Device for measuring sodium flow friction resistance of sodium-cooled fast reactor core assembly during natural circulation

Abstract

The present disclosure relates to the technical field of fast reactor core assembly module, and particularly relates to a device and method for measuring sodium flow frictional resistance of a sodium-cooled fast reactor core assembly during natural circulation. The device for measuring sodium flow frictional resistance of a sodium-cooled fast reactor core assembly during natural circulation comprises: a core assembly module, which comprises a wire-wound fuel rod and liquid sodium flowing around the wire-wound fuel rod; a cooling downcomer, which is suitable for cooling sodium flow in the downcomer and is in communication with both ends of the wire-wound fuel rod; a heating module, which is suitable for heating the core assembly module so that the liquid sodium forms a natural circulation loop in the core assembly module, the connecting channel and the cooling downcomer; a measuring module, which is suitable for measuring the temperature distribution and flow of the metal sodium in the natural circulation loop; and a calculation module, which is suitable for calculating the frictional resistance of the sodium flow in the core assembly module according to the temperature distribution and flow.

Description

Technical Field

[0001] This disclosure relates to the field of fast reactor core assembly module technology, and in particular to a measuring device and method for measuring the sodium flow frictional resistance during natural circulation of a sodium-cooled fast reactor core assembly. Background Technology

[0002] Following a power outage or emergency shutdown due to a main pump malfunction, the safe discharge of residual heat from the reactor core remains one of the most critical safety issues for large reactors. As sodium-cooled fast reactors (SNCRs) evolve towards larger scale and commercialization, higher demands are being placed on both safety and economic efficiency—two seemingly contradictory aspects. Ensuring that the cladding and fuel temperatures remain within safe limits during natural circulation of residual heat in SNCR core assemblies, under conditions of smaller sodium pools, higher power density, and more compact core module structures, depends on a thorough understanding of the natural circulation of sodium flow within the SNCR core assemblies.

[0003] In a sodium-cooled fast reactor (NSCRT) following an emergency shutdown due to core coolant loss, the sodium flow within the core assemblies transitions from forced circulation to natural circulation. The sodium flow velocity through the core assemblies rapidly decreases to 1-3% of the design flow rate, while the Reynolds number (Re) of the sodium flow through the wire rod bundle assemblies remains between 300 and 800. As the sodium flow velocity through the assemblies decreases, the flow transitions from turbulent to laminar flow in the transition zone. The frictional resistance of the assemblies to the sodium flow gradually changes from being proportional to the square of the sodium flow velocity to being proportional to the sodium flow velocity itself, with the rate of decrease varying. However, the sodium flow in other components outside the assemblies remains turbulent, and their flow resistance to the sodium flow is proportional to the square of the sodium flow velocity. The flow resistance of these other components to the sodium flow decreases rapidly. Therefore, when the sodium flow velocity decreases to 1-3% of the design flow rate, the frictional resistance pressure drop of the wire rod bundle assembly to the sodium flow is 1-3% of its design flow rate, while the local resistance pressure drop of other components outside the assembly to the sodium flow is 0.02-0.1% of its design flow rate. The frictional resistance pressure drop of the wire rod bundle assembly to the sodium flow accounts for approximately 90% of the total pressure drop in the entire natural circulation path. In the natural circulation of sodium flow through the wire rod bundle assembly, the natural circulation flow resistance determines the natural circulation sodium flow rate, and consequently, the power at which the passive residual heat removal system removes core decay residual heat from the core. Therefore, determining the frictional resistance characteristics of the wire rod bundle assembly during natural circulation is crucial for calculating the sodium flow rate through the core assembly under extreme accident conditions in a sodium-cooled fast reactor core. It is one of the core parameters required for accurately calculating the cooling power of the passive residual heat removal system under accident conditions, and it has significant reference value for the design and verification of the passive residual heat removal system in a sodium-cooled fast reactor.

[0004] In related technologies, there are no experimental studies on the frictional resistance of sodium flow during natural circulation of wire rod bundle assemblies. There are three main reasons for this: First, sodium flow is chemically reactive and flammable / explosive. A leak of high-temperature sodium flow would immediately ignite a sodium fire, making experimental measurements very difficult. Second, installing pressure tapping and measuring equipment is difficult. To match the actual operating conditions of a sodium-cooled fast reactor, the sodium flow temperature must be between 300 and 600°C during natural circulation experiments. Furthermore, the geometry of the wire rod bundle assembly is very complex. In addition, different components must form a very compact and complete inter-box channel similar to that of an actual fast reactor. The possibility of sodium flow solidifying and blocking at low temperatures must also be considered. Therefore, it is impossible to install pressure taps on the assembly box walls, nor is there sufficient space to arrange them. The pressure tapping tube, with its preheating and insulation structure, presents a significant challenge to the differential pressure transmitter due to its high temperature of 600℃. Third, even if pressure measuring equipment can be installed, accurately measuring the frictional resistance of sodium flowing through the wire rod assembly during natural circulation is difficult. Firstly, during natural circulation, the sodium flow velocity is very low, with a Re number of around 300. Therefore, the frictional resistance pressure drop of the rod assembly against the sodium flow is also very low, ranging from 60Pa to 200Pa, or 6 to 20 mm of water column. Accurately measuring such a small frictional resistance pressure drop places high demands on the differential pressure sensor. Secondly, the sodium flow within the assembly experiences a temperature rise of 100 to 200℃ during natural circulation. The temperature change of the sodium flow must be measured to determine the static pressure generated by the sodium flow within the assembly, posing a significant challenge to directly measuring the frictional resistance of the assembly against the sodium flow. Summary of the Invention

[0005] To address at least one of the technical problems mentioned above or in other aspects, this disclosure provides a measuring device and method for measuring the frictional resistance of sodium flow during natural circulation of a sodium-cooled fast reactor core assembly, which can conveniently and accurately measure the frictional resistance of the core assembly to sodium flow during natural circulation.

[0006] According to one aspect of the inventive concept of this disclosure, a measuring device for sodium flow frictional resistance during natural circulation of a sodium-cooled fast reactor core assembly is provided, comprising:

[0007] The core assembly module includes filament-wound fuel rods and liquid sodium flowing around the filament-wound fuel rods;

[0008] The cooling descending channel is suitable for cooling the sodium flow within the channel, and its two ends are respectively connected to the two ends of the wound fuel rod;

[0009] A heating module is suitable for heating the core assembly module to enable the liquid sodium to form a natural circulation loop within the core assembly module, the connecting channel, and the cooling descent channel;

[0010] The measurement module is suitable for measuring the temperature distribution and flow rate of metallic sodium in a natural circulation loop; and

[0011] The calculation module is suitable for calculating the frictional resistance of sodium flow within the core assembly module based on the temperature distribution and the flow rate.

[0012] According to another aspect of the inventive concept of this disclosure, a method for measuring the sodium flow frictional resistance during natural circulation of a sodium-cooled fast reactor core assembly is provided, comprising:

[0013] Obtain the temperature field and sodium flow rate of metallic sodium in the natural circulation loop;

[0014] The gravitational field of the sodium flow in the natural circulation loop is obtained using the temperature field; the driving force formed by the gravity difference during the natural circulation of the sodium flow is obtained using the gravitational field; and other resistances to the sodium flow are obtained using the flow rate of the sodium flow.

[0015] The frictional resistance of the core assembly module to the sodium flow during natural circulation is obtained using the driving force and the other resistances.

[0016] The apparatus and method for measuring the frictional resistance of sodium flow during natural circulation of a sodium-cooled fast reactor core assembly according to the embodiments of this disclosure abandon the traditional method of directly measuring the frictional resistance of the wire rod bundle assembly using a differential pressure sensor. Instead, it utilizes the driving force formed by the gravity difference of the fluid in natural circulation flow and the resistance experienced by the fluid in natural circulation to balance the frictional resistance. By measuring the temperature field and flow rate of the sodium flow in the natural circulation loop, the frictional resistance of the sodium flow passing through the geometry under test during natural circulation can be calculated. This method can accurately and conveniently obtain the frictional resistance of the sodium flow under different natural circulation conditions of the assembly. Attached Figure Description

[0017] Figure 1 This is a block diagram illustrating the operating principle of a device for measuring the sodium flow frictional resistance during natural circulation of a sodium-cooled fast reactor core assembly according to an exemplary embodiment of the present disclosure; and

[0018] Figure 2 This is a flowchart of a method for measuring the sodium flow frictional resistance during natural circulation of a sodium-cooled fast reactor core assembly according to an exemplary embodiment of the present disclosure.

[0019] The meanings of the reference numerals in the above figures are as follows:

[0020] 1-Core assembly module;

[0021] 2-Cooling descent channel;

[0022] 3-Upper connection channel;

[0023] 4- Lower connection channel;

[0024] 5-Electromagnetic flowmeter. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0026] However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of embodiments of this disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this disclosure.

[0027] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The term "comprising" as used herein indicates the presence of structures, features, steps, or operations, but does not exclude the presence or addition of one or more other features.

[0028] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). Similarly, when using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0029] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0030] Figure 1 This is a block diagram illustrating the working principle of a device for measuring the frictional resistance of sodium flow during natural circulation of a sodium-cooled fast reactor core assembly according to an exemplary embodiment of the present disclosure.

[0031] According to one aspect of the inventive concept of this disclosure, a device for measuring the sodium flow frictional resistance during natural circulation of a sodium-cooled fast reactor core assembly is provided, such as... Figure 1 As shown, the measurements include: core assembly module 1, cooling descent channel 2, measurement module, and calculation module.

[0032] According to some embodiments of this disclosure, core assembly module 1 includes filament-wound fuel rods and liquid sodium flowing around the filament-wound fuel rods.

[0033] According to some embodiments of this disclosure, the two ends of the cooling descending channel 2 are respectively connected to the two ends of the wound fuel rod, which is suitable for cooling the sodium flow in the channel.

[0034] According to some embodiments of this disclosure, the heating module is adapted to heat the core assembly module 1 to form a natural circulation loop of liquid sodium within the core assembly module 1, the connection channel, and the cooling descent channel.

[0035] According to some embodiments of this disclosure, the measurement module is suitable for measuring the temperature distribution and flow rate of metallic sodium in a natural circulation loop.

[0036] According to some embodiments of this disclosure, the calculation module is adapted to calculate the frictional resistance of the sodium flow within the core assembly module 1 based on temperature distribution and flow rate.

[0037] In this embodiment, the method of directly measuring the frictional resistance of the wire rod bundle assembly using a differential pressure sensor is abandoned. Instead, the driving force formed by the gravity difference of the fluid in natural circulation flow is balanced with the resistance experienced by the fluid in natural circulation. By measuring the temperature field and flow rate of the sodium flow in the natural circulation loop, the frictional resistance of the sodium flow passing through the geometry under test during natural circulation can be calculated. This method can accurately and conveniently obtain the frictional resistance of the component to the sodium flow under different natural circulation conditions.

[0038] According to some embodiments of this disclosure, the core assembly module 1 is a sodium-cooled fast reactor wire bundle assembly to be tested. The core assembly module 1, the upper connecting channel 3, the cooling descending channel 2 and the lower connecting channel 4 form a complete loop to simulate the flow of metallic sodium during natural circulation in the core assembly.

[0039] According to some embodiments of this disclosure, in order to facilitate the measurement of the frictional resistance of the sodium flow to the coiled rod assembly during natural circulation, the experimental setup can measure the temperature of the sodium flow at different axial positions of the component under test and at different positions of the experimental loop. The distance between adjacent temperature measuring points along the axial direction and the distance between adjacent temperature measuring points along the sodium flow direction in the experimental loop should not be too large. The experimental setup can also measure the flow velocity of the sodium flow through the component under test and the flow velocity of the sodium flow through different sections of the experimental loop.

[0040] In this embodiment, after the sodium flow establishes a stable natural circulation within the wire rod bundle assembly (combustion module), the temperature field of the sodium flow throughout the natural circulation loop is first measured using thermocouples. This allows the determination of the gravitational field distribution of the sodium flow throughout the natural circulation loop. The gravitational field is then integrated along the height direction of the natural circulation loop, for example, H... up and H downThe driving force generated by the gravity difference during natural circulation of sodium flow can be obtained. Then, an electromagnetic flowmeter is used to measure the volumetric flow rate of sodium in the natural circulation loop, thereby calculating the flow resistance of sodium flow through components other than the component under test in the natural circulation loop. Finally, by subtracting the calculated flow resistance generated by sodium flow through components other than the component under test in the natural circulation loop from the calculated driving force, the frictional resistance of the component under test to sodium flow during natural circulation can be obtained.

[0041] According to some embodiments of this disclosure, such as Figure 1 As shown, the sodium stream absorbs heat and heats up within the simulated core assembly experimental section, forming an endothermic rising section. It then releases heat and cools down within the upper connecting pipe and cooling descending channel, forming a cooling descending section. For example, the sodium stream's temperatures before and after the endothermic rising section are 250°C and 530°C, respectively. After cooling through the upper connecting channel, the sodium stream's temperatures before and after entering the cooling descending channel are 400°C and 250°C, respectively. The sodium stream absorbs heat Q and flows upwards within core assembly module 1, and the height of the sodium stream's temperature rising section is H. up The sodium stream enters the cooling descending channel 2 through the upper connecting channel 3. After releasing heat Q' within the cooling descending channel 2, the sodium stream enters the lower connecting channel 4. The cooling height of the sodium stream within the cooling descending channel 2 is H. down .

[0042] According to some embodiments of this disclosure, the measurement module includes an electromagnetic flowmeter 5, which is disposed in the cooling descending channel and is used to measure the flow rate of sodium.

[0043] According to some embodiments of this disclosure, the measurement module includes multiple thermocouples distributed in the core assembly module and the cooling drop channel to measure the temperature of the sodium flow at different locations in the loop, that is, to measure the temperature distribution of the sodium flow.

[0044] According to some optional embodiments of this disclosure, the core assembly module includes an assembly box and fuel rods. Further optionally, the assembly box is a regular polygonal hollow columnar structure, for example, a regular hexagon.

[0045] According to some optional embodiments of this disclosure, multiple fuel rods are arranged in a bundle within an assembly box, wherein each fuel rod is wound with a wire, and metallic sodium flows within a space jointly defined by the assembly box, the fuel rods, and the wire. Further optionally, multiple fuel rods are arranged in an array within the assembly box, with adjacent fuel rods and the wires on the fuel rods not in contact. The sodium flow occurs through gaps between adjacent fuel rods, gaps between wires, gaps between fuel rods and the assembly box, and gaps between the wires and the assembly box, while being subject to frictional resistance from the wires, fuel rods, and other components.

[0046] According to some embodiments of this disclosure, the measuring device also includes a support disposed at the top and bottom of the core assembly module, the support being suitable for fabricating and securing fuel rods.

[0047] Figure 2 This is a flowchart of a method for measuring the sodium flow frictional resistance during natural circulation of a sodium-cooled fast reactor core assembly according to an exemplary embodiment of the present disclosure.

[0048] According to another aspect of the inventive concept of this disclosure, a method for measuring the sodium flow frictional resistance during natural circulation of a sodium-cooled fast reactor core assembly is also provided, such as... Figure 2 As shown, the measurement method includes operations S210 to S230.

[0049] According to some embodiments of this disclosure, operation S210 includes: acquiring the temperature field of metallic sodium in a natural circulation loop and the flow rate of sodium flow.

[0050] According to some embodiments of this disclosure, operation S220 includes: obtaining the gravity field of the sodium flow in the natural circulation loop using the temperature field, obtaining the driving force formed by the gravity difference when the sodium flow flows in the natural circulation loop using the gravity field, and obtaining the flow resistance of the sodium flow through other parts outside the component to be measured in the natural circulation loop using the sodium flow rate.

[0051] According to some embodiments of this disclosure, operation S230 includes: obtaining the frictional resistance of the core assembly module to the sodium flow during natural circulation using the driving force and the flow resistance of other parts.

[0052] In this embodiment, measurements are first taken using thermocouples and electromagnetic flowmeters, including measuring the sodium flow temperature distribution throughout the natural circulation loop within the reactor box. Specifically, this includes measuring the sodium flow temperature distribution within the simulated core assembly experimental section (heating rise section) and the sodium flow temperature distribution within the natural circulation loop pipes, thereby obtaining the sodium flow density distribution throughout the natural circulation loop within the reactor box. Then, the gravity of the sodium flow is integrated along the height of the natural circulation loop to obtain the driving force that drives the sodium flow to circulate naturally along the natural circulation loop within the reactor box, denoted as ΔP. dv When the natural circulation flow is stable, the driving force of the entire natural circulation flow and the resistance of the natural circulation loop to the sodium flow are equal. Once the driving force of the natural circulation loop is obtained, the flow resistance of the natural circulation loop to the sodium flow is also obtained. This natural circulation flow resistance is denoted as ΔP. rt That is, ΔP rt =ΔP dv .

[0053] According to some embodiments of this disclosure, other resistances include local resistance generated by the sodium flow at the inlet and outlet of the core assembly module, frictional resistance generated by the sodium flow through the natural circulation loop pipe section, local resistance generated by the sodium flow through the natural circulation loop pipe section, and magnetic field braking resistance caused by the sodium flow through the electromagnetic flowmeter cutting magnetic field.

[0054] In this embodiment, excluding the sodium flow frictional resistance during natural circulation of the sodium-cooled fast reactor core assembly to be measured and calculated, other resistances encountered by the sodium flow during the flow process are collectively referred to as other resistances. Other resistances mainly include three parts: the first part is the local resistance ΔP generated by the sodium flow through the inlet and outlet of the simulated core assembly's wire rod bundle assembly. la The second part consists of the local resistance and frictional resistance generated by the sodium flow through the natural circulation loop, excluding the experimental section of the simulated core assembly. Specifically, it refers to the local resistance and frictional resistance generated when the sodium flow passes through the pipe connecting the outlet and inlet of the experimental section of the simulated core assembly, forming the natural circulation loop. Depending on the specific natural circulation loop of the simulated core assembly, the sources of this second part of the resistance vary, but generally include: the frictional resistance generated by the sodium flow through the pipe section of the natural circulation loop, ΔP. fd ; and the local resistance ΔP generated by the sodium flow through the natural circulation loop pipe section. ld For example, the local resistance generated at bends, tees, bellows shut-off valves, and pipe inlets / outlets in the natural circulation loop pipeline section; the third part is the magnetic braking resistance caused by the cutting magnetic field of the electromagnetic flowmeter, ΔP. m .

[0055] Based on this, the resistance to natural circulation flow can be expressed as:

[0056] ΔP rt =ΔP fa +ΔP la +ΔP fd +ΔP ld +ΔP m (0-1).

[0057] The volumetric flow rate of sodium flowing through each part of the natural circulation loop is measured by an electromagnetic flowmeter. The local resistance and frictional resistance generated by the sodium flow in the natural circulation loop pipe section, the inlet and outlet of the simulated core assembly are calculated, i.e., ΔP in formula (0-1). la ΔP fd ΔP ld and ΔP m The resistance to be measured can then be obtained from formula (0-1), which is the frictional resistance of the wire rod bundle assembly to the sodium flow during natural circulation, including:

[0058] ΔP fa =ΔP rt-ΔP la -ΔP fd -ΔP ld -ΔP m (0-2).

[0059] The natural circulation driving force ΔP was calculated by measuring the temperature field of the natural circulation loop in the simulated reactor core assembly. dv Then ΔP dv =ΔP rt Substituting into formula (0-2), we get:

[0060] ΔP fa =ΔP dv -ΔP la -ΔP fd -ΔP ld -ΔP m (0-3).

[0061] According to some embodiments of this disclosure, in operation S220, the gravity field of the sodium flow in the natural circulation loop is obtained using the temperature field, and the driving force formed by the gravity difference during the natural circulation of the sodium flow is obtained using the gravity field, including:

[0062]

[0063] Where, ΔP dv Let ρ(T) be the driving force of the sodium flow in its natural circulation, g be the gravitational acceleration, and H be the height of the sodium flow's natural circulation loop.

[0064] The natural circulation is divided into an absorption rising section and a cooling descending section. Formula (2) is obtained using formula (1):

[0065]

[0066] Among them, H o H is the lowest point of the natural cycle loop. T It is the highest point of the natural cycle loop.

[0067] The density of the sodium flow at different locations is obtained by utilizing the temperatures of the sodium flow in the endothermic rising section and the cooling falling section, including:

[0068] ρ(T)=950.076-0.22976T-1.46049×10- 5 T 2 +5.63788×10 -9 T 3 (3)

[0069] Where T is the sodium flow temperature.

[0070] According to some optional embodiments of this disclosure, ΔPdv The unit is Pa, and the unit of ρ(T) is kg / m³. 3 g is the acceleration due to gravity, taken as 9.8 m / s². 2 .

[0071] According to some embodiments of this disclosure, the local resistance generated by the sodium flow at the inlet and outlet of the core assembly module is obtained by utilizing the sodium flow rate, including sub-operation S221 and sub-operation S222.

[0072] According to some embodiments of this disclosure, sub-operation S221 includes: obtaining the drag coefficients ζ at the inlet and outlet of the core assembly module through numerical simulation or experimental measurement. la，i ζ la，o .

[0073] In this embodiment, the inlet and outlet structures of the core assembly module are complex, with significant variations in the flow direction and cross-section of the sodium flow, resulting in complex sodium flow. There are no empirical formulas to calculate the local resistance of such geometries, making it difficult to accurately determine the local resistance pressure drop. To accurately calculate the local resistance pressure drop at the inlet and outlet of the simulated core assembly, numerical simulation is generally required. The simulated local resistance pressure drop is then used as the local resistance pressure drop generated by the sodium flow at the inlet and outlet of the simulated core assembly. Alternatively, after the simulated core assembly is manufactured, the local resistance at its inlet and outlet is measured, and the experimentally measured local resistance pressure drop is used as the local resistance pressure drop of the sodium flow at the inlet and outlet of the simulated core assembly.

[0074] According to some embodiments of this disclosure, sub-operation S221 includes: calculating the local resistance generated by the sodium flow at the inlet and outlet of the core assembly module using the drag coefficient, including:

[0075]

[0076] Where ρ is the density of the sodium flow through the component, and u is the velocity of the sodium flow through the component.

[0077] According to some embodiments of this disclosure, the magnetic field braking resistance caused by the cutting magnetic field of the sodium flow through the electromagnetic flowmeter is obtained by utilizing the sodium flow rate.

[0078]

[0079]

[0080] Where, ΔP m Where L is the electromagnetic resistance, C is the length of the electromagnetic flowmeter magnet in the flow direction, and L is the electromagnetic resistance. w σ is the reluctance coefficient. f σ wHere, represents the conductivity of the sodium flow and the intermediate measuring tube of the electromagnetic flowmeter magnet, respectively; B is the strength of the electromagnetic flowmeter magnet; and d is the conductivity of the sodium flow and the intermediate measuring tube of the electromagnetic flowmeter magnet. o d i These are the outer and inner diameters of the measuring tube, respectively, and v is the velocity of the sodium flow passing through the measuring tube of the electromagnetic flowmeter.

[0081] In this embodiment, when sodium flows through an electromagnetic flowmeter, the magnetic field lines of the magnetic field cut by the metal generate an induced electromotive force (EMF). The flow velocity of the sodium is measured by measuring this induced EMF. Unlike other fluids, sodium is a liquid metal with good conductivity. Therefore, the induced EMF generates a large induced current. This induced current produces a magnetic force in the magnetic field that is opposite to the direction of sodium flow, hindering the flow of sodium and manifesting as resistance to the sodium flow.

[0082] According to some embodiments of this disclosure, the second part of the other resistance, namely the frictional resistance ΔP generated by the sodium flow through the natural circulation loop pipe section, is... fd The calculation, and the local resistance ΔP generated by the sodium flow through the natural circulation loop pipe section. ld The calculation can be performed using relevant empirical formulas, such as those from fluid mechanics or design manuals. These will not be elaborated upon here, as those skilled in the art have the ability and experience to implement, calculate, and reproduce the calculations.

[0083] The embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. It should be noted that implementations not illustrated or described in the drawings or the main text of the specification are forms known to those skilled in the art and have not been described in detail. Furthermore, the definitions of the various components described above are not limited to the specific structures, shapes, or methods mentioned in the embodiments, and those skilled in the art can easily modify or substitute them.

[0084] It should also be noted that, in the specific embodiments of this disclosure, unless otherwise stated otherwise, the numerical parameters in this specification and the appended claims are approximate values ​​and can be changed according to the desired characteristics obtained from the content of this disclosure. Specifically, all numbers used in the specification and claims to indicate dimensions, range conditions, etc., of the composition should be understood to be modified by the term "about" in all cases. Generally, this means that there may be variations of ±10% in some embodiments, ±5% in some embodiments, ±1% in some embodiments, and ±0.5% in some embodiments.

[0085] Those skilled in the art will understand that the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.

[0086] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A measuring device for measuring the sodium flow frictional resistance during natural circulation of a sodium-cooled fast reactor core assembly, comprising: The core assembly module includes filament-wound fuel rods and liquid sodium flowing around the filament-wound fuel rods; The cooling descending channel is suitable for cooling the sodium flow within the channel, and its two ends are respectively connected to the two ends of the wound fuel rod; A heating module is suitable for heating the core assembly module to enable the liquid sodium to form a natural circulation loop within the core assembly module, the connecting channel, and the cooling descent channel; The measurement module is suitable for measuring the temperature distribution and flow rate of metallic sodium in a natural circulation loop; as well as The calculation module is suitable for calculating the frictional resistance of sodium flow within the core assembly module based on the temperature distribution and the flow rate.

2. The measuring device according to claim 1, wherein, The measurement module includes: An electromagnetic flowmeter is installed in the cooling drop channel to measure the flow rate of sodium.

3. The measuring device according to claim 1, wherein, The measurement module includes multiple thermocouples distributed in the core assembly module and the cooling drop channel to measure the temperature distribution of the sodium flow.

4. The measuring device according to claim 1, wherein, The core assembly module includes: Component box; and Multiple fuel rods are arranged in the component box to form a rod bundle, wherein each fuel rod is wound with a wire, and the metallic sodium flows within the space defined by the component box, the fuel rods and the wire.

5. The measuring device according to claim 1, wherein, The measuring device further includes: Supports are provided at the top and bottom of the core assembly module, and the supports are adapted to form and secure the fuel rods.

6. A method for measuring the sodium flow frictional resistance during natural circulation of a sodium-cooled fast reactor core assembly, comprising: Obtain the temperature field and sodium flow rate of metallic sodium in a natural circulation loop; The temperature field is used to obtain the gravitational field of the sodium flow in the natural circulation loop. The gravitational field is used to obtain the driving force formed by the gravity difference when the sodium flow flows in the natural circulation loop. The flow rate of the sodium flow is used to obtain other resistances of the sodium flow. as well as The frictional resistance of the core assembly module to the sodium flow during natural circulation is obtained using the driving force and the other resistances.

7. The measurement method according to claim 6, wherein, The other resistances include the local resistance generated by the sodium flow at the inlet and outlet of the core assembly module, the frictional resistance generated by the sodium flow through the natural circulation loop pipe section, the local resistance generated by the sodium flow through the natural circulation loop pipe section, and the magnetic field braking resistance caused by the sodium flow through the electromagnetic flowmeter cutting magnetic field.

8. The measurement method according to claim 6, wherein, The gravitational field of the sodium flow in the natural circulation loop is obtained using the temperature field, and the driving force formed by the gravity difference during the natural circulation flow of the sodium flow is obtained using the gravitational field, including: ΔP dv =∮ρ(T)gdH (1) Wherein, ΔP dv ρ(T) is the driving force of the sodium flow in natural circulation, g is the gravitational acceleration, and H is the height of the sodium flow natural circulation loop. The natural circulation is divided into an absorption rising section and a cooling descending section. Formula (2) is obtained using formula (1): Among them, H o H is the lowest point of the natural cycle loop. T It is the highest point of the natural cycle loop; The density of the sodium flow at different locations is obtained by utilizing the temperatures of the sodium flow in the endothermic rising section and the cooling falling section, including: ρ(T)=950.076-0.22976T-1.46049×10 -5 T 2 +5.63788×10 -9 T 3 (3) Where T is the sodium flow temperature.

9. The measurement method according to claim 7, wherein, The local resistance generated by the sodium flow at the inlet and outlet of the core assembly module, obtained using the sodium flow rate, includes: The drag coefficients ζ at the inlet and outlet of the core assembly module are obtained through numerical simulation or experimental measurement. la,i ζ la,o ; The local resistance generated by sodium flow at the inlet and outlet of the core assembly module is calculated using the aforementioned drag coefficient, including: Where ρ is the density of the sodium flow through the component, and v is the velocity of the sodium flow through the component.

10. The measurement method according to claim 7, wherein, The magnetic braking resistance caused by the cutting magnetic field of the sodium flow through the electromagnetic flowmeter, obtained using the sodium flow rate, includes: Wherein, ΔP m Where L is the electromagnetic resistance, C is the length of the electromagnetic flowmeter magnet in the flow direction, and L is the electromagnetic resistance. w σ is the reluctance coefficient. f σ w Here, represents the conductivity of the sodium flow and the intermediate measuring tube of the electromagnetic flowmeter magnet, respectively; B is the strength of the electromagnetic flowmeter magnet; and d is the conductivity of the sodium flow and the intermediate measuring tube of the electromagnetic flowmeter magnet. o d i These are the outer and inner diameters of the measuring tube, respectively, and v is the velocity of the sodium flow passing through the measuring tube of the electromagnetic flowmeter.

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