atoms in the first unit volume, the diameter of the first segment, and the shortest length of the first segment all satisfy formula (1). Formula (1) includes: (1) in, The cross section of the first neutron reaction is shown; N is the number of atoms per unit volume. π is the mathematical constant pi; D is the diameter of the first segment; h is the shortest length of the first segment; The macroscopic cross section of the first neutron reaction; This is the first volume; This is the first disturbance limit.

[0047] In this example, by using the above formula (1) to select the first optical fiber that meets the conditions, the disturbance of the first optical fiber to the neutron field in the reactor can be minimized.

[0048] For example, δ N represents the average probability of a nuclear reaction between one neutron and a unit volume of neutron-sensitive material within an optical fiber.

[0049] It should be noted that the purpose of the experiment is to measure the relative distribution of neutron flux density within the reactor (i.e., the neutron field within the reactor). As a neutral particle, neutrons can generally only be measured through nuclear reactions between neutrons and detector materials (i.e., neutron-sensitive materials). For example, boron neutron proportional counter tube detectors utilize the nuclear reaction between B10 and neutrons. However, after a neutron undergoes a nuclear reaction, it inevitably disturbs the neutron field within the reactor, meaning that the measured neutron field is not the original neutron field.

[0050] Compared to neutron detectors, which require specialized channels and have detector sizes on the order of several centimeters, optical fibers can have diameters on the order of hundreds of micrometers and do not require specialized large channels, thus causing relatively little disturbance to the neutron field within the reactor. However, the content of neutron-sensitive material within the optical fiber, as well as the size and quantity of the fiber, can also generate significant disturbances if they are excessive. Therefore, formula (1) quantitatively limits the disturbance of the neutron field by the optical fiber.

[0051] In some implementations, such as Figure 2 As shown, the luminous intensity measurement unit includes: An optical power meter is connected to each of the first optical fibers via an optical switch. The optical switch is used to switch different first optical fibers to the optical power meter. The optical power meter is used to measure the luminous intensity of the first optical fiber switched to itself, so as to measure the luminous intensity of the first optical fiber corresponding to each test position and obtain M luminous intensities.

[0052] In this embodiment, by setting an optical switch, the number of optical power meters can be reduced, thereby reducing the cost of the luminous intensity measurement unit.

[0053] In some embodiments, the device further includes: The second optical fiber connects the first optical fiber to an optical switch, and the optical switch connects to an optical power meter via the second optical fiber; the second optical fiber is radiation resistant.

[0054] In other words, the second optical fiber is a radiation-resistant optical fiber.

[0055] In other embodiments, the luminous intensity measuring unit includes: M optical power meters are used, each connected to its corresponding first optical fiber, to measure the luminous intensity of the first optical fiber connected to it, so as to measure the luminous intensity of the first optical fiber corresponding to each test position and obtain M luminous intensities.

[0056] In other words, an optical power meter is connected to a first optical fiber, so that the luminous intensity of multiple first optical fibers can be measured simultaneously, which can improve the measurement efficiency of the luminous intensity of the first optical fiber.

[0057] In some implementations, the computer is specifically used for: Substituting the M luminescence intensities into formula (2), the neutron flux density distribution is calculated. Formula (2) includes: (2) in, Let i represent the neutron flux density distribution at the i-th test location, where i is a positive integer greater than or equal to 1 and less than or equal to M; This represents the light emission intensity of the first optical fiber at the i-th test position.

[0058] In this embodiment, the neutron flux density distribution can be determined quickly and accurately using the above formula (2), thereby enabling rapid and convenient real-time monitoring of the neutron flux density distribution within the reactor.

[0059] The principle behind the above formula (2) is explained below.

[0060] According to the principle of fiber optic light emission, neutrons undergo a nuclear reaction with the neutron-sensitive material inside the optical fiber, releasing energy to excite light emission. Therefore, the intensity of the light emission... Reaction rate with neutron nuclei R i It is directly proportional to the number of nuclear reactions per unit time.

[0061] The nuclear reaction rate R i =δ·N·V· Where δ·N is the probability of a nuclear reaction between the neutron-sensitive material in the optical fiber and one neutron, and V is the volume of the optical fiber's sensitive material. Since the material composition of each segment of the optical fiber is the same and their lengths are of equal difference, R... i Relative distribution with neutron flux density Proportional.

[0062] Therefore, luminous intensity Relative distribution with neutron flux density Proportional. Luminous intensity The relative distribution is the neutron flux density distribution. The relative distribution of .

[0063] Based on the same inventive concept, this application also relates to a method for measuring neutron flux density distribution, which can be applied to the neutron flux density distribution measuring device described in the above embodiments.

[0064] The method may include: The luminous intensity of the first optical fiber at each test position is measured by the luminous intensity measurement unit to obtain M luminous intensities; M emission intensities are obtained by computer, and the neutron flux density distribution at each test location is determined based on the M emission intensities.

[0065] The neutron flux density distribution measurement method provided in this application has the beneficial effects and implementation methods of the neutron flux density distribution measurement device provided in this application. For details, please refer to the specific description of the neutron flux density distribution measurement device in the above embodiments. This embodiment will not repeat the description here.

[0066] To better understand the neutron flux density distribution measurement device and method provided in the embodiments of this application, the following description is provided in conjunction with specific implementation methods.

[0067] like Figure 2 As shown, optical fibers of the same material composition and of equal length (i.e., the first optical fiber) are arranged simultaneously at the test location in the core of the critical device. The optical fibers are filled with neutron-sensitive material (i.e., optical fibers containing neutron-sensitive material, i.e., the first optical fiber). The neutron-sensitive material will generate γ-rays of a specific wavelength after reacting with neutrons. By measuring the luminescence intensity in each optical fiber, the relative distribution of neutron flux density in the reactor can be obtained in real time.

[0068] In this embodiment, the critical device core is composed of graphite block assemblies. The graphite blocks contain channels for loading fuel rods, and the core can be loaded with different numbers of fuel rods depending on experimental requirements. The neutron-sensitive materials are gadolinium (Gd) and terbium (Tb), meaning that Gd and Tb elements are doped into the glass fiber material in a ratio equal to natural nuclides. Gd reacts with neutrons within the reactor core, and the energy released from this reaction is deposited in the glass fiber matrix, causing Tb to be in an excited state. When Tb de-excites, it emits green light with a wavelength of approximately 540 nm.

[0069] Optical fiber consists of two segments: one containing a neutron-sensitive material and the other not containing a neutron-sensitive material. The optical fiber containing the neutron-sensitive material satisfies formula (1): (1) In formula (1), The thermal neutron cross-section of Gd, a neutron-sensitive material within an optical fiber, is 49000b (1b = 10⁻⁶). -24 cm 2 ); N represents the number of atoms per unit volume of the neutron-sensitive material within the optical fiber; the atomic number density of Gd is 1 × 10⁻⁶. 20 pcs / cm 3 ; Pi; D is the diameter of the neutron-sensitive material fiber segment (i.e., the first segment), which is 500 μm in diameter; h is the length of the shortest neutron-sensitive material fiber segment, which is 10cm. That is, the fiber lengths are 10cm, 20cm, ..., 150cm. M represents the number of fiber segments of the neutron-sensitive material, with 15 fiber segments arranged axially at one radial point. The image shows the macroscopic cross-section of the neutron reaction in the reactor core. The core is entirely composed of graphite, and the macroscopic cross-section of the neutron reaction in graphite is 0.385 cm. -1 ; The volume of the reactor core is 175cm in diameter and 150cm in length. The reactor core is a hexagonal prism with a radial distance between opposite sides of 175cm and an axial length of 150cm. To limit the disturbance of the neutron field within the reactor by the optical fiber, this embodiment uses 10. -5 .

[0070] Calculations show that the above fiber optic arrangement has an impact of only 7.5 × 10⁻⁶ on the in-reactor neutron field. -6 It is below the limit.

[0071] The neutron flux density distribution factor at each measurement location is obtained from formula (2): (2) In formula (2), is the normalized relative distribution factor of neutron flux density at the i-th test location; The luminous intensity at the i-th test location is obtained by the difference between the luminous intensity in the i-th fiber segment and the luminous intensity in the (i-1)-th fiber segment. M represents the number of fiber segments in the neutron-sensitive material, which, as mentioned above, is 15 segments.

[0072] Figure 3 It is the result of the relative distribution of axial thermal neutron flux density in the reactor core. Figure 3 The horizontal axis represents the axial axis, with units of centimeters (cm); the vertical axis represents the normalized neutron flux density factor (neutron flux density distribution). A core model is constructed using the general Monte Carlo program RMC. The theoretical value of the thermal neutron flux density distribution can be calculated using the neutron flux counter in the RMC program. The material, dimensions, and arrangement of the optical fiber are modeled in detail using the RMC program. The luminous intensity within the fiber can be obtained by statistically analyzing the (n, γ) reactivity. Combined with formula (2), the measured value of the thermal neutron flux density distribution is obtained. Figure 3 It can be seen that the measured value of the thermal neutron flux density distribution is in good agreement with the theoretical value, with a relative deviation within ±5%.

[0073] Furthermore, in the online measurement method for neutron flux density distribution in the critical device described above, the measurement system includes an optical fiber containing a neutron-sensitive material, a radiation-resistant optical fiber without a neutron-sensitive material, an optical switch, an optical power meter, and a computer. The optical switch can switch different optical fibers to the optical power meter, the optical power meter can measure the luminous intensity within the optical fiber, and the computer can process the luminous intensity data.

[0074] The beneficial effects of this application's embodiments are: the optical fiber is extremely small in size, allowing for flexible arrangement within the narrow space of the reactor core, enabling distributed measurement dimensions and achieving centimeter-level spatial resolution, while minimizing disturbance to the neutron field within the reactor core. Through the transmission of optical signals from radiation-resistant optical fibers and the measurement by an optical power meter, the neutron flux density distribution within the reactor core can be monitored quickly and easily in real time.

[0075] It is understood that the various method embodiments mentioned above in this application can be combined with each other to form combined embodiments without violating the principle and logic. Due to space limitations, this application will not elaborate further. Those skilled in the art will understand that in the above methods of specific implementation, the specific execution order of each step should be determined by its function and possible internal logic.

[0076] Based on the same inventive concept, embodiments of this application also provide a measurement system for neutron flux density distribution, comprising: A critical device, whose core has M locations to be measured; M is a positive integer. The neutron flux density distribution measuring device in the above embodiment is used to determine the neutron flux density distribution at each measurement location.

[0077] The neutron flux density distribution measurement system provided in this application includes the neutron flux density distribution measurement device of the above embodiments, that is, it has the beneficial effects and implementation methods of the neutron flux density distribution measurement device provided in this application. For details, please refer to the specific description of the neutron flux density distribution measurement device in the above embodiments. This embodiment will not repeat the description here.

[0078] Those skilled in the art will understand that all or some of the steps, systems, and apparatuses disclosed above, and their functional modules / units, can be implemented as software, firmware, hardware, or suitable combinations thereof. In hardware implementations, the division between functional modules / units mentioned above does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed collaboratively by several physical components. Some or all physical components may be implemented as software executed by a computer, such as a central computer, digital signal processing computer, or microcomputer, or as hardware, or as integrated circuits, such as application-specific integrated circuits (ASICs). Such software can be distributed on a computer-readable storage medium, which may include computer storage media (or non-transitory media) and communication media (or transient media).

[0079] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of an instruction containing one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0080] Example embodiments have been disclosed herein, and while specific terminology has been used, it is for general illustrative purposes only and should not be construed as limiting. In some instances, it will be apparent to those skilled in the art that features, characteristics, and / or elements described in conjunction with particular embodiments may be used alone, or in combination with features, characteristics, and / or elements described in conjunction with other embodiments, unless otherwise expressly indicated. Therefore, those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of this application as set forth by the appended claims.

Claims

1. A measuring device for neutron flux density distribution, characterized in that, include: M first optical fibers, each of which is arranged at the test position of its corresponding critical device core. Each of the first optical fibers is filled with a neutron-sensitive material; M is a positive integer; A luminous intensity measurement unit is connected to each of the first optical fibers and is used to measure the luminous intensity of the first optical fiber corresponding to each of the test positions to obtain M luminous intensities. A computer, connected to the luminescence intensity measurement unit, is used to acquire M luminescence intensities and determine the neutron flux density distribution at each of the measured locations based on the M luminescence intensities.

2. The apparatus according to claim 1, characterized in that, The lengths of any two of the first optical fibers are different.

3. The apparatus according to claim 2, characterized in that, The lengths of the M first optical fibers are distributed in an arithmetic progression.

4. The apparatus according to claim 3, characterized in that, Each of the first optical fibers includes a first segment, which is filled with a neutron-sensitive material; The microscopic cross section of the first neutron reaction, the number of atoms per unit volume, the diameter of the first segment, and the shortest length of the first segment are all related to the total number of the first optical fibers, the macroscopic cross section of the first neutron reaction, the first volume, and the first disturbance limit. The microscopic cross section of the first neutron reaction is the microscopic cross section of the neutron-sensitive material within the first segment. The number of atoms per unit volume is the number of atoms per unit volume of the neutron-sensitive material within the first segment. The macroscopic cross section of the first neutron reaction is the macroscopic cross section of the neutron reaction in the core of the critical device. The first volume is the volume of the core of the critical device. The first disturbance limit is the disturbance limit of the first optical fiber to the neutron field within the reactor.

5. The apparatus according to claim 4, characterized in that, The microscopic cross section of the first neutron reaction, the number of atoms in the first unit volume, the diameter of the first segment, and the shortest length of the first segment all satisfy formula (1). Formula (1) includes: （1） in, The microscopic cross-section of the first neutron reaction; N is the number of atoms per unit volume in the first neutron reaction; π is the mathematical constant pi; D is the diameter of the first segment; h is the shortest length of the first segment; This is the macroscopic cross section of the first neutron reaction; This refers to the first volume; This is the first disturbance limit.

6. The apparatus according to claim 1, characterized in that, The luminous intensity measurement unit includes: An optical power meter is connected to each of the first optical fibers via an optical switch; the optical switch is used to switch different first optical fibers to the optical power meter; the optical power meter is used to measure the luminous intensity of the first optical fiber switched to itself, so as to measure the luminous intensity of the first optical fiber corresponding to each of the test positions, so as to obtain M luminous intensities.

7. The apparatus according to claim 6, characterized in that, The device further includes: The second optical fiber connects the first optical fiber to the optical switch, and the optical switch connects to the optical power meter via the second optical fiber; the second optical fiber is radiation resistant.

8. The apparatus according to claim 2, characterized in that, The luminous intensity measurement unit includes: M optical power meters are used, each of which is connected to its corresponding first optical fiber to measure the luminous intensity of the first optical fiber connected to it, so as to measure the luminous intensity of the first optical fiber corresponding to each of the test positions and obtain M luminous intensities.

9. The apparatus according to claim 1, characterized in that, The computer is specifically used for: Substituting the M luminescence intensities into formula (2), the neutron flux density distribution is calculated; Formula (2) includes: （2） in, The neutron flux density distribution at the i-th measured location is represented by , where i is a positive integer greater than or equal to 1 and less than or equal to M; The intensity of light emitted by the first optical fiber at the i-th position to be measured is represented.

10. A measurement system for neutron flux density distribution, characterized in that, include: A critical device, whose core has M locations to be measured; M is a positive integer. The measuring device for neutron flux density distribution according to any one of claims 1 to 9 is used to determine the neutron flux density distribution at each of the said locations to be measured.

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