CN103413062B - A kind of computational methods of radionuclide diffusion - Google Patents

Abstract

The present invention relates to the computational methods of a kind of radionuclide diffusion, the method use radioactivity cloud cluster diffusion zone divide geographic grid unit and on grid cell superposition two dimension wind field, use the movement of correlation model simulated emission cloud cluster, evolution the coverage of radioactivity cloud cluster and radioactive concentration thereof after finally trying to achieve the scheduled time；The computational methods that this radionuclide utilizing the present invention to provide spreads, it is possible to the radionuclide caused by serious nuclear accident of prediction burst reveals diffusion tendency in an atmosphere, and then determines the range of scatter of radionuclide.

Description

A kind of computational methods of radionuclide diffusion

Technical field

The present invention relates to environmental pollution treatment field, be specifically related to the computational methods of a kind of radionuclide diffusion.

Background technology

Nuclear energy is increasingly favored by people as the energy of a kind of cleaning, safety, utilizes more and more extensive.Nuclear power station The history of development is it has been proved that the safety records of nuclear power station is good.But modern science and technology can not definitely get rid of serious nuclear accident The probability occurred.The nuclear accident caused such as manual operation fault: the serious core of U.S.'s Three Mile Island nuclear reactor generation in 1973 Leak, and more serious Chernobyl Plants in 1986 4 reactor explodes, and causes 30 people to die instantly, 8 tons Many intense radiations thing leaks, and around power station, more than 60,000 square kilometre of soil is directly polluted, and more than 320 ten thousand people are encroached on by radioprotective, For another example natural disaster causes Fukushima, Japan nuclear power station blast in 2011, and substantial amounts of radioprotective is diffused into outside, and people in serious threat Class living environment and healthy and safe.

Nuclear energy is not only and can be used as the energy, it is also possible to be taken as weapon to use in battlefield, as in World War II, the U.S. to 2 atomic bomies have been thrown by Japan, and the radionuclide that nuclear explosion produces is at middle Atmospheric Diffusion, the long-term shadow brought to surrounding enviroment Ring.For serious nuclear accident, what harm was maximum is the diffusion of the radionuclide of nuclear explosion or nuclear leakage generation, in diffusion region In the range of territory, drastically influence the health and safety of the people around.

In the case of there is this uncontrollable nuclear accident, for protecting life and health and the peace of the people around nuclear accident point Entirely, need to take the measure of necessity, the number of casualties is preferably minimized.Before this, determine the pollution range that radionuclide spreads Region, it was predicted that in after a while, the regional extent that radionuclide can be diffused into becomes a difficult problem the most urgently to be resolved hurrily.

At present, in the nuclear accident in correlation technique, model of atmospheric diffusion mainly has three classes, i.e. Lagrange cigarette group model, height This maturity degree and Three-dimensional numerical calculation model.Owing to, in nuclear explosion accident, air is in an unsure state, and Gauss cigarette Plumage model is premised on assuming that air is in steady statue, therefore uses Gaussian plume model to be not appropriate for, and three-dimensional numerical value Computation model amount of calculation is excessive, expends the time longer, is difficult to meet requirement in practice, although Lagrange cigarette rolls into a ball model Radioactive substance spatial and temporal distributions in propagation in atmosphere can be calculated the most really at complex condition, but traditional process Method is to process the cigarette group of release continuously, for uncontrollable serious nuclear accident condition, it is difficult to be suitable for.

Summary of the invention

In view of this, the invention provides the computational methods of a kind of radionuclide diffusion, it is possible to it is serious that prediction happens suddenly Radionuclide caused by nuclear accident reveals diffusion tendency in an atmosphere, and then determines the range of scatter of radionuclide.

The concrete scheme of the present invention is such that the computational methods of a kind of radionuclide diffusion, including:

Step one, determine on map occur radionuclide reveal region, determine the archicenter of radioactivity cloud cluster Coordinate；

Step 2, the region occurring radionuclide to reveal is carried out geographic grid division, combined with hardware computing capability and Display effect determines suitable grid cell size；

Step 3, in each grid cell, carry out the two-dimentional wind field superposition of constant duration according to meteorological data；

Step 4, situation according to radioactive nucleus leakage determine radionuclide diffusion model, and combine archicenter and sit Mark, active nucleus leak time and two dimension wind field calculate each grid cell concentration value；

Step 5, concentration value according to each grid cell judge whether radioactivity cloud cluster divides, if it is not, enter step Six, if so, enter step 7；

Step 6, calculate new archicenter coordinate according to two dimension wind field, and enter step 4；

Step 7, determine the number of radioactivity cloud cluster, and calculate the archicenter coordinate of each radioactivity cloud cluster, according to step Rapid four calculate each radioactivity cloud cluster contribution margin to grid cell concentration；

Step 8, the contribution margin of grid cell concentration is sued for peace by each radioactivity cloud cluster, obtain each grid cell dense Angle value；

Step 9, the step 7 that repeats, eight times preset until time arrival；

Step 10, setting concentration threshold, indicia grid unit concentration is more than the grid of threshold value；

Step 11, the concentration of the grid cell of labelling is mapped to rgb space, draws whole diffusion zone figure, obtain Whole radionuclide diffusion zone figure.

Beneficial effect:

The present invention uses radionuclide diffusion model, geospatial analysis, visualization technique, by obtaining incident point ground Reason data, analyze the feature of its topography and geomorphology, in conjunction with meteorological condition at that time, obtain wind field weather information, analyze the fortune of wind field Dynamic rule, determines diffusion model parameter values, uses diffusion model to calculate the radionuclide concentration of incident point surrounding Value, it was predicted that go out contaminated regional extent within the incident time period.Therefore the present invention is to occurring that uncontrollable nuclear accident is urgent In the case of, have and important instruct decision-making meaning.

Accompanying drawing explanation

Fig. 1 is the flow chart of the computational methods of the radionuclide diffusion of the present invention；

Fig. 2 is the geographic grid cell schematics of the present invention；

Fig. 3 is the leakage spot radioactive cloud cluster centre position view of the present invention；

Fig. 4 is the radioactivity cloud cluster division schematic diagram of the present invention；

Fig. 5 is the radionuclide diffusion zone functional flow diagram of the present invention.

Detailed description of the invention

The present invention provides the computational methods that a kind of radionuclide spreads, as shown in Fig. 1～Fig. 5, including:

Step one, determine on map occur radionuclide reveal region, determine the archicenter of radioactivity cloud cluster Coordinate；

The determination of archicenter coordinate is particularly significant, carries it in Radionuclides Cloud centre coordinate mathematical model just New centre coordinate can be tried to achieve.

Step 2, the region occurring radionuclide to reveal is carried out geographic grid division, combined with hardware computing capability and Display effect determines suitable grid cell size；

The result divided wants to reflect rightly the change procedure of radioactivity cloud cluster, considers the meter of computer hardware simultaneously Calculation ability, makes the smoothness that system is run.

Step 3, in each grid cell, carry out the two-dimentional wind field superposition of constant duration according to meteorological data；Due to Wind field is continually changing, and needs constantly to update wind field data.Here two-dimentional wind field superposition specifically refers to: according to each Two-dimentional wind field on geographical position corresponding to grid is added on grid.

Step 4, leakage situation according to radionuclide determine radionuclide diffusion model, and combine archicenter Coordinate, active nucleus leak time and two dimension wind field calculate each grid cell concentration value；Letting out of above-mentioned radionuclide Leakage situation at least includes: be in long-term reveal and near the ground, be in long-term reveal and there is certain altitude on distance ground, is in short-term Reveal, be in complicated massif these four situation.

Here radionuclide leak time starts to calculate from initial time.

Step 5, concentration value according to each grid cell judge whether radioactivity cloud cluster divides, if it is not, enter step Six, if so, enter step 7；

If radioactivity cloud cluster is divided, then the center of each radioactivity cloud cluster after redefining division is needed to sit Mark.

Step 6, calculate new archicenter coordinate according to two dimension wind field, and enter step 4；

Step 7, determine the number of radioactivity cloud cluster, and calculate the archicenter coordinate of each radioactivity cloud cluster, according to step Rapid four calculate each radioactivity cloud cluster contribution margin to grid cell concentration；

Owing to there may be the most superimposed situation between radioactivity cloud cluster, the grid cell concentration at mutual superimposed place is just To consider each cloud cluster concentration influence value to it, the contribution to grid cell concentration of the most above-mentioned each radioactivity cloud cluster Value.

Step 8, the contribution margin of grid cell concentration is sued for peace by each radioactivity cloud cluster, obtain each grid cell dense Angle value；

Step 9, the step 7 that repeats, eight times preset until time arrival；

Step 10, setting concentration threshold, indicia grid unit concentration is more than the grid of threshold value；

Situation below threshold value then without the concern for because little concentration nucleic pollute human body will not be worked the mischief, Also allow for the computing capability of computer simultaneously.

Step 11, the concentration of the grid cell of labelling is mapped to rgb space, draws whole diffusion zone figure, obtain Whole radionuclide diffusion zone figure.

Mapped by texture and grid concentration value is transformed to rgb space, draw whole diffusion zone figure, use color gradient table Existing concentration gradually changes, and finally draws the whole diffusion zone of radionuclide.

The present invention uses radionuclide diffusion model, geospatial analysis, visualization technique, by obtaining incident point ground Reason data, analyze the feature of its topography and geomorphology, in conjunction with meteorological condition at that time, obtain wind field weather information, analyze the fortune of wind field Dynamic rule, determines diffusion model parameter values, uses diffusion model to calculate the radionuclide concentration of incident point surrounding Value, it was predicted that go out contaminated regional extent within the incident time period.Therefore the present invention is to occurring that uncontrollable nuclear accident is urgent In the case of, have and important instruct decision-making meaning.

Radionuclide diffusion model to be determined, determines that the source point that incident point generation radionuclide spreads is crucial, root According to geographical environment and the complex conditions of source point, in conjunction with wind field at that time.Geographical position residing for source point, decides used use Which kind of radionuclide diffusion model, and there is the position of nuclear accident, in the range of calculating, its topography and geomorphology decides diffusion Which kind of calculation is model parameter use obtain.Mathematical model for being used under various environment is attached to lower section, Primary Reference Monograph have: " Atmospheric Environmental Impact Assessment " that " nuclear environment basis " of Song Miaofa, Qiang Yizhong chief editor and virgin will power are write, Relevant basic formula derivation can check the books in terms of turbulence theory.

1. it is in long-term nuclear leakage, and time near the ground, radionuclide diffusion model is formula (1)

$C(x,y,z)=\frac{Q}{2\mathrm{\πu}{\mathrm{\σ}}_y{\mathrm{\σ}}_z}\·\exp [-\frac{1}{2}(\frac{y^2}{{{\mathrm{\σ}}_y}^2}+\frac{z^2}{{\mathrm{\σ}}_z})]---\left(1\right)$

Wherein, C is a p (x, y, z) mean concentration of radionuclide contamination thing at point, Bq m^-3；

Q is radionuclide release rate, Bq s^-1；Its mathematics computing model is formula (7).

σ_y, σ_zIt is lower wind direction x (m) distance cross-wind direction and the diffusion coefficient of vertical direction.Its mathematics computing model is formula (6).

2. it is in long-term nuclear leakage, and when overhead having certain altitude, radionuclide diffusion model is formula (2)

$C(x,y,z)=\frac{Q}{2\mathrm{\πu}{\mathrm{\σ}}_y{\mathrm{\σ}}_z}\·\exp (-\frac{y^2}{2{{\mathrm{\σ}}_y}^2})\left\{\exp \right[\left(\frac{-{(z-h)}^2}{2{{\mathrm{\σ}}_z}^2}\right)]+\exp [\left(\frac{-{(z+h)}^2}{2{{\mathrm{\σ}}_z}^2}\right)\left]\right\}---\left(2\right)$

Wherein, after h is radionuclide release, the Metacentre Height of radioactivity cloud cluster, m, its mathematics computing model is formula (8).

3. being in short-term nuclear leakage, radionuclide diffusion model is formula (3)

$C_i(x,y,z)=\frac{Q}{2{\mathrm{\π}}^{\frac{3}{2}}{\mathrm{\σ}}_x{\mathrm{\σ}}_y{\mathrm{\σ}}_z}\·\exp [-\frac{1}{2}{\left(\frac{x-x_c\left(i\right)}{{\mathrm{\σ}}_x}\right)}^2-\frac{1}{2}{\left(\frac{y-y_c\left(i\right)}{{\mathrm{\σ}}_y}\right)}^2].---\left(3\right)$

$\underset{n=-\∞}{\overset{\∞}{\mathrm{\Σ}}}\left\{\exp \right[-\frac{1}{2}{\left(\frac{z-z_c\left(i\right)+2n{z}_{\mathrm{inv}}}{{\mathrm{\σ}}_z\left(i\right)}\right)}^2]+\exp [-\frac{1}{2}{\left(\frac{z+z_c\left(i\right)+2n{z}_{\mathrm{inv}}}{{\mathrm{\σ}}_z}\right)}^2\left]\right\}$

Wherein, σ_x, σ_y, σ_zFor diffusion coefficient.Its mathematics computing model is formula (6)

x_c(i), y_x(i), z_cI () is i-th radionuclide diffused cloud centre coordinate, unit is m.Its mathematical calculation Model is formula (5).z_invThe height on top, by combining meteorological measuring, uses Yd method, Roche method or look-up table to obtain.n Span [1,4].

4., when being in complicated mountain relief, radionuclide diffusion model is formula (4)

$C^{\′}(x,y,z)=(0.5+\frac{{\∫}_0^{\mathrm{Hc}}{C}_s(x,y,z)\mathrm{dz}}{2{\∫}_0^{\∞}{C}_s(x,y,z)\mathrm{dz}})\·C(x,y,z)+(1-(0.5+\frac{{\∫}_0^{\mathrm{Hc}}{C}_s(x,y,z)\mathrm{dz}}{2{\∫}_0^{\∞}{C}_s(x,y,z)\mathrm{dz}}))\·C(x,y,z-z_t)---\left(4\right)$

Wherein C (x, y, z), C (x, y, z-z_t) it is to be tried to achieve by formula (1) or formula (2) or formula (3), z_tIt is that leeward connects Sink spatial concentration calculates spot projection to topographical surface, and at the horizontal elevation of spatial point corresponding to topographical surface, Hc is critical point Stream height.

5. Radionuclides Cloud centre coordinate mathematical model is formula (5),

$\left\{\begin{array}{c}{x}_c\left(i\right)=x_{c0}\left(i\right)+u_x\mathrm{\Δt}\\ y_c\left(i\right)=y_{c0}\left(i\right)+u_y\mathrm{\Δt}\\ z_c\left(i\right)=z_{c0}\left(i\right)+u_z\mathrm{\Δt}\end{array}\right.---\left(5\right)$

Wherein, mean wind speed u=(u_x, u_y, u_z), original position (x_c0(i), y_c0(i), z_c0(i)), Δ t is time interval.

6. σ_x, σ_y, σ_zDetermination for diffusion parameter uses Vogt method to calculate, for formula (6)

$\left\{\begin{array}{c}{\mathrm{\σ}}_x={\mathrm{\σ}}_y=a{x}^{b+c\ln x}\\ {\mathrm{\σ}}_z=d{x}^{e+f\·\ln x}\end{array}\right.---\left(6\right)$

Wherein, x unit is km, parameter a, and b, c, d, e, f, according to meteorological condition, inquire about national standard (GB/T13201- 1991) " formulate the technical method of local atmosphere pollutants emission standards " to obtain.

7. the release rate mathematics computing model of radionuclide is formula (7)

$Q=Q^{\′}\·\exp (-\frac{0.693t}{3600T_{0.5}})---\left(7\right)$

Wherein, Q ' is radionuclide initial release concentration, T_0.5For radionuclide halflife.

8. after Radionuclides Cloud release, heating power lifting etc. the Metacentre Height risen, mathematics computing model is formula (8)

$h=h^{\′}+1.44\·D_i{\left(\frac{W_0}{u}\right)}^{2/3}{\left(\frac{x}{D_i}\right)}^{2/3}-C---\left(8\right)$

Wherein, W₀Initiateing diffusion velocity for radionuclide, unit is m/s；H ' is radionuclide initial diffusion height, Unit is m；X is lower wind direction distance, and unit is m；U is that h ' locates mean wind speed, and unit is m/s；D_iExpand for radionuclide is initial Dissipating radius, unit is m；C is modifying factor, and unit is m.

The geographic information data that the calculating of radionuclide diffusion zone is related to, weather information data, radionuclide Physical characteristic, they influence each other, sufficiently complex to the diffusion zone accurately calculating radionuclide.In conjunction with Fig. 5 functional sequence Figure, is determined by thing time of origin, center, geographical terrain landforms, in conjunction with meteorological data, determines that radionuclide spreads mould The parameters of type, chooses the diffusion model under the orographic condition of correspondence.So far, calculating does not terminate, due to answering of parameter Polygamy and the uncertain row of wind field, need constantly to update wind field data, because center position has occurred and that change, diffusion office Portion the most tentatively establishes in region, in order to be computed correctly out the diffusion zone of next stage, and cannot be simply with diffusion above Model calculates, and the core calculations of the present invention makes full use of geodata exactly, in conjunction with Wind field variety, and dense primary Calculation Degree region divides, and is also required to first cloud cluster to split into little cloud cluster simultaneously, abstract is added in geographic grid, again Calculate the center of little cloud cluster.As shown in Figure 4, then use diffusion model gradually to calculate, finally corresponding result is entered Row superposition, can draw what radionuclide diffusion zone in the time range arranged, the evolving path, and diffusion were caused Pollution level.

The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, for the skill of this area For art personnel, the present invention can have various modifications and variations.All within the spirit and principles in the present invention, that is made any repaiies Change, equivalent, improvement etc., should be included within the scope of the present invention.

Claims (1)

1. the computational methods of a radionuclide diffusion, it is characterised in that including:

Step one, determine on map occur radionuclide reveal region, determine the archicenter coordinate of radioactivity cloud cluster；

Step 2, the region revealing generation radionuclide carry out geographic grid division, combined with hardware computing capability and display Effect determines suitable grid cell size；

Step 3, in each grid cell, carry out the two-dimentional wind field superposition of constant duration according to meteorological data；

Step 4, situation according to radionuclide leakage determine radionuclide diffusion model, and combine archicenter coordinate, Radionuclide leak time and two dimension wind field calculate each grid cell concentration value；

Step 5, concentration value according to each grid cell judge whether radioactivity cloud cluster divides, if it is not, enter step 6, if It is to enter step 7；

Step 6, calculate new archicenter coordinate according to two dimension wind field, and enter step 4；

Step 7, determine the number of radioactivity cloud cluster, and calculate the archicenter coordinate of each radioactivity cloud cluster, according to step 4 Calculate each radioactivity cloud cluster contribution margin to grid cell concentration；

Step 8, the contribution margin of grid cell concentration is sued for peace by each archicenter coordinate, obtain each grid cell concentration Value；

Step 9, judge whether arrive the setting time, if it is not, repeat step 7, eight until the time arrive preset times, if Enter step 10；

Step 10, setting concentration threshold, indicia grid unit concentration is more than the grid of threshold value；

Step 11, the concentration of the grid cell of labelling is mapped to rgb space, draws whole diffusion zone figure, obtain whole Radionuclide diffusion zone figure；

Wherein, in step 4, described radionuclide diffusion model is:

I. it is in long-term nuclear leakage, and time near the ground, radionuclide diffusion model is formula (1)

$C(x,y,z)=\frac{Q}{2{\mathrm{\πu\σ}}_y{\mathrm{\σ}}_z}\·\exp \[-\frac{1}{2}(\frac{y^2}{{{\mathrm{\σ}}_y}^2}+\frac{z^2}{{\mathrm{\σ}}_z})\]---\left(1\right)$

Wherein, C is that (x, y, z) mean concentration of radionuclide contamination thing at point, unit is Bq m to a p^-3；

Q is radionuclide release rate, and unit is Bq s^-1；Its mathematics computing model is formula (6)；

σ_y, σ_zIt is lower wind direction x (m) distance cross-wind direction and the diffusion coefficient of vertical direction；Its mathematics computing model is formula (6)；

II. it is in long-term nuclear leakage, and when overhead having certain altitude, radionuclide diffusion model is formula (2)

$C(x,y,z)=\frac{Q}{2{\mathrm{\πu\σ}}_y{\mathrm{\σ}}_z}\·\exp (-\frac{y^2}{2{{\mathrm{\σ}}_y}^2})\{\exp \[\left(\frac{-{(z-h)}^2}{2{{\mathrm{\σ}}_z}^2}\right)\]+\exp \[\left(\frac{-{(z+h)}^2}{2{{\mathrm{\σ}}_z}^2}\right)\]\}---\left(2\right)$

Wherein, after h is radionuclide release, the Metacentre Height of radioactivity cloud cluster, unit is m, and its mathematics computing model is formula (7)；

III. being in short-term nuclear leakage, radionuclide diffusion model is formula (3)

$\begin{array}{c}{C}_i(x,y,z)=\frac{Q}{2{\mathrm{\π}}^{\frac{3}{2}}{\mathrm{\σ}}_x{\mathrm{\σ}}_y{\mathrm{\σ}}_z}\·\exp (-\frac{1}{2}{\left(\frac{x-x_c\left(i\right)}{{\mathrm{\σ}}_x}\right)}^2-\frac{1}{2}{\left(\frac{y-y_c\left(i\right)}{{\mathrm{\σ}}_y}\right)}^2\]\\ \underset{n=-\mathrm{\∞}}{\overset{\mathrm{\∞}}{\mathrm{\Σ}}}\{\exp \[-\frac{1}{2}{\left(\frac{z-z_c\left(i\right)+2{\mathrm{nz}}_{inv}}{{\mathrm{\σ}}_z\left(i\right)}\right)}^2\]+\exp \[-\frac{1}{2}{\left(\frac{z+z_c\left(i\right)+2{\mathrm{nz}}_{inv}}{{\mathrm{\σ}}_z}\right)}^2\]\}\end{array}.---\left(3\right)$

Wherein, σ_x, σ_y, σ_zFor diffusion coefficient；Its mathematics computing model is formula (5)

x_c(i), y_x(i), z_cI () is i-th radionuclide diffused cloud centre coordinate, unit is m, its mathematics computing model For formula (4), z_invFor the height on inversion layer top, by combining meteorological measuring, Yd method, Roche method or look-up table is used to obtain Take, the span [Isosorbide-5-Nitrae] of n；

IV. Radionuclides Cloud centre coordinate mathematical model is formula (4),

$\left\{\begin{array}{c}{x}_c\left(i\right)=x_{c0}\left(i\right)+u_x\mathrm{\Δ}t\\ y_c\left(i\right)=y_{c0}\left(i\right)+u_y\mathrm{\Δ}t\\ z_c\left(i\right)=z_{c0}\left(i\right)+u_z\mathrm{\Δ}t\end{array}\right.---\left(4\right)$

Wherein, mean wind speed u=(u_x, u_y, u_z), original position (x_c0(i), y_c0(i), z_c0(i)), Δ t is time interval；

Ⅴ.σ_x, σ_y, σ_zDetermination for diffusion parameter uses Vogt method to calculate, for formula (5)

$\left\{\begin{array}{c}{\mathrm{\σ}}_x={\mathrm{\σ}}_y={\mathrm{ax}}^{b+clnx}\\ {\mathrm{\σ}}_z={\mathrm{dx}}^{e+f\·\ln x}\end{array}\right.---\left(5\right)$

Wherein, x unit is km, parameter a, and b, c, d, e, f are according to meteorological condition, inquiry national standard " GB/T13201-1991 " " formulating the technical method of local atmosphere pollutants emission standards " obtains；

VI. the release rate mathematics computing model of radionuclide is formula (6)

$Q=Q^{\′}\·\exp (-\frac{0.693t}{3600T_{0.5}})---\left(6\right)$

Wherein, Q' is radionuclide initial release concentration, T_0.5For radionuclide halflife；

VII. after Radionuclides Cloud release, heating power lifting etc. the Metacentre Height risen, mathematics computing model is formula (7)

$h=h^{\′}+1.44\·D_i{\left(\frac{W_0}{u}\right)}^{2/3}{\left(\frac{x}{D_i}\right)}^{2/3}-C---\left(7\right)$

Wherein, W₀Initiateing diffusion velocity for radionuclide, unit is m/s；H' is radionuclide initial diffusion height, unit For m；X is lower wind direction distance, and unit is m；U is mean wind speed at h', and unit is m/s；D_iFor the initial diffusion of radionuclide half Footpath, unit is m；C is modifying factor, and unit is m.