JPH02290596A - Flow rate measuring instrument and operating device for nuclear reactor utilizing this instrument - Google Patents

Abstract

PURPOSE:To exactly measure flow rates by providing a computing means in which the piping network model equiv. to prescribed flow passages is programmed and analytically computing the flow rates while corresponding the respective constants of the predetermined piping network model to a rotating speed signal. CONSTITUTION:The rotating speed signals from speedometers 22 which measure the rotating speeds of motors 11 for driving circulating pumps 10 are respectively inputted to the piping network model computing element 30. The computing element 30 calculates the total sum of the flow rates discharged from the entire part of the circulating pumps when one or plural units of the pumps among the plural circulating pumps stop or slow down in rotating speed. The piping network model equiv. to the flow passages of the cooling water in a pressure vessel 1 is previously programmed in the computing element 30. The flow rates in the respective parts on the piping network model is analytically computed in accordance with the rotating speed signals of the pump inputted to the computing element 30 from the speedometers 22 and the flow rate signals which are the results thereof are inputted to a calibration switch 28. The switch 28 selectively switches the flow rate signals outputted from the computing element 27 or the computing element 30. The calibration of the signal from the computing element 27 and the back up of the system of this computing element 27 are executed.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a flow rate measuring device and method for measuring the flow rate in any part of a flow path when a fluid in a container is moved by a fluid moving means. Furthermore, in a nuclear reactor where the coolant inside the pressure vessel is circulated by multiple pumps, the reactor output is controlled by accurately measuring the flow rate of the coolant circulated by these pumps. Regarding the operating device. (Prior art) In a boiling water reactor, cooling water inside a pressure vessel is circulated through the reactor core using multiple circulation pumps. In such boiling water reactors, it is necessary to accurately measure the flow rate and flow rate distribution of cooling water circulating through the reactor core, and to constantly monitor the reactor status. The general structure of a conventional boiling water reactor and the method for measuring the cooling water flow rate will be explained with reference to Figure 6. This nuclear reactor is equipped with a pressure vessel 1, and a reactor core 2 is accommodated within this pressure vessel 1. This reactor core 2 is housed in a shroud (partition plate) 6, and a steam-water separator 3 is provided above the shroud 6 to separate water from the steam generated in the core 2 and to produce dry steam. It is supplied to a turbine, etc. (not shown). The cooling water separated from the steam descends through a passage formed between the outer peripheral surface of the shroud 6 and the inner peripheral surface of the pressure vessel 1, and is sent to the lower part of the core 2 by a plurality of circulation pumps 10. , flows into the reactor core 2 from below, boils within the reactor core, and flows out from the upper part of the reactor core. The coolant then circulates through the path described above. The above-mentioned circulation pumps 10 are each driven via a shaft 9 by a motor 11 arranged outside the pressure vessel. In such a reactor, it is necessary to accurately measure the flow rate of cooling water flowing into the reactor core and monitor the reactor status. Conventional measurement means for measuring the flow rate of cooling water are configured as follows. Openings 25A and 25B of conduits of a plurality of sets of core inlet differential pressure gauges 25 are opened in the core inlet 14 of the core 2 described above. Note that the openings of these conduits are arranged at the core support plate of this core 2 or at the entrance nozzle of the fuel assembly. Pressure signals corresponding to the pressures introduced through these openings are sent to the differential pressure/flow rate converter 26,
Coolant flow rate is measured.

A plurality of pump differential pressure gauges 23 are provided separately for calibrating and backing up the core inlet differential pressure gauge 25 described above. The openings 23A and 23B of the conduits of these pump differential pressure gauges 23 are arranged on the suction side and the discharge side of each circulation pump 10. The differential pressure signal output from the pump differential pressure gauge 23 is input to the pump computing unit 24. Further, the rotational speeds of the motors 11 that drive these circulation pumps IO are each measured by speedometers 22, and the speed signals output from these speedometers 22 are input to the pump section calculator 24 mentioned above. For each of the above-mentioned circulation pumps 10, the relationship between these parameters and the discharge flow rate of the pump is determined in advance on a test stand (by a separate test) using the differential pressure between the suction side and the discharge side and the rotation speed of the pump as parameters. , these relationships are programmed in advance into the pump section calculator 24. therefore,
This pump section calculator 24 measures the flow rate of each circulation pump IO. The flow rate signals of each circulation pump outputted from the pump section calculator 24 are input to the calculator 27, and the sum of the flow rates of all these circulation pumps is determined. The flow rate signals outputted from this calculator 27 and the differential pressure/flow rate calculator 26, respectively, are input to the reactor operation monitoring device 29 via a calibration switch 28. By switching and operating this calibration switch 28, the above-mentioned core inlet differential pressure gauge 25 is calibrated, and backup is performed in case this system malfunctions. By the way, in the system of the pump section differential pressure gauge 23, when some of the plurality of circulation pumps 10 are stopped or partially operated, the measurement accuracy decreases.
The reason for this will be explained with reference to FIGS. 7(a) and 7(b).

FIGS. 7(a) and 7(b) are schematic cross-sectional views of the pressure vessel 1 at the level where these circulation pumps 10 are arranged. Reference numeral 12 in these figures indicates a cylindrical shroud support leg, and this shroud support leg 12 has a position corresponding to the front of each circulation pump 10 and a position corresponding to the middle of two adjacent circulation pumps 10. A leg opening 13 is formed in each. FIG. 7(a) shows a state in which all circulation pumps 10 are operated at approximately the same rotational speed, and the flow of coolant is indicated by arrows. In this case, a portion of the coolant discharged from each circulation pump 10 flows directly into the lower plenum of the core from the leg gap 13 corresponding to the position of each circulation pump,
In addition, the remaining part of the coolant discharged from each circulation pump IO flows in the horizontal circumferential direction, and the remaining part of the coolant discharged from each circulation pump IO flows horizontally and
These coolant flows from the circulation pumps 10 join midway between the circulation pumps 10 and enter the lower plenum of the core through leg openings 13 located between the circulation pumps 1G. Furthermore, in Fig. 7(b), black arrows indicate the flow of coolant when some circulation pumps IOB are stopped and other circulation pumps IOA are operated at the same rotational speed. In this case, the coolant that has flowed in the circumferential direction from the circulation pumps IOA on both sides of the stopped circulation pump IOB flows to the discharge side of the stopped circulation pump IOA, and a portion of the coolant that has flowed to the discharge side flows into the lower plenum of the core through the leg opening 13 corresponding to this circulation pump IOA,
The remaining part flows back through the stopped circulation pump 10B. Therefore, in such a case, the flow rate of coolant flowing into the reactor core 2 cannot be calculated accurately even if the flow rates of coolant discharged from each shield ring pump IOA in operation are totaled. The case explained with reference to Fig. 7(b) above is a simple case for ease of understanding, but in an actual plant, multiple circulation pumps are stopped and then operated again. Circulation pumps may be operating at different rotational speeds, so even if one or more pumps stop for some reason, it is possible to slightly increase the rotational speed of the remaining pumps. It is required to ensure the flow of coolant and continue plant operation. Accurately measuring the coolant flow rate in such complicated cases was difficult. Furthermore, the above-mentioned problems occur not only in the case of measuring the flow rate of coolant circulating in the pressure vessel of a nuclear reactor, but also in other equipment, chemical plants, etc. For example, in heat exchangers, boilers, stirring devices in chemical plants, dialysis devices, gas reaction devices, solid/fluid separation devices, etc., complex fluid circulation and circulation channels are formed in containers. It has a structure in which fluid flows through the channel. Even with these devices, it is difficult to accurately measure the state of fluid flow inside the vessel when operated under conditions that deviate from normal operating conditions. There is a need to accurately measure the flow rate of fluids that flow in complex ways. (Problem to be solved by the invention) In this kind of plant or equipment,
Complex fluid circulation and circulation channels are formed within the container, and the structure is such that fluid flows through these channels. Even with these devices, it is difficult to accurately measure the state of fluid flow inside the vessel when operated under conditions that deviate from normal operating conditions. There is a need to accurately measure the flow rate of fluids that flow in complex ways. It is also required to keep the operating state stable at all times.

The present invention has been made to satisfy the above-mentioned needs, and its purpose is to provide a system in which fluid in a container is circulated through a predetermined flow path formed in the container by a fluid circulation means. The purpose of the present invention is to provide a flow rate measuring device that can accurately measure the flow rate of this fluid even when the state of the fluid has changed from normal. This product provides a nuclear reactor operating system that constantly and stably controls the operation of a nuclear reactor. [Structure of the Invention] (Means for Solving the ML Problem) The flow rate measuring device of the present invention detects the rotational speed of a motor that drives a fluid moving means using a rotational speed detection means, and generates a signal corresponding to this rotational speed. pipe network
) is input to the calculation means, and this pipe network calculation means is programmed with a pipe network model equivalent in terms of fluid circuit to the fluid flow path formed in the container. The constant corresponding to the fluid circulation means in the model is set to a value corresponding to the rotation speed of the motor that drives this fluid circulation means, and the flow rate of any part on this pipe network model is calculated analytically. From the calculation results, the flow rate of a portion within the container corresponding to an arbitrary portion on this pipe network model is measured.

Further, the nuclear reactor operating device of the present invention includes a control means for controlling the output of the reactor by controlling at least one of the flow rate of the core coolant circulated through a predetermined flow path by a plurality of pumps or the control rods. In the operating device for a nuclear reactor, a rotation speed detection means for detecting the rotation speed of each of the plurality of pumps, a rotation speed signal from the rotation speed detection means is input, and the flow rate is calculated based on the rotation speed signal. calculation means for calculating a predetermined rotation speed and correlation of the pump, the calculation means being programmed in advance with a pipe network model equivalent to the predetermined flow path; The constants of each part of the pipe network model having the above are set in correspondence with the rotation speed signal, the flow rate of any part of the pipe network model is analytically calculated, and the flow rate signal is output from the calculation means. This is a nuclear reactor operating device characterized in that the output of the nuclear reactor is controlled by inputting the following information into the control means. (Function) According to the flow rate measuring device of the present invention, the flow path of the fluid in the container is replaced with a pipe network model, and the flow rate is calculated on this pipe network model. The flow rate in a section can be easily and accurately calculated. Therefore, even if the flow path through which the fluid flows in this container is complex; or even if multiple fluid circulation means are provided, the flow rate in any part of the flow path in this container can be easily and easily controlled. It can be calculated accurately. Further, the flow rate measuring device of the present invention is particularly effective as a device for measuring the flow rate of cooling water circulating in the pressure vessel of a boiling water nuclear reactor. Inside this pressure vessel, members such as a core, a shroud, and shroud support legs are housed, and cooling water is circulated by a circulation pump through a flow path formed between these members. This flow path is not in the form of a pipe completely surrounded by walls and has a complicated shape, and cooling water is circulated through such a flow path by a plurality of circulation pumps. Furthermore, when these pumps are stopped, backflow occurs, making the flow of cooling water within the pressure vessel extremely complicated. Therefore, it is difficult to actually measure the flow rate at any part within this pressure vessel. In measuring the flow rate of the coolant in the pressure vessel of such a nuclear reactor, as in the present invention, this flow path is replaced with a pipe network model, and the rotation speed of the circulation pump is set as a variable corresponding to this pipe network model. By replacing it with , and calculating the flow rate on this pipe network model, the flow rate of the coolant in this pressure vessel can be easily and accurately measured. In particular, when applied to measuring the circulating flow rate of core coolant inside a reactor pressure vessel, the pipe network model is constructed as shown in Figure 3. Here, α and ~α are pipe resistances representing pump discharge section loss, pump-to-pump loss, leg section loss, and furnace pressure loss, respectively, and x, y, and z represent flow rates at each section, pi represents the Q-H characteristics (including backflow characteristics) of each pump. Using this analytical model, we can numerically solve the multidimensional simultaneous nonlinear equations formulated by the flow rate continuity conditions at each node and the pressure closure conditions at each closed pipe, and then analyze the flow rates x, y, and z at each part. It can be found exactly.

That is, if each constant (equivalent pipe resistance and pump backflow characteristic) of the pipe network model is determined in advance using the circulation pump differential pressure gauge 23 under various operating conditions of each circulation pump, these values can be used to calculate the The accuracy of measuring the coolant circulation flow rate in the reactor core can be dramatically improved by determining the flow rate at each part analytically determined by the method. Furthermore, by optimizing (recalibrating) the values of each constant of the pipeline network model at any time or periodically using the above procedure, it is possible to deal with temporal changes in pressure loss in the reactor at the end of the fuel cycle, etc. It can be used flexibly and maintain highly accurate flow measurement.

Furthermore, the output of the reactor can be easily controlled by feeding back the flow rate measurement results to the control means to control at least one of the flow rate of the cooling water and the position of the control rods, allowing for highly accurate operation control. (Example) Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 5. FIG. 1 shows a schematic configuration of a boiling water reactor equipped with a flow rate measuring device according to a first embodiment of the first invention. This nuclear reactor is equipped with a pressure vessel 1, and a reactor core 2 is housed within this pressure vessel 1. This core 2 is housed in a shroud 6, and a steam separator 3 is provided on the top of this shroud 6 to separate water from the steam generated in the core 2 and supply dry steam to a turbine, etc. (not shown). ．． The cooling water separated from the steam descends through a passage formed between the outer peripheral surface of the shroud 6 and the inner peripheral surface of the pressure vessel 1, and is sent to the lower part of the core 2 by a plurality of circulation pumps 1o. It flows into the reactor core 2 from below, boils within the reactor core, and flows out from the upper part of the reactor core. The cooling water then circulates through the path described above. The circulation pumps 1o are each driven via a shaft 9 by a motor l1 arranged outside this pressure vessel. ,, -0 [In order to accurately measure the flow rate and flow rate distribution of the cooling water flowing into the reactor core, and to monitor the status of the reactor, the flow rate of such cooling water is certified. Measurement means are provided. Core inlet section 14 of the above-mentioned reactor core 2
Openings 25A and 25B of the conduits of a plurality of sets of core inlet differential pressure gauges 25 are opened in the. Note that the openings of these conduits are arranged at the core support plate of this core 2 or at the entrance nozzle of the fuel assembly. Pressure signals corresponding to the pressure introduced from these openings are sent to the differential pressure/flow rate converter 26, and the flow rate of the cooling water is measured. Although FIG. 1 shows only one system of the core inlet differential pressure gauge 25, in an actual nuclear reactor, multiple systems of such core inlet differential pressure gauges are provided. A plurality of pump differential pressure gauges 23 are provided separately for calibrating and backing up the core inlet differential pressure gauge 25 described above. These pump section differential pressure gauges 23 are provided for each circulation pump. The present invention is applied to the system of these pump differential pressure gauges 23. These pump section differential pressure gauges 23 conduit openings 23A, 2
3B are arranged on the suction side and the discharge side of each circulation pump 10. The differential pressure signal output from the pump differential pressure gauge 23 is input to the pump computing unit 24. Further, the rotational speeds of the motors 11 that drive these circulation pumps 10 are each measured by speedometers 22, and speed signals outputted from these speedometers 22 are inputted to the pump section calculator 24 described above. For each circulation pump 10 described above, the differential pressure between the suction side and the discharge side and the pump rotation speed are used as parameters in advance on a test stand, and the relationship between these parameters and the pump discharge flow rate is determined. It is programmed in advance in the pump section calculator 24. Therefore, the flow rate of each circulation pump 10 is measured by this pump section calculator 24. The flow rate signals of each circulation pump output from the pump calculator 24 are input to the calculator 27, and the sum of the flow rates of all these circulation pumps is determined. The flow rate signals outputted from this calculator 27 and the differential pressure/flow rate calculator 26, respectively, are input to the reactor operation monitoring device 29 via a calibration switch 28. By switching and operating this calibration switch 28, the above-mentioned core inlet differential pressure gauge 25 is calibrated and backup is performed in case this system malfunctions. Further, rotational speed signals from the speedometers 22 that measure the rotational speeds of the motors 11 that drive these circulation pumps 1o are respectively input to the pipe network model calculator 30. This pipe network model calculator 30 calculates information from all of these circulation pumps when one or more of the plurality of circulation pumps 1O stops or the rotational speed decreases. This calculates the total amount of discharged flow rate. The pipe network calculator 30 has a pipe network (pipe n
etwork) model is pre-programmed. Below, we will explain the relationship between this flow path and the corresponding pipe network model. FIG. 2(a) shows a side view of a portion where the circulation pump 10 is arranged, and FIG. 2(b) shows a schematic plan view of this portion. FIG. 2(a) is a side view of the lower part of the shroud 6 and the shroud support leg 12 seen from inside, and shows the relationship between the outer peripheral surface of the lower part of the shroud 6 and the inner peripheral surface of the pressure vessel 1. A ring-shaped pump deck 15 is arranged at the bottom of the passage so as to close the passage. A plurality of circulation pumps 10 are arranged at equal intervals in the circumferential direction, penetrating this pump deck l5. In addition, nozzles 9 are provided at the lower ends of these circulation pumps 10.
The cooling water sucked in from the suction ports at the upper ends of these circulation pumps 1o is discharged from these nozzles 9a. Further, the lower end portion of the shroud 6 is supported by a cylindrical shroud support leg 12. Leg openings 13a are formed in the shroud support legs 12 at positions corresponding to the front surfaces of the circulation pumps 10, and the adjacent circulation pumps 10
A leg opening 13b is also formed at an intermediate position between. (Please note that the shroud support leg 12 is
0, that is, in front of the pump 10 and at an intermediate position between the adjacent pumps 10.

(See Japanese Patent Application No. 63-144781.) The state of the flow of cooling water discharged from each of the circulation pumps 10 described above is shown by arrows in FIGS. 2(a) and 2(b).

f discharged from the nozzles 9a of these circulation pumps 10
E is divided into a circumferential flow f2 and a radial flow f3, where f3 directly passes through the leg opening 13a and flows into the lower plenum of the core, while f2 is connected to the flow f2 from the adjacent circulation pump at point g. They merge to form a radial flow f3 that passes through the leg opening 13b and flows into the lower plenum of the core.

FIG. 2(c) shows a model in which such a cooling water flow path is replaced with a pipe network model. In this pipe network model of Fig. 2(c), the pipe network model of Fig. 2(a). Pipe lines and branch points corresponding to the flow path in (b) are indicated by the same reference numerals, and the flow resistance of each conduit (flow channel) is indicated by α■, α2, α3, α, respectively.

As described above, the pipeline network model formed in this way is generated in advance by the pipeline network model calculator 30? programmed. Then, based on the pump rotational speed signal input from the speed meter 22 to the pipe network calculator 30, the flow rate of each part is analytically calculated on this pipe network model,
The resulting flow rate signal is input to the calibration switch 28 described above. This calibration switching device 28 selectively switches the flow rate signal output from the above-mentioned computing device 27 or the pipeline network computing device 30 as needed and sends it to the operation monitoring device 29. The signal from the arithmetic unit 27 is calibrated using the signal from the arithmetic unit 27, and the system of this arithmetic unit 27 is backed up.

Next, details of such analytical calculation will be explained with reference to FIG.

In the figure, Pi-■r Pit Pi+ correspond to the circulation pump 10, respectively, and represent the Q-H characteristics (including backflow characteristics) of each pump 1o. Here, Q: pump flow rate,
H: Pressure loss (loss head).

Mata, α■, α2, α,, α. indicates the pipe resistance, α1 is the discharge loss of each pump (loss caused by the pump discharging coolant downward and colliding with the bottom of the pressure vessel 1, etc.), and α2 is the loss between each pump. , α■ is the shroud support leg 12 part loss, α4 is the pressure loss in the reactor (there is a possibility that it will change over time due to various losses during the time when the coolant passes through the reactor core 2 and returns to the pump 10.) x, y, and z represent the flow rate of each part.

Using the pipeline network model shown in Fig. 2(c) and Fig. 3, the simultaneous conditions for each element are formulated by the flow rate continuity condition at each node (each branch point) and the pressure closure condition at each closed pipeline. By solving the nonlinear equation numerically, the flow rates x, y, and z of each part can be analytically determined. That is, (1) Continuity condition for flow rate at each node The flow rate flowing into each node (each branch point) is equal to the flow rate flowing out from the same node.

Σ qi=Q...■ However, 91 is the inflow or outflow amount from each pipe line 1, 2...m connected to each node.

■ Pressure closure conditions in closed pipes The algebraic sum of the pressure loss (loss head) around each element closed pipe is zero. The pressure loss in each pipe is expressed as hi, for example, when the flow direction is clockwise, hi>O, and when the flow direction is counterclockwise, hi
If <O is chosen, Σ hi=o... ■ However, m is the number of pipes that constitute one element closed pipe line.

The flow rate of each part is determined by creating a nonlinear simultaneous equation at each node based on the above equations (■) and (■) and solving it numerically.

That is, various operating conditions 1r of each circulation pump! In A (including the backflow state during partial pump operation), each constant (equivalent pipe resistance and pump backflow characteristic) of the pipe network model is determined in advance using the circulation pump section differential pressure system 23, and the pipe network calculation unit 30, and by correcting the core flow rate using the core inlet/differential pressure system 25 based on the flow rate of each part analytically determined using these values, the rotation speed of the circulation pump 10 can be made uniform. , the measurement accuracy of the coolant circulation flow rate in the reactor core is dramatically improved regardless of non-uniformity. Further, even if a problem occurs in the flow rate measurement by the core inlet differential pressure system 25 for some reason, the necessary measurement accuracy can be maintained by measuring the flow rate only by the pipe network calculator 30.

Furthermore, by optimizing (recalibrating) the values of each constant of the pipeline network model at any time or periodically using the above procedure, it is possible to deal with temporal changes in pressure loss in the reactor at the end of the fuel cycle, etc. It is possible to respond flexibly to any situation and maintain highly accurate flow measurement.

Further, as described above, the necessary measurement accuracy can be obtained even by measuring the flow rate using only the pipe network calculator 30, so that the configuration can be simplified and costs can be reduced. In other words, the fourth
As shown in the figure, the speed meter 22 attached to each drive motor 11 of a plurality of circulating pumps 10 is sent to the pipeline network calculator 30, and The above-mentioned flow rates at each part may be determined from the Q-H characteristics unique to each pump (with slight variations), and each constant of the pipe network model determined and stored in advance. The flow rate is then displayed on the operation monitoring device 29. Of course, flow rate measurement using the pipe network calculator 30 and flow rate measurement using either the differential pressure at the core inlet or the differential pressure near the inlet and outlet of the circulation pump 10 may be used in combination.

In the above-mentioned embodiment, the measuring device of the present invention is applied to a coolant flow rate measuring device for a boiling water reactor, so that the operation control of this nuclear reactor can be performed easily and with high precision. Reliability of furnace operation control is high. Furthermore, Fig. 5 shows an embodiment of the second invention. This device includes a controller 31, and the above-mentioned pipeline network calculator 30 is built into the controller 31. The rotation speed of the motor l1 of each circulation pump is detected by the speed meter 22, and these speed signals are input to the controller 31. Although only two systems of speedometers 22 are shown in FIG. 5, these speedometers 22 are provided for each motor of each circulation pump. The controller 3l calculates the flow rate of the cooling water in the same way as in the embodiment described above, and based on the result, sends a control signal to the motor 11 of each circulation pump to control the operation of these circulation pumps 10. , the output of the reactor is controlled by controlling the circulating flow rate of cooling water. Note that the controller 3l may output control rod position adjustment signals and other signals to control the core output and the operation of the entire reactor.

In the explanation of the above embodiment, the present invention was explained using as an example a device applied to measuring the circulating flow rate of cooling water in the pressure vessel of a boiling water reactor, but the present invention is not limited to this embodiment. It is clear that it will not.

For example, in heat exchangers, boilers, stirring devices in chemical plants, dialysis devices, gas reaction devices, solid/fluid separation devices, etc., complex fluid distribution and circulation paths are formed in containers, and such paths are It has a structure that allows fluid to flow through it. Even with these devices, it is difficult to accurately measure the state of fluid flow inside the vessel when operated under conditions that deviate from normal operating conditions. There is a need to accurately measure the flow rate of fluids that flow in complex ways. Therefore, if the flow measuring device of the present invention is applied to such various devices, the flow rate of the fluid in any part of the container can be easily and accurately measured, and the operation management and control of these devices can be improved. This greatly improves the reliability and accuracy of the system.

Furthermore, not only the flow rate of liquid but also the fan device (cooling device)
The present invention has a wide range of applications, including the semiconductor field, OA, and AV equipment fields.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to measure the circulating flow rate with high precision, and particularly when applied to the flow rate measurement of the core coolant of a nuclear reactor, it is possible to measure the circulating flow rate regardless of whether the rotation speed of the circulating pump is balanced or unbalanced. In addition, the core flow rate can be measured with high accuracy even during so-called partial pump operation when one or more circulation pumps are stopped, improving the reliability of the measurement system and improving the reliability of the entire reactor. It also contributes to improvement.

In addition, it can flexibly deal with temporal changes in flow resistance in the reactor, and can be used over almost the entire operating life of the plant.
Highly accurate core flow measurement can be maintained.

This will improve the accuracy of nuclear reactor operation control.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing a partial block diagram of a core coolant circulating amount measuring device in a nuclear reactor according to the present invention, and Fig. 2 shows a pipe network model that equivalently replaces the coolant flow path in the reactor. FIG. 3 is a detailed diagram of a pipeline network model; FIGS. 4 and 5 are cross-sectional views showing a partial block diagram of a circulating flow rate measuring device to show other embodiments of the present invention; FIG. Figure 6 is a cross-sectional view showing a partial block diagram of a conventional core coolant circulation flow measurement device in a nuclear reactor, and Figure 7 is a pump discharge flow when all pumps are operating and when partial pumps are operating (one pump is stopped). FIG. 2 is an explanatory diagram showing a pattern in the flow direction. 1...Reactor pressure vessel (vessel), 2. ...Reactor core, 3... Steam separator, 6... Partition plate (shroud), 9... Pump shaft, 10... Pump (fluid moving means), 11... Pump drive motor, 12... Shroud support leg, 13... Leg Opening, 22... Pump speed meter (rotation speed detection means), 23... Pump section differential pressure gauge, 24... Pump section computing unit, 25... Core inlet differential pressure gauge, 26... Differential pressure flow rate converter, 27... Computing unit,
28... Calibration switching device, 29... Operation monitoring device, 30... Pipe network calculation unit (pipe network calculation means). Agent Patent Attorney Noriyuki Chika Yudo Masaru Matsuyama Figure 1, Figure 5, Figure 5

Claims (6)

[Claims] (1) In a flow rate measurement device that allows fluid in a container to flow through a predetermined flow path by a fluid moving means having a motor and measures the flow rate in any part of this flow path, rotation speed detection that detects the rotation speed of the motor. and calculation means for receiving a rotational speed signal from the rotational speed detection means and calculating the flow rate based on the rotational speed signal, wherein the calculation means has a flow path equivalent to the predetermined flow path in advance. A conduit network model is programmed, and constants of each part of the conduit network model having a correlation with a predetermined arbitrary rotation speed of the motor are set in correspondence with the rotation speed signal, A flow rate measuring device, characterized in that it analytically calculates the flow rate of any part of the pipe network model. (2) A plurality of pumps are disposed in the circumferential direction on the outside of the shroud, which is fixed via a shroud support leg in which a plurality of leg openings are formed at the bottom of the reactor pressure vessel, and a plurality of pumps are disposed in the circumferential direction of the shroud, and A flow rate measuring device in which coolant flows through a predetermined flow path and measures the flow rate in any part of the flow path, comprising: rotation speed detection means for detecting the rotation speed of each of the plurality of pumps; and from the rotation speed detection means. a calculation means for receiving a rotation speed signal and calculating the flow rate based on the rotation speed signal, the calculation means being programmed in advance with a pipe network model equivalent to the predetermined flow path. constants of each part of the pipe network model that have a correlation with an arbitrary rotation speed of the pump that has been determined in advance are set in correspondence with the rotation speed signal, and A flow rate measuring device characterized in that it analytically calculates the flow rate of. (3) Differential pressure measuring means for detecting the differential pressure between the inlet and outlet portions of the core coolant of at least one of the pumps, and the differential pressure and the flow rate of the core coolant that are determined in advance for each arbitrary number of revolutions of the pump. core coolant flow rate measuring means for measuring the flow rate from the pump rotational speed detected by the rotational speed detection means and the differential pressure detected by the differential pressure measuring means, using the correlation between the 3. The flow rate measuring device according to claim 2, wherein said calculation means is used for calibrating a core coolant flow rate measuring means. (4) The pump is disposed in a passage formed between the outer circumferential surface of the shroud and shroud support legs and the inner circumferential surface of the pressure vessel, and the pipe network model includes a nozzle portion of the pump, Each flow path from the nozzle part to the leg opening, from the nozzle part to the midpoint between the adjacent pump in the passage, and from this midpoint to the leg opening is replaced with a closed pipe. 3. The flow rate measuring device according to claim 2, characterized in that: (5) The constants of each part of the pipeline network model are calculated using n pumps (
n = 1, 2, 3...), each Q-H characteristic is Pn (where Q: pump flow rate, H: pressure loss), the discharge part loss of the nozzle part of the pump is α_1, and the loss between the pumps is α＿
2. The shroud support leg loss is α_3, the pressure loss in the furnace is α_4, and these α_1, α_2, α
3. The flow rate measuring device according to claim 2, wherein _3 and α_4 are respectively applied as pipe resistances of corresponding closed pipes in the pipe network model. (6) A nuclear reactor operating device comprising a control means for controlling the output of the reactor by controlling at least one of the flow rate of the core coolant circulated through a predetermined flow path by a plurality of pumps or a control rod, A rotation speed detection means for detecting the rotation speed of each of a plurality of pumps; and a calculation means for receiving a rotation speed signal from the rotation speed detection means and calculating the flow rate based on the rotation speed signal, A pipe network model equivalent to the predetermined flow path is programmed in advance in the calculating means, and constants of each part of the pipe network model have a correlation with an arbitrary rotation speed of the pump determined in advance. is set in correspondence with the rotational speed signal, the flow rate of any part of the pipe network model is calculated analytically, the flow rate signal outputted from the calculation means is inputted to the control means, and the atomic A nuclear reactor operating device characterized by controlling the output of the reactor.