Method, system and medium for calculating personnel intervention time in the event of a spent fuel pool accident scenario

Abstract

The application provides a personnel intervenable time calculation method, system and medium under a spent pool accident scenario, and relates to the field of nuclear power. The personnel intervenable time calculation method comprises the following steps: obtaining refueling data of a nuclear power plant, and calculating total decay heat power of the spent pool before an accident according to the refueling data; obtaining spent pool data of the spent fuel pool and the number of newly added spent fuel assemblies corresponding to each accident time within the total duration of the accident; calculating a boiling time through time step iteration according to the number of newly added spent fuel assemblies, the spent pool data and the total decay heat power of the spent pool before the accident; and calculating a water supply starting time, a water supply ending time and a total required water supply amount through time step iteration according to the boiling time, the number of newly added spent fuel assemblies, the spent pool data and the total decay heat power of the spent pool before the accident.

Description

Technical Field

[0001] This application mainly relates to the field of nuclear power, and in particular to a method, system and medium for calculating the time of human intervention in a spent pool accident scenario. Background Technology

[0002] In the Probabilistic Safety Assessment (PSA) framework for passive nuclear power plants, Human Reliability Analysis (HRA) is a crucial step in quantifying plant risks. These risks include Core Damage Frequency (CDF) and Large Early Release Frequency (LERF). The accuracy of HRA directly determines the reliability of the PSA model's assessment of the risk contribution of accident sequences, especially when personnel actions serve as a critical barrier in the defense-in-depth mechanism for accident mitigation.

[0003] The spent fuel pool of a nuclear power plant faces extreme risks of boiling, exposure, and even radioactive release under beyond-design-baseline accidents such as a complete plant blackout. Therefore, the spent fuel pool accident sequence is of indispensable strategic importance to the integrity of the Power Supply Safety (PSA) system. The spent fuel pool PSA model involves numerous time-sensitive human operations, such as starting standby pumps, switching valves, and implementing emergency water replenishment. The reliability analysis of these human operations is one of the decisive factors in ensuring the accuracy of spent fuel pool PSA risk quantification. The core input parameter of the HRA model includes the accurate calculation of the available time for human intervention. This means that any overly conservative estimation of the time window will lead to an inflated Human Error Probability (HEP), or any underestimation of the time window will mask the true risk. In other words, both overly conservative and underestimation will directly distort the assessment of the overall risk of a spent fuel pool accident.

[0004] Current research on wastewater safety has made some progress in the field of real-time monitoring of thermal hydraulics. However, these existing technologies focus on solving the problem of online diagnosis of physical state parameters such as temperature, pressure, and boiling point, thereby providing operators with early warnings. However, at the level of supporting probabilistic safety analysis, especially when it comes to the in-depth risk quantification of multi-type accident sequences such as loss of cooling source, loss of coolant accident (LOCA) caused by pipeline rupture, and plant-wide power outage, existing technologies do not provide corresponding solutions.

[0005] Therefore, there is an urgent need for a method to calculate the time for human intervention in a wastewater accident scenario that can obtain accurate data on the time window for human intervention. Summary of the Invention

[0006] The technical problem to be solved by this application is to provide a method, system and medium for calculating the time of intervention by personnel in the event of a wastewater accident, which can obtain accurate data on the time window of intervention by personnel.

[0007] To address the aforementioned technical problems, this application provides a method for calculating the time of intervention for personnel in a spent fuel pool accident scenario. This method is applicable to spent fuel pools located in nuclear power plants, where the nuclear power plant includes a reactor, and the spent fuel pool is suitable for storing spent fuel assemblies. The spent fuel assemblies include fuel assemblies removed from the reactor. The method for calculating the time of intervention includes: acquiring refueling data from the nuclear power plant and calculating the total decay heat power of the spent fuel pool before the accident based on the refueling data; acquiring spent fuel pool data and the number of newly added spent fuel assemblies at each accident moment within the total accident duration; calculating the boiling moment through time step iterations based on the number of newly added spent fuel assemblies, the spent fuel pool data, and the total decay heat power of the spent fuel pool before the accident; and calculating the water replenishment start moment, water replenishment end moment, and total required water replenishment volume through time step iterations based on the boiling moment, the number of newly added spent fuel assemblies, the spent fuel pool data, and the total decay heat power of the spent fuel pool before the accident.

[0008] Optionally, the refueling data includes the storage years of spent fuel assemblies in the spent fuel pool, the reactor's shutdown duration, the reactor core power, and the number of fuel assemblies removed from the reactor during a single refueling operation. The formula for calculating the total decay heat power of the spent fuel pool before the accident is as follows: ,in, , In the formula The storage life of spent fuel assemblies. The spent fuel pool already contained fuel from before the accident. The total decay heat power of the spent fuel assembly within the year corresponds to the pre-accident total decay heat power of the spent fuel pool. This is the duration of the reactor shutdown. This refers to the quantity of materials changed in a single transaction. This represents the total number of fuel assemblies in the reactor. For the reactor in Time of the first The correction factor for neutron capture of individual nuclides. For the first The energy released by a single fission of a nuclide The total number of nuclides, For core power, and For the first The exponential fitting parameters of the thermal neutron fission function of each nuclide. For the first The total number of exponential fitting parameters corresponding to each nuclide.

[0009] Optionally, the step of calculating the boiling moment through time step iteration based on the number of newly added spent fuel assemblies, spent pool data, and the total decay heat power of the spent pool before the accident further includes: calculating the spent fuel decay heat and the total energy required for boiling at each accident moment through time step iteration based on the number of newly added spent fuel assemblies, spent pool data, and the total decay heat power of the spent pool before the accident; sequentially determining whether the spent fuel decay heat and the total energy required for boiling at each accident moment are equal; if the determination result is yes, then the current accident moment is taken as the boiling moment.

[0010] Optionally, the step of calculating the boiling moment through time step iteration based on the number of newly added spent fuel assemblies, spent fuel pool data, and the total decay heat power of the spent fuel pool before the accident further includes: when the spent fuel decay heat and the total energy required for boiling are not equal at all accident moments, the accident moment corresponding to the smallest positive value of the difference between the spent fuel decay heat and the total energy required for boiling is taken as the first time point, and the accident moment corresponding to the largest negative value of the difference between the spent fuel decay heat and the total energy required for boiling is taken as the second time point, and the boiling moment is calculated based on the first time point and the second time point.

[0011] Optionally, the spent fuel pool is equipped with a spent fuel pool grid and fuel transport channels. The spent fuel pool data includes the length, width, and bottom height of the spent fuel pool; the length, width, and height of the fuel transport channels; the grid volume of the spent fuel pool; the saturated density of the liquid in the spent fuel pool; and the total volume of the spent fuel assemblies in the spent fuel pool. The calculation expression for the decay heat of the spent fuel is as follows: ,in, , , , , , , In the formula and The time of the accident and the moment of the accident The corresponding decay heat of spent fuel, The spent fuel pool already contained fuel from before the accident. The total decay heat power of the spent fuel assembly within the year corresponds to the pre-accident total decay heat power of the spent fuel pool. This is the duration of the reactor shutdown. For the moment of the accident The number of newly added spent fuel assemblies, This represents the total number of fuel assemblies in the reactor during a single refueling operation. For the reactor during an accident No. The correction factor for neutron capture of individual nuclides. For the first The energy released by a single fission of a nuclide The total number of nuclides, For core power, and For the first The exponential fitting parameters of the thermal neutron fission function of each nuclide. For the first The total number of exponential fitting parameters corresponding to each nuclide. For saturated density, The length of the spent fuel pool Width of the spent fuel pool This refers to the bottom height of the spent fuel pool. For the volume of the lattice, The total volume of the component. For channel length, For channel width, For the channel height, For the moment of the accident The corresponding flow rate at the breach.

[0012] Optionally, the spent fuel pool is equipped with a spent fuel pool grid and a fuel transport channel. The spent fuel pool data includes the length, width, and bottom height of the spent fuel pool; the length, width, and height of the fuel transport channel; the grid volume of the spent fuel pool; the saturated density of the liquid in the spent fuel pool; and the total volume of the spent fuel assemblies in the spent fuel pool. The formula for calculating the total energy required for boiling is as follows: ,in, , , , , In the formula For the moment of the accident The total energy required for boiling. For saturated density, The length of the spent fuel pool Width of the spent fuel pool This refers to the bottom height of the spent fuel pool. For the volume of the lattice, The total volume of the component. For channel length, For channel width, For the channel height, For the moment of the accident The corresponding break flow rate, This represents the enthalpy of the spent fuel pool under saturation conditions. This represents the enthalpy of the spent fuel pool at the initial water temperature.

[0013] Optionally, the water replenishment start time is the time point corresponding to the liquid level height in the spent fuel pool being the height of the water replenishment point, the water replenishment end time is the time point corresponding to the liquid level height in the spent fuel pool being the height of the invalid point, and the total required water replenishment volume is the water replenishment volume corresponding to the final accident time corresponding to the total duration of the accident.

[0014] Optionally, the spent fuel pool is equipped with a spent fuel pool grid and a fuel transport channel. The spent fuel pool data includes the length, width, and bottom height of the spent fuel pool; the length, width, and height of the fuel transport channel; the grid volume of the spent fuel pool; the saturated density and latent heat of vaporization of the liquid in the spent fuel pool; and the total volume of the spent fuel assemblies in the spent fuel pool. The formula for calculating the liquid level is: ,in, , , , , , , , , , For the moment of the accident The total energy required for boiling. For saturated density, The length of the spent fuel pool Width of the spent fuel pool This refers to the bottom height of the spent fuel pool. For the volume of the lattice, The total volume of the component. For channel length, For channel width, For channel height For the moment of the accident The corresponding break flow rate, This is the latent heat of vaporization.

[0015] Optionally, the formula for calculating the water replenishment volume is: In the formula and The time of the accident and the moment of the accident The corresponding water replenishment volume.

[0016] Optionally, the wastewater data also includes the break height and initial liquid level, and the break flow rate. The calculation expression is: ,in, In the formula The height of the breach. This is the total resistance coefficient of the fuel transport route. For the moment of the accident The liquid level height, This represents the enthalpy of the spent fuel pool under saturation conditions. The enthalpy of the spent fuel pool at the initial water temperature is given. The initial moment of the accident. Initial time The corresponding initial liquid level height, where, when there is no breach in the spent fuel pool, the breach height is the liquid level height at the current moment.

[0017] Optionally, the flow rate at the breach It is calculated using a preset static liquid level drop curve.

[0018] To address the aforementioned technical problems, this application provides a system for calculating the time at which personnel can intervene in a low-energy-density battery accident scenario, comprising: a memory for storing instructions executable by a processor; and a processor for executing the instructions to implement the aforementioned method for calculating the time at which personnel can intervene in a low-energy-density battery accident scenario.

[0019] To address the aforementioned technical problems, this application provides a computer-readable medium storing computer program code, which, when executed by a processor, implements the aforementioned method for calculating the time at which personnel can intervene in a low-energy-density battery accident scenario.

[0020] Compared with existing technologies, this application has the following advantages: It calculates the total decay heat power of the spent fuel pool before the accident, corresponding to the spent fuel assemblies already stored in the pool before the accident, based on refueling data, which more closely reflects the actual operating conditions of a spent fuel pool. Furthermore, by combining the spent fuel pool data and the number of newly added spent fuel assemblies, it sequentially calculates the key boiling point, water replenishment start point, water replenishment end point, and total required water replenishment volume within the personnel intervention time window data. Since the aforementioned personnel intervention time window data is obtained through iterative time-step calculations, it more closely reflects the actual scenario and improves the accuracy and precision of the calculation results. Attached Figure Description

[0021] The accompanying drawings are included to provide a further understanding of this application; they are incorporated into and constitute a part of this application. The drawings illustrate embodiments of this application and, together with this specification, serve to explain the principles of this application. In the drawings:

[0022] Figure 1 This is a flowchart illustrating a method for calculating the time available for human intervention in a wastewater accident scenario, according to an embodiment of this application.

[0023] Figure 2 yes Figure 1 A flowchart illustrating the sub-steps of step S3 in the middle section;

[0024] Figure 3 This is a partial structural schematic diagram of a nuclear power plant according to an embodiment of this application; and

[0025] Figure 4 This is a schematic diagram of a human intervention time calculation system in a wastewater accident scenario according to an embodiment of this application. Detailed Implementation

[0026] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this application. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0027] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not specifically singular and may include plural forms. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0028] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0029] In the description of this application, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0030] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0031] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. In addition, although the terminology used in this application is selected from commonly known and used terms, some terms mentioned in this application's specification may have been chosen by the applicant according to his or her judgment, and their detailed meanings are explained in the relevant sections of this description. Moreover, this application should be understood not only through the actual terms used, but also through the meaning implied by each term.

[0032] It should be understood that when a component is referred to as "on another component," "connected to another component," "coupled to another component," or "in contact with another component," it can be directly on, connected to, coupled to, or in contact with that other component, or there may be an intervening component. In contrast, when a component is referred to as "directly on another component," "directly connected to," "directly coupled to," or "directly in contact with" another component, there is no intervening component. Similarly, when a first component is referred to as "electrically contacting" or "electrically coupled to" a second component, there is an electrical path between the first and second components that allows current to flow. This electrical path may include capacitors, coupled inductors, and / or other components that allow current to flow, even if there is no direct contact between the conductive components.

[0033] Flowcharts are used in this application to illustrate the operations performed by the system according to embodiments of this application. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, various steps can be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more steps may be removed from these processes.

[0034] Reference Figure 1 One embodiment of this application proposes a method 100 for calculating the time of intervention by personnel in a spent fuel pool accident scenario (hereinafter referred to as the intervention time calculation method 100), and this intervention time calculation method 100 is applicable to spent fuel pools located in nuclear power plants. The nuclear power plant includes a reactor, and the spent fuel pool is suitable for storing spent fuel assemblies. It should be noted that the reactor includes multiple sets of fuel assemblies, and after operating in the reactor for a specified period, the fuel assemblies can no longer continue to operate in the reactor, thus becoming spent fuel assemblies and needing to be stored in the spent fuel pool for a certain number of years, such as 15 years. Finally, the spent fuel assemblies stored for the specified period will be removed from the spent fuel pool for subsequent processing or utilization. Therefore, in this embodiment, the spent fuel assemblies in the spent fuel pool include fuel assemblies removed from the reactor.

[0035] Continue to refer to Figure 1 The method 100 for calculating the time of intervention by personnel includes the following steps: Step S1 is to acquire the refueling data of the nuclear power plant and calculate the total decay heat power of the spent fuel pool before the accident based on the refueling data. Step S2 is to acquire the spent fuel pool data and the number of newly added spent fuel assemblies corresponding to each accident moment within the total accident duration. Step S3 is to calculate the boiling moment through time step iteration based on the number of newly added spent fuel assemblies, spent fuel pool data, and the total decay heat power of the spent fuel pool before the accident. Step S4 is to calculate the makeup water start moment, makeup water end moment, and total required makeup water volume through time step iteration based on the boiling moment, the number of newly added spent fuel assemblies, spent fuel pool data, and the total decay heat power of the spent fuel pool before the accident.

[0036] The personnel intervention time calculation method 100 in this embodiment calculates the total decay heat power of the spent fuel pool corresponding to the spent fuel pool that already contained spent fuel assemblies before the accident, based on the refueling data from steps S1 to S4, thus more closely reflecting the actual operation of the spent fuel pool. On this basis, the personnel intervention time calculation method 100 further combines the spent fuel pool data and the number of newly added spent fuel assemblies to sequentially calculate the key boiling moment, water replenishment start moment, water replenishment end moment, and total required water replenishment volume in the personnel intervention time window data. Since the above personnel intervention time window data is obtained through time-step iterative calculation, it more closely reflects the actual scenario and improves the accuracy and precision of the calculation results.

[0037] The details of steps S1 to S4 are further explained below. In some embodiments, the refueling data includes the storage years of spent fuel assemblies in the spent fuel pool, the reactor's shutdown duration, the reactor core power, and the number of fuel assemblies removed from the reactor during a single refueling. Accordingly, the expression for calculating the total decay heat power of the spent fuel pool before the accident is:

[0038] ,in,

[0039] ,

[0040] ,

[0041] In the formula The storage life of spent fuel assemblies. The spent fuel pool already contained fuel from before the accident. The total decay heat power of the spent fuel assembly within the year corresponds to the pre-accident total decay heat power of the spent fuel pool. This is the duration of the reactor shutdown. This refers to the quantity of materials changed in a single transaction. This represents the total number of fuel assemblies in the reactor. For the reactor in Time of the first The correction factor for neutron capture of individual nuclides. For the first The energy released by a single fission of a nuclide The total number of nuclides, For core power, and For the first The exponential fitting parameters of the thermal neutron fission function of each nuclide. For the first The total number of exponential fitting parameters corresponding to each nuclide. For example, in some embodiments, the correction factor... and energy Calculated using existing nuclear energy engineering standard documents. It should be noted that in the calculation expression for the total decay heat power of the spent pool before the accident... The value of can be non-integer, thus corresponding to the actual refueling interval in the nuclear power plant. For example, the fuel assemblies in the reactor are refueled every 1.5 years in a nuclear power plant. At that time, The values ​​in the above calculation expression include 1.5, 3, 4.5, and 6. The above embodiments combine specific calculation formulas with parameters... Different values ​​can accurately reflect the actual age of spent fuel assemblies stored in the spent fuel pool, thus providing more accurate and realistic total decay heat power of the spent fuel pool before the accident for subsequent calculations.

[0042] Reference Figure 2 In some embodiments, step S3 further includes the following sub-steps. Step S31 is to calculate the decay heat of spent fuel and the total energy required for boiling at each accident moment through time-step iteration based on the number of newly added spent fuel assemblies, spent fuel pool data, and the total decay heat power of the spent fuel pool before the accident. Step S32 is to sequentially determine whether the decay heat of spent fuel and the total energy required for boiling at each accident moment are equal. If the determination result is yes, then the current accident moment is taken as the boiling moment. It can be understood that when the decay heat of spent fuel and the total energy required for boiling are equal, it means that the liquid in the spent fuel pool has absorbed enough heat and is at the moment of transition from liquid to gas, i.e., the boiling moment.

[0043] Understandably, the total number of incident moments within the total duration of an accident can be set, thus varying the duration between adjacent incident moments and ensuring that none of the incident moments are boiling points. Therefore, continue to refer to... Figure 2 In some embodiments, step S3 further includes step S33. Specifically, step S33 involves taking the accident time point where the difference between the spent fuel decay heat and the total energy required for boiling is not equal at all accident times. The accident time point where the difference is the smallest positive value is taken as the first time point, and the accident time point where the difference is the largest negative value is taken as the second time point. The boiling time point is then calculated based on the first and second time points. For example, in some embodiments, based on the first and second time points, interpolation, the number of newly added spent fuel components, the spent fuel pool data, and the total decay heat power of the spent fuel pool before the accident can be used to further calculate and obtain the time point between the first and second time points where the spent fuel decay heat and the total energy required for boiling are equal, thus ensuring the accuracy and precision of the boiling time calculation.

[0044] Regarding the aforementioned spent fuel decay heat, in some embodiments, the spent fuel pool is equipped with a spent fuel pool grid and fuel transport channels. The spent fuel pool data includes the spent fuel pool length, width, and bottom height; the fuel transport channel length, width, and height; the grid volume; the saturated density of the liquid in the spent fuel pool; and the total volume of the spent fuel assemblies in the spent fuel pool. Therefore, the corresponding expression for calculating the spent fuel decay heat is:

[0045] ,in,

[0046] ,

[0047] ,

[0048] ,

[0049] ,

[0050] ,

[0051] ,

[0052] ,

[0053] ,

[0054] In the formula and The time of the accident and the moment of the accident The corresponding decay heat of spent fuel, The spent fuel pool already contained fuel from before the accident. The total decay heat power of the spent fuel assembly within the year corresponds to the pre-accident total decay heat power of the spent fuel pool. This is the duration of the reactor shutdown. For the moment of the accident The number of newly added spent fuel assemblies, This represents the total number of fuel assemblies in the reactor during a single refueling operation. For the reactor during an accident No. The correction factor for neutron capture of individual nuclides. For the first The energy released by a single fission of a nuclide The total number of nuclides, For core power, and For the first The exponential fitting parameters of the thermal neutron fission function of each nuclide. For the first The total number of exponential fitting parameters corresponding to each nuclide. For saturated density, The length of the spent fuel pool Width of the spent fuel pool This refers to the bottom height of the spent fuel pool. For the volume of the lattice, The total volume of the component. For channel length, For channel width, For the channel height, For the moment of the accident The corresponding flow rate at the breach.

[0055] Accordingly, regarding the total energy required for boiling mentioned above, in some embodiments, the spent fuel pool is also equipped with a spent fuel pool grid and fuel transport channels. The spent fuel pool data includes the length, width, and bottom height of the spent fuel pool; the length, width, and height of the fuel transport channels; the grid volume of the spent fuel pool; the saturated density of the liquid in the spent fuel pool; and the total volume of the spent fuel components in the spent fuel pool. Therefore, the corresponding expression for calculating the total energy required for boiling is:

[0056] ,in,

[0057] ,

[0058] ,

[0059] ,

[0060] ,

[0061] ,

[0062] In the formula For the moment of the accident The total energy required for boiling. For saturated density, The length of the spent fuel pool Width of the spent fuel pool This refers to the bottom height of the spent fuel pool. For the volume of the lattice, The total volume of the component. For channel length, For channel width, For the channel height, For the moment of the accident The liquid level height.

[0063] In step S3 of some embodiments, the water replenishment start time is the time point corresponding to the liquid level in the spent fuel pool being equal to the water replenishment point height, and the water replenishment end time is the time point corresponding to the liquid level in the spent fuel pool being equal to the ineffective point height. The total required water replenishment volume is the water replenishment volume corresponding to the final accident time corresponding to the total duration of the accident. It should be noted that the water replenishment point height is the liquid level in the spent fuel pool at which operators need to replenish the water; that is, when the liquid level in the spent fuel pool is lower than the water replenishment point height, operators need to replenish the spent fuel pool. Correspondingly, the ineffective point height is the dangerous liquid level in the spent fuel pool, and the ineffective point height is lower than the water replenishment point height. That is, when the liquid level in the spent fuel pool is not higher than the ineffective point height, it is determined that replenishing the spent fuel pool cannot alleviate the accident. Therefore, the water replenishment start time and water replenishment end time can effectively determine the time period during which operators can perform effective replenishment operations, i.e., the time window for personnel intervention. Furthermore, the water replenishment volume is the total amount of liquid evaporated from the spent fuel pool from the time of the accident to the current time. Therefore, the total required water replenishment can determine the total amount of liquid evaporated from the spent fuel pool during the total duration of the accident, which helps to determine the feasibility of water replenishment by operators and to analyze subsequent analysis operations such as the amount of water replenishment per unit time.

[0064] As can be seen from the above, the liquid level is one of the key points in the calculation. Therefore, in some embodiments, when the spent fuel pool is equipped with a spent fuel pool grid and fuel transport channels, and the spent fuel pool data includes the length, width, and bottom height of the spent fuel pool, the length, width, and height of the fuel transport channels, the grid volume of the spent fuel pool, the saturated density and latent heat of vaporization of the liquid in the spent fuel pool, and the total volume of the spent fuel assemblies in the spent fuel pool, the expression for calculating the liquid level is:

[0065] ,in,

[0066] ,

[0067] ,

[0068] ,

[0069] ,

[0070] ,

[0071] ,

[0072] ,

[0073] ,

[0074] ,

[0075] In the formula For the moment of the accident The total energy required for boiling. For saturated density, The length of the spent fuel pool Width of the spent fuel pool This refers to the bottom height of the spent fuel pool. For the volume of the lattice, The total volume of the component. For channel length, For channel width, For the channel height, For the moment of the accident The liquid level height, This is the latent heat of vaporization.

[0076] Furthermore, in some embodiments, the formula for calculating the water replenishment volume is:

[0077] ,

[0078] In the formula and The time of the accident and the moment of the accident The corresponding water replenishment volume. It should be noted that in this calculation expression... The specific calculation method can be found in the corresponding calculation expression above, and will not be repeated here.

[0079] It should be noted that the above calculations are performed using a time-step iteration method, therefore it is necessary to use the initial moment of the accident. The corresponding data serves as the basis for iterative data at each subsequent accident moment. Specifically, in some embodiments, the wastewater pool data also includes the initial moment. Corresponding liquid level height Then at the initial time The corresponding formula for calculating the total energy required for boiling is: ,in,

[0080] ,

[0081] ,

[0082] .

[0083] In addition, the initial time The corresponding formula for calculating the decay heat of spent fuel is:

[0084] ,in,

[0085] ,

[0086] .

[0087] Furthermore, the above embodiments all include the time of the accident. Corresponding break flow Dynamic leakage modeling is employed. For example, in some embodiments, the wastewater data also includes the breach height and initial liquid level height, as well as the breach flow rate. The calculation expression is:

[0088] ,in,

[0089] ,

[0090] In the formula, The height of the breach. This is the total resistance coefficient of the fuel transport route. For the moment of the accident The liquid level height, This represents the enthalpy of the spent fuel pool under saturation conditions. The enthalpy of the spent fuel pool at the initial water temperature is given. The initial moment of the accident. Initial time The corresponding initial liquid level height. Where there is no breach in the spent fuel pool, the breach height is the liquid level height at the current moment.

[0091] Understandably, the above-mentioned setting of the break height is determined by the break flow rate. When applied to the above embodiments, it can accommodate situations where the spent fuel pool has a breach, causing the liquid level in the spent fuel pool to begin to drop before the liquid boils upon heating, and situations where the spent fuel pool does not have a breach, allowing the liquid level in the spent fuel pool to remain constant before the liquid boils upon heating. This allows for a more accurate assessment of the actual scenario and the corresponding total energy required for spent fuel decay heat and boiling, which in turn provides strong support for calculating the start and end times of subsequent water replenishment and the total required water replenishment volume.

[0092] It should be noted that this application does not limit the flow rate at the breach. The calculation method, in some embodiments, involves the flow rate at the break point. The calculation is performed using a preset static liquid level drop curve. For example, a static liquid level drop curve is set based on the maximum conservative leakage rate, and each data point in the static liquid level drop curve corresponds to the breach flow rate at each accident moment. Thus, the accident moment is determined from the static liquid level drop curve. The corresponding data points are used to obtain the corresponding breach flow. .

[0093] The processing details of the method 100 for calculating the time that can be intervened by personnel have been explained above. The following is a further explanation of the method 100 for calculating the time that can be intervened by personnel through a specific example.

[0094] In one example, the accident occurred during reactor refueling, after the reactor had been shut down for 150 hours. The total duration of the incident is 72 hours. Currently, the spent fuel is being unloaded, and there are no reports of spent fuel pool liquid leaks. However, any potential spent fuel pool liquid leaks include spent fuel pool ruptures. Furthermore, the initial time of the incident... 69 spent fuel assemblies have been unloaded. The total number of spent fuel assemblies in the spent fuel pool is 157. The reactor power is 4040 MWt. Furthermore, the spent fuel pool already contains spent fuel assemblies from the previous 15 years. Then the initial time can be calculated. The corresponding decay heat of spent fuel is 16.027 MW, and at the initial time... The total energy required for boiling is 2.6E+0.5 MJ. Subsequently, based on the initial time... Determine the time points corresponding to each accident and calculate the corresponding spent fuel decay heat and the total energy required for boiling. For example, determine the accident time... Set as the distance from the initial time The time point 1 hour later is And calculate the time of the accident. Corresponding decay heat of spent fuel Less than the total energy required for boiling. Then determine the time of the accident. The liquid in the spent fuel pool had not yet boiled, and the time step iteration continued. When the accident time was calculated... exist Then determine the time of the accident. The boiling point is then determined. Next, from the boiling point to the final accident point (t=72h), the corresponding liquid level is calculated for each accident point to determine the start and end times of water replenishment, as well as the total required water replenishment volume.

[0095] In another example, the accident occurred during reactor refueling, after the reactor had been shut down for 150 hours. The total duration of the incident is 72 hours. It is currently in the process of unloading spent fuel, and there is a liquid leak from the spent fuel pool. Furthermore, the initial time of the incident... 69 spent fuel assemblies have been unloaded. The total number of spent fuel assemblies in the spent fuel pool is 157. The reactor power is 4040 MWt. Furthermore, the spent fuel pool already contains spent fuel assemblies from the previous 15 years. Then the initial time can be calculated. Corresponding break flow That is, the liquid leakage flow rate caused by the liquid leak event is 225m³. 3 / s and the calculated initial time The total energy required for boiling is 2.6E+0.5 MJ. Subsequently, based on the initial time... Determine the time points corresponding to each accident and calculate the corresponding spent fuel decay heat and the total energy required for boiling. For example, determine the accident time... Set as the distance from the initial time The time point 1 hour later is And calculate the time of the accident. Corresponding decay heat of spent fuel It is 5.7E+02 and less than the total energy required for boiling. Then determine the time of the accident. The liquid in the spent fuel pool had not yet boiled, and the time step iteration continued. When the accident time was calculated... exist Then determine the time of the accident. The boiling point is then determined. Next, from the boiling point to the final accident point (t=72h), the corresponding liquid level is calculated for each accident point to determine the start and end times of water replenishment, as well as the total required water replenishment volume.

[0096] It should be noted that the calculated total water demand, water supply start time, and water supply termination time can be subsequently used for probabilistic safety analysis of nuclear power plants. For example, refer to... Figure 3The nuclear power plant 30 includes an in-containment refueling water storage tank 31 (IRWST), a reactor cavity 32, a fuel transfer channel 33 (FTC), a passive containment cooling system water storage tank 34 (PCS Tank), a spent fuel pool 35 (SFP), a chemical waste pit 36 ​​(CWP), and a chemical laundry pit 37 (CLP). Among these, the chemical waste pit 36 ​​and the chemical laundry pit 37 are water tanks with makeup water functions, capable of replenishing the spent fuel pool 35 and thus raising the liquid level within it. To address this, the total liquid storage volume of all pools was calculated and compared with the total required makeup water volume of the spent fuel pool 35 under a given scenario. This determined whether the total liquid storage volume could meet the total required makeup water volume, thus yielding the safety analysis results for the nuclear power plant 30 under this scenario. Furthermore, the makeup water start and end times could be further correlated with the probability of human error and the makeup water rate of the pools, thereby further confirming the safety probability of the nuclear power plant 30 under additional factors. The probability of human error corresponds to human operations, including starting standby pumps and emergency makeup water.

[0097] In summary, the method for calculating time of intervention by personnel 100 can adapt to various accident scenarios in nuclear power plants through the construction of relevant calculation expressions, such as LOCA accidents corresponding to liquid leakage in spent fuel pools, and can obtain accurate liquid level heights at various time points, thereby effectively determining the critical point of spent fuel assembly exposure, which is beneficial for subsequent safety probability analysis, such as quantitative analysis of risks related to spent fuel assembly exposure.

[0098] An embodiment of this application also proposes a method such as Figure 4 The system 200 for calculating the time available for intervention in a wastewater accident scenario (hereinafter referred to as the system 200 for calculating the time available for intervention) is shown. Figure 4 The human-interventionable time calculation system 200 may include an internal communication bus 21, a processor 22, a read-only memory (ROM) 23, a random access memory (RAM) 24, and a communication port 25. When applied to a personal computer, the human-interventionable time calculation system 200 may also include a hard disk 26.

[0099] The internal communication bus 21 enables data communication between components of the human intervention time calculation system 200. The processor 22 can perform judgments and issue prompts. In some embodiments, the processor 22 may consist of one or more processors. The communication port 25 enables data communication between the human intervention time calculation system 200 and external systems. In some embodiments, the human intervention time calculation system 200 can send and receive information and data from a network via the communication port 25.

[0100] The human-interventionable time-computing system 200 may also include different forms of program storage units and data storage units, such as hard disk 26, read-only memory (ROM) 23, and random access memory (RAM) 24, capable of storing various data files used for computer processing and / or communication, as well as possible program instructions executed by processor 22. The processor executes these instructions to implement the main part of the method. The results of processor processing are transmitted to the user equipment via a communication port and displayed on the user interface.

[0101] In addition, this application also proposes a computer-readable medium storing computer program code, which, when executed by a processor, implements the above-mentioned method for calculating the time of human intervention in a low-energy-density battery accident scenario.

[0102] The basic concepts have been described above. Obviously, for those skilled in the art, the above disclosure is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0103] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0104] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of the present application requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of the single embodiments disclosed above.

[0105] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of scope in some embodiments of this application are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

[0106] Some aspects of this application can be executed entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.), or by a combination of hardware and software. The aforementioned hardware or software may be referred to as a "data block," "module," "engine," "unit," "component," or "system." The processor may be one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DAPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, or combinations thereof. Furthermore, aspects of this application may manifest as computer products residing in one or more computer-readable media, including computer-readable program code. For example, computer-readable media may include, but are not limited to, magnetic storage devices (e.g., hard disks, floppy disks, magnetic tapes, etc.), optical discs (e.g., compressed CDs, digital multifunction DVDs, etc.), smart cards, and flash memory devices (e.g., cards, sticks, key drives, etc.).

[0107] A computer-readable medium may contain a propagated data signal containing computer program code, for example, on baseband or as part of a carrier wave. This propagated signal may take various forms, including electromagnetic, optical, and so on, or suitable combinations thereof. A computer-readable medium can be any computer-readable medium other than a computer-readable storage medium, which can be connected to an instruction execution system, apparatus, or device to enable communication, propagation, or transmission of a program for use. The program code located on the computer-readable medium can be propagated through any suitable medium, including radio, cable, fiber optic cable, radio frequency signals, or similar media, or any combination of the above media.

[0108] Although this application has been described with reference to specific embodiments, those skilled in the art should recognize that the above embodiments are only used to illustrate this application, and various equivalent changes or substitutions can be made without departing from the spirit of this application. Therefore, any changes or modifications to the above embodiments within the essential spirit of this application will fall within the scope of the claims of this application.

Claims

1. A method for calculating the time of human intervention in a spent fuel pool accident scenario, applicable to spent fuel pools located in nuclear power plants, wherein the nuclear power plant includes a reactor, the spent fuel pool is suitable for storing spent fuel assemblies, the spent fuel pool is provided with spent fuel pool racks and fuel transport channels, and the spent fuel assemblies include fuel assemblies removed from the reactor, characterized in that, The method for calculating the time available for intervention by personnel includes: The refueling data of the nuclear power plant is obtained, and the total decay heat power of the spent fuel pool before the accident is calculated based on the refueling data. The refueling data includes the storage years of the spent fuel assemblies in the spent fuel pool, the shutdown time of the reactor, the core power of the reactor, and the number of fuel assemblies removed from the reactor during a single refueling. Acquire the spent fuel pool data and the number of newly added spent fuel assemblies at each accident moment within the total accident duration. The spent fuel pool data includes the spent fuel pool length, spent fuel pool width, and spent fuel pool bottom height; the fuel transport channel length, channel width, and channel height; the spent fuel pool grid volume; the saturated density of the liquid in the spent fuel pool; and the total volume of the spent fuel assemblies in the spent fuel pool. The boiling moment is obtained by iterative calculation using time steps based on the number of newly added spent fuel assemblies, the spent pool data, and the total decay heat power of the spent pool before the accident. The start time, end time, and total required water replenishment are calculated iteratively over time steps based on the boiling time, the number of newly added spent fuel assemblies, the spent fuel pool data, and the total decay heat power of the spent fuel pool before the accident.

2. The method for calculating the time for human intervention in a spent fuel pool accident scenario as described in claim 1, characterized in that, The formula for calculating the total decay heat power of the waste pool before the accident is as follows: ,in, ， ， In the formula The storage life of the spent fuel assembly. The spent fuel pool already contained fuel prior to the accident. The total decay heat power of the spent fuel assembly within the year corresponds to the total decay heat power of the spent pool before the accident. The duration of the reactor shutdown is mentioned. The quantity of material changed in a single operation. The total number of fuel assemblies in the reactor. In the reactor Time of the first The correction factor for neutron capture of individual nuclides. For the first The energy released by a single fission of a nuclide The total number of nuclides, The core power is... and For the first The exponential fitting parameters of the thermal neutron fission function of each nuclide. For the first The total number of exponential fitting parameters corresponding to each nuclide.

3. The method for calculating the time for human intervention in a spent fuel pool accident scenario as described in claim 1, characterized in that, The step of calculating the boiling moment through time-step iteration based on the number of newly added spent fuel assemblies, the spent pool data, and the total decay heat power of the spent pool before the accident further includes: Based on the number of newly added spent fuel assemblies, the spent fuel pool data, and the total decay heat power of the spent fuel pool before the accident, the spent fuel decay heat and the total energy required for boiling at each of the accident moments are calculated through time step iterations. The decay heat of spent fuel and the total energy required for boiling are determined sequentially at each of the accident times. If the determination result is yes, the current accident time is taken as the boiling time.

4. The method for calculating the time for human intervention in a spent fuel pool accident scenario as described in claim 3, characterized in that, The step of calculating the boiling moment through time step iteration based on the number of newly added spent fuel assemblies, the spent fuel pool data, and the total decay heat power of the spent fuel pool before the accident also includes: When the heat of decay of spent fuel and the total energy required for boiling are not equal at all the time points of the accident, the time point at which the difference between the heat of decay of spent fuel and the total energy required for boiling is the smallest positive value is taken as the first time point, and the time point at which the difference between the heat of decay of spent fuel and the total energy required for boiling is the largest negative value is taken as the second time point. The boiling time is then calculated based on the first time point and the second time point.

5. The method for calculating the time for human intervention in a spent fuel pool accident scenario as described in claim 3, characterized in that, The calculation expression for the decay heat of spent fuel is as follows: ,in, ， ， ， ， ， ， ， ， In the formula and The time of the accident and the moment of the accident The corresponding decay heat of spent fuel, The spent fuel pool already contained fuel prior to the accident. The total decay heat power of the spent fuel assembly within the year corresponds to the total decay heat power of the spent pool before the accident. This is the duration of the reactor shutdown. For the moment of the accident The number of newly added spent fuel assemblies, This refers to the total number of fuel assemblies in the reactor during a single refueling operation. For the reactor at the time of the accident No. The correction factor for neutron capture of individual nuclides. For the first The energy released by a single fission of a nuclide The total number of nuclides, For core power, and For the first The exponential fitting parameters of the thermal neutron fission function of each nuclide. For the first The total number of exponential fitting parameters corresponding to each nuclide. The saturation density is... The length of the spent fuel pool is... The width of the spent fuel pool, The bottom height of the spent fuel pool is [height]. For the volume of the lattice, The total volume of the component. The length of the channel. The width of the channel. The height of the channel. For the moment of the accident The corresponding break flow rate, For the moment of the accident The liquid level height.

6. The method for calculating the time for human intervention in a spent fuel pool accident scenario as described in claim 3, characterized in that, The formula for calculating the total energy required for boiling is: ,in, ， ， ， ， ， In the formula For the moment of the accident The total energy required for boiling, The saturation density is... The length of the spent fuel pool is... The width of the spent fuel pool, The bottom height of the spent fuel pool is [height]. For the volume of the lattice, The total volume of the component. The length of the channel. The width of the channel. The height of the channel. For the moment of the accident The corresponding break flow rate, The enthalpy of the spent fuel pool under saturation conditions. The enthalpy of the spent fuel pool at the initial water temperature is given. For the moment of the accident The liquid level height.

7. The method for calculating the time for human intervention in a spent fuel pool accident scenario as described in claim 1, characterized in that, The water replenishment start time is the time point when the liquid level in the spent fuel pool is equal to the water replenishment point height, and the water replenishment end time is the time point when the liquid level in the spent fuel pool is equal to the invalid point height. The total required water replenishment volume is the water replenishment volume corresponding to the final accident time corresponding to the total duration of the accident.

8. The method for calculating the time for human intervention in a spent fuel pool accident scenario as described in claim 7, characterized in that, The spent fuel pool is equipped with a spent fuel pool grid and a fuel transport channel. The spent fuel pool data includes the length, width, and bottom height of the spent fuel pool; the length, width, and height of the fuel transport channel; the grid volume of the spent fuel pool; the saturated density and latent heat of vaporization of the liquid in the spent fuel pool; and the total volume of the spent fuel assemblies in the spent fuel pool. The expression for calculating the liquid level height is as follows: ,in, ， ， ， ， ， ， ， ， ， In the formula, The saturation density is... The length of the spent fuel pool is... The width of the spent fuel pool, The bottom height of the spent fuel pool is [height]. For the volume of the lattice, The total volume of the component. The length of the channel. The width of the channel. The height of the channel. For the moment of the accident The corresponding break flow rate, The latent heat of vaporization, For the moment of the accident The liquid level height, and The time of the accident and the moment of the accident The corresponding decay heat of spent fuel, The spent fuel pool already contained fuel prior to the accident. The total decay heat power of the spent fuel assembly within the year corresponds to the total decay heat power of the spent pool before the accident. For the moment of the accident The number of newly added spent fuel assemblies, This refers to the total number of fuel assemblies in the reactor during a single refueling operation. For the reactor at the time of the accident No. The correction factor for neutron capture of individual nuclides. For the first The energy released by a single fission of a nuclide The total number of nuclides, For core power, and For the first The exponential fitting parameters of the thermal neutron fission function of a nuclide.

9. The method for calculating the time for human intervention in a spent fuel pool accident scenario as described in claim 8, characterized in that, The formula for calculating the water replenishment volume is: ， In the formula and The time of the accident and the moment of the accident The corresponding water replenishment volume.

10. The method for calculating the time for human intervention in a spent fuel pool accident scenario as described in claim 5, 6, or 8, characterized in that, The wastewater data also includes the break height and initial liquid level, and the break flow rate. The calculation expression is: ,in, ， In the formula The height of the breach, The total resistance coefficient of the fuel transport channel is given. For the moment of the accident The liquid level height of the liquid, The enthalpy of the spent fuel pool under saturation conditions. The enthalpy of the spent fuel pool at the initial water temperature is given. The initial moment of the accident. Wherein, when there is no breach in the spent fuel pool, the breach height is the liquid level height at the current moment.

11. The method for calculating the time for human intervention in a spent fuel pool accident scenario as described in claim 5, 6, or 8, characterized in that, Break flow It is calculated using a preset static liquid level drop curve.

12. A system for calculating the time of human intervention in a spent fuel pool accident scenario, comprising: Memory is used to store instructions that can be executed by the processor; And a processor for executing the instructions to implement the method for calculating the time for human intervention in a spent fuel pool accident scenario as described in any one of claims 1-11.

13. A computer-readable medium storing computer program code, which, when executed by a processor, implements the method for calculating the time of human intervention in a low-energy pool accident scenario as described in any one of claims 1-11.

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