Method and system for determining operating parameters of a nuclear reactor fissile chamber detector

Abstract

The present application relates to a kind of nuclear reactor fissure chamber detector operating parameter determination method and system, its method includes: the output current relationship information of measured detector is acquired;According to the output current relationship information, the operating voltage test range of the measured detector is determined;The working gas pressure of the measured detector is in turn set to multiple predetermined gas pressure values, and after each time setting the working gas pressure, the measured detector is controlled to work based on the operating voltage test range, and the output current when the measured detector is injected with neutron beam is acquired and determined according to each predetermined gas pressure value corresponding count rate data;According to each count rate data, the ideal operating parameter of the measured detector is determined.The present application can help staff to determine the ideal operating parameter of fissure chamber detector, improve the stability and reliability of detector.

Description

Technical Field

[0001] This invention relates to the field of fission chamber detector technology, and more particularly to a method and system for determining the operating parameters of a nuclear reactor fission chamber detector. Background Technology

[0002] The fission chamber detector is a primary instrument in the intermediate range of a nuclear instrumentation system and is one of the crucial devices for ensuring the safe operation of the reactor. Therefore, its performance is critical to maintaining the safe operation of a nuclear power plant. While the working gas pressure of the fission chamber detector has a significant impact on its performance, it is also affected by other factors such as ion drift velocity and electric field strength. Due to a lack of sufficient verification and analysis of the impact of these factors on its operation, the interaction of multiple factors cannot be ruled out. This results in a lack of systematic and reliable technical means for operators to improve detector performance by adjusting operating parameters. To improve reactor safety, nuclear power plants urgently need a technical means to accurately determine the operating parameters of the fission chamber detector. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method and system for determining the operating parameters of a nuclear reactor fission chamber detector.

[0004] The technical solution adopted by this invention to solve its technical problem is: constructing a method for determining the operating parameters of a nuclear reactor fission chamber detector, comprising:

[0005] Obtain the output current relationship information of the detector under test;

[0006] The operating voltage test range of the detector under test is determined based on the output current relationship information.

[0007] The working gas pressure of the detector under test is sequentially set to a variety of predetermined gas pressure values. After each setting of the working gas pressure, the detector under test is controlled to work based on the working voltage test range. The count rate data corresponding to each predetermined gas pressure value is obtained and determined according to the output current of the detector under test when it is injected with a neutron beam.

[0008] The ideal operating parameters of the detector under test are determined based on the count rate data.

[0009] Preferably, the step of obtaining the output current relationship information of the detector under test includes: constructing a simulation model equivalent to the circuit structure of the detector under test, and analyzing the simulation model to determine the output current relationship information.

[0010] Preferably, the step of constructing a simulation model equivalent to the circuit structure of the detector under test includes:

[0011] Construct a circuit schematic equivalent to the circuit structure of the detector under test to obtain an initial circuit model;

[0012] The circuit structure of the initial circuit model is simplified to obtain the simulation model;

[0013] The simulation model includes a power supply, an ionization chamber equivalent module, a fission chamber equivalent capacitor C1, a load equivalent resistor R0, and a load equivalent capacitor C2. The positive terminal of the power supply is connected to the first terminal of the ionization chamber equivalent module, and the second terminal of the ionization chamber equivalent module is connected to the negative terminal of the power supply via the load equivalent resistor R0 and the load equivalent capacitor C2.

[0014] Preferably, the step of analyzing the simulation model to determine the output current relationship information includes:

[0015] The expression for the output current of the detector under test is determined based on the law of conservation of energy and the circuit structure of the simulation model.

[0016] The output current expression is as follows:

[0017]

[0018] Where I(t) represents the output current of the detector under test, V0 represents the operating voltage of the detector under test, and V(t) represents the second terminal voltage of the ionization chamber equivalent module. This indicates that at time t, the j-th positive ion is located in the fission chamber. electric field strength, This represents the drift velocity of the j-th positive ion in the fission chamber at time t. This indicates that at time t, the k-th electron is located in the fission chamber. electric field strength, It represents the drift velocity of the k-th electron in the fission chamber at time t.

[0019] Preferably, the step of determining the operating voltage test range of the detector under test based on the output current relationship information includes:

[0020] Set the lower limit voltage of the working voltage test range to a voltage value greater than N·V(t), where N is a positive number.

[0021] Preferably, the range of the predetermined air pressure values ​​is from 2.0 atm to 6.0 atm.

[0022] Preferably, the step of controlling the operation of the detector under test based on the operating voltage test range, acquiring and determining the count rate data corresponding to each predetermined air pressure value based on the output current of the detector under test, includes:

[0023] Multiple operating voltage points are determined based on the operating voltage test range;

[0024] The operating voltage of the detector under test is sequentially set to the plurality of operating voltage points;

[0025] After each operating voltage point is set, the following steps are performed: the neutron source is controlled to inject a neutron beam into the detector under test, and the output current of the detector under test is acquired multiple times within a set time period; the average count rate corresponding to the operating voltage point is calculated based on the multiple acquired output currents.

[0026] Count rate data is generated based on the average count rate at various operating voltage points for each of the predetermined air pressure values.

[0027] Preferably, the step of determining the ideal operating parameters of the detector under test based on the count rate data includes:

[0028] Based on the count rate data, multiple plateau characteristic curves corresponding one-to-one with each of the predetermined air pressure values ​​are fitted;

[0029] Determine the corresponding plateau characteristic data for each of the aforementioned plateau characteristic curves;

[0030] The ideal plateau voltage range and ideal working gas pressure range of the detector under test are determined based on the plateau characteristic data.

[0031] Preferably, the plateau characteristic data includes plateau voltage, plateau length, and plateau inclination;

[0032] The step of determining the ideal plateau voltage range and ideal working gas pressure range of the detector under test based on the plateau characteristic data includes:

[0033] For each of the plateau characteristic curves, the following is performed: determine whether the plateau length of the plateau characteristic curve is greater than a set plateau length; if so, mark the plateau characteristic curve.

[0034] When at least one of the plateau characteristic curves is marked, for each marked plateau characteristic curve, the following is performed: determine whether the plateau slope of the plateau characteristic curve is less than the set plateau slope; if so, the plateau characteristic curve is defined as a qualified curve.

[0035] The ideal working gas pressure range is determined based on the predetermined gas pressure values ​​of all the qualified curves.

[0036] The ideal plateau voltage range is determined based on the plateau voltage of all the qualified curves.

[0037] Furthermore, this invention also constructs a system for determining the operating parameters of a nuclear reactor fission chamber detector, comprising:

[0038] Gas supply device, used to provide working gas to the detector under test;

[0039] A neutron source, used to provide the detector under test with a neutron beam for the experiment;

[0040] The testing device includes an acquisition unit, a range determination unit, a voltage control unit, a gas supply control unit, a counting unit, and a parameter determination unit;

[0041] The acquisition unit is used to acquire the output current relationship information of the detector under test;

[0042] The range determination unit is used to determine the operating voltage test range of the detector under test.

[0043] The voltage control unit is used to control the operation of the detector under test based on the operating voltage test range;

[0044] The gas supply control unit is used to control the gas supply device to sequentially provide the detector under test with working gas pressures of multiple predetermined gas pressure values.

[0045] The counting unit is used to acquire the output current of the detector under test when it is injected with a neutron beam and operates based on the working voltage test range at each of the predetermined gas pressure values, and to determine the count rate data corresponding to each of the predetermined gas pressure values ​​based on the output current;

[0046] The parameter determination unit is used to determine the ideal operating parameters of the detector under test based on the count rate data.

[0047] Preferably, the gas supply control unit includes:

[0048] A gas supply pipe is used for mechanical connection between the detector under test and the gas supply device;

[0049] A valve, installed on the gas supply pipeline, is used to regulate the flow rate of the working gas input to the detector under test;

[0050] A pressure gauge is used to measure the working gas pressure of the detector under test.

[0051] Preferably, the counting unit includes:

[0052] An amplifier is used to amplify the output current of the detector under test.

[0053] A single-channel analyzer is used to identify single-channel pulses in the amplified output current that meet set conditions;

[0054] A scaler is used to count the single-channel pulses that meet the set conditions and output the count information;

[0055] A counter is used to determine the count rate data corresponding to each of the predetermined air pressure values ​​based on the count information.

[0056] Preferably, the nuclear reactor fission chamber detector operating parameter determination system further includes:

[0057] An air extraction device is used to extract the air from the detector under test before supplying working gas to the detector under test, and to ensure that the air pressure of the detector under test does not exceed a set pressure value.

[0058] A heat preservation device is used to keep the detector under test within a set temperature range during evacuation.

[0059] Implementing the technical solution of this invention can help staff determine the ideal operating parameters of the fission chamber detector, increase the probability of fission fragments ionizing in the fission chamber detector, and allow fragment energy to be fully deposited in the sensitive area. This can increase the amplitude of the output current, improve the signal-to-noise ratio of the detector, and help improve the sensitivity and detection efficiency of the detector. This makes the detector more capable of detecting fission fragments and is of great significance for improving the working stability and reliability of the detector. Attached Figure Description

[0060] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0061] Figure 1 This is a flowchart of a method for determining the operating parameters of a nuclear reactor fission chamber detector in some embodiments of the present invention;

[0062] Figure 2 These are circuit schematics of the initial circuit model in some embodiments of the present invention;

[0063] Figure 3 These are circuit schematics of simulation models in some embodiments of the present invention;

[0064] Figure 4 yes Figure 3 A further simplified circuit schematic;

[0065] Figure 5 This is a flowchart of step S30 in some embodiments of the present invention;

[0066] Figure 6 This is a flowchart of step S40 in some embodiments of the present invention;

[0067] Figure 7 These are the plateau characteristic curves in some embodiments of the present invention when the predetermined air pressure values ​​are 2.0 atm to 6.0 atm;

[0068] Figure 8This is a schematic diagram of the structure of the nuclear reactor fission chamber detector operating parameter determination system in some embodiments of the present invention;

[0069] Figure 9 This is a schematic diagram of the gas supply control unit in some embodiments of the present invention. Detailed Implementation

[0070] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0071] It should be noted that the flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0072] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0073] Figure 1 This is a flowchart illustrating a method for determining the operating parameters of a nuclear reactor fission chamber detector in some embodiments of the present invention. This method is used to determine the ideal operating parameters of the fission chamber detector, ensuring that the detector meets the requirements for sensitivity and detection efficiency, which is of great significance for improving the detector's operational stability and reliability. Furthermore, the operating parameters of the fission chamber detector include the working gas pressure and operating voltage.

[0074] It should be noted that, in this invention, the fission chamber detector under test is simply referred to as the detector under test.

[0075] Please see Figure 1 The method for determining the operating parameters of the nuclear reactor fission chamber detector may include steps S10, S20, S30 and S40.

[0076] Step S10 includes: acquiring the output current relationship information of the detector under test. In this embodiment, the current relationship information includes the relationship between the output current of the detector under test and the operating parameters and electronic device parameters of the detector under test, and the electronic devices include hybrid capacitors and amplifiers of devices such as ionization chamber, fission chamber capacitor, load resistor, fission chamber connecting cable, etc.

[0077] In some embodiments, the output current relationship information of the detector under test can be determined by: constructing a simulation model equivalent to the circuit structure of the detector under test, and analyzing the simulation model to determine the output current relationship information.

[0078] In some embodiments, the simulation model can be constructed by: constructing a circuit schematic equivalent to the circuit structure of the detector under test to obtain an initial circuit model; simplifying the circuit structure of the initial circuit model to obtain a simulation model.

[0079] In some embodiments, please refer to Figure 2 The initial circuit model may include a power supply 100, an ionization chamber equivalent module 200, a fission chamber equivalent capacitor C1, a load resistor R1, hybrid capacitance C' of the fission chamber connecting cable, and an amplifier 300, which includes an amplifier equivalent resistor R. i and amplifier equivalent capacitance C i Accordingly, the steps to simplify the circuit structure of the initial circuit model may include: equipping all capacitors connected in parallel in the simulation model with an equivalent load capacitor, and equipping all resistors connected in parallel in the simulation model with an equivalent load resistor, thereby obtaining the simulation model. For details, please refer to... Figure 3 The simulation model may include a power supply 100, an ionization chamber equivalent module 200, a fission chamber equivalent capacitor C1, a load equivalent resistance R0, and a load equivalent capacitor C2. The positive terminal of the power supply 100 is connected to the first terminal of the ionization chamber equivalent module 200. One end of the second terminal of the ionization chamber equivalent module 200 is connected to the negative terminal of the power supply 100 via the load equivalent resistance R0, and the other end of the second terminal of the ionization chamber equivalent module 200 is connected to the negative terminal of the power supply 100 via the load equivalent capacitor C2.

[0080] In some embodiments, the output current relationship information can be clarified by determining the output current expression of the detector under test based on the energy conservation law and the circuit structure of the simulation model.

[0081] Specifically, analyze Figure 3 Therefore, the output power of power supply 100 can be expressed as: W(t) = I s (t)·V0, due to This expression is denoted as Equation (1). Further derivation yields: This formula is denoted as Equation (2). W(t) represents the output power of power supply 100, and I s (t) represents the output current of power supply 100, and V0 represents the output voltage of power supply 100 (i.e., the operating voltage of the detector under test). This represents the current flowing through the equivalent resistance R0 of the load. This represents the current flowing through the equivalent capacitance C2 of the load.

[0082] The total power of resistor R0 and capacitor C2 can be expressed as: The formula is denoted as Equation (3), where W1(t) represents the total power of resistor R0 and capacitor C2, and V(t) represents the second terminal voltage of the ionization chamber equivalent module.

[0083] The power of the fission chamber equivalent capacitance C1 can be expressed as: This formula is denoted as Equation (4). W2(t) represents the power of the equivalent capacitance C1 of the fission chamber, and C1 represents the capacitance value of the equivalent capacitance C1 of the fission chamber.

[0084] The gravity power consumed by the drift of positive ions and electrons in the ionization of the equivalent module 200 under the action of an electric field can be expressed as: This equation is denoted as equation (4). W3(t) represents the heavy power consumed by the drift of positive ions and electrons. This indicates that at time t, the j-th positive ion is located in the fission chamber. electric field strength, This represents the drift velocity of the j-th positive ion in the fission chamber at time t. This indicates that at time t, the k-th electron is located in the fission chamber. electric field strength, It represents the drift velocity of the k-th electron in the fission chamber at time t.

[0085] Based on the law of conservation of energy, we can obtain equation (5): W(t) = W1(t) + W2(t) + W3(t). By transforming equations (2) to (5), we can obtain... This expression is denoted as expression (6). Wherein, This formula is denoted as Equation (7). It should be noted that V(t) is related to the resistance and capacitance in the circuit of the detector being tested.

[0086] Comparing equations (1) and (6), we can see that I(t) is larger than Is(t), and the difference is... This is the current value when V(t) is applied to the equivalent capacitance C1 of the fission chamber. Therefore, I(t) is the sum of the currents flowing through the resistor R0, capacitor C2, and its own capacitance C1. So I(t) can be used as the total current signal output by the fission chamber when the load resistance R1≠0, that is, the output current when the voltage applied to the fission chamber C1 remains constant at V0, which is the current value of the output circuit of the fission chamber when R1=0. Furthermore, if V0>>V(t), then equation (7) can also be written as: This formula is denoted as Equation (8). If V0 >> V(t), comparing Equation (7) and Equation (8), it can be seen that the current value output by the fission chamber is basically the same in the two cases of R1 = 0 and R1 ≠ 0. That is, I(t) in Equation (8) can represent the output current of the detector under test.

[0087] Furthermore, as shown in equation (8), the output current of the detector under test is independent of the resistance and capacitance in the detector's circuit. Therefore, the ionization chamber can be considered equivalent to a current source. Based on this, the... Figure 3 After simplification, we can obtain Figure 4 The circuit diagram shown is used. Figure 4 In equation (2-10), C0 = C1 + C2. It can be seen that the potential difference between the two plates of the fission chamber (or ionization chamber) remains unchanged. The output current I0(t) is contributed only by the drift of all positive ions and electrons in the sensitive volume and is independent of the external circuit parameters R0 and C0.

[0088] The working gas inside the fission chamber detector absorbs the energy carried by fission fragments after the nuclear reaction and ionizes them into positive ions and electrons. Therefore, easily ionizable gases (such as Ar) are typically used as the working gas inside the fission chamber detector. From the above analysis of the fission chamber detector, the amplitude of the output pulse signal is contributed by the drift of all positive ions and electrons within the sensitive volume. In reality, it is related to the drift velocity and the ionization probability generated along the drift path. The ion drift velocity is directly proportional to the electric field strength and inversely proportional to the gas pressure, i.e., u... + =μ + ξ / P, this formula is denoted as (9), u + μ represents the ion drift velocity. + Let V0 represent the correlation coefficient, ξ represent the electric field strength, and P represent the working gas pressure. That is, when V0 >> V(t), as the working gas pressure increases, the probability of fission fragments ionizing within the working region will increase, and the fragment energy will be fully deposited within the sensitive region, resulting in a larger output pulse amplitude from the fission chamber. As shown in equation (9), when the working gas pressure increases, the drift velocity of ions within the working region decreases; therefore, the plateau voltage (equivalent to increasing the electric field strength) needs to be increased to compensate for the increase in working gas pressure.

[0089] It should be noted that the purpose of analyzing the simulation model is to clarify the relationship between the output current of the detector under test and some influencing factors, in order to prepare for minimizing the number of factors affecting the output current. This allows staff to adjust the performance of the fission chamber detector by setting a smaller number of working parameters, simplifying the working parameter setting process and playing a positive role in improving work efficiency.

[0090] Step S20 includes: determining the operating voltage test range of the detector under test based on the output current relationship information.

[0091] From the analysis of equations (7) to (8) above, it can be seen that when V0 is set to a value much greater than V(t), the influence of the hardware circuit of the fission chamber detector can be eliminated, and the detector performance can be adjusted by setting the working gas pressure and working voltage of the fission chamber detector. Therefore, in some embodiments, the working voltage test range of the detector under test can be determined by setting the lower limit voltage of the working voltage test range to a voltage value greater than N·V(t), thereby eliminating or ignoring the influence of the electronic components of the detector under test on the output current. Wherein, N is a positive number.

[0092] It should be noted that the voltage V(t) at the second terminal of the ionization chamber equivalent module is determined by the actual circuit structure of the detector under test. This data can usually be obtained from the manufacturer or measured using existing techniques. N can be a positive number not less than 5, thus ensuring that the influence of V(t) can be ignored.

[0093] Because some existing fission chamber detectors have a small V(t), in some embodiments, the operating voltage test range can be set to 100V to 900V.

[0094] Step S30 includes: sequentially setting the working gas pressure of the detector under test to a variety of predetermined gas pressure values, and after each setting of the working gas pressure, controlling the operation of the detector under test based on the working voltage test range, acquiring and determining the count rate data corresponding to each predetermined gas pressure value based on the output current of the detector under test when injected with a neutron beam.

[0095] In some embodiments, it can be achieved by executing Figure 5 Steps S301 to S304 shown are used to determine the count rate data corresponding to each predetermined air pressure value.

[0096] Step S301 includes: determining multiple operating voltage points based on the operating voltage test range. Specifically, multiple operating voltage points can be extracted from the operating voltage test range based on a set voltage width. These multiple operating voltage points can be represented as: Vmin, Vmin+VK, Vmin+2·VK, ..., Vmin+m·VK, Vmax. Vmin represents the lower limit voltage of the operating voltage test range, VK represents the set voltage width, m is a natural number, and Vmax represents the upper limit voltage.

[0097] In some embodiments, the voltage width is preferably set to 100V. Accordingly, when the working voltage test range is 100V to 900V, the multiple working voltage points include 100V, 200V, 300V, 400V, 500V, 600V, 700V, 800V, and 900V.

[0098] Step S302 includes: sequentially setting the operating voltage of the detector under test to multiple operating voltage points.

[0099] Step S303 includes: after each operating voltage point is set, controlling the neutron source to inject a neutron beam into the detector under test, acquiring the output current of the detector under test multiple times within a set time period; and calculating the average count rate corresponding to the operating voltage point based on the multiple acquired output currents.

[0100] Specifically, after each time the operating voltage of the detector under test is set to a certain operating voltage point, a neutron beam with a stable flux rate is injected into the detector to allow it to sense the neutron beam. Then, the output current of the detector under test is repeatedly acquired within a set time period. Each acquired output current can characterize the number of neutrons detected by the detector under test within the set time period at that operating voltage point. By obtaining multiple neutron counts, the ratio of the average of these multiple neutron counts to the set time period can be calculated to obtain the average count rate at the corresponding predetermined pressure value at that operating voltage point.

[0101] In some embodiments, the output current of the detector under test can be acquired three times within a set time period, which can be 20 seconds. Additionally, this step can inject a flux-stable neutron beam into the detector under test using an existing neutron source.

[0102] Step S304 includes generating count rate data based on the average count rate of various predetermined air pressure values ​​at multiple operating voltage points. Specifically, the count rate data includes the average count rate of each predetermined air pressure value at multiple operating voltage points.

[0103] In some embodiments, the range of preset air pressure values ​​can be from 2.0 atm to 6.0 atm. Further, the preset air pressure values ​​may specifically include 2.0 atm, 3.0 atm, 4.0 atm, 5.0 atm, and 6.0 atm.

[0104] Step S40 includes: determining the ideal operating parameters of the detector under test based on the count rate data.

[0105] In some embodiments, it can be achieved by executing Figure 6 Steps S401 to S403 shown are used to determine the ideal operating parameters. These ideal operating parameters include the ideal plateau voltage range and the ideal working gas pressure range.

[0106] Step S401 includes: fitting multiple plateau characteristic curves corresponding one-to-one with each predetermined air pressure value based on the count rate data. In this step, the horizontal axis of the plateau characteristic curve can be the operating voltage, and the vertical axis can be the average count rate, which facilitates the analysis of the trend changes of the plateau characteristic curve.

[0107] Step S402 includes: determining the corresponding plateau characteristic data for each plateau characteristic curve. The plateau characteristic data may include plateau voltage, plateau length, and plateau inclination.

[0108] Step S403 includes: determining the ideal plateau voltage range and ideal working gas pressure range of the detector under test based on the plateau characteristic data.

[0109] Furthermore, the ideal plateau voltage range and ideal working gas pressure range of the detector under test can be determined by performing the following steps: For the plateau length of each plateau characteristic curve, determine whether the plateau length of the plateau characteristic curve is greater than the set plateau length; if so, mark the plateau characteristic curve; when at least one plateau characteristic curve is marked, for each marked plateau characteristic curve, determine whether the plateau slope of the plateau characteristic curve is less than the set plateau slope; if so, define the plateau characteristic curve as a qualified curve; determine the ideal working gas pressure range based on the predetermined gas pressure values ​​of all qualified curves; determine the ideal plateau voltage range based on the plateau voltage of all qualified curves.

[0110] In some embodiments, the plateau length can be set to 300VDC, and the plateau slope can be set to 3% / 100VDC. It should be noted that the calculation of plateau voltage, plateau length, and plateau slope should refer to existing technologies, and will not be elaborated here.

[0111] For ease of understanding, the detailed process of steps S30 and S40 is described below through a specific embodiment. In this specific embodiment, multiple operating voltage points include 100V, 200V, 300V, 400V, 500V, 600V, 700V, 800V, and 900V; multiple predetermined air pressure values ​​include 2.0atm, 3.0atm, 4.0atm, 5.0atm, and 6.0atm; the set time is 20 seconds; and the number of times the output current of the detector under test is acquired within the set time is 3.

[0112] Table 1 shows the count rate data when the predetermined air pressure is 2.0 atm. The count rate data for other predetermined air pressure values ​​are similar to those in Table 1 and will not be shown here.

[0113]

[0114] Table 1

[0115] Figure 7 These are plateau characteristic curves for predetermined air pressure values ​​ranging from 2.0 atm to 6.0 atm in some embodiments of the present invention. Curve (a) is the plateau characteristic curve at 2.0 atm, curve (b) is the plateau characteristic curve at 3.0 atm, curve (c) is the plateau characteristic curve at 4.0 atm, curve (d) is the plateau characteristic curve at 5.0 atm, and curve (e) is the plateau characteristic curve at 6.0 atm.

[0116] It should be noted that plateau voltage refers to the voltage range in which the average count rate of the fission chamber detector remains essentially constant or the plateau slope is less than a certain value. Therefore, analyzing curves (a) to (e) yields Table 2:

[0117] 2.0 atm 200-900 700 0.93 3.0 atm 200-900 700 0.90 4.0 atm 300-900 600 0.71 5.0 atm 500-900 400 1.73 6.0 atm 500-900 400 3.52

[0118] If the set plateau length is 300VDC and the set plateau slope is 3% / 100VDC, then it can be determined that predetermined gas pressure values ​​from 2.0atm to 5.0atm can meet the above requirements. It should be noted that the shorter the plateau slope, the better the quality of the detector. Therefore, in some embodiments, when the number of predetermined gas pressure values ​​that simultaneously meet the requirements of the set plateau length and set plateau slope is greater than two, the two predetermined gas pressure values ​​with the smallest plateau slope among all the predetermined gas pressure values ​​that meet the above requirements are taken as the ideal working gas pressure range. That is, the ideal working gas pressure range in this embodiment is 3.0atm to 4.0atm. Further, analysis of the plateau region column shows that different predetermined gas pressure values ​​correspond to different plateau regions, and the intersection of the plateau regions corresponding to 3.0atm to 4.0atm is 300V to 900V. Accordingly, the ideal plateau voltage range can be determined as 300V to 900V.

[0119] Please see Figure 8 The present invention also provides a system for determining the operating parameters of a nuclear reactor fission chamber detector, which may include a gas supply device 1, a neutron source 2, and a testing device 3.

[0120] The gas supply device 1 is used to provide working gas to the detector under test. Specifically, the gas supply device 1 can be an existing gas supply device capable of providing working gas (such as Ar) to the detector.

[0121] Neutron source 2 is used to provide the neutron beam for the test detector. Neutron source 2 can be an existing neutron source device, which can improve the fluence rate stability of the neutron beam.

[0122] Please see Figure 8 The testing device 3 includes an acquisition unit 31, a range determination unit 32, a voltage control unit 33, a gas supply control unit 34, a counting unit 35, and a parameter determination unit 36.

[0123] The acquisition unit 31 is used to acquire and display the output current relationship information of the detector under test. The output current relationship information may include an output current expression; the method for determining the output current expression is described above and will not be repeated here. Furthermore, the acquisition unit 31 may include a display.

[0124] The range determination unit 32 is used to determine the operating voltage test range of the detector under test based on the operation. Specifically, after obtaining the output current relationship information through the acquisition unit 31, the operator can set the operating voltage test range through the range determination unit 32. Furthermore, the range determination unit 32 may include a mouse and a keyboard.

[0125] The voltage control unit 33 is used to control the operation of the detector under test based on the operating voltage test range. The voltage control unit 33 can be an existing adjustable voltage source, capable of outputting voltages from 0V to 1000V according to control commands.

[0126] The gas supply control unit 34 is used to control the gas supply device 1 to sequentially provide the detector under test with working gas pressures of various predetermined gas pressure values.

[0127] In some embodiments, such as Figure 9 As shown, the gas supply control unit 34 may include a gas supply pipe 341, a valve 342, and a pressure gauge 343.

[0128] The gas supply pipe 341 is used for mechanical connection between the detector under test and the gas supply device 1.

[0129] Valve 342 is installed on the gas supply pipeline and is used to regulate the flow rate of working gas input to the detector under test. Valve 342 can be an existing ball valve.

[0130] Pressure gauge 343 is installed on the pipeline between the detector under test and valve 342. Pressure gauge 343 is used to measure the working gas pressure of the detector under test.

[0131] The counting unit 35 is used to acquire the output current of the detector under test when it is injected with a neutron beam and operates within the working voltage test range at each predetermined pressure value, and to determine the count rate data corresponding to each predetermined pressure value based on the output current.

[0132] In some embodiments, the counting unit 35 may include an amplifier, a single-channel analyzer, a scaler, and a counter.

[0133] The amplifier is used to amplify the output current of the detector under test, thereby improving the accuracy of the single-channel analyzer in identifying single-channel pulses and helping to improve counting accuracy.

[0134] A single-channel analyzer is used to identify single-channel pulses in the amplified output current that meet set conditions. It should be noted that the output current of the detector under test is a pulse current, which is superimposed with some noise. The function of the single-channel analyzer is to identify single-channel pulses within a specific amplitude range (i.e., those that meet set conditions). The number of these single-channel pulses that meet the set conditions can characterize the number of neutrons.

[0135] The calibrator is used to count single-channel pulses that meet set conditions and outputs the count information. The count information can characterize the number of neutrons detected by the detector under test.

[0136] The counter is used to determine the count rate data corresponding to each predetermined pressure value based on the counting information. Specifically, the counter is used to repeatedly determine the number of neutrons detected by the detector under test within a set time period based on the counting information, so as to obtain multiple neutron counts. The method for determining the count rate data is described above and will not be repeated here.

[0137] The parameter determination unit 36 ​​is used to determine the ideal operating parameters of the detector under test based on the count rate data. The method for determining the ideal operating parameters is described above and will not be repeated here.

[0138] To increase the concentration of the working gas introduced into the detector under test, in some embodiments, the nuclear reactor fission chamber detector operating parameter determination system may also include a gas extraction device and a heat preservation device.

[0139] The air extraction device is used to remove air from the detector under test before supplying working gas, ensuring that the air pressure in the detector does not exceed a set pressure value. Optionally, the set pressure value does not exceed 10 Pa. Ideally, the pressure in the detector under test after air extraction should be maintained within 10 Pa to 3 Pa.

[0140] The heat preservation device is used to maintain the detector under test within a set temperature range during evacuation. Optionally, the set temperature range is 118°C to 122°C, ideally around 120°C. It is easy to understand that heating the detector under test helps to minimize the gas pressure in the evacuation device before the working gas is injected.

[0141] In some embodiments, to simplify the determination process, when the working gas is supplied to the detector under test using the gas supply device 1, the working gas pressure can be charged to the maximum predetermined pressure value. In this way, in the subsequent process, the operator only needs to adjust the valve to make the working gas pressure decrease to the remaining predetermined pressure values ​​in sequence to carry out the corresponding test.

[0142] In some embodiments, the nuclear reactor fission chamber detector operating parameter determination system may further include a waveform recorder, which is used to record the output current waveform of the detector under test, so that staff can easily review and observe the process parameters.

[0143] Understandably, the technical solution of the present invention can help staff determine the ideal operating parameters of the fission chamber detector, increase the probability of fission fragments ionizing in the fission chamber detector, and allow fragment energy to be fully deposited in the sensitive area. This can increase the amplitude of the output current, improve the signal-to-noise ratio of the detector, help improve the sensitivity and detection efficiency of the detector, and make the detector more capable of detecting fission fragments. This is of great significance for improving the working stability and reliability of the detector.

[0144] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0145] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0146] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0147] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A method for determining the operating parameters of a nuclear reactor fission chamber detector, characterized in that, include: Obtain the output current relationship information of the detector under test; Determining the operating voltage test range of the detector under test based on the output current relationship information includes: setting the lower limit voltage of the operating voltage test range to be greater than N. The voltage value, where N is a positive number; The working gas pressure of the detector under test is sequentially set to a variety of predetermined gas pressure values. After each setting of the working gas pressure, the detector under test is controlled to operate based on the working voltage test range. The count rate data corresponding to each predetermined gas pressure value is obtained and determined according to the output current of the detector under test when it is injected with a neutron beam. The setting range of the various predetermined gas pressure values ​​is 2.0 atm to 6.0 atm. The ideal operating parameters of the detector under test are determined based on the count rate data. The step of obtaining the output current relationship information of the detector under test includes: constructing a simulation model equivalent to the circuit structure of the detector under test, and analyzing the simulation model to determine the output current relationship information; the step of analyzing the simulation model to determine the output current relationship information includes: determining the output current expression of the detector under test based on the law of conservation of energy and the circuit structure of the simulation model. The output current expression is as follows: ； in, This represents the output current of the detector under test. This indicates the operating voltage of the detector under test. This represents the voltage at the second terminal of the equivalent module of the ionization chamber. This indicates that at time t, the j-th positive ion is located in the fission chamber. electric field strength, This represents the drift velocity of the j-th positive ion in the fission chamber at time t. This indicates that at time t, the k-th electron is located in the fission chamber. electric field strength, It represents the drift velocity of the k-th electron in the fission chamber at time t.

2. The method for determining the operating parameters of a nuclear reactor fission chamber detector according to claim 1, characterized in that, The steps of constructing a simulation model equivalent to the circuit structure of the detector under test include: Construct a circuit schematic equivalent to the circuit structure of the detector under test to obtain an initial circuit model; The circuit structure of the initial circuit model is simplified to obtain the simulation model; The simulation model includes a power supply, an ionization chamber equivalent module, a fission chamber equivalent capacitor (C1), a load equivalent resistance (R0), and a load equivalent capacitor (C2). The positive terminal of the power supply is connected to the first terminal of the ionization chamber equivalent module, and the second terminal of the ionization chamber equivalent module is connected to the negative terminal of the power supply via the load equivalent resistance (R0) and the load equivalent capacitor (C2).

3. The method for determining the operating parameters of a nuclear reactor fission chamber detector according to claim 1 or 2, characterized in that, The step of controlling the operation of the detector under test based on the operating voltage test range, and acquiring and determining the count rate data corresponding to each predetermined air pressure value based on the output current of the detector under test, includes: Multiple operating voltage points are determined based on the operating voltage test range; The operating voltage of the detector under test is sequentially set to the plurality of operating voltage points; After each operating voltage point is set, the following steps are performed: the neutron source is controlled to inject a neutron beam into the detector under test, and the output current of the detector under test is acquired multiple times within a set time period; the average count rate corresponding to the operating voltage point is calculated based on the multiple acquired output currents. Count rate data is generated based on the average count rate at various operating voltage points for each of the predetermined air pressure values.

4. The method for determining the operating parameters of a nuclear reactor fission chamber detector according to claim 3, characterized in that, The step of determining the ideal operating parameters of the detector under test based on the count rate data includes: Based on the count rate data, multiple plateau characteristic curves corresponding one-to-one with each of the predetermined air pressure values ​​are fitted; Determine the corresponding plateau characteristic data for each of the aforementioned plateau characteristic curves; The ideal plateau voltage range and ideal working gas pressure range of the detector under test are determined based on the plateau characteristic data.

5. The method for determining the operating parameters of a nuclear reactor fission chamber detector according to claim 4, characterized in that, The plateau characteristic data includes plateau voltage, plateau length, and plateau inclination; The step of determining the ideal plateau voltage range and ideal working gas pressure range of the detector under test based on the plateau characteristic data includes: For each of the plateau characteristic curves, the following is performed: determine whether the plateau length of the plateau characteristic curve is greater than a set plateau length; if so, mark the plateau characteristic curve. When at least one of the plateau characteristic curves is marked, for each marked plateau characteristic curve, the following is performed: determine whether the plateau slope of the plateau characteristic curve is less than the set plateau slope; if so, the plateau characteristic curve is defined as a qualified curve. The ideal working gas pressure range is determined based on the predetermined gas pressure values ​​of all the qualified curves. The ideal plateau voltage range is determined based on the plateau voltage of all the qualified curves.

6. A system for determining the operating parameters of a nuclear reactor fission chamber detector, characterized in that, include: Gas supply device, used to provide working gas to the detector under test; A neutron source, used to provide the detector under test with a neutron beam for the experiment; The testing device includes an acquisition unit, a range determination unit, a voltage control unit, a gas supply control unit, a counting unit, and a parameter determination unit; The acquisition unit is used to acquire the output current relationship information of the detector under test, including: constructing a simulation model equivalent to the circuit structure of the detector under test, and analyzing the simulation model to determine the output current relationship information; the step of analyzing the simulation model to determine the output current relationship information includes: determining the output current expression of the detector under test based on the law of conservation of energy and the circuit structure of the simulation model. The range determination unit is used to determine the operating voltage test range of the detector under test, including: setting the lower limit voltage of the operating voltage test range to be greater than N. The voltage value, where N is a positive number; The voltage control unit is used to control the operation of the detector under test based on the operating voltage test range; The gas supply control unit is used to control the gas supply device to sequentially provide the detector under test with a variety of predetermined gas pressure values; wherein, the range of the various predetermined gas pressure values ​​is from 2.0 atm to 6.0 atm; The counting unit is used to acquire the output current of the detector under test when it is injected with a neutron beam and operates based on the working voltage test range at each of the predetermined gas pressure values, and to determine the count rate data corresponding to each of the predetermined gas pressure values ​​based on the output current; The parameter determination unit is used to determine the ideal operating parameters of the detector under test based on the count rate data. The output current expression is as follows: ； in, This represents the output current of the detector under test. This indicates the operating voltage of the detector under test. This represents the voltage at the second terminal of the equivalent module of the ionization chamber. This indicates that at time t, the j-th positive ion is located in the fission chamber. electric field strength, This represents the drift velocity of the j-th positive ion in the fission chamber at time t. This indicates that at time t, the k-th electron is located in the fission chamber. electric field strength, It represents the drift velocity of the k-th electron in the fission chamber at time t.

7. The nuclear reactor fission chamber detector operating parameter determination system according to claim 6, characterized in that, The gas supply control unit includes: A gas supply pipe is used for mechanical connection between the detector under test and the gas supply device; A valve, installed on the gas supply pipeline, is used to regulate the flow rate of the working gas input to the detector under test; A pressure gauge is used to measure the working gas pressure of the detector under test.

8. The nuclear reactor fission chamber detector operating parameter determination system according to claim 6, characterized in that, The counting unit includes: An amplifier is used to amplify the output current of the detector under test. A single-channel analyzer is used to identify single-channel pulses in the amplified output current that meet set conditions; A scaler is used to count the single-channel pulses that meet the set conditions and output the count information; A counter is used to determine the count rate data corresponding to each of the predetermined air pressure values ​​based on the count information.

9. The nuclear reactor fission chamber detector operating parameter determination system according to any one of claims 6 to 8, characterized in that, The nuclear reactor fission chamber detector operating parameter determination system also includes: An air extraction device is used to extract the air from the detector under test before supplying working gas to the detector under test, and to ensure that the air pressure of the detector under test does not exceed a set pressure value. A heat preservation device is used to keep the detector under test within a set temperature range during evacuation.

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