CN103413062A - Computing method of diffusion of radionuclides - Google Patents

Abstract

The invention relates to a computing method of diffusion of radionuclides. According to the method, geographic grid cells are divided in a diffusion area of a radioactive cloud, a two-dimensional wind field is overlaid on the grid cells, and a correlation model is used for simulating the moving and developing process of the radioactive cloud and the influence range and the radioactive concentration of the radioactive cloud after a preset time are finally obtained. By using the computing method of the diffusion of the radionuclides, the diffusion tendency in the atmosphere of radionuclide leakage caused by gusty serious nuclear accidents can be predicted, and the diffusion range of the radionuclides can be further confirmed.

Description

A kind of computing method of radioactive nuclide diffusion

Technical field

The present invention relates to the environmental pollution treatment field, be specifically related to a kind of computing method of radioactive nuclide diffusion.

Background technology

Nuclear energy more and more is subject to people's favor as a kind of clean, safe energy, utilizes more and more extensive.The history of nuclear power station development is verified, and the safety record of nuclear power station is good.But modern science and technology can not definitely be got rid of the possibility that serious nuclear accident occurs.The nuclear accident caused as the manual operation fault: the serious nuclear leakage that U.S.'s Three Mile Island nuclear reactor in 1973 occurs, and more serious No. 4, Chernobyl Plants in 1986 reactor is blasted, cause 30 people to die instantly, intense radiation thing more than 8 tons leaks, around power station, more than 60,000 square kilometre of soil is subject to direct pollution, more than 320 ten thousand people are subject to the nuclear radiation infringement, disaster causes Fukushima, Japan nuclear power station blast in 2011 for another example, a large amount of nuclear radiation are diffused into outside, and human habitat and healthy and safe in serious threat.

Nuclear energy is not only and can be used as the energy, also can be taken as weapon and use in battlefield, and as in World War II, 2 atomic bombs have been thrown to Japan by the U.S., and the radioactive nuclide that nuclear explosion produces is in middle atmospheric diffusion, the long-term impact brought to surrounding enviroment.For serious nuclear accident, what harm was maximum is the diffusion of the radioactive nuclide of nuclear explosion or nuclear leakage generation, in the diffusion zone scope, and the people's health and safety around having a strong impact on.

Occurring in this uncontrollable nuclear accident situation, for life and health and the safety of the people around protection nuclear accident point, need to take necessary measure, the number of casualties is being dropped to minimum.Before this, determine the pollution range zone of radioactive nuclide diffusion, prediction is in after a while, and the regional extent that radioactive nuclide can be diffused into becomes a difficult problem urgently to be resolved hurrily at present.

At present, in the nuclear accident in correlation technique, model of atmospheric diffusion mainly contains three classes, and namely Lagrangian cigarette is rolled into a ball model, Gaussian plume model and Three-dimensional numerical calculation model.Due in the nuclear explosion accident, atmosphere is in an unsure state, and Gaussian plume model is to suppose that it is prerequisite that atmosphere is in steady state (SS), therefore use Gaussian plume model and be not suitable for, and Three-dimensional numerical calculation model calculated amount is excessive, expend time in longer, in practice, be difficult to meet the demands, although Lagrange cigarette group model can calculate the spatial and temporal distributions of radiomaterial in propagation in atmosphere comparatively really at complex condition, but traditional disposal route is the cigarette group that processes continuous release, for uncontrollable serious nuclear accident condition, be difficult to be suitable for.

Summary of the invention

In view of this, the invention provides a kind of computing method of radioactive nuclide diffusion, can predict that the caused radioactive nuclide of serious nuclear accident of burst is revealed the diffusion tendency in atmosphere, and then the range of scatter of definite radioactive nuclide.

Concrete scheme of the present invention is such: a kind of computing method of radioactive nuclide diffusion comprise:

Step 1, the zone that radioactive nuclide is revealed determine occurring on map, determines the archicenter coordinate of radioactivity cloud cluster;

Step 2, carry out the geographic grid division to the zone that radioactive nuclide reveals occurs, combined with hardware computing power and display effect are determined suitable grid cell size;

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

Step 4, the situation of leaking according to radioactive nucleus are determined the radioactive nuclide diffusion model, and are calculated each grid cell concentration value in conjunction with archicenter coordinate, active nucleus leak time and two-dimentional wind field;

Step 5, according to the concentration value of each grid cell, judge whether the radioactivity cloud cluster divides, and if not, enters step 6, if enter step 7;

Step 6, calculate new archicenter coordinate according to two-dimentional 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, calculate the contribution margin of each radioactivity cloud cluster to grid cell concentration according to step 4;

Step 8, to each radioactivity cloud cluster to the summation of the contribution margin of grid cell concentration, obtain each grid cell concentration value;

Step 9, repeating step seven, eight are until the time default time of arrival;

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

Step 11, the concentration of the grid cell of mark is mapped to rgb space, draws whole diffusion zone figure, obtain whole radioactive nuclide diffusion zone figure.

Beneficial effect:

The present invention adopts radioactive nuclide diffusion model, geographical space analysis, visualization technique, by obtaining incident point geodata, analyze the characteristics of its topography and geomorphology, in conjunction with meteorological condition at that time, obtain the wind field weather information, analyze the characteristics of motion of wind field, determine the diffusion model parameter values, use diffusion model to calculate the radionuclide concentration value of incident point surrounding environment, dope contaminated regional extent within the incident time period.Therefore the present invention is to uncontrollable nuclear accident occurring in emergency circumstances, has the important decision-making meaning that instructs.

The accompanying drawing explanation

Fig. 1 is the process flow diagram of the computing method of radioactive nuclide diffusion of the present invention;

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

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

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

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

Embodiment

The invention provides the computing method of a kind of radioactive nuclide diffusion, as Fig. 1～shown in Figure 5, comprising:

Step 1, the zone that radioactive nuclide is revealed determine occurring on map, determines the archicenter coordinate of radioactivity cloud cluster;

Determining of archicenter coordinate is very important, carries it in Radionuclides Cloud centre coordinate mathematical model and just can try to achieve new centre coordinate.

Step 2, carry out the geographic grid division to the zone that radioactive nuclide reveals occurs, combined with hardware computing power and display effect are determined suitable grid cell size;

The result of dividing wants to reflect rightly the change procedure of radioactivity cloud cluster, considers simultaneously the computing power of computer hardware, makes the smoothness of system operation.

Step 3, according to weather data, carry out the two-dimentional wind field stack of constant duration in each grid cell; Because wind field is constantly to change, need constantly to upgrade the wind field data.The two-dimentional wind field stack here specifically refers to: according to the corresponding geographical locational two-dimentional wind field of each grid institute by its grid that is added to.

Step 4, determine the radioactive nuclide diffusion model according to the leakage situation of radioactive nuclide, and calculate each grid cell concentration value in conjunction with archicenter coordinate, active nucleus leak time and two-dimentional wind field; The leakage situation of above-mentioned radioactive nuclide comprises at least: be in long-term leakage and near the ground, be in long-term leakage and certain altitude arranged, be in short-term and reveal, be in these four kinds of situations of complicated massif apart from ground.

The radioactive nuclide leak time here starts to calculate from initial time.

Step 5, according to the concentration value of each grid cell, judge whether the radioactivity cloud cluster divides, and if not, enters step 6, if enter step 7;

If the radioactivity cloud cluster divides, need to redefine the centre coordinate of each the radioactivity cloud cluster after division.

Step 6, calculate new archicenter coordinate according to two-dimentional 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, calculate the contribution margin of each radioactivity cloud cluster to grid cell concentration according to step 4;

Owing between the radioactivity cloud cluster, may having the situation of mutual stack, in the grid cell concentration of stack place mutually, will consider the concentration affects value of each cloud cluster to it, i.e. the contribution margin of each above-mentioned radioactivity cloud cluster to grid cell concentration.

Step 8, to each radioactivity cloud cluster to the summation of the contribution margin of grid cell concentration, obtain each grid cell concentration value;

Step 9, repeating step seven, eight are until the time default time of arrival;

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

Situation below threshold value does not need to consider, because polluting, the nucleic of small concentration can not work the mischief to human body, and be also the computing power of considering computing machine simultaneously.

Step 11, the concentration of the grid cell of mark is mapped to rgb space, draws whole diffusion zone figure, obtain whole radioactive nuclide diffusion zone figure.

By texture, the grid concentration value is transformed to rgb space, draw whole diffusion zone figure, gradually change by color gradient performance concentration, finally draw the whole diffusion zone of radioactive nuclide.

The present invention adopts radioactive nuclide diffusion model, geographical space analysis, visualization technique, by obtaining incident point geodata, analyze the characteristics of its topography and geomorphology, in conjunction with meteorological condition at that time, obtain the wind field weather information, analyze the characteristics of motion of wind field, determine the diffusion model parameter values, use diffusion model to calculate the radionuclide concentration value of incident point surrounding environment, dope contaminated regional extent within the incident time period.Therefore the present invention is to uncontrollable nuclear accident occurring in emergency circumstances, has the important decision-making meaning that instructs.

Determine the radioactive nuclide diffusion model, determine that the source point of incident point generation radioactive nuclide diffusion is crucial, according to geographical environment and the complex conditions of source point, in conjunction with wind field at that time.The residing geographic position of source point, determining which kind of radioactive nuclide diffusion model of the use adopted, and the position of nuclear accident occurs, and in the scope of calculating, its topography and geomorphology is determining which kind of account form is the diffusion model parameter adopt obtain.For the mathematical model of using under various environment, be attached to below, the monograph of main reference has: Song Miaofa, Qiang Yizhong chief editor's " nuclear environment is learned basis " and " Atmospheric Environmental Impact Assessment " that Tong Zhiquan writes, relevant basic formula is derived and can be checked the books of turbulence theory aspect.

1. be in long-term nuclear leakage, and when near the ground, the radioactive nuclide diffusion model is formula (1)

$C(x,y,z)=\frac{\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="DEST\_PATH\_EDA00003744318200011.png"\; state="\{\{state\}\}">Q</figure-callout>}}{2\mathrm{\&pi;u}{\mathrm{\&sigma;}}_y{\mathrm{\&sigma;}}_z}\&CenterDot;\exp [-\frac{1}{2}(\frac{y^2}{{{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="DEST\_PATH\_EDA00003744318200011.png"\; state="\{\{state\}\}">y</figure-callout>}}}^2}+\frac{{\mathrm{<figure-callout\; id="2"\; label="z"\; filenames="DEST\_PATH\_EDA00003744318200011.png"\; state="\{\{state\}\}">z</figure-callout>}}^2}{{\mathrm{\&sigma;}}_z})]---\left(1\right)$

Wherein, C is the mean concentration of a p (x, y, z) some place radionuclide contamination thing, Bqm ^-3

Q is the radioactive nuclide release rate, Bqs ^-1Its mathematics computing model is formula (7).

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

2. be in long-term nuclear leakage, and while overhead certain altitude being arranged, the radioactive nuclide diffusion model is formula (2)

$C(x,y,z)=\frac{\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="DEST\_PATH\_EDA00003744318200011.png"\; state="\{\{state\}\}">Q</figure-callout>}}{2\mathrm{\&pi;u}{\mathrm{\&sigma;}}_y{\mathrm{\&sigma;}}_z}\&CenterDot;\exp (-\frac{{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="DEST\_PATH\_EDA00003744318200011.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}{2{{\mathrm{\&sigma;}}_y}^2})\left\{\exp \right[\left(\frac{-{(z-h)}^2}{2{{\mathrm{\&sigma;}}_z}^2}\right)]+\exp [\left(\frac{-{(z+h)}^2}{2{{\mathrm{\&sigma;}}_z}^2}\right)\left]\right\}---\left(2\right)$

Wherein, h is that after radioactive nuclide discharged, the Metacentre Height of radioactivity cloud cluster, m, its mathematics computing model were formula (8).

3. be in the short-term nuclear leakage, the radioactive nuclide diffusion model is formula (3)

$C_i(x,y,z)=\frac{\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="DEST\_PATH\_EDA00003744318200011.png"\; state="\{\{state\}\}">Q</figure-callout>}}{2{\mathrm{\&pi;}}^{\frac{3}{2}}{\mathrm{\&sigma;}}_x{\mathrm{\&sigma;}}_y{\mathrm{\&sigma;}}_z}\&CenterDot;\exp [-\frac{1}{2}{\left(\frac{x-x_c\left(i\right)}{{\mathrm{\&sigma;}}_x}\right)}^2-\frac{1}{2}{\left(\frac{y-y_c\left(i\right)}{{\mathrm{\&sigma;}}_y}\right)}^2].---\left(3\right)$

$\underset{n=-\&infin;}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\left\{\exp \right[-\frac{1}{2}{\left(\frac{z-z_c\left(i\right)+2n{z}_{\mathrm{inv}}}{{\mathrm{\&sigma;}}_z\left(i\right)}\right)}^2]+\exp [-\frac{1}{2}{\left(\frac{z+z_c\left(i\right)+2n{z}_{\mathrm{inv}}}{{\mathrm{\&sigma;}}_z}\right)}^2\left]\right\}$

Wherein, σ _x, σ _y, σ _zFor coefficient of diffusion.Its mathematics computing model is formula (6)

X _c(i), y _x(i), z _c(i) be i radioactive nuclide diffused cloud centre coordinate, unit is m.Its mathematics computing model is formula (5).

For the height on inversion layer top, by conjunction with meteorological measuring, adopt Yd method, Luo Shi method or look-up table to obtain.The span of n [Isosorbide-5-Nitrae].

4. while being in complicated mountain relief, the radioactive nuclide diffusion model is formula (4)

$C^{\&prime;}(x,y,z)=(0.5+\frac{{\&Integral;}_0^{\mathrm{Hc}}{C}_s(x,y,z)\mathrm{dz}}{2{\&Integral;}_0^{\&infin;}{C}_s(x,y,z)\mathrm{dz}})\&CenterDot;C(x,y,z)+(1-(0.5+\frac{{\&Integral;}_0^{\mathrm{Hc}}{C}_s(x,y,z)\mathrm{dz}}{2{\&Integral;}_0^{\&infin;}{C}_s(x,y,z)\mathrm{dz}}))\&CenterDot;C(x,y,z-z_t)---\left(4\right)$

Wherein C (x, y, z), C (x, y, z-z _t) be to be tried to achieve by formula (1) or formula (2) or formula (3), z _tBe that leeward acceptance point spatial concentration calculation level projects to topographical surface, at the horizontal elevation of spatial point corresponding to topographical surface, Hc is critical shunting height.

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

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

Wherein, mean wind speed u=(u _x, u _y, u _z), reference position (x _C0(i), y _C0(i), z _C0(i)), Δ t is the time interval.

6. σ _x, σ _y, σ _zFor definite employing Vogt method of diffusion parameter, calculate, be formula (6)

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

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

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

$Q=Q^{\&prime;}\&CenterDot;\exp (-\frac{0.693t}{3600T_{0.5}})---\left(7\right)$

Wherein, Q ' is radioactive nuclide initial release concentration, T _0.5For radionuclide halflife.

8. after Radionuclides Cloud discharged, by the Metacentre Height of the risings such as heating power lifting, mathematics computing model was formula (8)

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

Wherein, W ₀For the initial rate of propagation of radioactive nuclide, unit is m/s; H ' is the initial diffusion height of radioactive nuclide, and 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 _iFor the initial diffusion radius of radioactive nuclide, unit is m; C is modifying factor, and unit is m.

To the geographic information data that the calculating of radioactive nuclide diffusion zone relates to, the weather information data, the radioactive nuclide physical characteristics, they influence each other, very complicated to the diffusion zone of accurate calculating radioactive nuclide.In conjunction with Fig. 5 functional flow diagram, the time occurs by determining thing, center, the geographical terrain landforms, in conjunction with weather data, determine the parameters of radioactive nuclide diffusion model, chooses the diffusion model under corresponding topographic condition.So far, do not calculate and finish, due to the complicacy of parameter and the uncertain row of wind field, need constantly to upgrade the wind field data, because center position changes, the diffusion regional area is tentatively established, in order correctly to calculate the diffusion zone of next stage, just can not simply with top diffusion model, calculate, core calculations of the present invention takes full advantage of geodata exactly, in conjunction with wind field, change, the concentration range of primary Calculation is divided, simultaneously also need first cloud cluster is split into to little cloud cluster, in the abstract geographic grid that is added to, recalculate the center of little cloud cluster.As shown in Figure 4, then use diffusion model successively to calculate, finally corresponding result is superposeed, can draw radioactive nuclide diffusion zone in the time range arranged, the evolving path, and spread the pollution level caused.

The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, for a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any modification of doing, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.

Claims (1)

1. the computing method of a radioactive nuclide diffusion, is characterized in that, comprising:

Step 1, the zone that radioactive nuclide is revealed determine occurring on map, determines the archicenter coordinate of radioactivity cloud cluster;

Step 2, carry out the geographic grid division to the zone that radioactive nuclide reveals occurs, combined with hardware computing power and display effect are determined suitable grid cell size;

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

Step 4, the situation of leaking according to radioactive nuclide are determined the radioactive nuclide diffusion model, and are calculated each grid cell concentration value in conjunction with archicenter coordinate, radioactive nuclide leak time and two-dimentional wind field;

Step 5, according to the concentration value of each grid cell, judge whether the radioactivity cloud cluster divides, and if not, enters step 6, if enter step 7;

Step 6, calculate new archicenter coordinate according to two-dimentional 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, calculate the contribution margin of each radioactivity cloud cluster to grid cell concentration according to step 4;

Step 8, to each archicenter coordinate to the summation of the contribution margin of grid cell concentration, obtain each grid cell concentration value;

Step 9, judge whether to arrive setting-up time, if not, repeating step seven, eight until the time arrive the default time, if the step 10 of entering;

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

Step 11, the concentration of the grid cell of mark is mapped to rgb space, draws whole diffusion zone figure, obtain whole radioactive nuclide diffusion zone figure.

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