Method and apparatus for determining doppler temperature coefficient

Abstract

The disclosure provides a method and device for determining Doppler temperature coefficient, and relates to the technical field of nuclear power. The method comprises the following steps: controlling the moderator to change at a preset temperature change rate, the temperature of the fuel changes with the temperature change of the moderator, and the temperature of the fuel and the moderator changes synchronously at the temperature change rate until the temperature of the fuel and the moderator changes synchronously; during the temperature change process, the core reactivity data of the nuclear reactor is obtained, and linear fitting is performed to obtain a reactivity change curve; the reactivity difference between the core reactivity data at the initial control time of the temperature change and the reactivity change curve, and the temperature difference when the fuel and the moderator change synchronously are determined; and the ratio of the reactivity difference to the temperature difference is determined as the Doppler temperature coefficient of the fuel. The disclosure uses the temperature difference between the moderator and the fuel in the nuclear reactor and the reactivity difference of the core reactivity data to obtain the Doppler temperature coefficient of the fuel, without relying on theoretical values or empirical values, which is convenient to operate and has higher coefficient accuracy.

Description

Technical Field

[0001] This disclosure relates to the field of nuclear power technology, and in particular to a method and apparatus for determining the Doppler temperature coefficient. Background Technology

[0002] The change in reactor reactivity caused by a 1°C change in the moderator temperature coefficient is called the moderator temperature coefficient α. mod This parameter is crucial for reactor safety and must be negative during the design process. This means that an increase in moderator temperature introduces negative reactivity, leading to a decrease in reactor power and ensuring reactor self-stabilization. After fuel loading is complete, the moderator temperature coefficient needs to be measured. The common practice is to disrupt the thermal equilibrium of the primary and secondary loops before the nuclear pyroelectric point to alter the temperatures of the moderator and fuel. A reactivity meter is used to measure the change in reactivity during the temperature change process. The ratio of this change in reactivity to the change in temperature is the isothermal temperature coefficient (moderator temperature coefficient α). mod +Fuel Doppler temperature coefficient α dop Then, subtract the fuel Doppler temperature coefficient from the isothermal temperature coefficient to obtain the moderator temperature coefficient.

[0003] The change in reactor reactivity resulting from a 1°C change in fuel temperature is known as the fuel Doppler temperature coefficient. Since fuel temperature cannot be directly measured, current fuel Doppler temperature coefficients are theoretical or empirical values ​​calculated by software. The accuracy of this value directly affects the measured value of the moderator temperature coefficient, and consequently, reactor safety. Furthermore, inaccuracies in the fuel Doppler temperature coefficient can lead to inaccuracies in the physics-thermal coupling during nuclear design program development, thus reducing the accuracy of program calculations. Summary of the Invention

[0004] This disclosure aims to at least partially address one of the technical problems in the related art.

[0005] Therefore, the first aspect of this disclosure provides a method for determining the Doppler temperature coefficient, the method being applied to a nuclear reactor, the nuclear reactor comprising fuel and a moderator, the method comprising the following steps:

[0006] The temperature of the moderator is controlled to change at a preset temperature change rate, and the temperature of the fuel changes with the temperature of the moderator. When the temperature change time of the moderator exceeds a first time value, the temperature of the fuel and the temperature of the moderator change synchronously with the temperature change rate.

[0007] During the temperature change of the moderator, the core reactivity data of the nuclear reactor is acquired;

[0008] Linear fitting was performed on the core reactivity data to obtain the reactivity change curve;

[0009] Determine the reactivity difference between the core reactivity data and the reactivity change curve at the initial control moment of temperature change;

[0010] Based on the heat absorbed per unit length of the fuel according to the rate of temperature change and the heat transfer equation, determine the temperature difference when the temperature of the fuel and the temperature of the moderator change synchronously with the rate of temperature change.

[0011] The ratio of the reactivity difference to the temperature difference is determined as the Doppler temperature coefficient of the fuel.

[0012] In some embodiments of this disclosure, the heat absorbed by the fuel per unit length according to the rate of temperature change is obtained by the following formula:

[0013]

[0014] in, The heat absorbed by the fuel per unit length according to the rate of temperature change. For the specific heat capacity of fuel, fuel mass per unit length The rate of temperature change is denoted as .

[0015] In some embodiments of this disclosure, the heat transfer equation is expressed as follows:

[0016]

[0017] in, The heat absorbed by the fuel per unit length according to the rate of temperature change. The heat transfer coefficient is... For heat exchange area, The temperature difference is mentioned.

[0018] In some embodiments of this disclosure, the nuclear reactor is in a hot standby state and has not reached its nuclear pyroelectric point.

[0019] A second aspect of this disclosure provides an apparatus for determining the Doppler temperature coefficient, the apparatus being applied to a nuclear reactor comprising fuel and a moderator, the apparatus comprising:

[0020] A temperature control module is used to control the temperature of the moderator to change at a preset temperature change rate. The temperature of the fuel changes with the temperature of the moderator. When the temperature change time of the moderator exceeds a first time value, the temperature of the fuel and the temperature of the moderator change synchronously with the temperature change rate.

[0021] The first acquisition module is used to acquire the core reactivity data of the nuclear reactor during the temperature change of the moderator;

[0022] The second acquisition module is used to perform linear fitting on the core reactivity data to obtain a reactivity change curve;

[0023] The third acquisition module is used to determine the reactivity difference between the core reactivity data and the reactivity change curve at the initial control moment of the temperature change.

[0024] The fourth acquisition module is used to determine the temperature difference between the temperature of the fuel and the temperature of the moderator when they change synchronously with the temperature change rate, based on the heat absorbed by the fuel per unit length according to the temperature change rate and the heat transfer equation.

[0025] The determination module is used to determine the ratio of the reactivity difference to the temperature difference as the Doppler temperature coefficient of the fuel.

[0026] In some embodiments of this disclosure, the fourth acquisition module is further configured to obtain the heat absorbed by the fuel per unit length according to the rate of temperature change using the following formula:

[0027]

[0028] in, The heat absorbed by the fuel per unit length according to the rate of temperature change. For the specific heat capacity of fuel, fuel mass per unit length The rate of temperature change is denoted as .

[0029] In some embodiments of this disclosure, the heat transfer equation is expressed as follows:

[0030]

[0031] in, The heat absorbed by the fuel per unit length according to the rate of temperature change. The heat transfer coefficient is... For heat exchange area, The temperature difference is mentioned.

[0032] In some embodiments of this disclosure, the nuclear reactor is in a hot standby state and has not reached its nuclear pyroelectric point.

[0033] A third aspect of this disclosure provides an electronic device, including: a processor, and a memory communicatively connected to the processor;

[0034] The memory stores computer-executed instructions;

[0035] The processor executes computer execution instructions stored in the memory to implement the method described in the first aspect above.

[0036] A fourth aspect of this disclosure provides a computer-readable storage medium, characterized in that the computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the method described in the first aspect above.

[0037] The method for determining the Doppler temperature coefficient disclosed herein utilizes the temperature difference between the moderator and fuel in a nuclear reactor, as well as the reactivity difference in core reactivity data, to obtain the fuel Doppler temperature coefficient. This method eliminates the need to rely on theoretical or empirical values, offering greater operational convenience and higher accuracy. It indirectly improves the accuracy of the moderator temperature coefficient, ensuring nuclear reactor safety, and can also, to some extent, avoid the reduction in program calculation accuracy caused by inaccurate physics-thermal coupling during nuclear design program development.

[0038] Additional aspects and advantages of this disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this disclosure. Attached Figure Description

[0039] The above and / or additional aspects and advantages of this disclosure will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, in which:

[0040] Figure 1 A schematic flowchart illustrating a method for determining the Doppler temperature coefficient provided in an embodiment of this disclosure;

[0041] Figure 2 This is a schematic diagram illustrating a method for controlling the temperature of fuel and the temperature of a moderator to change synchronously with a rate of temperature change, as provided in an embodiment of this disclosure.

[0042] Figure 3 This is a schematic diagram illustrating the acquisition of core reactivity data during a temperature change process of a moderator, as provided in an embodiment of this disclosure.

[0043] Figure 4 This is a schematic diagram of a Doppler temperature coefficient determination device provided in an embodiment of the present disclosure. Detailed Implementation

[0044] Embodiments of this disclosure are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this disclosure, and should not be construed as limiting this disclosure.

[0045] Specifically, the method and apparatus for determining the Doppler temperature coefficient according to embodiments of this disclosure are described below with reference to the accompanying drawings. This disclosure relates to the field of nuclear power technology, and more particularly to the field of nuclear power plant and research reactor technology.

[0046] Figure 1 This is a schematic flowchart illustrating a method for determining the Doppler temperature coefficient provided in an embodiment of this disclosure. It should be noted that this method is applied to a nuclear reactor, which includes fuel and a moderator. Figure 1 As shown, the method for determining the Doppler temperature coefficient may include the following steps:

[0047] Step 101: Control the temperature of the moderator to change at a preset temperature change rate. The temperature of the fuel changes with the temperature of the moderator. When the temperature change time of the moderator exceeds a first time value, the temperature of the fuel and the temperature of the moderator change synchronously with the temperature change rate.

[0048] It should be noted that in some embodiments of this disclosure, the nuclear reactor is in a hot standby state and has not reached the nuclear heating point, that is, the embodiments of this disclosure are implemented before the reactor nuclear heating, and the fuel Doppler temperature coefficient is measured.

[0049] In one implementation, at the initial control time t1 of the temperature change, the initial temperature of the moderator and the initial temperature of the fuel are the same, T1, and the core reactivity is ρ1. The temperature of the moderator in the primary loop is maintained at a constant rate of temperature change by disrupting the thermal equilibrium between the primary and secondary loops. With uniform temperature variation, the moderator transfers heat to the fuel, causing the fuel temperature to change with the temperature of the moderator. Figure 2 This is a schematic diagram illustrating a method for controlling the temperature of fuel and the temperature of a moderator to change synchronously at a rate of temperature change, as provided in an embodiment of this disclosure. Figure 2 Taking uniform heating as an example (the cooling analysis process is similar), from Figure 2 It can be seen that the fuel temperature does not change at a uniform rate in the early stage. Instead, after the temperature difference with the moderator reaches a certain level or the time for temperature change exceeds the first time value, the fuel and the moderator maintain the same rate of temperature change. Synchronous changes.

[0050] Step 102: Acquire core reactivity data of the nuclear reactor during the temperature change of the moderator.

[0051] In some embodiments of this disclosure, the control time for the fuel temperature and the moderator temperature needs to be sufficiently long, such as 15 minutes or more (this control time is merely exemplary and is not intended to limit this solution; other control times are also possible and are not limited thereto). During the temperature change of the moderator, core reactivity data of the nuclear reactor is acquired over a preset time period.

[0052] Figure 3This is a schematic diagram illustrating the acquisition of core reactivity data during the temperature change process of a moderator, as provided in an embodiment of this disclosure.

[0053] Step 103: Perform linear fitting on the core reactivity data to obtain the reactivity change curve.

[0054] Linear fitting was performed on the core reactivity data to obtain the reactivity change curve:

[0055]

[0056] in, For core reactivity data, This refers to the control time for temperature changes.

[0057] Step 104: Determine the reactivity difference between the core reactivity data and the reactivity change curve at the initial control moment of temperature change.

[0058] Determine the fitted core reactivity data corresponding to the initial control time t1 of the temperature change in the reactivity change curve. Determine the actual core reactivity data obtained at the initial control time t1. This allows for the determination of the fitted core reactivity data. With core reactivity data The difference in reactivity between them:

[0059]

[0060] Step 105: Based on the heat absorbed per unit length of fuel according to the rate of temperature change and the heat transfer equation, determine the temperature difference when the temperature of the fuel and the temperature of the moderator change synchronously with the rate of temperature change.

[0061] The amount of heat absorbed per unit length of fuel according to the rate of temperature change is obtained by the following formula:

[0062]

[0063] in, This refers to the amount of heat absorbed per unit length of fuel according to the rate of temperature change. For the specific heat capacity of fuel, fuel mass per unit length The rate of temperature change.

[0064] Based on the heat absorbed per unit length of fuel according to the rate of temperature change obtained from the above formula, the temperature difference when the fuel temperature and the moderator temperature change synchronously according to the rate of temperature change can be determined using the heat transfer equation. The heat transfer equation can be expressed as follows:

[0065]

[0066] in, This refers to the amount of heat absorbed per unit length of fuel according to the rate of temperature change. The heat transfer coefficient can be calculated based on a heat transfer model. The heat exchange area can be calculated using the geometry per unit length. This refers to the temperature difference.

[0067] Step 106: The ratio of the reactivity difference to the temperature difference is determined as the Doppler temperature coefficient of the fuel.

[0068] Because of the heat conduction between the moderator and the fuel, a temperature difference exists when the fuel and moderator change synchronously. This leads to a discrepancy between the actual core reactivity data and the fitted core reactivity data at the initial control time. The difference in reactivity. Based on this principle, the fuel Doppler temperature coefficient can be derived. .

[0069] In some embodiments of this disclosure, the fuel Doppler temperature coefficient can be accurately obtained by utilizing the temperature difference between the moderator and the fuel in the nuclear reactor and the reactivity difference of the core reactivity data, thereby improving the accuracy of the moderator temperature coefficient.

[0070] By implementing the embodiments of this disclosure, the fuel Doppler temperature coefficient is obtained using the temperature difference between the moderator and fuel in a nuclear reactor and the reactivity difference of the core reactivity data. This eliminates the need to rely on theoretical or empirical values, making the operation convenient, easy to promote, and with higher accuracy. It indirectly improves the accuracy of the moderator temperature coefficient, ensuring the safety of the nuclear reactor, and can also, to some extent, avoid the reduction in program calculation accuracy caused by inaccurate physics-thermal coupling during nuclear design program development.

[0071] Figure 4 This is a schematic diagram of a Doppler temperature coefficient determination device provided in an embodiment of this disclosure. Figure 4 As shown, the device may include: a temperature control module 401, a first acquisition module 402, a second acquisition module 403, a third acquisition module 404, a fourth acquisition module 405, and a determination module 406.

[0072] The temperature control module 401 is used to control the temperature of the moderator to change at a preset temperature change rate. The temperature of the fuel changes with the temperature of the moderator. When the temperature change time of the moderator exceeds a first time value, the temperature of the fuel and the temperature of the moderator change synchronously with the temperature change rate.

[0073] The first acquisition module 402 is used to acquire core reactivity data of the nuclear reactor during the temperature change of the moderator.

[0074] The second acquisition module 403 is used to perform linear fitting on the core reactivity data to obtain the reactivity change curve.

[0075] The third acquisition module 404 is used to determine the reactivity difference between the core reactivity data and the reactivity change curve at the initial control moment of temperature change.

[0076] The fourth acquisition module 405 is used to determine the temperature difference between the fuel temperature and the moderator temperature when they change synchronously with the rate of temperature change, based on the heat absorbed by the fuel per unit length according to the rate of temperature change and the heat transfer equation.

[0077] In some embodiments of this disclosure, the fourth acquisition module 405 is further configured to obtain the heat absorbed per unit length of fuel according to the rate of temperature change using the following formula:

[0078]

[0079] in, This refers to the amount of heat absorbed per unit length of fuel according to the rate of temperature change. For the specific heat capacity of fuel, fuel mass per unit length The rate of temperature change.

[0080] In some embodiments of this disclosure, the heat transfer equations are expressed as follows:

[0081]

[0082] in, This refers to the amount of heat absorbed per unit length of fuel according to the rate of temperature change. The heat transfer coefficient is... For heat exchange area, This refers to the temperature difference.

[0083] The determination module 406 is used to determine the ratio of the reactivity difference to the temperature difference as the Doppler temperature coefficient of the fuel.

[0084] In some embodiments of this disclosure, the nuclear reactor is in a hot standby state and has not reached its nuclear pyroelectric point.

[0085] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0086] To implement the above embodiments, this disclosure also proposes an electronic device, including: a processor and a memory communicatively connected to the processor; the memory stores computer execution instructions; the processor executes the computer execution instructions stored in the memory to implement the method provided in the foregoing embodiments.

[0087] To implement the above embodiments, this disclosure also proposes a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the methods provided in the foregoing embodiments.

[0088] To implement the above embodiments, this disclosure also proposes a computer program product, including a computer program that, when executed by a processor, implements the methods provided in the foregoing embodiments.

[0089] In the foregoing descriptions of the embodiments, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0090] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0091] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing custom logic functions or processes, and the scope of preferred embodiments of this disclosure includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of this disclosure pertain.

[0092] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0093] It should be understood that various parts of this disclosure can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0094] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0095] Furthermore, the functional units in the various embodiments of this disclosure can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0096] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of the present disclosure have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present disclosure. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present disclosure.

Claims

1. A method for determining the Doppler temperature coefficient, said method being applied to a nuclear reactor, said nuclear reactor comprising fuel and moderator, characterized in that, The method includes the following steps: The temperature of the moderator is controlled to change at a preset temperature change rate, and the temperature of the fuel changes with the temperature of the moderator. When the temperature change time of the moderator exceeds a first time value, the temperature of the fuel and the temperature of the moderator change synchronously with the temperature change rate. During the temperature change of the moderator, the core reactivity data of the nuclear reactor is acquired; Linear fitting was performed on the core reactivity data to obtain the reactivity change curve; Determine the reactivity difference between the core reactivity data and the reactivity change curve at the initial control moment of temperature change; Based on the heat absorbed per unit length of the fuel according to the rate of temperature change and the heat transfer equation, determine the temperature difference when the temperature of the fuel and the temperature of the moderator change synchronously with the rate of temperature change. The ratio of the reactivity difference to the temperature difference is determined as the Doppler temperature coefficient of the fuel.

2. The method according to claim 1, characterized in that, The amount of heat absorbed per unit length of fuel according to the rate of temperature change is obtained by the following formula: Φ=C*M*△t Wherein, Φ is the heat absorbed by the fuel per unit length according to the rate of temperature change, C is the specific heat capacity of the fuel, M is the mass of the fuel per unit length, and Δt is the rate of temperature change.

3. The method according to claim 1 or 2, characterized in that, The heat transfer equation is expressed as follows: Φ=K*A*△T1 Wherein, Φ is the heat absorbed by the fuel per unit length according to the rate of temperature change, K is the heat transfer coefficient, A is the heat exchange area, and ΔT1 is the temperature difference.

4. The method according to claim 1, characterized in that, The nuclear reactor is in hot standby mode and has not reached its nuclear pyroelectric point.

5. A device for determining the Doppler temperature coefficient, said device being applied to a nuclear reactor, said nuclear reactor comprising fuel and moderator, characterized in that, The device includes: A temperature control module is used to control the temperature of the moderator to change at a preset temperature change rate. The temperature of the fuel changes with the temperature of the moderator. When the temperature change time of the moderator exceeds a first time value, the temperature of the fuel and the temperature of the moderator change synchronously with the temperature change rate. The first acquisition module is used to acquire the core reactivity data of the nuclear reactor during the temperature change of the moderator; The second acquisition module is used to perform linear fitting on the core reactivity data to obtain a reactivity change curve; The third acquisition module is used to determine the reactivity difference between the core reactivity data and the reactivity change curve at the initial control moment of the temperature change. The fourth acquisition module is used to determine the temperature difference between the temperature of the fuel and the temperature of the moderator when they change synchronously with the temperature change rate, based on the heat absorbed by the fuel per unit length according to the temperature change rate and the heat transfer equation. The determination module is used to determine the ratio of the reactivity difference to the temperature difference as the Doppler temperature coefficient of the fuel.

6. The apparatus according to claim 5, characterized in that, The fourth acquisition module is further configured to obtain the heat absorbed by the fuel per unit length according to the rate of temperature change using the following formula: Φ=C*M*△t Wherein, Φ is the heat absorbed by the fuel per unit length according to the rate of temperature change, C is the specific heat capacity of the fuel, M is the mass of the fuel per unit length, and Δt is the rate of temperature change.

7. The apparatus according to claim 5 or 6, characterized in that, The heat transfer equation is expressed as follows: Φ=K*A*△T1 Wherein, Φ is the heat absorbed by the fuel per unit length according to the rate of temperature change, K is the heat transfer coefficient, A is the heat exchange area, and ΔT1 is the temperature difference.

8. The apparatus according to claim 5, characterized in that, The nuclear reactor is in hot standby mode and has not reached its nuclear pyroelectric point.

9. An electronic device, characterized in that, include: A processor, and a memory communicatively connected to the processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory to implement the method as described in any one of claims 1-4.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the method as described in any one of claims 1-4.

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