Fast neutron multiple measurement device with active and passive measurement functions

Abstract

The invention relates to the field of nuclear material attribute nondestructive measurement and verification authentication, in particular to a fast neutron multiple measurement device with active and passive measurement functions. The invention discloses a fast neutron multiple measurement device with active and passive measurement functions. The fast neutron multiple measurement device comprises a fast neutron detector, a sample container, a neutron generator and a neutron source shielding cone, the fast neutron detector is of an annular array structure; the sample container is arranged in a central measurement area; the neutron generator is arranged at the end part of the annular array; the neutron generator has an alpha timing function; the neutron source shielding cone is arranged between the neutron generator and the fast neutron detector. According to the multiple measurement device for the fast neutrons, the multiple active measurement function and the multiple passive measurement function of the fast neutrons can be achieved under the condition that existing components of the device are not changed.

Description

Technical Field

[0001] The present application relates to the field of non-destructive measurement and verification and certification of nuclear material properties, and specifically to a fast neutron multiplicity measurement device with active and passive measurement functions. Background Art

[0002] The fast neutron multiplicity measurement device is generally composed of a plurality of fast neutron detectors (such as liquid scintillation detectors) with neutron gamma discrimination arranged in a ring or sphere to form a detector array. The measurement device can measure the multiplicity of fast neutrons released by the nuclear material sample at the center of the array. Based on the fast neutron multiplicity measurement data, the quality attributes of the measured nuclear material can be further analyzed.

[0003] From the perspective of measurement methods, there are active and passive methods. The active method requires an external neutron source (such as an Am-Li neutron source) to inject into the nuclear material sample and induce fission of the nuclear material. The measuring device performs multiplicity measurement on the neutrons induced by the external source, and mainly measures uranium materials. The passive method directly measures the multiplicity of spontaneous fission neutrons of nuclear materials, and mainly measures plutonium materials.

[0004] Corresponding to fast neutrons, there is also a thermal neutron multiplicity measurement device. Its notable feature is that it uses moderation materials such as polyethylene to slow down the neutrons leaked from nuclear materials, and arranges He-3 and other similar thermal neutron detectors in the moderation materials to measure the multiplicity of the slowed thermal neutrons.

[0005] The existing active fast neutron multiplicity measurement device is based on the Am-Li neutron source. Due to the deep penetration characteristics of the neutron source, it is impossible to effectively shield it in the limited space of the fast neutron multiplicity measurement device. The interference of the Am-Li neutron source cannot be directly used for passive measurement, so when performing passive measurement, the Am-Li neutron source needs to be removed. Summary of the invention

[0006] The purpose of the present application is to provide a fast neutron multiplicity measurement device with active and passive measurement functions, so as to achieve both active and passive measurement functions without increasing or reducing the components of the measurement device.

[0007] To solve the above problems, the present application provides a fast neutron multiplicity measurement device with active and passive measurement functions, including a fast neutron detector, a sample container, a neutron generator, and a neutron source shielding cone;

[0008] The fast neutron detector is in a ring array structure; the sample container is arranged in the central measurement area;

[0009] The neutron generator is arranged at the end of the annular array; the neutron generator has an alpha timing function;

[0010] The neutron source shielding cone is arranged between the neutron generator and the fast neutron detector.

[0011] In some embodiments, the annular array structure of the fast neutron detectors is a single-ring arrangement or a multi-ring arrangement, and each ring is composed of a plurality of detectors evenly arranged.

[0012] In some embodiments, the specific number of rings of the annular array structure of the fast neutron detectors and the number of the detectors in each ring are determined by the total neutron detection efficiency.

[0013] In some embodiments, the inner diameter of the annular array structure of the fast neutron detector is determined by the maximum outer diameter of the sample to be detected.

[0014] In some embodiments, the neutron generator is a neutron generator for DD reaction, or a neutron generator for DT reaction, and has an alpha timing function.

[0015] In some embodiments, the neutron generator is disposed at one end of the annular array.

[0016] In some embodiments, the target point of the neutron generator is located at the central axis of the annular array.

[0017] In some embodiments, the distance between the target point and the center of the detector array is determined by the following equation: h = d / arctg(θ1) / 2;

[0018] Among them, h is the distance between the target and the center of the detector array; θ1 is the angle of the neutron emission area associated with time and space; d is the maximum outer diameter of the sample under test.

[0019] The beneficial effects of the present application are as follows: the fast neutron multiplicity measurement device with active and passive measurement functions of the present application can simultaneously realize the functions of active measurement and passive measurement of fast neutron multiplicity without changing the existing components of the device, thereby avoiding additional structural adjustments, simplifying the operation of the equipment, improving the flexibility and efficiency of the measurement, and reducing the complexity and cost of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is an overall schematic diagram of the fast neutron multiplicity measurement device of the present application;

[0021] Figure 2 This is a schematic diagram of the layout of the various components of the fast neutron multiplicity measurement device of the present application. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0024] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so that once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0025] In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0026] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0027] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of this application.

[0028] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0029] In order to realize both active and passive measurement functions without increasing or decreasing the number of components of the measurement device, the present application provides a fast neutron multiplicity measurement device with active and passive measurement functions, such as Figure 1-Figure 2 shown.

[0030] A fast neutron multiplicity measurement device of the present application comprises a fast neutron detector 1, a sample container 2, a neutron generator 3 and a neutron source shielding cone 4.

[0031] The fast neutron detector 1 is in a ring array structure. The sample container 2 is arranged in the central measurement area.

[0032] The neutron generator 3 is arranged at the end of the annular array and has an alpha timing function.

[0033] The neutron source shielding cone 4 is arranged between the neutron generator 3 and the fast neutron detector 1 .

[0034] The neutron generator 3 with α timing function is integrated into the passive fast neutron multiplicity measurement device, realizing active and passive dual-mode measurement capabilities. The two measurement modes have no physical interference with each other and do not require any mechanical structure layout adjustment.

[0035] In active measurement, the neutron generator is started to emit neutrons according to the set parameters, and the α timing signal is used as the opening coincidence signal. Only the neutron signal measured by the fast neutron detector within the coincidence window is measured for coincidence and fast neutron multiplicity, which greatly suppresses the measurement interference of non-correlated neutrons of neutron generator 3 and scattered reflected neutrons in the environment. In passive measurement, the neutron generator does not work, and only the neutron signal measured by the fast neutron detector needs to be measured for self-coincidence and fast neutron multiplicity.

[0036] The neutron generator 3 with α timing function can be arranged at one end of the axis of the annular detector; or the α timing neutron generator 3 can be arranged at both ends of the axis of the annular detector to achieve spatial uniformity of active neutron source irradiation on the measurement sample and improve the accuracy of quality attribute measurement of uranium materials.

[0037] The fast neutron multiplicity measurement device of this application has both active and passive measurement functions without increasing or decreasing the components of the measurement device. It can measure samples containing plutonium materials, samples containing uranium materials, and samples containing a mixture of uranium and plutonium materials. It solves the problem of interference of the Am-Li neutron source on the detector during passive measurement, improves the integration of the fast neutron multiplicity measurement device and user convenience, and broadens the measurement application scenarios of the fast neutron multiplicity measurement device.

[0038] A neutron generator 3 is used as a driving source. The neutron generator can be a neutron generator 3 for a DD reaction or a neutron generator 3 for a DT reaction, replacing a conventional Am-Li neutron source. When performing passive measurement, the neutron generator 3 does not work, that is, does not generate neutrons. When performing active measurement, the neutron generator 3 works according to the set parameter conditions to generate neutrons as a driving source.

[0039] Since the neutron source 5 generated by the neutron generator 3 emits in the direction of 4π, in order to reduce the interference of invalid neutrons generated by the neutron generator 3 (referring to the neutrons emitted by the neutron generator that cannot directly irradiate the sample under test) on the fast neutron multiplicity detector, a neutron source shielding cone 4 is arranged between the target point 31 of the neutron generator 3 and the detector to shield the neutrons directly emitted by the neutron generator 3 to the detector, thereby reducing the background signal intensity of the fast neutron multiplicity detector.

[0040] The neutron generator 3 uses a neutron generator with an α timing function. The α timing detector marks the neutrons that are correlated in space and time and gives a high-precision timing signal. Only the neutrons that are correlated in time and space are emitted through the central through hole of the neutron source shielding cone 4 to the nuclear material detection area of ​​the fast neutron multiplicity detector array as an active neutron source 5.

[0041] Specifically, the structural layout of the fast neutron multiplicity measurement device of the present application with active and passive measurement functions is as follows: Figure 1 As shown. It consists of an annular array of fast neutron detectors 1, a sample container 2 in the central measurement area, a neutron generator 3 with an α timing function, and a neutron source shielding cone 4 with a central through hole. It also includes a bracket structure of the fast neutron detector 1 and a bracket structure of the sample container 2. The fast neutron multiplicity measurement device adopts a detector array arranged in a cylindrical ring shape, wherein the cylindrical ring shape can be a single ring or multiple rings. The two axial ends of the annular array are left empty, and a neutron generator 3 is arranged at one end. A neutron source shielding cone 4 with a through hole in the center is arranged between the neutron generator 3 and the fast neutron detector 1 array to shield the neutrons directly shot by the neutron generator 3 to the fast neutron detector 1.

[0042] The positional relationship between the fast neutron detector 1, the target point 31 and direction of the neutron generator 3, and the neutron source shield 4 is as follows: Figure 2 shown.

[0043] The annular array of fast neutron detectors 1 can be arranged in a single ring or multiple rings, and each ring is composed of multiple detectors evenly arranged. The specific number of rings and the number of detectors in each ring are determined by the total neutron detection efficiency. The inner cavity diameter size D of the annular fast neutron detector 1 is determined by the maximum outer diameter d of the sample to be tested. The axial ends of the annular array are left empty for arranging the neutron generator 3 with α timing function, which can be arranged at only one end or at both ends.

[0044] The target point 31 of the neutron generator 3 is arranged on the annular central axis, and the distance h from the center of the detector array is determined by the neutron emission area angle θ1 associated with time and space and the maximum outer diameter d of the sample to be tested. The formula is as follows:

[0045] h=d / arctg(θ1) / 2

[0046] The neutron source shielding body 4 is arranged between the neutron generator 3 and the detector array. The axial projection area angle θ2 of the neutron source shielding cone 4 effectively covers the detectors of the detector array, preventing the non-correlated neutrons of the neutron generator 3 from causing strong background interference to the detectors. There is a conical through hole in the center for the spatial and temporal correlated neutrons of the neutron generator 3 to directly irradiate the sample area under test, and the angle of the conical through hole is slightly larger than the angle θ1 of the correlated neutron emission area.

[0047] The workflow of the measuring device using different methods is as follows:

[0048] (1) Passive fast neutron multiplicity measurement process: For example, when the measurement object is plutonium material, the neutron generator 3 is not working. At this time, the fast neutron multiplicity measurement device with active and passive measurement functions of the present application can realize passive fast neutron multiplicity measurement.

[0049] The S1 multi-channel fast signal acquisition and analysis equipment measures the pulse signals of all detectors in the fast neutron detector 1 array, calculates and analyzes the characteristic information of the pulse signals, and distinguishes the neutron gamma signals.

[0050] S2 performs multiplicity measurement and analysis on all neutron signals to obtain neutron multiplicity results.

[0051] S3 obtains the quality attributes of the material of the object being measured according to the set parameters and algorithms.

[0052] (2) Active fast neutron multiplicity measurement process: For example, when the measurement object is uranium material, the neutron generator 3 works according to the set parameters. At this time, the fast neutron multiplicity measurement device of the present application can realize active fast neutron multiplicity measurement.

[0053] The S1 multi-channel fast signal acquisition and analysis equipment measures the pulse signals of all detectors in the fast neutron detector 1 array and the α detector pulse signals of the neutron generator 3, calculates and analyzes the characteristic information of the detector pulse signals and distinguishes the neutron gamma signals, and calculates and analyzes the characteristic information of the α detector pulse signals to obtain effective α timing signals.

[0054] S2 uses the α timing signal as the gate signal to perform multiplicity measurement and analysis on the neutron signal in the coincidence window after the timing signal to obtain the neutron multiplicity result.

[0055] S3 obtains the mass properties of the uranium material of the object to be measured according to the set parameters and algorithms.

[0056] (3) Active and passive fast neutron multiplicity measurement process: For example, when the measurement object is a uranium-plutonium mixed material, the active method and the passive method can be used successively to perform composite fast neutron multiplicity measurement.

[0057] S1 performs the passive fast neutron multiplicity measurement process for measurement.

[0058] S2 performs the active fast neutron multiplicity measurement process for measurement.

[0059] S3 obtains the mass properties of the measured objects, plutonium and uranium, based on the results of the combined measurement of the passive method and the active method, according to the set parameters and algorithms.

Claims

1. A fast neutron multiplicity measurement device, characterized in that: It includes fast neutron detector, sample container, neutron generator and neutron source shielding cone; The fast neutron detector is in a ring array structure; the sample container is arranged in the central measurement area; The neutron generator is arranged at the end of the annular array; the neutron generator has an alpha timing function; and the neutron source shielding cone is arranged between the neutron generator and the fast neutron detector.

2. The fast neutron multiplicity measurement device according to claim 1, characterized in that: The annular array structure of the fast neutron detector is a single-ring arrangement or a multi-ring arrangement, and each ring is composed of a plurality of detectors evenly arranged.

3. The fast neutron multiplicity measuring device according to claim 2, characterized in that: The specific number of rings of the annular array structure of the fast neutron detectors and the number of the detectors in each ring are determined by the total neutron detection efficiency.

4. The fast neutron multiplicity measurement device according to claim 1, characterized in that: The inner cavity diameter of the annular array structure of the fast neutron detector is determined by the maximum outer diameter of the sample to be tested.

5. The fast neutron multiplicity measurement device according to claim 1, characterized in that: The neutron generator is a DD reaction neutron generator or a DT reaction neutron generator and has an alpha timing function.

6. The fast neutron multiplicity measurement device according to claim 1, characterized in that: The neutron generator is arranged at one end of the annular array.

7. The fast neutron multiplicity measurement device according to claim 1, characterized in that: The target point of the neutron generator is arranged on the central axis of the annular array.

8. The fast neutron multiplicity measurement device according to claim 7, characterized in that: The distance between the target point and the center of the detector array is determined by the following equation: h = d / arctg(θ1) / 2; Among them, h is the distance between the target and the center of the detector array; θ1 is the angle of the neutron emission area associated with time and space; d is the maximum outer diameter of the sample under test.

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