CN112000922A - Special nuclide radiation environment influence evaluation system for post-treatment plant - Google Patents

Abstract

The invention discloses a system for evaluating the influence of special nuclide radiation environment of a post-treatment plant, which comprises: the special nuclide basic information module is used for storing basic information of each special nuclide; the field address characteristic data module is used for storing field address basic information; the nuclide release source item module is used for storing release parameters and pollutant parameters; the atmospheric diffusion module is used for calling parameters of the site characteristic data module and the nuclide release source item module, calculating by corresponding calculation formulas and then outputting atmospheric diffusion factors and nuclide ambient air concentration; the environment medium special nuclide concentration calculation module is used for calling parameters of the atmospheric diffusion module and the nuclide release source item module, internally setting evaluation parameters and calculating the concentration of the special nuclide in soil, plant products and animal products; and the nuclide dose evaluation result output module is used for calculating the public dose caused by each special nuclide. The invention can realize the public radiation dose evaluation of the key pollutant emission of the post-treatment plant.

Description

Special nuclide radiation environment influence evaluation system for post-treatment plant

Technical Field

The invention relates to the field of radiation environment influence evaluation, in particular to a radiation environment influence evaluation system for special nuclides in a post-treatment plant.

Background

The main process of nuclear fuel post-treatment is a PUREX process, and the waste fuel can generate radioactive waste gas in the processes of shearing, dissolving, waste liquid evaporation, treatment and the like. The statistics data of the committee on atomic radiation effect of the united nations show that: 1998 + 2002 air-load of post-treatment plant³H release amount of 2001TBq, liquid state³The H release amount is 84473 TBq; airborne¹⁴C release of 44.16TBq in liquid form¹⁴The C release amount is 105.5 TBq; airborne⁸⁵The Kr release amount is 2.16X 10⁶TBq; airborne¹²⁹I release amount of 0.14TBq, liquid state¹²⁹The I release was 12.18 TBq. Thus, T is shown in the post-treatment process,¹⁴C、⁸⁵Kr and¹²⁹i nuclides are contributors to major emissions.

T、¹⁴C is the most ubiquitous element in living cells compared to other nuclides, and is easily enriched and exchanged in vivo, and public doses due to different chemical forms of T, such as inorganic tritium HTO and organic tritium OBT, need to be considered.¹²⁹I has a long half-life of 1570 ten thousand years, and enters human body to be selectively enriched in thyroid gland, so that¹²⁹I should focus on the intrathyroid irradiation.⁸⁵Kr belongs to radioactive inert gas nuclide, which rapidly diffuses in the atmosphere and cannot be absorbed by the human body, and mainly generates external irradiation to the human body. As can be seen, T is,¹⁴C、⁸⁵Kr and¹²⁹the existing form and migration behavior of the I nuclear species in the environment are different from those of other nuclear species, so that the special nuclear species T, T,¹⁴C、⁸⁵Kr and¹²⁹i migration rule and evaluation method.

And establishing a special nuclide evaluation system to evaluate the dosage of the nuclide which mainly contributes to the environmental impact evaluation of the post-treatment plant. The method is suitable for post-treatment plants and the like involving the following four radionuclides T,¹⁴C、⁸⁵Kr and¹²⁹i nuclear facilities for discharge. At present, the post-treatment facilities in China are still in the initial research stage, and an evaluation system of special nuclides is not established yet. Differences in migration behavior of different specific nuclides, differences in nuclide properties, lead to differences in evaluation patterns and in the human critical illuminated pathways.

In order to solve the problem of effective evaluation of public radiation influence caused by nuclide release of effluents of a post-treatment plant in the future, the invention aims to establish a special nuclide radiation environment influence evaluation system of the post-treatment plant, determine main radiation dose sources of nuclides through migration behavior research and key path identification of the special nuclides, obtain evaluation modes of different nuclides and establish an evaluation system of the special nuclides of the post-treatment plant.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a special nuclide radiation environment influence evaluation system for an after-treatment plant, which can realize public radiation dose evaluation of key pollutant emission of the after-treatment plant.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a post-treatment plant special nuclide radiation environment influence evaluation system comprises:

the special nuclide basic information module is used for storing basic information of each special nuclide, wherein the basic information comprises the half-life period, the decay constant and the dose conversion factor of each special nuclide; the method is also used for screening public key irradiation ways caused by each special nuclide according to the property of each special nuclide;

the site characteristic data module is used for storing site basic information, and the site basic information comprises plant site environment parameters and population recipe parameters;

the nuclide release source item module is used for storing release parameters and pollutant parameters;

the atmospheric diffusion module is used for calling parameters of the site characteristic data module and the nuclide release source item module, outputting atmospheric diffusion factors and nuclide ambient air concentration after calculation through corresponding calculation formulas, and determining to use different calculation formulas according to the height of the emission source, the height of the highest building adjacent to the emission source and the distance between the receiving point and the emission point;

the environment medium special nuclide concentration calculation module is used for calling parameters of the atmospheric diffusion module and the nuclide release source item module, internally setting evaluation parameters and calculating the concentration of special nuclides in soil, plant products and animal products;

and the nuclide dose evaluation result output module is used for calling all information parameters in the special nuclide basic information module, the site characteristic data module, the nuclide release source item module, the atmospheric diffusion module and the environment medium special nuclide concentration calculation module and calculating the public dose caused by each special nuclide based on the screened key irradiation way of the public caused by each special nuclide.

Further, as described above, the system for evaluating the influence of the radiation environment of the special nuclide in the post-processing plant, the special nuclide basic information module, the site characteristic data module, the nuclide release source item module, the atmospheric diffusion module, the ambient medium special nuclide concentration calculation module, and the nuclide dose evaluation result output module are further configured to: managing various data stored by the system, including inputting, modifying, exporting and inquiring, and outputting relevant data according to the radiation environment influence evaluation requirement.

Further, the evaluation system for the radiation environment influence of the special nuclide in the post-processing plant as described above, the plant site environment parameters include an average wind speed and a stability at a release height, the population recipe parameters include a plant site evaluation range population distribution and a plant site recipe data, and the plant site recipe data include the yield of food in a plant site area, the food intake of different types of food, and the intake share of an evaluation area;

the release parameters comprise a release chimney number, a chimney height, an exhaust rate and a height of an adjacent building, and the pollution source parameters comprise a nuclide name and an annual release amount.

Further, as to the system for evaluating the influence of the radiation environment of the special nuclide in the aftertreatment plant, the atmospheric diffusion module is specifically configured to:

1) if the height H of the emission source is greater than 2.5 times the height H of the next highest building_bI.e. H > 2.5H_bThen, the atmospheric diffusion factor is calculated by the following formula:

C_air，i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³(ii) a i is a nuclide T,¹⁴C、⁸⁵Kr or¹²⁹I；

Q_i: the release rate of the nuclide i, Bq/s;

D_i: atmospheric diffusion factor, s/m, of nuclide i³；

P_p: the time share of the fan-shaped direction p of the wind blowing to the receiving point in one year is 0.25;

f: releasing a Gaussian diffusion factor of height, namely emission source height H, 1/m at a downwind distance release point x²；

u_a: annual average wind speed, m/s, over the release height;

h: emission source height, m;

H_b: height of adjacent highest building, m;

x: distance, m, from the release point to the calculation point;

u in the formula (1) is obtained by the following formula calculation_a：

u₁₀: the wind speed at the height of 10m from the ground is m/s;

h: emission source height, m;

n: a wind profile coefficient;

f in formula (1) is calculated by the following formula:

x: distance, m, from the release point to the calculation point;

σ_z: vertical diffusion parameter, m;

if H is less than or equal to 45m, the formula (3) is

2) If the height H of the emission source is less than or equal to 2.5H_bAnd is and

the atmospheric diffusion factor is calculated by the following formula:

C_air，i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³(ii) a I is nuclide T, 14C, 85Kr or 129I;

Q_i: the release rate of the nuclide i, Bq/s;

D_i: atmospheric diffusion factor, s/m, of nuclide i³；

P_p: the time share of the fan-shaped direction p of the wind blowing to the receiving point in one year is 0.25;

b: gauss diffusion factor at downwind distance x, 1/m²；

u_a: annual average wind speed, m/s, over the release height;

h: emission source height, m;

H_b: height of adjacent highest building, m;

A_b: cross sectional area, m, adjacent to the highest building²；

x: distance, m, from the release point to the calculation point;

b in formula (4) is calculated by the following formula:

σ_z: vertical diffusion parameter, m;

A_b: cross sectional area, m, adjacent to the highest building²；

x: distance, m, from the release point to the calculation point;

3) if the height H of the emission source is less than or equal to 2.5H_bAnd is and

and if the receiving point is not on the surface of the building where the releasing point is located, calculating the atmospheric diffusion factor by the following formula:

C_air，i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³(ii) a I is nuclide T, 14C, 85Kr or 129I;

Q_i: the release rate of the nuclide i, Bq/s;

D_i: atmospheric diffusion factor, s/m, of nuclide i³；

P_p: the time share of the fan-shaped direction p of the wind blowing to the receiving point in one year is 0.25;

u_a: annual average wind speed, m/s, over the release height;

k: taking an empirical constant of 1 m;

h: emission source height, m;

H_b: height of adjacent highest building, m;

A_b: cross sectional area, m, adjacent to the highest building²；

x: distance, m, of the release point to the calculation point.

Further, as described above, the system for evaluating the influence of the radiation environment of the special nuclide in the post-processing plant, the module for calculating the concentration of the special nuclide in the environment medium is specifically configured to: calculating the concentration of HTO in soil, the concentration of HTO in plant products, the concentration of HTO in drinking water and forage water, the concentration of HTO in terrestrial animal and plant products, the concentration of OBT in terrestrial products and the concentration of OBT in animal products;

1) the HTO concentration in the soil is calculated by the following formula:

C_sw，HTO(x) The method comprises the following steps The concentration of HTO in the soil water at a distance x from the release point, Bq/L;

CR_s-a: an empirical constant;

C_air，HTO(x) The method comprises the following steps Concentration of HTO in air, Bq/m, at a distance x from the release point³；

H_a: absolute humidity, L/m³；

x: distance, m, from the release point to the calculation point;

2) the HTO concentration in the plant product was calculated by the following formula:

C_f，HTO(x) The method comprises the following steps The concentration of HTO in the plant product at a distance x from the release point, fresh weight, Bq/kg;

WC_P: water content of the plant, fresh weight, L/kg;

RH: relative humidity;

C_air，HTO(x) The method comprises the following steps Concentration of HTO in air, Bq/m, at a distance x from the release point³；

H_a: absolute humidity, L/m³；

C_sw，HTO(x) The method comprises the following steps The concentration of HTO in the soil water at a distance x from the release point, Bq/L;

γ: the ratio of the HTO saturated vapor pressure in water;

x: distance, m, from the release point to the calculation point;

3) the HTO concentration in the drinking water and the forage water is calculated by the following formula:

CR_f，HTO(x) The method comprises the following steps HTO concentration in drinking/forage water (assuming 50% intake from drinking water, 50% from forage), Bq/L;

C_sw，HTO(x) The method comprises the following steps The concentration of HTO in the soil water at a distance x from the release point, Bq/L;

C_{pasture，HTO}(x) The method comprises the following steps The concentration of HTO in the soil water at a distance x from the release point, Bq/kg;

WC_P: water content (fresh weight) of the plant, L/kg;

x: distance, m, from the release point to the calculation point;

4) the HTO concentration in the terrestrial plant product is calculated by the following formula:

C_f，HTO(x)＝CR_a，HTO·CR_f，HTO(x) (11)

C_f，HTO(x) The method comprises the following steps HTO concentration in the terrestrial plant product, Bq/kg;

CR_a，HTO(x) The method comprises the following steps The ratio of the activity concentration of the ingested HTO in the absorption of water and tritium is L/kg;

x: distance, m, from the release point to the calculation point;

5) the concentration of OBT in the terrestrial product is calculated by the following formula:

C_f，OBT(x) The method comprises the following steps The concentration of OBT in the animal product, Bq/kg;

WC_P: water content (fresh weight) of the plant, L/kg;

WEQ_P: water equivalent factor, L/kg;

R_p: a branching factor;

C_f，HTO(x) The method comprises the following steps The concentration of HTO in the plant product, Bq/kg;

x: distance, m, from the release point to the calculation point;

6) the concentration of OBT in the animal product is calculated by the following formula:

C_f，OBT(x)＝CR_a，OBT·C_{pasture，OBT}(x) (13)

C_f，OBT(x) The method comprises the following steps The concentration of OBT in the animal product, Bq/kg;

CR_a，OBT(x) The method comprises the following steps The ratio of the activity concentration of ingested OBT in the feed tritium, L/kg;

C_{pasture，OBT}(x) The method comprises the following steps The average concentration of OBT in the feed, Bq/kg;

x: distance, m, of the release point to the calculation point.

Further, as described above, the system for evaluating the influence of the radiation environment of the special nuclide in the post-processing plant, the module for calculating the concentration of the special nuclide in the environment medium is specifically configured to: calculating plant products¹⁴C concentration, polluted river water irrigation plant product¹⁴C concentration and animal product¹⁴C concentration;

1) plant products¹⁴C concentration, calculated by the formula:

C_air，14C(x) The method comprises the following steps C-14 concentration at a distance x from the release point, Bq/m 3;

S_p: the concentration of stable carbon in the plant product, g C/kg fresh weight;

S_air: concentration of stable carbon in air, g C/m³；

SA_air: plant product specific activity Bq/g C;

x: distance, m, from the release point to the calculation point;

2) irrigation plant product for polluted river water¹⁴C concentration, calculated by the formula:

SA_air: plant product specific activity Bq/g C;

CD_s: a dilution factor, taking a value of 0.15;

I_irr: irrigation rate, 0.005m³/m²；

C_uw，s: activity concentration of nuclides in water, Bq/m³；

Fc: the rate of carbon production from decomposition of plant product residue, 0.66(g C)/m²；

x: distance, m, from the release point to the calculation point;

3) animal product¹⁴C concentration, calculated by the formula:

f_C：¹⁴c, taking 1 as a default value for the feeding share of the feed;

C_{pasture，14C}(x) The method comprises the following steps C-14 concentration in the forage at a distance x from the release point;

S_a: concentration of stable carbon in animal product, fresh weight, g C/kg;

S_p: the concentration and fresh weight of stable carbon in the forage are g C/kg;

x: distance, m, of the release point to the calculation point.

Further, as described above, the system for evaluating the influence of the radiation environment of the special nuclide in the post-processing plant, the module for calculating the concentration of the special nuclide in the environment medium is specifically configured to: nucleic acids in computing environment media¹²⁹The concentration of I is calculated by the following formula:

C_f，i(x)＝C_f，unit，i·d_i(x) (17)

d_i(x)＝V_TC_air，i(x) (18)

C_f，unit，i: concentration of nuclide i in plants, Bq/kg/Bq (m)²s) or Bq/L/Bq (m)²s); i is a nuclide¹²⁹I；

d_i(x) The method comprises the following steps Annual average deposition rate of nuclide i, including dry and wet deposition, Bq s/m²；

V_T: dry and wet deposition rates, m/s,¹²⁹taking 0.002;

C_air，i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

x: distance, m, of the release point to the calculation point.

Further, as to the system for evaluating the influence of the radiation environment of the special nuclide in the post-processing plant, the nuclide dose evaluation result output module is specifically configured to: calculating public dose of nuclide T, and public dose of tritium, including inhalation dose and ingestion dose, by the following formula:

H_E(atoms)，i(x)＝H_E(inh)，i(x)+H_{E(ing)，f，r，i}(x) (19)

1) the inhaled dose, calculated by the formula:

H_E(inh)，i(x) The method comprises the following steps The inhaled dose of the nuclide i, Sv, at a distance x from the release point; i is a nuclide T;

C_air，i(x) (ii) a Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

D_inh，i: the inhaled dose conversion factor, Sv/Bq, H-3, of nuclide i is 4.5X 10^-11；

I_inh: respiration rate, m³Taking 20;

86400: conversion factor, s/d;

O_ann: annual residence time, 3.15X 10⁷s；

x: distance, m, from the release point to the calculation point;

c in the formula (20) is calculated by the following formula_air，i(x)：

C_air，i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

Q: release rate, Bq/s;

D_i: diffusion factor, s/m, of a nuclide i at a distance x from the release point³；

X: the distance km from the release point to the calculation point;

n: an experience factor, T is 1.2;

λ_i: decay constant, s, of a nuclide i^-1；

u_a: the wind speed at the release altitude, km/s;

2) the intake dose is calculated by the following formula:

H_{E(ing)，f，r，i}(x)＝C_f，i(x)·D_ing，i·F_local·I_f，r (22)

H_{E(ing)，f，r，i}(x) The method comprises the following steps The ingested dose of nuclide i, Sv;

C_f，i(x) The method comprises the following steps The concentration of nuclide i in the product is Bq/kg or Bq/L;

D_ing，i: an ingestion dose conversion factor of nuclide i, Sv/Bq;

F_local: a local share of food;

I_f，r: yield of food in the region, kg or L.

Further, as to the system for evaluating the influence of the radiation environment of the special nuclide in the post-processing plant, the nuclide dose evaluation result output module is specifically configured to: calculating nuclides¹⁴C the dosage of the medicine for the public,¹⁴c public dose includes inhalantsThe dose, the dose of air-immersed external irradiation and the dose of ingestion were calculated by the following formula:

H_E(atoms)，i(x)＝H_E(inh)，i(x)+H_{E(ing)，f，r，i}(x) (23)

1) the inhaled dose, calculated by the formula:

H_E(inh)，i(x) The method comprises the following steps The inhaled dose of the nuclide i, Sv, at a distance x from the release point; i is a nuclide¹⁴C；

C_air，i(x) (ii) a Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

D_inh，i: an inhaled dose conversion factor for nuclide i, Sv/Bq;

I_inh: respiration rate, m³(d) adult 20;

86400: conversion factor, s/d;

O_ann: annual residence time, 3.15X 10⁷s；

x: distance, m, from the release point to the calculation point;

c in the formula (24) is obtained by the following calculation_air，i(x)：

C_air，i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

Q: release rate, Bq/s;

D_i: diffusion factor, s/m, of a nuclide i at a distance x from the release point³；

X: the distance of the release point downwind, km;

n: the value of the empirical factor is determined,¹⁴taking 1.4 as C;

λ_i: decay constant, s, of a nuclide i^-1；

u_a: the wind speed at the release altitude, km/s;

2) the air immersion external irradiation dose is calculated by the following formula:

H_{E(ex，cloud)，i}(x)＝C_air，i(x)·D_{ex，cloud，i}·O_ann·(O_out+(1-O_out)·L_cloud) (26)

H_{E(ex，cloud)，i}(x) The method comprises the following steps The plume immersion induced dose, Sv/a, of the nuclide i at a distance x from the release point;

O_ann: annual residence time, s/a;

D_{ex，cloud，i}: conversion factor of smoke plume immersion dose, Sv/(Bq s/m)³)；

O_out: taking 0.2 of outdoor share;

L^c _loud: taking 0.2 as a shielding factor of the building;

C_air，i(x) The method comprises the following steps Activity concentration of a nuclide i in air, Bq/m, at a distance x from the release point³；

3) The intake dose is calculated by the following formula:

H_{E(ing)，f，r，i}(x)＝C_f，i(x)·D_ing，i·F_local·I_f，r (27)

H_{E(ing)，f，r，i}(x) The method comprises the following steps The ingested dose of nuclide i, Sv;

C_f，i(x) The method comprises the following steps The concentration of nuclide i in the product is Bq/kg or Bq/L;

D_ing，i: an ingestion dose conversion factor of nuclide i, Sv/Bq;

F_local: a local share of food;

I_f，r: yield of food in the region, kg or L.

Further, as to the system for evaluating the influence of the radiation environment of the special nuclide in the post-processing plant, the nuclide dose evaluation result output module is specifically configured to: calculating nuclides¹²⁹I the dosage for the public due to the general formula,¹²⁹the public dose caused by I comprises an inhaled dose and a blankThe gas immersion external irradiation dose, the surface sediment external irradiation dose and the ingestion dose are calculated by the following formula:

H_E(atoms)，i(x)＝H_E(inh)，i(x)+H_{E(ex，cloud)}，i(x)+H_{E(ex，deposit)，i}(x)+H_{E(ing)，f，r，i}(x) (28)

1) the inhaled dose, calculated by the formula:

H_E(inh)，i(x) The method comprises the following steps The inhaled dose of the nuclide i, Sv, at a distance x from the release point; i is a nuclide¹²⁹I；

C_air，i(x) (ii) a Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

D_inh，i: an inhaled dose conversion factor for nuclide i, Sv/Bq;

I_inh: respiration rate, m³/d；

86400: conversion factor, s/d;

O_ann: annual residence time, 3.15X 10^7w；

x: distance, m, from the release point to the calculation point;

c in the formula (29) is obtained by the following calculation_air，i(x)：

C_air，i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

Q: release rate, Bq/s;

D_i: diffusion factor, s/m, of a nuclide i at a distance x from the release point³；

X: the distance of the release point downwind, km;

n: the value of the empirical factor is determined,¹²⁹taking 1.42 as I;

λ_i: decay constant, s, of a nuclide i^-1；

u_a: the wind speed at the release altitude, km/s;

2) the air immersion external irradiation dose is calculated by the following formula:

H_{E(ex，cloud)，i}(x)＝C_air，i(x)·D_{ex，cloud，i}·O_ann·(O_out+(1-O_out)·L_cloud) (31)

H_{E(ex，cloud)，i}(x) The method comprises the following steps The plume immersion induced dose, Sv/a, of the nuclide i at a distance x from the release point;

O_ann: annual residence time, s/a;

D_{ex，cloud，i}: conversion factor of smoke plume immersion dose, Sv/(Bq s/m)³)；

O_out: taking 0.2 of outdoor share;

L_cloud: taking 0.2 as a shielding factor of the building;

C_air，i(x) The method comprises the following steps Activity concentration of a nuclide i in air, Bq/m, at a distance x from the release point³；

3) The irradiation dose outside the surface deposit is calculated by the following formula:

H_{E(ex，deposit)，i}(x)＝d_i(x)·t_discharge·D_{ex，deposit，i}·(O_out+(1-O_out)·L_deposit) (32)

H_{E(ex，deposit)，i}(x) The method comprises the following steps The dose, Sv, caused by external irradiation of the surface deposit of the nuclide i;

d_i(x) The method comprises the following steps Annual average deposition rate of nuclide i, including dry and wet deposition, Bq s/m²；

t_discharge: deposition time, 3.15X 10⁷s；

D_{ex，deposit，i}: dose conversion factor for nuclide i, Sv/(Bq/m)²)；

O_out: taking 0.2 of outdoor share;

L_deposit: shielding factor of building is taken as 0.1；

4) The intake dose is calculated by the following formula:

H_{E(ing)，f，r，i}(x)＝C_f，i(x)·D_ing，i·F_local·I_f，r (33)

H_{E(ing)，f，r，i}(x) The method comprises the following steps The ingested dose of nuclide i, Sv;

C_f，i(x) The method comprises the following steps The concentration of nuclide i in the product is Bq/kg or Bq/L;

D_ing，i: an ingestion dose conversion factor of nuclide i, Sv/Bq;

F_local: a local share of food;

I_f，r: yield of food in the region, kg or L;

the nuclide dose evaluation result output module is specifically configured to: calculating nuclides⁸⁵The dose in the public domain due to Kr,⁸⁵the public radiation pathway induced by Kr is air immersion external irradiation, calculated by the following formula:

H_{E(ex，cloud)，i}(x)＝C_air，i(x)·D_{ex，cloud，i}·O_ann·(O_out+(1-O_out)·L_cloud) (34)

H_{E(ex，cloud)，i}(x) The method comprises the following steps The plume immersion induced dose, Sv/a, of the nuclide i at a distance x from the release point; i is a nuclide⁸⁵Kr；

O_ann: annual residence time, s/a;

D_{ex，cloud，i}: conversion factor of smoke plume immersion dose, Sv/(Bq s/m)³)；

O_out: taking 0.2 of outdoor share;

L_cloud: taking 0.2 as a shielding factor of the building;

C_air，i(x) The method comprises the following steps Activity concentration of a nuclide i in air, Bq/m, at a distance x from the release point³；

x: distance, m, of the release point to the calculation point.

The invention has the beneficial effects that: the invention calculates the atmospheric concentration in the environmental air of the special nuclide airborne carrier and the public annual effective dose caused by the atmospheric concentration in the environmental air of the special nuclide under the normal working condition through a special nuclide basic information module, a site characteristic data module, a nuclide release source item module, an atmospheric diffusion module, an environmental medium special nuclide concentration calculation module and a nuclide dose evaluation result output module, and realizes the public radiation dose evaluation of the key pollutant emission of the post-treatment plant.

Drawings

FIG. 1 is a schematic structural diagram of an evaluation system for radiation environmental impact of a special nuclide in an aftertreatment plant according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of the critical exposure paths for the public dose due to each specific nuclear species provided in an embodiment of the present invention.

Detailed Description

The invention is described in further detail below with reference to the drawings and the detailed description.

In order to solve the problem of effective evaluation of public radiation influence caused by nuclide release of effluents of a post-treatment plant in the future, the invention urgently needs to establish a special nuclide radiation environment influence evaluation system of the post-treatment plant, determine main radiation dose sources of nuclides through migration behavior research and key path identification of the special nuclides, obtain evaluation modes of different nuclides and establish an evaluation system of the special nuclides of the post-treatment plant.

As shown in fig. 1, a system for evaluating the influence of radiation on a special nuclide in an aftertreatment plant comprises: the system comprises a special nuclide basic information module, a field address characteristic data module, a nuclide release source item module, an atmospheric diffusion module, an environment medium special nuclide concentration calculation module and a nuclide dose evaluation result output module. The module is also used for data storage management, including data input, modification, export and query functions, and outputting related data according to the radiation environment influence evaluation requirements. The main function of the system is to calculate the atmospheric concentration of the special nuclide airborne carrier in the ambient air under normal working conditions and the annual effective dose of the carrier in the public.

(1) Special nuclide basic information module

The special nuclide basic information module mainly comprises a nuclide T,¹⁴C、⁸⁵Kr and¹²⁹basic information of I, half-life (T)_1/2) Decay constant (λ), dose conversion factor.

And (4) screening the public key irradiation ways caused by the special nuclide according to the property of the special nuclide. Wherein, the tritium-induced public dose includes an inhalation dose and an ingestion dose.¹⁴The public dose due to C includes inhalation dose, air submerged external irradiation dose, and ingestion dose.¹²⁹The public dose for I includes inhalation dose, air immersion external irradiation dose, surface deposition external irradiation dose and ingestion dose.⁸⁵The public radiation route by Kr is air immersion external irradiation. Setting an inhalation dose rate conversion factor (DF) in a module_inh) Air immersion external irradiation conversion factor (DF)_clo) Surface depositional external irradiation conversion factor (DF)_dep) Dietary dose conversion factor (DF)_ing) The information parameter of (1). The settings of the parameters are shown in Table 1.

TABLE 1 Special nuclide basic information parameters

(2) Site characteristic data module

The site characteristic data module is site basic information and mainly comprises plant site environment parameters and population recipe parameters. The plant site environment parameters comprise average wind speed and stability at the release height. The stability can be obtained from weather station data in the vicinity of the facility. The population recipe parameters comprise the population distribution of the factory site evaluation range and the site recipe data. Site recipe data includes the yield of food (meat, milk, eggs, vegetables, grains, etc.) from the site area, the intake of different types of food (meat, milk, eggs, vegetables, grains, etc.) and the intake share from the evaluation area.

(3) Nuclide release source item module

The nuclide release source item module mainly comprises release parameters and pollutant parameters. The release parameters include the number of the release chimney, the height of the chimney, the air exhaust rate and the height of the adjacent building. The pollution source parameters include nuclide name and annual release amount.

(4) Atmospheric diffusion module

The atmospheric diffusion module uses a dilution mode for calculation. And calling basic parameters from the site characteristic data module and the nuclide release source item module, and outputting diffusion factors and the nuclide ambient air concentration after calculation by corresponding formulas.

The atmospheric dispersion mode adopts a dilution mode, and the dilution effect of the atmosphere is considered, and the rising of the smoke plume is not considered. Different forms of calculation formulas are adopted according to the height of the emission source, the height of the adjacent highest building and the distance between the receiving point and the emission point.

1) If the source height is greater than 2.5 times the height H of the next highest building_bI.e. H > 2.5H_bThen, the atmospheric diffusion factor is calculated by the following formula:

C_air，i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

Q_i: nuclide release rate, Bq/s;

D_i: atmospheric diffusion factor, s/m³；

P_p: the time share of the fan-shaped direction p of the wind blowing to the receiving point in one year is 0.25;

f: release Gauss diffusion factor of height (H) 1/m at x km downwind distance release point²；

u_a: mean annual wind speed, m/s, over the release height. (ii) a

H: emission source height, m;

H_b: height adjacent to the highest building, m.

U in the formula (1) is obtained by the following formula calculation_a：

u₁₀: the wind speed at the height of 10m from the ground is m/s;

h: emission source height, m;

n: the wind profile coefficient.

The values of the wind profile coefficient n are shown in table 2 below.

TABLE 2 wind Profile coefficients

F in formula (1) is calculated by the following formula:

x: distance, m, from the release point to the calculation point;

σ_z: vertical diffusion parameter, m.

If H is less than or equal to 45m, the formula (3) is

2) If the release height H is less than or equal to 2.5H_bAnd is and

the atmospheric diffusion factor is calculated by the following formula:

C_air，i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

Q_i: nuclide release rate, Bq/s;

D_i: atmospheric diffusion factor, s/m³；

P_p: the time share of the fan-shaped direction p of the wind blowing to the receiving point in one year is 0.25;

b: in the lower windGaussian diffusion factor at distance x, 1/m²；

u_a: annual average wind speed, m/s, over the release height;

h: emission source height, m;

H_b: height of adjacent highest building, m;

A_b: cross sectional area, m, adjacent to the highest building²。

B in formula (4) is calculated by the following formula:

σ_z: vertical diffusion parameter, m;

A_b: cross sectional area, m, adjacent to the highest building²。

3) If the release height H is less than or equal to 2.5H_bAnd is and

and if the receiving point is not on the surface of the building where the releasing point is located, calculating the atmospheric diffusion factor by the following formula:

C_air，i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

Q_i: nuclide release rate, Bq/s;

D_i: atmospheric diffusion factor, s/m³；

P_p: the time share of the fan-shaped direction p of the wind blowing to the receiving point in one year is 0.25;

u_a: at release height of last yearAverage wind speed, m/s;

k: taking an empirical constant of 1 m;

h: emission source height, m;

H_b: height of adjacent highest building, m;

A_b: cross sectional area, m, adjacent to the highest building²。

(5) Special nuclide concentration calculation module for environmental medium

The calculation module for the concentration of the special nuclide in the environmental medium is obviously different from the evaluation system for other nuclides. The module can call parameters of an atmospheric diffusion module and a nuclide release source item module, embeds evaluation parameters, and calculates the concentration of special nuclides of soil, plant products and animal products. The module has built-in evaluation parameters.

1. Nuclide T

The method specifically comprises the following steps: HTO concentration in soil, HTO concentration in plant products, HTO concentration in drinking water and forage water, HTO concentration in terrestrial animal and plant products, OBT concentration in terrestrial products (crops, vegetables, forage), OBT concentration in animal products.

1) The HTO concentration in the soil is calculated by the following formula:

C_sw，HTO(x) The method comprises the following steps The concentration of HTO in the soil water at a distance x from the release point, Bq/L;

CR_s-a: an empirical constant;

C_air，HTO(x) The method comprises the following steps Concentration of HTO in air, Bq/m, at a distance x from the release point³；

H_a: absolute humidity, L/m³。

2) The HTO concentration in the plant product was calculated by the following formula:

C_f，HTO(x) The method comprises the following steps In thatThe concentration of HTO in the plant product at a distance x from the release point, fresh weight, Bq/kg;

WC_P: water content (fresh weight) of the plant, L/kg;

RH: relative humidity;

C_air，HTO(x) The method comprises the following steps Concentration of HTO in air, Bq/m, at a distance x from the release point³；

H_a: absolute humidity, L/m³；

C_sw，HTO(x) The method comprises the following steps The concentration of HTO in the soil water at a distance x from the release point, Bq/L;

γ: ratio of the saturated vapor pressure of HTO in water.

3) The HTO concentration in the drinking water and the forage water is calculated by the following formula:

CR_f，HTO(x) The method comprises the following steps HTO concentration in drinking/forage water (assuming 50% intake from drinking water, 50% from forage), Bq/L;

C_sw，HTO(x) The method comprises the following steps The concentration of HTO in the soil water at a distance x from the release point, Bq/L;

C_{pasture，HTO}(x) The method comprises the following steps The concentration of HTO in the soil water at a distance x from the release point, Bq/kg;

WC_P: water content (fresh weight) of the plant, L/kg.

4) The HTO concentration in the terrestrial plant product is calculated by the following formula:

C_f，HTO(x)＝CR_a，HTO·CR_f，HTO(x) (11)

C_f，HTO(x) The method comprises the following steps HTO concentration in the terrestrial plant product, Bq/kg;

CR_a，HTO(x) The method comprises the following steps The ratio of the activity concentration of the ingested HTO in the absorption of water and tritium is L/kg.

5) The concentration of OBT in terrestrial products (crops, vegetables, forage) is calculated by the following formula:

C_f，OBT(x) The method comprises the following steps The concentration of OBT in the animal product, Bq/kg;

WC_P: water content (fresh weight) of the plant, L/kg;

WEQ_P: water equivalent factor, L/kg;

R_p: a branching factor;

C_f，HTO(x) The method comprises the following steps Concentration of HTO in the plant product, Bq/kg.

6) The concentration of OBT in the animal product is calculated by the following formula:

C_f,OBT(x)＝CR_a,OBT·C_pasture,OBT(x) (13)

C_f，OBT(x) The method comprises the following steps The concentration of OBT in the animal product, Bq/kg;

CR_a，OBT(x) The method comprises the following steps The ratio of the activity concentration of ingested OBT in the feed tritium, L/kg;

C_{pasture，OBT}(x) The method comprises the following steps Average concentration of OBT in the feed, Bq/kg.

7) Related parameter

The relevant parameters for T are shown in Table 3 below.

Parameter(s)	Symbol	Value of	Unit of
				HTO：H2Saturated vapor pressure of O	γ	0.909	/
Absolute humidity	Ha	6×10-3	L/m3
				Relative humidity	RH	0.7	/
Empirical constant	CRs-a	0.3	/
				Share of water content in crop (fresh weight)	WCp	0.12	L/kg
Water content share in vegetables (fresh weight)	WCp	0.92	L/kg
				Water content share in forage (fresh weight)	WCp	0.76	L/kg
HTO concentration due to milk intake	CRa，HTO	0.87	Bq/kg fresh weight/Bq/L
				HTO concentration due to meat ingestion	CRa，HTO	0.66	Bq/kg fresh weight/Bq/L
Crop water equivalent factor	WEQp	0.56	L/kg
				Vegetable water equivalent factor	WEQp	0.51	L/kg
Forage water equivalent factor	WEQp	0.56	L/kg
				Branching factor of plant products	Rp	0.54	/
Concentration of OBT due to milk intake	CRa，OBT	0.24	Bq/kg fresh weight/Bq/kg dry weight
				Concentration of OBT due to meat consumption	CRa，OBT	0.4	Bq/kg fresh weight/Bq/kg dry weight

TABLE 3T calculation of relevant parameters

2. Nuclide¹⁴C

Suppose that¹⁴The concentration of C is the same as the concentration of stable C in plants and air. Used in calculating terrestrial products¹⁴Concentration of C, C_f，C-14(x) Plant product at a distance x from the release point¹⁴C concentration, polluted river water irrigation plant product¹⁴C concentration and animal product¹⁴The C concentration is calculated as follows.

1) Plant products¹⁴C concentration, calculated by the formula:

C_air，14C(x) The method comprises the following steps C-14 concentration at a distance x from the release point, Bq/m 3;

S_p: the concentration of stable carbon in the plant product, g C/kg fresh weight;

S_air: concentration of stable carbon in air, g C/m³；

SA_air: plant product specific activity Bq/g C.

2) Irrigation plant product for polluted river water¹⁴C concentration, calculated by the formula:

SA_air: plant product specific activity Bq/g C;

CD_s: a dilution factor, taking a value of 0.15;

I_irr: irrigation rate, 0.005m³/m²；

C_uw，s: activity concentration of nuclides in water, Bq/m³；

F_c: the rate of carbon production from decomposition of plant product residue, 0.66(g C)/m²。

3) Animal product¹⁴C concentration, calculated by the formula:

f_C：¹⁴c, taking 1 as a default value for the feeding share of the feed;

C_{pasture，14C}(x) The method comprises the following steps C-14 concentration in forage at distance x;

S_a: concentration of stable carbon in animal products, g C/kg fresh weight;

S_p: the concentration of stable carbon in the forage was g C/kg fresh weight.

4) Related parameter

¹⁴The relevant parameters for C are shown in table 4 below.

TABLE 4¹⁴C calculating the related parameters

3. Nuclide¹²⁹I

1) Nuclear elements in the environmental Medium¹²⁹I concentration, calculated by the formula:

C_f，i(x)＝C_f，unit，i·d_i(x) (17)

d_i(x)＝V_TC_air，i(x) (18)

C_f，unit，i: radionuclide concentration in plants (deposition considered 100 years), Bq/kg/Bq (m)²s) or Bq/LBq(m²s)；

d_i(x) The method comprises the following steps Annual average deposition rate, including dry and wet deposition, Bq s/m²；

V_T: taking the dry and wet deposition rate, m/s, I-129 to be 0.002;

C_air，i(x) The method comprises the following steps Concentration of nuclide i in air, Bq/m³。

2) Related parameter

¹²⁹The relevant parameters for I are shown in Table 5 below.

Parameter(s)	Symbol	Value of	Unit of
				In cereals129I concentration	Cf，unit，i	6.00E+05	Bq/kg/Bq(m2s)
In plants and fruits129I concentration	Cf，unit，i	2.30E+05	Bq/kg/Bq(m2s)
				In milk129I concentration	Cf，unit，i	3.10E+05	Bq/L/Bq(m2s)
Meat products129I concentration	Cf，unit，i	2.10E+05	Bq/kg/Bq(m2s)
				Deposition rate	VT	0.002	m/s

TABLE 5¹²⁹I calculating the relevant parameters

(6) Nuclide dose evaluation result output module

And the nuclide dose evaluation result output module is used for outputting the normal working condition inhalation internal irradiation dose, the air immersion external irradiation dose, the surface deposition external irradiation dose and the ingestion internal irradiation dose of each nuclide. Each nuclide includes: nuclide T, nuclide¹⁴C. Nuclide¹²⁹I. Nuclide⁸⁵Kr. Specifically, tritium-induced public doses include inhaled doses and ingested doses.¹⁴The public dose due to C includes inhalation dose, air submerged external irradiation dose, and ingestion dose.¹²⁹The public doses for I include inhalation doses, exposure to air immersion, exposure to surface deposits, and ingestion doses.⁸⁵The public radiation route by Kr is air immersion external irradiation. As shown in fig. 2.

1. Nuclide T

Tritium-induced public doses include inhaled doses and ingested doses. The total dose formula is as follows:

H_E(atoms)，i(x)＝H_E(inh)，i(x)+H_{E(ing)，f，r，i}(x) (19)

1) the inhaled dose, calculated by the formula:

H_E(inh)，i(x) The method comprises the following steps The inhaled dose of the nuclide i, Sv, at a distance x from the release point; i is a nuclide T;

C_air，i(x) (ii) a Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

D_inh，i: the inhaled dose conversion factor, Sv/Bq, H-3, of nuclide i is 4.5X 10^-11；

I_inh: respiration rate, m³Taking 20;

86400: conversion factor, s/d;

O_ann: annual residence time, 3.15X 10⁷s；

x: distance, m, from the release point to the calculation point;

c in the formula (20) is calculated by the following formula_air，i(x)：

C_air，i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

Q: release rate, Bq/s;

D_i: diffusion factor, s/m, of a nuclide i at a distance x from the release point³；

X: the distance km from the release point to the calculation point;

n: an experience factor, T is 1.2;

λ_i: decay constant, s, of a nuclide i^-1；

u_a: the wind speed at the release altitude, km/s;

2) the intake dose is calculated by the following formula:

H_{E(ing)，f，r，i}(x)＝C_f，i(x)·D_ing，i·F_local·I_f，r (22)

H_{E(ing)，f，r，i}(x) The method comprises the following steps The ingested dose of nuclide i, Sv;

C_f，i(x) The method comprises the following steps The concentration of nuclide i in the product is Bq/kg or Bq/L;

D_ing，i: an ingestion dose conversion factor of nuclide i, Sv/Bq;

F_local: a local share of food;

I_f，r: yield of food in the region, kg or L.

2. Nuclide¹⁴C

Nuclide¹⁴The public dose due to C includes the inhaled dose, the air-submerged external exposure dose, and the ingested dose, and is calculated by the following formula:

H_E(atoms)，i(x)＝H_E(inh)，i(x)+H_{E(ing)，f，r，i}(x) (23)

1) the inhaled dose, calculated by the formula:

H_E(inh)，i(x) The method comprises the following steps The inhaled dose of the nuclide i, Sv, at a distance x from the release point; i is a nuclide¹⁴C；

C_air，i(x) (ii) a Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

D_inh，i: an inhaled dose conversion factor for nuclide i, Sv/Bq;

I_inh: respiration rate, m³(d) adult 20;

86400: conversion factor, s/d;

O_ann: annual residence time, 3.15X 10⁷s；

x: distance, m, from the release point to the calculation point;

c in the formula (24) is obtained by the following calculation_air，i(x)：

C_air，i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

Q: release rate, Bq/s;

D_i: diffusion factor, s/m, of a nuclide i at a distance x from the release point³；

X: the distance of the release point downwind, km;

n: the value of the empirical factor is determined,¹⁴taking 1.4 as C;

λ_i: decay constant, s, of a nuclide i^-1；

u_a: the wind speed at the release altitude, km/s;

2) the air immersion external irradiation dose is calculated by the following formula:

H_{E(ex，clouir，i}(x)＝C_air，i(x)·D_{ex，cloud，i}·O_ann·(O_out+(1-O_out)·L_cloud) (26)

H_{E(ex，cloud)，i}(x) The method comprises the following steps The plume immersion induced dose, Sv/a, of the nuclide i at a distance x from the release point;

O_ann: annual residence time, s/a;

D_{ex，cloud，i}: conversion factor of smoke plume immersion dose, Sv/(Bq s/m)³)；

O_out: taking 0.2 of outdoor share;

L_cloud: taking 0.2 as a shielding factor of the building;

C_air，i(x) The method comprises the following steps Activity concentration of a nuclide i in air, Bq/m, at a distance x from the release point³；

3) The intake dose is calculated by the following formula:

H_{E(ing)，f，r，i}(x)＝C_f，i(x)·D_ing，i·F_local·I_f，r (27)

H_{E(ing)，f，r，i}(x) The method comprises the following steps The ingested dose of nuclide i, Sv;

C_f，i(x) The method comprises the following steps The concentration of nuclide i in the product is Bq/kg or Bq/L;

D_ing，i: an ingestion dose conversion factor of nuclide i, Sv/Bq;

F_local: a local share of food;

I_f，r: yield of food in the region, kg or L.

3. Nuclide¹²⁹I

Nuclide¹²⁹The public dose due to I includes the inhaled dose, the dose of air submerged external irradiation, the dose of surface sediment external irradiation and the dose of ingestion, and is calculated by the following formula:

H_E(atoms)，i(x)＝H_E(inh)，i(x)+H_{E(ex，cloud)，i}(x)+H_{E(ex，deposit)，i}(x)+H_{E(ing)，f，r，i}(x) (28)

1) the inhaled dose, calculated by the formula:

H_E(inh)，i(x) The method comprises the following steps The inhaled dose of the nuclide i, Sv, at a distance x from the release point; i is a nuclide¹²⁹I；

C_air，i(x) (ii) a Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

D_inh，i: an inhaled dose conversion factor for nuclide i, Sv/Bq;

I_inh: respiration rate, m³/d；

86400: conversion factor, s/d;

O_ann: annual residence time, 3.15X 10⁷s；

x: distance, m, from the release point to the calculation point;

c in the formula (29) is obtained by the following calculation_air，i(x)：

C_air，i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

Q: release rate, Bq/s;

D_i: diffusion factor, s/m, of a nuclide i at a distance x from the release point³；

X: the distance of the release point downwind, km;

n: the value of the empirical factor is determined,¹²⁹taking 1.42 as I;

λ_i: decay constant, s, of a nuclide i^-1；

u_a: the wind speed at the release altitude, km/s;

2) the air immersion external irradiation dose is calculated by the following formula:

H_{E(ex，cloud)，i}(x)＝C_air，i(x)·D_{ex，cloud，i}·C_ann·(O_out+(1-O_out)·L_cloud) (31)

H_{E(ex，cloud)，i}(x) The method comprises the following steps The plume immersion induced dose, Sv/a, of the nuclide i at a distance x from the release point;

O_ann: annual residence time, s/a;

D_{ex，cloud，i}: conversion factor of smoke plume immersion dose, Sv/(Bq s/m)³)；

O_out: taking 0.2 of outdoor share;

L_cloud: taking 0.2 as a shielding factor of the building;

C_air，i(x) The method comprises the following steps Activity concentration of a nuclide i in air, Bq/m, at a distance x from the release point³；

3) The external irradiation of the surface deposits is calculated by the following formula:

H_{E(ex，deposit)，i}(x)＝d_i(x)·t_discharge·D_{ex，deposit，i}·(O_out+(1-O_out)·L_deposit) (32)

H_{E(ex，deposit)，i}(x) The method comprises the following steps External irradiation of surface deposits of nuclide i, Sv;

d_i(x) The method comprises the following steps Annual average deposition rate of nuclide i, including dry and wet deposition, Bq s/m²；

t_discharge: deposition time, 3.15X 10⁷s；

D_{ex，deposit，i}: dose conversion factor for nuclide i, Sv/(Bq/m)²)；

O_out: taking 0.2 of outdoor share;

L_deposit: taking 0.1 as a building shielding factor;

4) the intake dose is calculated by the following formula:

H_{E(ing)，f，r，i}(x)＝C_f，i(x)·D_ing，i·F_local·I_f，r (33)

H_{E(ing)，f，r，i}(x) The method comprises the following steps The ingested dose of nuclide i, Sv;

C_f，i(x) The method comprises the following steps The concentration of nuclide i in the product is Bq/kg or Bq/L;

D_ing，i: an ingestion dose conversion factor of nuclide i, Sv/Bq;

F_local: a local share of food;

I_f，r: yield of food in the region, kg or L;

4. nuclide⁸⁵Kr

Nuclide⁸⁵The public radiation pathway induced by Kr is air immersion external irradiation, calculated by the following formula:

H_{E(ex，cloud)}，_i(x)＝C_air，i(x)·D_{ex，cloud，i}·O_ann·(O_out+(1-O_out)·L_cloud) (34)

H_{E(ex，cloud)，i}(x) The method comprises the following steps The plume immersion induced dose, Sv/a, of the nuclide i at a distance x from the release point; i is a nuclide⁸⁵Kr；

O_ann: annual residence time, s/a;

D_{ex，cloud，i}: conversion factor of smoke plume immersion dose, Sv/(Bq s/m)³)；

O_out: and taking 0 for outdoor share.2；

L_cloud: taking 0.2 as a shielding factor of the building;

C_air，i(x) The method comprises the following steps Activity concentration of a nuclide i in air, Bq/m, at a distance x from the release point³；

x: distance, m, of the release point to the calculation point.

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.

Claims (10)

1. A post-treatment plant special nuclide radiation environment influence evaluation system is characterized by comprising:

the special nuclide basic information module is used for storing basic information of each special nuclide, wherein the basic information comprises the half-life period, the decay constant and the dose conversion factor of each special nuclide; the method is also used for screening public key irradiation ways caused by each special nuclide according to the property of each special nuclide;

the site characteristic data module is used for storing site basic information, and the site basic information comprises plant site environment parameters and population recipe parameters;

the nuclide release source item module is used for storing release parameters and pollutant parameters;

the atmospheric diffusion module is used for calling parameters of the site characteristic data module and the nuclide release source item module, outputting atmospheric diffusion factors and nuclide ambient air concentration after calculation through corresponding calculation formulas, and determining to use different calculation formulas according to the height of the emission source, the height of the highest building adjacent to the emission source and the distance between the receiving point and the emission point;

the environment medium special nuclide concentration calculation module is used for calling parameters of the atmospheric diffusion module and the nuclide release source item module, internally setting evaluation parameters and calculating the concentration of special nuclides in soil, plant products and animal products;

and the nuclide dose evaluation result output module is used for calling all information parameters in the special nuclide basic information module, the site characteristic data module, the nuclide release source item module, the atmospheric diffusion module and the environment medium special nuclide concentration calculation module and calculating the public dose caused by each special nuclide based on the screened key irradiation way of the public caused by each special nuclide.

2. The system for evaluating the environmental impact of special nuclide radiation in an aftertreatment plant of claim 1, wherein the special nuclide basic information module, the site characteristic data module, the nuclide release source item module, the atmospheric diffusion module, the environmental medium special nuclide concentration calculation module, and the nuclide dose evaluation result output module are further configured to: managing various data stored by the system, including inputting, modifying, exporting and inquiring, and outputting relevant data according to the radiation environment influence evaluation requirement.

3. The evaluation system of claim 1, wherein the site environmental parameters comprise average wind speed and stability at a release height, the population recipe parameters comprise site evaluation range population distribution and site recipe data, and the site recipe data comprise yield of food in a site area, food intake of different types of food and intake share of an evaluation area;

the release parameters comprise a release chimney number, a chimney height, an exhaust rate and a height of an adjacent building, and the pollution source parameters comprise a nuclide name and an annual release amount.

4. The system for evaluating the influence of the radiation environment of the special nuclide in the aftertreatment plant as claimed in claim 1, wherein the atmospheric diffusion module is specifically configured to:

1) if the height H of the emission source is greater than 2.5 times the height H of the next highest building_bI.e. H>2.5H_bThen, the atmospheric diffusion factor is calculated by the following formula:

C_air，i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³(ii) a i is a nuclide T,¹⁴C、⁸⁵Kr or¹²⁹I；

Q_i: the release rate of the nuclide i, Bq/s;

D_i: atmospheric diffusion factor, s/m, of nuclide i³；

P_p: the time share of the fan-shaped direction p of the wind blowing to the receiving point in one year is 0.25;

f: releasing a Gaussian diffusion factor of height, namely emission source height H, 1/m at a downwind distance release point x²；

u_a: annual average wind speed, m/s, over the release height;

h: emission source height, m;

H_b: height of adjacent highest building, m;

x: distance, m, from the release point to the calculation point;

u in the formula (1) is obtained by the following formula calculation_a：

u₁₀: the wind speed at the height of 10m from the ground is m/s;

h: emission source height, m;

n: a wind profile coefficient;

f in formula (1) is calculated by the following formula:

x: distance, m, from the release point to the calculation point;

σ_z: vertical diffusion parameter, m;

if H is less than or equal to 45m, the formula (3) is

2) If the height H of the emission source is less than or equal to 2.5H_bAnd is and

the atmospheric diffusion factor is calculated by the following formula:

C_air，i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³(ii) a I is nuclide T, 14C, 85Kr or 129I;

Q_i: the release rate of the nuclide i, Bq/s;

D_i: atmospheric diffusion factor, s/m, of nuclide i³；

P_p: the time share of the fan-shaped direction p of the wind blowing to the receiving point in one year is 0.25;

b: gauss diffusion factor at downwind distance x, 1/m²；

u_a: annual average wind speed, m/s, over the release height;

h: emission source height, m;

H_b: height of adjacent highest building, m;

A_b: cross sectional area, m, adjacent to the highest building²；

x: distance, m, from the release point to the calculation point;

b in formula (4) is calculated by the following formula:

σ_z: vertical diffusion parameter, m;

A_b: cross sectional area, m, adjacent to the highest building²；

x: distance, m, from the release point to the calculation point;

3) if the height H of the emission source is less than or equal to 2.5H_bAnd is and

and if the receiving point is not on the surface of the building where the releasing point is located, calculating the atmospheric diffusion factor by the following formula:

C_air，i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³(ii) a I is nuclide T, 14C, 85Kr or 129I;

Q_i: the release rate of the nuclide i, Bq/s;

D_i: atmospheric diffusion factor, s/m, of nuclide i³；

P_p: the time share of the fan-shaped direction p of the wind blowing to the receiving point in one year is 0.25;

u_a: annual average wind speed, m/s, over the release height;

k: taking an empirical constant of 1 m;

h: emission source height, m;

H_b: height of adjacent highest building, m;

A_b: cross sectional area, m, adjacent to the highest building²；

x: distance, m, of the release point to the calculation point.

5. The system for evaluating the environmental impact of radiation of special nuclides in an aftertreatment plant as recited in claim 1, wherein the environmental medium special nuclide concentration calculation module is specifically configured to: calculating the concentration of HTO in soil, the concentration of HTO in plant products, the concentration of HTO in drinking water and forage water, the concentration of HTO in terrestrial animal and plant products, the concentration of OBT in terrestrial products and the concentration of OBT in animal products;

1) the HTO concentration in the soil is calculated by the following formula:

C_sw，HTO(x) The method comprises the following steps The concentration of HTO in the soil water at a distance x from the release point, Bq/L;

CR_s-a: an empirical constant;

C_air，HTO(x) The method comprises the following steps Concentration of HTO in air, Bq/m, at a distance x from the release point³；

H_a: absolute humidity, L/m³；

x: distance, m, from the release point to the calculation point;

2) the HTO concentration in the plant product was calculated by the following formula:

C_f，HTO(x) The method comprises the following steps The concentration of HTO in the plant product at a distance x from the release point, fresh weight, Bq/kg;

WC_P: water content of the plant, fresh weight, L/kg;

RH: relative humidity;

C_air，HTO(x) The method comprises the following steps Concentration of HTO in air, Bq/m, at a distance x from the release point³；

H_a: absolute humidity, L/m³；

C_sw，HTO(x) The method comprises the following steps The concentration of HTO in the soil water at a distance x from the release point, Bq/L;

γ: the ratio of the HTO saturated vapor pressure in water;

x: distance, m, from the release point to the calculation point;

3) the HTO concentration in the drinking water and the forage water is calculated by the following formula:

CR_f，HTO(x) The method comprises the following steps HTO concentration in drinking/forage water (assuming 50% intake from drinking water, 50% from forage), Bq/L;

C_sw，HTO(x) The method comprises the following steps The concentration of HTO in the soil water at a distance x from the release point, Bq/L;

C_{pasture，HTO}(x) The method comprises the following steps The concentration of HTO in the soil water at a distance x from the release point, Bq/kg;

WC_P: water content (fresh weight) of the plant, L/kg;

x: distance, m, from the release point to the calculation point;

4) the HTO concentration in the terrestrial plant product is calculated by the following formula:

C_f,HTO(x)＝CR_a,HTO·CR_f,HTO(x) (11)

C_f，HTO(x) The method comprises the following steps HTO concentration in the terrestrial plant product, Bq/kg;

CR_a，HTO(x) The method comprises the following steps The ratio of the activity concentration of the ingested HTO in the absorption of water and tritium is L/kg;

x: distance, m, from the release point to the calculation point;

5) the concentration of OBT in the terrestrial product is calculated by the following formula:

C_f，OBT(x) The method comprises the following steps The concentration of OBT in the animal product, Bq/kg;

WC_P: water content (fresh weight) of the plant, L/kg;

WEQ_P: water equivalent factor, L/kg;

R_p: a branching factor;

C_f，HTO(x) The method comprises the following steps The concentration of HTO in the plant product, Bq/kg;

x: distance, m, from the release point to the calculation point;

6) the concentration of OBT in the animal product is calculated by the following formula:

C_f,OBT(x)＝CR_a,OBT·C_pasture,OBT(x) (13)

C_f，OBT(x) The method comprises the following steps The concentration of OBT in the animal product, Bq/kg;

CR_a，OBT(x) The method comprises the following steps The ratio of the activity concentration of ingested OBT in the feed tritium, L/kg;

C_{pasture，OBT}(x) The method comprises the following steps The average concentration of OBT in the feed, Bq/kg;

x: distance, m, of the release point to the calculation point.

6. The system for evaluating the environmental impact of radiation of special nuclides in an aftertreatment plant as recited in claim 1, wherein the environmental medium special nuclide concentration calculation module is specifically configured to: calculating plant products¹⁴C concentration, polluted river water irrigation plant product¹⁴C concentration and animal product¹⁴C concentration;

1) plant products¹⁴C concentration, calculated by the formula:

C_air，14C(x) The method comprises the following steps C-14 concentration at a distance x from the release point, Bq/m 3;

S_p: the concentration of stable carbon in the plant product, g C/kg fresh weight;

S_air: concentration of stable carbon in air, g C/m³；

SA_air: plant product specific activity Bq/g C;

x: distance, m, from the release point to the calculation point;

2) irrigation plant product for polluted river water¹⁴C concentration, calculated by the following formula：

SA_air: plant product specific activity Bq/g C;

CD_s: a dilution factor, taking a value of 0.15;

I_irr: irrigation rate, 0.005m³/m²；

C_uw，s: activity concentration of nuclides in water, Bq/m³；

F_c: the rate of carbon production from decomposition of plant product residue, 0.66(g C)/m²；

x: distance, m, from the release point to the calculation point;

3) animal product¹⁴C concentration, calculated by the formula:

f_C：¹⁴c, taking 1 as a default value for the feeding share of the feed;

C_{pasture，14C}(x) The method comprises the following steps C-14 concentration in the forage at a distance x from the release point;

S_a: concentration of stable carbon in animal product, fresh weight, g C/kg;

S_p: the concentration and fresh weight of stable carbon in the forage are g C/kg;

x: distance, m, of the release point to the calculation point.

7. The system for evaluating the environmental impact of radiation of special nuclides in an aftertreatment plant as recited in claim 1, wherein the environmental medium special nuclide concentration calculation module is specifically configured to: nucleic acids in computing environment media¹²⁹The concentration of I is calculated by the following formula:

C_f,i(x)＝C_f,unit,i·d_i(x) (17)

d_i(x)＝V_TC_air,i(x) (18)

C_f，unit，i: concentration of nuclide i in plants, Bq/kg/Bq (m)²s) or Bq/L/Bq (m)²s); i is a nuclide¹²⁹I；

d_i(x) The method comprises the following steps Annual average deposition rate of nuclide i, including dry and wet deposition, Bq s/m²；

V_T: dry and wet deposition rates, m/s,¹²⁹taking 0.002;

C_air，i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

x: distance, m, of the release point to the calculation point.

8. The system for evaluating influence of radiation on environment of special nuclides in an aftertreatment plant as claimed in claim 1, wherein the nuclide dose evaluation result output module is specifically configured to: calculating public dose of nuclide T, and public dose of tritium, including inhalation dose and ingestion dose, by the following formula:

H_E(atoms),i(x)＝H_E(inh),i(x)+H_E(ing),f,r,i(x) (19)

1) the inhaled dose, calculated by the formula:

H_E(inh),i(x) The method comprises the following steps The inhaled dose of the nuclide i, Sv, at a distance x from the release point; i is a nuclide T;

C_air,i(x) (ii) a Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

D_inh,i: the inhaled dose conversion factor, Sv/Bq, H-3, of nuclide i is 4.5X 10^-11；

I_inh: respiration rate, m³Taking 20;

86400: conversion factor, s/d;

O_ann: the time of the year is kept,3.15×10⁷s；

x: distance, m, from the release point to the calculation point;

c in the formula (20) is calculated by the following formula_air,i(x)：

C_air,i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

Q: release rate, Bq/s;

D_i: diffusion factor, s/m, of a nuclide i at a distance x from the release point³；

X: the distance km from the release point to the calculation point;

n: an experience factor, T is 1.2;

λ_i: decay constant, s, of a nuclide i^-1；

u_a: the wind speed at the release altitude, km/s;

2) the intake dose is calculated by the following formula:

H_E(ing),f,r,i(x)＝C_f,i(x)·D_ing,i·F_local·I_f,r (22)

H_E(ing),f,r,i(x) The method comprises the following steps The ingested dose of nuclide i, Sv;

C_f,i(x) The method comprises the following steps The concentration of nuclide i in the product is Bq/kg or Bq/L;

D_ing,i: an ingestion dose conversion factor of nuclide i, Sv/Bq;

F_local: a local share of food;

I_f,r: yield of food in the region, kg or L.

9. The system for evaluating influence of radiation on environment of special nuclides in an aftertreatment plant as claimed in claim 1, wherein the nuclide dose evaluation result output module is specifically configured to: calculating nuclides¹⁴C the dosage of the medicine for the public,¹⁴c public dose includes inhalationThe dose, the dose of air-immersed external irradiation and the dose of ingestion were calculated by the following formula:

H_E(atoms),i(x)＝H_E(inh),i(x)+H_E(ing),f,r,i(x) (23)

1) the inhaled dose, calculated by the formula:

H_E(inh),i(x) The method comprises the following steps The inhaled dose of the nuclide i, Sv, at a distance x from the release point; i is a nuclide¹⁴C；

C_air,i(x) (ii) a Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

D_inh,i: an inhaled dose conversion factor for nuclide i, Sv/Bq;

I_inh: respiration rate, m³(d) adult 20;

86400: conversion factor, s/d;

O_ann: annual residence time, 3.15X 10⁷s；

x: distance, m, from the release point to the calculation point;

c in the formula (24) is obtained by the following calculation_air,i(x)：

C_air,i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

Q: release rate, Bq/s;

D_i: diffusion factor, s/m, of a nuclide i at a distance x from the release point³；

X: the distance of the release point downwind, km;

n: the value of the empirical factor is determined,¹⁴taking 1.4 as C;

λ_i: decay constant, s, of a nuclide i^-1；

u_a: the wind speed at the release altitude, km/s;

2) the air immersion external irradiation dose is calculated by the following formula:

H_{E(ex,cloud),i}(x)＝C_air,i(x)·D_ex,cloud,i·O_ann·(O_out+(1-O_out)·L_cloud) (26)

H_{E(ex,cloud),i}(x) The method comprises the following steps The plume immersion induced dose, Sv/a, of the nuclide i at a distance x from the release point;

O_ann: annual residence time, s/a;

D_ex,cloud,i: conversion factor of smoke plume immersion dose, Sv/(Bq s/m)³)；

O_out: taking 0.2 of outdoor share;

L_cloud: taking 0.2 as a shielding factor of the building;

C_air,i(x) The method comprises the following steps Activity concentration of a nuclide i in air, Bq/m, at a distance x from the release point³；

3) The intake dose is calculated by the following formula:

H_E(ing),f,r,i(x)＝C_f,i(x)·D_ing,i·F_local·I_f,r (27)

H_E(ing),f,r,i(x) The method comprises the following steps The ingested dose of nuclide i, Sv;

C_f,i(x) The method comprises the following steps The concentration of nuclide i in the product is Bq/kg or Bq/L;

D_ing,i: an ingestion dose conversion factor of nuclide i, Sv/Bq;

F_local: a local share of food;

I_f,r: yield of food in the region, kg or L.

10. The system for evaluating influence of radiation on environment of special nuclides in an aftertreatment plant as claimed in claim 1, wherein the nuclide dose evaluation result output module is specifically configured to: calculating nuclides¹²⁹I the dosage for the public due to the general formula,¹²⁹the public dose includes inhalation dose, air immersion external irradiation agentThe dose, the external irradiation dose for surface deposition and the dose for ingestion are calculated by the following formula:

H_E(atoms),i(x)＝H_E(inh),i(x)+H_{E(ex,cloud),i}(x)+H_{E(ex,deposit),i}(x)+H_E(ing),f,r,i(x) (28)

1) the inhaled dose, calculated by the formula:

H_E(inh),i(x) The method comprises the following steps The inhaled dose of the nuclide i, Sv, at a distance x from the release point; i is a nuclide¹²⁹I；

C_air,i(x) (ii) a Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

D_inh,i: an inhaled dose conversion factor for nuclide i, Sv/Bq;

I_inh: respiration rate, m³/d；

86400: conversion factor, s/d;

O_ann: annual residence time, 3.15X 10⁷s；

x: distance, m, from the release point to the calculation point;

c in the formula (29) is obtained by the following calculation_air,i(x)：

C_air,i(x) The method comprises the following steps Concentration of a nuclide i in air, Bq/m, at a distance x from the release point x³；

Q: release rate, Bq/s;

D_i: diffusion factor, s/m, of a nuclide i at a distance x from the release point³；

X: the distance of the release point downwind, km;

n: the value of the empirical factor is determined,¹²⁹taking 1.42 as I;

λ_i: decay of the nuclide iVariable constant, s^-1；

u_a: the wind speed at the release altitude, km/s;

2) the air immersion external irradiation dose is calculated by the following formula:

H_{E(ex,cloud),i}(x)＝C_air,i(x)·D_ex,cloud,i·O_ann·(O_out+(1-O_out)·L_cloud) (31)

H_{E(ex,cloud),i}(x) The method comprises the following steps The plume immersion induced dose, Sv/a, of the nuclide i at a distance x from the release point;

O_ann: annual residence time, s/a;

D_ex,cloud,i: conversion factor of smoke plume immersion dose, Sv/(Bq s/m)³)；

O_out: taking 0.2 of outdoor share;

L_cloud: taking 0.2 as a shielding factor of the building;

C_air,i(x) The method comprises the following steps Activity concentration of a nuclide i in air, Bq/m, at a distance x from the release point³；

3) The irradiation dose outside the surface deposit is calculated by the following formula:

H_{E(ex,deposit),i}(x)＝d_i(x)·t_discharge·D_ex,deposit,i·(O_out+(1-O_out)·L_deposit) (32)

H_{E(ex,deposit),i}(x) The method comprises the following steps The dose, Sv, caused by external irradiation of the surface deposit of the nuclide i;

d_i(x) The method comprises the following steps Annual average deposition rate of nuclide i, including dry and wet deposition, Bq s/m²；

t_discharge: deposition time, 3.15X 10⁷s；

D_ex,deposit,i: dose conversion factor for nuclide i, Sv/(Bq/m)²)；

O_out: taking 0.2 of outdoor share;

L_deposit: taking 0.1 as a building shielding factor;

4) the intake dose is calculated by the following formula:

H_E(ing),f,r,i(x)＝C_f,i(x)·D_ing,i·F_local·I_f,r (33)

H_E(ing),f,r,i(x) The method comprises the following steps The ingested dose of nuclide i, Sv;

C_f,i(x) The method comprises the following steps The concentration of nuclide i in the product is Bq/kg or Bq/L;

D_ing,i: an ingestion dose conversion factor of nuclide i, Sv/Bq;

F_local: a local share of food;

I_f,r: yield of food in the region, kg or L;

the nuclide dose evaluation result output module is specifically configured to: calculating nuclides⁸⁵The dose in the public domain due to Kr,⁸⁵the public radiation pathway induced by Kr is air immersion external irradiation, calculated by the following formula:

H_{E(ex,cloud),i}(x)＝C_air,i(x)·D_ex,cloud,i·O_ann·(O_out+(1-O_out)·L_cloud) (34)

H_{E(ex,cloud),i}(x) The method comprises the following steps The plume immersion induced dose, Sv/a, of the nuclide i at a distance x from the release point; i is a nuclide⁸⁵Kr；

O_ann: annual residence time, s/a;

D_ex,cloud,i: conversion factor of smoke plume immersion dose, Sv/(Bq s/m)³)；

O_out: taking 0.2 of outdoor share;

L_cloud: taking 0.2 as a shielding factor of the building;

C_air,i(x) The method comprises the following steps Activity concentration of a nuclide i in air, Bq/m, at a distance x from the release point³；

x: distance, m, of the release point to the calculation point.

Images