Reactor power determination method and system

Abstract

The present application relates to a reactor power determination method and system, the method comprising: periodically obtaining a plurality of steam generators respectively corresponding to the first main feed water flow and the second main feed water flow; according to the latest obtained first main feed water flow and the second main feed water flow, calculating the deviation coefficient corresponding to each steam generator; determining whether the deviation coefficient of each steam generator is less than the set deviation standard value; when the deviation coefficient of each steam generator is less than the deviation standard value, entering the normal mode; wherein the normal mode comprises: calculating the reactor power according to the first main feed water flow of each steam generator, and setting the full power reference value of the reactor to the first set value. The present application can reduce the measurement uncertainty of the reactor power, improve the maximum settable power of the reactor and the economy of the nuclear power plant.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of reactor power detection, and particularly relates to a reactor power determination method and system. BACKGROUND

[0002] The reactor power is an important monitoring parameter during the normal operation of a nuclear power plant. Since the reactor power cannot be directly and accurately measured, the reactor power can only be calculated by measuring the power of the secondary loop according to the energy balance principle of the primary loop and the secondary loop by means of a test instrument system (KME system for short). In the process of calculating the reactor power, the main feed water flow is the dominant factor affecting the measurement uncertainty of the reactor power, and the proportion can even reach 80%.

[0003] In the related art, the nuclear power plant generally measures the main feed water flow by using a differential pressure flowmeter. However, the differential pressure flowmeter has problems such as large main feed water pressure loss, large maintenance workload, narrow effective flow range (ratio of maximum flow to minimum flow), and easy fouling on the orifice plate surface or long-time scouring to cause a decrease in measurement accuracy. Therefore, the assumed value of the measurement uncertainty of the reactor power is relatively high (may be as high as 2%), which can sufficiently envelope the actual range of the measurement uncertainty. Based on the assumption of the measurement uncertainty of 2%, the power level considered in the safety analysis of the nuclear power plant is 102% of the design full power. However, in actual operation, the reactor power cannot exceed the full power, that is, the maximum set power of the reactor cannot exceed 100%, which leads to the fact that the operation power cannot be utilized to the maximum extent. For a million-kilowatt unit, even if the power generation amount of 1% is lost, the economic efficiency of the nuclear power plant is also negatively affected. SUMMARY

[0004] The present application aims to solve the technical problem of providing a reactor power determination method and system.

[0005] The technical solution adopted by the present application to solve the technical problem is that a reactor power determination method is constructed, comprising:

[0006] Periodically acquiring first main feed water flows and second main feed water flows respectively corresponding to a plurality of steam generators; wherein the first main feed water flow and the second main feed water flow are respectively the flows output by a preset flowmeter and a differential pressure flowmeter when measuring the flow of the corresponding steam generator, and the measurement uncertainty of the preset flowmeter is smaller than the measurement uncertainty of the differential pressure flowmeter;

[0007] Calculating a deviation coefficient corresponding to each steam generator according to the latest acquired first main feed water flow and second main feed water flow;

[0008] Determining whether the deviation coefficients of the steam generators are all smaller than a set deviation standard value;

[0009] When the deviation coefficients of all the steam generators are less than the deviation standard value, entering a normal mode; wherein the normal mode comprises: calculating the reactor power according to the first main feedwater flow of each steam generator, and setting a full power reference value of the reactor as a first set value.

[0010] Preferably, the reactor power determination method further comprises:

[0011] When there is at least one steam generator whose deviation coefficient is not less than the deviation standard value, entering a fault mode; wherein the fault mode comprises: calculating the reactor power according to the second main feedwater flow of each steam generator, and setting the full power reference value as the first set value, and the duration that the full power reference value is set as the first set value is not greater than a first set time.

[0012] Preferably, the fault mode further comprises:

[0013] judging whether the duration that the full power reference value is set as the first set value is greater than a first set time;

[0014] When the duration is not greater than the first set time, if the deviation coefficients of all the steam generators calculated according to the latest obtained first main feedwater flow and second main feedwater flow are less than the deviation standard value, entering the normal mode;

[0015] When the duration is greater than the first set time, prohibiting switching from the fault mode to the normal mode, and setting the full power reference value of the reactor as a second set value; wherein the first set value is greater than the second set value.

[0016] Preferably, the reactor power determination method further comprises:

[0017] calculating a reactor power measurement uncertainty according to the maximum measurement uncertainty of the preset flow meter, so as to determine the first set value according to the reactor power measurement uncertainty.

[0018] Preferably, the expression of the reactor power measurement uncertainty is:

[0019]

[0020] wherein U(W R ) represents the reactor power measurement uncertainty, W R represents reactor power, U(W SG1 ) represents the measurement uncertainty of the first steam generator, W SG1 represents the thermal power of the first steam generator, U(W SG2) represents the measurement uncertainty of the second steam generator, W SG2 represents the thermal power of the second steam generator, U(W SG3 ) represents the measurement uncertainty of the third steam generator, W SG3 represents the thermal power of the third steam generator, U(W ΔPR ) represents the measurement uncertainty of the other heat source input item except the core, W ΔPR represents the thermal power of the other heat source input item.

[0021] Preferably, the first set time ranges from 2 to 3 days.

[0022] Preferably, the first set value is 101.7% and / or the second set value is 100%.

[0023] Preferably, the expression of the deviation coefficient is:

[0024]

[0025] wherein k Q represents the deviation coefficient, Q CSB represents the first main feedwater flow, Q KBF represents the second main feedwater flow.

[0026] Preferably, the set range of the deviation standard value is 0.4% to 0.7%.

[0027] The present application also provides a reactor power determination system, comprising:

[0028] a plurality of preset flowmeters for measuring the main feedwater flow of the plurality of steam generators;

[0029] a plurality of differential pressure flowmeters for measuring the main feedwater flow of the plurality of steam generators; and

[0030] a control module comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the reactor power determination method as described above when executing the computer program.

[0031] The technical scheme of the present application calculates the deviation coefficient corresponding to each steam generator by periodically obtaining the first main feedwater flow and the second main feedwater flow corresponding to each steam generator, and then enters the normal mode when the deviation coefficient of each steam generator is less than the set deviation standard value, so as to calculate the reactor power according to the first main feedwater flow of each steam generator and set the full power reference value of the reactor to the first set value, so that the maximum settable power of the reactor can be set to a larger value, which helps to improve the economy of the nuclear power plant. Attached Figure Description

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0033] Figure 1 This is a flowchart of the reactor power determination method in some embodiments of the present invention;

[0034] Figure 2 This is a waveform diagram of reactor power in some embodiments of the present invention;

[0035] Figure 3 This is a structural block diagram of a reactor power determination system in some embodiments of the present invention. Detailed Implementation

[0036] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0037] It should be noted that the flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0038] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0039] Figure 1 This is a flowchart illustrating a reactor power determination method in some embodiments of the present invention. This reactor power determination method improves the measurement accuracy of the main feedwater flow rate and reduces the measurement uncertainty of the reactor power, thereby increasing the maximum settable power of the reactor and contributing to improved economics of nuclear power plants. Please refer to... Figure 1 The method may include steps S10, S20, S30 and S40.

[0040] The step S10 comprises: periodically acquiring the first main feedwater flow and the second main feedwater flow corresponding to each of the plurality of steam generators; wherein the first and second main feedwater flows are respectively the flow output by the preset flowmeter and the differential pressure flowmeter when measuring the flow of the corresponding steam generator, and the measurement uncertainty of the preset flowmeter is less than that of the differential pressure flowmeter. In some nuclear power plants, three steam generators are usually provided to realize heat exchange between the primary and secondary loops, and at least one preset flowmeter and at least one differential pressure flowmeter are respectively arranged at the feedwater inlet of each steam generator to measure the main feedwater flow of the corresponding steam generator. For the same steam generator, if multiple preset flowmeters and differential pressure flowmeters are provided to measure the main feedwater flow, the average of the measurement values of the preset flowmeters can be taken as the first main feedwater flow, and the average of the measurement values of the differential pressure flowmeters can be taken as the second main feedwater flow. It can be understood that the embodiment of configuring multiple flowmeters according to the redundancy principle helps to improve the reliability of the method.

[0041] In addition, the differential pressure flowmeter is an existing flowmeter for measuring the main feedwater flow, and the preset flowmeter is a newly added flowmeter. The preset flowmeter can be an ultrasonic flowmeter of model AH-UFM-1182, and the maximum measurement uncertainty of the ultrasonic flowmeter is not more than 0.3%. Of course, the preset flowmeter can also be other forms of flowmeters, as long as the measurement uncertainty is lower than that of the existing differential pressure flowmeter. The maximum measurement uncertainty of the existing differential pressure flowmeter is generally between 0.7% and 0.8%.

[0042] Further, in order to ensure that the measurement environments of the two flowmeters are consistent, the accuracy of the preset flowmeter is preferably set at a position close to or the same as the differential pressure flowmeter that measures the same target (i.e., measures the main feedwater flow of the same steam generator), so as to avoid measurement errors due to different measurement environments, which can adversely affect the subsequent steps and help to improve the reliability of the application.

[0043] In some embodiments, the reactor power determination method can further comprise: acquiring a period setting instruction to set the acquisition period of the first main feedwater flow and the second main feedwater flow according to the period setting instruction. In this embodiment, the user can input the period setting instruction through the human-computer interaction unit according to the demand, so as to realize the self-defined setting of the acquisition period.

[0044] Step S20 includes calculating the deviation coefficient corresponding to each steam generator according to the newly acquired first main feedwater flow and second main feedwater flow. In this step, after each time a new first main feedwater flow and second main feedwater flow are acquired, the latest deviation coefficient corresponding to each steam generator is calculated according to the newly acquired first main feedwater flow and second main feedwater flow, and step S30 is executed based on the latest calculated deviation coefficient.

[0045] In some embodiments, the deviation coefficient can be calculated by the following expression: wherein k Q represents the deviation coefficient, Q CSB represents the first main feedwater flow, Q KBF represents the second main feedwater flow.

[0046] Step S30 includes determining whether the deviation coefficient of each steam generator is less than a set deviation standard value. In this step, the user can input a setting instruction through the human-computer interaction unit to customize the deviation standard value. Generally, the deviation standard value can be determined by the measurement uncertainty of the pre-set flow meter and differential pressure flow meter. The smaller the deviation standard value is set, the more conservative the maximum settable power of the reactor is, which is more conducive to ensuring the safety of the nuclear power plant, but is not conducive to improving the economy of the nuclear power plant. Therefore, in order to maximize the economy of the nuclear power plant while ensuring safety, the setting range of the deviation standard value can be 0.4% to 0.7%.

[0047] Step S40 includes entering a normal mode when the deviation coefficient of each steam generator is less than the deviation standard value, wherein the normal mode includes calculating the reactor power according to the first main feedwater flow of each steam generator, and setting the full power reference value of the reactor to a first set value. In this step, based on the principle of conservatism, it must be ensured that the deviation coefficient corresponding to each steam generator is less than the deviation standard value before entering the normal mode. The first set value is greater than 100%, which is equivalent to setting the full power reference value of the reactor to a higher power, i.e., increasing the maximum settable power of the reactor, which is helpful to improve the economy of the nuclear power plant.

[0048] In some embodiments, the reactor power can be calculated by the following expression:

[0049]

[0050] wherein H vi represents the wet steam enthalpy value of the i-th steam generator, H ei represents the feedwater enthalpy value of the i-th steam generator, Q ei represents the main feedwater flow of the i-th steam generator, Hpi represents the enthalpy of blowdown of the i-th steam generator, Q pi represents the blowdown flow rate of the i-th steam generator, W ΔPR represents the heat power of the heat source other than the core; wherein, i = (1, 2, 3). In addition, H vi , H ei and W ΔPR can be obtained by the prior art, and will not be described here.

[0051] In some embodiments, the reactor power determination method can further include step S50.

[0052] Step S50 includes: when the deviation coefficient of at least one steam generator is not less than the deviation standard value, entering a fault mode; wherein the fault mode includes: calculating the reactor power according to the second main feedwater flow rate of each steam generator, and setting the full power reference value to a first set value, and the duration for which the full power reference value is set to the first set value is not greater than a first set time. Since the existing differential pressure flowmeter is a pure mechanical component, the failure rate is lower than that of the preset flowmeter, and when the deviation coefficient of a certain steam generator is greater than the deviation standard value, it is presumed that the preset flowmeter has a failure, and the reactor power is influenced by the three steam generators, based on the principle of conservation, the fault mode is entered.

[0053] Considering that the measurement values of the preset flowmeter and the differential pressure flowmeter can be short-term non-reproducible fluctuations caused by external factors, and thus mis-entering the fault mode, in some embodiments, the fault mode can further include: judging whether the duration for which the full power reference value is set to the first set value is greater than the first set time; when the duration is not greater than the first set time, if the deviation coefficients of each steam generator calculated according to the latest obtained first main feedwater flow rate and second main feedwater flow rate are all less than the deviation standard value, entering a normal mode; when the duration is greater than the first set time, prohibiting switching from the fault mode to the normal mode, and setting the full power reference value of the reactor to a second set value; wherein the first set value is greater than the second set value. In this embodiment, when the duration for entering the fault mode does not exceed the first set time, as long as the latest calculated deviation coefficients of each steam generator are all less than the deviation standard value, it is considered that it is caused by the short-term fluctuation of the flowmeter, and thus the fault mode can be switched back to the normal mode; and when the deviation coefficient of at least one steam generator is not less than the deviation standard value at all times within the first set time, it is presumed that the preset flowmeter and the differential pressure flowmeter corresponding to the steam generator have a failure, and thus the switching from the fault mode to the normal mode is prohibited, and the user can manually switch back to the normal mode after confirming that the flowmeter failure is eliminated.

[0054] In some embodiments, the first set time can range from 2 to 3 days.

[0055] In some embodiments, the first set value can be determined by calculating a reactor power measurement uncertainty according to a maximum measurement uncertainty of a preset flow meter, and determining the first set value according to the reactor power measurement uncertainty.

[0056] In some embodiments, the reactor power measurement uncertainty can be calculated by the following expression: wherein U(W R ) represents the reactor power measurement uncertainty, W R represents the reactor power, U(W SG1 ) represents a first steam generator measurement uncertainty, W SG1 represents a first steam generator thermal power, U(W SG2 ) represents a second steam generator measurement uncertainty, W SG2 represents a second steam generator thermal power, U(W SG3 ) represents a third steam generator measurement uncertainty, W SG3 represents a third steam generator thermal power, U(W ΔPR ) represents a measurement uncertainty of other heat source input items other than the reactor core, W ΔPR represents a thermal power of the other heat source input items. In addition, U(W ΔPR ) and W ΔPR can be determined by existing technologies or taken as empirical values.

[0057] Further, the thermal power of the steam generator can be calculated by the following expression (the formula is applicable to each steam generator): W SG = (H v - H e ) Q e - (H v - H p ) Q p ; wherein W SG represents the thermal power of the steam generator, H v represents the wet steam enthalpy of the steam generator, H e represents the feedwater enthalpy of the steam generator, Q e represents the feedwater flow of the steam generator, H p represents the blowdown enthalpy of the steam generator, Q p represents the blowdown flow of the steam generator. In addition, the measurement uncertainty of each steam generator (including U(W SG1 ), U(W SG2 ), U(W SG3))The thermal power of the steam generator can be determined by using existing algorithm techniques, and no limitation is made herein.

[0058] Since the reactor power is calculated based on the measurement value of the differential pressure flowmeter, the second set value can use the existing set value, i.e., the second set value can be set to 100%. For the preset flowmeter, since the measurement uncertainty of the preset flowmeter is smaller than that of the differential pressure flowmeter, the reactor power measurement uncertainty is lower, and therefore the first set value can be set to a higher value, for example, the first set value is set to 101.7% in some embodiments. Please refer to Figure 2 , it should be noted that Figure 2 The failure mode (reactor power is calculated based on the measurement value of the differential pressure flowmeter) is that the amplitude of the reactor power change waveform is as high as 4% after the failure mode duration exceeds the first set time, and the maximum full power reference value of the reactor can only be set to 100% to ensure safety. In the normal mode (reactor power is calculated based on the measurement value of the preset flowmeter), the amplitude is only 0.6%, and therefore the maximum full power reference value of the reactor can be set to 101.7%.

[0059] It can be understood that by periodically obtaining the first main feed water flow and the second main feed water flow corresponding to each steam generator to calculate the deviation coefficient corresponding to each steam generator, and then entering the normal mode when the deviation coefficient of each steam generator is less than the set deviation standard value, the reactor power is calculated according to the first main feed water flow of each steam generator, and the maximum settable power of the reactor is set to a larger value, which helps to improve the economy of the nuclear power plant.

[0060] As Figure 3 shown, the present application also provides a reactor power determination system, comprising a plurality of preset flowmeters 1, a plurality of differential pressure flowmeters 2, and a control module 3.

[0061] The plurality of preset flowmeters 1 are used to measure the main feed water flow of the plurality of steam generators. At least one preset flowmeter 1 is arranged in each steam generator to measure the feed water inlet flow of the corresponding steam generator, thereby obtaining the corresponding first main feed water flow.

[0062] The plurality of differential pressure flowmeters 2 are used to measure the main feed water flow of the plurality of steam generators. At least one differential pressure flowmeter 2 is arranged in each steam generator to measure the feed water inlet flow of the corresponding steam generator, thereby obtaining the corresponding second main feed water flow.

[0063] The control module 3 comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the reactor power determination method provided by the embodiments of the application when executing the computer program.

[0064] The various embodiments are described in a progressive manner in the specification, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other. For the device disclosed by the embodiments, since it corresponds to the method disclosed by the embodiments, the description is relatively simple, and the relevant parts can be referred to the method part.

[0065] The skilled person can further realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be realized by electronic hardware, computer software or a combination of both. In order to clearly illustrate the interchangeability of hardware and software, the components and steps of the examples have been described in the above description in general terms. Whether the functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0066] The steps of the method or algorithm described in combination with the embodiments disclosed herein can be directly implemented by hardware, a software module executed by a processor, or a combination of both. The software module can be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0067] It can be understood that the above embodiments only express the preferred embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent of the present application. It should be noted that for those skilled in the art, the above technical features can be freely combined without departing from the concept of the present application, and several modifications and improvements can be made, which are all within the scope of protection of the present application. Therefore, any equivalent transformation and modification within the scope of the claims of the present application should be covered by the claims of the present application.

Claims

1. A method for determining reactor power, characterized in that, include: The first main feedwater flow rate and the second main feedwater flow rate corresponding to multiple steam generators are acquired periodically; wherein, the first and second main feedwater flow rates are the flow rates output by the preset flow meter and the differential pressure flow meter when measuring the flow rate of the corresponding steam generator, respectively, and the measurement uncertainty of the preset flow meter is less than the measurement uncertainty of the differential pressure flow meter. The deviation coefficients corresponding to each steam generator are calculated based on the latest obtained first and second main feedwater flow rates. Determine whether the deviation coefficient of each steam generator is less than the set deviation standard value; When the deviation coefficients of each steam generator are less than the deviation standard value, the system enters the normal mode; wherein, the normal mode includes: calculating the reactor power based on the first main feedwater flow rate of each steam generator, and setting the full power reference value of the reactor to a first set value.

2. The reactor power determination method according to claim 1, characterized in that, Also includes: When at least one of the steam generators has a deviation coefficient that is not less than the deviation standard value, a fault mode is entered; wherein, the fault mode includes: calculating the reactor power based on the second main feedwater flow rate of each of the steam generators, setting the full power reference value to the first set value, and the duration for which the full power reference value is set to the first set value is not greater than a first set time.

3. The reactor power determination method according to claim 2, characterized in that, The failure modes also include: Determine whether the duration for which the full power reference value is set to the first set value is greater than the first set time; When the duration is not greater than the first set time, if the deviation coefficients of each steam generator calculated based on the latest obtained first main feedwater flow rate and second main feedwater flow rate are both less than the deviation standard value, the normal mode is entered. When the duration exceeds the first set time, switching from the fault mode to the normal mode is prohibited, and the full power reference value of the reactor is set to a second set value; wherein the first set value is greater than the second set value.

4. The reactor power determination method according to claim 3, characterized in that, Also includes: The reactor power measurement uncertainty is calculated based on the maximum measurement uncertainty of the preset flow meter, and the first set value is determined based on the reactor power measurement uncertainty.

5. The reactor power determination method according to claim 3, characterized in that, The expression for the reactor power measurement uncertainty is: Among them, U(W R W represents the uncertainty in the reactor power measurement. R U(W) represents reactor power. SG1 W represents the measurement uncertainty of the first steam generator. SG1 U(W) represents the thermal power of the first steam generator. SG2 W represents the measurement uncertainty of the second steam generator. SG2 U(W) represents the thermal power of the second steam generator. SG3 W represents the measurement uncertainty of the third steam generator. SG3 U(W) represents the thermal power of the third steam generator. ΔPR W represents the measurement uncertainty of heat source inputs other than the reactor core. ΔPR This represents the thermal power of the other heat source input items.

6. The reactor power determination method according to any one of claims 2 to 5, characterized in that, The first set time range is 2 to 3 days.

7. The reactor power determination method according to any one of claims 2 to 5, characterized in that, The first setting is 101.7% and / or the second setting is 100%.

8. The reactor power determination method according to claim 1, characterized in that, The expression for the deviation coefficient is: Where, k Q Q represents the deviation coefficient. CSB Q represents the first main water supply flow rate. KBF This indicates the flow rate of the second main water supply.

9. The reactor power determination method according to claim 1, characterized in that, The standard deviation value is set within a range of 0.4% to 0.7%.

10. A reactor power determination system, characterized in that, include: Multiple preset flow meters are used to measure the main feedwater flow of multiple steam generators; Multiple differential pressure flow meters are used to measure the main feedwater flow of multiple steam generators; as well as A control module includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the reactor power determination method as described in any one of claims 1 to 8.

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