Dose rate analysis method

Abstract

The invention relates to a dose rate analysis method, which is applied to a regenerative heat exchanger of a chemical capacity system in a pressurized water reactor unit, and comprises the following steps: S1, generating a three-dimensional geometric model corresponding to the heat exchanger based on a CFD platform; s2, acquiring a source item nuclide corresponding to the pressurized water reactor unit, and establishing a form transformation mechanism model corresponding to the source item nuclide; s3, acquiring a target working condition corresponding to the pressurized water reactor unit, and setting a boundary condition and an initial condition of the three-dimensional geometric model; s4, performing grid division on the three-dimensional geometric model, and obtaining a nuclide deposition rate of the morphological transformation mechanism model according to the obtained grid to select a target grid; and S5, an MCNP model corresponding to the three-dimensional geometric model is established, and the dose rate of the preset part of the heat exchanger is obtained according to the MCNP model, the target grid and the form transformation mechanism model. By implementing the method, the dose rate field distribution in the heat exchanger can be accurately obtained, and the method is of great significance to safe and economical operation of a nuclear power unit.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear power, more particularly, to a dose rate analysis method. BACKGROUND

[0002] During the operation and overhaul of the unit, a large amount of activated corrosion products in the reactor core and the steam generator will enter the main pipeline and migrate and deposit in other systems. The corrosion of the structural materials in the primary loop system of the pressurized water reactor under high temperature and high pressure conditions not only affects the safety of the reactor, but also causes the corrosion products to migrate in the primary loop system with the coolant, which further causes the activated reaction of the corrosion products under the irradiation of the neutron field in the core, and then generates radionuclides. The radiation field generated by the deposition of these radionuclides in the primary loop is the main source of personal dose of the maintenance personnel during the overhaul of the pressurized water reactor.

[0003] The chemical and volume control system (RCV) of the pressurized water reactor unit plays a key role in dealing with corrosion products, and maintains the water quality in the primary loop through a series of functions, reduces the corrosion risk and ensures the safe and stable operation of the reactor. The regenerative heat exchanger (RCV001EX) plays a key role in the chemical and volume control system of the pressurized water reactor unit, which is mainly used for recovering and utilizing the heat of the coolant, and realizing the temperature regulation and energy optimization of the fluid. Due to the complex effects of fluid mechanics and thermophysical effects, there are more corrosion product deposits and higher dose rate in the regenerative heat exchanger. Specifically:

[0004] Main flow transport: the corrosion products carried by the discharge flow enter the heat exchanger at a flow rate of 2-5 m / s, and the inertial motion of the particles tends to hit the surface of the tube bundle.

[0005] Turbulent diffusion: in the shell side of the shell-and-tube heat exchanger, the turbulent flow caused by the baffle intensifies the lateral mixing of the particles, which promotes their migration to the tube wall.

[0006] Secondary flow effect: the centrifugal force at the U-shaped tube bend causes the fluid to stratify, and the high-density particles gather to the outer tube wall, forming a local deposition hot spot.

[0007] Temperature gradient induction: under high temperature, the dissolved metal ions (such as Fe 2+ ) are precipitated to form Fe3O4 particles when flowing through the tube bundle with lower temperature due to the decrease of solubility.

[0008] Thermal migration phenomenon: the particles migrate to the low-temperature area under the action of temperature gradient, which causes the increase of the deposition amount at the low-temperature side of the tube bundle (such as the inlet end of the cooling water).

[0009] Traditional dose rate analysis is rough, especially for the source term distribution in the equipment under the conditions of geometric structure and flow heat exchange, and there is no effective analysis method, which is often approximate estimation and lacks systematic mechanism analysis. Accurate calculation of the deposition amount of activated corrosion products of the regenerative heat exchanger and prediction of its dose field are of great significance to the safe operation of the unit, reduction of collective dose and improvement of radiation safety. SUMMARY

[0010] The technical problem solved by the present application is to provide a dose rate analysis method to solve the above technical defects of the prior art.

[0011] The technical solution adopted by the present application to solve its technical problem is: a dose rate analysis method is constructed and applied to a regenerative heat exchanger of a containment system in a pressurized water reactor unit, comprising the following steps:

[0012] S1, generating a three-dimensional geometric model corresponding to the heat exchanger based on a CFD platform;

[0013] S2, obtaining source term nuclides corresponding to the pressurized water reactor unit, and establishing a morphological conversion mechanism model corresponding to the source term nuclides;

[0014] S3, obtaining a target working condition corresponding to the pressurized water reactor unit, and setting boundary conditions and initial conditions of the three-dimensional geometric model;

[0015] S4, meshing the three-dimensional geometric model to obtain a target mesh according to the nuclide deposition rate of the morphological conversion mechanism model;

[0016] S5, establishing an MCNP model corresponding to the three-dimensional geometric model to obtain the dose rate of a predetermined part of the heat exchanger according to the MCNP model, the target mesh and the morphological conversion mechanism model.

[0017] Preferably, in an embodiment of the dose rate analysis method of the present application, in the step S1, the three-dimensional geometric model corresponding to the heat exchanger is generated based on the CFD platform; comprising:

[0018] The three-dimensional geometric model is established according to the length of the pipe section, the pipe diameter, the number of pipes, the bend curvature radius and the baffle arrangement of the heat exchanger.

[0019] Preferably, in an embodiment of the dose rate analysis method of the present application, the morphological conversion mechanism model corresponding to the source term nuclides comprises the deposition rate of the dissolved corrosion products corresponding to the source term nuclides into particulate matter, the deposition rate and erosion rate of the particulate corrosion products; in the step S2, the morphological conversion mechanism model corresponding to the source term nuclides is established; comprising:

[0020] obtaining a deposition rate of the source term nuclide corresponding to the dissolved corrosion product into the particulate matter, a deposition rate of the particulate corrosion product, and an erosion rate.

[0021] Preferably, in the embodiment of the dose rate analysis method of the present application, the method further comprises:

[0022] obtaining a deposition rate of the source term nuclide corresponding to the dissolved corrosion product into the particulate matter according to the following formula,

[0023]

[0024] wherein, P w is the wet perimeter, C bulk (T) is the concentration of the dissolved corrosion product at the main coolant temperature T, C sat (T) is the saturation concentration of the dissolved corrosion product at the near-wall coolant temperature T, and K SD is the mass transfer coefficient.

[0025] Preferably, in the embodiment of the dose rate analysis method of the present application, the method further comprises:

[0026] obtaining a deposition rate of the particulate corrosion product corresponding to the source term nuclide according to the following formula,

[0027]

[0028] wherein, K PD is the mass transfer coefficient of the particulate corrosion product, C p,bulk (T) is the concentration of the particulate matter at the main coolant temperature T, C p,wall (T) is the concentration of the particulate matter at the near-wall coolant temperature T.

[0029] Preferably, in the embodiment of the dose rate analysis method of the present application, the method further comprises: obtaining an erosion rate corresponding to the source term nuclide according to the following formula,

[0030]

[0031] wherein, ε is the erosion constant, τ is the shear stress, W a is the work deposited to the surface layer, E tot is the total adhesion energy, and d is the thickness of the deposit.

[0032] Preferably, in the embodiment of the dose rate analysis method of the present application, in the step S5, the establishing of the MCNP model corresponding to the three-dimensional geometric model comprises:

[0033] generating a cell model of the MCNP model based on the materials, densities, and geometric ranges corresponding to different regions in the heat exchanger;

[0034] generating a surface card model of the MCNP model based on the surface morphology in the heat exchanger structure;

[0035] generating a data card model of the MCNP model based on the working parameters in the heat exchanger.

[0036] Preferably, in an embodiment of the dose rate analysis method of the present application, the data card model of the MCNP model comprises:

[0037] a mode card for specifying the particle type of the simulation;

[0038] a material card for defining the source term nuclide;

[0039] a source definition card for defining the characteristics of the particle source corresponding to the source term nuclide;

[0040] an energy and conversion factor card for defining the energy grouping and corresponding physical quantity conversion factors;

[0041] a detector card for defining the physical quantity to be calculated and the detection position.

[0042] Preferably, in an embodiment of the dose rate analysis method of the present application, in the step S2,

[0043] the target working conditions corresponding to the pressurized water reactor unit include: power operation conditions of the pressurized water reactor unit, and / or transient conditions of the pressurized water reactor unit at different pressure / temperature platforms in the overhaul stage; and / or

[0044] the setting of the boundary conditions of the three-dimensional geometric model includes setting the boundary conditions and initial conditions of the inlets and outlets of the downflow and upflow.

[0045] Preferably, in an embodiment of the dose rate analysis method of the present application, in the step S4, the three-dimensional geometric model is meshed to obtain a target mesh according to the nuclide deposition rate of the morphology conversion mechanism model obtained by the meshing; comprising:

[0046] based on the structured grid, the morphology conversion mechanism model corresponding to the source term nuclide is calculated by local adjustment of the structured grid to obtain a steady state, and the target mesh is determined based on the steady state calculation result.

[0047] The dose rate analysis method of the present application has the following beneficial effects: the dose rate field distribution in the heat exchanger can be accurately obtained, which is of great significance to the safe and economic operation of the nuclear power unit. BRIEF DESCRIPTION OF DRAWINGS

[0048] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0049] Figure 1 is a program flow chart of a dose rate analysis method of the present application. DETAILED DESCRIPTION

[0050] In order to have a clearer understanding of the technical features, objectives and effects of the present application, the specific embodiments of the present application will be described in detail with reference to the accompanying drawings.

[0051] As shown in Figure 1 , an embodiment of a dose rate analysis method of the present application is shown. The method is mainly used for the regenerative heat exchanger of the containment system in a pressurized water reactor unit, that is, for realizing the dose rate analysis in the regenerative heat exchanger of the containment system in a pressurized water reactor unit. Figure 1 In the embodiment of the dose rate analysis method of the present application shown, the following steps are included: S1, generating a three-dimensional geometric model corresponding to the heat exchanger based on a CFD platform; S2, obtaining source item nuclides corresponding to the pressurized water reactor unit, and establishing a morphological conversion mechanism model corresponding to the source item nuclides; S3, obtaining a target working condition corresponding to the pressurized water reactor unit, and setting boundary conditions and initial conditions of the three-dimensional geometric model; S4, performing grid division on the three-dimensional geometric model, so as to select a target grid according to the obtained grid and the nuclide deposition rate of the morphological conversion mechanism model; S5, establishing an MCNP model corresponding to the three-dimensional geometric model, so as to obtain a dose rate of a preset part of the heat exchanger according to the MCNP model, the target grid and the morphological conversion mechanism model.

[0052] In step S1, taking the RCV001EX heat exchanger in the nuclear power unit as an example. Among them, RCV001EX is a shell and tube heat exchanger, and the inlet at the upper part of the shell side is the downflow from the cold pipe section of the unit, which is fully heat exchanged with the lower temperature upper flow on the tube side through the baffle plate arranged on the shell side. In the shell side flow process, in order to increase the stirring action, more baffle plates are arranged, which will cause the local flow rate change of the downflow carrying more corrosion deposition products, and will promote the deposition of corrosion products in the area near the baffle plate. The tube bundle on the tube side has 178 tubes, and the upper flow in the tube is the upper flow with lower pressure and temperature. There are more corrosion products in the downflow, and fewer corrosion products in the upper flow. In the complex flow and heat exchange process of the shell side and the tube side, the ionic corrosion products in the coolant will precipitate into particulate corrosion products in the coolant as the local solubility decreases, and the particulate corrosion products in the coolant will accumulate and grow, and finally deposit on the deposition layer of the shell side and the tube wall. On the contrary, the corrosion products on the deposition layer become particulate and enter the coolant under the erosion of the coolant, and the particulate corrosion products will be converted into ionic corrosion products as the local solubility changes. First, the shell side and tube side fluid domains of RCV001EX can be modeled three-dimensionally. In the specific process, a complete geometric model can be established according to the design drawings of the corresponding nuclear power unit.

[0053] Based on step S2, a porous medium model and a turbulence model can be selected based on the CFD platform to generate a corrosion product conversion mechanism model, which is coupled and solved after being embedded in the CFD platform. That is, according to the mass flow of one or more source terms of the unit design, based on the mechanism of the precipitation of ionic corrosion products into particulate corrosion products and the dissolution of particulate corrosion products into ionic corrosion products, a form conversion mechanism model corresponding to the source term is established. Among them, the source term of the nuclear power plant is the form, quantity, and other release characteristics of the radioactive substances released into the environment by the nuclear power plant during normal operation or in the event of an accident. The source term of the radioactive nuclide of the nuclear power plant is the characterization of the radioactive substances generated and discharged by the nuclear power plant; including the type, form, activity concentration and total amount of radioactive nuclides. For example, the particulate Fe3O4 is selected, and the corresponding dissolved ion Fe 3+ .

[0054] Based on step S3, according to the working characteristics of the pressurized water reactor unit, the target working condition corresponding to the pressurized water reactor unit is set, so that the pressurized water reactor unit is analyzed according to the target working condition. At the same time, the boundary conditions and initial conditions of the three-dimensional geometric model obtained above are set. The simulation process is limited to the actual working state of the heat exchanger.

[0055] In an embodiment, the power operation conditions of the PWR unit, and / or the transient operation conditions of the PWR unit at different pressure / temperature platforms in the overhaul stage. That is, the calculation and analysis can be performed based on multiple working states of the nuclear power unit, so that the calculation results can consider the influence of different working conditions of the nuclear power unit as much as possible.

[0056] In an embodiment, the setting of the boundary conditions of the three-dimensional geometric model includes setting the boundary conditions of the inlets and outlets of the underflow and the upflow. The CFD platform has a plurality of existing porous medium models for the tube side and the shell side respectively, and the corresponding porosity, pressure drop and other parameters are set.

[0057] Based on step S4, in computational fluid dynamics (CFD), the core purpose of the grid is to discretize the continuous physical space into a finite number of calculable units, so as to realize the numerical solution of the fluid motion equation. The grid divides the complex fluid domain into small units (such as tetrahedron, hexahedron, etc.), each unit represents an independent solution domain of the partial differential equation, so that the continuous Navier-Stokes equation can be approximately solved by algebraic equations at discrete nodes. In a specific embodiment, the basic feature of CFD is to perform difference on the differential equation group on the grid to obtain a difference equation group. In a specific embodiment, after the model is set and coupled based on a plurality of grids on the CFD platform, the nuclide deposition rate of the plurality of grids is analyzed to verify the grid independence. That is, under the premise of ensuring accuracy and considering the cost of calculation, a suitable grid is selected to obtain the target grid.

[0058] Based on step S5, MCNP (Monte Carlo N-Particle Transport Code) is a tool for calculating the transport of neutrons, photons, electrons or their coupling in a three-dimensional complex geometric structure. The radiation transmission process of the source nuclide in the shielding material of a specific geometric shape can be simulated by constructing an MCNP model, so as to finally obtain the dose rate of the source nuclide at some specific positions of the heat exchanger, for example, at the preset positions. That is, the dose rate analysis of each position in the heat exchanger can be further realized.

[0059] In an embodiment, in the step S1, the three-dimensional geometric model corresponding to the heat exchanger is generated based on the CFD platform; including: establishing the three-dimensional geometric model according to the tube length, tube diameter, tube number, bend curvature radius and baffle arrangement of the heat exchanger. Specifically, when establishing the three-dimensional geometric model of the heat exchanger, the key geometric parameters of the heat exchanger can be obtained, such as the tube length, tube diameter, tube number, bend curvature radius and baffle arrangement of the heat exchanger. In some embodiments, non-key geometric parameters can be ignored, for example, when constructing the three-dimensional geometric model, the fillet structure in the heat exchanger which does not affect the flow characteristics can be removed.

[0060] In an embodiment, the morphology conversion mechanism model corresponding to the source term nuclide includes: deposition rate of dissolved corrosion product into particulate, deposition rate and erosion rate of particulate corrosion product corresponding to the source term nuclide; the step S2 of establishing the morphology conversion mechanism model corresponding to the source term nuclide includes: obtaining the deposition rate of dissolved corrosion product into particulate, deposition rate and erosion rate of particulate corrosion product corresponding to the source term nuclide. Specifically, when the morphology conversion mechanism model corresponding to the source term nuclide is established, the calculation formula related to the deposition rate of dissolved corrosion product into particulate, deposition rate and erosion rate of particulate corrosion product corresponding to the source term nuclide is mainly obtained.

[0061] In an embodiment, the deposition rate of dissolved corrosion product into particulate corresponding to the source term nuclide can be obtained according to the following formula,

[0062]

[0063] Wherein, P w is the wet perimeter, C bulk (T) is the concentration of dissolved corrosion product at the main coolant temperature T, C sat (T) is the saturation concentration of dissolved corrosion product at the near-wall coolant temperature T, K SD is the mass transfer coefficient.

[0064] In an embodiment, the deposition rate of particulate corrosion product corresponding to the source term nuclide can be obtained according to the following formula,

[0065]

[0066] Wherein, K PD is the mass transfer coefficient of particulate corrosion product, C p,bulk (T) is the concentration of particulate at the main coolant temperature T, C p,wall (T) is the concentration of particulate at the near-wall coolant temperature T.

[0067] The size of the particulate in the primary coolant of the water reactor is mostly distributed in the range of molecular radius to 1 μm. For such a size range, it can be considered that the deposition process of the particulate is mainly determined by the mass transfer process controlled by Brownian motion, and the mass transfer mechanism is similar to that of the dissolved corrosion product. A suitable diffusion coefficient is used for calculation. For smaller particulate, the adhesion probability of the particulate on the surface is approximately equal to 1, and the concentration of the particulate near the wall surface is almost 0, so the deposition rate of the particulate corrosion product can be expressed by the above formula.

[0068] In an embodiment, the erosion rate corresponding to the source term nuclide can be obtained according to the following formula,

[0069]

[0070] where ε is the erosion constant, τ is the shear stress, W a is the work deposited to the surface, E tot is the total adhesion energy, d is the deposit thickness.

[0071] Erosion-corrosion refers to the phenomenon of material surface damage caused by the combined action of erosion and corrosion when the solution and the material move at a high speed. After the dissolution and corrosion products and the particle corrosion products are deposited on the surface of the core cladding, a loose and porous deposition layer is formed, and the surface of the deposition layer is eroded under the action of the shear stress generated by the coolant flow, and then decomposed back into the coolant. Generally speaking, the erosion rate of the corrosion product deposition layer by the coolant is proportional to the shear stress caused by the coolant, and therefore, the erosion rate can be obtained by the above formula.

[0072] In an embodiment, in the step S5, the MCNP model corresponding to the three-dimensional geometric model is established, including: generating a cell model of the MCNP model based on the materials, densities and geometric ranges of different regions in the heat exchanger; generating a surface card model of the MCNP model based on the surface morphology in the structure of the heat exchanger; and generating a data card model of the MCNP model based on the working parameters in the heat exchanger. That is, based on the MCNP software (Monte Carlo transport program), a cell card, a surface card and a data card and the like can be written, and the source term (corrosion product distribution) results obtained by CFD analysis can be input into the database, so as to finally obtain a more accurate dose rate model and results.

[0073] In the above formula, different regions (units) in the RCV001EX are defined by the cell model, each unit has a specific material, density and geometric range, and in particular, the baffle cell is set according to the arrangement characteristics of the shell side baffle. The surface card model defines various surfaces of the structure of the RCV001EX, such as plane, cylindrical surface, spherical surface and the like. These surfaces are the basis for constructing the geometric shape of the simulation space, and through the combination of different surfaces, a complex three-dimensional geometric structure can be created. The data card model can specifically include a material card, a mode card, a source definition card, an energy and conversion factor card, a detector card and the like. The mode card is used to specify the particle type of the simulation. The material card defines various materials used in the simulation, and clearly defines the nuclides contained in the material and the atomic density thereof. The source definition card defines the characteristics of the particle source based on the deposition of the corrosion product nuclides obtained by CFD analysis, including the position, energy, emission direction, particle type and the like of the source. The energy and conversion factor card defines the energy grouping and the corresponding physical quantity conversion factor, and the detector card defines the physical quantity to be calculated and the detection position.

[0074] In an embodiment, in the step S4, the three-dimensional geometric model is meshed to obtain a target mesh for a nuclide deposition rate of the morphology conversion mechanism model; including: based on a structured mesh, the structured mesh is adjusted locally to perform a steady-state calculation on the morphology conversion mechanism model corresponding to the source term nuclide, and the target mesh is obtained based on the steady-state calculation result. That is, after mesh selection and summary, based on the preset mesh and model and parameter, non-steady-state or steady-state calculation is carried out, and the deposition rate of the unit power operation and the different pressure and temperature platform transient operation in the overhaul stage is obtained. Finally, the target mesh is obtained.

[0075] In the above embodiment, the RCV001EX dose rate analysis method of the pressurized water reactor unit based on the CFD technology comprehensively considers the influence of the three-dimensional flow field, temperature field and pressure field in the RCV001EX on the migration and deposition of the corrosion activation product; the more accurate corrosion product migration and deposition source term distribution is obtained based on the three-dimensional CFD flow field, temperature field and pressure field coupling, and the obtained dose rate model has more accurate calculation and analysis results, and can meet the safe and economic operation requirements of the unit operation and overhaul.

[0076] It can be understood that the above embodiments only express the preferred embodiments of the present application, the description is more specific and detailed, but it cannot be understood as the limitation of the patent scope of the present application; it should be pointed out that for ordinary skilled in the art, the above technical features can be freely combined without departing from the concept of the present application, and several modifications and improvements can be made, which belong to the protection scope of the present application; therefore, all equivalent transformations and modifications made with the claims of the present application shall belong to the scope of the claims of the present application.

Claims

1. A method for analyzing a dose rate applied to a regenerative heat exchanger of a containment system in a pressurized water reactor unit, characterized by, The method comprises the following steps: S1, generating a three-dimensional geometric model corresponding to the heat exchanger based on a CFD platform; S2, obtaining source item nuclides corresponding to the pressurized water reactor unit, and establishing a morphological conversion mechanism model corresponding to the source item nuclides; S3, obtaining a target working condition corresponding to the pressurized water reactor unit, and setting boundary conditions and initial conditions of the three-dimensional geometric model; S4, performing grid division on the three-dimensional geometric model to obtain a nuclide deposition rate selection target grid according to the obtained grid of the morphological conversion mechanism model; S5, establishing an MCNP model corresponding to the three-dimensional geometric model to obtain a dose rate of a predetermined part of the heat exchanger according to the MCNP model, the target grid and the morphological conversion mechanism model.

2. The dose rate analysis method according to claim 1, characterized by, In the step S1, the three-dimensional geometric model corresponding to the heat exchanger is generated based on the CFD platform; comprising: According to the length of the pipe section, the pipe diameter, the number of tubes, the bend curvature radius and the baffle arrangement of the heat exchanger, the three-dimensional geometric model is established.

3. The dose rate analysis method according to claim 1, characterized by, The morphological conversion mechanism model corresponding to the source item nuclides comprises: a deposition rate of dissolved corrosion products into particulate matter, a deposition rate of particulate corrosion products and an erosion rate corresponding to the source item nuclides; in the step S2, the morphological conversion mechanism model corresponding to the source item nuclides is established; comprising: The deposition rate of dissolved corrosion products into particulate matter, the deposition rate of particulate corrosion products and the erosion rate corresponding to the source item nuclides are obtained.

4. The dose rate analysis method according to claim 3, characterized by, The method further comprises: The deposition rate of dissolved corrosion products into particulate matter corresponding to the source item nuclides is obtained according to the following formula, where P w is the wet perimeter, C bulk (T) is the dissolved corrosion product concentration at the bulk coolant temperature T, C sat (T) is the dissolved corrosion product saturation concentration at the near-wall coolant temperature T, and K SD is the mass transfer coefficient.

5. The dose rate analysis method according to claim 3, characterized by, The method further comprises: The deposition rate of particulate corrosion products corresponding to the source item nuclides is obtained according to the following formula, where K PD is the mass transfer coefficient for particle corrosion products, C p,bulk (T) is the concentration of particulate matter at the primary coolant temperature T, C p,wall (T) is the concentration of particulate matter at the near-wall coolant temperature T.

6. The dose rate analysis method according to claim 3, characterized by, The method further comprises: the erosion rate corresponding to the source item nuclides is obtained according to the following formula, where ε is the erosion constant, τ is the shear stress, W a is the work deposited to the surface layer, E tot is the total adhesion energy, d is the deposit thickness.

7. The dose rate analysis method according to claim 1, characterized by, In the step S5, the MCNP model corresponding to the three-dimensional geometric model is established, comprising: A cell model of the MCNP model is generated based on materials, densities and geometric ranges corresponding to different regions in the heat exchanger; A surface card model of the MCNP model is generated based on surface morphologies in the structure of the heat exchanger; A data card model of the MCNP model is generated based on working parameters in the heat exchanger.

8. The dose rate analysis method according to claim 7, characterized in that, The data card model of the MCNP model comprises: A mode card for specifying the type of simulated particles; A material card for defining the source item nuclides; A source definition card for defining the characteristics of a particle source corresponding to the source item nuclides; An energy and conversion factor card for defining energy groups and corresponding physical quantity conversion factors; A detector card for defining physical quantities to be calculated and detection positions.

9. The method of dose rate analysis according to claim 1, wherein, In the step S2, The target working condition corresponding to the pressurized water reactor unit comprises: a power operation working condition of the pressurized water reactor unit, and / or a transient working condition of the pressurized water reactor unit at different pressure / temperature platforms in a major repair stage; and / or The setting of the boundary conditions and the initial conditions of the three-dimensional geometric model comprises setting the boundary conditions and the initial conditions of the inlets and outlets of the downflow and the upflow.

10. The dose rate analysis method of claim 1, wherein, In the step S4, the three-dimensional geometric model is meshed to obtain a target mesh for selecting a nuclide deposition rate of the morphological conversion mechanism model according to the obtained mesh; the step S4 comprises: Based on the structured mesh, the morphological conversion mechanism model corresponding to the source term nuclide is calculated by local adjustment of the structured mesh to obtain a steady state, and the target mesh is determined based on the steady state calculation result.

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