Method for determining reactor core flow of pool type sodium-cooled fast reactor

Abstract

The embodiment of the invention relates to the technical field of reactor thermal hydraulic power, in particular to a method for determining the reactor core flow of a pool type sodium-cooled fast reactor, which is used for determining the reactor core flow of the pool type sodium-cooled fast reactor under an asymmetric working condition, and comprises the following steps: when the pool type sodium-cooled fast reactor is under a symmetric working condition, establishing an analysis model of the pool type sodium-cooled fast reactor; determining the calculated flow of the reactor core according to the analysis model of the pool type sodium-cooled fast reactor; the actual flow of the reactor core is determined in a measurement mode; comparing the calculated flow of the reactor core with the actual flow of the reactor core; according to a comparison result, correcting an analysis model of the pool type sodium-cooled fast reactor; and when the pool type sodium-cooled fast reactor is in an asymmetric working condition, determining the flow of the reactor core by using the corrected analysis model of the pool type sodium-cooled fast reactor. According to the method provided by the embodiment of the invention, the reactor core flow of the pool type sodium-cooled fast reactor under the symmetric working condition and the asymmetric working condition can be ensured to be computable, so that the influence of the reactor core flow on the safety of the reactor core is ensured to be known.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of reactor thermal hydraulic technology, and in particular to a method for determining the core flow rate of a pool-type sodium-cooled fast reactor. Background Art

[0002] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0003] The primary cooling system of a pool-type sodium-cooled fast reactor can include two or more parallel loops, each of which is arranged in the main container of the pool-type sodium-cooled fast reactor to form an integrated pool-type structure. The coolant of the primary cooling system is usually liquid metallic sodium. The process of the main cooling flow channel for cooling the core in each loop is as follows: the sodium pump draws sodium from the cold sodium pool, and sends the sodium to the grid header through the primary pressure pipeline, and then flows out of the core into the hot sodium pool after cooling the fuel assembly; the hot sodium flows downward from the upper inlet of the intermediate heat exchanger through the tube room and flows into the cold sodium pool from the lower outlet.

[0004] During the cooling process, it is very important to determine the cooling effect of the primary circuit by measuring the coolant flow rate. However, due to the structural characteristics of the primary circuit of the pool-type sodium-cooled fast reactor, it is currently impossible to set a measuring device in the primary circuit to directly measure the core flow rate or the primary circuit flow rate. Summary of the invention

[0005] A brief overview of the present application is provided below in order to provide a basic understanding of certain aspects of the present application. It should be understood that this overview is not an exhaustive overview of the present application. It is not intended to identify the key or important parts of the present application, nor is it intended to limit the scope of the present application. Its purpose is merely to present certain concepts in a simplified form as a prelude to a more detailed description discussed later.

[0006] In a first aspect, an embodiment of the present application provides a method for determining the core flow rate of a pool-type sodium-cooled fast reactor, the method being used to determine the core flow rate of a pool-type sodium-cooled fast reactor under an asymmetric operating condition, and comprising the following steps: S1: establishing an analysis model of a pool-type sodium-cooled fast reactor when the pool-type sodium-cooled fast reactor is under a symmetric operating condition; S2: determining a calculated flow rate of the core based on the analysis model of the pool-type sodium-cooled fast reactor; S3: determining an actual flow rate of the core by measurement; S4: comparing the calculated flow rate of the core determined in step S2 with the actual flow rate of the core determined in step S3; S5: correcting the analysis model of the pool-type sodium-cooled fast reactor based on the comparison result; S17: determining the core flow rate using the corrected analysis model of the pool-type sodium-cooled fast reactor determined in step S5 when the pool-type sodium-cooled fast reactor is under an asymmetric operating condition.

[0007] In the second aspect, an embodiment of the present application also provides a method for determining the core flow rate of a pool-type sodium-cooled fast reactor, the method is used to determine the core flow rate of a pool-type sodium-cooled fast reactor under an asymmetric operating condition, and comprises the following steps: establishing a first model and a second model when the pool-type sodium-cooled fast reactor is under a symmetric operating condition, the core flow rate can be determined by the first model, and the first model and the second model are verified under the symmetric operating condition; the first model and the second model are corrected according to the verification results; when the pool-type sodium-cooled fast reactor is under an asymmetric operating condition, the core flow rate is determined using the first model; and the determined core flow rate under the asymmetric operating condition is verified by the second model to determine the accuracy of the core flow rate.

[0008] The method provided in the embodiment of the present application establishes an analysis model of a pool-type sodium-cooled fast reactor when the pool-type sodium-cooled fast reactor is in a symmetrical operating condition, and then corrects the analysis model based on the comparison result between the calculated flow rate and the actual flow rate of the core, and uses the corrected analysis model to determine the flow rate of the core when the pool-type sodium-cooled fast reactor is in an asymmetric operating condition. This is conducive to ensuring that the core flow rate of the pool-type sodium-cooled fast reactor under both symmetrical and asymmetric conditions is calculable and the calculation results are relatively reliable; it is also conducive to ensuring that the influence of the core flow rate on the safety of the core is knowable.

[0009] These and other advantages of the present application will become more apparent through the following detailed description of the preferred embodiments of the present application in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to further illustrate the above and other advantages and features of the present application, the specific embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. The accompanying drawings together with the following detailed description are included in this specification and form a part of this specification. Elements with the same function and structure are represented by the same reference numerals. It should be understood that these drawings only describe typical examples of the present application and should not be regarded as limiting the scope of the present application.

[0011] Figure 1 It is a flow chart of a method for determining the core flow rate of a pool-type sodium-cooled fast reactor provided according to an embodiment of the present application.

[0012] It should be noted that the drawings are not necessarily drawn to scale, but are merely shown in a schematic manner that does not affect the reader's understanding. DETAILED DESCRIPTION

[0013] Exemplary embodiments of the present application will be described below in conjunction with the accompanying drawings. For the sake of clarity and conciseness, not all features of the actual implementation are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the process of developing any such actual implementation in order to achieve the developer's specific goals, such as meeting those constraints related to the system and business, and these constraints may vary from implementation to implementation. In addition, it should be understood that although the development work may be very complex and time-consuming, it is only a routine task for those skilled in the art who benefit from the content of this application.

[0014] It is also necessary to explain here that, in order to avoid obscuring the present application due to unnecessary details, only the device structure and / or processing steps closely related to the scheme according to the present application are shown in the accompanying drawings, while other details that are not very relevant to the present application are omitted.

[0015] The disclosure below provides a plurality of different embodiments or examples to implement the present application. In order to simplify the disclosure of the present application, the parts and methods of specific examples are described below. Of course, they are merely examples, and the purpose is not to limit the present application. In the description of the embodiments of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically limited.

[0016] In the related art, when determining the core flow rate of a pool-type sodium-cooled fast reactor, for a symmetrical working condition where the pressure heads of the main pumps in the primary circuit are equal, the core flow rate can be calculated by the measured value of the flow meter of the bypass flow channel of the main pump. However, for an asymmetric working condition where the pressure heads of the main pumps in the primary circuit are unequal, since two or more loops are retained in the primary cooling system of the primary circuit, the core flow rate cannot be calculated by the measured value of the flow meter of the bypass flow channel of the main pump. Currently, there is no method for measuring the core flow rate of a pool-type sodium-cooled fast reactor under the asymmetric working condition of the primary circuit flow rate.

[0017] In view of the above problems, an embodiment of the present application provides a method for determining the core flow rate of a pool-type sodium-cooled fast reactor. The method can be used to determine the core flow rate of a pool-type sodium-cooled fast reactor under asymmetric conditions, such as Figure 1 As shown, the method may at least include the following steps.

[0018] S1: Under the symmetrical operating condition of the pool-type sodium-cooled fast reactor, an analytical model of the pool-type sodium-cooled fast reactor is established.

[0019] S2: Determine the calculated flow rate of the core based on the analytical model of the pool-type sodium-cooled fast reactor.

[0020] S3: Determine the actual flow rate of the core by measurement.

[0021] S4: Compare the calculated flow rate of the core determined in step S2 with the actual flow rate of the core determined in step S3.

[0022] S5: Based on the comparison results, the analysis model of the pool-type sodium-cooled fast reactor is modified.

[0023] S17: When the pool-type sodium-cooled fast reactor is in an asymmetric operating condition, the flow rate of the core is determined using the revised analytical model of the pool-type sodium-cooled fast reactor determined in step S5.

[0024] The method provided in the embodiment of the present application establishes an analysis model of a pool-type sodium-cooled fast reactor when the pool-type sodium-cooled fast reactor is in a symmetrical operating condition, and then corrects the analysis model based on the comparison result between the calculated flow rate and the actual flow rate of the core, and uses the corrected analysis model to determine the flow rate of the core when the pool-type sodium-cooled fast reactor is in an asymmetric operating condition. This is conducive to ensuring that the core flow rate of the pool-type sodium-cooled fast reactor under both symmetrical and asymmetric conditions is calculable and the calculation results are relatively reliable; it is also conducive to ensuring that the influence of the core flow rate on the safety of the core is knowable.

[0025] In some embodiments, the core flow rate is the flow rate of coolant flowing into the core.

[0026] In some embodiments, the pool-type sodium-cooled fast reactor may include a primary circuit and multiple main pumps. Multiple main pumps may be arranged in the primary circuit. The symmetric working condition in the embodiment of the present application is a working condition in which the pressure heads of the main pumps are equal, and the asymmetric working condition is a working condition in which the pressure heads of the main pumps are unequal.

[0027] In some embodiments, in step S2, the input of the analysis model can be the fluid resistance characteristics of each component in the primary loop of the pool-type sodium-cooled fast reactor, and its output can include the calculated flow rate of the main pump bypass flowmeter and the calculated flow rate of the core. Generally, the pressure loss when the fluid flows through the component is called resistance. Different components and different flow rates have different pressure losses when the fluid flows through, which is generally called fluid resistance characteristics.

[0028] In some embodiments, a main pump bypass flowmeter may be provided, and a measurement value of the main pump bypass flowmeter may be obtained through actual measurement, and the actual flow rate of the core may be calculated based on the measurement value. In step S3, the actual flow rate of the core may be calculated using the measurement value of the flowmeter under symmetrical working conditions.

[0029] In some embodiments, the method for determining the core flow of a pool-type sodium-cooled fast reactor may also include the following steps: S6: establishing a thermal-hydraulic model of a pool-type sodium-cooled fast reactor under symmetrical operating conditions; S7: determining the calculated temperature at the outlet sodium temperature measuring point of the core using the thermal-hydraulic model and the calculated flow of the core determined in step S2; S8: optimizing the calculated temperature; S9: determining the actual temperature at the outlet sodium temperature measuring point of the core by measurement; S10: comparing the calculated temperature determined in step S8 with the actual temperature determined in step S9; S11: continuing to optimize the thermal-hydraulic model based on the comparison result.

[0030] The method provided in the embodiment of the present application utilizes the thermal-hydraulic model and the calculated flow rate of the core to determine the calculated temperature at the outlet sodium temperature measuring point of the core, and then based on the calculated temperature and the actual temperature at the outlet sodium temperature measuring point of the core, it can be determined whether the thermal-hydraulic model needs to be further optimized, which is beneficial to ensuring the measurement accuracy of the thermal-hydraulic model.

[0031] In some embodiments, the thermal-hydraulic model may be a three-dimensional computational fluid dynamics model (three-dimensional CFD model).

[0032] In some embodiments, the components of the core center area of ​​the pool-type sodium-cooled fast reactor include multiple fuel assemblies and a small number of control rod assemblies, which are generally referred to as the core active region, and the components of the periphery of the core active region include stainless steel components, boron shielding components, etc. Along the radial direction of the core, the core outlet sodium temperature measurement point is generally located at the outermost periphery of the core active region. Along the axial direction of the core, the core outlet sodium temperature measurement point is generally located above the core active region outlet, for example, about several hundred millimeters above the core active region outlet.

[0033] In some embodiments, an analytical model can be used to establish a thermal hydraulic model. When modeling, all components in the core (including fuel components, control rod components, stainless steel components, boron shield components, etc.) can be merged into multiple channels, such as several or dozens of channels, according to the principle of close sodium temperature at the outlet of the component. According to the sodium temperature at the outlet of each channel of the core and the position information of the outlet sodium temperature measuring point of the core calculated by the analytical model, the rough value of the calculated temperature at the outlet sodium temperature measuring point of the core can be determined, and then the three-dimensional fluid area from the component outlet to the outlet sodium temperature measuring point of the core is subjected to fluid mechanics calculation, and the accurate value of the calculated temperature at the outlet sodium temperature measuring point of the core can be determined.

[0034] In some embodiments, the pool-type sodium-cooled fast reactor may further include a thermocouple, which is disposed at an outlet sodium temperature measuring point of the core and is used to measure the actual temperature at the outlet sodium temperature measuring point.

[0035] In some embodiments, in step S11, if the difference between the calculated temperature and the actual temperature under the symmetrical working condition is within the first preset temperature range, the parameters of the thermal hydraulic model can be solidified; if the difference between the calculated temperature and the actual temperature is not within the first preset temperature range, the thermal hydraulic model can continue to be optimized. The first preset temperature range can be set based on experience.

[0036] In some embodiments, in step S8, the optimized temperature is determined using the thermal conductivity differential equation of the thermocouple to further improve the accuracy of the optimized temperature.

[0037] In some embodiments, the thermal conductivity differential equation of the thermocouple may satisfy the following relationship:

[0038]

[0039] Among them, ρ represents the density of the thermocouple, c represents the specific heat capacity of the thermocouple, V represents the volume of the thermocouple, h represents the convection heat transfer coefficient of the thermocouple, A represents the area of ​​the thermocouple, T2 represents the optimized temperature, T1 represents the calculated temperature at the outlet sodium temperature measuring point of the core, and τ represents time.

[0040] In some embodiments, the method for determining the core flow of a pool-type sodium-cooled fast reactor also includes the following steps: S12: Under asymmetric conditions, according to the optimized thermal-hydraulic model determined in step S11 and the core flow determined in step S12, determine the calculated temperature at the outlet sodium temperature measuring point of the core under asymmetric conditions; S13: Optimize the calculated temperature; S14: Determine the actual temperature at the outlet sodium temperature measuring point of the core by measurement; S15: Compare the calculated temperature determined in step S13 with the actual temperature determined in step S14; S16: Determine whether the core flow determined in step S12 is correct based on the comparison result.

[0041] The inventors of the present application discovered that under the condition of asymmetric flow in the primary circuit of a pool-type sodium-cooled fast reactor, there is no linear relationship between the measured value of the flow meter of the bypass flow channel of the primary main pump and the actual flow of the core. At this time, the calculated flow cannot be directly compared through the measured value of the flow meter, but it is necessary to use the calculated temperature at the outlet sodium temperature measuring point of the core for indirect comparison. The embodiment of the present application optimizes the calculated temperature, which is beneficial to reducing the calculation error and improving the accuracy of the calculated temperature obtained; then, the result obtained by comparing the calculated temperature at the outlet sodium temperature measuring point of the core with the actual temperature is used to continue to optimize the thermal-hydraulic model, and the optimization result is relatively reliable.

[0042] In some embodiments, the implementation of steps S12 to S15 is similar to the implementation of steps S7 to S10, and for the sake of brevity, they are not repeated here.

[0043] In some embodiments, in step S16, if the difference between the calculated temperature and the actual temperature under the asymmetric working condition is within the second preset temperature range, it can be determined that the flow rate of the core determined in step S12 is correct; if the difference between the calculated temperature and the actual temperature under the asymmetric working condition is not within the second preset temperature range, it can be determined that the flow rate of the core determined in step S12 is incorrect. The second preset temperature range can be set based on experience.

[0044] In some embodiments, in step S13, the optimized temperature may be determined using a thermal conductivity differential equation of a thermocouple.

[0045] In some embodiments, in step S13, the optimized temperature can be determined using equation (1) in the embodiments of the present application. The specific implementation method and technical effects have been described in detail in the above embodiments and will not be repeated here for the sake of brevity.

[0046] An embodiment of the present application also provides a method for determining the core flow rate of a pool-type sodium-cooled fast reactor. The method is used to determine the core flow rate of a pool-type sodium-cooled fast reactor under an asymmetric operating condition, and includes the following steps: establishing a first model and a second model when the pool-type sodium-cooled fast reactor is under a symmetric operating condition, the core flow rate can be determined by the first model, and the first model and the second model are verified under the symmetric operating condition; the first model and the second model are corrected according to the verification results; when the pool-type sodium-cooled fast reactor is under an asymmetric operating condition, the core flow rate is determined using the first model; and the determined core flow rate under the asymmetric operating condition is verified by the second model to determine the accuracy of the core flow rate.

[0047] The embodiments of the present application can determine whether the first model and the second model need to be corrected to ensure the accuracy of the output results of the first model and the second model by verifying the first model and the second model under symmetric conditions; then, when the pool-type sodium-cooled fast reactor is in an asymmetric condition, the first model can be used to determine the core flow rate to achieve the measurement of the core flow rate under the asymmetric condition; then, the determined core flow rate under the asymmetric condition is verified by the second model, which is beneficial to improve the accuracy of the determined core flow rate.

[0048] In some embodiments, the first model may be an analytical model of the embodiment of the present application, and the second model may be a thermal-hydraulic model of the embodiment of the present application.

[0049] In some embodiments, those skilled in the art may refer to the implementation methods of steps S12 to S16 in the embodiments of the present application to understand the implementation method of verifying the determined core flow under asymmetric conditions through the second model, which will not be repeated here for the sake of brevity.

[0050] In some embodiments, when verifying the first model, the core flow of the pool-type sodium-cooled fast reactor under symmetrical operating conditions is determined by measurement, the measured core flow is compared with the core flow determined by the first model, and the first model is corrected based on the comparison result.

[0051] The embodiments of the present application determine whether the first model needs to be corrected by comparing the core flow determined by measurement with the core flow determined by the first model, thereby ensuring the reliability of the correction of the first model.

[0052] In some embodiments, the temperature at the outlet sodium temperature measuring point of the core is used to verify the second model to ensure the accuracy and reliability of the verification result.

[0053] In some embodiments, those skilled in the art may refer to the implementation methods of steps S6 to S11 in the embodiments of the present application to understand the implementation method of verifying the second model using the temperature at the outlet sodium temperature measuring point of the core, which will not be elaborated here for the sake of brevity.

[0054] In some embodiments, the temperature at the outlet sodium temperature measuring point of the core can be determined by the core flow determined by the first model and the second model.

[0055] In some embodiments, the temperature at the outlet sodium temperature measuring point of the core is determined by measurement; the temperature at the outlet sodium temperature measuring point determined by the second model is optimized, and the optimized temperature is compared with the measured temperature, and it is determined whether the second model needs to be corrected based on the comparison result.

[0056] The embodiment of the present application determines whether the second model needs to be corrected by comparing the optimized temperature with the measured temperature based on the comparison result obtained, thereby ensuring the reliability of the correction result.

[0057] In some embodiments, the temperature at the outlet sodium temperature measuring point determined by the second model can be optimized using the thermal conduction differential equation of the thermocouple to improve the accuracy of the temperature at the outlet sodium temperature measuring point determined by the second model. The specific optimization method has been described in detail in the previous embodiments and will not be repeated here.

[0058] Regarding the embodiments of the present application, it should also be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other to obtain new embodiments.

[0059] The above are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto. The protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for determining the core flow rate of a pool-type sodium-cooled fast reactor, the method being used to determine the core flow rate of the pool-type sodium-cooled fast reactor under an asymmetric operating condition, characterized in that: It includes the following steps: S1: establishing an analysis model of the pool-type sodium-cooled fast reactor when the pool-type sodium-cooled fast reactor is in a symmetrical operating condition; S2: determining the calculated flow rate of the core according to the analytical model of the pool-type sodium-cooled fast reactor; S3: determining the actual flow rate of the core by measuring; S4: comparing the calculated flow rate of the core determined in step S2 with the actual flow rate of the core determined in step S3; S5: According to the comparison result, the analysis model of the pool-type sodium-cooled fast reactor is corrected; S17: When the pool-type sodium-cooled fast reactor is in an asymmetric operating condition, the flow rate of the core is determined using the revised analysis model of the pool-type sodium-cooled fast reactor determined in step S5.

2. The method according to claim 1, characterized in that The following steps are also included: S6: Under symmetrical working conditions, a thermal hydraulic model of the pool-type sodium-cooled fast reactor is established; S7: Determine the calculated temperature at the outlet sodium temperature measuring point of the core by using the thermal hydraulic model and the calculated flow rate of the core determined in step S2; S8: Optimizing the calculated temperature; S9: determining the actual temperature at the outlet sodium temperature measuring point of the core by measuring; S10: comparing the calculated temperature determined in step S8 with the actual temperature determined in step S9; S11: According to the comparison result, the thermal-hydraulic model is further optimized.

3. The method according to claim 2, characterized in that In step S8, the optimized temperature is determined using the thermal conductivity differential equation of the thermocouple.

4. The method according to claim 2, characterized in that: The following steps are also included: S12: Under the asymmetric working condition, according to the optimized thermal hydraulic model determined in step S11 and the flow rate of the core determined in step S17, determining the calculated temperature at the outlet sodium temperature measuring point of the core under the asymmetric working condition; S13: Optimizing the calculated temperature; S14: determining the actual temperature at the outlet sodium temperature measuring point of the core by measuring; S15: comparing the calculated temperature determined in step S13 with the actual temperature determined in step S14; S16: Based on the comparison result, determine whether the flow rate of the core determined in step S17 is correct.

5. The method according to claim 4, characterized in that In step S13, the optimized temperature is determined using the thermal conduction differential equation of the thermocouple.

6. A method for determining the core flow rate of a pool-type sodium-cooled fast reactor, the method being used to determine the core flow rate of the pool-type sodium-cooled fast reactor under an asymmetric operating condition, characterized in that: It includes the following steps: A first model and a second model are established when the pool-type sodium-cooled fast reactor is in a symmetrical operating condition. The core flow rate can be determined by the first model, And under the symmetrical working condition, verifying the first model and the second model; Modifying the first model and the second model according to the verification result; When the pool-type sodium-cooled fast reactor is in an asymmetric operating condition, determining the core flow rate by using the first model; The core flow rate determined under the asymmetric operating condition is verified by the second model to determine the accuracy of the core flow rate.

7. The method according to claim 6, characterized in that When verifying the first model, the core flow rate of the pool-type sodium-cooled fast reactor under the symmetrical operating condition is determined by measurement. comparing the core flow rate determined by measurement with the core flow rate determined by the first model, According to the comparison result, the first model is modified.

8. The method according to claim 6, characterized in that The second model is verified using the temperature at the outlet sodium temperature measuring point of the core.

9. The method according to claim 8, characterized in that The temperature at the outlet sodium temperature measuring point of the core is determined by the core flow determined by the first model and the second model.

10. The method according to claim 9, characterized in that Determine the temperature at the outlet sodium temperature measuring point of the core by measuring; The temperature at the outlet sodium temperature measuring point determined by the second model is optimized, and the optimized temperature is compared with the measured temperature, and it is determined whether the second model needs to be corrected according to the comparison result.

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