Method and device for monitoring subcriticality during reactor physics startup process

Abstract

The application provides a method and a device for monitoring subcriticality in a reactor physics startup process, which can be applied to the field of reactor physics technology. The method comprises the following steps: obtaining neutron count change data of a reactor in a physics startup process; processing the neutron count change data based on an inverse kinetics method to obtain a first criticality; processing the neutron count change data based on an extrapolation method to obtain a second criticality; and determining the subcriticality of the reactor according to the first criticality and the second criticality. Embodiments of the application can calculate the subcriticality of the reactor in the physics startup process by combining the inverse kinetics method and the extrapolation method through neutron count change data. By combining the inverse kinetics method and the extrapolation method, the subcriticality of the reactor can be more accurately measured.

Description

Technical Field

[0001] This application relates to the field of nuclear reaction technology, and in particular to a method and device for monitoring the subcriticality of a reactor physical start-up process. Background Technology

[0002] During the physical startup of the reactor's initial fuel loading, a high-activity isotopic neutron source is used as a stable external neutron source to inject a neutron beam into the reactor, resulting in a stable neutron count within the reactor. Changes in the neutron count are detected by a neutron detector, enabling monitoring of the reactor's subcritical state.

[0003] In related technologies, critical loading is extrapolated by monitoring changes in loading and the reciprocal of the neutron count to monitor changes in reactor subcriticality. However, in the case of shallow subcriticality, which approaches but does not reach subcriticality, the extrapolated critical loading deviates from the actual critical loading due to the discrepancy between the actual loading state (reactivity value) and the theoretical loading state (reactivity value) of the reactor's peripheral components. This affects the accuracy of determining the subcritical state and also the transition to supercriticality. Summary of the Invention

[0004] In view of the above problems, this application provides a method and device for monitoring the subcriticality of the reactor physical start-up process.

[0005] According to a first aspect of this application, a method for monitoring subcriticality during reactor physical startup is provided, comprising:

[0006] Acquire neutron count changes during the physical startup process of the reactor;

[0007] The first criticality was obtained by processing neutron count variation data using the inverse dynamic method.

[0008] The second criticality was obtained by processing neutron count variation data using extrapolation; and

[0009] The subcriticality of the reactor is determined based on the first and second criticalities.

[0010] The second aspect of this application provides a monitoring device for the subcriticality of the reactor physical start-up process, comprising: a counter tube detector, disposed in front of the reactor, for detecting changes in the neutron count during the reactor physical start-up process and outputting a pulsed neutron signal;

[0011] The signal conditioner, connected at one end to the counter tube detector, is used to condition the pulsed neutron signal; and

[0012] The data processor, connected to the other end of the signal conditioner, is used to acquire neutron count change data of the reactor during the physical startup process based on the pulsed neutron signal, and to process the neutron count change data based on extrapolation and inverse dynamics to obtain the first criticality and the second criticality; and to obtain the subcriticality of the reactor based on the first criticality and the second criticality.

[0013] According to embodiments of this application, the apparatus further includes: a pulsed neutron tube for generating a pulsed neutron beam to drive a reactor in a subcritical state; and

[0014] The pulsed neutron tube control box, connected to the pulsed neutron tube, is used to control the pulsed neutron tube to generate a pulsed neutron beam and to control the intensity and pulse frequency of the pulsed neutron beam.

[0015] The embodiments of this application do not require improvements to the extrapolation method, nor do they require increasing the number of external neutron sources or neutron detectors. They only process neutron count changes within the same physical start-up process, combining the inverse dynamic method and the external source method to determine the reactor's subcriticality from both macroscopic and microscopic scales. Compared to using the extrapolation method or the inverse dynamic method alone, the embodiments of this application can reduce the error between the determined subcriticality and the actual subcriticality, improving the accuracy of subcriticality determination. Furthermore, the embodiments of this application also facilitate real-time monitoring of the subcriticality during fuel loading, thereby increasing safety during the physical start-up process. Attached Figure Description

[0016] The above-mentioned contents, other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0017] Figure 1 A flowchart is shown of a method for monitoring subcriticality during reactor physical startup according to an embodiment of this application.

[0018] Figure 2 A schematic diagram of a method for monitoring subcriticality during reactor physical startup according to a first embodiment of this application is shown.

[0019] Figure 3 A schematic diagram of a monitoring device for subcriticality during reactor physical startup according to an embodiment of this application is shown. Detailed Implementation

[0020] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0021] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0022] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0023] Extrapolating the critical load by monitoring changes in fuel loading and the reciprocal of the neutron count to monitor changes in reactor subcriticality is called the extrapolation method. During reactor fuel loading, the loading sequence is to load the central region fuel assemblies first, followed by the peripheral assemblies. This loading sequence leads to a discrepancy between the actual and theoretical values ​​of the peripheral assemblies, affecting the monitoring of subcriticality.

[0024] The embodiments of this application provide a novel method for monitoring reactor subcriticality during the physical start-up fueling process of a reactor.

[0025] Figure 1 A flowchart is shown of a method for monitoring subcriticality during reactor physical startup according to an embodiment of this application.

[0026] like Figure 1 As shown in the embodiments of this application, the method for monitoring the subcriticality of the reactor physical start-up process includes operations S110 to S140.

[0027] In operation S110, data on neutron count changes during the physical startup process of the reactor are acquired.

[0028] According to embodiments of this application, during the physical startup process of the reactor's initial fuel loading, a neutron beam is continuously injected into the reactor using an external neutron source, thereby maintaining a strong neutron count rate within the reactor. Then, a proportional counting neutron detector is used to monitor changes in the neutron count within the reactor in real time.

[0029] While the proportional counting neutron detector monitors the changes in the neutron count in the reactor in real time, the acquisition card is used to acquire the changes in the neutron count in the reactor at high speed, so that the subcriticality of the reactor can be determined by extrapolation and inverse dynamic methods.

[0030] In operation S120, the neutron count change data is processed based on the inverse dynamic method to obtain the first criticality.

[0031] According to an embodiment of this application, the inverse dynamic method is used to determine the reactivity of a reactor based on neutron count change data, and then, based on the determined reactivity, to determine the subcriticality of the reactor, i.e., the first criticality.

[0032] In operation S130, the neutron count change data is processed based on extrapolation to obtain the second criticality.

[0033] According to an embodiment of this application, the extrapolation method is used to determine the extrapolated critical load based on neutron count change data, and then to determine the subcriticality of the reactor, i.e., the second criticality, based on the extrapolated critical load and the actual load.

[0034] In operation S140, the subcriticality of the reactor is determined based on the first criticality and the second criticality.

[0035] Since both the inverse dynamic method and the extrapolation method are based on neutron counts provided by an external neutron source to determine the subcriticality of the reactor, when monitoring the subcriticality of the reactor during the physical startup process, the inverse dynamic method and the extrapolation method can be combined using neutron count change data during the monitoring process to more accurately determine the subcriticality of the reactor.

[0036] According to embodiments of this application, an external neutron source can continuously generate a neutron beam and inject the generated neutron beam into a reactor. However, during the process of injecting the neutron beam into the reactor, the neutron count in the reactor changes in stages and fluctuates.

[0037] Specifically, since neutron beam injection requires a process, the neutron count changes in a stepwise manner on a macroscopic scale (over a long time); on a microscopic scale (over a short time), the neutron count fluctuates around a certain value.

[0038] For example, within a 2-3 second time interval, the neutron count changes from one relatively stable value to another. Within a time interval on the order of tens of milliseconds, the neutron count fluctuates around a stable value.

[0039] According to embodiments of this application, based on the principles of inverse dynamics and extrapolation, neutron count changes within the same physical startup process are processed at both the microscopic and macroscopic scales to obtain the first criticality and the second criticality; the subcriticality of the reactor is then determined based on the first and second criticalities. Since embodiments of this application do not require improvements to the extrapolation method, nor do they require increasing the number of external neutron sources or neutron detectors, the subcriticality of the reactor is determined jointly at both the macroscopic and microscopic scales simply by processing neutron count changes within the same physical startup process and combining the inverse dynamics and external source methods.

[0040] Compared to using extrapolation or inverse dynamics alone, the embodiments of this application can reduce the error between the determined subcriticality and the actual subcriticality, improving the accuracy of determining the subcriticality; it also helps to monitor the subcriticality in real time during the loading process, thereby increasing the safety of the physical start-up process.

[0041] According to embodiments of this application, the reactivity of the reactor is calculated based on the inverse dynamic method and neutron count variation data. The reactor's first criticality can then be determined from the reactivity.

[0042] Specifically, the formula used to determine the reactor reactivity based on the inverse dynamic method is:

[0043]

[0044] Where ρ represents reactivity, β represents the delayed neutron fraction, Λ represents the neutron generation time, and β i λ represents the share of delayed neutron emission in the i-th group. i Let represent the decay constant of the i-th delayed neutron precursor nucleus, n(t) represent the neutron count acquired at time t, and S represent the external neutron source with an initial time of t0.

[0045] When calculating reactivity, if the contribution of a changing external neutron source to reactor neutrons is much greater than the contribution of other neutron sources to reactor neutrons in the S term of Formula 1, S can be set to 0.

[0046] Since the collected neutron count change data can reflect the changes in neutron count at the microscopic scale, the reactor reactivity can be calculated by substituting the neutron count change data into the above formula (1), or by substituting the neutron count change data into the formula after transforming formula (1). In order to facilitate the calculation, formula (1) can be transformed at the mathematical level.

[0047] The first criticality is determined based on the reactor's reactivity. After determining the reactor's reactivity using the inverse dynamic method, the first criticality can be determined based on the correspondence between reactivity and subcriticality.

[0048] According to an embodiment of this application, processing neutron count change data based on extrapolation to obtain a second criticality includes: processing neutron count change data according to a predetermined time interval to obtain extrapolated calculation data; and obtaining a second criticality based on the extrapolated calculation data.

[0049] According to an embodiment of this application, since neutron count change data can reflect the changes in neutron count at the microscale, the microscale neutron count change data is processed into macroscale extrapolation calculation data before the extrapolation method is used to calculate the second criticality.

[0050] Specifically, based on the duration of a predetermined time interval, the stable value of the neutron count within the predetermined time interval is calculated according to the neutron count change data, resulting in extrapolated calculation data of stepwise changes based on the duration of the predetermined time interval.

[0051] Among them, neutron count variation data represents the microscopic changes in the neutron count. At the microscopic scale, the measured neutron count is a continuous series of pulse peaks. Extrapolated calculation data can represent the macroscopic changes in the neutron count, where the duration of a predetermined time interval is greater than or equal to the duration of one pulse in the neutron count variation data.

[0052] According to an embodiment of this application, processing neutron count change data according to a predetermined time interval to obtain extrapolated calculation data includes: dividing the neutron count change data into multiple time periods, the duration of each time period being greater than or equal to the duration of the predetermined time interval; calculating the average neutron count within each of the multiple time periods to obtain the average neutron count corresponding to the multiple time periods, and the extrapolated calculation data including the average neutron count.

[0053] For example, given a set of 20-second neutron count change data, the predetermined time interval is 2 seconds. Starting from 0, the 20-second neutron count change data is divided into 10 time intervals of 2 seconds each.

[0054] According to embodiments of this disclosure, when dividing neutron count change data into multiple time periods, the durations of the multiple time periods may not be equal.

[0055] For example, taking the neutron count change data over 20 seconds as an example, with a predetermined time interval of 2 seconds, starting from 0, the neutron count change data over 20 seconds is divided into 5 time intervals of 2 seconds, 4 seconds, 6 seconds, 2 seconds, and 6 seconds respectively.

[0056] For each time period, the average neutron count over the duration of that time period is calculated based on the neutron count change data within that time period. This yields the average neutron count for multiple time periods, and the obtained average neutron count is used as extrapolation data.

[0057] According to embodiments of this application, in the process of determining extrapolated calculation data based on neutron count change data, the start times of multiple time periods can be determined according to actual circumstances. For example, the moment when a significant change in the neutron count occurs can be taken as the start time of each time period.

[0058] The embodiments of this application process neutron count variation data by using predetermined time intervals to convert microscopic data into macroscopic data, thereby realizing the calculation of subcriticality using extrapolation to process neutron count variation data. By processing neutron count variation data only considering the characteristics of macroscopic and microscopic changes in neutron count, microscopic data can be converted into macroscopic data without the need for other detectors. Combining extrapolation and inverse dynamics simplifies the integration cost.

[0059] According to an embodiment of this application, after determining the extrapolated calculation data of the reactor, the second criticality of the reactor is determined based on the fuel loading status in the reactor and the extrapolated calculation data.

[0060] According to an embodiment of this application, an extrapolated critical load corresponding to multiple time periods can be calculated based on the average neutron count and the loading status; the extrapolated critical load is compared with the actual load corresponding to the multiple time periods to obtain the loading difference required to reach the extrapolated critical load; then, using the theoretical loading coefficient corresponding to the theoretical critical load and the above loading difference, a second criticality corresponding to the multiple time periods can be obtained.

[0061] The theoretical critical load is a standard critical load obtained through simulation using computer or other equipment. The theoretical load coefficient is used to characterize the reactivity value corresponding to a unit load.

[0062] In calculating the second criticality of the current state, the current load corresponding to multiple time periods is compared with the extrapolated critical load to obtain the load difference that will be needed to reach the criticality later. Then, the theoretical load coefficient calculated by theory is used to obtain the second criticality corresponding to multiple time periods.

[0063] For example, time period A starts at time T1 and ends at time T2, with time Ti falling within time period A. Based on the average neutron count and loading status of time period A, the extrapolated critical loading corresponding to the end time of time period A, i.e., time T2, is calculated. For time Ti within time period A, the current loading at time Ti is compared with the extrapolated critical loading corresponding to time period A to obtain the loading difference. For example, with 3 fewer fuel rods, the loading difference can be -3. The theoretical loading factor is 10 pcm, thus the second criticality at time Ti calculated is -30 pcm.

[0064] Specifically, the formula for calculating the critical load of the reactor is:

[0065]

[0066] Where M1 and M2 represent the fuel loading or control rod positions corresponding to two different loading states, M c This indicates the extrapolated critical load. N1 is the neutron count corresponding to M1, which is the average neutron count corresponding to M1 calculated based on the neutron count change data. N2 is the neutron count corresponding to M2, which is the average neutron count corresponding to M2 calculated based on the neutron count change data.

[0067] According to embodiments of this application, the extrapolation method can determine the extrapolated critical load from one loading state to another. Based on the extrapolation calculation data and the loading state, the extrapolated critical load corresponding to multiple time periods can be determined.

[0068] After determining the extrapolated critical load, the second criticality of the current loading state can be obtained by using the load difference between the current load and the extrapolated critical load and the theoretical load coefficient near the theoretical critical load.

[0069] The embodiments of this application can calculate the second criticality using data collected at a microscopic timescale without the need for other neutron measurement data. Without adding measurement steps, this helps to determine the subcriticality of the reactor based on the first and second criticalities obtained by extrapolation and inverse dynamics.

[0070] According to the embodiments of this application, after determining the first criticality and the second criticality using the inverse dynamic method and the extrapolation method respectively, if both the first criticality and the second criticality meet the preset conditions, the first criticality or the second criticality is taken as the subcriticality of the reactor during the physical startup process.

[0071] For example, if the first criticality and the second criticality are both within the same preset range, the first criticality or the second criticality can be used as the subcriticality of the reactor during the physical startup process.

[0072] According to the embodiments of this application, after determining the first criticality and the second criticality using the inverse dynamic method and the extrapolation method respectively, the first criticality of the same state can be adjusted based on the second criticality to obtain the subcriticality of the reactor during the physical startup process.

[0073] For example, the trend of the subcriticality under the current loading state is determined based on the second criticality determined by extrapolation. The trend can be too small or too large. Then, the first criticality determined by the inverse dynamic method is adjusted based on the determined trend to obtain the subcriticality of the reactor during the physical startup process.

[0074] Figure 2 The figure shows a schematic diagram of a method for monitoring the subcriticality during the reactor physical startup process according to the first embodiment of the present application.

[0075] As Figure 2 shown in the figure, the specific information monitored in states 1, 2, and 3 during the physical startup process is represented. Among them, M1, M2, and M3 can represent the control rod positions or fuel loadings of the reactor corresponding to the three states, and M1 < M2 < M3.

[0076] States 1, 2, and 3 respectively correspond to three time periods on the macroscopic scale, and the average neutron counts within these three time periods are N1, N2, and N3, where N1 < N2 < N3. It should be noted that as time increases, the total number of neutron counts in the reactor also gradually increases, and the calculated average neutron count is actually the relatively stable value of the total neutron count within that time period, that is, N1, N2, and N3 are the total neutron counts within states 1, 2, and 3 respectively.

[0077] n1, n2, and n3 are respectively the microscopic changes in neutron counts within the time periods of states 1, 2, and 3. n1, n2, and n3 all include multiple pulse peaks. Among them, n1 < n2 < n3, indicating that the overall height of the counting platforms on the microscopic time scale of states 1, 2, and 3 shows an upward trend.

[0078] A, B, and C represent the reactivity changes corresponding to states 1, 2, and 3 respectively calculated using the inverse dynamics method. Among them, A < B < C, indicating that the overall height of the reactivity platforms on the microscopic time scale of states 1, 2, and 3 shows an upward trend.

[0079] As Figure 2 shown, after the reactor undergoes refueling or control rod lifting operations, three different states are presented. After the macroscopic scale neutron counts corresponding to the three states are stabilized, the recorded macroscopic scale neutron counts are N1, N2, and N3 respectively. Using "M1, M2, N1, N2", the extrapolated critical loading or critical rod position of state 2 can be obtained based on the extrapolation method. After obtaining the unit loading value or theoretical rod value through theoretical calculation, the reactivity value corresponding to the loading difference between the current loading and the extrapolated critical loading can be determined based on the unit loading value or theoretical rod value to determine the second criticality ρ1 of the current reactor in state 2. Similarly, using "M2, M3, N2, N3", the second criticality ρ2 of the current reactor in state 3 can be further determined.

[0080] While recording the macroscopic neutron counts N1, N2, and N3, microscopic neutron count variation data n1, n2, and n3 were also obtained. The neutron count variation data n1, n2, and n3 were processed using the inverse dynamic method to obtain the microscopic reactivity variations A, B, and C; then, based on the reactivity variations A, B, and C, the first criticality corresponding to states 1, 2, and 3 was obtained.

[0081] Specifically, at a fixed pulse frequency, the bottom plateaus of the changes in A, B, and C correspond to the reactivity ρ0, ρ1′, and ρ2′ of states 1, 2, and 3, respectively, representing the reactor's first criticality in states 1, 2, and 3. By comparing ρ1′ with ρ1 and ρ2′ with ρ2, the reactor's subcriticality in states 2 and 3 can be determined.

[0082] Therefore, the embodiments of this application combine extrapolation and inverse dynamic methods by utilizing an external neutron source, providing a new method for monitoring reactor reactivity and reactor subcriticality. This method can not only be used for rapid reactor startup and deployment, increasing safety during the physical startup process, but also provides a method for real-time online monitoring of Accelerator Driven Subcritical Systems (ADS).

[0083] According to an embodiment of this application, during the physical startup of the reactor, a pulsed neutron beam is generated by a pulsed neutron tube to drive the reactor in a subcritical state.

[0084] Specifically, a stable pulsed neutron beam is generated by a pulsed neutron tube, and this pulsed neutron beam is used as an external neutron source and injected into the reactor core to drive the reactor in a subcritical state.

[0085] By using pulsed neutron beams, it can be ensured that the changes in neutron count data on a macroscopic scale follow a step-like trend, so that extrapolated calculation data can be determined based on the changes in neutron count data.

[0086] According to an embodiment of this application, during the physical startup of the reactor, the intensity of the pulsed neutron beam is controlled within a first preset fluctuation range, and the pulse frequency of the pulsed neutron beam is controlled to a preset value, so as to obtain neutron count change data.

[0087] According to the embodiments of this application, by controlling the intensity of the pulsed neutron beam within a first preset fluctuation range and controlling the pulse frequency within a preset value, the stability of the pulsed neutron beam can be guaranteed, and the influence of external factors on the accuracy of reactor subcriticality monitoring can be minimized.

[0088] In addition, the extrapolated calculation data obtained at the macro scale can be corrected by modifying the first preset fluctuation range and preset value.

[0089] According to an embodiment of this application, during the physical startup of the reactor, the pulsed neutron tube is controlled to DC mode, and the intensity of the pulsed neutron beam is varied within a second preset fluctuation range by controlling the neutron tube to obtain neutron count change data.

[0090] According to embodiments of this application, the pulsed neutron beam can be controlled by adjusting the pulse frequency in real time. Alternatively, the pulsed neutron tube can be set to DC mode, and the intensity of the pulsed neutron beam can be varied within a second preset fluctuation range at the microscale to continuously provide an external neutron source. In the case of using DC mode, reactive measurements can also be performed using a modified neutron counting method or a modified inverse dynamic method.

[0091] Figure 3 A schematic diagram of a monitoring device for subcriticality during reactor physical startup according to an embodiment of this application is shown.

[0092] The monitoring device for subcriticality during reactor physical startup includes a counter tube detector, a signal conditioner, and a data processor. The counter tube detector is used to detect changes in the neutron count during reactor physical startup and outputs a pulsed neutron signal.

[0093] like Figure 3 As shown, the counter tube detector can be a high-sensitivity proportional counter tube detector, placed on one side of the reactor, such as directly in front, so as to obtain a large neutron count at the microscale.

[0094] The signal conditioner is connected at one end to a high-sensitivity proportional counter tube detector and is used to condition the pulsed neutron signal.

[0095] The data processor, connected to the other end of the signal conditioner, is used to acquire neutron count change data of the reactor during the physical startup process based on the pulsed neutron signal, and to process the neutron count change data based on extrapolation and inverse dynamics to obtain the first criticality and the second criticality; and to obtain the subcriticality of the reactor based on the first criticality and the second criticality.

[0096] According to an embodiment of this application, the monitoring device for the subcriticality of the reactor physical start-up process further includes: a pulsed neutron tube and a pulsed neutron tube control box.

[0097] A pulsed neutron tube is used to generate a pulsed neutron beam to drive a reactor in a subcritical state.

[0098] According to embodiments of this disclosure, the position and sensitivity of the counter tube detector can be adjusted according to actual conditions, and the activity of the neutron source can also be adjusted according to actual conditions.

[0099] like Figure 3 As shown, the pulsed neutron tube control box is connected to the pulsed neutron tube and is used to control the pulsed neutron tube to generate a pulsed neutron beam, and to control the intensity and pulse frequency of the pulsed neutron beam.

[0100] According to an embodiment of this application, the pulsed neutron tube control box can control the pulsed neutron tube to output a pulsed neutron beam via a square wave, wherein the duty cycle of the square wave can be determined according to the actual situation.

[0101] According to embodiments of this application, the pulsed neutron tube control box can also control the pulsed neutron tube to output a pulsed neutron beam using other pulsed waves.

[0102] Due to the high cost and stringent transportation and storage conditions of high-activity isotope neutron sources, reactor monitoring combining inverse dynamics and extrapolation methods cannot be achieved in scenarios where the conditions for using high-activity isotope neutron sources are not available.

[0103] Therefore, the embodiments of this application provide an external neutron source through a pulsed neutron tube, which partially solves the problem of harsh transportation conditions and storage environment for external neutron sources, and realizes the monitoring of reactor subcriticality using inverse dynamics and extrapolation methods.

[0104] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0105] Those skilled in the art will understand that the features described in the various embodiments and / or claims of this application can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments and / or claims of this application can be combined or combined in various ways without departing from the spirit and teachings of this application. All such combinations and / or combinations fall within the scope of this application.

[0106] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for monitoring subcriticality during reactor physical start-up, characterized in that, The method includes: Acquire neutron count changes during the physical startup process of the reactor; The first criticality is obtained by processing the neutron count change data using the inverse dynamic method. The second criticality is obtained by processing the neutron count change data using extrapolation; and The subcriticality of the reactor is determined based on the first criticality and the second criticality. During the physical startup of the reactor, a pulsed neutron beam is generated by a pulsed neutron tube to drive the reactor in a subcritical state. The intensity of the pulsed neutron beam is controlled within a first preset fluctuation range, and the pulse frequency of the pulsed neutron beam is controlled to a preset value, so as to obtain the neutron count change data; The pulsed neutron beam is controlled by adjusting the pulse frequency of the pulsed neutron tube in real time. Determining the subcriticality of the reactor based on the first criticality and the second criticality includes: adjusting the first criticality of the same state based on the second criticality to obtain the subcriticality of the reactor during the physical startup process. The step of adjusting the first criticality of the same state based on the second criticality to obtain the subcriticality of the reactor during the physical start-up process includes: Based on the determined second criticality, the trend of the subcriticality of the current loading state is determined, and the trend is either too small or too large; based on the determined trend, the first criticality is adjusted to obtain the subcriticality of the reactor during the physical startup process.

2. The method according to claim 1, characterized in that, The process of processing the neutron count change data based on the inverse dynamic method to obtain the first criticality includes: Based on the inverse dynamic method, the reactivity of the reactor is calculated according to the neutron count change data; and The first criticality of the reactor is obtained based on the reactivity.

3. The method according to claim 1, characterized in that, The process of processing the neutron count change data based on extrapolation to obtain the second criticality includes: The neutron count change data is processed according to a predetermined time interval to obtain extrapolated calculation data, wherein the duration of the predetermined time interval is greater than or equal to the duration of a pulse in the neutron count change data; and The second criticality is obtained based on the extrapolated calculation data.

4. The method according to claim 3, characterized in that, The step of processing the neutron count change data according to a predetermined time interval to obtain extrapolated calculation data includes: The neutron count change data is divided into multiple time periods, each time period having a duration greater than or equal to the duration of the predetermined time interval; and The average neutron count within each of the multiple time periods is calculated to obtain the average neutron count corresponding to the multiple time periods. The extrapolated calculation data includes the average neutron count.

5. The method according to claim 4, characterized in that, The extrapolated calculation data also includes the loading status corresponding to the multiple time periods; obtaining the second criticality based on the extrapolated calculation data includes: The second criticality is calculated based on the average neutron count and the loading state.

6. The method according to claim 5, characterized in that, The calculation of the subcriticality of the reactor based on the average neutron count and the loading state includes: Based on the average neutron count and loading status, calculate the extrapolated critical loading corresponding to the multiple time periods; and The extrapolated critical load is compared with the actual load corresponding to the multiple time periods to obtain the load difference required to reach the extrapolated critical load. By using the theoretical loading coefficient corresponding to the theoretical critical loading and the loading difference, a second criticality corresponding to the multiple time periods is obtained. The theoretical loading coefficient is used to characterize the reactivity value corresponding to a unit loading.

7. A device for monitoring the subcriticality of a reactor's physical start-up process, characterized in that, The device includes: A counter tube detector, placed on one side of the reactor, is used to detect changes in the neutron count during the physical startup process of the reactor and output a pulsed neutron signal; A signal conditioner, one end of which is connected to the counter tube detector, is used to condition the pulsed neutron signal; and A data processor, connected to the other end of the signal conditioner, is used to acquire neutron count change data of the reactor during the physical startup process based on the pulsed neutron signal, and to process the neutron count change data based on the inverse dynamic method to obtain the first criticality, and to process the neutron count change data based on the extrapolation method to obtain the second criticality; and to obtain the subcriticality of the reactor based on the first criticality and the second criticality. The step of obtaining the subcriticality of the reactor based on the first criticality and the second criticality includes: adjusting the first criticality of the same state based on the second criticality to obtain the subcriticality of the reactor during the physical startup process. The step of adjusting the first criticality of the same state based on the second criticality to obtain the subcriticality of the reactor during the physical start-up process includes: Based on the determined second criticality, the trend of the subcriticality of the current loading state is determined, and the trend is either too small or too large; based on the determined trend, the first criticality is adjusted to obtain the subcriticality of the reactor during the physical start-up process. A pulsed neutron tube is used to generate a pulsed neutron beam to drive a reactor in a subcritical state; and A pulsed neutron tube control box, connected to the pulsed neutron tube, is used to control the pulsed neutron tube to generate a pulsed neutron beam and to control the intensity and pulse frequency of the pulsed neutron beam. During the physical startup of the reactor, the intensity of the pulsed neutron beam is controlled within a first preset fluctuation range, and the pulse frequency of the pulsed neutron beam is controlled to a preset value, so as to obtain the neutron count change data. The pulsed neutron beam is controlled by adjusting the pulse frequency of the pulsed neutron tube in real time.

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