A cross-dimensional coupling analysis method for containment and pressure suppression systems

Abstract

This invention discloses a cross-dimensional coupled analysis method for containment and pressure suppression systems, comprising the following steps: 1. Geometric modeling, node and mesh generation, and initialization of the containment and pressure suppression system; 2. Calculation of the thermal-hydraulic state of the internal compartments of the containment using a multi-node containment analysis program; 3. Calculation of the thermal-hydraulic state of the pressure suppression system using three-dimensional computational fluid dynamics software; 4. Calculation of the flow velocities of steam and non-condensable gases at the inlet of the pressure suppression pipe; 5. Repeating steps 2 to 4 until a specified calculation time is reached. This method can accurately calculate the pressure and temperature response of the pressure suppression system and its impact on the thermal-hydraulic state of the containment, which is of great significance for containment integrity analysis.

Description

Technical Field

[0001] This invention belongs to the field of nuclear reactor containment accident phenomenon calculation technology, specifically involving a cross-dimensional coupling analysis method for containment and suppression system. Background Technology

[0002] Small reactors are constrained by the space within the containment vessel, and the internal pressure rises rapidly during a LOCA (Local Occurrence of Accidents) accident. A pressure-suppressed containment can introduce high-temperature, high-pressure gases into a water pool via pressure-suppressing pipes, allowing heat to be dissipated through direct contact condensation, thereby suppressing the increase in internal pressure.

[0003] Currently, one-dimensional system analysis programs such as GOTHIC, RELAP5, and ATHROC are widely used for calculating the thermal-hydraulic state of compartments within containment systems. However, pressure suppression systems involve complex thermal-hydraulic phenomena, including jet flow and bubble dynamics, which one-dimensional system analysis programs cannot accurately predict. Furthermore, the pressure suppression system and the containment system interact with each other, and there is currently no good method to comprehensively calculate the thermal-hydraulic behavior of the containment system, the pressure suppression system, and the containment system under pressure suppression. Summary of the Invention

[0004] To fill the research gaps in the existing technologies, this invention provides a cross-dimensional coupling analysis method for containment and pressure suppression systems. This method can quickly and accurately calculate the pressure suppression effect of the pressure suppression system in nuclear power plant accidents and its impact on the thermal-hydraulic state inside the containment during the accident. This method is of great significance for the calculation of nuclear reactor containment accident phenomena.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for cross-dimensional coupling analysis of containment and pressure suppression systems includes the following steps:

[0007] Step 1: Perform geometric modeling and node / mesh generation for the containment and pressure suppression system, and initialize them;

[0008] Step 1-1: Geometric modeling and node / mesh generation of the containment and pressure suppression system:

[0009] The pressure-suppressed containment consists of a containment and a pressure-suppressing system. A multi-node containment analysis program is used to perform geometric modeling and node generation of the containment; Geometry software in Ansys Workbench is used to perform geometric modeling of the pressure-suppressing system; and Mesh software in Ansys Workbench is used to perform mesh generation of the geometric model of the pressure-suppressing system.

[0010] Steps 1-2: Initialize the thermo-hydraulic state of the internal compartments and pressure suppression system of the containment;

[0011] Step 2: Multi-node containment analysis program with t n Temperature of each compartment inside the containment at all times pressure Steam share and the steam flow rate at the inlet of the pressure suppressor pipe non-condensable gas flow rate As a boundary condition, calculate t n+1 Temperature of each compartment inside the containment at all times pressure Steam share Temperature at the node where the pressure suppressor inlet is located pressure density and steam share

[0012] Step 3: Use the computational fluid dynamics software Fluent with t n Temperature of the air space of the constant pressure suppression system pressure and steam share Temperature of water space Steam velocity at the inlet of the pressure suppressor non-condensable gas flow rate As a boundary condition, calculate the pressure suppression system t n+1 Temperature of the air space at all times pressure and steam share Temperature of water space Suppression tube inlet pressure temperature density and steam share

[0013] Step 4: Calculate t n+1 The gas flow rate at the inlet of the constant pressure suppression tube;

[0014] Step 4-1: Calculate t n+1 The total gas flow rate w at the inlet of the pressure suppressor tube at any given time n+1 :

[0015]

[0016] In the formula:

[0017] Z j,d —Node elevation inside the containment at the pressure suppressor inlet;

[0018] Z j,r —Elevation of the pressure suppression system node at the pressure suppression pipe inlet;

[0019] g — acceleration due to gravity;

[0020] Step 4-2: Calculate t n+1 Steam flow rate at the inlet of the pressure suppressor pipe non-condensable gas flow rate

[0021]

[0022] Step 5: t n+1 Time as a new t n At time t, repeat steps 2 through 4 until a new t is reached. n The specified calculation time is reached at any given moment.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. The multi-node containment analysis program and the computational fluid dynamics software Fluent are coupled for calculation. The multi-node containment analysis program is used to calculate the thermal-hydraulic behavior inside large containments. It is fast and requires less computational resources. For pressure suppression systems with complex geometry and involving jet and bubble dynamics, the computational fluid dynamics software Fluent is used for three-dimensional calculation, which is highly accurate.

[0025] 2. The computational fluid dynamics software Fluent can accurately simulate the operating state of the pressure suppression system, including the simulation of jet phenomena, bubble dynamics, and gas-liquid phase transition phenomena at the pressure suppression pipe outlet;

[0026] 3. Since the multi-node containment analysis program used in this invention can calculate the thermal-hydraulic state inside the containment, and the Fluent program can calculate the thermal-hydraulic state of the pressure suppression system, and the coupled calculation between the two is achieved by calculating the gas flow velocity at the inlet of the pressure suppression pipe, the method of this invention can analyze the thermal-hydraulic behavior inside the containment, the temperature and pressure response process of the pressure suppression system, and the interaction process between the containment and the pressure suppression system during an accident.

[0027] 4. The computational fluid dynamics software Fluent and the one-dimensional containment analysis program are relatively independent and can be calculated separately, which facilitates the further development of the coupled program later. Attached Figure Description

[0028] Figure 1 A flowchart of a cross-dimensional coupling analysis method for containment and pressure suppression systems;

[0029] Figure 2 This is a schematic diagram of a pressure-suppressing containment structure.

[0030] Figure 3 A schematic diagram showing the division of internal compartment nodes within the containment structure;

[0031] Figure 4 The diagram shows the modeling and mesh generation of the suppression system, where (a) is the geometric modeling of the suppression system and (b) is the mesh generation of the suppression system. Detailed Implementation

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

[0033] like Figure 1 As shown, this invention provides a cross-dimensional coupling analysis method for containment and pressure suppression systems, including the following:

[0034] Step 1: Perform geometric modeling and node / mesh generation for the containment and pressure suppression system, and initialize them;

[0035] Step 1-1: Geometric modeling and node / mesh generation of the containment and pressure suppression system:

[0036] according to Figure 2 A schematic diagram of a pressure-suppressed containment. The pressure-suppressed containment consists of a containment and a pressure-suppressing system. A multi-node containment analysis program is used to perform geometric modeling and node generation of the containment. Geometry software in Ansys Workbench is used to perform geometric modeling of the pressure-suppressing system, and Mesh software in Ansys Workbench is used to perform mesh generation of the geometric model of the pressure-suppressing system.

[0037] A schematic diagram of the containment node division is shown below. Figure 3 As shown, the axial direction is divided into 9 layers, the circumferential direction into 2 layers, and the outer layer is divided into 4 nodes at different angles along the circumferential direction, for a total of 45 nodes;

[0038] Geometric modeling of the suppression system is performed in the Geometry software within Ansys Workbench, such as... Figure 4 As shown in (a), it includes a pressure-suppressing tube, an air space, and a water space;

[0039] The geometric model of the suppression system was imported into the Mesh software in Ansys Workbench for mesh generation: "Physical Preference" was set to "CFD", "Solver Preference" to "Fluent", and "Element Order" to "Linear"; the meshing result is as follows. Figure 4 As shown in (b), a total of 666,442 nodes and 642,382 units are divided.

[0040] Import the meshed suppression system model into the fluid dynamics software Fluent;

[0041] Steps 1-2: Initialize the thermo-hydraulic state of the internal compartments and pressure suppression system of the containment;

[0042] Initialize the thermo-hydraulic state of the containment interior and the pressure suppression system, including the temperature T at each node inside the containment. i_c0 Pressure P i_c0 and steam share α i_st_c0 The air space temperature T of the pressure suppression system g0 Pressure P g0 and gaseous component α st_g0 The temperature M of the water space in the pressure suppression system w0 ;

[0043] Step 2: Multi-node containment analysis program with t n Temperature of each compartment inside the containment at all times pressure Steam share and the steam flow rate at the inlet of the pressure suppressor pipe non-condensable gas flow rate t is calculated as a boundary condition. n+1 Temperature of each compartment inside the containment at all times pressure Steam share Temperature at the node where the pressure suppressor inlet is located pressure density and steam share

[0044] Step 3: Use the computational fluid dynamics software Fluent with t n Temperature of the air space of the constant pressure suppression system pressure and steam share Temperature of water space Steam velocity at the inlet of the pressure suppressor non-condensable gas flow rate As boundary condition calculation, the suppression system t n+1 Temperature of the air space at all times pressure and gas components Temperature of water space Suppression tube inlet pressure temperature density and steam share

[0045] Step 4: Calculate t n+1 The gas flow rate at the inlet of the constant pressure suppression tube;

[0046] Step 4-1: Calculate t n+1 The total gas flow rate w at the inlet of the pressure suppressor tube at any given time n+1 :

[0047]

[0048] In the formula,

[0049] Z j,d —Node elevation inside the containment at the pressure suppressor inlet;

[0050] Z j,r —Elevation of the pressure suppression system node at the pressure suppression pipe inlet;

[0051] g — acceleration due to gravity;

[0052] Step 4-2: Calculate t n+1 Steam flow rate at the inlet of the pressure suppressor pipe non-condensable gas flow rate

[0053] Step 5: t n+1 Time as a new t n At time t, repeat steps 2 through 4 until a new t is reached. n The specified calculation time is reached at any given moment.

[0054] The above description is a further detailed explanation of the present invention in conjunction with specific preferred embodiments. It should not be considered that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the scope of patent protection determined by the submitted claims.

Claims

1. A cross-dimensional coupling analysis method for containment and pressure suppression systems, characterized in that: Includes the following steps: Step 1: Perform geometric modeling and node / mesh generation for the containment and pressure suppression system, and initialize them; Step 1-1: Geometric modeling and node / mesh generation of the containment and pressure suppression system: The pressure-suppressed containment consists of a containment and a pressure-suppressing system. A multi-node containment analysis program is used to perform geometric modeling and node generation of the containment; Geometry software in Ansys Workbench is used to perform geometric modeling of the pressure-suppressing system; and Mesh software in Ansys Workbench is used to perform mesh generation of the geometric model of the pressure-suppressing system. Steps 1-2: Initialize the thermo-hydraulic state of the internal compartments and pressure suppression system of the containment; Step 2: Multi-node containment analysis program with t n Temperature of each compartment inside the containment at all times pressure Steam share and the steam flow rate at the inlet of the pressure suppressor pipe non-condensable gas flow rate As a boundary condition, calculate t n+1 Temperature of each compartment inside the containment at all times pressure Steam share Temperature at the node where the pressure suppressor inlet is located pressure density and steam share Step 3: Use the computational fluid dynamics software Fluent with t n Temperature of the air space of the constant pressure suppression system pressure and steam share Temperature of water space Steam velocity at the inlet of the pressure suppressor non-condensable gas flow rate As a boundary condition, calculate the pressure suppression system t n+1 Temperature of the air space at all times pressure and steam share Temperature of water space Suppression tube inlet pressure temperature density and steam share Step 4: Calculate t n+1 The gas flow rate at the inlet of the constant pressure suppression tube; Step 4-1: Calculate t n+1 The total gas flow rate w at the inlet of the pressure suppressor tube at any given time n+1 : In the formula: Z j,d —Node elevation inside the containment at the pressure suppressor inlet; Z j,r —Elevation of the pressure suppression system node at the pressure suppression pipe inlet; g — acceleration due to gravity; Step 4-2: Calculate t n+1 Steam flow rate at the inlet of the pressure suppressor pipe non-condensable gas flow rate Step 5: t n+1 Time as a new t n At time t, repeat steps 2 through 4 until a new t is reached. n The specified calculation time is reached at any given moment.

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