Method and system for monitoring nuclear power plants by detecting and characterizing imbalances

Abstract

A method for monitoring a nuclear power plant is proposed, which is implemented by a monitoring system that makes it possible to carry out the monitoring in a reliable manner. [Solution] The monitoring method includes determining, for each steam generator of a plurality of steam generators and for at least one parameter of a set of representative parameters of the operation of the steam generators, a deviation between a measured value of the parameter of the steam generator and an average value of the parameter of all the steam generators to detect an imbalance of the parameter in the steam generator, and characterizing the imbalance as a function of one or more other parameters of the set of representative parameters to generate a physical problem signal or a measured deviation signal.

Description

Technical Field

[0001] The present invention relates to the field of monitoring nuclear power plants.

Background Art

[0002] A nuclear power plant has a separated primary water circuit (or "primary circuit") and secondary water circuit (or "secondary circuit"), a nuclear reactor that heats the water circulating in the primary circuit, a plurality of steam generators arranged to transfer heat from the primary circuit to the secondary circuit and generate steam in the secondary circuit, and a steam turbine incorporated in the secondary circuit that generates mechanical energy from the steam generated by the steam generators. This mechanical energy can be converted into electrical energy using a generator connected to the steam turbine.

[0003] Nuclear power plants are generally equipped with sensors that measure operating parameters used to monitor and control the nuclear power plant.

[0004] These operating parameters are used, for example, by a monitoring system configured to automatically monitor and / or control the nuclear power plant.

Summary of the Invention

Problems to be Solved by the Invention

[0005] One object of the present invention is to propose a method for monitoring a nuclear power plant implemented by a monitoring system that enables monitoring to be performed in a highly reliable manner.

Means for Solving the Problems

[0006] To achieve this object, the present invention is a method for monitoring a nuclear power plant executed by a monitoring system, comprising A nuclear power plant has a primary circuit, a secondary circuit, a reactor located in the primary circuit to heat the water circulating within the primary circuit, and N steam generators (where N is an integer greater than or equal to 2) located in the secondary circuit to transfer heat from the primary circuit to the secondary circuit by generating steam within the secondary circuit. The monitoring system is equipped with sensors for measuring parameters of a set of representative parameters for the operation of each steam generator. The monitoring method involves monitoring at least one parameter of a set of representative parameters, and for each steam generator. - Based on the measurements provided by the sensor, determine the deviation between the measured value of this steam generator parameter and the average value of this parameter across all steam generators, and detect imbalances in this parameter in the steam generator, and, - Characterizing imbalances that affect the parameters of this steam generator according to one or more other parameters in a set of representative parameters, and generating a physical problem signal indicating the presence of a physical problem in the steam generator affected by the imbalance, or a measurement deviation signal indicating the measurement deviation of the parameters considered in the steam generator affected by the imbalance. We propose a monitoring method that includes this.

[0007] By comparing the measured values ​​of a steam generator's parameters with the average values ​​of these parameters across all steam generators, it is possible to identify imbalances in these parameters for that particular steam generator.

[0008] Such imbalances may be caused by physical problems with the steam generator, i.e., actual problems in the steam generator that are affected by the imbalance, or by deviations in the measurement of the aforementioned parameters of the steam generator, i.e., measurement errors of the sensors that determine the values ​​of these parameters.

[0009] Each other parameter considered for characterizing the imbalance detected by the parameter being considered is preferably another parameter that is linked to the parameter being considered and, in principle, should also be affected by the imbalance.

[0010] By characterizing the imbalance in the steam generator parameters against one or more other parameters, the monitoring system can automatically generate a signal indicating that the detected imbalance is due to a physical problem with the steam generator or a deviation in the measured value of that parameter of the steam generator.

[0011] Therefore, by characterizing the imbalance, the operator or monitoring system controlling the nuclear power plant can take appropriate measures after detecting the imbalance, depending on whether the imbalance is a physical problem or a measurement deviation.

[0012] In the characterization of physical problems, it is possible to control the nuclear power plant to correct the physical problems or to switch the nuclear power plant into an operating mode to resolve the physical problems. When characterizing measurement deviations, it is possible to correct the measurements that have been performed or to perform maintenance (repair or replacement) on one or more defective pieces of equipment while the power is on or off.

[0013] According to a particular embodiment, the monitoring method comprises one or more of the following selectable characteristics, which are obtained individually or in all technically possible combinations: - For at least one parameter of the set of representative parameters, the characterization of parameter imbalance is performed for at least one or each of the other parameters, in accordance with the deviation between the measured value of this other parameter for the steam generator under consideration and the reference value of this other parameter for all steam generators, the reference value being selected from the mean value of this other parameter and the set value of this other parameter. - The monitoring method includes comparing at least one or each deviation between a parameter's measured value and a reference value to one or more comparison thresholds in order to detect an imbalance in this parameter or in other parameters, wherein the reference value is selected from the mean and set values ​​of this parameter, and the reference value is selected from the mean and set values ​​of the parameters concerned. - For at least one parameter of the set of representative parameters, the characterization of the imbalance in the parameters of the steam generator under consideration includes the following: - If the calculated deviation for this parameter is less than the lower threshold associated with this parameter or greater than the upper threshold associated with this parameter, and if the deviation between the measured value and preferably the average value calculated for this other parameter and the reference value of this other parameter from a set of representative parameters selected from the set values ​​of this other parameter filtered optionally using a phase-leading filter is less than the lower threshold associated with this other parameter or greater than the upper threshold associated with this other parameter, then a physical problem signal is emitted, and / or -Emitting a measurement deviation signal when the deviation calculated for this parameter is less than the lower threshold associated with this parameter or greater than the upper threshold associated with this parameter, and when the deviation between the measured value and preferably the mean calculated for the other parameter and the reference value of the other parameter in a set of representative parameters selected from the set values ​​of the other parameter filtered using a phase-leading filter is not less than the lower threshold associated with this other parameter and is not greater than the upper threshold associated with this other parameter. - For each steam generator and at least one parameter of the set of representative parameters, the characterization of the imbalance of this parameter in the steam generator includes the following: - If the deviation between the measured value and the calculated mean value for this parameter is less than a negative lower threshold, and the deviation between the measured value and preferably the calculated mean value for this other parameter and the reference value of the other parameter in a set of representative parameters selected from the set values ​​of this other parameter filtered using a phase-leading filter is less than a negative lower threshold, then the first physical problem signal is transmitted. - If the deviation between the measured value and the calculated mean for this parameter is less than a negative lower threshold, and the deviation between the measured value and the reference value of any other parameter filtered using a phase-leading filter is not less than a negative lower threshold, then a first measurement deviation signal is transmitted. - If the deviation between the measured value and the calculated mean of this parameter is greater than a positive upper threshold, and the deviation between the measured value and the reference value of other parameters filtered using an optional phase-leading filter is greater than a positive upper threshold, then a second physical problem signal is emitted, and / or - If the deviation between the measured value and the calculated mean for this parameter is greater than a positive upper threshold, and the deviation between the measured value and the reference value of any other parameter filtered using a phase-lead filter is not greater than a positive upper threshold, then a second measurement deviation signal is generated. - For each steam generator and at least one parameter of a set of representative parameters, an alarm signal is issued when the deviation between the measured value and the reference value is less than the lower alarm threshold, and / or when the deviation between the measured value and the reference value is greater than the upper alarm threshold, the reference value being selected from the average value of this parameter and the set value of this parameter. - The deviation between the measured value and the reference value is filtered using a phase-leading filter before being compared to the lower alarm threshold and / or the upper alarm threshold. -Characterizing the imbalance of at least one parameter or each parameter of a set of representative parameters includes considering the alarm signals emitted for other parameters of the set of representative parameters. - For each steam generator and at least one parameter of the set of representative parameters, a deviation signal is emitted when the deviation between the measured value and the reference value of this parameter is less than the lower deviation threshold, and / or when the deviation between the measured value and the reference value of this parameter is greater than the upper deviation threshold, the reference value is selected from the mean value and the set value of this parameter. - The characterization of imbalance in at least one parameter of the steam generator is performed in response to the deviation signal emitted for this parameter and the alarm or deviation signal emitted from at least one other parameter that has been characterized. - For each steam generator, the set of representative parameters includes one or more of the following parameters: steam flow rate, steam pressure, feedwater flow rate, feedwater temperature, purge flow rate, liquid level, and primary output. - The characterization of steam pressure imbalance in a steam generator is performed, for example, depending on the steam flow rate and primary output, and in particular, depending on the deviation between the measured steam flow rate of this steam generator and the average steam flow rate of the steam generator, and the deviation between the measured primary output of this steam generator and the average primary output of all steam generators. - The characterization of the steam flow imbalance of a steam generator is performed, for example, according to the steam pressure and primary output, in particular, according to the deviation between the measured steam pressure of this steam generator and the average steam pressure of all steam generators, and the deviation between the measured primary output of this steam generator and the average primary output of all steam generators. - The characterization of the feedwater temperature imbalance in a steam generator is performed, for example, according to the primary output, and in particular, according to the deviation between the measured primary output of this steam generator and the average primary output of all steam generators. - The characterization of the feedwater flow rate imbalance in the steam generator is performed, for example, according to the water level in the steam generator, and in particular, according to the deviation between the measured water level and the set water level value in the steam generator. - The characterization of the purge flow rate imbalance of a steam generator is performed according to the feedwater rate of that steam generator, and in particular, according to the deviation between the measured feedwater flow rate of that steam generator and the average feedwater flow rate of all steam generators.

[0014] The present invention also relates to a nuclear power plant monitoring system comprising sensors for measuring parameters of a set of representative parameters for each steam generator, and to an electronic device configured for the execution of a monitoring method from measurements by such sensors as limited above.

[0015] The present invention also relates to a computer program product that is recordable on a memory or data storage medium and executable by a processor or computer, the computer program product including software code instructions for the execution of a monitoring method as limited above.

[0016] The present invention and its advantages will become apparent by reading the following detailed description, which is given by way of reference and not limitation, with reference to the accompanying drawings.

Brief Description of the Drawings

[0017] [Figure 1] It is a schematic diagram of a nuclear power plant having a monitoring system configured for the implementation of a monitoring method. [Figure 2] It is a block diagram showing the steps of a monitoring method. [Figure 3] It is a diagram showing an electronic monitoring unit of a monitoring system configured for the implementation of a monitoring method. [Figure 4] It is a diagram showing an electronic monitoring unit of a monitoring system configured for the implementation of a monitoring method. [Figure 5] It is a diagram showing an electronic monitoring unit of a monitoring system configured for the implementation of a monitoring method. [Figure 6] It is a diagram showing an electronic monitoring unit of a monitoring system configured for the implementation of a monitoring method.

Modes for Carrying Out the Invention

[0018] The nuclear power plant 2 shown in Figure 1 includes a primary water circulation circuit 4 and a secondary water circulation circuit 6, and the primary circuit 4 and the secondary circuit 6 are separated and thermally connected by N steam generators 8 (where N is an integer greater than or equal to 2, for example, 4).

[0019] Figure 1 shows a single steam generator 8 for the sake of simplifying the diagram.

[0020] Each steam generator 8 is positioned between the primary circuit 4 and the secondary circuit 6 and is configured for heat exchange between the water in the primary circuit 4 and the water in the secondary circuit 6.

[0021] Functionally, each steam generator 8 can generate steam within the secondary circuit 6, and within it, the steam generator 8 is supplied with liquid water at the inlet and provides gaseous water, i.e., steam, at the outlet.

[0022] The primary circuit 4 includes a reactor 10 for heating the water circulating within the primary circuit 4.

[0023] Nuclear power plant 2 is, for example, a pressurized water reactor (PWR), in which case reactor 10 is a pressurized water reactor (PWR), or a boiling water reactor (BWR), in which case reactor 10 is a boiling water reactor (BWR).

[0024] The primary circuit 4 comprises N primary fluid loops 12, each primary loop 12 fluidly coupling the reactor 10 to its respective steam generator 8.

[0025] The reactor 10 comprises a reactor vessel 14 and a core 16 consisting of a plurality of nuclear fuel assemblies 18 arranged in a row inside the reactor vessel 14.

[0026] The reactor 10 includes a control cluster 20 that can be lowered into the core 16 or raised out of the core 16 to control the reactivity of the reactor 10. The control cluster 20 includes, for example, control clusters that can be selectively inserted into the core 16 to reduce reactivity or withdrawn from the core 16 to increase reactivity, and shutdown clusters that can be generated in the core 16 to cause an automatic shutdown of the reactor 10.

[0027] Each primary loop 12 connects the reactor vessel 14 to its respective steam generator 8. Each primary loop 12 includes its own primary pump 22 for forcibly circulating water within that primary loop 12.

[0028] If the nuclear power plant 2 is a pressurized water reactor, the primary circuit 4 includes a pressurizer 24 configured to maintain sufficient pressure within the primary circuit 4 so that the water circulating within the primary circuit 4 remains in a liquid state.

[0029] The pressurizer 24 is fluid-coupled to the hot branch of the primary loop 12, that is, the branch where the fluid circulates from the reactor 10 toward the steam generator 8 located on this primary loop 12.

[0030] The secondary circuit 6 comprises N secondary loops 26, each of which is connected to its respective primary loop 12. Each steam generator 8 is positioned between the primary loop 12 and the coupled secondary loop 26.

[0031] The secondary circuit 6 includes one or more secondary pumps 28 for forcibly circulating the water within the secondary circuit 6. The secondary circuit 6 includes, for example, each secondary pump 28 within each secondary loop 26. Alternatively, one or more secondary pumps 28 supply all secondary loops 26.

[0032] The secondary circuit 6 includes a turbine 30 configured to convert the thermal energy contained in the steam circulating within the secondary circuit 6 into mechanical energy.

[0033] The inlet of the turbine 30 is connected to the secondary loop 26 via an inlet manifold (or "barrel") (not shown) configured to collect steam generated by the steam generator 8 and supply the collected steam to the turbine 30.

[0034] The secondary circuit 6 includes a condenser 32 configured to cool the steam, particularly from the turbine 30 and optionally from a steam bypass group (not shown), and to return the liquid water to a liquid state before sending it back to the steam generator 8 via the secondary loop 26.

[0035] The steam bypass group is part of a circuit that allows the turbine 30 to be bypassed depending on the desired steam flow rate through the turbine 30, between a steam collector (not shown) designed to collect steam coming from multiple steam generators 8 and a condenser 32.

[0036] The outlet of the condenser 32 is connected to the secondary loop 26 via an outlet collector (not shown) configured to distribute the water coming out of the condenser 32 to different secondary loops 26.

[0037] Each condenser 32 is, for example, located on the secondary circuit 6 and configured to perform heat exchange between the water in the secondary circuit 6 and the water circulating in the cooling circuit 34.

[0038] The nuclear power plant 2 includes a generator 36 mechanically coupled to the turbine 30 to generate electrical energy from the mechanical energy produced by the turbine 30. Electrical energy is supplied, for example, to the power distribution network.

[0039] Nuclear power plant 2 includes a monitoring system 40 configured for the automatic monitoring of nuclear power plant 2, in particular for the implementation of a monitoring method for nuclear power plant 2.

[0040] The monitoring system 40 includes sensors for measuring the operating parameters of the nuclear power plant 2, particularly parameters representing the operation of each steam generator 8.

[0041] The sensors include, for example, the following for each steam generator 8: - A primary water flow sensor 42 for measuring the water flow rate Q1 in the primary loop 12 in which the steam generator 8 is located. - An inflow water temperature sensor 44 for measuring the water temperature in the hot branch TC, i.e., the temperature of the water in the hot branch of the primary loop 12 that leads water from the reactor 10 to the steam generator 8. - Outflow water temperature sensor 46 for measuring the water temperature in the cold branch TF, i.e., the temperature of the water in the cold branch of the primary loop 12 that leads water from the steam generator 8 to the reactor 10. - A steam pressure sensor 48 for measuring the steam pressure PV, i.e., the steam pressure at the outlet of the steam generator 8 in the secondary loop 26 where the steam generator 8 is located. - A steam flow sensor 50 for measuring the steam flow rate DV, i.e., the steam flow rate at the outlet of the steam generator 8 in the secondary loop 26 where the steam generator 8 is located. - A feedwater temperature sensor 52 for measuring the feedwater temperature TE, i.e., the temperature of the liquid water reaching the steam generator 8 in the secondary loop 26 where the steam generator 8 is located. - A feedwater flow sensor 54 for measuring the feedwater flow rate DE, i.e., the flow rate of liquid water reaching the steam generator 8 in the secondary loop 26 located in the steam generator 8. - A purge flow sensor 56 measures the purge flow rate DP of the steam generator 8. The purge flow rate DP is the flow rate of liquid water extracted from the secondary side of the steam generator 8. This purge flow rate DP is relatively small, especially compared to the flow rate of steam extracted from the steam generator 8. - A water level sensor 58 on the side of the secondary loop 26 measures the water level NV, which is the level of liquid water in the steam generator 8.

[0042] Please note that in this patent application, unless otherwise specified, the term "flow rate" is used to refer to the mass flow rate of a fluid.

[0043] The monitoring system 40 includes an electronic monitoring unit 60 configured to monitor the nuclear power plant 2 by performing a monitoring method.

[0044] The electronic monitoring unit 60 is provided, for example, by sensors located on the nuclear power plant 2 and is configured to receive measurement signals indicating the operation of each steam generator 8, namely, for each steam generator 8, a primary water flow sensor 42, an inlet water temperature sensor 44, an outlet water temperature sensor 46, a steam pressure sensor 48, a steam flow sensor 50, a feedwater temperature sensor 52, a feedwater flow sensor 54, a purge flow sensor 56 and / or a water level sensor 58.

[0045] The electronic monitoring unit 60 is configured to, for example, for each steam generator 8, compare the measured value of this parameter of the steam generator 8 with the average value of this parameter of all steam generators to detect an imbalance in at least one parameter of the steam generator 8, and, in response to the measurement signal received by the electronic monitoring unit 60, characterize such an imbalance in accordance with at least one other operating parameter of the steam generator 8 by emitting a physical problem signal and a measurement deviation signal.

[0046] The electronic monitoring unit 60 is preferably configured to emit alarm and deviation signals in a manner that can be sensed by a human operator and / or optionally for automatic control of the primary circuit 4 and / or secondary circuit 6, in response to the detection of an imbalance in the parameter of one steam generator with respect to the average value of this parameter for the entire steam generator 8.

[0047] The electronic monitoring unit 60 is configured, for example, to control the control cluster 20 to adjust or check the reactor reactivity, to control each primary pump 22 to adjust or check the water flow rate in each primary loop 12 of the primary circuit 4, to control each secondary pump 28 to adjust or check the water flow rate and / or water temperature in each secondary loop 26 of the secondary circuit 6, to control each turbine 30 and / or each generator 36, and to adjust or check the steam flow rate and / or steam pressure in each loop 26 of the secondary circuit 6.

[0048] The electronic monitoring unit 60 includes, for example, a processor, memory, and an information processing device that includes one or more software applications, i.e., software code instructions that are recordable in memory or a computer data medium and are executable when recorded in memory. Alternatively or optionally, the electronic monitoring unit 60 may include, for example, programmable logic circuits (e.g., field-programmable gate arrays) and / or integrated circuits.

[0049] In the case of computer program products, they include software code instructions for implementing monitoring methods.

[0050] This monitoring method is preferably carried out during steady-state operation of the nuclear power plant 2, that is, during periods when the power generated by the reactor 10 is stable.

[0051] During operation, each steam generator 8 receives a primary output P1 from the primary circuit 4, extracts secondary power P2 to the secondary circuit 6, and supplies transmission power PS to the secondary circuit 6.

[0052] For each steam generator 8, the primary output P1 supplied to the steam generator 8 by the primary circuit 4 is a function of the water flow rate Q1 in the primary loop 12 supplying the steam generator 8, the water temperature in the hot branch TC of the primary loop 12, and the water temperature in the cold branch TF of the primary loop 12.

[0053] For each steam generator 8, the primary output P1 is, for example, Equation P1=K1×Q1×(TC-TF), It can be calculated according to the following formula, where Q1 is the water flow rate measured in the primary loop, TC is the water temperature in the hot branch of the primary loop, TF is the water temperature in the cold branch of the primary loop, and K1 is the proportionality constant.

[0054] In steady-state operation, the secondary power P2 and the transmitted power PS are substantially equal, and for each steam generator 8, the secondary power P2 is, for example, Equation P2=DV×HV+DP×HP-DE×HE, This is determined by the following, where DV is the flow rate of steam leaving the steam generator, HV is the steam enthalpy leaving the steam generator as a function of steam pressure and temperature at the steam generator outlet, DE is the feedwater flow rate, i.e., the flow rate of water entering the steam generator 8 of the secondary circuit 6 in liquid form, HE is the feedwater enthalpy as a function of pressure and temperature of the water entering the steam generator 8 in liquid form, DP is the purge flow rate, and HP is the purge enthalpy.

[0055] In steady-state operation, for each steam generator 8, the feedwater flow rate DE is equal to the sum of the steam flow rate DV and the purge flow rate DP, and therefore, The equation DV + DP = DE holds true.

[0056] Furthermore, each steam generator 8 has a liquid water level NV which must preferably conform to a set water level value NVcons.

[0057] For each steam generator 8, the set of parameters that describe the operation of this steam generator 8 includes one or more of the following parameters: These parameters are steam flow rate DV, steam pressure PV, feedwater flow rate DE, feedwater temperature TE, purge flow rate DP, liquid state water level NV, and primary output P1.

[0058] For each steam generator 8, the value of each parameter is a function of one or more measurements provided by the measuring sensors of the nuclear power plant 2, namely, for each steam generator 8, one or more of the measuring sensors: the primary water flow sensor 42, the inflow water temperature sensor 44, the outflow water temperature sensor 46 of the primary loop 12 where the steam generator 8 is located, the steam pressure sensor 48, the steam flow sensor 50, the feedwater temperature sensor 52, the feedwater flow sensor 54, the purge flow sensor 56, and / or the water level sensor 58 of the secondary loop 26 where the steam generator 8 is located.

[0059] Next, the measured parameters of the steam generator correspond to the measured parameters determined for the steam generator 8 in accordance with the measured values ​​provided by one or more of the measurement sensors of the nuclear power plant 2.

[0060] Furthermore, the average value of the parameter is the average of the measured values ​​of this parameter for all steam generators 8.

[0061] For each parameter, the suffix "mes" is added to indicate the measured value of this parameter for the steam generator 8 being considered, and the suffix "avg" is added to indicate the average value of this parameter for all steam generators 8.

[0062] As shown in Figure 2, the monitoring method includes the following for at least one parameter from the set of representative parameters, and for each steam generator 8: -In order to detect the imbalance of this parameter in this steam generator 8, the deviation is calculated as the difference between the measured value of this parameter in this steam generator 8 and the average value of this parameter in all steam generators 8, and, - Characterizing the imbalance of the parameters of the steam generator 8 in accordance with one or more parameters from a set of representative parameters in order to generate a physical problem signal indicating that there is a physical problem in the steam generator 8 affected by the imbalance, or a measurement deviation signal indicating a deviation in the measurement of the values ​​of the operating parameters of the steam generator 8 affected by the imbalance.

[0063] The monitoring method includes, for example, comparing the deviation of a parameter's measured value to its mean value at one or more comparison thresholds in order to determine a potential or actual imbalance.

[0064] In one embodiment, for each steam generator 8 and for at least one parameter of the set of representative parameters, characterization of the imbalance of this parameter in the steam generator 8 includes, for example, the following: -If the deviation between the measured value and the calculation for this parameter is less than the lower threshold associated with this parameter, or greater than the upper threshold associated with this parameter, and optionally, if the deviation between the measured value and the reference value for other parameters in a set of representative parameters filtered using a phase-leading filter is less than the lower threshold associated with these other parameters, or greater than the upper threshold associated with these other parameters, and the reference value is preferably selected from the average value calculated for the other parameters, or from the set values ​​of the other parameters, then a physical problem signal is emitted, and / or - Emitting a measurement deviation signal when the deviation between the measured value and the calculated value with respect to this parameter is less than the lower threshold associated with this parameter or greater than the upper threshold associated with this parameter, and optionally the deviation between the measured value and the reference value of other parameters in a set of representative parameters filtered using a phase-lead filter is not less than the lower threshold associated with these other parameters and not greater than the upper threshold associated with these other parameters, and the reference value is preferably selected from the mean value of the other parameters or the set value of the other parameters.

[0065] Such characterizations are performed, for example, on feedwater temperature TE, steam pressure PV, steam flow rate DV, and / or purge flow rate DP.

[0066] In this context, a phase-lead filter refers to a lead-delay filter configured to introduce a phase lead into the signal filtered by the filter.

[0067] In one embodiment, for each steam generator 8 and for at least one parameter of the set of representative parameters, characterization of the imbalance of this parameter in the steam generator 8 includes, for example, the following: - If the deviation between the measured value and the calculated mean value for this parameter is less than the negative lower threshold associated with the parameter, and the deviation between the measured value and the reference value for other parameters in a set of representative parameters filtered using an optional phase-leading filter is less than the negative lower threshold associated with the other parameters, and the reference value is preferably selected from the calculated mean value for the other parameters or the set value for the other parameters, then the first physical problem signal is transmitted. - If the deviation between the measured value and the calculated mean value for this parameter is less than the negative lower threshold associated with the parameter, and the deviation between the measured value and the reference value for any other parameter filtered using a phase-lead filter is not less than the negative lower threshold associated with the other parameter, then a first measurement deviation signal is transmitted. - If the deviation between the measured value and the calculated mean of this parameter is greater than the positive upper threshold associated with the parameter, and if the deviation between the measured value and the reference value of any other parameter filtered using a phase-lead filter is greater than the positive upper threshold associated with the other parameter, then a second physical problem signal is emitted, and / or -Emitting a second measurement deviation signal if the deviation between the measured value and the calculated mean value for this parameter is greater than a positive upper threshold associated with the parameter, and the deviation between the measured value and the reference value for any other parameter filtered using a phase-lead filter is not greater than a positive upper threshold associated with the other parameter.

[0068] Such characterization is performed, for example, on the feedwater flow rate DE of at least one steam generator 8, and another parameter considered for characterization is the water level NV of the liquid state within this steam generator 8.

[0069] Alternatively or optionally, for each steam generator 8 and for at least one parameter of the set of representative parameters, the characterization of the imbalance of this parameter in the steam generator 8 may include, for example, the following: - If the deviation between the measured value and the calculated mean value for this parameter is less than the negative lower threshold associated with the parameter, and the deviation between the measured value and the reference value for other parameters in a set of representative parameters filtered using an optional phase-leading filter is greater than the positive upper threshold associated with the other parameters, and the reference value is preferably selected from the calculated mean value for the other parameters or the set value for the other parameters, then the first physical problem signal is transmitted. - If the deviation between the measured value and the mean value calculated for this parameter is less than the negative lower threshold associated with the parameter, and the deviation between the measured value and the reference value of any other parameter filtered using a phase-leading filter is not greater than the positive upper threshold associated with the other parameter, then a first measurement deviation signal is transmitted. - If the deviation between the measured value and the calculated mean value for this parameter is greater than the positive upper threshold associated with the parameter, and the deviation between the measured value and the reference value for any other parameter filtered using a phase-leading filter is less than the negative lower threshold associated with the other parameter, then a second physical problem signal is emitted, and / or -Emitting a second measurement deviation signal if the deviation between the measured value and the calculated mean value for this parameter is greater than the positive upper threshold associated with the parameter, and the deviation between the measured value and the reference value for other parameters filtered using a phase-lead filter is not less than the negative lower threshold.

[0070] In one embodiment, the monitoring method includes generating an alarm signal when the deviation between a measured value of the parameter and, for example, a calculated average value of the parameter, or a reference value of the parameter selected from setpoints of the parameter filtered using an optional phase-leading filter, is less than an alarm lower threshold, and / or issuing an alarm signal when the deviation between a measured value and a reference value of the parameter filtered using an alarm upper threshold is greater than an alarm upper threshold.

[0071] In one embodiment, the monitoring method includes emitting a difference signal when the deviation between a measured value calculated for the parameter and a reference value for the parameter selected from, for example, an average value or optionally filtered using a phase-leading filter, is less than a lower deviation threshold, and / or generating a deviation signal when the deviation between a measured value and optionally filtered using a phase-leading filter, is greater than an upper deviation threshold.

[0072] For characterizing imbalances using a comparison of the deviation between a measured value and a reference value for a parameter (e.g., the mean value calculated for this parameter or the set value for this parameter) with lower and upper thresholds (e.g., a negative threshold and a positive threshold), the same deviation signal or alarm signal may be issued as soon as the deviation between the measured value and the reference value falls below the lower threshold or exceeds the upper threshold. A first deviation signal or first alarm signal may be issued if the deviation falls below the lower threshold, and a second deviation signal or second alarm signal may be issued if the deviation exceeds the upper threshold.

[0073] When making comparisons, particularly to take into account the characterization of imbalances in other parameters of a set of representative parameters, using a phase-lead filter applied to the deviation between the measured value and the reference value allows us to predict whether this deviation will pass a threshold, i.e., fall below the lower threshold or exceed the upper threshold.

[0074] In particular, for each steam generator 8 and for at least one parameter of the set of representative parameters, a deviation threshold can be used, for example, to generate a deviation signal used for characterizing imbalances in this parameter, and an alarm threshold can be used for detecting imbalances in other parameters of the steam generator and for generating an alarm signal used for characterizing imbalances in the said parameter.

[0075] For the same parameter, each deviation threshold is preferably equal to or greater than the corresponding alarm threshold in absolute value.

[0076] Therefore, a small deviation in the value of one steam generator parameter can trigger the activation of an alarm signal, which can be used to characterize an imbalance that leads to a larger deviation in the value of another steam generator parameter.

[0077] Small deviations in this parameter do not necessarily require the emission of a physical problem signal or deviation signal for this parameter, but they allow for the characterization of imbalances in other parameters and the determination of whether deviations in these other parameters are related to a physical problem or measurement deviation.

[0078] In one embodiment, for each steam generator 8, characterization of the imbalance of one parameter is performed, for example, in response to one or more alarm signals and / or one or more deviation signals transmitted to each of the other parameters considered to detect potential imbalances between this parameter and the parameters under consideration, in accordance with the conditions described above, and using, for example, logic gates ("OR" gates, "AND" gates, inverter gates), truth tables, or software code instructions that encode the conditions described above.

[0079] The set of parameters describing the operation of the steam generator 8 includes, for example, for each steam generator 8, the water flow rate Q1 in the primary loop 12, the water temperature in the cold branch TF of the primary loop 12, and the primary output P1 which is a function of the water temperature in the hot branch TC of the primary loop 12.

[0080] In one embodiment, the primary output P1 is used to characterize the imbalance of at least one other parameter between a set of representative parameters.

[0081] Next, the monitoring method, as shown in Figure 3, includes calculating the measured primary output P1mes for each steam generator 8 (by the primary output calculation formula described above) according to the measured water flow rate Q1mes, the measured water temperature TFmes in the cold loop, and the measured water temperature TCmes in the hot branch, and calculating the average primary output P1avg as the average of the measured primary outputs P1mes.

[0082] For each steam generator 8, the monitoring method includes calculating the primary output deviation ΔP1 as the difference between the measured primary output P1mes and the average primary output P1avg for that steam generator 8.

[0083] For each steam generator 8, the monitoring method includes generating a primary output alarm signal ALP1 when the primary output deviation ΔP1, after being filtered using an optional primary output phase lead filter FP1, falls below the primary output alarm lower threshold SALP1inf or exceeds the primary output alarm upper threshold SALP1sup.

[0084] In one embodiment, the monitoring method includes calculating a steam pressure deviation ΔPV for each steam generator 8 as the difference between the measured steam pressure PVmes of that steam generator 8 and the average steam pressure PVavg of all steam generators 8, and calculating a steam flow deviation ΔDV as the difference between the measured steam flow rate DVmes of that steam generator 8 and the average steam flow rate DVavg of all steam generators 8.

[0085] For each steam generator 8, the characterization of the imbalance in the steam pressure PV of this steam generator 8 includes, for example, the following: - The steam pressure physical problem signal PPPV is issued when the steam pressure deviation ΔPV of this steam generator 8 is less than the lower limit threshold SECPVinf or greater than the upper limit threshold SECPVsup, and further, when the steam flow deviation ΔDV of this steam generator 8, optionally filtered using a steam flow phase-leading filter FDV, is less than the lower limit threshold SALDVinf or greater than the upper limit threshold SALDVsup, or when the primary output deviation ΔP1 of this steam generator 8, optionally filtered using a primary output phase-leading filter FP1, is less than the lower limit threshold SALP1inf or greater than the upper limit threshold SALP1sup, and / or - The steam pressure measurement deviation signal DMPV is emitted when the steam pressure deviation ΔPV of this steam generator 8 is less than the lower limit threshold SECPVinf or greater than the upper limit threshold SECPVsup, and optionally the steam flow deviation ΔDV of this steam generator 8, filtered using the steam flow phase leading filter FDV, is not less than the lower limit threshold SALDVinf for steam flow alarms and is not greater than the upper limit threshold SALDVsup for steam flow alarms, and optionally the primary output deviation ΔP1 of this steam generator 8, filtered using the primary output phase leading filter FP1, is not less than the lower limit threshold SALP1inf for primary output alarms and is not greater than the upper limit threshold SALP1sup for primary output alarms.

[0086] For each steam generator 8, the characteristic evaluation of the imbalance in the steam flow rate DV of this steam generator 8 includes, for example, the following: - The steam flow physical problem signal PPDV is issued if the steam flow deviation ΔDV of this steam generator 8 is less than the lower limit threshold SECDVinf or greater than the upper limit threshold SECDVsup, and further, if the steam pressure deviation ΔPV of this steam generator 8, filtered optionally using a steam pressure phase-leading filter FPV, is less than the lower limit threshold SALPVinf or greater than the upper limit threshold SALPVsup, or if the primary output deviation ΔP1 of this steam generator 8, filtered optionally using a primary output phase-leading filter FP1, is less than the lower limit threshold SALP1inf or greater than the upper limit threshold SALP1sup, and / or - The steam flow measurement deviation signal DMDV is emitted when the steam flow deviation ΔDV of this steam generator 8 is less than the lower limit threshold SECDVinf of the steam flow deviation or greater than the upper limit threshold SECDVsup of the steam flow deviation, and optionally, the steam pressure deviation ΔPV of this steam generator 8, filtered using a phase-leading filter, is not less than the lower limit threshold SALPVinf of the steam pressure alarm and is not greater than the upper limit threshold SALPVsup of the steam pressure alarm, and optionally, the primary output deviation ΔP1 of this steam generator 8, filtered using a primary output phase-leading filter FP1, is not less than the lower limit threshold SALP1inf of the primary output alarm and is not greater than the upper limit threshold SALP1sup of the primary output alarm.

[0087] It is preferable that the deviation threshold and alarm threshold considered for characterizing the imbalance in steam pressure (PV) are different.

[0088] Preferably, the absolute value of each deviation threshold (lower vapor pressure deviation threshold SECPVinf and upper vapor pressure deviation threshold SECPVsup) is greater than or equal to the absolute value of the corresponding alarm threshold (lower vapor pressure alarm threshold SALPVinf and upper vapor pressure alarm threshold SALPVsup, respectively).

[0089] It is preferable that the deviation threshold and alarm threshold considered for characterizing the imbalance in steam flow rate DV are different.

[0090] Preferably, the absolute value of each deviation threshold (lower steam flow deviation threshold SECDVinf and upper steam flow deviation threshold SECDVsup) is greater than or equal to the absolute value of the corresponding alarm threshold (lower steam flow alarm threshold SALDVinf and upper steam flow alarm threshold SALDVsup, respectively).

[0091] In one embodiment, the monitoring method includes the following for each steam generator 8. - If the primary output deviation ΔP1 of this steam generator 8, filtered using an optional primary output phase lead filter FP1, is less than the primary output alarm lower threshold SALPinf or greater than the primary output alarm upper threshold SALP1sup, the primary output alarm signal ALP1 is issued. - The steam pressure alarm signal ALPV is issued when the steam pressure deviation ΔPV of this steam generator 8, optionally filtered using a steam pressure phase lead filter FPV, is less than the steam pressure alarm lower threshold SALPVinf or greater than the steam pressure alarm upper threshold SALPVsup. - The steam pressure deviation signal ECPV is emitted when the steam pressure deviation ΔPV of this steam generator 8 is less than the lower limit threshold SECPVinf or greater than the upper limit threshold SECPVsup. - If the steam flow deviation ΔDV of this steam generator 8, filtered optionally using a steam flow phase lead filter FDV, is less than the steam flow alarm lower threshold SALDVinf or greater than the steam flow upper threshold SALDVsup, a steam flow alarm signal ALDV is issued, and / or, - The steam flow deviation signal ECDV is emitted when the steam flow deviation ΔDV of this steam generator 8 is less than the lower limit threshold SECDVinf or greater than the upper limit threshold SECDVsup.

[0092] In one embodiment, for each steam generator 8, characterization of imbalances with respect to steam pressure PV or steam flow rate DV is performed, for example, in response to alarm signals (ALP1, ALPV, ALDV) and deviation signals (ECPV, ECDV), and using, for example, logic gates ("OR" gates, "AND" gates, inverter gates), truth tables, or software code instructions that encode the conditions shown above, according to the conditions described above.

[0093] Figure 3 shows an electronic monitoring unit 60 configured to use logic gates to characterize steam pressure imbalance or steam flow rate imbalance in response to one or more alarm signals and one or more deviation signals.

[0094] As shown in Figure 3, the electronic monitoring unit 60 includes, for each steam generator 8, a primary output differential comparator 62 for calculating the primary output deviation ΔP1, a steam pressure differential comparator 64 for calculating the steam pressure deviation ΔPV, and a steam flow differential comparator 66 for calculating the steam flow deviation ΔDV.

[0095] The electronic monitoring unit 60 further includes a primary output alarm threshold comparator 68 for transmitting a primary output alarm signal ALP1, a steam pressure alarm threshold comparator 70 for transmitting a steam pressure alarm signal ALPV, a steam pressure deviation threshold comparator 72 for transmitting a steam pressure deviation signal ECPV, a steam flow alarm threshold comparator 74 for transmitting a steam flow alarm signal ALDV, and / or a steam flow deviation threshold comparator 76 for transmitting a steam flow deviation signal ECDV.

[0096] Each threshold comparator emits a corresponding alarm signal or deviation signal in the form of a logical signal, depending on the emission conditions described above.

[0097] The electronic monitoring unit 60 includes logic gates for emitting physical problem signals PPPV, PPDV and measurement deviation signals DMPV, DMDV in response to alarm signals and deviation signals emitted by threshold comparators, according to the criteria described above.

[0098] In one embodiment, the monitoring method includes calculating the feedwater temperature deviation ΔTE for each steam generator 8 as the difference between the measured feedwater temperature TEmes for that steam generator 8 and the average feedwater temperature TEavg for all steam generators 8.

[0099] For each steam generator 8, the characteristic evaluation of the feedwater temperature imbalance in this steam generator 8 includes, for example, the following: -If the feedwater temperature deviation ΔTE of this steam generator 8 is less than the feedwater temperature deviation lower threshold SECTEinf or greater than the feedwater temperature deviation upper threshold SECTEsup, and the primary output deviation ΔP1 of this steam generator 8 is less than the primary output alarm lower threshold SALP1inf or greater than the primary output alarm upper threshold SALP1sup, a feedwater temperature physical problem signal PPTE is issued, and / or, - The feedwater temperature measurement deviation signal DMTE is issued when the feedwater temperature deviation ΔTE of the steam generator 8 is less than the feedwater temperature deviation lower threshold SECTEinf or greater than the feedwater temperature deviation upper threshold SECTEsup, and the primary output deviation ΔP1 of the steam generator 8 is not less than the primary output alarm lower threshold SALP1inf or greater than the primary output alarm upper threshold SALP1sup.

[0100] In one embodiment, the monitoring method includes the transmission of a feedwater temperature deviation signal ECTE for each steam generator 8 when the feedwater temperature deviation ΔTE is less than the feedwater temperature deviation lower threshold SECTEinf or greater than the feedwater temperature deviation upper threshold SECTEsup.

[0101] The monitoring method includes, for example, characterizing the imbalance with respect to feedwater temperature for each steam generator 8, in accordance with the conditions described above, the feedwater temperature deviation signal ECTE and the primary output alarm signal ALP1, and using, for example, logic gates ("OR" gates, "AND" gates, inverter gates, etc.), truth tables, or software code instructions that encode the conditions described above.

[0102] Alternatively, the monitoring method includes, for each steam generator 8, the issuance of a feedwater temperature alarm signal ALTE if the feedwater temperature deviation ΔTE, filtered using an optional feedwater temperature phase-leading filter FTE, is less than the feedwater temperature alarm lower threshold SALTEinf or greater than the feedwater temperature alarm upper threshold SALTEsup.

[0103] Each deviation threshold (lower water temperature deviation threshold SECTEinf and upper water temperature deviation threshold SECTEsup) and the corresponding alarm thresholds (lower water temperature alarm threshold SALTEinf and upper water temperature alarm threshold SALTEsup) are different, and it is preferable that the deviation thresholds are greater than or equal to the corresponding alarm thresholds in absolute value.

[0104] Figure 4 shows an electronic monitoring unit 60 configured to use logic gates to characterize the feedwater temperature imbalance of the steam generator 8 in response to alarm signals and deviation signals.

[0105] As shown in Figure 4, the electronic monitoring unit 60 includes a feedwater temperature differential comparator 78 for each steam generator 8 to calculate the deviation of the feedwater temperature of that steam generator 8.

[0106] The electronic monitoring unit 60 further includes a primary output alarm threshold comparator 80 for transmitting a primary output alarm signal ALP1, a water supply temperature alarm threshold comparator 82 for transmitting a water supply temperature alarm signal ALTE, and / or a water supply temperature deviation threshold comparator 84 for transmitting a water supply temperature deviation signal ECTE.

[0107] Each threshold comparator emits a corresponding alarm signal or deviation signal according to the aforementioned emission conditions.

[0108] The electronic monitoring unit 60 includes logic gates for emitting physical problem and measurement deviation signals in accordance with the alarm signal and deviation signal determined by the threshold comparator, according to the conditions described above.

[0109] The monitoring method includes, for example, calculating the feedwater flow deviation ΔDE for each steam generator 8 as the difference between the measured feedwater flow rate DEmes for that steam generator 8 and the average feedwater flow rate DEavg for all steam generators 8.

[0110] The monitoring method further includes calculating the water level deviation ΔNV for each steam generator 8 as the difference between the measured water level value NVmes and the set water level value NVcons for that steam generator 8.

[0111] For each steam generator, the characteristics of the feedwater flow rate imbalance of this steam generator 8 are evaluated, for example, according to the feedwater flow rate deviation ΔDE and water level deviation ΔNV from this steam generator 8.

[0112] In one embodiment, the characteristics evaluation of the feedwater flow rate imbalance of each steam generator 8 includes the following: -Emission of a low water flow physical problem signal PPDEneg when the water flow deviation ΔDE is less than the negative water flow deviation threshold SECDEneg, and the water level deviation ΔNV filtered using the water level phase lead filter FNV is less than the negative water level alarm threshold SALNVneg. -Emitting a small water supply flow measurement deviation signal DMDEneg when the water supply flow deviation ΔDE is smaller than the negative water supply flow deviation threshold SECDEneg, and in some cases the water level deviation ΔNV filtered using the water level phase lead filter FNV is not smaller than the negative water level alarm threshold SALNVneg. -If the water supply flow deviation ΔDE is greater than the positive water supply flow deviation threshold SECDEpos, and optionally the water level difference filtered using the water level phase lead filter FNV is greater than the positive water level alarm threshold SALNVpos, a large water supply flow physical problem signal PPDEpos is issued, and / or, - A large water supply flow measurement deviation signal DMDEpos is issued when the water supply flow deviation ΔDE is greater than the positive water supply flow deviation threshold SECDEpos, and the water level deviation ΔNV filtered using an optional water level phase lead filter FNV is not greater than the positive water level alarm threshold SALNVpos.

[0113] In one embodiment, the monitoring method includes the following for each steam generator 8. - When the water supply flow deviation ΔDE is smaller than the negative water supply flow deviation threshold SECDEneg, a negative water supply flow deviation signal ECDeneg is emitted. - When the water supply flow deviation ΔDE is greater than the positive water supply flow deviation threshold SECDEpos, a positive water supply flow deviation signal ECDEpos is emitted. - If the feedwater flow deviation ΔDE filtered using the optional feedwater flow phase lead filter FDE is less than the negative feedwater flow alarm threshold SALDEneg, a negative feedwater flow alarm signal ALDEneg is issued. - If the feedwater flow deviation ΔDE filtered using the optional feedwater flow phase lead filter FDE is greater than the positive feedwater flow alarm threshold SALDEpos, a positive feedwater flow alarm signal ALDEpos is issued, and / or, - The emission of a comparative flow deviation signal ECDE when the feedwater flow deviation ΔDE, filtered using an optional comparative flow phase-leading filter FDC, is less than the comparative flow deviation lower threshold SECDCinf or greater than the comparative flow deviation upper threshold SECDCsup.

[0114] Furthermore, as shown in Figure 5, the method includes, for example, issuing a negative water level deviation alarm signal ALNVneg if the water level deviation ΔNV filtered using an optional water level phase-leading filter FNV is smaller than the negative water level alarm threshold SALNVneg, and issuing a positive water level deviation alarm signal ALNVpos if the water level deviation ΔNV filtered using an optional water level phase-leading filter FNV is larger than the positive water level alarm threshold SALNVpos.

[0115] Preferably, each water supply flow rate deviation threshold (negative water supply flow rate deviation threshold and positive water supply flow rate deviation threshold) and the corresponding alarm threshold (negative water supply flow alarm threshold and positive water supply flow alarm threshold, respectively) are different. In particular, it is preferable that each deviation threshold is greater than the corresponding alarm threshold in absolute value.

[0116] The monitoring method includes, for example, characterizing the imbalance with respect to the feedwater flow rate DE for each steam generator 8, in accordance with the conditions described above and using, for example, logic gates ("OR" gates, "AND" gates, inverter gates), truth tables, or software code instructions that encode the conditions described above, in response to deviation signals with respect to the feedwater flow rate DE (negative feedwater flow rate deviation signal ECDEneg and positive feedwater flow rate deviation signal ECDEpos), and in response to alarm signals with respect to the water level (negative water level deviation alarm signal ALNVneg and positive water level deviation alarm signal ALNVpos).

[0117] In one embodiment, the monitoring method includes calculating the purge flow deviation ΔDP for each steam generator 8 as the difference between the measured purge flow rate DPmes of that steam generator 8 and the average purge flow rate DPavg of all steam generators 8.

[0118] For each steam generator 8, the monitoring method includes, for example, the following: - If the purge flow deviation ΔDP is below the lower limit threshold SECDPinf of the purge flow deviation or above the upper limit threshold SECDPsup of the purge flow deviation, and optionally, if the feedwater flow deviation ΔDE of this steam generator 8, filtered using the comparative flow phase lead filter FDC, is less than the lower limit threshold SECDCinf of the comparative flow deviation or greater than the upper limit threshold SECDCsup of the comparative flow deviation, then a purge flow physical problem signal PPDP is emitted, and / or, -Emission of a purge flow measurement deviation signal DMDP if the purge flow deviation ΔDP of this steam generator is below the lower limit threshold SECDPinf of the purge flow deviation or above the upper limit threshold SECDPsup of the purge flow deviation, and optionally, the feedwater flow deviation ΔDE of this steam generator 8, filtered using a comparative flow phase lead filter FDC, is not less than the lower limit threshold SECDCinf of the comparative flow deviation and not greater than the upper limit threshold SECDCsup of the comparative flow deviation.

[0119] In particular, if the monitoring method includes the possibility of whether or not a comparative flow rate deviation signal ECDC is transmitted (i.e., not present) according to the above conditions, the monitoring method includes, for example, the following for each steam generator 8: - If the purge flow deviation ΔDP is below the lower limit threshold SECDPinf or above the upper limit threshold SECDPsup, and a comparative flow deviation signal ECDC is present, the purge flow physical problem signal PPDP is transmitted, and / or - The purge flow measurement deviation signal DMDP is emitted when the purge flow deviation ΔDP of this steam generator falls below the lower limit threshold SECDPinf or exceeds the upper limit threshold SECDPsup, and when the comparative flow deviation signal ECDC is not present.

[0120] In one embodiment, the monitoring method includes the transmission of a purge flow deviation signal ECDP when the purge flow deviation ΔDP falls below the lower limit threshold SECDPinf of the purge flow deviation or exceeds the upper limit threshold SECDPsup of the purge flow deviation.

[0121] Furthermore, the monitoring method includes, for example, characterizing the purge flow imbalance in accordance with the purge flow deviation signal ECDP and the comparison flow deviation signal ECDC for each steam generator 8, in accordance with the conditions described above and using, for example, logic gates ("OR" gates, "AND" gates, inverter gates, etc.), truth tables, or instructions in software code that encode the conditions described above.

[0122] Optionally, the monitoring method includes, for each steam generator 8, the activation of a purge flow alarm signal ALDP when the purge flow deviation ΔDP, filtered using an optional purge flow phase lead filter FDP, is less than the purge flow alarm lower threshold SALDPinf or greater than the purge flow alarm upper threshold SALDPsup.

[0123] Preferably, each deviation threshold (lower purge flow deviation threshold SECDPinf and upper purge flow deviation threshold SECDPsup) is greater than or equal to the corresponding alarm threshold (lower purge flow alarm threshold SALDPinf and upper purge flow alarm threshold SALDPsup) in absolute value.

[0124] Figures 5 and 6 show an electronic monitoring unit 60 configured to implement a monitoring method, using logic gates to characterize imbalances in feedwater flow rate and / or purge flow rate of steam generator 8, in particular, in response to one or more alarm signals and one or more deviation signals.

[0125] As shown in Figures 5 and 6, the electronic monitoring unit 60 includes, for each steam generator 8, a feedwater flow differential comparator 90 (Figure 5) for calculating the feedwater flow rate deviation of the steam generator 8, a water level flow differential comparator 92 (Figure 5) for calculating the difference between the measured water level value NVmes and the set water level value NVcons of the steam generator 8, and a purge flow differential comparator 93 (Figure 6) for calculating the purge flow rate deviation ΔDP of the steam generator 8.

[0126] The electronic monitoring unit 60 further includes a negative water supply flow deviation threshold comparator 94 for emitting a negative water supply flow deviation signal ECDeneg, a positive water supply flow deviation threshold comparator 96 for emitting a positive water supply flow deviation signal ECDepos, a negative water supply flow alarm threshold comparator 98 for emitting a negative water supply flow deviation alarm signal ALDeneg, a positive water supply flow alarm threshold comparator 100 for emitting a positive water supply flow deviation alarm signal ALDepos, a comparative flow threshold comparator 102 for emitting a comparative flow deviation signal ECDC, a negative water level threshold comparator 104 for emitting a negative measured-to-set water level difference alarm signal ALDneg, and / or a positive water level threshold comparator 106 for emitting a positive measured-to-set water level difference alarm signal ALDneg (Figure 5).

[0127] The electronic monitoring unit 60 further includes a purge flow alarm threshold comparator 108 for transmitting a purge flow alarm signal ALDP and a purge flow deviation threshold comparator 110 for transmitting a purge flow deviation signal ECDP (Figure 6).

[0128] Each threshold comparator emits a corresponding alarm signal or deviation signal according to the aforementioned emission conditions.

[0129] The electronic monitoring unit 60 includes logic gates for emitting physical problem signals and measurement deviation signals in response to alarm signals and deviation signals determined by a threshold comparator according to the criteria described above.

[0130] By comparing the measured values ​​of the parameters of steam generator 8 with the average values ​​of these parameters for all steam generators 8, it becomes possible to identify any imbalance in these parameters of steam generator 8 compared to other steam generators 8.

[0131] Such imbalances may be due to physical problems with the steam generator 8, namely, actual problems present in the steam generator 8 that are affected by the imbalance, or to measurement deviations of the aforementioned parameters of the steam generator 8.

[0132] Each other parameter considered for characterizing the imbalance detected on the parameter is preferably another parameter linked to the parameter on which the imbalance is detected and which is also affected by the imbalance.

[0133] Therefore, as mentioned above, -The characterization of the steam pressure imbalance in steam generator 8 is performed, for example, depending on the steam flow rate and primary output, in particular, depending on the deviation between the measured steam flow rate DVmes of steam generator 8 and the average steam flow rate DVavg of steam generator 8, and the deviation between the measured primary output P1mes of steam generator 8 and the average primary output P1avg of all steam generators 8. -The characterization of the steam flow rate imbalance in steam generator 8 is performed, for example, according to the steam pressure and primary output, in particular according to the deviation between the measured steam pressure PVmes of this steam generator 8 and the average steam pressure PVavg of all steam generators 8, and according to the deviation between the measured primary output P1mes of this steam generator 8 and the average primary output P1avg of all steam generators 8. -The characterization of the feedwater temperature imbalance in the steam generator 8 is performed, for example, according to the primary output, and in particular according to the deviation between the measured primary output P1mes of this generator steam 8 and the average primary output P1avg of all steam generators 8. -The characterization of the feedwater flow rate imbalance of the steam generator 8 is performed, for example, according to the water level of the steam generator 8, in particular according to the deviation between the measured water level value NVmes and the set water level value NVcons of the steam generator 8, and / or - The characterization of the purge flow rate imbalance in steam generator 8 is performed, for example, according to the feedwater flow rate of this steam generator 8, and in particular according to the deviation between the measured feedwater flow rate DEmes of this steam generator 8 and the average feedwater flow rate DEavg of all steam generators 8.

[0134] By characterizing the parameter imbalance of the steam generator 8 in relation to one or more other parameters, the monitoring system 40 can automatically generate a signal indicating that the detected imbalance is due to a physical problem with the steam generator or a measurement deviation of this parameter of the steam generator.

[0135] Each alarm signal, each deviation signal, each physical problem signal, and / or each measurement deviation signal makes it possible to detect actual or potential imbalances between the steam generators 8.

[0136] Using phase-leading filters in processing measurements provided by several sensors makes it possible to predict potential problems, in particular, allowing human operators to better prepare for the emergence of more significant deviations in specific parameters.

[0137] Each alarm signal, each deviation signal, each physical problem signal, and / or each measurement deviation signal associated with a parameter is determined according to one or more other parameters, thereby enabling the timely generation of said signals.

[0138] Preferably, at least one of the following parameters, in particular each of which may lead to the generation of alarm signals, deviation signals, physical problem signals, and / or measurement deviation signals, is subject to characterization. These parameters are steam pressure PV, steam flow rate DV, feedwater temperature TE, feedwater flow rate DE, and purge flow rate DP.

[0139] Each of these parameters is characterized by considering another parameter, making it possible to optionally detect in advance the emergence of imbalances in the operation of the steam generator.

[0140] In one embodiment, each alarm signal, each deviation signal, each physical problem signal, and / or each measurement deviation signal are transmitted in the form of, for example, visual signals, audible signals, and / or tactile signals so that they can be perceived by a human operator. Therefore, the operator can take the necessary measures.

[0141] Each alarm signal, each deviation signal, each physical problem signal, and / or each measurement deviation signal, which are transmitted in a manner perceptible to a human operator, are transmitted, for example, via a human-machine interface. Human-machine interfaces include, for example, display screens, control panels, and / or sound generators.

[0142] After the characterization of the imbalance has been confirmed, if the operator or monitoring system is configured to control nuclear power plant 2, it will be possible to take appropriate measures following the detection and confirmation of the imbalance, depending on whether it is a physical problem or a measurement deviation.

[0143] If physical problems are characterized, the nuclear power plant 2 can be controlled to put the nuclear power plant 2 into an operating mode that compensates for the physical problems or allows the physical problems to be corrected.

[0144] If the measurement deviation is characterized, it is possible to take the deviation into account and correct the measurement signal provided by the sensor in question, or to inspect (repair or replace) the faulty equipment while it is in operation or in a shutdown state.

[0145] The monitoring method according to the present invention makes it possible to provide human operators with assistance in controlling nuclear power plants.

[0146] Each alarm signal, each deviation signal, each physical problem signal, and / or each measurement deviation signal, which are emitted in a manner perceptible to human operators, can alert human operators if one of the steam generators 8 of the nuclear power plant 2 is operating in an unbalanced manner.

[0147] Each alarm signal, each deviation signal, each physical problem signal, and / or each measurement deviation signal emitted to attract the attention of a human operator helps the human operator establish a diagnosis by enabling them to pinpoint, for example, the origin of the reported problem (i.e., to determine which part of Nuclear Power Plant 2 the origin of the reported problem is) and the cause of the reported problem (i.e., what is the reason for the reported problem, whether it is a physical problem or a measurement deviation).

[0148] Each alarm signal, each deviation signal, each physical problem signal, and / or each measurement deviation signal transmitted in a manner perceptible to human operators helps to search for potential leaks in the primary or secondary circuitry and / or to warn human operators if one of the steam generators 8 of the nuclear power plant 2 is operating in an unbalanced manner. [Explanation of Symbols]

[0149] 2. Nuclear power plants 4 Primary water circulation circuit 6 Secondary water circulation circuit 8. Steam generator 10 nuclear reactor 12 Primary fluid loop 14 Reactor vessel 16 Core 18 Nuclear fuel assembly 20 Control Clusters 22 Primary pump 24 Pressurizer 26 Second-order loop 28 Secondary pump 30 Turbine 32 Condenser 34 Cooling circuit 36 Generators 40 Monitoring Systems 42 Primary water flow sensor 44 Inflow water temperature sensor 46. ​​Outflow water temperature sensor 48. Steam pressure sensor 50 Steam flow sensor 52 Water supply temperature sensor 54 Water supply flow sensor 56 Purge flow sensor 58 Water level sensor 60 Electronic monitoring units 62 Primary Output Differential Comparator 64. Vapor Pressure Differential Comparator 66 Steam flow differential comparator 68 Primary Output Alarm Threshold Comparator 70. Steam pressure alarm threshold comparator 72. Steam pressure deviation threshold comparator 74. Steam Flow Alarm Threshold Comparator 76. Steam flow rate deviation threshold comparator 78 Water supply temperature differential comparator 80 Primary Output Alarm Threshold Comparator 82. Water supply temperature alarm threshold comparator 84. Water supply temperature deviation threshold comparator 90 Water supply flow differential comparator 92 Water level-flow differential comparator 93 Purge Flow Differential Comparator 94 Negative Water Supply Flow Rate Deviation Threshold Comparator 96 Positive water supply flow rate deviation threshold comparator 98 Negative Water Flow Alarm Threshold Comparator 100 Positive water supply flow alarm threshold comparator 102 Comparative Flow Threshold Comparator 104 Negative water level threshold comparator 106 Positive water level threshold comparator 108 Purge Flow Alarm Threshold Comparator 110 Purge Flow Deviation Threshold Comparator

Claims

1. A method for monitoring a nuclear power plant (2) performed by a monitoring system (40), The nuclear power plant (2) has a primary circuit (4), a secondary circuit (6), a reactor (10) located in the primary circuit (4) to heat the water circulating in the primary circuit (4), and N steam generators (8) arranged to transfer heat from the primary circuit (4) to the secondary circuit (6) by generating steam in the secondary circuit (6), The monitoring system (40) is equipped with a sensor for measuring parameters from a set of representative parameters for the operation of each steam generator (8) for each steam generator (8). The monitoring method involves monitoring at least one parameter from the set of representative parameters, and each steam generator (8), - In accordance with the measurements provided by the sensor, the deviation between the measured value of the parameter of this steam generator (8) and the average value of this parameter for all steam generators (8) is determined, and an imbalance in this parameter is detected in the steam generator (8), and, - Characterize the imbalances affecting the parameters of the steam generator (8) in accordance with one or more other parameters in a set of representative parameters, and generate a physical problem signal indicating the presence of a physical problem in the steam generator (8) affected by the imbalance, or a measurement deviation signal indicating the measurement deviation of the parameters considered in the steam generator (8) affected by the imbalance. A monitoring method that includes this.

2. For at least one parameter of the aforementioned set of representative parameters, Characterization of imbalances in one or more of the aforementioned parameters is performed for at least one or each of the other parameters, in accordance with the deviation between the measured value of the other parameter of the steam generator (8) under consideration and the reference value of the other parameter for all of the steam generators (8). The monitoring method according to claim 1, wherein the reference value is selected from the average value of the other parameters and the set value of the other parameters.

3. This includes detecting imbalances in this parameter or in other parameters by comparing at least one or each deviation between the measured value of the parameter and a reference value with one or more comparison thresholds, The monitoring method according to claim 1 or 2, characterized in that the reference value is selected from the average value and set value of the parameter.

4. For at least one parameter within the set of representative parameters, the following is used to characterize the imbalance in the parameters of the steam generator (8) under consideration: - A physical problem signal is emitted when the deviation between the measured value and the calculated mean for this parameter is less than the lower threshold associated with this parameter or greater than the upper threshold associated with this parameter, and when the deviation between the measured value and the reference value of another parameter in the set of representative parameters is less than the lower threshold associated with that other parameter or greater than the upper threshold associated with that other parameter, and / or - If the calculated deviation for this parameter is less than the lower threshold associated with this parameter, or greater than the upper threshold associated with this parameter, and the deviation between the measured value and the reference value of another parameter in the set of representative parameters is not less than the lower threshold associated with this other parameter, and is not greater than the upper threshold associated with this other parameter, then the measured deviation signal is emitted. The monitoring method according to claim 1, including the method described in claim 1.

5. - In the step of transmitting a physical problem signal, the reference value of another parameter in the set of representative parameters is selected from the average value calculated for the other parameter and the set value of the other parameter, and / or - The monitoring method according to claim 4, wherein in the step of transmitting a measurement deviation signal, the reference value of other parameters in the set of representative parameters is selected from the average value calculated for the other parameters and the set value of the other parameters.

6. For each of the aforementioned steam generators (8), and for at least one parameter of the set of representative parameters, the following is used to characterize the imbalance of this parameter in the steam generator (8): - The first physical problem signal is emitted when the deviation between the measured value and the calculated mean of this parameter is less than a negative lower threshold, and the deviation between the measured value and the reference value of this other parameter in the set of representative parameters is less than a negative lower threshold. - If the deviation between the measured value and the calculated mean for this parameter is less than a negative lower threshold, and the deviation between the measured value and the reference value of other parameters is not less than a negative lower threshold, then a first measurement deviation signal is transmitted. - If the deviation between the measured value and the calculated mean of this parameter is greater than a positive upper threshold, and if the deviation between the measured value and the reference value of other parameters is greater than a positive upper threshold, a second physical problem signal is emitted, and / or - If the deviation between the measured value and the calculated mean for this parameter is greater than a positive upper threshold, and the deviation between the measured value and the reference value of other parameters is not greater than a positive upper threshold, a second measurement deviation signal is transmitted. The monitoring method according to claim 1, including the method described in claim 1.

7. The monitoring method according to claim 6, wherein in the step of transmitting a physical problem signal, other parameters of the set of representative parameters are selected from the average value calculated for the other parameters and the set value of the other parameters.

8. The monitoring method according to claim 1, characterized in that, for each of the steam generators (8) and for at least one parameter of the set of representative parameters, an alarm signal is issued when the deviation between the measured value and the reference value is less than the lower alarm threshold, and / or when the deviation between the measured value and the reference value is greater than the upper alarm threshold, the reference value is selected from the average value of this parameter and the set value of this parameter.

9. The monitoring method according to claim 8, wherein the deviation between the measured value and the reference value is filtered using a phase-leading filter before being compared with an alarm lower threshold and / or an alarm upper threshold.

10. The monitoring method according to claim 9, characterized in that characterizing the imbalance of at least one parameter or each parameter of the set of representative parameters includes considering an alarm signal transmitted for another parameter of the set of representative parameters.

11. The monitoring method according to claim 1, wherein for each steam generator (8) and at least one parameter of the set of representative parameters, a deviation signal is transmitted when the deviation between the measured value and the reference value of this parameter is less than a lower deviation threshold, and / or a difference signal is transmitted when the deviation between the measured value and the reference value of this parameter is greater than an upper deviation threshold, and the reference value is selected from the average value of this parameter and the set value of this parameter.

12. - For each steam generator (8) and for at least one parameter of the set of representative parameters, a deviation signal is transmitted when the deviation between the measured value and the reference value of this parameter is less than a lower deviation threshold, and / or a deviation signal is transmitted when the deviation between the measured value and the reference value of this parameter is greater than an upper deviation threshold, the reference value being selected from the average value and the set value of this parameter, and The monitoring method according to claim 8, wherein the characterization of an imbalance in at least one parameter of the steam generator is performed in response to a deviation signal transmitted for that parameter and an alarm or deviation signal transmitted for at least one other parameter that takes the characterization into account.

13. The monitoring method according to claim 1, wherein for each of the steam generators, the set of representative parameters includes one or more of the following parameters: steam flow rate (DV), steam pressure (PV), feedwater flow rate (DE), feedwater temperature (TE), purge flow rate (DP), water level (NV), and primary output (P1).

14. The monitoring method according to claim 13, wherein the characteristic evaluation of the steam pressure imbalance of the steam generator (8) is performed according to the steam flow rate and primary output, in accordance with the deviation between the measured steam flow rate (DVmes) of the steam generator (8) and the average steam flow rate (DVavg) of the steam generator (8), and the deviation between the measured primary output (P1mes) of the steam generator (8) and the average primary output (P1avg) of all steam generators (8).

15. The monitoring method according to claim 13, wherein the characteristic evaluation of the imbalance in the steam flow rate of the steam generator (8) is performed according to the steam pressure and primary output, in accordance with the deviation between the measured steam pressure (PVmes) of the steam generator (8) and the average steam pressure (PVavg) of all steam generators (8), and the deviation between the measured primary output (P1mes) of the steam generator (8) and the average primary output (P1avg) of all steam generators (8).

16. The method according to claim 13, wherein the characteristic evaluation of the feedwater temperature (TE) imbalance of the steam generator (8) is performed according to the primary output.

17. The method according to claim 16, wherein the characteristic evaluation of the feedwater temperature (TE) imbalance of the steam generator (8) is performed according to the deviation between the measured primary output (P1mes) of the steam generator (8) and the average primary output (P1avg) of all steam generators (8).

18. The method according to claim 13, wherein the characteristic evaluation of the feedwater flow rate (DE) imbalance of the steam generator (8) is performed according to the water level of the steam generator (8).

19. The method according to claim 18, wherein the characteristic evaluation of the feedwater flow rate (DE) imbalance of the steam generator (8) is performed according to the deviation between the measured water level value (NVmes) and the set water level value (NVcons) of the steam generator (8).

20. The method according to claim 13, wherein the characteristic evaluation of the imbalance in the purge flow rate (DE) of the steam generator (8) is performed according to the feedwater flow rate of the steam generator (8).

21. The method according to claim 20, wherein the characteristic evaluation of the purge flow rate imbalance of the steam generator (8) is performed according to the deviation between the measured feedwater flow rate (DEmes) of the steam generator (8) and the average feedwater flow rate (DEavg) of all steam generators (8).

22. A nuclear power plant monitoring system comprising, for each of the steam generators (8), a sensor for measuring a set of representative parameters, and an electronic monitoring unit (60) configured for performing the monitoring method according to claim 1 based on the measurements provided by the sensor.

23. A computer program product that is recordable on memory or a data medium and executable by a processor or computer, comprising software code instructions for executing the monitoring method described in claim 1.

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