CN110390444B - Nuclear fuel circulation facility UF 6 Accident leakage consequence evaluation and calculation method - Google Patents

Nuclear fuel circulation facility UF 6 Accident leakage consequence evaluation and calculation method Download PDF

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CN110390444B
CN110390444B CN201810337976.6A CN201810337976A CN110390444B CN 110390444 B CN110390444 B CN 110390444B CN 201810337976 A CN201810337976 A CN 201810337976A CN 110390444 B CN110390444 B CN 110390444B
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崔慧玲
姚仁太
辛存田
张新骞
张芳
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China Institute for Radiation Protection
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Abstract

The invention belongs to the technical field of nuclear safety evaluation, and relates to a nuclear fuel circulation facility UF 6 An accident leakage consequence evaluation and calculation method. The evaluation calculation method sequentially comprises the following steps: (1) determining source item parameters: calculating source item parameters according to actual working conditions, or knowing or assuming the source item parameters; (2) performing diffusion calculation in an atmospheric environment under different accident situations according to the source item parameters determined in the step (1); (3) UF 6 And calculating the health effect of the accident consequence. The assessment calculation method of the invention can simply and quickly carry out the special UF 6 The accident leakage consequence evaluation calculation is more reliable.

Description

Nuclear fuel circulation facility UF 6 Accident leakage consequence evaluation and calculation method
Technical Field
The invention belongs to the technical field of nuclear safety evaluation, and relates to a nuclear fuel circulation facility UF 6 An accident leakage consequence evaluation and calculation method.
Background
Involving UF 6 Nuclear fuel recycling facilities for accident leakage include uranium conversion plants, fuel assembly plants, uranium enrichment plants, and depleted uranium storage farms. The nuclear fuel circulation facility may be provided during operationFailure or misoperation occurs 6 May be a nuclear fuel recycling facility such as a uranium enrichment plant pipeline that has broken down to emit UF-containing gas 6 Or the pressure vessel is broken to release UF 6 Also in the long-term storage of depleted uranium, there is a DUF caused by breakage of the vessel 6 Risk of leakage), UF after leakage 6 Immediately reacts with water in the environment to generate UO 2 F 2 And HF. Soluble uranium is chemically toxic and radioactive to humans, and inhalation of HF can cause chemical erosion and burning of the lungs and mucous membranes.
UF 6 Has been a potentially significant risk to nuclear fuel recycling facilities, understanding UF 6 Hazardous substances such as UF produced after release 6 、UO 2 F 2 And HF distribution in the environment, are very important and critical for safety measures, emergency planning, and outcome assessment.
UF 6 Having particular chemical and radiological hazards, especially chemical hazards, so UF 6 The accident consequence research method mainly includes numerical simulation, that is, the concentration distribution and change of each substance are predicted by simulation calculation, and the health effect is calculated (see U.S. Environmental Protection Agency (USEPA)]Research Triangle Park, North Carolina, EPA-454/R-92-024,1992). UF was developed abroad since the 70 s of the last century 6 Accident consequences study, on UF in the last two decades 6 The study Of the accident consequence calculation method was not much developed, but was still based on two main Models, namely the RASCAL model (see U.S. nucleic Regulation Commission Of science Of nucleic Security and Induction Response, RASCAL 3.0.5: Description Of Models and Methods, Washington DC 20555- 6 Model (see Hanna S.R., ChangJ.C., and zhang J.X (1995) Technical documentation of HGSYSTEM/UF) 6 model.Report 1331,EARTH TECH,196Baker Ave.,Concord,Massachusetts 01742)。
The RASCAL model is an emergency model developed and used by the American Nuclear Association, and includes UF 6 Computing module of. At UF 6 In the calculation module, for an accident source item, a release share and a release rate are directly set after a position type of a storage tank or a leakage valve is selected; after the gravity subsidence and chemical thermodynamic transformation were calculated in the diffusion calculation, a conventional gaussian model was used for the diffusion calculation.
The HGSYSTEM model is a chemical dangerous article accident calculation model developed by Shell company of America, and Hanna in 1994 improves the HGSYSTEM model and adds UF 6 The specific chemical thermodynamic calculation of (A) establishes HGSYSTEM/UF 6 And (4) calculating the model. HGSYSTEM/UF 6 Because of the calculation model based on general chemical dangerous goods, the model structure is complex, and meanwhile, a plurality of artificial assumptions also exist for source items.
The two models are both foreign development models, and the main problems of the calculation method are as follows:
1) for accident source items, source item parameters are directly set according to an accident scene, so that the calculation of leakage consequences has great uncertainty;
2) in the diffusion calculation, after the characteristics of heavy gas are calculated, the diffusion calculation is carried out by adopting a traditional Gaussian mode, the gravity diffusion and the Gaussian diffusion are artificially divided into two diffusion stages, and the actual diffusion process is not met;
3) RASCAL and HGSYSTEM/UF 6 Are not UF 6 The dedicated calculation model has a complex overall structure, and is inconvenient to carry out simple and quick UF 6 And calculating the accident consequence.
Disclosure of Invention
It is a primary object of the present invention to provide a nuclear fuel cycle facility UF 6 The accident leakage consequence evaluation and calculation method can simply and quickly carry out the special UF 6 The accident leakage consequence evaluation calculation is more reliable.
To achieve this, in a basic embodiment, the present invention provides a nuclear fuel recycling facility UF 6 The accident leakage consequence evaluation and calculation method sequentially comprises the following steps:
(1) determining source item parameters: calculating source item parameters according to actual working conditions, or knowing or assuming the source item parameters;
(2) performing diffusion calculation in an atmospheric environment under different accident situations according to the source item parameters determined in the step (1);
(3)UF 6 and calculating the health effect of the accident consequence.
The invention refers to a calculation method related to chemical accidents, establishes a complete UF composed of a source item calculation model and a diffusion calculation model based on the actual condition of nuclear fuel circulation in China 6 According to the accident leakage consequence calculation method, two calculation models can also be independently operated respectively. The invention calculates UF by using fluid mechanics and thermodynamics method 6 Accident source item parameters and physical process of smoke cloud diffusion after accidents are calculated, and UF is introduced into calculation 6 Specific chemical thermodynamic process, and the calculation result outputs UF 6 The concentration distribution and the health effect of each pollutant after accident leakage can be applied to the fields of accident consequence, safety evaluation and emergency plan application.
In a preferred embodiment, the present invention provides a nuclear fuel recycling facility UF 6 The accident leakage consequence evaluation calculation method is characterized in that in the step (1), the determined source item parameters comprise UF 6 Release rate (leak rate), two-phase fraction of the plume, plume density, and/or plume temperature.
In a more preferred embodiment, the present invention provides a nuclear fuel recycling facility UF 6 In the accident leakage consequence evaluation and calculation method, in the step (1), the source item parameters are calculated and determined respectively under three conditions, wherein the three conditions are UF respectively 6 Sustained release of liquid, UF 6 Sustained release of gas and copious UF 6 The liquid is released instantaneously.
In a more preferred embodiment, the present invention provides a nuclear fuel recycling facility UF 6 In the accident leakage consequence evaluation and calculation method, in the step (1), the source parameter is determined for calculation, and the input actual working condition parameters comprise container temperature, container pressure, container loading capacity and container damage size.
In a more preferred embodimentIn one embodiment, the present invention provides a nuclear fuel cycle facility UF 6 Accident leakage consequence evaluation calculation method, wherein in step (1), UF 6 Under the condition of liquid sustained release, the calculation formulas of the source term parameters are respectively as follows:
Figure BDA0001629775900000031
Figure BDA0001629775900000032
Figure BDA0001629775900000033
wherein:
t is the temperature (K) of the released gas plume;
q is liquid UF 6 Release rate (kg/s);
c is a constant;
a is the leakage area (m) 2 )；
ρ l Is UF 6 Liquid Density (kg/m) 3 )；
P r ,P a Respectively the pressure in the container and the ambient pressure (Pa);
g is gravity acceleration (g is 9.8m/s 2);
h is a pressure head (m);
f is UF in the tobacco mass 6 Fraction of gaseous form;
m l is an initial UF 6 Total mass of liquid (kg);
λ f ，λ s are respectively UF 6 Heat of solution and UF for solid-liquid conversion 6 Heat of sublimation for solid-gas conversion (J/kg);
c pl ，c ps ，c pv are respectively UF 6 Constant pressure heat capacity (J/kg-K) of liquid, solid and gas phases;
T r ,T s ,T t are respectively UF 6 Vessel temperature, UF 6 Sublimation temperature, UF 6 Triple point temperature (K);
rho is the density (kg/m) of the gas-solid mixed smoke mass after initial release and flash evaporation 3 )；
w is UF 6 Total mass (kg);
Figure BDA0001629775900000041
respectively at the sublimation point UF 6 Gas and solid density (kg/m) 3 )。
In a more preferred embodiment, the present invention provides a nuclear fuel recycling facility UF 6 Accident leakage consequence evaluation calculation method, wherein in step (1), UF 6 In the case of sustained release of gas, the determination of each of the source parameters is as follows:
(1) calculating the saturated vapor pressure when the gas phase and the condensed phase in the container are balanced when an accident occurs, namely the pressure of the storage tank,
Figure BDA0001629775900000042
wherein:
T r is UF 6 The temperature (K) at which the two phases equilibrate in the vessel;
P r is the pressure (Pa) of the tank,
(2) the gas flow pressure is calculated according to the formula below, with leakage being choked flow if the gas flow pressure is greater than ambient pressure, otherwise subcritical flow,
Figure BDA0001629775900000043
wherein:
for UF6, γ ═ 1.07;
p is a gas flow pressure (Pa),
(3) for the choked flow, the calculation formulas of the source term parameters are respectively as follows,
Figure BDA0001629775900000051
T＝T r [1-(0.85)(γ-1)/(γ+1)]
Figure BDA0001629775900000052
wherein:
q is UF 6 Release rate (kg/s);
c is a constant;
a is the leakage area (m) 2 )；
P r Is the tank pressure (Pa);
for UF6, γ ═ 1.07;
m is UF 6 Molecular weight (g/mol);
r is an ideal gas constant (8.314JK- 1 mol- 1 )；
T r Is UF 6 Tank temperature (K);
t is the temperature (K) of the released gas plume;
ρ is the density of the leaked UF6 smoke mass (kg/m) 3 )，
(4) For subcritical flow, the calculation formula of each source term parameter is as follows,
Figure BDA0001629775900000053
T＝2T r /[1+(1+4ET r ) 1/2 ]
E＝[1/(2c p )][QR/(PMA)] 2
Figure BDA0001629775900000054
wherein:
q is UF 6 Release rate (kg/s);
c is a constant;
a is let outArea of leakage (m) 2 )；
ρ v Is UF 6 Gas density (kg/m) in the storage tank 3 )；
P r Is UF 6 A gas pressure (Pa) within the storage tank;
T r is UF 6 The temperature (K) of the gas in the storage tank;
tleak plume temperature (K);
e is a correction function;
m is UF 6 Molecular weight (g/mol);
r is an ideal gas constant (8.314 JK) -1 mol -1 )；
c p Constant pressure heat capacity (Jkg) -1 K -1 )；
ρ * Is a leaked UF 6 Density of tobacco mass (kg/m) 3 )。
In a more preferred embodiment, the present invention provides a nuclear fuel recycling facility UF 6 Accident leakage consequence evaluation calculation method, wherein in step (1), a large amount of UF 6 In case of instantaneous release of liquid, all UF in the tank 6 The liquid is released all over for a short time, at which time UF 6 The smoke mass temperature is the triple point temperature (T-329.4K), and the density and the gas phase portion of the smoke mass formed after release are calculated according to the following formulas:
Figure BDA0001629775900000061
Figure BDA0001629775900000062
wherein:
m l is an initial UF 6 Total mass of liquid (kg);
λ f ，λ s are respectively UF 6 Heat of solution and UF for solid-liquid conversion 6 Heat of sublimation for solid-gas conversion (J/kg);
c pl ，c ps ，c pv are respectively provided withIs UF 6 Constant pressure heat capacity (J/kg-K) of liquid, solid and gas phases;
T r ,T s ,T t are each UF 6 The temperature of the container, the sublimation temperature and the triple point temperature (K);
ρ is UF 6 Density of tobacco mass (kg/m) 3 )。
In a more preferred embodiment, the present invention provides a nuclear fuel recycling facility UF 6 In the accident leakage consequence evaluation and calculation method, in the step (2), in order to carry out the diffusion calculation, the parameters needing to be input are divided into two types, one type is source parameter comprising release rate, smoke mass density, smoke mass temperature and two-phase fraction, and the other type is environmental meteorological parameter comprising wind speed, temperature, humidity, stability and surface roughness.
In a more preferred embodiment, the present invention provides a nuclear fuel recycling facility UF 6 In the accident leakage consequence evaluation calculation method, in the step (2), a main model and four sub models are established to perform diffusion calculation, wherein the calculation equation set of the main model is as follows:
(1) for UF 6 The continuous release (vertical or horizontal jet) scene, the main equation set of one-dimensional conservation of fluid mechanical quality, momentum and energy is established (only a downwind distance variable x is considered),
Figure BDA0001629775900000071
Figure BDA0001629775900000072
Figure BDA0001629775900000073
d(ρuBhu)/dx+0.5a g gd[(ρ-ρ a )Bh 2 ]/dx＝ρ a (v e h+w e B)u a +f u
d(ρuBhv g )/dx＝g(ρ-ρ a )h 2 +f vg
d(ρuBhw c )/dx＝-g(ρ-ρ a )Bh+f w
and the following auxiliary equations providing the required calculation parameters for the main equation set calculation,
u(dB/dx)＝(ρ a /ρ)v e +v g
u(db/dx)＝v g ·b/B
u(dz c /dx)＝w c
ρ＝ρ a ·T a /[α·T+γ·T a ]
solving the main equation set;
(2) for UF 6 Instantaneous mass release scene, establishing a main equation set of fluid mechanical mass, momentum and energy volume average conservation (only considering time variable t),
Figure BDA0001629775900000074
Figure BDA0001629775900000075
Figure BDA0001629775900000076
(ρB x hu)dB y /dt＝ρ a [(v ex B y +v ey B x )h+w e B x B y ]u a +B x f u
(ρB x hu g )dB y /dt＝g(ρ-ρ a )h 2 B x +B x f vg
(ρB x hv g )dB y /dt＝g(ρ-ρ a )h 2 B y +B x f vg
(ρB x hw c )dB y /dt＝-g(ρ-ρ a )hB x B y +B x f w
and the following auxiliary equations providing the required calculation parameters for the main equation set calculation,
dB y /dt＝(ρ a /ρ)v ey +v g
db y /dt＝v g ·b y /B y
dB x /dt＝(ρ a /ρ)v ex +u g
db x /dt＝u g ·b x /β x
u(dz c /dt)＝w c
ρ＝ρ a ·T a /[α·T+γ·T a ]
solving the main equation set;
wherein:
rho is the density of the mixed tobacco mass (kg/m) 3 )；
u is the wind speed (m/s);
b, h are the width and height (m) of the tobacco mass respectively;
Figure BDA0001629775900000081
for mixing UF in the tobacco mass 6 Mass concentration at which no chemical reaction occurs;
Figure BDA0001629775900000082
to release UF 6 Density of tobacco mass (kg/m) 3 )；
Figure BDA0001629775900000083
Is UF 6 The vertical ejection speed (kg/s) of the tobacco mass;
Figure BDA0001629775900000084
is the width of the source (m);
ρ a is the density of ambient air (kg/m) 3 )；
v e ,w e Horizontal and vertical air entrapment rates (m/s), respectively;
Figure BDA0001629775900000085
respectively the specific heat capacity of the mixed smoke mass, the specific heat capacity of air and UF 6 Specific heat capacity of gas (J/kg) -1 K -1 )；
Δ H is the heat of chemical reaction (J/kmol);
a g ,v g the gravity wave velocities (m/s) of the horizontal downwind direction and the transverse wind direction of the tobacco mass respectively;
g is the acceleration of gravity (9.8 m/s) 2 )；
f u ,f vg ,f w The friction force in downwind direction, transverse wind direction and vertical direction are respectively;
w c is the vertical velocity (m/s) of the mass;
B x ,B y the widths (m) of the mixed tobacco mass in the x direction and the y direction are respectively;
v ex ,v ey air mixing entrapment rates (m/s) in x and y directions, respectively;
b,b x ,b y respectively the width parameters of the mixed tobacco mass;
z c is a height parameter of the tobacco mass;
alpha and gamma are respectively the molecular weight calculation and density calculation parameters of the mixed smoke group,
the calculation formulas of the four submodels are as follows:
(1) wind profile model
du a /dz＝(u a */kz)·Φ m (z/L)·g(z/H)
Φ m (z/L)＝1+5·L- 1 ·z/(1+z/z L (s)
z L (s)＝1+0.8·(s-4)
g(z/H)＝1-z/130·2 (7-s)
Wherein:
u a ambient wind speed (m/s);
u a* ambient friction speed (m/s);
k is von Karman constant;
z is the height (m);
Φ m is a Moore function;
l is the Moore length (m);
h is the mixed layer height (m);
z L (s) a stability parameter;
s is the stability (1-6),
(2) air entrainment rate model
Figure BDA0001629775900000091
g(h/H)＝1-h/H
Φ h (h/L)＝1+5·h/L,(L≥0)
Φ h (h/L)＝1/(1-16·h/L) 1/2 ,(L＜0)
Figure BDA0001629775900000092
Figure BDA0001629775900000093
Wherein:
w e is the vertical curl ratio (m/s);
a and k are constants respectively;
g (H/H) is a function of the height of the mixed layer;
h is height (m);
h is the mixed layer height (m);
Φ h (h/L) is a Moore height function;
v ey air entrainment rate in horizontal y-direction (m/s);
v ex air entrapment rate (m/s) in horizontal x-direction;
v a is a horizontal velocity term;
v j ,v s in the form of the vertical velocity term,
(3) chemical thermodynamic model
Figure BDA0001629775900000101
Figure BDA0001629775900000102
Figure BDA0001629775900000103
Figure BDA0001629775900000104
ΔH air ＝0.24037·ΔT c
Figure BDA0001629775900000105
Wherein:
ΔH plume enthalpy of the mixed smoke mass (kJ/mol);
Figure BDA0001629775900000106
is UF 6 Enthalpy of component (kJ/mol);
Figure BDA0001629775900000107
is UO 2 F 2 Enthalpy of component (kJ/mol);
Figure BDA0001629775900000108
is HF-H 2 Enthalpy of O system component (kJ/mol);
ΔH air is the enthalpy (kJ/mol) of the air component;
H rxn heat evolved for chemical reactions (kJ/mol);
T r ,T f ,T c respectively, temperature (R, F, C);
z P,T is UF6 gas compressibility;
Figure BDA0001629775900000109
respectively the share of different components of HF;
Figure BDA00016297759000001010
mass (kg) of UF 6;
Figure BDA00016297759000001011
molecular weight of UF6 (g/mol),
(4) tobacco cluster lifting model
For initial high density UF 6 The discharge, lift calculation is as follows:
Figure BDA00016297759000001012
R v ＝w s /u a
S g ＝ρ s /ρ a
F r ＝w s /[g·D s ·(ρ s -ρ a )/ρ a ] 1/2
D s ＝(4/π 1/2 )·B s
wherein:
h pr is the elevation height (m) of the mixed mass of tobacco;
R v is the wind shear ratio;
S g is the density ratio of the tobacco mass;
F r is a function of gravity;
w s is UF 6 Release speed (m/s);
u a ambient wind speed (m/s);
ρ s ,ρ a are respectively UF 6 Gas density and ambient air density (kg/m) 3 )；
g is the acceleration of gravity (9.8 m/s) 2 )；
D s ,B s Respectively the width parameter of the source and the width (m) of the source,
the calculation output result of the main model and the four submodels is the downwind UF 6 、UO 2 F 2 HF concentrations at different distances.
In a more preferred embodiment, the present invention provides a nuclear fuel recycling facility UF 6 In the step (3), the parameters of health effect calculation include the total integrated concentration of uranium, the inhaled uranium amount, the effective dose to be integrated and the HF hour equivalent concentration in the lung, and the calculation formula is as follows:
Figure BDA0001629775900000111
Figure BDA0001629775900000112
H E,50 ＝m u ·D u-235 ·A u ·DCF E,50
c 1HF ＝c HF (t)(t/3600) 1/2
wherein:
Figure BDA0001629775900000113
respectively, the integrated concentration of total uranium (mg-s/m) 3 )、UF 6 Concentration (mg/m) 3 )、 UO 2 F 2 Concentration of (mg/m) 3 )；
m u (x) Is the inhaled quantity of uranium (mg);
φ inh is the respiration rate (m) 3 /s)；
H E,50 Is an effective dose to be accumulated (rem);
D u-235 is the abundance of uranium;
A u specific activity of uranium (μ Ci/g);
DCF E,50 is the effective dose coefficient to be integrated (rem/. mu.Ci);
c 1HF at 1 hour equivalent concentration in the lung (mg/m) 3 )；
t is the irradiation duration(s).
The present invention has the advantageous effect that the nuclear fuel cycle facility UF of the present invention is utilized 6 The accident leakage consequence evaluation and calculation method can simply and quickly carry out the special UF 6 The accident leakage consequence evaluation calculation is more reliable.
The beneficial effects of the invention are embodied in the following aspects:
1) calculating source item parameters of thermodynamics and hydrodynamics calculation based on actual working conditions;
2) based on basic fluid-mechanical equations and introducing UF 6 The exclusive chemical thermodynamic calculation and the fluid mechanics calculation method truly reflect the physical process of the diffusion of the pollutants in the atmosphere;
3) calculate UF 6 Health effects of accidental leaks.
The invention establishes a complete UF including source and diffusion calculations 6 The accident consequence evaluation calculation method, the source item calculation model and the diffusion calculation model can respectively operate independently or integrally according to actual needs. The whole calculation model has clear theoretical framework and concise and efficient calculation, and compared with other existing models, the accurate calculation of the source item parameters is increased, so that the uncertainty of the source item is reduced. In addition, the invention does not depend on foreign introduction models, and establishes the UF developed by the invention 6 Calculation model for UF 6 The improvement of the study capability of accident consequence. Further verification through experimental data shows that the assessment calculation method is accurate and effective UF 6 And (3) an evaluation calculation method of accident leakage consequences. The evaluation calculation method can be applied to the fields of accident consequence, safety evaluation and emergency plan application.
Drawings
FIG. 1 is an exemplary inventive nuclear fuel cycle facility UF 6 And (3) a flow chart of the accident leakage consequence evaluation calculation method.
FIG. 2 is an exemplary nuclear fuel cycle facility UF of the present invention 6 And in the accident leakage consequence evaluation and calculation method, a calculation flow chart of the step of calculating the source item parameters according to the actual working conditions is shown.
FIG. 3 is an exemplary inventive nuclear fuel cycle facility UF 6 And (3) a calculation flow chart of a step of 'diffusion calculation in an atmospheric environment' in the accident leakage consequence evaluation calculation method.
FIG. 4 is an exemplary nuclear fuel cycle facility UF of the present invention 6 "UF" in calculation method for evaluating accident leakage consequence 6 Calculating the health effect of the accident consequence.
FIG. 5 is a model of the invention in a specific embodiment (UF) 6 ) And HGSYSTEM/UF 6 And (4) comparing deviation of the RASCAL model.
Detailed Description
Exemplary inventive Nuclear Fuel cycle facility UF 6 The flow of the accident leakage consequence evaluation and calculation method is shown in fig. 1-4, and the specific implementation process is as follows:
(one) source item parameter calculation determination
According to the actual working condition, the source parameter calculation scene comprises three accident scenes, namely UF 6 Sustained release of liquid, UF 6 Sustained release of gas, high UF 6 The liquid is released instantaneously. Calculating the model input conditions as actual working condition conditions (actual accident occurrence conditions) including container temperature, pressure, loading capacity and damage size; the output parameters are source characteristics including release rate (leak rate), two-phase fraction of the soot mass, soot mass density, and soot mass temperature.
1、UF 6 Calculation and determination of source parameter during liquid sustained release
UF at ambient temperature 6 Stored in solid form in specially-made cylinders, heated when required for transport to another processing unit (temperature and pressure near or above triple point, UF) 6 In liquid form) where a leak occurs if there is a break in the cylinder or valve of the delivery passage. When the leakage is under the liquid surface, the liquid is released and flash evaporation is carried out immediately after decompression (assuming an isentropic process) to generate UF 6 The gas and solid particles mix the plume. The solid particles sublime immediately (ignoring the effect of sublimation on plume density), and the plume temperature drops to UF 6 Sublimation point at ambient atmospheric pressure (329.4K). The main calculation formula is as follows:
calculating the fraction of the gas phase and the solid phase after flash evaporation and calculating the release rate of each phase according to the heat conservation, wherein for liquid leakage in the downward leakage direction, the release rate only calculates the fraction of the gas phase, UF 6 The solid particles are assumed to be deposited entirely on the ground.
Figure BDA0001629775900000131
Figure BDA0001629775900000132
Figure BDA0001629775900000133
Wherein:
t is the temperature (K) of the released gas plume;
q is liquid UF 6 Release rate (kg/s);
c is a constant;
a is the leakage area (m) 2 )；
ρ l Is UF 6 Liquid Density (kg/m) 3 )；
P r ,P a Respectively the pressure in the container and the ambient pressure (Pa);
g is gravity acceleration (g is 9.8 m/s) 2 )；
h is a pressure head (m);
f is UF in the tobacco mass 6 Fraction of gaseous form;
m l is an initial UF 6 Total mass of liquid (kg);
λ f ，λ s are respectively UF 6 Heat of solution and UF for solid-liquid conversion 6 Heat of sublimation for solid-gas conversion (J/kg);
c pl ，c ps ，c pv are respectively UF 6 Constant pressure heat capacity (J/kg-K) of liquid, solid and gas phases;
T r ,T s ,T t are each UF 6 Vessel temperature, UF 6 Sublimation temperature, UF 6 Triple point temperature (K);
rho is the density (kg/m) of the gas-solid mixed smoke mass after initial release and flash evaporation 3 )；
w is UF 6 Total mass (kg);
Figure BDA0001629775900000141
respectively at the sublimation point UF 6 Gas and solid density (kg/m) 3 )。
2、UF 6 Calculation and determination of source parameter during gas sustained release
UF 6 UF in solid or liquid form in pressure vessels, when damage is present on the liquid or solid surface and on the pipes or pressure relief valves 6 The gas leaks. The method comprises the steps of firstly calculating saturated vapor pressure when gas phase and condensed phase in a container are balanced during an accident, judging the flow state of leakage according to the pressure, and selecting different formulas to calculate the release rate, the smoke mass density and the temperature according to different flow states ('choked flow' or 'subcritical flow'). The main calculation formula is as follows:
(1) calculating the saturated vapor pressure when the gas phase and the condensed phase in the container are balanced during the accident, namely the pressure of the storage tank,
Figure BDA0001629775900000142
wherein:
T r is UF 6 Two phases in the container are flatTemperature at equilibrium (K);
P r is the pressure (Pa) of the reservoir.
(2) Calculating the gas flow pressure according to the following formula, and judging whether the leakage is a choked flow or a subcritical flow,
Figure BDA0001629775900000151
wherein:
for UF 6 ，γ＝1.07；
P is a gas flow pressure (Pa);
if the flow pressure is greater than ambient pressure, the leak is choked flow, otherwise subcritical flow.
(3) For the choked flow, the calculation formula of each source term parameter is respectively as follows,
Q＝cAP r [(γM/RT r )(2/(γ+1)) (γ+1)/(γ-1) ] 1/2
T＝T r [1-(0.85)(γ-1)/(γ+1)]
Figure BDA0001629775900000152
wherein:
q is UF 6 Release rate (kg/s);
c is a constant;
a is the leakage area (m) 2 )；
P r Is the tank pressure (Pa);
for UF6, γ is 1.07;
m is UF 6 Molecular weight (g/mol);
r is an ideal gas constant (8.314 JK) -1 mol -1 )；
T r Is UF 6 Tank temperature ((K);
t is the temperature (K) of the released gas plume;
ρ is the density of the leaked UF6 smoke mass (kg/m) 3 )。
(4) For subcritical flow, the calculation formula of each source term parameter is as follows,
Q＝cA{2ρ v P r γ/(γ-1)[(P a /P r ) 2/γ -(P a /P r ) (γ+1)/γ ]} 1/2
T＝2T r /[1+(1+4ET r ) 1/2 ]
E＝[1/(2c p )][QR/(PMA)] 2
Figure BDA0001629775900000153
wherein:
q is UF 6 Release rate (kg/s);
c is a constant;
a is the leakage area (m) 2 )；
ρ v Is UF 6 Density of gas in storage tank (kg/m) 3 )；
P r Is UF 6 A gas pressure (Pa) within the storage tank;
T r is UF 6 The temperature (K) of the gas in the storage tank;
tleak plume temperature (K);
e is a correction function;
m is UF 6 Molecular weight (g/mol);
r is an ideal gas constant (8.314 JK) -1 mol -1 )；
c p Is constant pressure heat capacity (Jkg) -1 K -1 )；
ρ * Is UF of leaks 6 Density of tobacco mass (kg/m) 3 )。
3. Large amount of UF 6 Calculation and determination of source parameter during liquid instantaneous release
Due to UF 6 Loading overload, cylinder burst due to severe thermal expansion during heating, UF 6 The liquid is instantaneously released and flashed into gas and solid particulates, where UF forms a large amount of white smoke 6 The smoke mass temperature is the triple point temperature (T-329.4K), and needs to be calculatedThe density and gas phase fraction of the formed smoke mass after release,
Figure BDA0001629775900000161
Figure BDA0001629775900000162
wherein:
m l is an initial UF 6 Total mass of liquid (kg);
λ f ，λ s are respectively UF 6 Heat of solution and UF for solid-liquid conversion 6 Heat of sublimation for solid-gas conversion (J/kg);
c pl ，c ps ，c pv are respectively UF 6 Constant pressure heat capacity (J/kg) of liquid, solid and gas phases -1 K -1 )；
T r ,T s ,T t Are each UF 6 The temperature of the container, the sublimation temperature and the triple point temperature (K);
ρ * is UF 6 Density of tobacco mass (kg/m) 3 )。
(II) diffusion calculation in atmospheric environment
1. Main model for diffusion calculation
The diffusion calculation needs to input source item parameters and environmental meteorological conditions. The atmospheric diffusion model takes the calculation result of the source item model as the source item parameter input, different diffusion calculations are selected according to accident types, and the diffusion calculation is divided into two situations for calculation, wherein one situation is UF 6 Sustained release (vertical or horizontal spray), the other being UF 6 Is released in large amount instantaneously. Due to UF 6 The heavy gas effect and the chemical thermodynamic process of the method are all in a short-distance range (a range of several kilometers) of atmospheric diffusion, the space-time range is small, the considered environmental conditions are constant, and the environmental meteorological conditions required to be input during diffusion calculation are as follows: ambient temperature, wind speed, humidity, stability and surface roughness.
(1) For UF 6 Sustained release scenario, establishing hydrodynamic qualityMomentum, energy one-dimensional conservation equation set (only considering downwind distance x variable),
Figure BDA0001629775900000171
Figure BDA0001629775900000172
Figure BDA0001629775900000173
d(ρuBhu)/dx+0.5a g gd[(ρ-ρ a )Bh 2 ]/dx＝ρ a (v e h+w e B)u a +f u
d(ρuBhv g )/dx＝g(ρ-ρ a )h 2 +f vg
d(ρuBhw c )/dx＝-g(ρ-ρ a )Bh+f w
establishing an auxiliary equation, providing required parameters for the calculation of the conservation equation set,
u(dB/dx)＝(ρ a /ρ)v e +v g
u(db/dx)＝v g ·b/B
u(dz c /dx)＝w c
ρ＝ρ a ·T a /[α·T+γ·T a ]
the conservation equation set and the auxiliary equation form a main model for calculating the sustained release diffusion,
(2) for UF 6 Instantaneous mass release scene, establishing fluid mechanics mass, momentum, energy volume average conservation equation system (only considering time variable t),
Figure BDA0001629775900000174
Figure BDA0001629775900000175
Figure BDA0001629775900000176
(ρB x hu)dB y /dt＝ρ a [(v ex B y +v ey B x )h+w e B x B y ]u a +B x f u
(ρB x hu g )dB y /dt＝g(ρ-ρ a )h 2 B x +B x f vg
(ρB x hv g )dB y /dt＝g(ρ-ρ a )h 2 B y +B x f vg
(ρB x hw c )dB y /dt＝-g(ρ-ρ a )hB x B y +B x f w
establishing an auxiliary equation, providing required parameters for the calculation of the conservation equation set,
dB y /dt＝(ρ a /ρ)v ey +v g
db y /dt＝v g ·b y /B y
dB x /dt＝(ρ a /ρ)v ex +u g
db x /dt＝u g ·b x /β x
u(dz c /dt)＝w c
ρ＝ρ a ·T a /[α·T+γ·T a ]
the main model of instantaneous release diffusion calculation is formed by the conservation equation set and the auxiliary equation,
wherein:
rho is the density of the mixed tobacco mass (kg/m) 3 )；
u is wind speed (m/s);
b, h are the width and height (m) of the tobacco mass respectively;
Figure BDA0001629775900000181
for mixing UF in the tobacco mass 6 Mass concentration at which no chemical reaction occurs;
Figure BDA0001629775900000182
to release UF 6 Density of tobacco mass (kg/m) 3 )；
Figure BDA0001629775900000183
Is UF 6 The vertical ejection speed (kg/s) of the tobacco mass;
Figure BDA0001629775900000184
is the width (m) of the source;
ρ a is the density of ambient air (kg/m) 3 )；
v e ,w e Horizontal and vertical air entrapment rates (m/s), respectively;
Figure BDA0001629775900000185
respectively the specific heat capacity of the mixed smoke, the specific heat capacity of air and UF 6 The specific heat capacity of the gas;
Δ H is the heat of chemical reaction (J/kmol);
a g ,v g the gravity wave velocities (m/s) of the horizontal downwind direction and the transverse wind direction of the tobacco mass respectively;
g is the acceleration of gravity (9.8 m/s) 2 )；
f u ,f vg ,f w The friction force in downwind direction, transverse wind direction and vertical direction are respectively;
w c is the vertical velocity (m/s) of the mass;
B x ,B y the widths (m) of the mixed tobacco mass in the x direction and the y direction are respectively;
v ex ,v ey air mixing in x and y directions respectivelyA nip roll ratio (m/s);
b,b x ,b y respectively the width parameters of the mixed tobacco mass;
z c is a height parameter of the tobacco mass;
alpha and gamma are respectively parameters for calculating the molecular weight and density of the mixed smoke mass.
2. Four submodels for diffusion calculation
Four submodels are established to provide calculation parameters for the main model, and the calculation formulas of the four submodels are as follows:
(1) wind profile model
du a /dz＝(u a* /kz)·Φ m (z/L)·g(z/H)
Φ m (z/L)＝1+5·L -1 ·z/(1+z/z L (s)
z L (s)＝1+0.8·(s-4)
g(z/H)＝1-z/130·2 (7-s)
Wherein:
u a ambient wind speed (m/s);
u a* ambient friction speed (m/s);
k is von Karman constant;
z is the height (m);
Φ m is a Moore function;
l is the Moore length (m);
h is the mixed layer height (m);
z L (s) a stability parameter;
s is the degree of stability (1-6).
(2) Air entrainment rate model
Figure BDA0001629775900000191
g(h/H)＝1-h/H
Φ h (h/L)＝1+5·h/L,(L≥0)
Φ h (h/L)＝1/(1-16·h/L) 1/2 ,(L＜0)
Figure BDA0001629775900000192
Figure BDA0001629775900000193
Wherein:
w e is the vertical curl ratio (m/s);
a and k are constants respectively;
g (H/H) is a function of the height of the mixed layer;
h is height (m);
h is the mixed layer height (m);
Φ h (h/L) is a Moore height function;
v ey air entrapment rate in horizontal y-direction (m/s);
v ex is the air entrainment rate (m/s) in the horizontal x direction;
v a is a horizontal velocity term;
v j ,v s is the vertical velocity term.
(3) Chemical thermodynamic model
Figure BDA0001629775900000201
Figure BDA0001629775900000202
Figure BDA0001629775900000203
Figure BDA0001629775900000204
ΔH air ＝0.24037·ΔT c
Figure BDA0001629775900000205
Wherein:
ΔH plume enthalpy of the mixed smoke mass (kJ/mol);
Figure BDA0001629775900000206
is UF 6 Enthalpy of component (kJ/mol);
Figure BDA0001629775900000207
is UO 2 F 2 Enthalpy of component (kJ/mol);
Figure BDA0001629775900000208
is HF-H 2 Enthalpy (kJ/mol) of O system components;
ΔH air is the enthalpy of the air component (kJ/mol);
H rxn heat evolved for chemical reactions (kJ/mol);
T r ,T f ,T c respectively at temperature ° R, ° F, ° c;
z P,T is UF 6 A gas compression coefficient;
Figure BDA0001629775900000209
respectively the share of different components of HF;
Figure BDA00016297759000002010
is UF 6 Mass (kg);
Figure BDA00016297759000002011
is UF 6 Molecular weight (g/mol).
(4) Tobacco cluster lifting model
For initial high density UF 6 The discharge, lift calculation is as follows:
Figure BDA0001629775900000211
R v ＝w s /u a
S g ＝ρ s /ρ a
F r ＝w s /[g·D s ·(ρ s -ρ a )/ρ a ] 1/2
D s ＝(4/π 1/2 )·B s
wherein:
h pr is the elevation height (m) of the mixed mass of tobacco;
R v is the wind shear ratio;
S g is the density ratio of the tobacco mass;
F r is a function of gravity;
w s is UF 6 Release speed (m/s);
u a ambient wind speed (m/s);
ρ s ,ρ a are respectively UF 6 Gas density and ambient air density (kg/m) 3 )；
g is the acceleration of gravity (9.8 m/s) 2 )；
D s ,B s Respectively, the width parameter of the source and the width (m) of the source.
Calculating by the main model and the four sub-models, and outputting UF 6 The diffusion distribution of the components in the environment after an accident leak results in a concentration of UF6, UO2F2, HF at different distances downwind.
(III) UF 6 Accident outcome health effect calculation
As heavy metal elements, uranium and compounds thereof are chemical toxic substances; uranium is simultaneously used as alpha radionuclide, and internal irradiation damage can be generated by ingestion and inhalation; and HF uptake can lead to chemical corrosion and burns.
In the calculation of the health effect, the total integrated concentration of uranium, the amount of inhaled uranium, the effective dose to be integrated (CEDE) and the hourly equivalent concentration of HF in the lung are calculated according to the following calculation formulas:
Figure BDA0001629775900000212
Figure BDA0001629775900000213
H E,50 ＝m u ·D u-235 ·A u ·DCF E,50
c 1HF ＝c HF (t)(t/3600) 1/2
wherein:
Figure BDA0001629775900000221
respectively, the integrated concentration of total uranium (mg-s/m) 3 )、UF 6 Concentration (mg/m) 3 )、 UO 2 F 2 Concentration of (mg/m) 3 )；
m u (x) Is the inhaled quantity of uranium (mg);
φ inh is the respiration rate (m) 3 /s)；
H E,50 Effective dose to be accumulated (rem);
D u-235 is the abundance of uranium;
A u specific activity of uranium (μ Ci/g);
DCF E,50 is the effective dose coefficient to be integrated (rem/. mu.Ci);
c 1HF at 1 hour equivalent concentration in the lung (mg/m) 3 )；
t is the irradiation duration(s).
The present invention consists of UF 6 A source term calculation model and a diffusion calculation model, wherein UF is obtained by running the complete calculation model under the condition of known actual accident working condition 6 And calculating the result of the accident consequence. When the parameters of the fault source items are known or the actual working conditions are unknown, the known source item parameters are required to be input or the source item parameters are required to be set to operate independentlyDiffusion calculation model UF 6 And calculating the accident consequence.
Using the exemplary inventive Nuclear Fuel cycle facility UF described above 6 Accident leakage consequence evaluation calculation method calculates three UF performed in France 1986-1989 6 The diffusion experiment was followed, and the prepared input parameter conditions are shown in table 1 below.
TABLE 1 French Tertiary UF 6 Input parameter condition of tracing diffusion field experiment
Figure BDA0001629775900000222
Figure BDA0001629775900000231
The total uranium concentrations at different downwind distances are calculated according to the input parameter conditions in table 1, and the calculation of the health effect is based on the total uranium concentrations, and the actual field experiment data only include the total uranium concentrations, so the experimental value of the total uranium concentrations is compared with the model calculation result of the invention, and the result is shown in table 2 below (P/O is model calculation data/experimental data). Meanwhile, for comparison with other models, the results of calculation of three experiments by HGSYSTEM/UF6 and RASCAL models are shown in the following Table 3. As can be seen from the results in Table 2, the ratio of the calculated results to the experimental data of the model of the present invention is at most 3.21, and the ratio of the model data to the experimental data after 40 m is substantially 1-2.5 times. As can be seen from the results in Table 3, the maximum value of the ratio of the calculation results of the HGSYSTEM/UF6 model to the experimental data is 6.76, and the ratios of the rest data are 1-2.7 times (indicating that the calculation results of the model are all larger); the maximum value of the ratio of the calculation result of the RASCAL model to the experimental data is 1.49, and the ratio of the rest data is below 1 time (which indicates that the calculation result of the model is basically smaller). FIG. 5 is a comparison of P/O results of three models, and it can be seen that the model calculation results of the present invention are substantially between the deviations of the two known model calculation results, and are closer to the actual measurement data of the experiment, except for the two points of the first experiment.
TABLE 2 comparison of the calculated and measured values of the total uranium concentration at different distances in the downwind direction for the model of the invention
Figure BDA0001629775900000232
Figure BDA0001629775900000241
TABLE 3 HGSYSTEM/UF 6 Comparing the calculated value and the measured value of the total uranium concentration of the RASCAL model at different distances in downwind direction
Figure BDA0001629775900000242
In summary, UF of the present invention is illustrated by comparison with experimental data and other models 6 The calculation result goodness of fit of the accident leakage consequence evaluation calculation model is good, and the calculation result of the model is accurate and reliable.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations. The foregoing examples or embodiments are merely illustrative of the present invention, which may be embodied in other specific forms or in other specific forms without departing from the spirit or essential characteristics thereof. The described embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. The scope of the invention should be indicated by the appended claims, and any changes that are equivalent to the intent and scope of the claims should be construed to be included therein.

Claims (7)

1. Nuclear fuel circulation facility UF 6 The accident leakage consequence evaluation and calculation method is characterized by sequentially comprising the following steps of:
(1) determining source item parameters: calculating source item parameters according to actual working conditions, or knowing or assuming the source item parameters;
(2) performing diffusion calculation in an atmospheric environment under different accident situations according to the source item parameters determined in the step (1);
(3)UF 6 the calculation of the health effect of the accident consequence,
wherein:
in the step (2), in order to perform the diffusion calculation, the parameters which need to be input are source parameters including release rate, released smoke mass density and/or released smoke mass temperature and environmental meteorological conditions including wind speed, temperature, humidity, stability and/or surface roughness,
in the step (2), a main model and four sub models are established to perform the diffusion calculation, wherein the calculation equation set of the main model is as follows:
(1) for UF 6 A sustained release scenario, set up as follows a system of principal equations that considers only the downwind distance variable x,
Figure FDA0003709500230000011
Figure FDA0003709500230000012
Figure FDA0003709500230000013
d(ρuBhu)/dx+0.5a g gd[(ρ-ρ a )Bh 2 ]/dx＝ρ a (v e h+w e B)u a +f u
d(ρuBhv g )/dx＝g(ρ-ρ a )h 2 +f vg
d(ρuBhw c )/dx＝-g(ρ-ρ a )Bh+f w
and the following auxiliary equations providing the required calculation parameters for the main equation set calculation,
u(dB/dx)＝(ρ a /ρ)v e +v g
u(db/dx)＝v g ·b/B
u(dz c /dx)＝w c
ρ＝ρ a T a /[αT+γT a ]
solving the main equation set;
(2) for UF 6 The instantaneous mass release scenario, the following set of principal equations is established considering only the time variable t,
Figure FDA0003709500230000021
Figure FDA0003709500230000022
Figure FDA0003709500230000023
(ρB x hu)dB y /dt＝ρ a [(v ex B y +v ey B x )h+w e B x B y ]u a +B x f u
(ρB x hu g )dB y /dt＝g(ρ-ρ a )h 2 B x +B x f vg
(ρB x hv g )dB y /dt＝g(ρ-ρ a )h 2 B y +B x f vg
(ρB x hw c )dB y /dt＝-g(ρ-ρ a )hB x B y +B x f w
and the following auxiliary equations providing the required calculation parameters for the main equation set calculation,
dB y /dt＝(ρ a /ρ)v ey +v g
db y /dt＝v g b y /B y
dB x /dt＝(ρ a /ρ)v ex +u g
db x /dt＝u g b x /β x
u(dz c /dt)＝w c
ρ＝ρ a T a /[αT+γT a ]
solving the main equation set;
in each of the above equations:
rho is the density of the mixed tobacco mass;
u is the wind speed;
b, h are the width and height of the tobacco mass respectively;
Figure FDA0003709500230000024
for mixing UF in the tobacco mass 6 Mass concentration at which no chemical reaction occurs;
Figure FDA0003709500230000025
to release UF 6 The density of the tobacco mass;
Figure FDA0003709500230000026
is UF 6 The vertical ejection speed of the tobacco mass;
Figure FDA0003709500230000027
is the width of the source;
ρ a is the ambient air density;
T，T a and
Figure FDA0003709500230000028
respectively mixed tobacco mass temperature, ambient atmospheric temperature and UF 6 The temperature of (a);
v e ,w e horizontal and vertical air entrapment rates, respectively;
Figure FDA0003709500230000029
respectively the specific heat capacity of the mixed smoke mass, the specific heat capacity of air and UF 6 The specific heat capacity of the gas;
c p the specific heat capacity of the mixed smoke mass;
u a is the ambient wind speed;
u g is the horizontal gravity wave velocity;
Δ H is the heat of chemical reaction;
a g ,v g the gravity wave velocities of the horizontal downwind direction and the transverse wind direction of the tobacco mass respectively;
g is the acceleration of gravity;
f u ,f vg ,f w the friction force in downwind direction, transverse wind direction and vertical direction are respectively;
w c is the vertical velocity of the tobacco mass;
B x ,B y the widths of the mixed tobacco mass in the x direction and the y direction are respectively;
v ex ,v ey air mixing entrapment rates in the x and y directions respectively;
b,b x ,b y respectively the width parameters of the mixed tobacco mass;
z c is a height parameter of the tobacco mass;
alpha and gamma are respectively parameters for calculating the molecular weight and density of the mixed smoke group;
the calculation formulas of the four submodels are as follows:
(1) wind profile model
du a /dz＝(u a* /kz)Φ m (z/L)g(z/H)
Φ m (z/L)＝1+5L -1 z/(1+z/z L (s))
z L(s) ＝1+0.8(s-4)
g(z/H)＝1-z/130·2 (7-s)
Wherein:
u a is the ambient wind speed;
u a* ambient friction speed;
k is von Karman constant;
z is the height;
Φ m is a Moore function;
l is the Moore length;
h is the height of the mixed layer;
z L (s) a stability parameter;
s is the stability;
(2) air entrainment rate model
Figure FDA0003709500230000031
g(h/H)＝1-h/H
Φ h (h/L)＝1+5h/L,L≥0
Figure FDA0003709500230000041
Figure FDA0003709500230000042
Figure FDA0003709500230000043
Wherein:
w e is the vertical nip rate;
a and k are constants respectively;
u * the ambient friction speed;
g (H/H) is a function of the height of the mixed layer;
h is the height;
h is the height of the mixed layer;
Φ h (h/L) is a Moore height function;
v ey air entrainment rate in horizontal y direction;
v ex air entrapment rate in horizontal x direction;
v a is a horizontal velocity term;
v j ,v s is a vertical velocity term;
(3) chemical thermodynamic model
Figure FDA0003709500230000044
Figure FDA0003709500230000045
Figure FDA0003709500230000046
Figure FDA0003709500230000047
ΔH air ＝0.24037ΔT c
Figure FDA0003709500230000048
Wherein:
ΔH plume is the enthalpy of the mixed smoke mass;
Figure FDA0003709500230000049
is UF 6 The enthalpy of the component;
Figure FDA00037095002300000410
is UO 2 F 2 The enthalpy of the component;
Figure FDA00037095002300000411
is HF-H 2 Enthalpy of O system component;
ΔH air is the enthalpy of the air component;
H rxn heat given off for chemical reactions;
ΔT r ,ΔT f and Δ T c The temperature changes are respectively in the unit of degree R, degree F and degree C;
z P,T is UF 6 A gas compression factor;
Figure FDA0003709500230000051
Figure FDA0003709500230000052
and
Figure FDA0003709500230000053
respectively the share of different components of HF;
Figure FDA0003709500230000054
is UF 6 The mass of (c);
Figure FDA0003709500230000055
is UF 6 The molecular weight of (a);
(4) tobacco cluster lifting model
For initial high density UF 6 Discharging the waste water, and discharging the waste water,
Figure FDA0003709500230000056
R v ＝w s /u a
S g ＝ρ s /ρ a
Figure FDA0003709500230000057
Figure FDA0003709500230000058
wherein:
h pr the lifting height of the mixed tobacco mass;
R v is the wind shear ratio;
S g is the density ratio of the tobacco mass;
F r is a function of gravity;
w s is UF 6 The release speed;
u a is the ambient wind speed;
ρ s ,ρ a are respectively UF 6 Gas density and ambient air density;
g is the acceleration of gravity;
D s ,B s respectively the width parameter of the source and the width of the source;
the calculation output result of the main model and the four submodels is the downwind UF 6 、UO 2 F 2 The concentration of HF at different distances,
in the step (3), the parameters for calculating the health effect comprise the total integrated concentration of uranium, the inhaled uranium amount, the effective dose to be integrated and the equivalent concentration of HF hour in lung, and the calculation formula is as follows:
Figure FDA0003709500230000059
Figure FDA00037095002300000510
H E,50 ＝m u D u-235 A u DCF E,50
c 1HF ＝c HF (t)(t/3600) 1/2
wherein:
Figure FDA0003709500230000061
and
Figure FDA0003709500230000062
total integrated concentration of uranium, UF 6 Concentration and UO 2 F 2 The concentration of (d);
m u (x) Is the uptake of uranium;
H E,50 is an effective dose to be accumulated;
D u-235 is the abundance of uranium;
A u is the specific activity of uranium;
DCF E,50 is the effective dose coefficient to be accumulated;
c 1HF 1 hour equivalent concentration in lung;
t is the duration of irradiation;
Figure FDA0003709500230000063
is the respiratory rate of an adult.
2. The evaluation calculation method according to claim 1, characterized in that: in step (1), the determined source parameters include UF 6 Release rate, plume two-phase fraction, plume density, and/or plume temperature.
3. The evaluation calculation method according to claim 2, characterized in that: in the step (1), the source item parameters are calculated and determined according to three conditions, wherein the three conditions are UF 6 Sustained release of liquid, UF 6 Sustained release of gas and copious UF 6 The liquid is released instantaneously.
4. The evaluation calculation method according to claim 3, wherein: in the step (1), in order to calculate and determine the source parameter, the input actual working condition parameters comprise container temperature, container pressure, container loading capacity and container damage size.
5. The evaluation calculation method according to claim 4, wherein in step (1), in UF 6 Under the condition of liquid sustained release, the calculation formulas of the source term parameters are respectively as follows:
Figure FDA0003709500230000064
Figure FDA0003709500230000065
Figure FDA0003709500230000071
wherein:
q is liquid UF 6 The release rate;
c is a constant;
a is the leakage area;
ρ l is UF 6 The density of the liquid;
P r ,P a respectively the pressure in the container and the ambient pressure;
g is the acceleration of gravity;
h is a pressure head;
f is UF in the tobacco mass 6 Fraction of gaseous form;
m l is an initial UF 6 The total mass of the liquid;
λ f ，λ s are respectively UF 6 Heat of solution and UF for solid-liquid conversion 6 Sublimation heat of solid-gas conversion;
c pl ，c ps ，c pv are respectively UF 6 Constant pressure heat capacity of liquid, solid and gas phases;
T r ,T s ,T t are respectively UF 6 Vessel temperature, UF 6 Sublimation temperature, UF 6 The triple point temperature;
rho is the density of the gas-solid mixed smoke mass after the initial release flash evaporation;
w is UF 6 The total mass;
Figure FDA0003709500230000072
respectively UF at sublimation point 6 Gas and solid density of (a).
6. The evaluation calculation method according to claim 4, wherein in step (1), in UF 6 In the case of sustained release of gas, the determination of each of the source parameters is as follows:
(1) calculating the saturated vapor pressure when the gas phase and the condensed phase in the container are balanced when an accident occurs, namely the pressure of the storage tank,
Figure FDA0003709500230000073
wherein:
T r is UF 6 The temperature at which the two phases in the vessel equilibrate;
P r is the pressure in the container;
(2) calculating the gas flow pressure according to the formula, if the gas flow pressure is greater than the ambient pressure, the leakage is choked flow, otherwise, subcritical flow,
Figure FDA0003709500230000081
wherein:
for UF 6 ，γ＝1.07；
P is the gas flow pressure;
(3) for the choked flow, the calculation formula of each source term parameter is respectively as follows,
Q＝cAP r [(γM/RT r )(2/(γ+1)) (γ+1)/(γ-1) ] 1/2
T＝T r [1-(0.85)(γ-1)/(γ+1)]
Figure FDA0003709500230000082
wherein:
q is UF 6 The release rate;
c is a constant;
a is the leakage area;
P r the pressure of the storage tank;
for UF 6 ，γ＝1.07；
M is UF 6 A molecular weight;
r is an ideal gas constant;
T r is UF 6 The temperature of the storage tank;
t is the temperature of the released gas plume;
ρ * is a leaked UF 6 (ii) the mass density of the tobacco;
P a is ambient atmospheric pressure;
(4) for subcritical flows, the calculation formula of each source term parameter is as follows, Q ═ cA {2 ρ { v P r γ/(γ-1)[(P a /P r ) 2/γ -(P a /P r ) (γ+1)/γ ]} 1/2
T＝2T r /[1+(1+4ET r ) 1/2 ]
E＝[1/(2c p )][QR/(PMA)] 2
Figure FDA0003709500230000091
Wherein:
q is UF 6 The release rate;
c is a constant;
a is the leakage area;
ρ v is UF 6 The gas density in the storage tank;
P r is UF 6 The gas pressure in the storage tank;
T r is UF 6 The temperature of the gas in the storage tank;
t is the temperature of the leaked tobacco mass;
e is a correction function;
m is UF 6 A molecular weight;
r is an ideal gas constant;
c p constant pressure heat capacity;
ρ * is UF of leaks 6 (ii) the mass density of the tobacco;
p is UF at leakage 6 The pressure of the gas flow;
gamma is the ratio of isobaric to isochoric heat capacities for UF 6 ，γ＝1.07。
7. The evaluation calculation method according to claim 4, wherein in step (1), a large amount of UF 6 In the case of an instantaneous release of liquid, the calculation of the density and the gas fraction of the formed mass after release are respectively as follows:
Figure FDA0003709500230000092
Figure FDA0003709500230000093
wherein:
m l is an initial UF 6 The total mass of the liquid;
λ f ，λ s are respectively UF 6 Heat of solution and UF for solid-liquid conversion 6 Sublimation heat of solid-gas conversion;
c pl ，c ps ，c pv are respectively UF 6 Constant pressure heat capacity of liquid, solid and gas phases;
T r ,T s ,T t are respectively UF 6 The temperature of the container, the sublimation temperature and the triple point temperature;
ρ * is UF 6 (ii) the mass density of the tobacco;
ρ v and ρ s Are respectively UF 6 Density in the gaseous and solid state.
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