A design method for timely emission of waste gas from nuclear facilities

Abstract

The present invention relates to a design method for timely emission of waste gas from a nuclear facility, comprising: (1) selecting conventional meteorological observation data of a meteorological tower at a nuclear facility site and three-dimensional turbulence data of a certain period of time as a data basis; (2) establishing a similarity relationship between conventional meteorological observation data of a meteorological tower at a nuclear facility site and three-dimensional turbulence data, and calculating the roughness of the site; (3) calculating the hourly turbulent pulsation velocity of the site, and at the same time calculating the Richardson number of the corresponding period of time and the corresponding mixing length, and then calculating the corresponding Lagrangian time scale; (4) substituting the hourly data in step (3) into the Taylor formula to calculate the hourly diffusion parameter; (5) calculating the maximum concentration caused by the diffusion parameter obtained and the wind speed at the current moment, and emitting waste gas when the maximum concentration is lower than the set limit. The present invention uses conventional meteorological observation data of a meteorological tower for decision-making on the timing of nuclear facility emission, and expands the application value of the data of the meteorological tower of a nuclear facility.

Description

Technical Field

[0001] The invention relates to a technology for estimating atmospheric diffusion parameters of a nuclear environment, and in particular to a design method for timely emission of waste gas from a nuclear facility. Background Art

[0002] In the environmental assessment, facility design and daily production of nuclear facilities, it is necessary to consider the atmospheric dilution capacity of the area where the site is located. The diffusion parameter is a comprehensive indicator for evaluating the diffusion dilution capacity of the site, and the diffusion parameter has important guiding significance for the timing of nuclear facility emissions.

[0003] In actual work, the following methods are generally used to estimate diffusion parameters: 1) Atmospheric diffusion tracer experiment, atmospheric tracers are released at the plant site, and the atmospheric diffusion parameters under the dominant wind direction are estimated based on the sampling results. This method is close to reality, but the experimental cycle is long and the cost is high. It can only estimate the atmospheric diffusion parameters based on the diffusion situation in some time periods, and cannot reflect the diffusion parameter characteristics under different meteorological conditions of the plant site throughout the year. 2) Using three-dimensional turbulence observation equipment, the diffusion parameters are estimated by observing the three-dimensional turbulence pulsation. This method can observe a complete time series, so the complete diffusion parameters under various stability levels can be obtained. This method is easier to implement than the atmospheric diffusion tracer experiment, but the three-dimensional turbulence pulsation observation equipment is expensive and easy to damage. In practice, it is only used for observations of dozens of days or months and cannot be deployed for a long time. The atmospheric boundary layer turbulence pulsation can also be calculated using conventional iron tower meteorological observation data through turbulence parameterization methods. Considering that nuclear facilities are generally equipped with conventional meteorological observation towers, it is possible to consider using meteorological tower observation data to estimate real-time diffusion parameters, thereby guiding the real-time emission system of nuclear facilities. Summary of the invention

[0004] The purpose of the present invention is to provide a design method for timely emission of waste gas from nuclear facilities, which uses conventional meteorological data of nuclear facilities and some three-dimensional turbulence observation data, establishes a similarity relationship between conventional meteorological observation data of meteorological towers and three-dimensional turbulence observation data through similarity theory, estimates real-time diffusion parameters of the area where the nuclear facility is located, and then calculates the real-time maximum landing concentration in the estimated emission, and determines whether the nuclear facility should emit after comparing it with a predetermined limit.

[0005] The technical solution of the present invention is as follows: A design method for timely emission of waste gas from nuclear facilities, comprising the following steps:

[0006] (1) Select conventional meteorological observation data from the meteorological tower at the nuclear facility site and three-dimensional turbulence data for certain periods of time as the data basis;

[0007] (2) Establish the similarity relationship between conventional meteorological observation data and three-dimensional turbulence data of the meteorological tower at the nuclear facility site, and calculate the roughness of the site;

[0008] (3) Using the established similarity relationship, calculate the hourly turbulent pulsation velocity at the plant site, and simultaneously calculate the Richardson number and the corresponding mixing length of the corresponding time period, and then calculate the corresponding Lagrangian time scale;

[0009] (4) Substituting the hourly data in step (3) into Taylor's formula to calculate the hourly diffusion parameters;

[0010] (5) The maximum concentration is calculated based on the obtained diffusion parameters and the current wind speed. When the maximum concentration is lower than the set limit, exhaust gas is discharged.

[0011] Furthermore, in the design method for timely emission of waste gas from nuclear facilities as described above, the conventional meteorological observation data of the meteorological tower described in step (1) includes wind speed, wind direction and temperature of each layer of the meteorological tower, and the three-dimensional turbulent pulsation data includes three-dimensional wind speed and temperature pulsation.

[0012] Further, in the design method for timely emission of waste gas from nuclear facilities as described above, the method for establishing the similarity relationship between conventional meteorological observation data of the meteorological tower at the nuclear facility site and the three-dimensional turbulence data in step (2) is as follows:

[0013] According to the similarity theory of atmospheric boundary layer turbulence, the turbulent pulsation velocity satisfies the following similarity relationship:

[0014]

[0015] Among them, σ u,v,w Represents σ u or v or w , are the longitudinal, lateral and vertical turbulent fluctuation velocities, U * Indicates the characteristic speed. Different parameters should be used according to different situations, such as ground friction speed, F u,v,w (z / L,h / L) is a dimensionless function corresponding to the longitudinal, lateral and vertical directions, z is the height, h is the characteristic scale of the atmospheric boundary layer, and L is the Monin-Obukhov length:

[0016]

[0017] Among them, U * is the characteristic speed, k is the Kelman constant, which is taken as 0.38, θ is the potential temperature, w is the vertical speed, θ' is the temperature fluctuation, w' is the vertical speed fluctuation,

[0018] Considering only the similarity relationship function of the ground layer near the nuclear facility, it is as follows:

[0019]

[0020] Here *Taking the ground friction velocity, for the neutral stratification:

[0021]

[0022] The strength of turbulent diffusion can be measured by the turbulence in three directions. u ,I v ,I w To measure, they are:

[0023]

[0024] Where U is the average wind speed. If the wind speed profile also obeys the Monin-Obukhov similarity, then the turbulence also obeys the similarity.

[0025] Through some turbulence observation data and conventional meteorological observation data, the functional form of the similarity relationship and the values ​​of A, B, and C under neutral conditions are determined.

[0026] Furthermore, in the design method for timely emission of waste gas from nuclear facilities as described above, in step (2), it is assumed that the air layer below a height of 100 meters complies with the law of the near-ground layer: The wind profile data of neutral stability throughout the year are selected, and the least square method is used to estimate the ground roughness. u2 and u1 are the wind speeds corresponding to heights z2 and z1 respectively, and z0 is the ground roughness.

[0027] Further, in the design method for timely emission of waste gas from nuclear facilities as described above, the method for calculating the Richardson number in step (3) is as follows:

[0028] Represent the wind speed gradient in the vertical direction, It represents the potential temperature gradient, which can be calculated from the conventional meteorological observation data of the meteorological tower. The stability function S h , S m It can be expressed as the flux Richardson number R f Function:

[0029]

[0030]

[0031] Among them, the flux Chasen number R f By the gradient Richardson number R i Find:

[0032]

[0033] Among them, C h , C m , R f1 , R f2 is a constant, Rfc represents the critical flux Richardson number, R i When ≥0.191, R ifc Take the constant 0.2.

[0034] Furthermore, in the design method for timely emission of waste gas from nuclear facilities as described above, the method for calculating the Lagrangian time scale in step (3) is as follows:

[0035] l represents the size of the turbulent eddy scale that affects the diffusion of pollutants. Its calculation result is the variable of height z from the ground and stability:

[0036]

[0037] Where k = 0.38, S m is the stability function,

[0038] The Grangian time scale can be expressed as, c t is a constant:

[0039]

[0040] T L u 、T L v 、T L w are the Lagrangian time scales in the horizontal u, v and w directions respectively, and u', v' and w' represent the turbulent pulsation velocities in the three directions respectively.

[0041] Further, in the design method for timely emission of waste gas from nuclear facilities as described above, the method for calculating the diffusion parameter in step (4) is as follows:

[0042]

[0043] In the formula, σ i is the horizontal or vertical diffusion parameter, σ i is the horizontal or vertical turbulent pulsation velocity, t L is the Lagrangian time scale and T is the diffusion time.

[0044] Further, in the design method for timely emission of waste gas from nuclear facilities as described above, the calculation method of the maximum concentration in step (5) is as follows:

[0045]

[0046] Among them, q m is the maximum concentration, Q is the release rate, u is the wind speed, H is the release height, e is the natural constant, σ z , σ y are the vertical and horizontal diffusion parameters, respectively.

[0047] Furthermore, in the design method for timely emission of waste gas from nuclear facilities as described above, the limit value in step (5) is set by the nuclear facility based on the characteristic nuclides emitted by the nuclear facility.

[0048] The beneficial effects of the present invention are as follows: The design method for timely emission of waste gas from nuclear facilities provided by the present invention uses the meteorological observation tower built by the nuclear facility and dozens of days of turbulence observation to obtain basic data, calculates the turbulence characteristics of the nuclear facility using the similarity relationship established between the conventional observation data of the nuclear facility and the turbulence observation data, and uses conventional observation data to infer the diffusion parameters, making it feasible to obtain the diffusion parameters in real time, meeting the needs of nuclear facilities for emission timing selection. The present invention uses the conventional meteorological observation data of the meteorological tower for nuclear facility emission timing decision-making, expanding the application value of the nuclear facility meteorological tower data; compared with the method of estimating diffusion parameters by atmospheric diffusion tracer experiments and turbulence observation, the present invention can obtain a sequence of real-time diffusion parameters throughout the year, providing a decision basis for the emission timing of nuclear facilities, and optimizing the degree of impact of nuclear facility emissions on the surrounding environment. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0050] The present invention uses conventional meteorological data of nuclear facilities and some three-dimensional turbulence observation data, establishes a similarity relationship between conventional meteorological observation data of iron towers and three-dimensional turbulence observation data through similarity theory, and estimates the real-time diffusion parameters of the area where the nuclear facilities are located. Specifically, it includes the following steps:

[0051] (1) Conventional meteorological observation data from the meteorological tower at the plant site and three-dimensional turbulence data from certain periods of time were selected as the data basis, including wind speed, wind direction, temperature and three-dimensional wind speed and temperature pulsation data of each layer of the meteorological tower.

[0052] (2) Establish a similarity relationship between the conventional observation data and turbulence data of the meteorological tower at the plant site, and calculate the roughness of the plant site.

[0053] Assuming that the air layer below 100 meters in height follows the law of the near-surface layer (as shown in the following formula), the wind profile data of neutral stability throughout the year are selected and the least squares method is used to estimate the surface roughness:

[0054]

[0055] Among them, u2 and u1 are the wind speeds corresponding to heights z2 and z1 respectively, and z0 is the ground roughness.

[0056] Through some turbulence observation data and the conventional meteorological observation data of the meteorological tower during the same period, the similarity relationship between conventional observation data and turbulent pulsation quantity is established. According to the similarity theory of atmospheric boundary layer turbulence, the standard deviation of turbulent velocity fluctuations satisfies the following similarity relationship:

[0057]

[0058] Here σ u,v,w Represents σ u or v or w , are the longitudinal, lateral and vertical turbulent fluctuation velocities, U * It is an appropriate characteristic speed. Different parameters should be taken according to different situations, such as ground friction speed. u,v,w (z / L,h / L) is a dimensionless function corresponding to the three directions, Z is the height, h is the characteristic scale of the atmospheric boundary layer, and L is the Monin-Obukhov length:

[0059]

[0060] Among them, U * is the dimensionless velocity, k is the Kelman constant, which is taken as 0.38, θ is the potential temperature, w is the vertical velocity, θ' is the temperature fluctuation, w' is the vertical velocity fluctuation,

[0061] Only consider the similarity relationship function of the ground layer near the nuclear facility:

[0062]

[0063] Here * Taking the ground friction velocity, for the neutral stratification:

[0064]

[0065] The strength of turbulent diffusion can be measured by the turbulence in three directions, which are:

[0066]

[0067] Here U is the average wind speed. If the wind speed profile also obeys the Monin-Obukhov similarity, then the turbulence also obeys the similarity.

[0068] Through some turbulence observation data and conventional observation data, the functional form of the similarity relationship and the values ​​of A, B, and C under neutral conditions are determined.

[0069] (3) Calculate the real-time turbulent pulsation quantity (turbulent pulsation velocity) σ at the plant site based on the established similarity relationship u or v or w, and calculate the Richardson number for that hour and the corresponding mixing length l, and then calculate the corresponding Lagrangian time scale.

[0070] They represent the vertical wind speed gradient and potential temperature gradient, which can be calculated from the conventional meteorological observation data of the meteorological tower. h , S m It can be expressed as the flux Richardson number R f Function:

[0071]

[0072]

[0073] Among them, the flux Chasen number R f By the gradient Richardson number R i Find:

[0074]

[0075] Among them, C h , C m , R f1 , R f2 is a constant, R fc represents the critical flux Richardson number, R i When ≥0.191, R ifc Take the constant 0.2.

[0076] l represents the size of the turbulent eddy that affects the diffusion of pollutants. Its calculation result is the variable of height from the ground and stability:

[0077]

[0078] Where k = 0.38, S m is the stability function,

[0079] The Grangian time scale can be expressed as, c t is a constant:

[0080]

[0081] T L u 、T L v 、T L w are the Lagrangian time scales in the horizontal u, v and w directions respectively, and u', v' and w' represent the velocity pulsation speeds in the three directions respectively.

[0082] The above relationship can be used to calculate the value of the turbulent pulsation velocity and the Lagrangian time scale.

[0083] (4) Substitute the hourly data in step (3) into the Taylor formula to calculate the hourly diffusion parameters.

[0084] Substitute the turbulent velocity pulsation velocity and Lagrangian time scale calculated from the hourly data into the Taylor formula to solve the diffusion parameter at the corresponding time. The Taylor formula is as follows:

[0085]

[0086] In the formula, σ i is the horizontal or vertical diffusion parameter, σ i is the horizontal or vertical turbulent pulsation velocity, t L is the Lagrangian time scale and T is the diffusion time.

[0087] (5) Emissions are made when the maximum concentration caused by the estimated diffusion parameters and the current wind speed is below the set limit, which is set by the nuclear facility based on the characteristic nuclides it emits.

[0088] The current maximum ground concentration is calculated from the diffusion parameters and wind speed:

[0089]

[0090] Among them, q m is the maximum concentration, Q is the release rate, u is the wind speed, H is the release height, e is the natural constant, σ z , σ y are the vertical and horizontal diffusion parameters, respectively.

[0091] Since the characteristic nuclides of different nuclear facilities are different, the limit value q is determined according to the characteristic nuclides of nuclear facilities. level , when q m <q level Discharge at the time.

[0092] It will be apparent to those skilled in the art that the structure of the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that fall within the meaning and scope of the equivalent elements of the claims be included in the invention. Markings in the claims should not be considered as limiting the claims to which they relate.

[0093] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A design method for timely emission of waste gas from nuclear facilities, characterized in that: The steps include: (1) Select conventional meteorological observation data from the meteorological tower at the nuclear facility site and three-dimensional turbulence data for certain periods of time as the data basis; (2) Establish a similarity relationship between conventional meteorological observation data and three-dimensional turbulence data of the meteorological tower at the nuclear facility site, and calculate the site roughness; the method for establishing a similarity relationship between conventional meteorological observation data and three-dimensional turbulence data of the meteorological tower at the nuclear facility site is as follows: According to the similarity theory of atmospheric boundary layer turbulence, the turbulent pulsation velocity satisfies the following similarity relationship: Among them, σ u,v,w Represents σ u or v or w , are the longitudinal, lateral and vertical turbulent fluctuation velocities, U * represents the characteristic velocity, F u,v,w (z / L,h / L) is a dimensionless function corresponding to the longitudinal, lateral and vertical directions, z is the height, h is the characteristic scale of the atmospheric boundary layer, and L is the Monin-Obukhov length: Among them, U * is the characteristic speed, k is the Kelman constant, θ is the potential temperature, θ' is the temperature fluctuation, W' is the vertical fluctuation speed, Considering only the similarity relationship function of the ground layer near the nuclear facility, it is as follows: Here * Taking the ground friction velocity, for the neutral stratification, we have: The strength of turbulent diffusion can be measured by the turbulence in three directions. u ,I v ,I w To measure, they are: Where U is the average wind speed. If the wind speed profile also obeys the Monin-Obukhov similarity, then the turbulence also obeys the similarity. Through some turbulence observation data and conventional meteorological observation data, the functional form of the similarity relationship and the values ​​of A, B, and C under neutral conditions are determined; (3) Using the established similarity relationship, calculate the hourly turbulent pulsation velocity at the plant site, and simultaneously calculate the Richardson number and the corresponding mixing length of the corresponding time period, and then calculate the corresponding Lagrangian time scale; (4) Substituting the hourly data in step (3) into Taylor's formula to calculate the hourly diffusion parameters; (5) The maximum concentration is calculated based on the obtained diffusion parameters and the current wind speed. When the maximum concentration is lower than the set limit, exhaust gas is discharged.

2. The design method for timely discharge of nuclear facility waste gas as claimed in claim 1, characterized in that: The conventional meteorological observation data of the meteorological tower described in step (1) include wind speed, wind direction and temperature of each layer of the meteorological tower, and the three-dimensional turbulent pulsation data include three-dimensional wind speed and temperature pulsation.

3. The design method for timely emission of nuclear facility waste gas as claimed in claim 1, characterized in that: In step (2), it is assumed that the air layer below 100 meters in height follows the law of the near-ground layer: Among them, u2 and u1 are the wind speeds corresponding to heights z2 and z1 respectively, z0 is the ground roughness, and the wind profile data with neutral stability throughout the year are selected, and the least squares method is used to estimate the ground roughness.

4. The design method for timely emission of nuclear facility waste gas as claimed in claim 1, characterized in that: The method for calculating the Richardson number in step (3) is as follows: They represent the wind speed gradient in the vertical direction, It represents the potential temperature gradient, which can be calculated from the conventional meteorological observation data of the meteorological tower. The stability function S h , S m It can be expressed as the flux Richardson number R f Function: Among them, the flux Chasen number R f By the gradient Richardson number R i Find: Among them, C h , C m , R f1 , R f2 is a constant, R i When ≥0.191, R ifc Take the constant 0.

2.

5. The design method for timely emission of nuclear facility waste gas as claimed in claim 1, characterized in that: The method for calculating the Lagrangian time scale in step (3) is as follows: l represents the size of the turbulent eddy that affects the diffusion of pollutants. Its calculation result is the variable of height z from the ground and stability: Where k = 0.38, S m is the stability function, The Grangian time scale can be expressed as, c t is a constant: T L u , T L v , T L w are the Lagrangian time scales in the horizontal u, v and w directions respectively, and u', v' and w' represent the turbulent pulsation velocities in the three directions respectively.

6. The design method for timely discharge of nuclear facility waste gas as claimed in claim 1, characterized in that: The method for calculating the diffusion parameter in step (4) is as follows: In the formula, σ i is the horizontal or vertical diffusion parameter, σ i is the horizontal or vertical turbulent pulsation velocity, t L is the Lagrangian time scale and T is the diffusion time.

7. The design method for timely discharge of nuclear facility waste gas as claimed in claim 1, characterized in that: The maximum concentration in step (5) is calculated as follows: Among them, q m is the maximum concentration, Q is the release rate, u is the wind speed, H is the release height, e is the natural constant, σz and σy are the vertical and horizontal diffusion parameters respectively.

8. The design method for timely emission of nuclear facility waste gas as claimed in claim 1, characterized in that: The limit value described in step (5) is set by the nuclear facility based on the characteristic nuclides it emits.

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