Method, system, device and medium for criticality control of a pressurized water reactor

Abstract

This application discloses a method, system, equipment, and medium for achieving criticality control in a pressurized water reactor (PWR) of a nuclear power plant. The method includes: completely removing the shutdown rods and power control rods from the reactor core, and partially removing the temperature control rods; determining a first multiple switching condition, a second multiple switching condition, and a multiple dilution stop condition; diluting the primary loop system at a first flow rate and monitoring multiple first parameters; when any first parameter satisfies the first multiple switching condition, diluting the primary loop system at a second flow rate and monitoring multiple second parameters; when any second parameter satisfies the second multiple switching condition, diluting the primary loop system at a third flow rate and monitoring multiple third parameters; and stopping dilution when any third parameter satisfies the multiple dilution stop condition, and maintaining the PWR in a critical state by adjusting the temperature control rods. Implementing the method of this application can improve the safety and efficiency of criticality operation.

Description

Technical Field

[0001] This application relates to the field of nuclear power technology, and in particular to criticality control methods, systems, equipment and media for pressurized water reactors in nuclear power plants. Background Technology

[0002] Reaching criticality is a crucial step in restarting a nuclear power plant after initial fuel loading, refueling overhaul, or long-term shutdown. The control and efficiency of the criticality process directly affect the safety and economy of the nuclear power plant. Its core objective is to ensure unit safety while precisely controlling the reactor's reactivity to smoothly and efficiently reach primary criticality from a subcritical state.

[0003] In pressurized water reactor nuclear power plants, reactivity control is primarily achieved by adjusting the position of control rods (including shutdown rods, temperature control rods, and power control rods) and altering the concentration of boric acid, a soluble neutron-absorbing poison, in the coolant. Dilution, achieved by injecting demineralized water into the primary coolant system to reduce boron concentration, increases core reactivity. During core loading, to ensure sufficient subcriticality, the boric acid concentration in the coolant is high. Therefore, significant dilution is required to gradually increase core reactivity as the reactor approaches criticality, eventually bringing it closer to criticality. Finally, raising the control rod positions or continuing dilution brings the reactor to criticality.

[0004] Currently, pressurized water reactors typically employ two techniques for initial criticality assessment: control rod lifting and dilution. The control rod lifting approach requires raising all control rods to a target intermediate position, followed by dilution at a conservative flow rate. This involves repeatedly lifting and inserting control rods during dilution to determine criticality, resulting in complex and inefficient operations. The dilution approach requires lifting the deactivated control rods before dilution, followed by a first-stage dilution. After the first stage, a second stage of dilution is performed after uniform dilution. This also results in low efficiency in achieving criticality. Furthermore, both existing techniques use the inverse count rate (ICRR) or boron concentration as the criticality assessment criterion, relying on a single criterion. Failure of equipment related to this criterion can severely compromise the safety of reaching criticality.

[0005] There is an urgent need for a method to improve the safety and efficiency of criticality-reaching operations. Summary of the Invention

[0006] This application provides a method, system, equipment, and medium for controlling the criticality of a pressurized water reactor in a nuclear power plant, which can improve the safety and efficiency of criticality operation.

[0007] In a first aspect, embodiments of this application provide a method for achieving criticality control in a pressurized water reactor of a nuclear power plant, comprising: Completely remove the shutdown rods and power control rods of the pressurized water reactor from the core, and partially remove the temperature regulating rods from the core. The first multiple switching condition, the second multiple switching condition, and the multiple dilution stop condition are determined based on the boron concentration of the primary loop system and the preset count rate threshold. The primary loop system is diluted with a first flow rate, and multiple different types of first parameters are monitored; When any of the first parameters satisfies the first multiple switching condition, the first loop system is diluted with a second flow rate less than the first flow rate, and multiple different types of second parameters are monitored. When any of the second parameters satisfies the second multiple switching condition, the first loop system is diluted with a third flow rate less than the second flow rate, and multiple different types of third parameters are monitored. When any of the third parameters meets the multiple dilution stop condition, the dilution of the primary loop system is stopped, and the pressurized water reactor is maintained in a critical state by adjusting the temperature regulating rod.

[0008] In some embodiments, the boron concentration includes the current boron concentration and the theoretical critical boron concentration, and determining the first multiple switching condition, the second multiple switching condition, and the multiple dilution stop condition based on the boron concentration of the primary loop system and a preset count rate threshold includes: The maximum dilution water volume is determined based on the current boron concentration, the theoretical critical boron concentration, and the total volume of the primary loop system. The first boron concentration threshold and the second boron concentration threshold are determined based on the theoretical critical boron concentration, the preset first concentration buoyancy, and the preset second concentration buoyancy, respectively. The first extrapolated residual water threshold and the second extrapolated residual water threshold are determined based on the theoretical critical boron concentration, the total volume, the first boron concentration threshold, and the second boron concentration threshold, respectively. The first multiple switching condition, the second multiple switching condition, and the multiple dilution stop condition are determined based on the countdown rate threshold, the maximum dilution water volume, the first boron concentration threshold, the second boron concentration threshold, the first extrapolated remaining water volume threshold, and the second extrapolated remaining water volume threshold.

[0009] In some embodiments, the countdown rate threshold includes a first countdown rate threshold and a second countdown rate threshold. Determining the first multiple switching condition, the second multiple switching condition, and the multiple dilution stop condition based on the countdown rate threshold, the maximum dilution water volume, the first boron concentration threshold, the second boron concentration threshold, the first extrapolated remaining water volume threshold, and the second extrapolated remaining water volume threshold includes: The first multiple switching condition is determined based on the first boron concentration threshold, the first extrapolated remaining water threshold, and the preset first count rate threshold. The second multiple switching condition is determined based on the second boron concentration threshold, the second extrapolated remaining water threshold, and the preset second count rate threshold. The multiple dilution stop condition is determined based on the preset critical switching condition, the maximum dilution water volume, and the preset relationship between the current cumulative dilution water volume and the extrapolated total water volume.

[0010] In some embodiments, determining the first extrapolated residual water threshold and the second extrapolated residual water threshold based on the theoretical critical boron concentration, the total volume, the first boron concentration threshold, and the second boron concentration threshold, respectively, includes: Based on the total volume, determine the first remaining water volume required to dilute the boron concentration in the primary loop system from the first boron concentration threshold to the theoretical critical boron concentration, and determine the first extrapolated remaining water volume threshold based on the first remaining water volume. Based on the total volume, determine the second amount of residual water required to dilute the boron concentration in the primary loop system from the second boron concentration threshold to the theoretical critical boron concentration, and determine the second extrapolated residual water threshold based on the second amount of residual water.

[0011] In some embodiments, determining the first extrapolated remaining water volume threshold based on the first remaining water volume includes: The first extrapolated remaining water volume initial threshold is determined based on the first remaining water volume and the preset first multiple, wherein the first multiple is greater than or equal to 1; Determine whether the initial threshold of the first extrapolated remaining water volume is greater than or equal to the first water volume, where the first water volume is the water volume obtained by diluting the second flow rate for a first preset time. If it is greater than or equal to the first water volume, then the first extrapolated remaining water volume initial threshold is determined as the first extrapolated remaining water volume threshold. If it is less than the first water volume, then the first water volume is determined as the first extrapolated remaining water volume threshold.

[0012] In some embodiments, determining the second extrapolated remaining water volume threshold based on the second remaining water volume includes: The second extrapolated remaining water volume initial threshold is determined based on the second remaining water volume and a preset second multiple, wherein the second multiple is greater than or equal to 1; Determine whether the initial threshold of the second extrapolated remaining water volume is greater than or equal to the second water volume, where the second water volume is the water volume obtained by diluting the second preset time with the third flow rate; If it is greater than or equal to the second water volume, then the initial threshold of the second extrapolated remaining water volume is determined as the second extrapolated remaining water volume threshold. If it is less than the second water volume, then the second water volume is determined as the second extrapolated remaining water volume threshold.

[0013] In some embodiments, after completely removing the shutdown rods and power control rods of the pressurized water reactor from the core and partially removing the temperature regulating rods from the core, the method further includes: A reference count rate is obtained, which is the source range neutron count rate obtained before dilution of the primary loop system, or the source range neutron count rate obtained after dilution to a preset empirical boron concentration.

[0014] In some embodiments, the first parameter includes a first current countdown rate, a first current boron concentration, and a first current extrapolated residual water volume; the monitoring of multiple different types of first parameters includes: The first current count rate is determined based on the baseline count rate and the current source range neutron count rate of the pressurized water reactor; The boron concentration of the primary loop system is detected to obtain the first current boron concentration; The first current extrapolated remaining water volume is determined based on the first current countdown rate, the countdown rate trend, and the diluted water volume.

[0015] In some embodiments, the first multiple switching conditions include a first switching sub-condition, a second switching sub-condition, and a third switching sub-condition, wherein: The first switching sub-condition is that the first current countdown rate is less than or equal to the first countdown rate threshold; The second switching sub-condition is that the first current boron concentration is less than or equal to the first boron concentration threshold; The third switching sub-condition is that the first current extrapolated remaining water volume is less than or equal to the first extrapolated remaining water volume threshold.

[0016] In some embodiments, the second parameter includes a second current countdown rate, a second current boron concentration, and a second current extrapolated residual water volume. The monitoring of multiple different types of second parameters includes: The second current count rate is determined based on the baseline count rate and the current source range neutron count rate of the pressurized water reactor; The boron concentration of the primary loop system is detected to obtain the second current boron concentration; The second current extrapolated remaining water volume is determined based on the second current countdown rate, the countdown rate trend, and the diluted water volume.

[0017] In some embodiments, the second multiple switching conditions include a fourth switching sub-condition, a fifth switching sub-condition, and a sixth switching sub-condition, wherein: The fourth switching sub-condition is that the second current countdown rate is less than or equal to the second countdown rate threshold; The fifth switching sub-condition is that the second current boron concentration is less than or equal to the second boron concentration threshold. The sixth switching sub-condition is that the second current extrapolated remaining water volume is less than or equal to the second extrapolated remaining water volume threshold.

[0018] In some embodiments, the third parameter includes a threshold value and the current cumulative dilution water volume, the threshold value including at least one of the source range neutron count rate doubling time, the intermediate range output current doubling time, the current reactivity of the core, and the current output current of the intermediate range detector of the pressurized water reactor.

[0019] In some embodiments, the multiple dilution stop conditions include a critical switching condition, a dilution water volume switching condition, and an extrapolated water volume switching condition, wherein: The critical switching condition includes at least one of the following: The doubling time of the quantum count rate in the source range or the doubling time of the output current in the intermediate range is less than or equal to 200s; The current reactivity of the reactor core is 30 pcm; The current output current of the intermediate range detector of the pressurized water reactor reaches the current corresponding to 1E-3%FP; The condition for switching the dilution water volume is that the current cumulative dilution water volume is greater than the maximum dilution water volume; The extrapolation water volume switching condition is that the current cumulative dilution water volume is greater than or equal to the extrapolated total water volume, and the extrapolated total water volume is less than the maximum dilution water volume.

[0020] In some embodiments, maintaining the pressurized water reactor in a critical state by adjusting the temperature regulating rod includes: When the core reactivity is positive, the temperature regulating rod is inserted to introduce negative reactivity; When the core reactivity is negative, the temperature regulating rod is raised to introduce positive reactivity.

[0021] Secondly, embodiments of this application also provide a criticality control system for a pressurized water reactor in a nuclear power plant, comprising: The rod lifting module is used to completely remove the shutdown rod and power control rod of the pressurized water reactor from the reactor core, and to partially remove the temperature regulating rod from the reactor core. The condition determination module is used to determine the first multiple switching condition, the second multiple switching condition, and the multiple dilution stop condition based on the boron concentration of the primary loop system and the preset count rate threshold. A dilution module for diluting the primary loop system at a first flow rate; The monitoring module is used to monitor multiple different types of primary parameters; The dilution module is further configured to dilute the primary loop system with a second flow rate less than the first flow rate when any of the first parameters satisfies the first multiple switching condition; The monitoring module is also used to monitor multiple different types of second parameters; The dilution module is further configured to dilute the primary loop system with a third flow rate less than the second flow rate when any of the second parameters satisfies the second multiple switching condition; The monitoring module is also used to monitor multiple different types of third parameters; A stop module is used to stop diluting the primary loop system when any of the third parameters meets the multiple dilution stop conditions. A criticality maintenance module is used to maintain the pressurized water reactor in a critical state by adjusting the temperature regulating rod.

[0022] Thirdly, embodiments of this application also provide a computer device, which includes a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the above-described method.

[0023] Fourthly, embodiments of this application also provide a computer-readable storage medium storing a computer program, the computer program including program instructions that, when executed by a processor, can implement the above-described method.

[0024] This application provides a method, system, equipment, and medium for criticality control of a pressurized water reactor (PWR) in a nuclear power plant. The method includes: completely removing the shutdown rods and power control rods from the reactor core, and partially removing the temperature regulating rods from the reactor core; determining a first multiple switching condition, a second multiple switching condition, and a multiple dilution stop condition based on the boron concentration in the primary loop system and a preset count rate threshold; diluting the primary loop system at a first flow rate and monitoring multiple different types of first parameters; when any of the first parameters meets the first multiple switching condition, diluting the primary loop system at a second flow rate less than the first flow rate and monitoring multiple different types of second parameters; when any of the second parameters meets the second multiple switching condition, diluting the primary loop system at a third flow rate less than the second flow rate and monitoring multiple different types of third parameters; when any of the third parameters meets the multiple dilution stop condition, stopping the dilution of the primary loop system and maintaining the PWR in a critical state by adjusting the temperature regulating rods. The embodiments of this application do not require repeated adjustment of the control rod during the dilution process, and the dilution flow rate can be dynamically adjusted through multiple switching conditions during the dilution process. This enables effective switching between fast, medium, and slow dilution, ensuring that the pressurized water reactor approaches the critical point efficiently and improving the efficiency of reaching the critical point. Furthermore, multiple dilution stop conditions are set, so even if the equipment fails under a certain condition, it will not affect the flow rate switching and stop control, thereby improving the safety of critical point operation. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A schematic flowchart illustrating the criticality control method for a pressurized water reactor in a nuclear power plant, as provided in this application embodiment; Figure 2 A schematic diagram of a sub-process of the criticality control method for a pressurized water reactor in a nuclear power plant provided in an embodiment of this application; Figure 3a A schematic diagram of another sub-process of the criticality control method for a pressurized water reactor in a nuclear power plant provided in an embodiment of this application; Figure 3b A schematic diagram of the countdown rate trend provided in the embodiments of this application; Figure 4 A schematic diagram of another sub-process of the criticality control method for a pressurized water reactor in a nuclear power plant provided in an embodiment of this application; Figure 5A schematic block diagram of a criticality control system for a pressurized water reactor in a nuclear power plant, provided as an embodiment of this application; Figure 6 A schematic block diagram of a computer device provided in an embodiment of this application. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] It should be noted that any AI models, software tools, or components not belonging to this company appearing in the embodiments of this application are merely illustrative examples and do not represent actual use. All user personal information involved in the embodiments of this application has been obtained by authorized entities (who have known and consented) or fully authorized by all parties through various legal and compliant means. The collection, storage, use, processing, transmission, provision, and disclosure of the information, data, and signals involved all comply with relevant laws and regulations and do not violate public order and good morals.

[0029] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0030] It should also be understood that the terminology used in this application specification is for the purpose of describing particular embodiments only and is not intended to limit the application. As used in this application specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0031] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0032] This application provides a method, system, equipment, and medium for achieving criticality control in a pressurized water reactor of a nuclear power plant.

[0033] The entity executing the criticality control method for the pressurized water reactor of the nuclear power plant can be the criticality control system for the pressurized water reactor of the nuclear power plant provided in the embodiments of this application, or a computer device that integrates the criticality control system for the pressurized water reactor of the nuclear power plant. The criticality control system for the pressurized water reactor of the nuclear power plant can be implemented in hardware or software, and the computer device can be a terminal or a server.

[0034] Figure 1 This is a schematic flowchart of the criticality control method for a pressurized water reactor in a nuclear power plant provided in an embodiment of this application. Figure 1 As shown, the method includes the following steps S110-S160.

[0035] S110. Completely remove the shutdown rods and power control rods of the pressurized water reactor from the core, and partially remove the temperature regulating rods from the core.

[0036] In this embodiment, the stop rods and power control rods of the pressurized water reactor are completely removed from the core to ensure that the stop rods and power control rods do not participate in the initial adjustment of the core reactivity; the temperature control rods are partially removed from the core to reserve a certain adjustment margin to prepare for subsequent reactivity compensation after reaching criticality.

[0037] Specifically, the shutdown rods are raised to the top of the reactor, the power control rods are raised to the top of the reactor, and the temperature control rods are placed at a higher position (target position), so that the control rods are close to the fully raised position at reactor criticality, and the value of the temperature control rods within the reactor (e.g., 5 × 10⁻⁶) is considered. -4 Sufficient to increase flux; The target position of the temperature regulating rod can be preset according to the initial reactivity state of the pressurized water reactor, for example, retaining 30%-50% of its total insertion depth.

[0038] In this embodiment, the shutdown rod is used for rapid shutdown / safety interlocking of the reactor (specifically, a pressurized water reactor in this application) and does not participate in normal power regulation; the power control rod is used for wide-range reactivity and power level regulation; the temperature control rod is used for fine regulation, criticality maintenance, and temperature control. In this embodiment, the temperature control rod is the core execution component for maintaining criticality after reaching criticality.

[0039] It should be noted that the Neutron Instrumentation System (NIS) of this application includes a Source Range (SR) detector, an Intermediate Range (IR) detector, and a Power Range (PR) detector. The reactivity meter is an experimental instrument and is temporarily connected to the NIS during the experiment.

[0040] The SR detector is used to acquire the neutron count rate, inverse count rate ICRR, and neutron count rate doubling time; the IR detector is used to determine the current output current and the output current doubling time; and the reactivity meter is used to calculate the reactivity of the reactor core in real time based on the neutron signal from the NIS system.

[0041] It should be noted that, in this embodiment, the NIS protection setpoint needs to be set to an appropriate level before dilution is performed. For example, before reactor criticality, the NIS protection setpoint is set in segments and dynamically according to the subcritical dilution process to adapt it to the current neutron level and reactivity state. The setpoint is appropriately relaxed in the early stages of dilution to ensure smooth operation, and gradually tightened as criticality approaches to improve safety monitoring sensitivity, thereby avoiding malfunctions and ensuring reliable protection triggering under abnormal conditions, providing a safety threshold support for reaching criticality control.

[0042] In this embodiment of the application, a first flow rate, a second flow rate, and a third flow rate are set in advance before dilution. The first flow rate is defined as the high-speed dilution flow rate Q1, the second flow rate is the medium-speed dilution flow rate Q2, and the third flow rate is the slow-speed dilution flow rate Q3. Q1 is greater than Q2, and Q2 is greater than Q3.

[0043] Specifically, to improve experimental efficiency, the value of Q1 can be appropriately increased to quickly approach the criticality. However, Q1 should not exceed the assumed dilution flow rate for boron dilution accident analysis, and it is recommended not to exceed half of the assumed flow rate for boron dilution accidents, for example, set to half of the assumed flow rate for boron dilution accidents, where the assumed flow rate for boron dilution accidents is a known flow rate. Q2 should be less than Q1, approaching the criticality at a slower reactivity introduction rate under conditions closer to the criticality, and ensuring that the medium-rate dilution time is long enough to eliminate the boron concentration unevenness caused by rapid dilution. Q2 can be taken as 0.25×Q1~0.5×Q1. Q3 is a conservative flow rate (set to a reactivity introduction rate of less than 5×10). -3 The slow dilution time is long enough (1 hour recommended) to eliminate the uneven boron concentration caused by medium-speed dilution.

[0044] S120. Determine the first multiple switching condition, the second multiple switching condition, and the multiple dilution stop condition based on the boron concentration of the primary loop system and the preset count rate threshold.

[0045] In one embodiment, specifically, the boron concentration includes the current boron concentration and the theoretical critical boron concentration; see [link to relevant documentation]. Figure 2 Step S120 includes: S1201. Determine the maximum dilution water volume based on the current boron concentration, the theoretical critical boron concentration, and the total volume of the primary loop system.

[0046] In one embodiment, considering uncertainty, the maximum dilution water volume V can be calculated using the theoretical critical boron concentration CBC-100μg / g. max If the total dilution volume exceeds V max If the critical threshold has not yet been reached, dilution should be stopped immediately and the cause investigated to prevent the risk of dilution not being stopped due to the failure of monitoring measures.

[0047] Specifically, the required amount of dilution water to reach the theoretical critical boron concentration can be calculated based on the current boron concentration, the theoretical critical boron concentration, and the total volume of the primary loop system. Then, the required amount of dilution water is added to the preset amount of buoyancy (uncertainty) to determine the maximum amount of dilution water.

[0048] S1202. Determine the first boron concentration threshold and the second boron concentration threshold based on the theoretical critical boron concentration, the preset first concentration buoyancy, and the preset second concentration buoyancy.

[0049] In this embodiment, the first boron concentration threshold is CB1, the second boron concentration threshold is CB2, and the theoretical critical boron concentration is CBC. CB1 can use the theoretical critical boron concentration CBC + 100 μg / g, that is, the first concentration float is 100 μg / g. When the measured boron concentration reaches CB1, the medium-speed dilution is switched. CB2 can use the theoretical critical boron concentration CBC + 25 μg / g, that is, the second concentration float is 25 μg / g.

[0050] S1203. Determine the first extrapolated remaining water threshold and the second extrapolated remaining water threshold based on the theoretical critical boron concentration, the total volume, the first boron concentration threshold, and the second boron concentration threshold, respectively.

[0051] Specifically, in one embodiment, based on the total volume, a first residual water volume required to dilute the boron concentration in the primary loop system from the first boron concentration threshold to the theoretical critical boron concentration is determined, and a first extrapolated residual water volume threshold is determined based on the first residual water volume; based on the total volume, a second residual water volume required to dilute the boron concentration in the primary loop system from the second boron concentration threshold to the theoretical critical boron concentration is determined, and a second extrapolated residual water volume threshold is determined based on the second residual water volume.

[0052] Wherein, the first extrapolated remaining water threshold is V1, and the second extrapolated remaining water threshold is V2. In one embodiment, determining the first extrapolated remaining water threshold based on the first remaining water includes: determining an initial threshold for the first extrapolated remaining water based on the first remaining water and a preset first multiple, wherein the first multiple is greater than or equal to 1; determining whether the initial threshold for the first extrapolated remaining water is greater than or equal to a first water volume, wherein the first water volume is the water volume obtained by diluting the second flow rate for a first preset time; if it is greater than or equal to the first water volume, then the initial threshold for the first extrapolated remaining water is determined as the first extrapolated remaining water threshold; if it is less than the first water volume, then the first water volume is determined as the first extrapolated remaining water threshold.

[0053] For example, the first multiple is a value in [1,3], the first preset duration is 1h, and V1 can be 1 to 3 times the amount of water required to dilute boron concentration CB1 to the theoretical critical boron concentration CBC (considering that the extrapolation curve is not nonlinear), and V1 should not be less than Q2 (second flow rate) × 1h (i.e., the amount of water when diluting 1 at a medium flow rate Q2).

[0054] In one embodiment, determining the second extrapolated remaining water volume threshold based on the second remaining water volume includes: The second extrapolated remaining water volume initial threshold is determined based on the second remaining water volume and a preset second multiple, wherein the second multiple is greater than or equal to 1; it is determined whether the second extrapolated remaining water volume initial threshold is greater than or equal to the second water volume, wherein the second water volume is the water volume obtained by diluting the second preset time with the third flow rate; if it is greater than or equal to the second water volume, the second extrapolated remaining water volume initial threshold is determined as the second extrapolated remaining water volume threshold; if it is less than the second water volume, the second water volume is determined as the second extrapolated remaining water volume threshold.

[0055] For example, the second multiple is a value in [1,3], the second preset duration is 1h, V2 can be 1 to 3 times the amount of water required to dilute boron concentration CB2 to the theoretical critical boron concentration CBC, and V2 should not be less than Q3×1h (i.e. the amount of water when diluting 1 at a slow flow rate Q3 (third flow rate)).

[0056] In this embodiment, the first multiple and the second multiple can be the same or different, and the first preset duration can be the same or different.

[0057] S1204. Determine the first multiple switching condition, the second multiple switching condition, and the multiple dilution stop condition based on the countdown rate threshold, the maximum dilution water volume, the first boron concentration threshold, the second boron concentration threshold, the first extrapolated remaining water volume threshold, and the second extrapolated remaining water volume threshold.

[0058] In one embodiment, the countdown rate threshold includes a first countdown rate threshold and a second countdown rate threshold. Step S1204 specifically includes: determining the first multiple switching condition based on the first boron concentration threshold, the first extrapolated remaining water volume threshold, and the preset first countdown rate threshold; determining the second multiple switching condition based on the second boron concentration threshold, the second extrapolated remaining water volume threshold, and the preset second countdown rate threshold; and determining the multiple dilution stop condition based on the preset critical switching condition, the maximum dilution water volume, and the preset relationship between the current cumulative dilution water volume and the extrapolated total water volume.

[0059] S130. Dilute the primary loop system with a first flow rate and monitor multiple different types of first parameters.

[0060] In this embodiment, after the rod lifting operation, the primary loop system is rapidly diluted with a first flow rate, while multiple different types of first parameters are monitored in real time by a monitoring module.

[0061] Specifically, in one embodiment, the first parameter includes a first current countdown rate, a first current boron concentration, and a first current extrapolated remaining water volume. (See [link to relevant documentation]). Figure 3a Specifically, the following steps are used to monitor multiple different types of first parameters: S1301. Determine the first current count rate based on the reference count rate and the current source range neutron count rate of the pressurized water reactor.

[0062] In this embodiment, the first current count rate = reference count rate / current source range neutron count rate, and the current source range neutron count rate is the neutron count rate monitored in real time by the SR detector.

[0063] In one embodiment, after removing a portion of the temperature regulating rod from the reactor core, the method further includes: A reference count rate is obtained, which is the source range neutron count rate obtained before dilution of the primary loop system, or the source range neutron count rate obtained after dilution to a preset empirical boron concentration.

[0064] The following describes the ICRR mentioned in the embodiments of this application: During the reactor loading and commissioning process, leaked neutrons in the core are measured using source range (SR), intermediate range (IR), or power range (PR) detectors outside the reactor pressure vessel to monitor the core neutron flux level. The counts from the external detectors satisfy the subcritical multiplication formula N = Sl / (1-k eff ), where S is the neutron source strength, and l is the average time from neutron generation to neutron disappearance in the reactor. For a given reactor, S and l can be considered constants. From this formula, it can be seen that when the reactor core reaches criticality, i.e., the effective neutron multiplication factor (k)...eff When the count reaches 1, the detector count N (source range neutron count rate) tends to infinity, that is, the count rate 1 / N tends to 0.

[0065] During the reactor criticality process, a certain k is usually selected according to the test procedure. eff The count rate N0 of the external detector is used as the baseline count rate. The inverse count rate ICRR = N0 / N. Once the baseline count rate is selected, ICRR represents the degree of proximity to criticality. The reactor is critical when ICRR is 0. Using different baseline count rates to calculate ICRR will not affect the reactor's criticality point, but the degree of deviation from the criticality point will differ for the same ICRR.

[0066] S1302. Detect the boron concentration in the primary loop system and obtain the first current boron concentration.

[0067] S1303. Determine the first current extrapolated remaining water volume based on the first current countdown rate, the countdown rate trend, and the diluted water volume.

[0068] Wherein, the first current extrapolated remaining water volume is the difference between the critical water volume obtained by extrapolating the first current countdown rate and the current diluted water volume, and the current diluted water volume. The trend of the countdown rate in this embodiment is as follows: Figure 3b As shown, this indicates the correspondence between the count rate and the amount of diluted water. Because the neutron flux distribution and the boron differential value change in real time with dilution, the first currently extrapolated remaining water volume also changes in real time.

[0069] The extrapolated water volume mentioned in the embodiments of this application is explained below: According to the ICCR, it can be known that During the dilution process, the introduced reactivity is approximately proportional to the cumulative dilution volume V, which can be approximated as... Where b is a constant, then When the reactor reaches criticality, Keff=1 and ICCR=0. Therefore, in the coordinate system, the points of ICCR and the diluted water volume V are fitted together to form a straight line. Extending (extrapolating) this line to its intersection with the horizontal axis (V-axis) gives the extrapolated critical water volume (see schematic diagram). Figure 3b Because fluctuations in the count rate cause fluctuations in the ICCR, and because Keff is not strictly linear with the dilution volume, in engineering, the extrapolated critical volume will be continuously updated as dilution continues, and the extrapolated critical volume will be more accurate as it gets closer to the critical point.

[0070] It should be noted that this embodiment does not limit the execution order of steps S1301-S1303.

[0071] S140. When any of the first parameters satisfies the first multiple switching condition, the primary loop system is diluted with a second flow rate less than the first flow rate, and multiple different types of second parameters are monitored.

[0072] In this embodiment, the first multiple switching conditions include a first switching sub-condition, a second switching sub-condition, and a third switching sub-condition, wherein: The first switching sub-condition is that the first current countdown rate is less than or equal to the first countdown rate threshold; The second switching sub-condition is that the first current boron concentration is less than or equal to the first boron concentration threshold; The third switching sub-condition is that the first current extrapolated remaining water volume is less than or equal to the first extrapolated remaining water volume threshold.

[0073] In one specific embodiment, the first count rate threshold is ICRR1, which can be determined in the range of 0.2 to 0.4; the first boron concentration threshold is CB1; the first extrapolated residual water threshold is V1; and the first multiple switching condition includes: The countdown rate of SR reaches ICRR1; The boron concentration in the primary loop system reaches CB1; The extrapolated critical water requirement is less than or equal to V1.

[0074] In this embodiment, rapid dilution is achieved using a dilution flow rate Q1. When any of the conditions in the first multiple switching conditions are met, the process switches to medium-speed dilution.

[0075] In one embodiment, the second parameter includes a second current countdown rate, a second current boron concentration, and a second current extrapolated remaining water volume. (See also...) Figure 4 Specifically, the following steps are used to monitor multiple different types of first parameters: S1401. Determine the second current count rate based on the reference count rate and the current source range neutron count rate of the pressurized water reactor; In this embodiment, the second current count rate = reference count rate / current source range neutron count rate, and the current source range neutron count rate is the neutron count rate monitored in real time by the SR detector.

[0076] S1402. Detect the boron concentration in the primary loop system to obtain the second current boron concentration; S1403. Determine the second current extrapolated remaining water volume based on the second current countdown rate, the countdown rate trend, and the diluted water volume.

[0077] The second current extrapolated remaining water volume is the difference between the critical water volume obtained by extrapolating the second current count rate and the current diluted water volume and the current diluted water volume. As dilution occurs, the second current extrapolated remaining water volume will also change in real time due to the neutron flux distribution and the boron differential value.

[0078] It should be noted that this embodiment does not limit the execution order of steps S1401-S1403.

[0079] In this embodiment, the first boron concentration threshold CB1, the first count rate threshold ICRR1, and the first extrapolated residual water threshold V1 are independent control variables. Even if one condition fails, the dilution flow rate can still be effectively and promptly switched to a more conservative flow rate. By setting CB1, ICRR1, and V1 to corresponding k values ​​close to each other using the above method... eff That is, all three conditions point to similar switching points, and can ensure that there is still enough time for dilution after switching the dilution flow rate, so as to eliminate the uneven boron concentration caused by rapid dilution.

[0080] S150. When any of the second parameters satisfies the second multiple switching condition, the first loop system is diluted with a third flow rate less than the second flow rate, and multiple different types of third parameters are monitored.

[0081] In this embodiment, the second multiple switching condition includes a fourth switching sub-condition, a fifth switching sub-condition, and a sixth switching sub-condition, wherein: The fourth switching sub-condition is that the second current countdown rate is less than or equal to the second countdown rate threshold; The fifth switching sub-condition is that the second current boron concentration is less than or equal to the second boron concentration threshold. The sixth switching sub-condition is that the second current extrapolated remaining water volume is less than or equal to the second extrapolated remaining water volume threshold.

[0082] In one specific embodiment, the second count rate threshold is ICRR2, which can be determined from 0.1 to 0.2; the second boron concentration threshold is CB2; the second extrapolated residual water threshold is V2; and the second multiple switching condition includes: The count rate of SR reaches ICRR2; The boron concentration in the primary loop system reaches CB2; The extrapolated critical water requirement is less than or equal to V2.

[0083] In this embodiment, the dilution rate is medium-speed dilution at the dilution flow rate Q2. When any of the conditions in the second multiple switching conditions are met, the dilution rate is switched to slow-speed dilution.

[0084] In one embodiment, the third parameter includes a threshold value and the current cumulative dilution water volume. The threshold value includes at least one of the source range neutron count rate doubling time, the intermediate range output current doubling time, the current reactivity of the core, and the current output current of the intermediate range detector of the pressurized water reactor.

[0085] S160. When any of the third parameters meets the multiple dilution stop condition, the dilution of the primary loop system is stopped, and the pressurized water reactor is maintained in a critical state by adjusting the temperature regulating rod.

[0086] In this embodiment, the multiple dilution stop conditions include a critical switching condition, a dilution water volume switching condition, and an extrapolated water volume switching condition, wherein: The critical switching condition includes at least one of the following: The doubling time of the quantum count rate in the source range or the doubling time of the output current in the intermediate range is less than or equal to 200s; The current reactivity of the reactor core is 30 pcm; The current output current of the intermediate range detector of the pressurized water reactor reaches the current corresponding to 1E-3%FP; The condition for switching the dilution water volume is that the current cumulative dilution water volume is greater than the maximum dilution water volume; The extrapolation water volume switching condition is that the current cumulative dilution water volume is greater than or equal to the extrapolated total water volume, and the extrapolated total water volume is less than the maximum dilution water volume.

[0087] In this embodiment of the application, the critical value is extrapolated at a certain frequency during rapid and medium-rapid dilution using a count rate. During slow dilution, the extrapolation frequency of the critical value can be appropriately increased (i.e., the frequency of calculating the extrapolated water volume).

[0088] In one embodiment, maintaining the pressurized water reactor in a critical state by adjusting the temperature regulating rod includes: When the core reactivity is positive, the temperature regulating rod is inserted to introduce negative reactivity; when the core reactivity is negative, the temperature regulating rod is raised to introduce positive reactivity.

[0089] For example, when the reactivity meter detects that the core reactivity ρ > 0 (reactivity biased towards positive), a temperature control rod is inserted to increase neutron absorption, introducing negative reactivity and bringing the reactivity closer to 0; when the reactivity meter detects that the core reactivity ρ < 0 (reactivity biased towards negative), the temperature control rod is raised to decrease neutron absorption, introducing positive reactivity and bringing the reactivity closer to 0; through the above dynamic adjustment, the core reactivity is maintained at the critical state (ρ ≈ 0), achieving stable criticality of the pressurized water reactor.

[0090] Under normal circumstances, after dilution is stopped, the reactor is in a supercritical state, and it is necessary to maintain the reactor in a critical state by inserting a temperature regulating rod.

[0091] This embodiment sets multiple dilution stop conditions, including critical phenomena, total dilution volume, and extrapolated volume, to ensure timely cessation of dilution. This also prevents excessive introduction of reactivity and ensures critical safety, even if a monitoring method fails.

[0092] In summary, the embodiments of this application do not require repeated adjustment of the control rod during the dilution process, and the dilution flow rate can be dynamically adjusted through multiple switching conditions during the dilution process. This enables effective switching between fast, medium, and slow dilution, ensuring that the pressurized water reactor approaches the critical point efficiently, improving the efficiency of reaching the critical point. Furthermore, by setting multiple dilution stop conditions, even if the equipment fails under a certain condition, the flow rate switching and stop control will not be affected, thereby improving the safety of critical point operation.

[0093] Figure 5 This is a schematic block diagram of a criticality control system for a pressurized water reactor in a nuclear power plant, provided in an embodiment of this application. Figure 5 As shown, corresponding to the above-described pressurized water reactor (PWR) criticality control method for nuclear power plants, this application also provides a pressurized water reactor (PWR) criticality control system 500. This PWR criticality control system 500 includes modules for executing the above-described pressurized water reactor (PWR) criticality control method, and can be configured in a terminal or server. Specifically, please refer to... Figure 5 The criticality control system 500 for the pressurized water reactor of this nuclear power plant includes a rod lifting module 501, a condition determination module 502, a dilution module 503, a monitoring module 504, a stop module 505, and a criticality maintenance module 506, wherein: The rod lifting module 501 is used to completely remove the shutdown rod and power control rod of the pressurized water reactor from the reactor core, and to partially remove the temperature regulating rod from the reactor core. The condition determination module 502 is used to determine the first multiple switching condition, the second multiple switching condition, and the multiple dilution stop condition based on the boron concentration of the primary loop system and the preset count rate threshold. The dilution module 503 is used to dilute the primary loop system at a first flow rate; Monitoring module 504 is used to monitor multiple different types of first parameters; The dilution module 503 is further configured to dilute the primary loop system with a second flow rate less than the first flow rate when any of the first parameters meets the first multiple switching conditions; The monitoring module 504 is also used to monitor multiple different types of second parameters; The dilution module 503 is further configured to dilute the primary loop system with a third flow rate less than the second flow rate when any of the second parameters meets the second multiple switching condition; The monitoring module 504 is also used to monitor multiple different types of third parameters; The stop module 505 is used to stop the dilution of the primary loop system when any of the third parameters meets the multiple dilution stop conditions. Critical maintenance module 506 is used to maintain the pressurized water reactor in a critical state by adjusting the temperature regulating rod.

[0094] In some embodiments, the boron concentration includes the current boron concentration and the theoretical critical boron concentration, and the condition determination module 502 is specifically used for: The maximum dilution water volume is determined based on the current boron concentration, the theoretical critical boron concentration, and the total volume of the primary loop system. The first boron concentration threshold and the second boron concentration threshold are determined based on the theoretical critical boron concentration, the preset first concentration buoyancy, and the preset second concentration buoyancy, respectively. The first extrapolated residual water threshold and the second extrapolated residual water threshold are determined based on the theoretical critical boron concentration, the total volume, the first boron concentration threshold, and the second boron concentration threshold, respectively. The first multiple switching condition, the second multiple switching condition, and the multiple dilution stop condition are determined based on the countdown rate threshold, the maximum dilution water volume, the first boron concentration threshold, the second boron concentration threshold, the first extrapolated remaining water volume threshold, and the second extrapolated remaining water volume threshold.

[0095] In some embodiments, the countdown rate threshold includes a first countdown rate threshold and a second countdown rate threshold. When the condition determination module 502 performs the step of determining the first multiple switching condition, the second multiple switching condition, and the multiple dilution stop condition based on the countdown rate threshold, the maximum dilution water volume, the first boron concentration threshold, the second boron concentration threshold, the first extrapolated remaining water volume threshold, and the second extrapolated remaining water volume threshold, it is specifically used for: The first multiple switching condition is determined based on the first boron concentration threshold, the first extrapolated remaining water threshold, and the preset first count rate threshold. The second multiple switching condition is determined based on the second boron concentration threshold, the second extrapolated remaining water threshold, and the preset second count rate threshold. The multiple dilution stop condition is determined based on the preset critical switching condition, the maximum dilution water volume, and the preset relationship between the current cumulative dilution water volume and the extrapolated total water volume.

[0096] In some embodiments, when the condition determination module 502 performs the step of determining the first extrapolated residual water threshold and the second extrapolated residual water threshold based on the theoretical critical boron concentration, the total volume, the first boron concentration threshold, and the second boron concentration threshold, it is specifically used for: Based on the total volume, determine the first remaining water volume required to dilute the boron concentration in the primary loop system from the first boron concentration threshold to the theoretical critical boron concentration, and determine the first extrapolated remaining water volume threshold based on the first remaining water volume. Based on the total volume, determine the second amount of residual water required to dilute the boron concentration in the primary loop system from the second boron concentration threshold to the theoretical critical boron concentration, and determine the second extrapolated residual water threshold based on the second amount of residual water.

[0097] In some embodiments, when the condition determination module 502 performs the step of determining the first extrapolated remaining water volume threshold based on the first remaining water volume, it is specifically used for: The first extrapolated remaining water volume initial threshold is determined based on the first remaining water volume and the preset first multiple, wherein the first multiple is greater than or equal to 1; Determine whether the initial threshold of the first extrapolated remaining water volume is greater than or equal to the first water volume, where the first water volume is the water volume obtained by diluting the second flow rate for a first preset time. If it is greater than or equal to the first water volume, then the first extrapolated remaining water volume initial threshold is determined as the first extrapolated remaining water volume threshold. If it is less than the first water volume, then the first water volume is determined as the first extrapolated remaining water volume threshold.

[0098] In some embodiments, when the condition determination module 502 performs the step of determining the second extrapolated remaining water volume threshold based on the second remaining water volume, it is specifically used for: The second extrapolated remaining water volume initial threshold is determined based on the second remaining water volume and a preset second multiple, wherein the second multiple is greater than or equal to 1; Determine whether the initial threshold of the second extrapolated remaining water volume is greater than or equal to the second water volume, where the second water volume is the water volume obtained by diluting the second preset time with the third flow rate; If it is greater than or equal to the second water volume, then the initial threshold of the second extrapolated remaining water volume is determined as the second extrapolated remaining water volume threshold. If it is less than the second water volume, then the second water volume is determined as the second extrapolated remaining water volume threshold.

[0099] In some embodiments, the criticality control system 500 for the pressurized water reactor of the nuclear power plant further includes a baseline count rate acquisition module: The reference count rate acquisition module is used to acquire a reference count rate, which is the source range neutron count rate obtained before dilution of the primary loop system, or the source range neutron count rate obtained after dilution to a preset empirical boron concentration.

[0100] In some embodiments, the first parameter includes a first current countdown rate, a first current boron concentration, and a first current extrapolated residual water volume. When the monitoring module 504 performs the step of monitoring multiple different types of first parameters, it is specifically used for: The first current count rate is determined based on the baseline count rate and the current source range neutron count rate of the pressurized water reactor; The boron concentration of the primary loop system is detected to obtain the first current boron concentration; The first current extrapolated remaining water volume is determined based on the first current boron concentration, the countdown rate of the primary loop system, and the diluted water volume.

[0101] In some embodiments, the first multiple switching conditions include a first switching sub-condition, a second switching sub-condition, and a third switching sub-condition, wherein: The first switching sub-condition is that the first current countdown rate is less than or equal to the first countdown rate threshold; The second switching sub-condition is that the first current boron concentration is less than or equal to the first boron concentration threshold; The third switching sub-condition is that the first current extrapolated remaining water volume is less than or equal to the first extrapolated remaining water volume threshold.

[0102] In some embodiments, the second parameter includes a second current countdown rate, a second current boron concentration, and a second current extrapolated residual water volume. When the monitoring module 504 performs the step of monitoring multiple different types of second parameters, it is specifically used for: The second current count rate is determined based on the baseline count rate and the current source range neutron count rate of the pressurized water reactor; The boron concentration of the primary loop system is detected to obtain the second current boron concentration; The second current extrapolated remaining water volume is determined based on the second current boron concentration, the count rate of the primary loop system, and the diluted water volume.

[0103] In some embodiments, the second multiple switching conditions include a fourth switching sub-condition, a fifth switching sub-condition, and a sixth switching sub-condition, wherein: The fourth switching sub-condition is that the second current countdown rate is less than or equal to the second countdown rate threshold; The fifth switching sub-condition is that the second current boron concentration is less than or equal to the second boron concentration threshold. The sixth switching sub-condition is that the second current extrapolated remaining water volume is less than or equal to the second extrapolated remaining water volume threshold.

[0104] In some embodiments, the third parameter includes a threshold value and the current cumulative dilution water volume, the threshold value including at least one of the source range neutron count rate doubling time, the intermediate range output current doubling time, the current reactivity of the core, and the current output current of the intermediate range detector of the pressurized water reactor.

[0105] In some embodiments, the multiple dilution stop conditions include a critical switching condition, a dilution water volume switching condition, and an extrapolated water volume switching condition, wherein: The critical switching condition includes at least one of the following: The doubling time of the quantum count rate in the source range or the doubling time of the output current in the intermediate range is less than or equal to 200s; The current reactivity of the reactor core is 30 pcm; The current output current of the intermediate range detector of the pressurized water reactor reaches the current corresponding to 1E-3%FP; The condition for switching the dilution water volume is that the current cumulative dilution water volume is greater than the maximum dilution water volume; The extrapolation water volume switching condition is that the current cumulative dilution water volume is greater than or equal to the extrapolated total water volume, and the extrapolated total water volume is less than the maximum dilution water volume.

[0106] In some embodiments, the criticality maintenance module 506 is specifically used for: When the core reactivity is positive, the temperature regulating rod is inserted to introduce negative reactivity; When the core reactivity is negative, the temperature regulating rod is raised to introduce positive reactivity.

[0107] In summary, the embodiments of this application do not require repeated adjustment of the control rod during the dilution process, and the dilution flow rate can be dynamically adjusted through multiple switching conditions during the dilution process. This enables effective switching between fast, medium, and slow dilution, ensuring that the pressurized water reactor approaches the critical point efficiently, improving the efficiency of reaching the critical point. Furthermore, by setting multiple dilution stop conditions, even if the equipment fails under a certain condition, the flow rate switching and stop control will not be affected, thereby improving the safety of critical point operation.

[0108] It should be noted that those skilled in the art can clearly understand that the specific implementation process of the criticality control system and each unit of the above-mentioned nuclear power plant pressurized water reactor can be referred to the corresponding description in the foregoing method embodiments. For the sake of convenience and brevity, it will not be repeated here.

[0109] The criticality control system for the aforementioned pressurized water reactor in a nuclear power plant can be implemented as a computer program, which can be used in, for example... Figure 6 It runs on the computer device shown.

[0110] Please see Figure 6 , Figure 6 This is a schematic block diagram of a computer device provided in an embodiment of this application. The computer device 600 can be a terminal or a server.

[0111] See Figure 6 The computer device 600 includes a processor 602, a memory, and a network interface 605 connected via a system bus 601. The memory may include a non-volatile storage medium 603 and internal memory 604.

[0112] The non-volatile storage medium 603 may store an operating system 6031 and a computer program 6032. The computer program 6032 includes program instructions that, when executed, cause the processor 602 to perform a criticality control method for a pressurized water reactor in a nuclear power plant.

[0113] The processor 602 provides computing and control capabilities to support the operation of the entire computer device 600.

[0114] The internal memory 604 provides an environment for the operation of the computer program 6032 in the non-volatile storage medium 603. When the computer program 6032 is executed by the processor 602, the processor 602 can execute a criticality control method for a pressurized water reactor in a nuclear power plant.

[0115] This network interface 605 is used for network communication with other devices. Those skilled in the art will understand that... Figure 6 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device 600 to which the present application is applied. The specific computer device 600 may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0116] The processor 602 is used to run a computer program 6032 stored in the memory to perform the following steps: Completely remove the shutdown rods and power control rods of the pressurized water reactor from the core, and partially remove the temperature regulating rods from the core. The first multiple switching condition, the second multiple switching condition, and the multiple dilution stop condition are determined based on the boron concentration of the primary loop system and the preset count rate threshold. The primary loop system is diluted with a first flow rate, and multiple different types of first parameters are monitored; When any of the first parameters satisfies the first multiple switching condition, the first loop system is diluted with a second flow rate less than the first flow rate, and multiple different types of second parameters are monitored. When any of the second parameters satisfies the second multiple switching condition, the first loop system is diluted with a third flow rate less than the second flow rate, and multiple different types of third parameters are monitored. When any of the third parameters meets the multiple dilution stop condition, the dilution of the primary loop system is stopped, and the pressurized water reactor is maintained in a critical state by adjusting the temperature regulating rod.

[0117] It should be understood that, in the embodiments of this application, the processor 602 may be a Central Processing Unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0118] It will be understood by those skilled in the art that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program includes program instructions and can be stored in a storage medium, which is a computer-readable storage medium. The program instructions are executed by at least one processor in the computer system to implement the process steps of the embodiments of the above methods.

[0119] Therefore, this application also provides a storage medium. This storage medium can be a computer-readable storage medium. The storage medium stores a computer program, wherein the computer program includes program instructions. When executed by a processor, the program instructions cause the processor to perform the criticality control method for a pressurized water reactor in a nuclear power plant provided in the embodiments of this application.

[0120] The storage medium can be any computer-readable storage medium capable of storing program code, such as a USB flash drive, portable hard drive, read-only memory (ROM), magnetic disk, or optical disk.

[0121] Those skilled in the art will 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 application.

[0122] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For example, the division of each unit is merely a logical functional division, and there may be other division methods in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed.

[0123] The steps in the methods of this application embodiment can be adjusted, merged, or deleted according to actual needs. The units in the apparatus of this application embodiment can be merged, divided, or deleted according to actual needs. Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0124] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, a terminal, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application.

[0125] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for achieving criticality control in a pressurized water reactor of a nuclear power plant, characterized in that, include: Completely remove the shutdown rods and power control rods of the pressurized water reactor from the core, and partially remove the temperature regulating rods from the core. The first multiple switching condition, the second multiple switching condition, and the multiple dilution stop condition are determined based on the boron concentration of the primary loop system and the preset count rate threshold. The primary loop system is diluted with a first flow rate, and multiple different types of first parameters are monitored; When any of the first parameters satisfies the first multiple switching condition, the first loop system is diluted with a second flow rate less than the first flow rate, and multiple different types of second parameters are monitored. When any of the second parameters satisfies the second multiple switching condition, the first loop system is diluted with a third flow rate less than the second flow rate, and multiple different types of third parameters are monitored. When any of the third parameters meets the multiple dilution stop condition, the dilution of the primary loop system is stopped, and the pressurized water reactor is maintained in a critical state by adjusting the temperature regulating rod.

2. The method according to claim 1, characterized in that, The boron concentration includes the current boron concentration and the theoretical critical boron concentration. Determining the first multiple switching condition, the second multiple switching condition, and the multiple dilution stop condition based on the boron concentration of the primary loop system and a preset count rate threshold includes: The maximum dilution water volume is determined based on the current boron concentration, the theoretical critical boron concentration, and the total volume of the primary loop system. The first boron concentration threshold and the second boron concentration threshold are determined based on the theoretical critical boron concentration, the preset first concentration buoyancy, and the preset second concentration buoyancy, respectively. The first extrapolated residual water threshold and the second extrapolated residual water threshold are determined based on the theoretical critical boron concentration, the total volume, the first boron concentration threshold, and the second boron concentration threshold, respectively. The first multiple switching condition, the second multiple switching condition, and the multiple dilution stop condition are determined based on the countdown rate threshold, the maximum dilution water volume, the first boron concentration threshold, the second boron concentration threshold, the first extrapolated remaining water volume threshold, and the second extrapolated remaining water volume threshold.

3. The method according to claim 2, characterized in that, The countdown rate threshold includes a first countdown rate threshold and a second countdown rate threshold. Determining the first multiple switching condition, the second multiple switching condition, and the multiple dilution stop condition based on the countdown rate threshold, the maximum dilution water volume, the first boron concentration threshold, the second boron concentration threshold, the first extrapolated remaining water volume threshold, and the second extrapolated remaining water volume threshold includes: The first multiple switching condition is determined based on the first boron concentration threshold, the first extrapolated remaining water threshold, and the preset first count rate threshold. The second multiple switching condition is determined based on the second boron concentration threshold, the second extrapolated remaining water threshold, and the preset second count rate threshold. The multiple dilution stop condition is determined based on the preset critical switching condition, the maximum dilution water volume, and the preset relationship between the current cumulative dilution water volume and the extrapolated total water volume.

4. The method according to claim 2, characterized in that, The step of determining the first extrapolated residual water threshold and the second extrapolated residual water threshold based on the theoretical critical boron concentration, the total volume, the first boron concentration threshold, and the second boron concentration threshold, respectively, includes: Based on the total volume, determine the first remaining water volume required to dilute the boron concentration in the primary loop system from the first boron concentration threshold to the theoretical critical boron concentration, and determine the first extrapolated remaining water volume threshold based on the first remaining water volume. Based on the total volume, determine the second amount of residual water required to dilute the boron concentration in the primary loop system from the second boron concentration threshold to the theoretical critical boron concentration, and determine the second extrapolated residual water threshold based on the second amount of residual water.

5. The method according to claim 4, characterized in that, Determining the first extrapolated remaining water volume threshold based on the first remaining water volume includes: The first extrapolated remaining water volume initial threshold is determined based on the first remaining water volume and the preset first multiple, wherein the first multiple is greater than or equal to 1; Determine whether the initial threshold of the first extrapolated remaining water volume is greater than or equal to the first water volume, where the first water volume is the water volume obtained by diluting the second flow rate for a first preset time. If it is greater than or equal to the first water volume, then the first extrapolated remaining water volume initial threshold is determined as the first extrapolated remaining water volume threshold. If it is less than the first water volume, then the first water volume is determined as the first extrapolated remaining water volume threshold.

6. The method according to claim 4, characterized in that, The step of determining the second extrapolated remaining water volume threshold based on the second remaining water volume includes: The second extrapolated remaining water volume initial threshold is determined based on the second remaining water volume and a preset second multiple, wherein the second multiple is greater than or equal to 1; Determine whether the initial threshold of the second extrapolated remaining water volume is greater than or equal to the second water volume, where the second water volume is the water volume obtained by diluting the second preset time with the third flow rate; If it is greater than or equal to the second water volume, then the initial threshold of the second extrapolated remaining water volume is determined as the second extrapolated remaining water volume threshold. If it is less than the second water volume, then the second water volume is determined as the second extrapolated remaining water volume threshold.

7. The method according to claim 1, characterized in that, After completely removing the shutdown rods and power control rods of the pressurized water reactor from the core, and partially removing the temperature regulating rods from the core, the method further includes: A reference count rate is obtained, which is the source range neutron count rate obtained before dilution of the primary loop system, or the source range neutron count rate obtained after dilution to a preset empirical boron concentration.

8. The method according to claim 7, characterized in that, The first parameter includes a first current countdown rate, a first current boron concentration, and a first current extrapolated residual water volume. The monitoring of multiple different types of first parameters includes: The first current count rate is determined based on the baseline count rate and the current source range neutron count rate of the pressurized water reactor; The boron concentration of the primary loop system is detected to obtain the first current boron concentration; The first current extrapolated remaining water volume is determined based on the first current countdown rate, the countdown rate trend, and the diluted water volume.

9. The method according to claim 8, characterized in that, The first multiple switching conditions include a first switching sub-condition, a second switching sub-condition, and a third switching sub-condition, wherein: The first switching sub-condition is that the first current countdown rate is less than or equal to the first countdown rate threshold; The second switching sub-condition is that the first current boron concentration is less than or equal to the first boron concentration threshold; The third switching sub-condition is that the first current extrapolated remaining water volume is less than or equal to the first extrapolated remaining water volume threshold.

10. The method according to claim 7, characterized in that, The second parameter includes the second current countdown rate, the second current boron concentration, and the second current extrapolated residual water volume. The monitoring of multiple different types of second parameters includes: The second current count rate is determined based on the baseline count rate and the current source range neutron count rate of the pressurized water reactor; The boron concentration of the primary loop system is detected to obtain the second current boron concentration; The second current extrapolated remaining water volume is determined based on the second current countdown rate, the countdown rate trend, and the diluted water volume.

11. The method according to claim 10, characterized in that, The second multiple switching condition includes a fourth switching sub-condition, a fifth switching sub-condition, and a sixth switching sub-condition, wherein: The fourth switching sub-condition is that the second current countdown rate is less than or equal to the second countdown rate threshold; The fifth switching sub-condition is that the second current boron concentration is less than or equal to the second boron concentration threshold. The sixth switching sub-condition is that the second current extrapolated remaining water volume is less than or equal to the second extrapolated remaining water volume threshold.

12. The method according to claim 1, characterized in that, The third parameter includes a critical value and the current cumulative dilution water volume. The critical value includes at least one of the following: the source range neutron count rate doubling time, the intermediate range output current doubling time, the current reactivity of the reactor core, and the current output current of the intermediate range detector of the pressurized water reactor. The multiple dilution stop conditions include a critical switching condition, a dilution water volume switching condition, and an extrapolated water volume switching condition, wherein: The critical switching condition includes at least one of the following: The doubling time of the quantum count rate in the source range or the doubling time of the output current in the intermediate range is less than or equal to 200s; The current reactivity of the reactor core is 30 pcm; The current output current of the intermediate range detector of the pressurized water reactor reaches the current corresponding to 1E-3%FP; The condition for switching the dilution water volume is that the current cumulative dilution water volume is greater than the maximum dilution water volume; The extrapolation water volume switching condition is that the current cumulative dilution water volume is greater than or equal to the extrapolated total water volume, and the extrapolated total water volume is less than the maximum dilution water volume.

13. A criticality control system for a pressurized water reactor in a nuclear power plant, characterized in that, include: The rod lifting module is used to completely remove the shutdown rod and power control rod of the pressurized water reactor from the reactor core, and to partially remove the temperature regulating rod from the reactor core. The condition determination module is used to determine the first multiple switching condition, the second multiple switching condition, and the multiple dilution stop condition based on the boron concentration of the primary loop system and the preset count rate threshold. A dilution module for diluting the primary loop system at a first flow rate; The monitoring module is used to monitor multiple different types of primary parameters; The dilution module is further configured to dilute the primary loop system with a second flow rate less than the first flow rate when any of the first parameters satisfies the first multiple switching condition; The monitoring module is also used to monitor multiple different types of second parameters; The dilution module is further configured to dilute the primary loop system with a third flow rate less than the second flow rate when any of the second parameters satisfies the second multiple switching condition; The monitoring module is also used to monitor multiple different types of third parameters; A stop module is used to stop diluting the primary loop system when any of the third parameters meets the multiple dilution stop conditions. A criticality maintenance module is used to maintain the pressurized water reactor in a critical state by adjusting the temperature regulating rod.

14. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the criticality control method for a pressurized water reactor in a nuclear power plant as described in any one of claims 1-12.

15. A storage medium, characterized in that, The storage medium stores a computer program, which includes program instructions that, when executed by a processor, cause the processor to perform the criticality control method for a pressurized water reactor in a nuclear power plant as described in any one of claims 1-12.

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