JP7494131B2 - LIQUID LEVEL CALCULATION METHOD, LIQUID LEVEL CALCULATION DEVICE, AND PROGRAM - Google Patents

Description

The present disclosure relates to a liquid level calculation method, a liquid level calculation device, and a program.

In the steam generator of a nuclear power plant, pressure taps are installed above and below the range that includes the cooling water level in the downcomer section, and the water level is measured from the differential pressure measured at the upper and lower pressure tap positions (Patent Document 1). Meanwhile, analysis codes for nuclear power plants calculate the water level based on the volume of water in the steam generator.

Japanese Patent Application Laid-Open No. 60-13287

The water level calculations using the analysis code differ from the method and principle of measuring water level in an actual machine, so there is often an error with the water level measured in the actual machine. There is a demand for a method to calculate water level in the same way as in the actual machine.

The present disclosure provides a liquid level calculation method, a liquid level calculation device, and a program that can solve the above problems.

According to an embodiment of the present disclosure, a liquid level calculation method is a method for calculating the pressure of a liquid at a predetermined measurement position of a vessel containing liquid, the method including the steps of: acquiring an analysis value of an average pressure for each of a plurality of sections when the vessel is divided into the plurality of sections; selecting the analysis value of a target section, which is the section including the measurement position among the plurality of sections; and calculating the pressure at the measurement position by correcting the average pressure of the target section based on the height of the measurement position relative to the height of the entire target section, by using the pressure calculation method to calculate the pressure at the measurement position by assuming the vessel as the pressure vessel, and calculating the pressure at the installation position of the lower pressure tap by using the pressure calculation method to calculate the liquid level of the pressure vessel from the pressure difference between the installation position of the upper pressure tap and the installation position of the lower pressure tap. The pressure vessel is a steam generator or a pressurizer.

According to one embodiment of the present disclosure, in the step of calculating the pressure at the measurement position, where Pvol is the average pressure of the target section, ΔP is the pressure difference between the upper and lower ends of the target section, a is the height direction distance from the upper end of the target section to the measurement position, h is the height of the target section, and Pt is the pressure at the measurement position, the pressure Pt at the measurement position is calculated as Pt = Pvol + ΔP × ((a÷h)-0.5).

According to one embodiment of the present disclosure, the vessel is a pressure vessel, and in the step of acquiring the analytical value of the average pressure, an analytical value of the cooling water pressure for each volume when the pressure vessel is divided into a plurality of volumes is acquired, calculated by an analysis code that simulates the behavior of the nuclear power plant, and in the step of selecting, the volume including an installation position of a pressure tap for measuring liquid level in the pressure vessel is selected as the target partition, and in the step of calculating the pressure at the measurement position, the average pressure of the target partition calculated by the analysis code is corrected to calculate the pressure at the installation position of the pressure tap.

According to one embodiment of the present disclosure , a liquid level calculation device is a pressure calculation device that calculates the pressure of the liquid at a predetermined measurement position of a container containing the liquid, and includes: an acquisition unit that acquires an analytical value of an average pressure for each compartment when the container is divided into a plurality of compartments; a selection unit that selects the analytical value of a target compartment which is the compartment including the measurement position among the plurality of compartments; and a calculation unit that calculates the pressure at the measurement position by correcting the average pressure of the target compartment based on the height of the measurement position relative to the height of the entire target compartment; a pressure calculation unit that calculates the pressure at the installation position of an upper pressure tap and the pressure at the installation position of a lower pressure tap for an upper pressure tap and a lower pressure tap provided in a pressure vessel of a nuclear power plant using the pressure calculation device, with the vessel as the pressure vessel; and a liquid level calculation unit that calculates the liquid level of the pressure vessel from the differential pressure between the pressure at the installation position of the upper pressure tap and the pressure at the installation position of the lower pressure tap.

According to one embodiment of the present disclosure, a program causes a computer to execute a pressure calculation process for calculating the pressure at the installation position of an upper pressure tap and a lower pressure tap provided in a pressure vessel equipped in a nuclear power plant, the pressure at the installation position of the upper pressure tap being calculated at a predetermined measurement position of a vessel containing liquid, the pressure calculation process including the steps of: acquiring an analytical value of an average pressure for each of the compartments when the vessel is divided into a plurality of compartments; selecting the analytical value of a target compartment which is the compartment that includes the measurement position among the plurality of compartments; and calculating the pressure at the measurement position by correcting the average pressure of the target compartment based on the height of the measurement position relative to the height of the entire target compartment, by executing the vessel as the pressure vessel; calculating the pressure at the installation position of the lower pressure tap using the pressure calculation process by using the vessel as the pressure vessel; and calculating the liquid level of the pressure vessel from the differential pressure between the pressure at the installation position of the upper pressure tap and the pressure at the installation position of the lower pressure tap.

The above-mentioned pressure calculation method, liquid level calculation method, pressure calculation device, and program allow pressure or liquid level to be calculated in the same way as in an actual machine.

FIG. 1 is a functional block diagram illustrating an example of a water level calculation device according to an embodiment. 1 is a schematic diagram of a pressurized water nuclear power plant. FIG. 13 is a diagram illustrating a method for calculating a water level according to the embodiment. FIG. 11 is a diagram showing an example of a processing flow of a water level calculation method according to an embodiment. 10A to 10C are diagrams illustrating the effects of a water level calculation method according to an embodiment. FIG. 2 is a diagram illustrating an example of a hardware configuration of a water level calculation device according to an embodiment.

<Embodiment>
(System configuration)
The water level calculation device of the present disclosure will be described below with reference to FIGS. 1 to 6. FIG.
The water level calculation device 10 shown in FIG. 1 calculates the water level of the steam generator 4 shown in FIG. 2 by using a program for analyzing a nuclear reactor called an analysis code. FIG. 2 shows an outline of a pressurized water nuclear power plant 1. The nuclear power plant 1 includes a nuclear reactor 2, a pressurizer 3, a steam generator 4, a primary cooling loop 5, and a reactor containment vessel 7. The nuclear reactor 2 includes a reactor vessel 8, fuel rods 9a, control rods 9b, and other reactor internal structures (not shown). The primary cooling loop 5 forms a flow path for circulating the primary cooling water between the reactor vessel 8 and the steam generator 4. The primary cooling loop 5 includes a primary cooling pump 6 for circulating the primary cooling water. The pressurizer 3 pressurizes the inside of the primary cooling loop 5. The steam generator 4 exchanges heat between the secondary cooling water flowing through the secondary equipment including a turbine and the like and the primary cooling water circulating through the primary cooling loop 5 to heat the secondary cooling water and generate steam. The reactor containment vessel 7 houses the reactor 2, the primary cooling loop 5, the pressurizer 3, and the steam generator 4. As will be described below, the water level calculation device 10 uses pressure calculation values for each volume in the steam generator 4 obtained by an analysis code to calculate the water level of the secondary cooling water in the steam generator 4 based on the same principle as water level measurement in an actual machine.

The water level calculation device 10 includes an input receiving unit 11, a control unit 12, a storage unit 13, and an output unit 14. The control unit 12 includes a water level calculation unit 121. The storage unit 13 stores an analysis code 131.
The input receiving unit 11 receives input of various information necessary for water level calculation.
The control unit 12 controls the calculation process of the water level. The control unit 12 calculates the pressure for each volume of the steam generator 4 using an analysis code 131 such as RELAP5 that simulates the behavior of the nuclear plant 1. The analysis code 131 is a program that simulates the behavior of the nuclear plant 1, and analyzes the operation of the nuclear plant 1 when various events such as abnormalities occur, and calculates various quantities during operation. In the analysis of the nuclear plant 1, various types of analysis codes are used depending on the purpose. For example, the analysis code 131 called RELAP5 can be used to analyze the flow of cooling water in the cooling system of the nuclear facility 1. In this analysis, the pressure, temperature, density, etc. of the cooling water for each volume are calculated. The volume of the steam generator 4 will be described with reference to FIG. 2. A volume is each section formed by dividing the steam generator 4 into predetermined areas, and is a calculation unit when the analysis code 131 analyzes the flow of cooling water and steam in the steam generator 4. The sections 4a and 4b in FIG. 2 are examples of volumes. The analysis code 131 analyzes the characteristics of the cooling water, etc. of the volume for each volume. The analysis code 131 calculates the pressure, temperature, flow rate, density, and volume of the cooling water, and the density and volume of the water vapor for each volume. The pressure of the volume calculated by the analysis code 131 is the average pressure of the volume.

In addition, the analysis code 131 calculates the volume of the secondary cooling water present in the steam generator 4 for the secondary cooling water circulating between the secondary equipment, and calculates the water level of the steam generator 4 based on this volume. For example, if the volume between the upper pressure tap T1 and the lower pressure tap T2 of the steam generator 4 is 100, and the volume of the cooling water present between the upper pressure tap T1 and the lower pressure tap T2 of the steam generator 4 at a certain point in time is 80, the analysis code 131 calculates the water level of the steam generator 4 to be 80%.

The water level calculation unit 121 calculates the water level of the steam generator 4 using a method different from the volume-based water level calculation possessed by the analysis code 131. Here, a method for measuring the water level in an actual machine will be described. T1 and T2 in FIG. 2 are the installation positions of pressure taps for measuring the water level in an actual machine. In an actual machine, an upper tap is provided at position T1 and a lower tap at position T2, and the water level is measured from the differential pressure between the pressure at the upper tap position T1 and the pressure at the lower tap position T2. The method for measuring the water level from the differential pressure is publicly known. In the simplest example, water is stored in a container not shown, and an upper pressure tap and a lower pressure tap are provided at positions above and below the water surface (the upper pressure tap is t1 and the lower pressure tap is t2). In this case, if the pressure at the upper tap position t1 is pH, the pressure at the lower tap position t2 is pL, the density of the liquid is ρ, the distance (height) from the lower tap position t2 to the water surface is h, and gravity is g, then the differential pressure Δp = pH - pL = ρgh is established. If ρ and g are known, the distance h from the position t2 to the water surface can be calculated by measuring the differential pressure Δp, and the water level can be calculated by adding h to t2. On the other hand, the analysis code 131 that is generally provided calculates the water level from the volume of the secondary cooling water in the steam generator 4, as described above. When simulating the behavior of the nuclear power plant 1 using the analysis code 131, it is considered that a value closer to the water level measured when the simulated event actually occurs in the actual machine can be obtained if the water level can be calculated using the same principle as the actual water level measurement. For example, when it is desired to simulate the water level fluctuation of the steam generator 4 when a certain event occurs, it is convenient to obtain a calculation result closer to the measurement value of the actual machine.

Furthermore, we will consider the difference between the water level based on the differential pressure (actual machine) and the water level based on the volume (analysis code). For example, if the secondary cooling water is stored in the steam generator 4 in a calm state, the correct water level can be calculated whether the water level is calculated based on the volume or the differential pressure. However, in the steam generator 4, the cooling water is heated by heat exchange, generating steam, and a certain amount of steam is mixed in the liquid phase. Therefore, when calculating the water level of the steam generator 4, an error is likely to occur between the water level calculated based on the volume of the cooling water and the water level calculated by the differential pressure. From this point of view, it is preferable to calculate the water level by the differential pressure, taking into account the gas components contained in the liquid phase, rather than converting the volume of the cooling water into the water level.

The water level calculation unit 121 calculates the water level of the steam generator 4 using the same principle as the actual machine, separately from the water level calculated by the analysis code 131 based on the volume. Specifically, the water level calculation unit 121 calculates the pressure at the upper tap position T1 by correcting the average pressure of the volume including the upper tap position T1 calculated by the analysis code 131. Similarly, the water level calculation unit 121 calculates the pressure at the lower tap position T2 by correcting the average pressure of the volume including the lower tap position T2 calculated by the analysis code 131. Then, the water level of the steam generator 4 is calculated from the differential pressure. In addition, when calculating the pressure at the upper tap position T1 and the lower tap position T2, the pressure is corrected taking into account the water vapor contained in the liquid phase. These calculations will be explained next with reference to FIG. 3.

The storage unit 13 stores various information necessary for calculating the water level of the steam generator 4. For example, the storage unit 13 stores an analysis code 131 such as RELAP5 and the installation position of a tap.
The output unit 14 outputs the water level of the steam generator 4 calculated by the water level calculation unit 121 to a display device, an electronic file, or the like.

Next, a method for calculating the water level of the steam generator 4 by the water level calculation unit 121 will be described with reference to Figure 3. Figure 3 shows a schematic diagram of the downcomer section on the secondary side of the steam generator 4. As described above, the analysis code 131 divides the steam generator 4 into volumes V1, V2, ..., Vi, ..., Vn, and calculates the pressure of each volume. Here, if W1 is the water level, the water level W2 exists in volume V2. Volume V1 is a gas phase mainly composed of steam, and volumes V3 and below (not shown) are liquid phase mainly composed of secondary cooling water.

The upper tap position T1 is the upper tap position of the water level measurement span. The lower tap position T2 is the lower tap position of the water level measurement span. The upper tap position T1 is located in volume V1. The lower tap position T2 is located in volume Vi. For volume Vi, it can be assumed that the difference between the pressure at tap position T2 and the pressure at the upper end (or lower end) of volume Vi is proportional to the distance from the upper end (or lower end) to position T2.

In other words, the pressure at each tap position can be calculated by assuming that there is a pressure gradient corresponding to the head of the secondary cooling water in the volume with respect to the average pressure of the volume calculated by the analysis code. The head ΔP of the volume can be expressed by the following equation (1).
ΔP=(ρω×Vf+ρs×Vg)×h (1)
Here, ρω is the density of the cooling water, Vf is the volume per unit height of the cooling water, ρs is the density of the water vapor contained in the liquid, Vf is the volume per unit height of the vapor, and h is the height of the volume. The inlet of each volume is the upper end (Viu in the case of volume Vi, as shown in the figure), and the outlet is the lower end (Vid in the case of volume Vi, as shown in the figure), and the volume inlet pressure is (Pi), the outlet pressure is (Po), and the volume average pressure is (Pvol). Then, the relationship of the following formulas (2) and (3) is established.
Po-Pi=ΔP (2)
(Po+Pi)/2=Pvol... (3)
From equations (2) and (3), if the pressure at the tap position is Pt, the height of the volume is h, and the distance from the inlet of the volume to the tap position is a, the pressure Pt at the tap position can be calculated using the following equation (4).
Pt = Pvol + ΔP × ((a ÷ h) - 0.5)) ... (4)

(Pressure at upper tap position T1)
Here, the average pressure of volume V1 is Pvol_v1, the density of the cooling water in volume V1 is ρω_v1, the volume of the cooling water per unit height is Vf_v1, the density of the water vapor is ρs_v1, the volume of the water vapor per unit height is Vg_v1, the height of volume V1 is h1, and the distance from the inlet of volume V1 to the upper pressure tap position T1 is a1. Then, from equation (4), the pressure Pt1 at the upper tap position T1 can be calculated by the following equation (5).
Pt1 = Pvol_v1 + (ρω_v1 × Vf_v1 + ρs_v1 × Vg_v1) × h1 × 9.8 × ((a1 ÷ h1) - 0.5) ... (5)
The "9.8" in equation (5) is a conversion coefficient from "kg/ ^m2 " to "Pa". Pvol_v1, ρω_v1, Vf_v1, ρs_v1, and Vg_v1 in equation (5) are values calculated by the analysis code. h1 and a1 in equation (5) are predetermined values. By substituting these values, the pressure at the upper tap position T1 can be calculated from equation (5).

(Pressure at lower tap position T2)
In a similar manner, the pressure at the lower tap position T2 can be calculated. For example, if the average pressure of the volume Vi is Pvol_vi, the density of the cooling water in the volume Vi is ρω_vi, the volume of the cooling water per unit height is Vf_vi, the density of the water vapor is ρs_vi, the volume of the water vapor per unit height is Vg_vi, the height of the volume Vi is h2, and the distance from the inlet of the volume Vi to the upper pressure tap position T2 is a2, the pressure Pt2 at the lower tap position T2 can be calculated by the following formula (6).
Pt2 = Pvol_vi + (ρω_vi × Vf_vi + ρs_vi × Vg_vi) × h2 × 9.8 × ((a2 ÷ h2) - 0.5) ... (6)
The pressure at the lower tap position T2 can be calculated by substituting Pvol_vi, ρω_vi, Vf_vi, ρs_vi, Vg_vi, h2, and a2 into equation (6).

As a result of the above, the pressure Pt1 at the upper tap position and the pressure Pt2 at the lower tap position can be calculated, and the water level in the water level measurement span can be calculated from the differential pressure between these using the same principles as in an actual machine.
The positions of the upper and lower taps are not limited to T1 and T2 in FIG. 3, and it is possible to set the upper and lower pressure taps at any positions and calculate the water level therebetween.

(motion)
FIG. 4 is a diagram showing an example of a process flow of the water level calculation method according to the embodiment.
It is assumed that information regarding the positions of the tap positions T1 to T2 (which volume they belong to (V1, Vi), the distance from the top end of the volume (a1 to a2), and the height of the volume at which the taps are provided (h1 to h2) are registered in advance in the storage unit 13.

First, the analysis code 131 simulates the behavior of the nuclear plant 1 when a disturbance or the like occurs (step S1). The user sets various analysis conditions necessary for simulating disturbances or the like, and instructs the water level calculation device 10 to simulate the nuclear plant 1 and calculate the water level when a disturbance occurs. The input reception unit 11 receives the user's instruction operation and instructs the control unit 12 to perform a simulation using the analysis code 131. The control unit 12 reads out the analysis code 131 from the storage unit 13, sets the analysis conditions set by the user to the analysis code 131, and executes the simulation. The analysis code 131 simulates the progress of events that occur in the nuclear plant 1 when a specified disturbance occurs and the changes in state accompanying the progress of the events, and calculates various quantities such as pressure, temperature, and flow rate in each state. The analysis code outputs time history data of the calculated quantities. For example, the analysis code analyzes the flow state of the liquid phase and the gas phase in the steam generator 4. During this analysis, the average pressure (Pvol) of each volume at each moment, the density (ρω) and volume (Vf) of the cooling water, and the density (ρs) and volume (Vg) of the water vapor are calculated. The calculation of the average pressure Pvol of each volume by the analysis code 131 also takes into account the effect of dynamic pressure due to the flow rate of the cooling water and the effect of water vapor generated by heating. The control unit 12 records the time series data of Pv, ρω, Vf, ρs, and Vg calculated for each volume in the memory unit 13.

Next, the water level calculation unit 121 calculates the pressure at the upper tap position (step S2). For example, the water level calculation unit 121 reads and acquires the time series data calculated in step S1 from the storage unit 13, selects Pvol_v1, ρω_v1, Vf_v1, ρs_v1, and Vg_v1 of the volume including the upper tap position T1 from the data, and calculates the pressure Pt1 at the upper tap position T1 using these selected values, the height h1 of the volume v1 stored in the storage unit 13, the distance a1 from the inlet, and equation (5).

Next, the water level calculation unit 121 calculates the pressure at the lower tap position (step S3). For example, if the water level in the simulated state is included in the water level measurement span, the water level calculation unit 121 reads and acquires the time series data calculated in step S1 from the storage unit 13, selects Pvol_vi, ρω_vi, Vf_vi, ρs_vi, and Vg_vi of the volume Vi that includes the lower tap position T2 from among the data, and calculates the pressure Pt2 at the lower tap position T2 using these selected values, the height h2 of the volume vi stored in the storage unit 13, the distance a2 from the inlet, and equation (6).

Next, the water level calculation unit 121 calculates the water level from the differential pressure between the pressure at the upper tap position and the pressure at the lower tap position (step S4). The water level calculation unit 121 calculates the water level based on the differential pressure between the pressure Pt1 calculated in step S2 and the pressure Pt2 calculated in step S3. Next, the output unit 14 outputs information such as the pressure at the upper tap position, the pressure at the lower tap position, and the water level based on the differential pressure to a display device or the like (step S5). The output unit 14 may also output the water level based on the volume calculated by the analysis code 131.

As described above, according to this embodiment, the water level can be calculated using the same principle as water level measurement in an actual machine. When calculating the water level, the pressure at the upper and lower tap positions is corrected based on the average pressure for each volume calculated by the analysis code. However, in the analysis of the cooling system flow using the analysis code, the effects of the steam pressure caused by the boiling of the cooling water and the dynamic pressure of the cooling water circulation are taken into account, and the average pressure for each volume is calculated, allowing for accurate pressure correction and water level calculation.

Next, an example of the effect of this embodiment will be described. FIG. 5 is a diagram for explaining the effect of the water level calculation method according to the embodiment. FIG. 5 shows the actual water level in a situation where the steam pressure in the steam generator 4 rises, the water level calculated based on the volume when a similar event is simulated by the analysis code 131, and the water level calculated by the method of this embodiment. The vertical axis of the figure shows the water level, and the horizontal axis shows the time. Graph La shows the actual water level. Graph Lv shows the water level based on the volume calculated by the analysis code 131. Graph Lp shows the water level based on the differential pressure calculated by the water level calculation device 10 according to this embodiment. As shown in the figure, the graph Lv showing the water level calculated based on the volume shows the highest water level compared to the water levels of graphs La and Lp when the water level is at its lowest, the graph La of the actual measurement value shows an intermediate water level, and the graph Lp showing the water level calculated by the water level calculation method of this embodiment shows the lowest water level. When some event occurs, the water level of the steam generator 4 when it is at its lowest is important, and it is determined that the lower the water level, the higher the risk. The water level calculated based on the volume (graph Lv) is higher than the actual measurement value (graph La), and if such an analysis result is obtained in advance, it may be determined that the water level will not drop that much even if the event actually occurs. In contrast, the water level (graph Lp) calculated by the water level calculation method of this embodiment is lower than the actual measurement value (graph La). In other words, a conservative analysis result is obtained in the water level calculation based on the differential pressure. This result can be understood as follows. In this example, a situation in which the pressure of the gas phase of the steam generator 4 is rising is simulated. Then, the water surface of the liquid phase is pushed down, and the water vapor in the liquid phase is also crushed. The water level in such a situation is lower than the water level obtained by simply converting the volume of the cooling water into the water level. In the conventional water level calculation based on the volume, the effect of the pressure rise of the gas phase on the water level cannot be reflected in the calculation result, so a water level that is more optimistic than the actual measurement value is obtained. The water level calculation method based on differential pressure allows for more accurate calculations because it uses the average pressure of each analyzed volume, the density and volume of the cooling water and water vapor, and takes into account the downward pressure caused by the increase in gas phase pressure.

As described above, according to this embodiment, the water level is calculated by the same method as the water level measurement in the actual plant, so that the water level can be calculated more accurately than in the past. The water level calculation method of this embodiment can be applied to the calculation of the water level of not only the steam generator 4 but also the pressurizer 3. Specifically, the steam generator 4 in the water level calculation method described with reference to FIG. 3 is read as the pressurizer 3, and the average pressure of the volume corresponding to the upper tap position and the volume corresponding to the lower tap position installed in the pressurizer 3 of the actual plant is calculated by the analysis code 131. Then, the calculated average pressure is corrected by the above method to calculate the pressures at the upper tap position and the lower tap position, and the water level of the pressurizer 3 is calculated by the differential pressure between them.
Furthermore, in the above embodiment, the water level is measured, but the liquid level of any liquid other than water can be calculated in a similar manner.

FIG. 6 is a diagram illustrating an example of a hardware configuration of the water level calculation device according to the embodiment.
The computer 900 includes a CPU 901 , a main memory device 902 , an auxiliary memory device 903 , an input/output interface 904 , and a communication interface 905 .
The water level calculation device 10 described above is implemented in a computer 900. Each of the above-mentioned functions is stored in the auxiliary storage device 903 in the form of a program. The CPU 901 reads the program from the auxiliary storage device 903, loads it in the main storage device 902, and executes the above-mentioned processing in accordance with the program. The CPU 901 also reserves a memory area in the main storage device 902 in accordance with the program. The CPU 901 also reserves a memory area in the auxiliary storage device 903 for storing data being processed in accordance with the program.

A program for realizing all or part of the functions of the water level calculation device 10 may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed to perform processing by each functional unit. The term "computer system" here includes hardware such as an OS and peripheral devices. In addition, if a WWW system is used, the term "computer system" also includes a homepage providing environment (or display environment). In addition, the term "computer-readable recording medium" refers to portable media such as CDs, DVDs, and USBs, and storage devices such as hard disks built into a computer system. In addition, if the program is distributed to a computer 900 via a communication line, the computer 900 that receives the program may expand the program into the main storage device 902 and execute the above processing. In addition, the above program may be for realizing part of the functions described above, and may further be capable of realizing the functions described above in combination with a program already recorded in the computer system.

As described above, several embodiments of the present disclosure have been described, but all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and gist of the invention.

<Additional Notes>
The pressure calculation method, the liquid level calculation method, the pressure calculation device, and the program described in each embodiment can be understood, for example, as follows.

(1) A pressure calculation method according to a first aspect is a method for calculating the pressure of a liquid at a predetermined measurement position in a container containing the liquid, and includes the steps of: acquiring an analysis value of an average pressure for each partition (average pressure for each volume by analysis code 131) when the container is divided into a plurality of partitions (step S1); selecting the analysis value for a target partition (tap positions T1, T2 in FIG. 3), which is the partition that includes the measurement position among the plurality of partitions (steps S2, S3); and calculating the pressure at the measurement position by correcting the average pressure of the target partition based on the height (a1-a2) of the measurement position relative to the height (h1-h2) of the entire target partition (steps S2, S3).
This allows the pressure at the measurement position (the position where the pressure tap is installed) to be calculated by obtaining the pressure per volume of the container containing the liquid.

(2) A pressure calculation method according to a second aspect is the pressure calculation method according to (1), wherein in the step of calculating the pressure at the measurement position, assuming that an average pressure of the target partition is Pvol, a pressure difference between the upper and lower ends of the target partition is ΔP, a distance in a height direction from the measurement position to the upper end of the target partition is a, a height of the target partition is h, and the pressure at the measurement position is Pt,
Pt = Pvol + ΔP × ((a ÷ h) - 0.5)
The pressure Pt at the measurement position is calculated by:
Thus, if the values of Pvol, ΔP, a, and h are obtained, the pressure at the measurement position can be calculated.

(3) A pressure calculation method according to a third aspect is the pressure calculation method of (1) to (2), wherein the vessel is a steam generator of a nuclear power plant, and in the step of acquiring the average pressure, an analytical value of the cooling water pressure for each volume when the steam generator is partitioned into a plurality of volumes is acquired, calculated by an analysis code that simulates the behavior of the nuclear power plant, and in the step of selecting, the node including an installation position of a pressure tap for measuring liquid level in the steam generator is selected as the target partition, and in the step of calculating the pressure at the measurement position, the average pressure of the target partition calculated by the analysis code is corrected to calculate the pressure at the installation position of the pressure tap.
This makes it possible to measure the pressure at the pressure tap installation position using the analysis results obtained by the analysis code in the same manner as in an actual device.

(4) A liquid level calculation method according to a fourth aspect calculates the pressure at the installation position (e.g., T1 or T2) of an upper pressure tap (a pressure tap is a pressure measuring instrument) and a lower pressure tap in a steam generator 4 of a nuclear plant 1 (e.g., T2) of the upper pressure tap by using a pressure calculation method described in any one of (1) to (3), and calculates the liquid level (water level) of the steam generator from the pressure difference between the pressure at the installation position of the upper pressure tap and the pressure at the installation position of the lower pressure tap.
This makes it possible to use the calculation results in the analysis code to calculate the water level in the steam generator 4 in the same manner as in the actual system. Also, based on the upper pressure tap and the lower pressure tap installed at any position, the water level between them can be measured.

(5) A liquid level calculation method according to a fifth aspect calculates the pressures at the installation positions of an upper pressure tap (a pressure tap is a pressure measuring device) and a lower pressure tap in a pressurizer 3 of a nuclear plant 1 using a pressure calculation method described in any one of (1) to (3), and calculates the liquid level (water level) of the pressurizer from the differential pressure between the pressure at the installation position of the upper pressure tap and the pressure at the installation position of the lower pressure tap.
This makes it possible to use the calculation results in the analysis code to calculate the water level in the pressurizer 3 in the same manner as in the actual system.

(6) A pressure calculation device according to a sixth aspect is a pressure calculation device that calculates the pressure of a liquid at a predetermined measurement position in a container containing the liquid, and includes an acquisition unit that acquires an analysis value of an average pressure for each of a plurality of compartments when the container is divided into the plurality of compartments, a selection unit that selects the analysis value of a target compartment that is the compartment that includes the measurement position among the plurality of compartments, and a calculation unit that calculates the pressure at the measurement position by correcting the average pressure of the target compartment based on the height of the measurement position relative to the height of the entire target compartment.

(7) A program according to a seventh aspect causes a computer that calculates the pressure of a liquid at a predetermined measurement position in a container containing the liquid to execute the steps of: acquiring an analytical value of the average pressure for each of a plurality of compartments when the container is divided into the plurality of compartments; selecting the analytical value of a target compartment, which is the compartment that includes the measurement position among the plurality of compartments; and calculating the pressure at the measurement position by correcting the average pressure of the target compartment based on the height of the measurement position relative to the height of the entire target compartment.

Reference Signs List 1: Nuclear plant 2: Nuclear reactor 3: Pressurizer 4: Steam generator 5: Primary cooling loop 6: Primary cooling pump 7: Nuclear reactor containment vessel 8: Nuclear reactor vessel 9a: Fuel rod 9b: Control rod 10: Water level calculation device 11: Input reception unit 12: Control unit 121: Water level calculation unit 13: Memory unit 131: Analysis code 14: Output unit 900: Computer 901: CPU
902: Main memory device 903: Auxiliary memory device 904: Input/output interface 905: Communication interface

Claims (6)

Regarding the upper and lower pressure taps installed in the pressure vessel of a nuclear power plant,
The pressure at the upper pressure tap installation position is
1. A method for calculating a pressure of a liquid at a predetermined measurement location in a container containing said liquid, comprising the steps of:
A step of obtaining an analytical value of an average pressure for each of a plurality of compartments when the container is divided into the plurality of compartments;
selecting the analysis value of a target section, the section including the measurement location, from among the plurality of sections;
calculating a pressure at the measurement location by correcting an average pressure in the target area based on the height of the measurement location relative to the height of the entire target area;
Calculate the pressure by using a pressure calculation method having the following formula:
Calculating the pressure at the installation location of the lower pressure tap using the pressure calculation method by treating the vessel as the pressure vessel;
Calculating the liquid level of the pressure vessel from a pressure difference between the pressure at the installation position of the upper pressure tap and the pressure at the installation position of the lower pressure tap.
How to calculate liquid level. In the step of calculating the pressure at the measurement location,
The average pressure of the target section is Pvol, the pressure difference between the upper and lower ends of the target section is ΔP,
When the distance in the height direction from the upper end of the target section to the measurement position is a, the height of the target section is h, and the pressure at the measurement position is Pt,
Pt = Pvol + ΔP × ((a ÷ h) - 0.5)
Calculate the pressure Pt at the measurement position by
The liquid level calculation method according to claim 1. The vessel is a pressure vessel ,
In the step of acquiring the analytical value of the average pressure, an analytical value of a cooling water pressure for each of a plurality of volumes when the pressure vessel is divided into a plurality of volumes is acquired, the analytical value being calculated by an analysis code that simulates the behavior of the nuclear power plant;
In the selecting step, the volume including the installation position of a pressure tap for measuring a liquid level in the pressure vessel is selected as the target partition;
In the step of calculating the pressure at the measurement position, the average pressure of the target section calculated by the analysis code is corrected to calculate the pressure at the installation position of the pressure tap.
The liquid level calculation method according to claim 1 or 2. The pressure vessel is a steam generator or a pressurizer;
The liquid level calculation method according to any one of claims 1 to 3. A pressure calculation device that calculates a pressure of a liquid at a predetermined measurement position of a container containing the liquid, comprising:
an acquisition unit that acquires an analytical value of an average pressure for each of a plurality of compartments when the container is divided into the plurality of compartments;
A selection unit that selects the analysis value of a target section that is a section including the measurement position among the plurality of sections;
a calculation unit that calculates a pressure at the measurement position by correcting an average pressure of the target section based on a height of the measurement position relative to a height of the entire target section;
A pressure calculation device comprising :
a pressure calculation unit that calculates, for an upper pressure tap and a lower pressure tap provided in a pressure vessel of a nuclear power plant, a pressure at an installation position of the upper pressure tap and a pressure at an installation position of the lower pressure tap by using the pressure calculation device with the vessel as the pressure vessel;
a liquid level calculation unit that calculates a liquid level of the pressure vessel from a pressure difference between a pressure at an installation position of the upper pressure tap and a pressure at an installation position of the lower pressure tap;
A liquid level calculation device comprising: On the computer,
Regarding the upper and lower pressure taps installed in the pressure vessel of a nuclear power plant,
The pressure at the upper pressure tap installation position is
A process for calculating a pressure of a liquid at a predetermined measurement location in a container containing the liquid, comprising:
A step of obtaining an analytical value of an average pressure for each of a plurality of compartments when the container is divided into the plurality of compartments;
selecting the analysis value of a target section, the section including the measurement location, from among the plurality of sections;
calculating a pressure at the measurement location by correcting an average pressure in the target area based on the height of the measurement location relative to the height of the entire target area;
by implementing the vessel as the pressure vessel using a pressure calculation process having
Calculating the pressure at the location of the lower pressure tap using the pressure calculation process by treating the vessel as the pressure vessel;
A process of calculating a liquid level of the pressure vessel from a pressure difference between a pressure at an installation position of the upper pressure tap and a pressure at an installation position of the lower pressure tap;
A program that executes the following.

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