CN112989651A - Multi-physical field coupling method for reactor core - Google Patents

Multi-physical field coupling method for reactor core Download PDF

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CN112989651A
CN112989651A CN202110173575.3A CN202110173575A CN112989651A CN 112989651 A CN112989651 A CN 112989651A CN 202110173575 A CN202110173575 A CN 202110173575A CN 112989651 A CN112989651 A CN 112989651A
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王明军
张吉
田文喜
秋穗正
苏光辉
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Abstract

The invention discloses a reactor core multi-physical field coupling method, which comprises the following steps: 1. establishing a reactor physical calculation module; 2. establishing a reactor thermal analysis and calculation module; 3. establishing a corrosion product deposition calculation module; 4. establishing a reactor physical-thermal analysis-corrosion product deposition coupling calculation model; 5. performing reactor physical-thermal analysis-corrosion product deposition coupling calculation and solving; the method realizes reactor physical-thermal analysis-corrosion product deposition coupling calculation in the presence of the deposit on the surface of the fuel cladding, and the calculation result can provide theoretical basis for the long-term safe operation of the reactor and the power control of the reactor core.

Description

Multi-physical field coupling method for reactor core
Technical Field
The invention belongs to the technical field of method invention, and particularly relates to a method for physical-thermal analysis of a reactor of a nuclear reactor assembly and deposition coupling of corrosion products.
Background
The reactor core fuel elements form scale and deposits on the cladding surfaces during long-term operation in high temperature, high pressure and high radiation environments. The existence of the sediments can seriously affect the reactor core neutron physics and the heat transfer characteristics of fuel elements and a coolant, cause the hazards of reactor core power deviation, local heat transfer deterioration, local corrosion aggravation damage and the like, and bring great potential safety hazards to the safe operation of the nuclear reactor. In order to reduce the influence and harm of the corrosion of the reactor core fuel element cladding, the surface impurity migration and the deposition on the safe operation of the reactor as much as possible, accurately master the reactor core power distribution in the operation of the reactor and optimize a reactor power control system, the corrosion characteristics of the fuel element cladding, the evolution process of the deposits and the reactor core multi-physics field coupling technology need to be deeply researched.
At present, researches on corrosion characteristics of cladding materials of fuel elements of a reactor core and a sediment migration and deposition process are mostly based on a single-factor analysis method, and changes of actual operating states of the reactor core, particularly power spatial distribution, coolant flow and heat transfer characteristics and the like under long-term operating conditions are not considered. The phenomena of corrosion and surface impurity migration and deposition of the reactor fuel element cladding in the long-term operation process are extremely complex, the influence factors are many, the time span is large, and the current research is still in the starting stage. In the aspect of core multi-physics field fine simulation, most of researches are limited to the coupling between reactor physics and a system-level thermal hydraulic program at present, and the full three-dimensional high-fidelity nuclear thermal coupling research also faces huge technical challenges, and particularly has technical barriers in the fields of space grid mapping, efficient data transfer between physical fields, parallel computing efficiency and the like. The complex chemical reaction and corrosion product deposition process of the fuel element cladding surface in the harsh environments of high temperature, high pressure, strong radiation and the like are used as important factors influencing the reactor power distribution and power control system, and the reactor core fuel element cladding material corrosion-impurity deposition-neutron physics-thermal hydraulic power multi-physics coupling mechanism in the long-term operation process is yet to be further researched.
In view of the above problems, the present invention provides a method for calculating reactor physical-thermal analysis-corrosion product deposition coupling for nuclear reactor components.
Disclosure of Invention
In order to realize the calculation of the reactor physical-thermal-corrosion product deposition coupling of the nuclear reactor assembly under the condition of considering the existence of the corrosion product on the surface of the fuel rod, the invention establishes a deposition calculation module of the corrosion product on the surface of the fuel rod on the basis of the conventional reactor physical-thermal coupling calculation, considers the coupling mechanism of the deposit, the reactor physical and thermal and realizes the calculation of the reactor physical-thermal-corrosion product deposition coupling of the nuclear reactor assembly under the condition of considering the existence of the corrosion product on the surface of the fuel rod.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a reactor core multi-physical field coupling method comprises the following steps:
step 1: establishing a reactor physics calculation module
(1) Modeling a reactor assembly in reactor physical calculation software, wherein the model comprises fuel rods, a grid and a stirring wing, and dividing the model into grids for reactor physical calculation;
(2) establishing a reactor physical computation model
The reactor physical calculation model consists of a steady-state three-dimensional neutron transport equation and a burnup equation, wherein the steady-state three-dimensional neutron transport equation gives neutron flux distribution, and the burnup equation calculates the burnup of nuclides; the steady state three dimensional neutron transport equation is expressed as:
Figure BDA0002939614850000031
in the formula:
Figure BDA0002939614850000032
indicating a location
Figure BDA0002939614850000033
Where the energy is E and the direction of motion is
Figure BDA0002939614850000034
The neutron angle fluence rate of (a) is,
Figure BDA0002939614850000035
indicating a location
Figure BDA0002939614850000036
A macroscopic total cross section of neutrons with energy E,
Figure BDA0002939614850000037
indicating a location
Figure BDA0002939614850000038
Where the energy is E and the direction of motion is
Figure BDA0002939614850000039
The source of scattered neutrons of (a),
Figure BDA00029396148500000310
indicating a location
Figure BDA00029396148500000311
Where the energy is E and the direction of motion is
Figure BDA00029396148500000312
An assumed isotropic fission neutron source of (a);
the expression of the burnup equation is as follows:
Figure BDA00029396148500000313
in the formula: n is a radical ofi(t) represents the concentration of the nuclide i at time t,/ijTo representRatio of nucleation elements i in nuclide j due to radioactive decay, λjRepresenting the decay constant, N, of a nuclide jjDenotes the concentration of a nuclide j, fikIs the proportion of the species k that forms the species i due to neutron reaction,
Figure BDA00029396148500000314
denotes the mean neutron fluence rate, σkShowing the microscopic cross-section of the nuclide k, NkDenotes the concentration of the nuclide k, λiRepresenting the decay constant, σ, of the nuclide iiShowing the microscopic section of the nuclide i, NiRepresents the concentration of the nuclide i;
step 2: establishing reactor thermal analysis and calculation module
Establishing a thermal analysis calculation module in computational fluid dynamics software, considering the flow condition of the coolant and the conjugate heat transfer between the coolant and the fuel rod, wherein the established thermal analysis calculation module comprises a flow model, a turbulence model and a conjugate heat transfer model of the coolant, and the steps are as follows:
(1) guiding the geometric model of the reactor assembly into grid generation software to divide a control body to form a grid model of the reactor assembly suitable for thermal analysis and calculation, and guiding the grid model of the reactor assembly into computational fluid dynamics software to form a calculation model of the reactor assembly;
(2) modeling coolant flow
The flow condition of the coolant is set to a single-phase turbulent flow, and the continuity equation of the flow is as follows:
Figure BDA0002939614850000041
in the formula: cool denotes the coolant, pcoolAs the density of the coolant is to be,
Figure BDA0002939614850000042
is a coolant velocity field;
the momentum equation for coolant flow is described using the incompressible Navier-Stokes equation:
Figure BDA0002939614850000043
in the formula: p represents pressure, μ represents kinematic viscosity;
(3) establishing turbulence model
Solving the simulation of the turbulence by adopting a Reynolds time-average stress method and based on a k-epsilon model;
the method decomposes the instantaneous velocity field into time-average quantity by Reynolds time-average stress method
Figure BDA0002939614850000044
And amount of pulsation
Figure BDA0002939614850000045
Figure BDA0002939614850000046
The decomposed instantaneous velocity field is brought into a momentum equation to obtain a time-averaged Navier-Stokes equation, and a new unknown quantity, namely a Reynolds stress term, is introduced at the same time
Figure BDA0002939614850000047
The form is as follows:
Figure BDA0002939614850000048
wherein u ', v ' and w ' respectively represent
Figure BDA0002939614850000049
The reynolds stress term is calculated using a vortex-viscous model based on the bucinnek approximation for the velocity components in the x, y and z directions as:
Figure BDA0002939614850000051
wherein
Figure BDA0002939614850000052
In the case of the kronecker symbol,
Figure BDA0002939614850000053
is the strain tensor, μtRepresenting the turbulent viscosity, k being the turbulent kinetic energy;
Figure BDA0002939614850000054
building a turbulence model based on a standard k-epsilon model to seal the flow equation, turbulence viscosity, mutIt is calculated that,
Figure BDA0002939614850000055
ε is the turbulent dissipation ratio, CμFor the empirical coefficient of turbulence, C for the standard k-epsilon modelμK is the turbulent kinetic energy, 0.09, which has a value of half the reynolds stress tensor,
Figure BDA0002939614850000056
(4) establishing a conjugate heat transfer model
Besides solving the flow equation, the computational fluid dynamics software also needs to solve the problems of convective heat transfer and heat conduction, namely solving the heat transfer problem in the solid and the coolant fluid at the same time, and the coupled heat transfer process is called conjugate heat transfer;
the established conjugate heat transfer model comprises a temperature control equation of the coolant and a temperature control equation in the solid domain; the temperature control equation of the coolant is as follows:
Figure BDA0002939614850000057
in the formula: t iscoolIs the temperature of the coolant, cpIs the specific heat capacity at constant pressure at the pressure p,
Figure BDA0002939614850000058
density of heat flow, q ″, transferred from the fuel rod cladding to the coolant'coolFor the volumetric heat release rate of the coolant, β is the volumetric thermal expansion coefficient, and Φ is the dissipation function:
Figure BDA0002939614850000061
in the formula:
Figure BDA0002939614850000062
is the tensor of friction;
sol denotes the solid domain, including fuel pellets and cladding, and the temperature control equation in the solid domain is:
Figure BDA0002939614850000063
in the formula: t issolIs the temperature of the solid domain, psolIs the density of the solid domain, and,
Figure BDA0002939614850000064
is the thermal conductivity in the solid domain, q'solIs the volumetric heat release rate of the solid domain;
the heat transfer equations of the fluid and the solid are solved by coupling the temperature and heat flux variables at the solid/fluid interface;
and step 3: establishing a corrosion product deposition calculation module
In calculating the deposition of corrosion products, the particles in the coolant considered include: boron, lithium, hydrogen, soluble nickel, soluble iron and particulate nickel ferrite; establishing a heat transfer model, a deposition kinetic model and a material transport model in corrosion deposition products, and comprising the following steps of:
(1) establishing a geometric model of the fuel rod according to physical characteristics of corrosion product deposition, and dividing a radial control body on the surface of the fuel rod in a corrosion product deposition calculation module for calculation of the corrosion product deposition;
(2) modeling heat transfer
The heat transfer model comprises a heat conduction equation in corrosion products and calculation of thermal diffusivity, density and effective specific heat capacity; the equation for thermal conductivity in corrosion deposition products is:
Figure BDA0002939614850000065
in the formula:
Figure BDA0002939614850000071
in the representation of corrosion products
Figure BDA0002939614850000072
The temperature at the time t at the location,
Figure BDA0002939614850000073
to represent
Figure BDA0002939614850000074
The thermal diffusivity at the time t at a location,
Figure BDA0002939614850000075
denotes a porosity of
Figure BDA0002939614850000076
Saturation temperature of coolant is TsatAt a temperature of TCRUDThe local thermal trap of (1);
thermal diffusivity of corrosion deposition products DtCalculated from the following formula:
Figure BDA0002939614850000077
wherein
Figure BDA0002939614850000078
Indicating corrosionIn the product
Figure BDA0002939614850000079
Temperature at position TCRUDThe coefficient of thermal diffusion at the time of use,
Figure BDA00029396148500000710
in the representation of corrosion products
Figure BDA00029396148500000711
Temperature at position TCRUDThe effective thermal conductivity at the time of the thermal treatment,
Figure BDA00029396148500000712
in the representation of corrosion products
Figure BDA00029396148500000713
Temperature at position TCRUDEffective specific heat capacity; effective coefficient of thermal conductivity
Figure BDA00029396148500000726
Coefficient of thermal conductivity of coolant
Figure BDA00029396148500000714
And thermal conductivity of corrosion deposition products
Figure BDA00029396148500000715
Porosity is carried out
Figure BDA00029396148500000716
The weight of the (c) is calculated,
Figure BDA00029396148500000717
Figure BDA00029396148500000718
in the products of corrosion deposition
Figure BDA00029396148500000719
The porosity of (d);
density of solid parts in corrosion products pcExpressing density ρ of corrosion deposition products per volume by porosity weightingbulk，
Figure BDA00029396148500000720
Similarly, corrosion deposition products are in place
Figure BDA00029396148500000721
At a temperature of TCRUDEffective specific heat capacity of
Figure BDA00029396148500000722
Is determined by the density ρ of the coolantcoolAnd density of solid portion of corrosion deposition product ρcTo weight-compute:
Figure BDA00029396148500000723
wherein
Figure BDA00029396148500000724
Denotes the coolant temperature TcoolThe specific heat capacity of (a) is,
Figure BDA00029396148500000725
the solid fraction temperature of corrosion products is TCRUDSpecific heat capacity of
(3) Establishing a deposition dynamics model
The deposition on the surface of the deposited layer of the corrosion product and the deposition at the internal pores are simultaneously considered in the surface deposition kinetic part; particles considered to be deposited on the surface of corrosion deposition products include nickel ferrite, nickel oxide and ferroferric oxide; the established deposition kinetic model comprises a deposition kinetic rate equation of each substance deposited on the surface and an equation for controlling the sedimentation of particles in pores;
the established deposition kinetic rate equation of each substance deposited on the surface is as follows:
Figure BDA0002939614850000081
wherein
Figure BDA0002939614850000082
Representing the concentration of particles in the solid region in the corrosion deposition product,
Figure BDA0002939614850000083
indicating the concentration of particles in the pore region of the corrosion deposition product,
Figure BDA0002939614850000084
representing the arrhenius rate coefficient of the particles in the pore region where the coolant is in an unsaporized state,
Figure BDA0002939614850000085
representing the Arrhenius rate coefficient, q ″, of particles in the pore region where the coolant is in the boiling stateCRUDIndicating boiling heat flux density in the corrosion deposition products,
Figure BDA0002939614850000086
for deposition losses due to turbulence, the values are the kinetic energy k of the turbulence and the tunable constant xeThe product of (a) and (b),
Figure BDA0002939614850000087
the particles deposited in the pores inside the corrosion deposition product include nickel ferrite, nickel oxide, ferroferric oxide, lithium tetraborate, lithium metaborate, boromagnesite and metaborate, and the equation governing the sedimentation of these particles in the pores is:
Figure BDA0002939614850000088
wherein A (eta) is putridThe porosity in the etched deposit product is the surface area of the pores at η,
Figure BDA0002939614850000089
is the concentration of particles dissolved in the coolant,
Figure BDA00029396148500000810
is the solubility of the particles, calculated by models of thermodynamics and solubility;
Figure BDA00029396148500000811
the arrhenius rate coefficient of the dissolved particles,
(4) establishing a material transport model
Establishing a material transport model comprising a soluble transport equation of particles:
Figure BDA0002939614850000091
in the formula
Figure BDA0002939614850000092
And
Figure BDA0002939614850000093
are defined as being, respectively, a,
Figure BDA0002939614850000094
Figure BDA0002939614850000095
Figure BDA0002939614850000096
where Δ L is the calculated radial length, Δ r is the radial thickness of the computational mesh, Dpart(TCRUD) The particles are at a temperature TCRUDThe coefficient of thermal diffusion at the time of use,
Figure BDA0002939614850000097
is the concentration of particles in the vapor generated by local boiling in the products of corrosion deposition, vvaporIs the steam flow velocity, vbIs the boiling velocity, the steam flow velocity and the boiling velocity being linked by conservation of mass, i.e.
ρvaporvvapor＝ρcoolvb
ρvaporIs the density of the steam;
and 4, step 4: establishing a reactor physical-thermal analysis-corrosion product deposition coupling calculation model
A simplified form of the coupling equation is given to account for each computation block input and output and the coupling variables between them;
nuclide concentration NjThe physical quantity comprises all related nuclides j, the composition and boron concentration of corrosion deposition products are provided by a corrosion deposition product calculation module, and the nuclide concentration N is input into a reactor physical calculation modulejNuclide microscopic cross section sigma, nuclide temperature T and coolant density rhocoolComposition is carried out; the operator N expresses the neutron transport equation to be solved, and the local neutron fluence rate phi and the critical coolant boron concentration are obtained
Figure BDA0002939614850000098
As shown in the following formula:
Figure BDA0002939614850000099
the power density operator P represents the distribution of the power density calculated by the neutron fluence rate,
q″′＝P(φ)
the thermodynamic hydraulic analysis model established in computational fluid dynamics software mainly comprises a Navier-Stokes equation and a temperature equation for solving the conjugate heat transfer, wherein an operator F represents the Navier-Stokes equation, an operator H represents the temperature equation, and the two parts jointly solve the flow and heat transfer characteristics in the assembly;
by the distribution q' ″ of the input power density, the coolant temperature TcoolAnd the thermal resistance gamma of corrosion deposition products, and calculating the heat flow density q' and the temperature T of the surface of the hullsolid，
(Tsolid,q″)＝H(q″′,Tcool,Γ)
After the heat current density q' on the surface of the cladding is input, the temperature T of the coolant is obtained by solving the Navier-Stokes equationcoolAnd density ρcoolAnd turbulent kinetic energy k near the surface of the cladding;
(Tcool,ρcool,k)＝F(q″)
the reactor physics calculating module and the thermal hydraulic analysis calculating module pass through q', Tsolid、TcoolAnd ρcoolAre coupled together;
in the corrosion deposition product calculation module, the input comprises the cladding heat flow density q', and the coolant temperature T of the contact section of the corrosion deposition product and the coolantcoolTurbulent kinetic energy k, concentration of boron in coolant
Figure BDA0002939614850000101
And rate of neutron-boron reaction RBThe output includes the thermal resistance gamma of corrosion deposition product and the concentration of nuclide in the composition
Figure BDA0002939614850000102
The calculation is shown as follows, and operator C represents the solution process of the corrosion product deposition module:
Figure BDA0002939614850000103
the corrosion deposition product calculation module and the thermal hydraulic analysis calculation module calculate the temperature T of the contact section of the corrosion deposition product and the coolant through the cladding heat flow density q ″coolThe turbulent kinetic energy k and the corrosion deposition product thermal resistance gamma are coupled together; corrosion sinkThe product calculation module and the reactor physical calculation module pass the concentration of boron in the coolant
Figure BDA0002939614850000111
Reaction rate of neutrons with boron RBAnd nuclide concentration in corrosion deposition product composition
Figure BDA0002939614850000112
Are coupled together;
and 5: the steps of solving the coupling solution by carrying out reactor physical-thermal analysis-corrosion product deposition coupling calculation are as follows:
(1) setting an initial calculation working condition for a reactor physical calculation module, and calculating to obtain the initial power density distribution of a reactor assembly according to the set condition; based on a grid mapping technology, firstly carrying out interpolation processing on discrete physical quantities of each node obtained by calculation of an original grid to obtain spatial continuous distribution of the physical quantities, then obtaining corresponding physical quantity values according to spatial coordinates of each node of a target grid based on the distribution, realizing grid mapping of calculation results, thereby completing data exchange between modules, developing a coupling interface module for different modules, transmitting power distribution obtained by reactor physical calculation to a thermal analysis calculation module through the coupling interface module, setting distribution of an initial coolant flow field and a temperature field obtained by the thermal analysis calculation, carrying out calculation, and obtaining fuel surface heat flow density, cladding surface temperature, coolant temperature and density, fuel temperature and turbulent kinetic energy through calculation;
(2) transmitting the calculated boron concentration, neutron flux, heat flux density, cladding surface temperature, coolant temperature and turbulent kinetic energy to a corrosion product deposition calculation model by a coupling interface module, updating the setting, and calculating to obtain the component composition of the corrosion deposition product and the thermal resistance of the deposit;
(3) transferring the coolant temperature, density and fuel temperature calculated by the thermal analysis and calculation module to a reactor physical calculation module through a coupling interface module, transferring the component ingredients calculated by the corrosion product deposition calculation module to the reactor physical calculation module through the coupling interface module, and obtaining the component power density, boron concentration and neutron flux through the reactor physical calculation module;
(4) the calculated power density distribution and sediment thermal resistance of the assembly are transmitted to a thermal analysis and calculation module through a coupling interface module, and a flow field and a temperature field of the updated assembly are calculated;
(5) and (4) judging whether residual errors of the coolant flow rate, the coolant temperature and the fuel rod internal temperature meet a convergence criterion, namely are smaller than a preset residual error value, and if not, repeating the steps from (2) to (4) until convergence.
The invention has the following advantages and beneficial effects:
1. the component components and the thermal resistance of the corrosion products on the surfaces of the components can be calculated by coupling calculation of the established fuel rod surface corrosion product deposition module and reactor physical and thermal programs, and the calculation is used for the safe operation analysis of the reactor.
2. The method comprises the steps of considering a corrosion product deposition, neutron physics and thermal hydraulic force mutual feedback mechanism in the presence of the fuel rod surface deposits, performing reactor physics-thermal analysis-corrosion product deposition coupling calculation, obtaining a power distribution rule, reactor core flow heat transfer characteristics and a key safety parameter range under the long-term operation working condition of the reactor, providing a theoretical basis for the long-term safe operation of the reactor and the reactor core power control, and providing technical support for the technical development of the numerical reactor.
3. The coupling method belongs to an explicit coupling method, data are transmitted through a coupling interface module after program calculation is completed, the realization is simple, a calculation model and initial conditions can be adjusted by setting a relevant input card, and calculation results under different working conditions are obtained.
4. The scheme of reactor physical-thermal analysis-corrosion product deposition coupling calculation provided by the invention is suitable for most of computational fluid dynamics software and thermal hydraulic analysis software at present, such as FLUENT, RELAP5, COBRA and the like.
Drawings
FIG. 1 is a schematic view of a reactor core fuel rod and fuel assembly.
FIG. 2 is a schematic view of a corrosion product deposition structure.
FIG. 3 is a flow chart of the method calculation of the present invention.
Fig. 4 is a schematic diagram of a physical field coupling mechanism.
Detailed Description
The invention is described in further detail below with reference to the following figures and detailed description:
as shown in fig. 3, the present invention relates to a reactor core multi-physics coupling method, which comprises the following steps:
step 1: establishing a reactor physics calculation module
(1) Modeling a reactor assembly in reactor physical computing software, wherein the built model comprises fuel rods, a grid and a stirring wing, as shown in figure 1, and dividing the built model into grids for reactor physical computing;
(2) establishing a reactor physical computation model
The reactor physical calculation model consists of a steady-state three-dimensional neutron transport equation and a burnup equation, wherein the steady-state three-dimensional neutron transport equation gives neutron flux distribution, and the burnup equation calculates the burnup of nuclides; the steady state three dimensional neutron transport equation is expressed as:
Figure BDA0002939614850000131
in the formula:
Figure BDA0002939614850000132
indicating a location
Figure BDA0002939614850000133
Where the energy is E and the direction of motion is
Figure BDA0002939614850000134
The neutron angle fluence rate of (a) is,
Figure BDA0002939614850000135
indicating a location
Figure BDA0002939614850000136
A macroscopic total cross section of neutrons with energy E,
Figure BDA0002939614850000137
indicating a location
Figure BDA0002939614850000141
Where the energy is E and the direction of motion is
Figure BDA0002939614850000142
The source of scattered neutrons of (a),
Figure BDA0002939614850000143
indicating a location
Figure BDA0002939614850000144
Where the energy is E and the direction of motion is
Figure BDA0002939614850000145
An assumed isotropic fission neutron source of (a);
the expression of the burnup equation is as follows:
Figure BDA0002939614850000146
in the formula: n is a radical ofi(t) represents the concentration of the nuclide i at time t,/ijDenotes the ratio of the nucleation element i in the nuclide j due to radioactive decay, lambdajRepresenting the decay constant, N, of a nuclide jjDenotes the concentration of a nuclide j, fikIs the proportion of the species k that forms the species i due to neutron reaction,
Figure BDA0002939614850000147
denotes the mean neutron fluence rate, σkShowing the microscopic cross-section of the nuclide k, NkDenotes the concentration of the nuclide k, λiRepresenting the decay constant, σ, of the nuclide iiShowing the microscopic section of the nuclide i, NiRepresents the concentration of the nuclide i;
step 2: establishing reactor thermal analysis and calculation module
Establishing a thermal analysis calculation module in computational fluid dynamics software, considering the flow condition of the coolant and the conjugate heat transfer between the coolant and the fuel rod, wherein the established thermal analysis calculation module comprises a flow model, a turbulence model and a conjugate heat transfer model of the coolant, and the steps are as follows:
(1) guiding the geometric model of the reactor assembly into grid generation software to divide a control body to form a grid model of the reactor assembly suitable for thermal analysis and calculation, and guiding the grid model of the reactor assembly into computational fluid dynamics software to form a calculation model of the reactor assembly;
(2) modeling coolant flow
The flow condition of the coolant is set to a single-phase turbulent flow, and the continuity equation of the flow is as follows:
Figure BDA0002939614850000148
in the formula: cool denotes the coolant, pcoolAs the density of the coolant is to be,
Figure BDA0002939614850000149
is a coolant velocity field;
the momentum equation for coolant flow is described using the incompressible Navier-Stokes equation:
Figure BDA0002939614850000151
in the formula: p represents pressure, μ represents kinematic viscosity;
(3) establishing turbulence model
Solving the simulation of the turbulence by adopting a Reynolds time-average stress method and based on a k-epsilon model;
the method decomposes the instantaneous velocity field into time-average quantity by Reynolds time-average stress method
Figure BDA0002939614850000152
And amount of pulsation
Figure BDA0002939614850000153
Figure BDA0002939614850000154
The decomposed instantaneous velocity field is brought into a momentum equation to obtain a time-averaged Navier-Stokes equation, and a new unknown quantity, namely a Reynolds stress term, is introduced at the same time
Figure BDA0002939614850000155
The form is as follows:
Figure BDA0002939614850000156
wherein u ', v ' and w ' respectively represent
Figure BDA0002939614850000157
The reynolds stress term is calculated using a vortex-viscous model based on the bucinnek approximation for the velocity components in the x, y and z directions as:
Figure BDA0002939614850000158
wherein
Figure BDA0002939614850000159
In the case of the kronecker symbol,
Figure BDA00029396148500001510
is the strain tensor, μtRepresenting the turbulent viscosity, k being the turbulent kinetic energy;
Figure BDA00029396148500001511
building a turbulence model based on a standard k-epsilon model to seal a flowEquation of motion, turbulent viscosity μtIt is calculated that,
Figure BDA0002939614850000161
ε is the turbulent dissipation ratio, CμFor the empirical coefficient of turbulence, C for the standard k-epsilon modelμK is the turbulent kinetic energy, 0.09, which has a value of half the reynolds stress tensor,
Figure BDA0002939614850000162
(4) establishing a conjugate heat transfer model
Besides solving the flow equation, the computational fluid dynamics software also needs to solve the problems of convective heat transfer and heat conduction, namely solving the heat transfer problem in the solid and the coolant fluid at the same time, and the coupled heat transfer process is called conjugate heat transfer;
the established conjugate heat transfer model comprises a temperature control equation of the coolant and a temperature control equation in the solid domain; the temperature control equation of the coolant is as follows:
Figure BDA0002939614850000163
in the formula: t iscoolIs the temperature of the coolant, cpIs the specific heat capacity at constant pressure at the pressure p,
Figure BDA0002939614850000164
density of heat flow, q ″, transferred from the fuel rod cladding to the coolant'coolFor the volumetric heat release rate of the coolant, β is the volumetric thermal expansion coefficient, and Φ is the dissipation function:
Figure BDA0002939614850000165
in the formula:
Figure BDA0002939614850000166
is the tensor of friction;
sol denotes the solid domain, including fuel pellets and cladding, and the temperature control equation in the solid domain is:
Figure BDA0002939614850000171
in the formula: t issolIs the temperature of the solid domain, psolIs the density of the solid domain, and,
Figure BDA0002939614850000172
is the thermal conductivity in the solid domain, q'solIs the volumetric heat release rate of the solid domain;
the heat transfer equations of the fluid and the solid are solved by coupling the temperature and heat flux variables at the solid/fluid interface;
and step 3: establishing a corrosion product deposition calculation module
In calculating the deposition of corrosion products, the particles in the coolant considered include: boron, lithium, hydrogen, soluble nickel, soluble iron and particulate nickel ferrite; establishing a heat transfer model, a deposition kinetic model and a material transport model in corrosion deposition products, and comprising the following steps of:
(1) according to the physical characteristics of corrosion product deposition, as shown in fig. 2, a geometric model of the fuel rod is established, and a control body in the radial direction of the surface of the fuel rod is divided in a corrosion product deposition calculation module and is used for calculating the corrosion product deposition;
(2) modeling heat transfer
The heat transfer model comprises a heat conduction equation in corrosion products and calculation of thermal diffusivity, density and effective specific heat capacity; the equation for thermal conductivity in corrosion deposition products is:
Figure BDA0002939614850000173
in the formula:
Figure BDA0002939614850000174
in the representation of corrosion products
Figure BDA0002939614850000175
The temperature at the time t at the location,
Figure BDA0002939614850000176
to represent
Figure BDA0002939614850000177
The thermal diffusivity at the time t at a location,
Figure BDA0002939614850000178
denotes a porosity of
Figure BDA0002939614850000179
Saturation temperature of coolant is TsatAt a temperature of TCRUDThe local thermal trap of (1);
thermal diffusivity of corrosion deposition products DtCalculated from the following formula:
Figure BDA00029396148500001710
wherein
Figure BDA0002939614850000181
In the representation of corrosion products
Figure BDA0002939614850000182
Temperature at position TCRUDThe coefficient of thermal diffusion at the time of use,
Figure BDA0002939614850000183
in the representation of corrosion products
Figure BDA0002939614850000184
Temperature at position TCRUDThe effective thermal conductivity at the time of the thermal treatment,
Figure BDA0002939614850000185
in the representation of corrosion products
Figure BDA0002939614850000186
Temperature at position TCRUDEffective specific heat capacity; effective coefficient of thermal conductivity
Figure BDA0002939614850000187
Coefficient of thermal conductivity of coolant
Figure BDA0002939614850000188
And thermal conductivity of corrosion deposition products
Figure BDA0002939614850000189
Porosity is carried out
Figure BDA00029396148500001810
The weight of the (c) is calculated,
Figure BDA00029396148500001811
Figure BDA00029396148500001812
in the products of corrosion deposition
Figure BDA00029396148500001813
The porosity of (d);
density of solid parts in corrosion products pcExpressing density ρ of corrosion deposition products per volume by porosity weightingbulk，
Figure BDA00029396148500001814
Similarly, corrosion deposition products are in place
Figure BDA00029396148500001815
At a temperature of TCRUDEffective specific heat capacity of
Figure BDA00029396148500001816
Is determined by the density ρ of the coolantcoolAnd density of solid portion of corrosion deposition product ρcTo weight-compute:
Figure BDA00029396148500001817
wherein
Figure BDA00029396148500001818
Denotes the coolant temperature TcoolThe specific heat capacity of (a) is,
Figure BDA00029396148500001819
the solid fraction temperature of corrosion products is TCRUDSpecific heat capacity of
(3) Establishing a deposition dynamics model
The deposition on the surface of the deposited layer of the corrosion product and the deposition at the internal pores are simultaneously considered in the surface deposition kinetic part; particles considered to be deposited on the surface of corrosion deposition products include nickel ferrite, nickel oxide and ferroferric oxide; the established deposition kinetic model comprises a deposition kinetic rate equation of each substance deposited on the surface and an equation for controlling the sedimentation of particles in pores;
the established deposition kinetic rate equation of each substance deposited on the surface is as follows:
Figure BDA0002939614850000191
wherein
Figure BDA0002939614850000192
Representing the concentration of particles in the solid region in the corrosion deposition product,
Figure BDA0002939614850000193
indicating the concentration of particles in the pore region of the corrosion deposition product,
Figure BDA0002939614850000194
representing the arrhenius rate coefficient of the particles in the pore region where the coolant is in an unsaporized state,
Figure BDA0002939614850000195
representing the Arrhenius rate coefficient, q ″, of particles in the pore region where the coolant is in the boiling stateCRUDIndicating boiling heat flux density in the corrosion deposition products,
Figure BDA0002939614850000196
for deposition losses due to turbulence, the values are the kinetic energy k of the turbulence and the tunable constant xeThe product of (a) and (b),
Figure BDA0002939614850000197
the particles deposited in the pores inside the corrosion deposition product include nickel ferrite, nickel oxide, ferroferric oxide, lithium tetraborate, lithium metaborate, boromagnesite and metaborate, and the equation governing the sedimentation of these particles in the pores is:
Figure BDA0002939614850000198
wherein A (η) is the surface area of the pores at which the porosity in the corrosion deposition product is η,
Figure BDA0002939614850000199
is the concentration of particles dissolved in the coolant,
Figure BDA00029396148500001910
is the solubility of the particles, calculated by models of thermodynamics and solubility;
Figure BDA00029396148500001911
the arrhenius rate coefficient of the dissolved particles,
(4) establishing a material transport model
Establishing a material transport model comprising a soluble transport equation of particles:
Figure BDA00029396148500001912
in the formula
Figure BDA00029396148500001913
And
Figure BDA00029396148500001914
are defined as being, respectively, a,
Figure BDA00029396148500001915
Figure BDA0002939614850000201
Figure BDA0002939614850000202
where Δ L is the calculated radial length, Δ r is the radial thickness of the computational mesh, Dpart(TCRUD) The particles are at a temperature TCRUDThe coefficient of thermal diffusion at the time of use,
Figure BDA0002939614850000203
is the concentration of particles in the vapor generated by local boiling in the products of corrosion deposition, vvaporIs the steam flow velocity, vbIs the boiling velocity, the steam flow velocity and the boiling velocity being linked by conservation of mass, i.e.
ρvaporvvapor＝ρcoolvb
ρvaporIs the density of the steam;
and 4, step 4: establishing a reactor physical-thermal analysis-corrosion product deposition coupling calculation model
A simplified form of the coupling equation is given to illustrate the input and output of each calculation module and the coupling variables between them, and the coupling between the various modules is shown in fig. 4;
nuclide concentration NjThe physical quantity comprises all related nuclides j, the composition and boron concentration of corrosion deposition products are provided by a corrosion deposition product calculation module, and the nuclide concentration N is input into a reactor physical calculation modulejNuclide microscopic cross section sigma, nuclide temperature T and coolant density rhocoolComposition is carried out; the operator N expresses the neutron transport equation to be solved, and the local neutron fluence rate phi and the critical coolant boron concentration are obtained
Figure BDA0002939614850000204
As shown in the following formula:
Figure BDA0002939614850000205
the power density operator P represents the distribution of the power density calculated by the neutron fluence rate,
q″′＝P(φ)
the thermodynamic hydraulic analysis model established in computational fluid dynamics software mainly comprises a Navier-Stokes equation and a temperature equation for solving the conjugate heat transfer, wherein an operator F represents the Navier-Stokes equation, an operator H represents the temperature equation, and the two parts jointly solve the flow and heat transfer characteristics in the assembly;
by the distribution q' ″ of the input power density, the coolant temperature TcoolAnd the thermal resistance gamma of corrosion deposition products, and calculating the heat flow density q' and the temperature T of the surface of the hullsolid，
(Tsolid,q″)＝H(q″′,Tcool,Γ)
After the heat current density q' on the surface of the cladding is input, the temperature T of the coolant is obtained by solving the Navier-Stokes equationcoolAnd density ρcoolAnd turbulent flow near the surface of the envelopeK is obtained;
(Tcool,ρcool,k)＝F(q″)
the reactor physics calculating module and the thermal hydraulic analysis calculating module pass through q', Tsolid、TcoolAnd ρcoolAre coupled together;
in the corrosion deposition product calculation module, the input comprises the cladding heat flow density q', and the coolant temperature T of the contact section of the corrosion deposition product and the coolantcoolTurbulent kinetic energy k, concentration of boron in coolant
Figure BDA0002939614850000211
And rate of neutron-boron reaction RBThe output includes the thermal resistance gamma of corrosion deposition product and the concentration of nuclide in the composition
Figure BDA0002939614850000212
The calculation is shown as follows, and operator C represents the solution process of the corrosion product deposition module:
Figure BDA0002939614850000213
the corrosion deposition product calculation module and the thermal hydraulic analysis calculation module calculate the temperature T of the contact section of the corrosion deposition product and the coolant through the cladding heat flow density q ″coolThe turbulent kinetic energy k and the corrosion deposition product thermal resistance gamma are coupled together; the corrosion deposition product calculation module and the reactor physical calculation module pass the concentration of boron in the coolant
Figure BDA0002939614850000214
Reaction rate of neutrons with boron RBAnd nuclide concentration in corrosion deposition product composition
Figure BDA0002939614850000215
Are coupled together;
and 5: the steps of solving the coupling solution by carrying out reactor physical-thermal analysis-corrosion product deposition coupling calculation are as follows:
(1) setting an initial calculation working condition for a reactor physical calculation module, and calculating to obtain the initial power density distribution of a reactor assembly according to the set condition; based on a grid mapping technology, firstly carrying out interpolation processing on discrete physical quantities of each node obtained by calculation of an original grid to obtain spatial continuous distribution of the physical quantities, then obtaining corresponding physical quantity values according to spatial coordinates of each node of a target grid based on the distribution, realizing grid mapping of calculation results, thereby completing data exchange between modules, developing a coupling interface module for different modules, transmitting power distribution obtained by reactor physical calculation to a thermal analysis calculation module through the coupling interface module, setting distribution of an initial coolant flow field and a temperature field obtained by the thermal analysis calculation, carrying out calculation, and obtaining fuel surface heat flow density, cladding surface temperature, coolant temperature and density, fuel temperature and turbulent kinetic energy through calculation;
(2) transmitting the calculated boron concentration, neutron flux, heat flux density, cladding surface temperature, coolant temperature and turbulent kinetic energy to a corrosion product deposition calculation model by a coupling interface module, updating the setting, and calculating to obtain the component composition of the corrosion deposition product and the thermal resistance of the deposit;
(3) transferring the coolant temperature, density and fuel temperature calculated by the thermal analysis and calculation module to a reactor physical calculation module through a coupling interface module, transferring the component ingredients calculated by the corrosion product deposition calculation module to the reactor physical calculation module through the coupling interface module, and obtaining the component power density, boron concentration and neutron flux through the reactor physical calculation module;
(4) the calculated power density distribution and sediment thermal resistance of the assembly are transmitted to a thermal analysis and calculation module through a coupling interface module, and a flow field and a temperature field of the updated assembly are calculated;
(5) and (4) judging whether residual errors of the coolant flow rate, the coolant temperature and the fuel rod internal temperature meet a convergence criterion, namely are smaller than a preset residual error value, and if not, repeating the steps from (2) to (4) until convergence.
While the invention has been described in further detail with reference to specific preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (1)

1. A reactor core multi-physical field coupling method is characterized in that: the method comprises the following steps:
step 1: establishing a reactor physics calculation module
(1) Modeling a reactor assembly in reactor physical calculation software, wherein the model comprises fuel rods, a grid and a stirring wing, and dividing the model into grids for reactor physical calculation;
(2) establishing a reactor physical computation model
The reactor physical calculation model consists of a steady-state three-dimensional neutron transport equation and a burnup equation, wherein the steady-state three-dimensional neutron transport equation gives neutron flux distribution, and the burnup equation calculates the burnup of nuclides; the steady state three dimensional neutron transport equation is expressed as:
Figure FDA0002939614840000011
in the formula:
Figure FDA0002939614840000012
indicating a location
Figure FDA0002939614840000013
Where the energy is E and the direction of motion is
Figure FDA0002939614840000014
The neutron angle fluence rate of (a) is,
Figure FDA0002939614840000015
to representPosition of
Figure FDA0002939614840000016
A macroscopic total cross section of neutrons with energy E,
Figure FDA0002939614840000017
indicating a location
Figure FDA0002939614840000018
Where the energy is E and the direction of motion is
Figure FDA0002939614840000019
The source of scattered neutrons of (a),
Figure FDA00029396148400000110
indicating a location
Figure FDA00029396148400000111
Where the energy is E and the direction of motion is
Figure FDA00029396148400000112
An assumed isotropic fission neutron source of (a);
the expression of the burnup equation is as follows:
Figure FDA00029396148400000113
in the formula: n is a radical ofi(t) represents the concentration of the nuclide i at time t,/ijDenotes the ratio of the nucleation element i in the nuclide j due to radioactive decay, lambdajRepresenting the decay constant, N, of a nuclide jjDenotes the concentration of a nuclide j, fikIs the proportion of the species k that forms the species i due to neutron reaction,
Figure FDA00029396148400000114
denotes the mean neutron fluence rate, σkShowing the microscopic cross-section of the nuclide k, NkDenotes the concentration of the nuclide k, λiRepresenting the decay constant, σ, of the nuclide iiShowing the microscopic section of the nuclide i, NiRepresents the concentration of the nuclide i;
step 2: establishing reactor thermal analysis and calculation module
Establishing a thermal analysis calculation module in computational fluid dynamics software, considering the flow condition of the coolant and the conjugate heat transfer between the coolant and the fuel rod, wherein the established thermal analysis calculation module comprises a flow model, a turbulence model and a conjugate heat transfer model of the coolant, and the steps are as follows:
(1) guiding the geometric model of the reactor assembly into grid generation software to divide a control body to form a grid model of the reactor assembly suitable for thermal analysis and calculation, and guiding the grid model of the reactor assembly into computational fluid dynamics software to form a calculation model of the reactor assembly;
(2) modeling coolant flow
The flow condition of the coolant is set to a single-phase turbulent flow, and the continuity equation of the flow is as follows:
Figure FDA0002939614840000021
in the formula: cool denotes the coolant, pcoolAs the density of the coolant is to be,
Figure FDA0002939614840000022
is a coolant velocity field;
the momentum equation for coolant flow is described using the incompressible Navier-Stokes equation:
Figure FDA0002939614840000023
in the formula: p represents pressure, μ represents kinematic viscosity;
(3) establishing turbulence model
Solving the simulation of the turbulence by adopting a Reynolds time-average stress method and based on a k-epsilon model;
the method decomposes the instantaneous velocity field into time-average quantity by Reynolds time-average stress method
Figure FDA0002939614840000024
And amount of pulsation
Figure FDA0002939614840000025
Figure FDA0002939614840000026
The decomposed instantaneous velocity field is brought into a momentum equation to obtain a time-averaged Navier-Stokes equation, and a new unknown quantity, namely a Reynolds stress term, is introduced at the same time
Figure FDA0002939614840000031
The form is as follows:
Figure FDA0002939614840000032
wherein u ', v ' and w ' respectively represent
Figure FDA0002939614840000033
The reynolds stress term is calculated using a vortex-viscous model based on the bucinnek approximation for the velocity components in the x, y and z directions as:
Figure FDA0002939614840000034
wherein
Figure FDA0002939614840000035
In the case of the kronecker symbol,
Figure FDA0002939614840000036
is the strain tensor, μtRepresenting the turbulent viscosity, k being the turbulent kinetic energy;
Figure FDA0002939614840000037
building a turbulence model based on a standard k-epsilon model to seal the flow equation, turbulence viscosity, mutIt is calculated that,
Figure FDA0002939614840000038
ε is the turbulent dissipation ratio, CμFor the empirical coefficient of turbulence, C for the standard k-epsilon modelμK is the turbulent kinetic energy, 0.09, which has a value of half the reynolds stress tensor,
Figure FDA0002939614840000039
(4) establishing a conjugate heat transfer model
Besides solving the flow equation, the computational fluid dynamics software also needs to solve the problems of convective heat transfer and heat conduction, namely solving the heat transfer problem in the solid and the coolant fluid at the same time, and the coupled heat transfer process is called conjugate heat transfer;
the established conjugate heat transfer model comprises a temperature control equation of the coolant and a temperature control equation in the solid domain; the temperature control equation of the coolant is as follows:
Figure FDA0002939614840000041
in the formula: t iscoolIs the temperature of the coolant, cpIs the specific heat capacity at constant pressure at the pressure p,
Figure FDA0002939614840000042
density of heat flow, q ″, transferred from the fuel rod cladding to the coolant'coolFor the volumetric heat release rate of the coolant, β is the volumetric thermal expansion coefficient, and Φ is the dissipation function:
Figure FDA0002939614840000043
in the formula:
Figure FDA0002939614840000044
is the tensor of friction;
sol denotes the solid domain, including fuel pellets and cladding, and the temperature control equation in the solid domain is:
Figure FDA0002939614840000045
in the formula: t issolIs the temperature of the solid domain, psolIs the density of the solid domain, and,
Figure FDA0002939614840000046
is the thermal conductivity in the solid domain, q'solIs the volumetric heat release rate of the solid domain;
the heat transfer equations of the fluid and the solid are solved by coupling the temperature and heat flux variables at the solid/fluid interface;
and step 3: establishing a corrosion product deposition calculation module
In calculating the deposition of corrosion products, the particles in the coolant considered include: boron, lithium, hydrogen, soluble nickel, soluble iron and particulate nickel ferrite; establishing a heat transfer model, a deposition kinetic model and a material transport model in corrosion deposition products, and comprising the following steps of:
(1) establishing a geometric model of the fuel rod according to physical characteristics of corrosion product deposition, and dividing a radial control body on the surface of the fuel rod in a corrosion product deposition calculation module for calculation of the corrosion product deposition;
(2) modeling heat transfer
The heat transfer model comprises a heat conduction equation in corrosion products and calculation of thermal diffusivity, density and effective specific heat capacity; the equation for thermal conductivity in corrosion deposition products is:
Figure FDA0002939614840000051
in the formula:
Figure FDA0002939614840000052
in the representation of corrosion products
Figure FDA0002939614840000053
The temperature at the time t at the location,
Figure FDA0002939614840000054
to represent
Figure FDA0002939614840000055
The thermal diffusivity at the time t at a location,
Figure FDA0002939614840000056
denotes a porosity of
Figure FDA0002939614840000057
Saturation temperature of coolant is TsatAt a temperature of TCRUDThe local thermal trap of (1);
thermal diffusivity of corrosion deposition products DtCalculated from the following formula:
Figure FDA0002939614840000058
wherein
Figure FDA0002939614840000059
In the representation of corrosion products
Figure FDA00029396148400000510
Temperature at position TCRUDThe coefficient of thermal diffusion at the time of use,
Figure FDA00029396148400000511
in the representation of corrosion products
Figure FDA00029396148400000512
Temperature at position TCRUDThe effective thermal conductivity at the time of the thermal treatment,
Figure FDA00029396148400000513
in the representation of corrosion products
Figure FDA00029396148400000514
Temperature at position TCRUDEffective specific heat capacity; effective coefficient of thermal conductivity
Figure FDA00029396148400000515
Coefficient of thermal conductivity of coolant
Figure FDA00029396148400000516
And thermal conductivity of corrosion deposition products
Figure FDA00029396148400000517
Porosity is carried out
Figure FDA00029396148400000518
The weight of the (c) is calculated,
Figure FDA00029396148400000519
Figure FDA00029396148400000520
in the products of corrosion deposition
Figure FDA00029396148400000521
The porosity of (d);
density of solid parts in corrosion products pcExpressing density ρ of corrosion deposition products per volume by porosity weightingbulk，
Figure FDA0002939614840000061
Similarly, corrosion deposition products are in place
Figure FDA0002939614840000062
At a temperature of TCRUDEffective specific heat capacity of
Figure FDA0002939614840000063
Is determined by the density ρ of the coolantcoolAnd density of solid portion of corrosion deposition product ρcTo weight-compute:
Figure FDA0002939614840000064
wherein
Figure FDA0002939614840000065
Denotes the coolant temperature TcoolThe specific heat capacity of (a) is,
Figure FDA0002939614840000066
the solid fraction temperature of corrosion products is TCRUDSpecific heat capacity of
(3) Establishing a deposition dynamics model
The deposition on the surface of the deposited layer of the corrosion product and the deposition at the internal pores are simultaneously considered in the surface deposition kinetic part; particles considered to be deposited on the surface of corrosion deposition products include nickel ferrite, nickel oxide and ferroferric oxide; the established deposition kinetic model comprises a deposition kinetic rate equation of each substance deposited on the surface and an equation for controlling the sedimentation of particles in pores;
the established deposition kinetic rate equation of each substance deposited on the surface is as follows:
Figure FDA0002939614840000067
wherein
Figure FDA0002939614840000068
Representing the concentration of particles in the solid region in the corrosion deposition product,
Figure FDA0002939614840000069
indicating the concentration of particles in the pore region of the corrosion deposition product,
Figure FDA00029396148400000610
representing the arrhenius rate coefficient of the particles in the pore region where the coolant is in an unsaporized state,
Figure FDA00029396148400000611
representing the Arrhenius rate coefficient, q ″, of particles in the pore region where the coolant is in the boiling stateCRUDIndicating boiling heat flux density in the corrosion deposition products,
Figure FDA00029396148400000612
for deposition losses due to turbulence, the values are the kinetic energy k of the turbulence and the tunable constant xeThe product of (a) and (b),
Figure FDA00029396148400000613
the particles deposited in the pores inside the corrosion deposition product include nickel ferrite, nickel oxide, ferroferric oxide, lithium tetraborate, lithium metaborate, boromagnesite and metaborate, and the equation governing the sedimentation of these particles in the pores is:
Figure FDA0002939614840000071
wherein A (η) is the surface area of the pores at which the porosity in the corrosion deposition product is η,
Figure FDA0002939614840000072
is the concentration of particles dissolved in the coolant,
Figure FDA0002939614840000073
is the solubility of the particles, calculated by models of thermodynamics and solubility;
Figure FDA0002939614840000074
the arrhenius rate coefficient of the dissolved particles,
(4) establishing a material transport model
Establishing a material transport model comprising a soluble transport equation of particles:
Figure FDA0002939614840000075
in the formula
Figure FDA0002939614840000076
And
Figure FDA0002939614840000077
are defined as being, respectively, a,
Figure FDA0002939614840000078
Figure FDA0002939614840000079
Figure FDA00029396148400000710
where Δ L is the calculated radial length, Δ r is the radial thickness of the computational mesh, Dpart(TCRUD) The particles are at a temperature TCRUDThe coefficient of thermal diffusion at the time of use,
Figure FDA00029396148400000711
is the concentration of particles in the vapor generated by local boiling in the products of corrosion deposition, vvaporIs the steam flow velocity, vbIs the boiling velocity, the steam flow velocity and the boiling velocity being linked by conservation of mass, i.e.
ρvaporvvapor＝ρcoolvb
ρvaporIs the density of the steam;
and 4, step 4: establishing a reactor physical-thermal analysis-corrosion product deposition coupling calculation model
A simplified form of the coupling equation is given to account for each computation block input and output and the coupling variables between them;
nuclide concentration NjThe physical quantity comprises all related nuclides j, the composition and boron concentration of corrosion deposition products are provided by a corrosion deposition product calculation module, and the nuclide concentration N is input into a reactor physical calculation modulejNuclide microscopic cross section sigma, nuclide temperature T and coolant density rhocoolComposition is carried out; the operator N expresses the neutron transport equation to be solved, and the local neutron fluence rate phi and the critical coolant boron concentration are obtained
Figure FDA0002939614840000081
As shown in the following formula:
Figure FDA0002939614840000082
the power density operator P represents the distribution of the power density calculated by the neutron fluence rate,
q″′＝P(φ)
the thermodynamic hydraulic analysis model established in computational fluid dynamics software mainly comprises a Navier-Stokes equation and a temperature equation for solving the conjugate heat transfer, wherein an operator F represents the Navier-Stokes equation, an operator H represents the temperature equation, and the two parts jointly solve the flow and heat transfer characteristics in the assembly;
by the distribution q' ″ of the input power density, the coolant temperature TcoolAnd the thermal resistance gamma of corrosion deposition products, and calculating the heat flow density q' and the temperature T of the surface of the hullsolid，
(Tsolid,q″)＝H(q″′,Tcool,Γ)
After the heat current density q' on the surface of the cladding is input, the temperature T of the coolant is obtained by solving the Navier-Stokes equationcoolAnd density ρcoolAnd turbulent kinetic energy k near the surface of the cladding;
(Tcool,ρcool,k)＝F(q″)
the reactor physics calculating module and the thermal hydraulic analysis calculating module pass through q', Tsolid、TcoolAnd ρcoolAre coupled together;
in the corrosion deposition product calculation module, the input comprises the cladding heat flow density q', and the coolant temperature T of the contact section of the corrosion deposition product and the coolantcoolTurbulent kinetic energy k, concentration of boron in coolant
Figure FDA0002939614840000091
And rate of neutron-boron reaction RBThe output includes the thermal resistance gamma of corrosion deposition product and the concentration of nuclide in the composition
Figure FDA0002939614840000092
The calculation is shown as follows, operator C representing the module for corrosion product depositionAnd (3) solving:
Figure FDA0002939614840000093
the corrosion deposition product calculation module and the thermal hydraulic analysis calculation module calculate the temperature T of the contact section of the corrosion deposition product and the coolant through the cladding heat flow density q ″coolThe turbulent kinetic energy k and the corrosion deposition product thermal resistance gamma are coupled together; the corrosion deposition product calculation module and the reactor physical calculation module pass the concentration of boron in the coolant
Figure FDA0002939614840000094
Reaction rate of neutrons with boron RBAnd nuclide concentration in corrosion deposition product composition
Figure FDA0002939614840000095
Are coupled together;
and 5: the steps of solving the coupling solution by carrying out reactor physical-thermal analysis-corrosion product deposition coupling calculation are as follows:
(1) setting an initial calculation working condition for a reactor physical calculation module, and calculating to obtain the initial power density distribution of a reactor assembly according to the set condition; based on a grid mapping technology, firstly carrying out interpolation processing on discrete physical quantities of each node obtained by calculation of an original grid to obtain spatial continuous distribution of the physical quantities, then obtaining corresponding physical quantity values according to spatial coordinates of each node of a target grid based on the distribution, realizing grid mapping of calculation results, thereby completing data exchange between modules, developing a coupling interface module for different modules, transmitting power distribution obtained by reactor physical calculation to a thermal analysis calculation module through the coupling interface module, setting distribution of an initial coolant flow field and a temperature field obtained by the thermal analysis calculation, carrying out calculation, and obtaining fuel surface heat flow density, cladding surface temperature, coolant temperature and density, fuel temperature and turbulent kinetic energy through calculation;
(2) transmitting the calculated boron concentration, neutron flux, heat flux density, cladding surface temperature, coolant temperature and turbulent kinetic energy to a corrosion product deposition calculation model by a coupling interface module, updating the setting, and calculating to obtain the component composition of the corrosion deposition product and the thermal resistance of the deposit;
(3) transferring the coolant temperature, density and fuel temperature calculated by the thermal analysis and calculation module to a reactor physical calculation module through a coupling interface module, transferring the component ingredients calculated by the corrosion product deposition calculation module to the reactor physical calculation module through the coupling interface module, and obtaining the component power density, boron concentration and neutron flux through the reactor physical calculation module;
(4) the calculated power density distribution and sediment thermal resistance of the assembly are transmitted to a thermal analysis and calculation module through a coupling interface module, and a flow field and a temperature field of the updated assembly are calculated;
(5) and (4) judging whether residual errors of the coolant flow rate, the coolant temperature and the fuel rod internal temperature meet a convergence criterion, namely are smaller than a preset residual error value, and if not, repeating the steps from (2) to (4) until convergence.
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