Method for determining the core flow of a pool-type sodium-cooled fast reactor
By establishing analytical and thermal-hydraulic models in a pool-type sodium-cooled fast reactor and optimizing the flow meter and outlet sodium temperature measurement point, the problem of core flow measurement under asymmetric conditions was solved, and reliable calculation and safety assurance under symmetric and asymmetric conditions were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA INSTITUTE OF ATOMIC ENERGY
- Filing Date
- 2024-10-10
- Publication Date
- 2026-07-14
AI Technical Summary
Existing technologies cannot directly measure the core flow rate under asymmetric conditions in the primary loop of a pool-type sodium-cooled fast reactor, resulting in inaccurate flow rate calculations and affecting the core cooling effect and safety.
An analytical model was established under symmetrical operating conditions. The model was optimized and corrected by measuring flow meters and using a thermal-hydraulic model to determine the core flow rate. The corrected model was then applied to calculate the core flow rate under asymmetrical operating conditions. The model was then validated and optimized using the temperature of the outlet sodium temperature measuring point.
To ensure the reliability of core flow calculation results under symmetrical and asymmetrical operating conditions, reduce calculation errors, and improve the accuracy and safety of core flow measurement.
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Figure CN119294296B_ABST
Abstract
Description
Technical Field
[0001] The embodiments of this 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 Technology
[0002] The statements herein are provided only as background information in connection with this application and do not necessarily constitute prior art.
[0003] The primary cooling system of a pool-type sodium-cooled fast reactor (SLFR) can include two or more parallel loops, each arranged within the main vessel of the SLFR to form an integrated pool structure. The coolant in the primary cooling system is typically liquid metallic sodium. The flow path of the main cooling channel for cooling the reactor core in each loop is as follows: sodium pumps draw sodium from the cold sodium pool, deliver it through the primary loop pressure piping into the grid header, cool the fuel assemblies, and then flow out of the core into the hot sodium pool; the hot sodium flows downwards from the upper inlet of the intermediate heat exchanger through the pipes and flows into the cold sodium pool from the lower outlet.
[0004] During the cooling process, it is crucial to determine the cooling effect of the primary loop by measuring the coolant flow rate. However, due to the structural characteristics of the primary loop in pool-type sodium-cooled fast reactors, it is currently impossible to install a measuring device in the primary loop for directly measuring the core flow rate or the primary loop flow rate. Summary of the Invention
[0005] A brief overview of this application is provided below to offer a basic understanding of certain aspects thereof. It should be understood that this overview is not an exhaustive summary of the application. It is not intended to identify key or essential parts of the application, nor is it intended to limit its scope. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.
[0006] In a first aspect, embodiments of this application provide a method for determining the core flow rate of a pool-type sodium-cooled fast reactor (NSCFR). The method is used to determine the core flow rate of the NSCFR under asymmetric operating conditions, and includes the following steps: S1: Establishing an analytical model of the NSCFR under symmetric operating conditions; S2: Determining the calculated core flow rate based on the analytical model of the NSCFR; S3: Determining the actual core flow rate by measurement; S4: Comparing the calculated core flow rate determined in step S2 with the actual core flow rate determined in step S3; S5: Correcting the analytical model of the NSCFR based on the comparison results; S17: Determining the core flow rate using the corrected analytical model of the NSCFR determined in step S5 under asymmetric operating conditions.
[0007] Secondly, embodiments of this application also provide 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 asymmetric operating conditions, and includes the following steps: establishing a first model and a second model under symmetric operating conditions; determining the core flow rate using the first model; verifying the first model and the second model under symmetric operating conditions; correcting the first model and the second model based on the verification results; determining the core flow rate using the first model under asymmetric operating conditions; and verifying the determined core flow rate under asymmetric operating conditions using the second model to determine the accuracy of the core flow rate.
[0008] The method provided in the embodiments of this application establishes an analytical model of the pool-type sodium-cooled fast reactor under symmetrical operating conditions. Then, based on the comparison between the calculated and actual core flow rates, the analytical model is corrected. The corrected analytical model is then used to determine the core flow rate under asymmetrical operating conditions. This helps ensure that the core flow rate of the pool-type sodium-cooled fast reactor is calculable under both symmetrical and asymmetrical operating conditions, and that the calculation results are relatively reliable. Furthermore, it helps ensure that the impact of the core flow rate on core safety is knowable.
[0009] These and other advantages of this application will become more apparent from the following detailed description of preferred embodiments in conjunction with the accompanying drawings. Attached Figure Description
[0010] To further illustrate the above and other advantages and features of this application, the specific embodiments of this application will be described in more detail below with reference to the accompanying drawings. The drawings, together with the following detailed description, are included in and form a part of this specification. Elements having the same function and structure are indicated by the same reference numerals. It should be understood that these drawings only depict typical examples of this application and should not be considered as limiting the scope of this application.
[0011] Figure 1 This is a flowchart illustrating a method for determining the core flow rate of a pool-type sodium-cooled fast reactor according to an embodiment of this application.
[0012] It should be noted that the accompanying drawings are not necessarily drawn to scale, but are shown only in a schematic manner without affecting the reader's understanding. Detailed Implementation
[0013] Exemplary embodiments of this application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of actual implementations are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the development of any such actual embodiment to achieve the developer's specific goals, such as complying with constraints related to the system and business, and these constraints may vary depending on the implementation. Furthermore, it should be understood that while development work can be very complex and time-consuming, such development work is merely a routine task for those skilled in the art who benefit from the content of this application.
[0014] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the equipment structure and / or processing steps closely related to the solution according to this application are shown in the accompanying drawings, while other details that are not closely related to this application are omitted.
[0015] The following disclosure provides several different implementations or examples for carrying out this application. To simplify the disclosure of this application, specific examples of components and methods are described below. Of course, these are merely examples and are not intended to limit this application. In the description of the embodiments of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0016] In related technologies, when determining the core flow rate of a pool-type sodium-cooled fast reactor, for symmetrical operating conditions where the heads of all primary pumps are equal, the core flow rate can be calculated from the flowmeter measurements in the main pump bypass channels. However, for asymmetrical operating conditions where the heads of all primary pumps are unequal, since two or more loops are retained in the primary cooling system, it is impossible to calculate the core flow rate from the flowmeter measurements in the main pump bypass channels. Currently, there is no method for measuring the core flow rate of a pool-type sodium-cooled fast reactor under asymmetrical primary flow conditions.
[0017] To address the aforementioned problems, embodiments of this application provide a method for determining the core flow rate of a pool-type sodium-cooled fast reactor. This method can be used to determine the core flow rate of a pool-type sodium-cooled fast reactor under asymmetric operating conditions, such as... Figure 1 As shown, the method may include at least the following steps.
[0018] S1: Establish an analytical model for a pool-type sodium-cooled fast reactor under symmetrical operating conditions.
[0019] S2: Determine the calculated flow rate of the reactor core based on the analytical model of the pool-type sodium-cooled fast reactor.
[0020] S3: Determine the actual flow rate of the reactor core through measurement.
[0021] S4: Compare the calculated core flow rate determined in step S2 with the actual core flow rate determined in step S3.
[0022] S5: Based on the comparison results, the analytical model of the pool-type sodium-cooled fast reactor is revised.
[0023] S17: Under asymmetric operating conditions, determine the core flow rate using the modified analytical model of the pool-type sodium-cooled fast reactor determined in step S5.
[0024] The method provided in the embodiments of this application establishes an analytical model of the pool-type sodium-cooled fast reactor under symmetrical operating conditions. Then, based on the comparison between the calculated and actual core flow rates, the analytical model is corrected. The corrected analytical model is then used to determine the core flow rate under asymmetrical operating conditions. This helps ensure that the core flow rate of the pool-type sodium-cooled fast reactor is calculable under both symmetrical and asymmetrical operating conditions, and that the calculation results are relatively reliable. Furthermore, it helps ensure that the impact of the core flow rate on core safety is knowable.
[0025] In some embodiments, the core flow rate is the flow rate of coolant flowing into the core.
[0026] In some embodiments, a pool-type sodium-cooled fast reactor may include a primary loop and multiple main pumps. The multiple main pumps may be arranged in the primary loop. In the embodiments of this application, the symmetrical operating condition refers to the condition where the head of each main pump is equal, and the asymmetrical operating condition refers to the condition where the head of each main pump is unequal.
[0027] In some embodiments, in step S2, the input to the analysis model can be the fluid resistance characteristics of each component in the primary loop of a 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 reactor core. The pressure loss of fluid flowing through a component is generally called resistance. The pressure loss varies depending on the component and the flow velocity; this is generally referred to as fluid resistance characteristics.
[0028] In some embodiments, a main pump bypass flow meter can be installed. The measured value of the main pump bypass flow meter is obtained through actual measurement, and the actual flow rate of the reactor core can be calculated based on this measured value. In step S3, the actual flow rate of the reactor core can be calculated using the flow meter measurement value under symmetrical operating conditions.
[0029] In some embodiments, the method for determining the core flow rate of a pool-type sodium-cooled fast reactor may further include the following steps: S6: Establishing a thermal-hydraulic model of the pool-type sodium-cooled fast reactor under symmetrical operating conditions; S7: Determining the calculated temperature at the sodium temperature measuring point at the core outlet using the thermal-hydraulic model and the calculated core flow rate determined in step S2; S8: Optimizing the calculated temperature; S9: Determining the actual temperature at the sodium temperature measuring point at the core outlet by measurement; S10: Comparing the calculated temperature determined in step S8 with the actual temperature determined in step S9; S11: Further optimizing the thermal-hydraulic model based on the comparison results.
[0030] The method provided in the embodiments of this application uses a thermal-hydraulic model and the calculated flow rate of the reactor core to determine the calculated temperature at the sodium temperature measuring point at the reactor core outlet. Then, based on the calculated temperature and the actual temperature at the sodium temperature measuring point at the reactor core outlet, it can be determined whether the thermal-hydraulic model needs to be further optimized, which helps to ensure the measurement accuracy of the thermal-hydraulic model.
[0031] In some embodiments, the thermal-hydraulic model can be a three-dimensional computational fluid dynamics model (three-dimensional CFD model).
[0032] In some embodiments, the core central region of a pool-type sodium-cooled fast reactor comprises multiple fuel assemblies and a small number of control rod assemblies, generally referred to as the core active region. The periphery of the core active region includes stainless steel assemblies, boron shielding assemblies, etc. Along the radial direction of the core, the core outlet sodium temperature measuring point is generally located at the outermost edge of the core active region. Along the axial direction of the core, the core outlet sodium temperature measuring point is generally located above the core active region outlet, for example, approximately 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. During modeling, based on the principle of similar sodium temperatures at the component outlets, all components within the reactor core (including fuel assemblies, control rod assemblies, stainless steel assemblies, boron shielding assemblies, etc.) can be grouped into multiple channels, such as several or dozens of channels. Based on the sodium temperatures at the outlets of each core channel calculated by the analytical model and the location information of the sodium temperature measurement points at the core outlets, a rough value of the calculated temperature at the core outlet sodium temperature measurement points can be determined. Then, hydrodynamic calculations are performed on the three-dimensional fluid region from the component outlets to the core outlet sodium temperature measurement points to determine the precise value of the calculated temperature at the core outlet sodium temperature measurement points.
[0034] In some embodiments, the pool-type sodium-cooled fast reactor may further include a thermocouple disposed at the outlet sodium temperature measuring point of the reactor core for measuring 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 symmetrical operating conditions is within a first preset temperature range, the parameters of the thermal-hydraulic model can be fixed; 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 empirically.
[0036] In some embodiments, in step S8, the thermal conductivity differential equation of the thermocouple is used to determine the optimized temperature to further improve the accuracy of the optimized temperature.
[0037] In some embodiments, the thermal conductivity differential equation of a thermocouple can satisfy the following relationship:
[0038]
[0039] Where 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 convective 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 sodium temperature measuring point at the core outlet, and τ represents time.
[0040] In some embodiments, the method for determining the core flow rate of a pool-type sodium-cooled fast reactor further includes the following steps: S12: Under asymmetric operating conditions, based on the optimized thermo-hydraulic model determined in step S11 and the core flow rate determined in step S12, determine the calculated temperature at the sodium temperature measuring point at the core outlet under asymmetric operating conditions; S13: Optimize the calculated temperature; S14: Determine the actual temperature at the sodium temperature measuring point at the core outlet by measurement; S15: Compare the calculated temperature determined in step S13 with the actual temperature determined in step S14; S16: Based on the comparison result, determine whether the core flow rate determined in step S12 is correct.
[0041] The inventors of this application discovered that, under asymmetrical flow conditions in the primary loop of a pool-type sodium-cooled fast reactor, the measured value of the flowmeter in the bypass channel of the primary loop main pump does not have a linear relationship with the actual flow rate of the reactor core. In this case, it is impossible to directly compare the calculated flow rate using the flowmeter measurement value. Instead, it is necessary to use the calculated temperature at the sodium temperature measuring point at the reactor core outlet for indirect comparison. The embodiments of this application optimize the calculated temperature, which helps to reduce calculation errors and improve the accuracy of the obtained calculated temperature. Then, using the results obtained by comparing the calculated temperature at the sodium temperature measuring point at the reactor core outlet with the actual temperature, the thermal-hydraulic model is further optimized, and the optimization results are relatively reliable.
[0042] In some embodiments, steps S12 to S15 are implemented in a similar manner to steps S7 to S10, and for the sake of brevity, they will not be described again here.
[0043] In some embodiments, in step S16, if the difference between the calculated temperature and the actual temperature under asymmetric operating conditions is within a second preset temperature range, the core flow rate determined in step S12 can be determined to be correct; if the difference between the calculated temperature and the actual temperature under asymmetric operating conditions is not within the second preset temperature range, the core flow rate determined in step S12 can be determined to be incorrect. The second preset temperature range can be set empirically.
[0044] In some embodiments, in step S13, the thermal conductivity differential equation of the thermocouple can be used to determine the optimized temperature.
[0045] In some embodiments, in step S13, the optimized temperature can be determined using the relation (1) in the embodiments of this 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] Embodiments of this application also provide a method for determining the core flow rate of a pool-type sodium-cooled fast reactor (SCFR). The method is used to determine the core flow rate of the SCFR under asymmetric operating conditions, and includes the following steps: establishing a first model and a second model for the SCFR under symmetric operating conditions; determining the core flow rate using the first model; verifying the first and second models under symmetric operating conditions; correcting the first and second models based on the verification results; determining the core flow rate using the first model under asymmetric operating conditions; and verifying the determined core flow rate under asymmetric operating conditions using the second model to determine the accuracy of the core flow rate.
[0047] The embodiments of this application verify the first and second models under symmetrical operating conditions to determine whether corrections are needed, thus ensuring the accuracy of the output results of the first and second models. Then, when the pool-type sodium-cooled fast reactor is under asymmetrical operating conditions, the core flow rate can be determined using the first model to achieve measurement of the core flow rate under asymmetrical operating conditions. Then, the determined core flow rate under asymmetrical operating conditions is verified using the second model, which helps to improve the accuracy of the determined core flow rate.
[0048] In some embodiments, the first model may be the analysis model of the present application embodiment, and the second model may be the thermal-hydraulic model of the present application embodiment.
[0049] In some embodiments, those skilled in the art can refer to the implementation of steps S12 to S16 in the embodiments of this application to understand the implementation of verifying the determined core flow rate under asymmetric operating conditions through the second model. For the sake of brevity, it will not be described in detail here.
[0050] In some embodiments, when validating the first model, the core flow rate of the pool-type sodium-cooled fast reactor under symmetrical operating conditions is determined by measurement, the measured core flow rate is compared with the core flow rate determined by the first model, and the first model is corrected based on the comparison result.
[0051] The embodiments of this application determine whether the first model needs to be corrected by comparing the measured core flow rate with the core flow rate determined by the first model, thereby ensuring the reliability of the correction of the first model.
[0052] In some embodiments, the temperature at the sodium temperature measurement point at the reactor core outlet is used to verify the second model to ensure the accuracy and reliability of the verification results.
[0053] In some embodiments, those skilled in the art can refer to the implementation of steps S6 to S11 in the embodiments of this application to understand the implementation of using the temperature at the sodium temperature measuring point at the core outlet to verify the second model. For the sake of brevity, it will not be described in detail here.
[0054] In some embodiments, the temperature at the core outlet sodium temperature measurement point can be determined using the core flow rate determined by the first model and the second model.
[0055] In some embodiments, the temperature at the sodium temperature measuring point at the reactor core exit is determined by measurement; the temperature at the sodium temperature measuring point at the exit determined by the second model is optimized, and the optimized temperature is compared with the measured temperature, and the second model is determined to be corrected based on the comparison result.
[0056] The embodiments of this application determine whether the second model needs to be corrected by comparing the optimized temperature with the measured temperature, thus 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 conductivity differential equation of the thermocouple, so as 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 this application, it should also be noted that, without conflict, the embodiments of this application and the features in the embodiments can be combined with each other to obtain new embodiments.
[0059] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. The scope of protection of this application shall be determined by the 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 asymmetric operating conditions, characterized in that, It includes the following steps: S1: Under the condition that the pool-type sodium-cooled fast reactor is in symmetrical operation, establish an analytical model of the pool-type sodium-cooled fast reactor; S2: Determine the calculated flow rate of the reactor core based on the analytical model of the pool-type sodium-cooled fast reactor; S3: Determine the actual flow rate of the reactor core by measurement; 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; S5: Based on the comparison results, the analytical model of the pool-type sodium-cooled fast reactor is modified; S17: When the pool-type sodium-cooled fast reactor is under asymmetric operating conditions, the core flow rate is determined using the modified analytical model of the pool-type sodium-cooled fast reactor determined in step S5. It also includes the following steps: S6: Under symmetrical operating conditions, establish the thermal-hydraulic model of the pool-type sodium-cooled fast reactor; S7: Using the aforementioned thermal-hydraulic model and the calculated flow rate of the reactor core determined in step S2, determine the calculated temperature at the sodium temperature measuring point at the reactor core outlet. S8: Optimize the calculated temperature; S9: Determine the actual temperature at the sodium temperature measuring point at the reactor core outlet by means of measurement; S10: Compare the calculated temperature determined in step S8 with the actual temperature determined in step S9; S11: Based on the comparison results, the thermal-hydraulic model is further optimized; It also includes the following steps: S12: Under asymmetric operating conditions, based on the optimized thermal-hydraulic model determined in step S11 and the core flow rate determined in step S17, determine the calculated temperature at the core outlet sodium temperature measuring point under asymmetric operating conditions. S13: Optimize the calculated temperature; S14: Determine the actual temperature at the sodium temperature measuring point at the reactor core outlet by means of measurement; S15: Compare the calculated temperature determined in step S13 with the actual temperature determined in step S14; S16: Based on the comparison results, determine whether the core flow rate determined in step S17 is correct.
2. The method according to claim 1, characterized in that, In step S8, the thermal conductivity differential equation of the thermocouple is used to determine the optimized temperature.
3. The method according to claim 1, characterized in that, In step S13, the optimized temperature is determined using the thermal conductivity differential equation of the thermocouple.
4. 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 asymmetric operating conditions, characterized in that... It includes the following steps: A first model and a second model were established under symmetrical operating conditions for the pool-type sodium-cooled fast reactor. The core flow rate can be determined using the first model. And the first model and the second model are verified under the symmetrical working condition; The first model and the second model are revised based on the verification results; Under asymmetric operating conditions, the core flow rate of the pool-type sodium-cooled fast reactor is determined using the first model. The core flow rate determined under the asymmetric operating condition is verified using the second model to determine the accuracy of the core flow rate. When validating the first model, the core flow rate of the pool-type sodium-cooled fast reactor under the symmetrical operating condition was determined by measurement. The measured core flow rate is compared with the core flow rate determined by the first model. Based on the comparison results, the first model is modified; The second model was verified using the temperature at the sodium temperature measuring point at the reactor core's outlet. The core flow rate determined by the first model and the second model are used to determine the temperature at the sodium temperature measurement point at the core outlet. The temperature at the sodium temperature measuring point at the reactor core outlet 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. Based on the comparison result, it is determined whether the second model needs to be corrected.