Method and system for measuring subcritical degree of reactor core based on neutron generator

Abstract

The invention discloses a method and system for measuring the subcritical degree of a reactor core based on a neutron generator, and the method comprises the steps: generating neutrons through the neutron generator after the installation and joint debugging of the neutron generator and a neutron detector in the reactor core, and maintaining the stability of the reactor core; and after the reactor core is stabilized for a preset time, cutting off the neutron generator and measuring to obtain the subcritical degree of the reactor core. The neutron generator is adopted to replace a radioactive neutron source in a traditional source hopping method, inherent risks existing in the processes of radioactive neutron source management, use, storage and the like can be eliminated, for example, adverse effects of high radioactivity on related personnel can be eliminated, and the safety of system operation is improved; meanwhile, after the neutron generator is powered off, the neutron generator can serve as conventional equipment, the neutron generator has the advantages of generating single-energy neutrons, being controllable in neutron yield, movable, reusable and the like, the equipment cost can be greatly reduced, high economic value is provided for reactor core measurement, and technical support and technical reference are provided for promoting reactor core measurement technology research.

Description

Technical Field

[0001] The present application relates to the technical field of core performance measurement, and specifically to a core subcriticality measurement method and system based on a neutron generator, which utilizes a neutron generator to replace a traditional radioactive neutron source used in measuring core subcriticality by a source jump method, thereby realizing core subcriticality measurement. By measuring the difference between the core subcriticality when a control rod to be tested is at the top and the core subcriticality when the control rod to be tested is at the bottom, the integral value of the control rod to be tested can be obtained. Background Art

[0002] The subcritical reactor operates in a stable state under the action of an external neutron source. If the external neutron source is removed instantaneously, the neutron flux density in the subcritical reactor decays according to the characteristics of the subcritical reactor. The subcriticality of the reactor is obtained by measuring the neutron counts in the two operating states. Therefore, two neutron dynamic equations are used to describe the two operating states of the subcritical reactor. The first is the neutron dynamic equation under the action of an external neutron source, and the second is the neutron dynamic equation without the action of an external neutron source.

[0003] (1) Neutron dynamic equations for a subcritical reactor operating in a steady state driven by an external neutron source

[0004]

[0005] Where t is time, N(t) is the neutron density at time t, ρ is the reactivity, β is the delayed neutron fraction, Λ is the neutron generation time, and λ is the i is the delayed neutron decay constant, C i is the concentration of delayed neutron precursor nuclei in group i, and S(t) is the external source intensity.

[0006] A subcritical core, under the action of a constant external neutron source S(t) = S0, if it is in equilibrium (steady state), all time derivatives are equal to zero. From the second equation of formula (1): have:

[0007]

[0008] Substituting into the first equation of formula (1), we have:

[0009]

[0010] Since the subcritical core is in equilibrium, that is, N = N0 is constant, and ρ and S are equal to constants ρ0 and S0, then:

[0011]

[0012] The concentration of delayed neutron precursor nuclei is:

[0013]

[0014] (2) Reactor neutron dynamic equations without external neutron source

[0015] The external neutron source is instantly jumped out of the core. The reactivity (subcriticality) does not change before and after the source jump. When there is no external neutron source:

[0016]

[0017] The second equation of equation (4) i C i (t) Substituting the sum into the first formula gives:

[0018]

[0019] Integrating both sides of equation (5), we have:

[0020]

[0021] At t = 0, the external neutron source is suddenly removed, and the initial condition of equation (6) is:

[0022] When t = 0, N(0) = N0, ρ=ρ0

[0023] Since the core is subcritical, after an infinite time after the external neutron source is removed,

[0024] When t→∞, N(∞)→0, c i (∞)→0

[0025] The solution of this pattern (6) is:

[0026]

[0027] make And consider that Λ is much smaller than The first term Λ in the numerator can be ignored, and we have:

[0028]

[0029] This is the formula for measuring reactivity using the integral method of the source jumping method. As long as the neutron level N0 when the core state is stable before the source jumping and the integral neutron number after the source jumping are measured The subcriticality of the core can be obtained.

[0030] The preferred neutron source for measuring core subcriticality by the source-hopping method is californium ( 252 Cf) source, followed by a small-sized americium-beryllium ( 241When measuring reactivity by the source jumping method, the neutron source and the neutron detector are located on both sides of the reactor core. In order for the neutron detector to collect enough neutron signals emitted by the neutron source and attenuated by the core, the source strength of the neutron source is required to be high, generally requiring the source strength of the neutron source to be greater than 10 8 n / s.

[0031] In order to ensure that the core subcriticality does not change before and after the source jump, the external neutron source needs to be instantly jumped out of the core when measuring the core subcriticality using the source jump method. To achieve the instantaneous jump out of the neutron source, the common method is to use a neutron source control system (i.e., a rabbit system) to drive the neutron source. The rabbit system mainly includes an air pump, a gas storage tank, an air pipe, a neutron source direction conversion component, etc. However, due to the limitation of the air pump pressure of the rabbit system, the size of the neutron source needs to be reduced. Figure 1 A schematic diagram of the measurement arrangement of the source jumping method based on a radioactive neutron source is shown.

[0032] Then, during the management, use and storage of radioactive neutron sources, their high radioactivity can easily cause adverse effects on relevant personnel; at the same time, radioactive neutron sources have a low neutron yield and are more suitable for subcriticality measurements in small cores. Moreover, they are uncontrollable, and usually different cores require different radioactive neutron sources, which is costly. Summary of the invention

[0033] In order to reduce or avoid the safety risks, high cost or low applicability of the traditional source-hopping measurement technology using radioactive neutron sources, this application proposes a core subcriticality measurement method and system based on a neutron generator. This application uses a neutron generator to replace the radioactive neutron source in the traditional source-hopping method, eliminates the inherent risks in the management, use and storage of radioactive neutron sources (such as high radioactivity causing adverse effects on relevant personnel), and improves the safety of system operation; at the same time, after the neutron generator is powered off, it can be used as a conventional device, and the neutron generator has the advantages of generating monoenergetic neutrons, controllable neutron yield, mobility, and reusability, which can greatly reduce the equipment cost and provide high economic value for core measurement; in addition, the neutron yield of the neutron generator can be as high as 10 10 n / s, which is slightly higher than that of the californium source and 2 to 3 orders of magnitude higher than other neutron sources, improves the accuracy of core subcriticality measurement.

[0034] This application is implemented through the following technical solutions:

[0035] A method for measuring core subcriticality based on a neutron generator, the method comprising:

[0036] After the neutron generator and the neutron detector are installed and adjusted in the reactor core, the neutron generator is used to generate neutrons and maintain the stability of the reactor core;

[0037] After the core is stabilized for a preset time, the neutron generator is cut off and the core subcriticality is measured.

[0038] In some embodiments, the installation of the neutron generator and the neutron detector in the core satisfies:

[0039] The neutron generator and the neutron detector are arranged on opposite sides of the core, respectively, and the neutron generator, the neutron detector and the center of the core are on the same straight line.

[0040] In some embodiments, the use of the neutron generator to generate neutrons and maintain core stability specifically includes:

[0041] At some point, lift a safety bar to the top;

[0042] Turning on the neutron generator and maintaining the neutron yield of the neutron generator at a preset yield;

[0043] Lift the remaining safety rods to the top, and lift the adjustment rods according to the 1 / 2 principle, and during the process of lifting the rods, collect the neutron count rate using the neutron detector and monitor the neutron count changes through a measurement system connected to the neutron detector;

[0044] When the neutron count reaches a preset level, the neutron flux density at the neutron detector is maintained in a stable state by finely adjusting the adjustment rod, that is, the core is maintained in a stable state.

[0045] In some embodiments, the preset yield is 1×10 9 n / s.

[0046] In some embodiments, the shutting off of the neutron generator and measuring the core subcriticality specifically includes:

[0047] After the core maintains stability for a preset time, the neutron level when the core is in a stable state is measured by a measurement system;

[0048] Then, the neutron generator is cut off, and the integral value of the neutron count changing with time after the source jump is measured by a measurement system;

[0049] The core subcriticality is calculated based on the neutron level when the core is in a stable state and the integral value of the neutron count changing with time after the source jump.

[0050] In some embodiments, the core subcriticality measurement method further includes:

[0051] measuring the core subcriticality when the control rod to be tested is inserted into the core and the core subcriticality when the control rod to be tested is withdrawn from the core;

[0052] The difference between the subcriticality of the core when the control rod to be tested is withdrawn from the core and the subcriticality of the core when the control rod to be tested is inserted into the core is calculated to obtain the integral value of the control rod to be tested.

[0053] On the other hand, the present application proposes a core subcriticality measurement system based on a neutron generator, the core subcriticality measurement system comprising:

[0054] A start-up module, wherein the start-up module is configured to: after the neutron generator and the neutron detector are installed and adjusted in the core, use the neutron generator to generate neutrons and maintain the stability of the core;

[0055] And, a control module, wherein the control module is configured to: after the core is stabilized for a preset time, cut off the neutron generator and measure the subcriticality of the core.

[0056] In some embodiments, the core subcriticality measurement system further comprises:

[0057] A calculation module is configured to obtain an integral value of the control rod to be tested according to the measured core subcriticality when the control rod to be tested is inserted into the core and the core subcriticality when the control rod to be tested is withdrawn from the core.

[0058] In some embodiments, the calculation module includes:

[0059] A first data acquisition unit, wherein the first data acquisition unit is configured to: acquire a core subcriticality measured when a control rod to be tested is inserted into the core;

[0060] A second data acquisition unit, wherein the second data acquisition unit is configured to: acquire the core subcriticality measured when the control rod to be tested is raised out of the core;

[0061] And, a differential unit, wherein the differential unit is configured to calculate the difference between the core subcriticality obtained by the second data acquisition unit and the core subcriticality obtained by the first data acquisition unit to obtain an integral value of the control rod to be tested.

[0062] In some embodiments, the control module further includes:

[0063] A source jump unit, wherein the source jump unit is configured to: cut off the neutron generator after the core maintains stability for a preset time;

[0064] A counting unit, wherein the counting unit is configured to: measure and obtain the neutron level when the core state is stable and the integral value of the neutron count changing with time after the source jump;

[0065] And, a solution unit, wherein the solution unit is configured to calculate the core subcriticality according to the neutron level when the core state is stable and the integral value of the neutron count changing with time after the source jump.

[0066] The present application proposes a method and system for measuring core subcriticality based on a neutron generator, which uses a neutron generator to replace the radioactive neutron source in the traditional source-jumping method, thereby eliminating the inherent risks in the management, use, and storage of radioactive neutron sources (i.e., high radioactivity has an adverse effect on relevant personnel), and improves the safety of system operation.

[0067] The present application proposes a method and system for measuring the core subcriticality based on a neutron generator. The neutron generator used can be used as a conventional device after power failure. The neutron generator has the advantages of generating monoenergetic neutrons, controllable neutron yield, mobility, and reuse, which can greatly reduce equipment costs and provide high economic value for core measurement.

[0068] The present application proposes a method and system for measuring the core subcriticality based on a neutron generator. The neutron yield of the neutron generator can be as high as 10 10 n / s, which is slightly higher than that of the californium source and 2 to 3 orders of magnitude higher than other neutron sources. The high neutron yield is beneficial to the accuracy of measuring the core subcriticality by the source-hopping method, and provides technical support and technical reference for promoting the research on core measurement technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The drawings described herein are used to provide a further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation on the embodiments of the present application. In the drawings:

[0070] Figure 1 This is a schematic diagram of the measurement arrangement of the traditional source-hopping method based on a radioactive neutron source;

[0071] Figure 2 is a schematic diagram of the neutron generator structure;

[0072] Figure 3 This is a flow chart of a method for measuring core subcriticality according to an embodiment of the present application;

[0073] Figure 4 This is a schematic diagram of the measurement arrangement of the source jumping method based on the neutron generator in an embodiment of the present application;

[0074] Figure 5 This is a flow chart of installation and commissioning of the core, neutron detector and neutron generator of the embodiment of the present application;

[0075] Figure 6 This is a principle block diagram of a core subcriticality measurement system according to an embodiment of the present application.

[0076] Reference numerals and corresponding component names:

[0077] 1-mobile platform, 2-control system, 3-target nuclear component, 4-acceleration unit, 5-ion source, 6-high pressure chamber, 7-neutron detector, 8-core, 9-neutron generator. DETAILED DESCRIPTION

[0078] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with examples and drawings. The illustrative implementation scheme of the present application and its description are only used to explain the present application and are not intended to limit the present application.

[0079] Example:

[0080] The technology of measuring core subcriticality by the traditional source-hopping method usually uses a radioactive neutron source as an external neutron source. However, the radioactive neutron source is easy to cause adverse effects on relevant personnel during management, use and storage, and the neutron yield of the radioactive neutron source is uncontrollable. Different cores need to use different radioactive neutron sources, which is costly. In addition, the neutron yield of the radioactive neutron source is low, which is more suitable for measuring the subcriticality of small cores. If it is applied to large cores, the measurement accuracy of the core subcriticality may be reduced due to the low neutron yield. In view of this, this embodiment proposes a core subcriticality measurement method based on a neutron generator. The core subcriticality measurement method proposed in this embodiment uses a neutron generator to replace the radioactive neutron source in the traditional source-hopping method, which can eliminate the inherent risks of the radioactive neutron source, and the neutron generator has the advantages of generating monoenergetic neutrons, controllable neutron yield, mobility, and reusability, which greatly reduces the equipment cost.

[0081] The neutron generator mentioned in this embodiment refers to a device that can generate a neutron beam by bombarding a target nucleus with ions, and mainly includes an ion source 5, a high-pressure chamber 6, an acceleration unit 4, a control system 2, a mobile platform 1, and a target nucleus component 3. Figure 2 As shown. The function of the neutron generator is to produce a strong, controllable, single-energy, high-current neutron beam. The neutron generator can be used to carry out nuclear technology applications such as neutron cross-section measurement, neutron irradiation breeding, neutron detector calibration, neutron photography, and neutron activation analysis. For example, the neutron beam produced by the neutron generator is nearly monoenergetic, which is suitable for measuring the neutron cross-section data of different materials. The high-current neutron beam can also be used to calibrate the neutron detectors used in the various nuclear measurement systems, control and protection systems, and test measurement systems of the reactor to measure the sensitivity of each neutron detector and confirm whether the neutron detector is in a fully functional state.

[0082] like Figure 3 As shown, the core subcriticality measurement method proposed in this embodiment specifically includes the following steps:

[0083] Step 100, after the neutron generator and the neutron detector are installed and adjusted in the core, the neutron generator is used to generate neutrons and maintain the core stability.

[0084] When using the source jumping method to measure the core subcriticality, it is first necessary to stabilize the reactor under the action of an external neutron source (neutron generator), and then instantly jump out the neutron generator. At this time, the neutron flux density in the core will decay according to the core subcritical characteristics. The core subcriticality can be obtained by measuring the decay curve of the neutron flux density over time using an external neutron detector.

[0085] Therefore, in order to make the neutron flux density time decay curve measured by the neutron detector typically represent the core characteristics, the neutron generator 9 and the neutron detector 7 are arranged on opposite sides of the core 8, and the centers of the three are kept on the same straight line as much as possible, such as Figure 4 shown.

[0086] Based on the above principles, the installation and commissioning of the neutron generator 9, neutron detector 7, reactor core 8 and other components are completed. The installation and commissioning process is as follows: Figure 5 As shown in the figure, the installation and debugging process specifically includes: installation of the core lower grid plate, enclosure and other internal components; installation of the neutron detector and measuring instrument on the pile; installation of the fuel assembly, control rod, and poison rod; installation of the control rod drive mechanism; joint debugging of the core supporting nuclear measurement system, control and protection system, drive mechanism and other systems; fixed-point arrangement and debugging of the neutron generator outside the pile; and finally, arrangement and debugging of the neutron detector and the back-end jump source measurement system. It should be noted that the specific installation and debugging methods belong to the conventional technical means in this field and will not be described in detail here.

[0087] After the installation and commissioning of the neutron generator 9, neutron detector 7, core 8 and other components are completed, the reactor is operated according to the established steps, and the neutron generator is turned on to introduce neutrons into the subcritical reactor and the control rod is raised, so that the overall neutron production rate of the reactor itself after adding external neutrons is equal to the neutron disappearance rate, that is, the entire system is in a neutron stable state. This embodiment takes a typical pressurized water reactor as an example, which is composed of a solid fuel assembly, a control rod, a poison rod, a coolant water, etc. The specific operation steps include:

[0088] At a certain initial moment, lift a certain safety bar to the top;

[0089] Then the neutron generator is turned on to maintain its neutron yield at a preset level. The preset yield can be 1×10 9 n / s, this neutron yield is selected to meet the needs of various types of reactors.

[0090] The remaining safety rods are lifted to the top, and the adjusting rods are lifted according to the 1 / 2 principle. During the rod lifting process, the neutron count rate is collected by the neutron detector at the rear end, and the neutron count changes are monitored by the source jumping measurement system connected to the neutron detector. When the neutron count reaches a certain level, the adjusting rods are slightly adjusted to maintain the neutron flux density at the neutron detector in a stable state, that is, the core is in a stable state, and the neutron count level is N0.

[0091] Step 200: After the core is stabilized for a preset time, the neutron generator is turned off and the core subcriticality is measured.

[0092] By starting the neutron generator and lifting the control rod to keep the neutron flux density at the neutron detector stable for a certain period of time, the neutron level N0 when the core state is stable is measured using the source jumping method measurement system, and then the neutron generator is cut off, that is, the source jumping operation is realized. At this time, the remaining neutron count will decay over time according to the inherent subcritical characteristics of the core, and the integral value of the neutron count changing with time is measured using the source jumping method measurement system. The core subcriticality can be obtained. The specific calculation principle is as described in the above background technology, that is:

[0093]

[0094] In the formula, ρ is the reactivity, β is the delayed neutron fraction, and λ is i is the delayed neutron decay constant, N0 is the neutron count level when the core state is stable, and N(t) is the neutron count level at time t.

[0095] For a certain core, β eff , i , α i are all known quantities, so this embodiment measures the neutron level N0 when the core state is stable before the source jump and the integrated neutron number after the source jump. That is, the subcriticality ρ of the core is calculated using the above formula.

[0096] In addition, when using the source-hopping method to measure core subcriticality, a neutron generator can be used to replace the traditional radioactive neutron source, that is, the neutron generator can be used to realize the instantaneous jump out of the external neutron source in the source-hopping method measurement. Since the neutron generator can instantaneously introduce neutrons when powered on and instantaneously cut off neutrons when powered off, the application of neutron generators to the source-hopping method to measure core criticality has technical advantages such as strong controllability, which is conducive to improving measurement accuracy.

[0097] Furthermore, the core subcriticality measurement method proposed in this embodiment also includes:

[0098] Step 300, obtaining the integral value of the control rod to be tested according to the core subcriticality measured when the control rod to be tested is inserted into the core and the core subcriticality measured when the control rod to be tested is withdrawn from the core.

[0099] Step 200 is used to measure the subcriticality of the core when the control rod to be tested is arranged in the core (i.e., inserted into the core) and when the control rod to be tested is withdrawn from the core. The subcriticality of the core measured when the control rod to be tested is withdrawn from the core is subtracted from the subcriticality of the core measured when the control rod to be tested is inserted into the core to obtain the integral value of the control rod to be tested.

[0100] The core subcriticality method proposed in this embodiment uses a neutron generator to replace the traditional radioactive neutron source to achieve core subcriticality or control rod integral value and other core subcriticality performance measurements, which can eliminate the safety risks in the management, use, and storage of radioactive neutron sources. After the neutron generator is powered off, it can also be used as a conventional device to ensure the safety performance of the core. In addition, the neutron generator has the advantages of generating monoenergetic neutrons, controllable neutron yield, mobility, and reuse, which can greatly reduce equipment costs and provide high economic value for core measurement. In addition, the neutron yield of the neutron generator can be as high as 10 10 n / s, which is slightly higher than that of the californium source and 2 to 3 orders of magnitude higher than other neutron sources. The high neutron yield is beneficial to the accuracy of measuring the core subcriticality by the source-hopping method, and provides technical support and technical reference for promoting the research on core measurement technology.

[0101] Based on the same technical concept as above, this embodiment also proposes a core subcriticality measurement system based on a neutron generator, such as Figure 6 As shown, the core subcriticality measurement system proposed in this embodiment includes:

[0102] The startup module is configured to: after the installation and joint adjustment of the neutron generator and the neutron detector in the core, use the neutron generator to generate neutrons and maintain the stability of the core. When the core subcriticality is measured by the source jump method, the reactor must first be in a stable state under the action of an external neutron source (neutron generator), and then the neutron generator is instantly jumped out. At this time, the neutron flux density in the core will decay according to the subcritical characteristics of the core. The core subcriticality can be obtained by measuring the decay curve of the neutron flux density over time using the neutron detector outside the core. It should be noted that the specific installation and joint adjustment, as well as the method of starting and maintaining stability are as described in the above step 100, and will not be repeated here.

[0103] And, a control module, the control module is configured to: cut off the neutron generator and measure the subcriticality of the core. After starting the neutron generator and raising the control rod to keep the neutron flux density at the neutron detector stable for a certain period of time, the neutron level N0 when the core state is stable is measured using the source jumping method measurement system, and then the neutron generator is cut off, that is, the source jumping operation is realized. At this time, the remaining neutron count will decay over time according to the inherent subcritical characteristics of the core, and the integral value of the neutron count changing over time is measured using the source jumping method measurement system. The core subcriticality can be obtained.

[0104] Furthermore, the core subcriticality measurement system proposed in this embodiment also includes:

[0105] A calculation module is configured to obtain an integral value of the control rod to be tested according to the core subcriticality measured when the control rod to be tested is inserted into the core and the core subcriticality measured when the control rod to be tested is withdrawn from the core.

[0106] Furthermore, the control module also includes:

[0107] The source hopping unit is configured to: after the core state remains stable for a certain period of time, cut off the neutron generator, that is, implement the source hopping operation; the specific source hopping operation process is as described in the above step 200, which will not be repeated here.

[0108] The counting unit is configured to measure the neutron level when the core state is stable and the integral value of the remaining neutron count after the source jump operation over time; the specific measurement process is as described in the above step 200 and will not be repeated here.

[0109] And, a solution unit, the solution unit is configured to: calculate the subcriticality of the core according to the neutron level when the core state is stable and the integral value of the remaining neutron count after the source jump operation over time. The specific solution principle is as described in the above step 200, and will not be repeated here.

[0110] Furthermore, the calculation module includes:

[0111] A first data acquisition unit, the first data acquisition unit is configured to: acquire a core subcriticality measured when a control rod to be tested is inserted into the core;

[0112] A second data acquisition unit, the second data acquisition unit is configured to: acquire the core subcriticality measured when the control rod to be tested is raised out of the core;

[0113] And, a differential unit, the differential unit is configured to: calculate the difference between the core subcriticality obtained by the second data acquisition unit and the core subcriticality obtained by the first data acquisition unit, which is the integral value of the control rod to be tested.

[0114] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0115] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0116] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0117] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0118] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only the specific implementation method of the present application and is not intended to limit the scope of protection of the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for measuring core subcriticality based on a neutron generator, characterized in that: The core subcriticality measurement method comprises: After the neutron generator and the neutron detector are installed and adjusted in the reactor core, the neutron generator is used to generate neutrons and maintain the stability of the reactor core; After the core is stabilized for a preset time, the neutron generator is cut off and the core subcriticality is measured.

2. The method for measuring core subcriticality based on a neutron generator according to claim 1, characterized in that: The installation of the neutron generator and neutron detector in the core meets the following requirements: The neutron generator and the neutron detector are arranged on opposite sides of the core, respectively, and the neutron generator, the neutron detector and the center of the core are on the same straight line.

3. The method for measuring core subcriticality based on a neutron generator according to claim 1, characterized in that: The method of using the neutron generator to generate neutrons and maintain core stability specifically includes: At some point, lift a safety bar to the top; Turning on the neutron generator and maintaining the neutron yield of the neutron generator at a preset yield; Lift the remaining safety rods to the top, and lift the adjustment rods according to the 1 / 2 principle, and during the process of lifting the rods, collect the neutron count rate using the neutron detector and monitor the neutron count changes through a measurement system connected to the neutron detector; When the neutron count reaches a preset level, the neutron flux density at the neutron detector is maintained in a stable state by finely adjusting the adjustment rod, that is, the core is maintained in a stable state.

4. The method for measuring core subcriticality based on a neutron generator according to claim 3, characterized in that: For small and medium-sized reactors, the preset yield is 1×10 9 n / s.

5. The method for measuring core subcriticality based on a neutron generator according to claim 1, characterized in that: The method of cutting off the neutron generator and measuring the core subcriticality specifically includes: After the core maintains stability for a preset time, the neutron level when the core is in a stable state is measured by a measurement system; Then, the neutron generator is cut off, and the integral value of the neutron count changing with time after the source jump is measured by a measurement system; The core subcriticality is calculated based on the neutron level when the core is in a stable state and the integral value of the neutron count changing with time after the source jump.

6. A method for measuring core subcriticality based on a neutron generator according to any one of claims 1 to 5, characterized in that: The core subcriticality measurement method further comprises: measuring the core subcriticality when the control rod to be tested is inserted into the core and the core subcriticality when the control rod to be tested is withdrawn from the core; The difference between the subcriticality of the core when the control rod to be tested is withdrawn from the core and the subcriticality of the core when the control rod to be tested is inserted into the core is calculated to obtain the integral value of the control rod to be tested.

7. A core subcriticality measurement system based on a neutron generator, characterized in that: The core subcriticality measurement system comprises: A start-up module, wherein the start-up module is configured to: after the neutron generator and the neutron detector are installed and adjusted in the core, use the neutron generator to generate neutrons and maintain the stability of the core; And, a control module, wherein the control module is configured to: after the core is stabilized for a preset time, cut off the neutron generator and measure the subcriticality of the core.

8. A core subcriticality measurement system based on a neutron generator according to claim 7, characterized in that: The core subcriticality measurement system further comprises: A calculation module is configured to obtain an integral value of the control rod to be tested according to the measured core subcriticality when the control rod to be tested is inserted into the core and the core subcriticality when the control rod to be tested is withdrawn from the core.

9. A core subcriticality measurement system based on a neutron generator according to claim 8, characterized in that: The calculation module comprises: A first data acquisition unit, wherein the first data acquisition unit is configured to: acquire a core subcriticality measured when a control rod to be tested is inserted into the core; a second data acquisition unit, the second data acquisition unit being configured to: acquire the core subcriticality measured when the control rod to be tested is raised out of the core; And, a differential unit, wherein the differential unit is configured to calculate the difference between the core subcriticality obtained by the second data acquisition unit and the core subcriticality obtained by the first data acquisition unit to obtain an integral value of the control rod to be tested.

10. A core subcriticality measurement system based on a neutron generator according to any one of claims 7 to 9, characterized in that: The control module also includes: A source jump unit, wherein the source jump unit is configured to: cut off the neutron generator after the core maintains stability for a preset time; A counting unit, wherein the counting unit is configured to: measure and obtain the neutron level when the core state is stable and the integral value of the neutron count changing with time after the source jump; And, a solution unit, wherein the solution unit is configured to calculate the core subcriticality according to the neutron level when the core state is stable and the integral value of the neutron count changing with time after the source jump.

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